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Background: Floodplains harbor highly biodiverse ecosystems, which have been strongly affected by both past climate change and by recent human activities, resulting in a high prevalence of many endangered species in these habitats. Understanding the history of floodplain species over a wide range of timescales can contribute to effective conservation planning. We reconstructed the population formation history of the Itasenpara bitterling Acheilognathus longipinnis, an endangered floodplain fish species in Japan, over a broad timescale based on phylogenetic analysis, demographic modeling, and historical demographic analysis using mitogenome and whole-genome sequences. A genome sequence was newly assembled as a reference for the resequencing analysis. This bitterling is distributed in three plains separated by high mountain ranges and exhibits ecological characteristics well adapted to floodplain environments., Results: Our analyses revealed an unexpected population branching pattern, gene flow, and timing of the differentiation that occurred within a few hundred thousand years, i.e., long after the mountain uplift that was assumed to be the primary geological cause of the population differentiation. The analyses also showed that all local populations experienced a severe decline during the last glacial and post-glacial periods., Conclusions: Our results suggest that the floodplain bitterling was able to disperse through unknown routes after mountain uplift and that its populations were strongly influenced by climatic and geographic changes in glacial-interglacial cycles and subsequent human activities, probably related to its floodplain-dependent ecology. The genomic data highlight the unanticipated distribution process of this species and the magnitude of the impact of human activities, with important implications for its conservation., Competing Interests: Declarations Ethics approval and consent to participate Acheilognathus longipinnis is a legally protected species designated as a Natural Monument of Japan and a “nationally rare species of wild fauna and flora” in Act on Conservation of Endangered Species of Wild Fauna and Flora, Japan. We obtained permission to conduct this research from the Agency for Cultural Affairs and the Ministry of the Environment, Japan. The described methods were conducted in compliance with the Regulation on Animal Experimentation at Kyoto University and were approved by the Kyoto University Animal Experimentation Committee. This article does not contain any studies with human participants. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Advancements in genome sequencing technology have brought unprecedented accessibility of high-throughput sequencing to species of conservation interest. The potential knowledge gained from application of these techniques is maximized by availability of high-quality, annotated reference genomes for endangered species. However, these vital resources are often lacking for endangered minnows of North America (Cypriniformes: Leuciscidae). One such endangered species, Colorado pikeminnow (Ptychocheilus lucius), is the largest North American minnow and the top-level native aquatic predator in the Colorado River Basin of the southwestern United States and northwestern Mexico. Over the past century, Colorado pikeminnow has suffered habitat loss and population declines due to anthropogenic habitat modifications and invasive species introductions. The lack of genetic resources for Colorado pikeminnow has hindered conservation genomic study of this unique organism. This study seeks to remedy this issue by presenting a high-quality reference genome for Colorado pikeminnow developed from Pacific Biosciences HiFi sequencing and Hi-C scaffolding. The final assembly was a 1.1 Gb genome comprised of 305 contigs including 25 chromosome-sized scaffolds. Measures of quality, contiguity, and completeness met or exceeded those observed for Danio rerio (Danionidae) and 2 other Colorado River Basin leuciscids (Meda fulgida and Tiaroga cobitis). Comparative genomic analyses identified enrichment of gene families for growth, development, immune activity, and gene transcription; all of which are important for a large-bodied piscivorous fish living in a dynamic environment. This reference genome will provide a basis for important conservation genomic study of Colorado pikeminnow and help efforts to better understand the evolution of desert fishes., Competing Interests: Conflicts of interest The author declares no conflict of interest., (Published by Oxford University Press on behalf of The Genetics Society of America 2024.)

This study was conducted to investigate the effects of recombinant Bacillus subtilis CM66-P4' (secreting P4, which related to previous research in this laboratory) on the antioxidant capacity and immune function of blunt snout bream (Megalobrama amblycephala) through in vitro and in vivo experiment. The culture experiment was divided into 3 groups, including control group (CG, with no additional bacteria), original bacteria group (OBG, with 2 × 10 9  CFU/kg Bacillus subtilis CM66) and recombinant bacteria group (RBG, with 2 × 10 9  CFU/kg Bacillus subtilis CM66-P4'). After 8 weeks of feeding, a part of the fish were subjected to fishing stress, and the rest were subjected to starvation stress test. Blood samples were collected for the determination of immune and stress-related indexes. The hepatocytes were divided into control group (CG) and experiment group with P4 peptide (LTG and HTG). The cells were collected after starvation treatment and the expression of related genes was detected. The results showed as follows: compared with the CG group, the gene expressions of hepatocytic hsp60 and hsp70 in the LTG and HTG groups were significantly suppressed after 24 h starvation stress (P < 0.05). The content of MDA, the activities of AKP and ALT in OBG group were significantly changed after 30 days starvation (P < 0.05), while the indexes in RBG group had no significant change. The changes of plasma cortisol, malondialdehyde (MDA) and Immunoglobulin M (IgM) in CG and OBG groups were significantly changed at 4 h after fishing stress (P < 0.05), while the indexes in RBG group was not. In conclusion, this study confirmed that Bacillus subtilis CM66-P4' has great potential in preventing adverse effects of stress on aquatic livestock., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Haemoglobin (HB) protein comprises four subunits: two identical α-subunits (HBA) and two identical β-subunits (HBB), encoded by the HBA and HBB genes. In this investigation, 5'/3' RACE PCR (Rapid Amplification of cDNA Ends) was used to obtain complete coding sequences (CDSs) of both the genes from farmed Labeo catla. The resulting CDSs were 432 base pairs and 447 base pairs for HBA and HBB, respectively, corresponding to 143 and 148 amino acids. Phylogenetic analysis revealed close relationships with other cyprinids, with Labeo rohita being the closest relative. Functional analysis and protein structure prediction were conducted using bioinformatics tools. Expression profiling of both genes was checked in various tissues under control (C) and hypoxic (H) conditions. Notably, under hypoxia, HBA and HBB genes were significantly upregulated (P < 0.05) initially, followed by a return to normal expression levels. Similar trends were observed for Hif1α (Hypoxia-inducible factor one alpha) and EPO (Erythropoietin) genes. Additionally, haematological indices also significantly increased corresponding to the gene expressions. However, with the decrease in the expression of these genes an onset of mortality was observed in the hypoxia (H) treated groups. The results of the current study explored the role of haemoglobin genes in adaptation to the hypoxic condition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Mitochondrial function can be regulated by ion channels. Mitochondrial RNA splicing 2 (Mrs2) is a magnesium ion (Mg 2+ ) channel located in the inner mitochondrial membrane, thereby mediating the Mg 2+ influx into the mitochondrial matrix. However, its potential role in regulating the Mg homeostasis and mitochondrial function in aquatic species is still unclear. This study molecularly characterizes the gene encoding Mrs2 in fish M. amblycephala with its functions in maintaining the Mg homeostasis and mitochondrial function verified. The mrs2 gene is 2133 bp long incorporating a 1269 bp open reading frame, which encodes 422 amino acids. The Mrs2 protein includes two transmembrane domains and a conserved tripeptide Gly-Met-Asn, and has a high homology (65.92-97.64%) with those of most vertebrates. The transcript of mrs2 was relatively high in the white muscle, liver and kidney. The inhibition of mrs2 reduces the expressions of Mg 2+ influx/efflux-related proteins, mitochondrial Mg content, and the activities of mitochondrial complex I and V in hepatocytes. However, the over-expression of mrs2 increases the expressions of Mg 2+ influx/efflux-related proteins, mitochondrial Mg content, and the complex V activity, but decreases the activities of mitochondrial complex III and IV and citrate synthase in hepatocytes. Collectively, Mrs2 is highly conserved among different species, and is prerequisite for maintaining Mg homeostasis and mitochondrial function in fish., Competing Interests: Declaration of competing interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: The genus Megalobrama holds significant economic value in China, with M. terminalis (Black Amur bream) ranking second in production within this group. However, lacking comprehensive genomic and transcriptomic data has impeded research progress. This study aims to fill this gap through an extensive transcriptomic analysis of M. terminalis., Methods and Results: We utilized PacBio Isoform Sequencing to generate 558,998 subreads, totaling 45.52 Gb, which yielded 22,141 transcripts after rigorous filtering and clustering. Complementary Illumina short-read sequencing corrected 967,114 errors across these transcripts. Our analysis identified 12,426 non-redundant isoforms, with 11,872 annotated in various databases. Functional annotation indicated 11,841 isoforms matched entries in the NCBI non-redundant protein sequences database. Gene Ontology analysis categorized 10,593 isoforms, revealing strong associations with cellular processes and binding functions. Additionally, 8203 isoforms were mapped to pathways in the Kyoto Encyclopedia of Genes and Genomes, highlighting significant involvement in immune system processes and complement cascades. We notably identified key immune molecules such as alpha-2-macroglobulin and complement component 3, each with multiple isoforms, underscoring their potential roles in the immune response. Our analysis also uncovered 853 alternative splicing events, predominantly involving retained introns, along with 672 transcription factors and 426 long non-coding RNAs., Conclusions: The high-quality reference transcriptome generated in this study provides a valuable resource for comparative genomic studies within the Megalobrama genus, supporting future research to enhance aquaculture stocks., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

This research aimed to investigate the effects of dietary fructooligosaccharides (FOS) on attenuating the Aeromonas hydrophila (A. hydrophila)-induced oxidative stress and apoptosis in blunt snout bream Megalobrama amblycephala. Fish were divided into three groups as follows: C1 (Control), T1 (A. hydrophila), and T2 (A. hydrophila + 4 g/kg FOS). The results showed that the activities of antioxidant enzymes increased, the liver morphology had disorderly arrangement, and extensive cell necrosis occurred because of A. hydrophila-infection. While the dietary FOS improved the above-mentioned liver damage. Additionaly, FOS elevated mRNA levels of pro-apoptotic molecules, including caspase-8 and 9, and down-regulated mRNA levels of the anti-apoptotic molecule Bcl-2, which is triggered by A. hydrophila-infection. The transcriptome analysis showed that the oxidative stress-related DEGs pathways were activated in intestine of blunt snout bream by A. hydrophila-infection. The FOS-added group led to the enrichment of more pathways to health. Further WGCNA co-expression network analysis showed that the screened single genes were clustered into 49 modules. The two modules with the highest association to the five traits (10 hub genes) were chosen to build the network by combining the physiological and biochemical characteristic. In summary, this research offers a foundation for the exploring of A. hydrophila-restoration genes in dietary FOS, and also lays a theoretical foundation for aquaculture in the future., (© 2024. The Author(s).)

Salinity adaptation is an important issue in aquaculture. Understanding the immediate-early response to salinity stress helps in comprehending this process. In vitro experiments using cell lines can explain cell-independent reactions without the involvement of hormones in vivo. In this study, salinity stress experiments were conducted using cell line derived from the gills of Gymnocypris przewalskii (GPG cell line) to isolate immediate-early response-related genes and miRNAs using transcriptomics, followed by bioinformatics analysis. The results showed that intracellular free Ca 2+ appeared to be a key factor in cell sensing and initiating downstream cell signaling in response to external salinity. Additionally, cell apoptosis was the most common feature of salinity stress, with multiple signaling pathways involved in salinity-induced cell apoptosis. Furthermore, MiRNAs played a crucial role in the rapid response to salinity stress by selectively inhibiting the expression of specific genes. Additionally, for the first time in the G. przewalskii genome, Tf2 and TY3 families of transposons were found to have responsive roles to the external salinity stress. This study contributes to a better understanding of osmotic sensing in G. przewalskii and provides theoretical assistance for improving salinity adaptation in aquaculture fish species., (© 2024. The Author(s).)

Background: The blunt snout bream (Megalobrama amblycephala) is an important economic freshwater fish in China with tender flesh and high nutritional value. With the cultivation of superior new varieties and the expansion of breeding scale, it becomes imperative to employ sex-control technology to cultivate monosexual populations of M. amblycephala, thereby preventing the deterioration of desirable traits. The development of specific markers capable of accurately identifying the sex of M. amblycephala would facilitate the determination of the genetic sex of the breeding population before gonad maturation, thereby expediting the processes of sex-controlled breeding of M. amblycephala., Results: A whole-genome re-sequencing was performed for 116 females and 141 males M. amblycephala collected from nine populations. Seven candidate male-specific sequences were identified through comparative analysis of male and female genomes, which were further compared with the sequencing data of 257 individuals, and finally three male-specific sequences were generated. These three sequences were further validated by PCR amplification in 32 males and 32 females to confirm their potential as male-specific molecular markers for M. amblycephala. One of these markers showed potential applicability in M. pellegrini as well, enabling males to be identified using this specific molecular marker., Conclusions: The study provides a high-efficiency and cost-effective approach for the genetic sex identification in two species of Megalobrama. The developed markers in this study have great potential in facilitating sex-controlled breeding of M. amblycephala and M. pellegrini, while also contributing valuable insights into the underlying mechanisms of fish sex determination., (© 2024. The Author(s).)

Opsariichthys bidens is an endemic minnow, mainly distributed in China as an emerging aquaculture species. In this study, O. bidens collected from Yangzte River (YR), Pearl River (PR) and Qiantang River (QR) basins were used for karyotypic study and genome sequencing. Using PacBio long reads and Hi-C data, we assembled high-quality O. bidens genomes of 852.41 Mb (YR), 843.11 Mb (PR) and 840.94 Mb (QR) with scaffold N50 lengths of 21.01 Mb, 23.62 Mb and 24.75 Mb, respectively, of which 90.39%, 95.67% and 99.01% were anchored to 37, 38 and 39 chromosomes, respectively. 26,556 (YR), 25,036 (PR) and 26,283 (QR) protein-coding genes were predicted, respectively. The karyotype of O. bidens from YR, PR and QR were 2 N = 74 (6 m + 6sm + 4st + 58t), 2 N = 76 (4 m + 6sm + 4st + 62t) and 2 N = 78 (4 m + 4sm + 4st + 66t), respectively. Collinearity analysis and telomere predictions indicated that the observed chromosomal evolution was driven by Robertsonian translocation. These genome assemblies facilitate cryptic species determination, evolutionary study and genetic breeding of genus Opsariichthys., (© 2024. The Author(s).)

A comprehensive analysis of the whole mitochondrial genomes of the Schizothoracinae subfamily of the family Cyprinidae has been revealed for the first time. The species analyzed include Schizothorax niger, Schizothorax esocinus, Schizothorax labiatus and Schizothorax plagoistomus. The total mitochondrial DNA (mtDNA) length was determined to be 16585 bp, 16583 bp, 16582 bp and 16576 bp, respectively with 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and 2 non-coding area genes. The combined mean base compositions of the four species were as follows: A: 29.91 % T: 25.47 % G: 17.65 % C 27.01 %. The range of the GC content is 45-44 %, respectively. All protein coding genes (PCGs) commenced with the typical ATG codon, except for the cytochrome c oxidase subunit 1 (COX1) gene with GTG. The analysis of vital amino acid biosynthesis genes (COX1, ATPase 6, ATPase 8) in four different species revealed no significant differences. All 13 PCGs had Ka/Ks ratios that were all lesser than one, demonstrating purifying selection on those molecules. These tRNA genes were predicted to fold into the typical cloverleaf secondary structures with normal base pairing and ranged in size from 66 to 75 nucleotides. Additionally, the phylogenetic tree analysis revealed that S. esocinus species that was most alike to S. labiatus. This study provides critical data for phylogenetic analysis of the Schizothoracinae subfamily, which will help to resolve taxonomic difficulties and identify evolutionary links. Detailed mtDNA data are an invaluable resource for studying genetic diversity, population structure, and gene flow. Understanding genetic makeup can help inform conservation plans, identify unique populations, and track genetic variation to ensure effective preservation., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflict of interest to disclose., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The Deccan mahseer, Tor khudree (Sykes 1839), belonging to family Cyprinidae is an important food and a game fish distributed in peninsular India. Due to overfishing and habitat destruction, the species is declared endangered and placed on the IUCN red list. Therefore, a well-designed conservation program may be essential to get this species protected in its natural habitat. We used a total of 152 samples from four rivers of peninsular India to assess the genetic diversity and structure of the mahseer using concatenated sequences of two mitochondrial genes, ATPase 6/8 (790 bp) and Cyt b (1000 bp). High haplotypic diversity was seen with 44 haplotypes. Individual gene wise haplotypes included 10 and 21 haplotypes for ATPase6/8 and Cyt b, respectively. AMOVA revealed most of the genetic variations (71.02%) to be within the populations. Significant genetic differentiation was observed between all population pairs, with FST values ranging from 0.121 to 0.372, with minimum between Tunga and Tungabhadra population and maximum between Tunga and Periyar population. Haplotype network showed one ancestral haplotype (TKACH04). Significant negative Fu's F and unimodal mismatch distribution suggested recent demographic expansion. The results of the present study would serve as a useful resource for further research on population genetics and conservation programs of the species., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Polymeric immunoglobulin receptor (pIgR) is an important immune factor in the mucosal immune system of fish, which plays a key role in mediating the secretion and transport of immunoglobulin into mucus. In this study, the full-length cDNA sequence of Megalobrama amblycephala pIgR gene was firstly cloned and the immune response to Aeromonas hydrophila was detected. After being challenged by Aeromonas hydrophila at 3 d, significantly pathological features were observed in intestine, head kidney, spleen, liver and gill of Megalobrama amblycephala. The content of lysozyme (Lys) and the activities of acid phosphatase (ACP) and alkaline phosphatase (AKP) increased significantly at 1 d and reached the peak at 3 d, and the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) in serum reached the peak at 5 d and 7 d after infection, respectively. The expression level of IL-1β gene reached the peak at 3 d in intestine, 5 d in gill and spleen, 7 d in head kidney and liver of Megalobrama amblycephala after infected by Aeromonas hydrophila, respectively. The TNF-α gene expression reached the peak at 3 d in intestine and gill, 5 d in head kidney and spleen, 7 d in liver after infection, respectively. The experimental results showed that the infection of Aeromonas hydrophila caused the pathological changes of immune-related tissues and triggered the inflammation responses. The full-length cDNA sequence of Megalobrama amblycephala pIgR was 1828 bp, and its open reading frame (ORF) was 1023 bp, encoding 340 amino acids. The pIgR of Megalobrama amblycephala has a signal peptide sequence, followed by extracellular region, transmembrane region and intracellular region. The extracellular region includes two Ig-like domains (ILDs), and its tertiary structure is twisted "L". The phylogenetic tree was constructed using the adjacency method, and the pIgR genes of Megalobrama amblycephala and cyprinidae fish were clustered into a single branch. Quantitative real-time PCR (qRT-PCR) was used to detect the expression of pIgR gene in different tissues of Megalobrama amblycephala. The expression level of pIgR gene was the highest in liver, followed by intestine, head kidney, skin, middle kidney and spleen, lower in heart, gill and brain, and the lowest in muscle. After being infected by Aeromonas hydrophila, the expression level of Megalobrama amblycephala pIgR gene in intestine, head kidney, spleen, liver and gill showed a trend of increasing first and then decreasing within 28 d. The pIgR gene expression reached the peak in mucosal immune-related tissues (gill and intestine) was earlier than that in systemic immune-related tissues (head kidney and spleen), and the relative expression level of pIgR gene at peak in intestine (12.3 fold) was higher than that in head kidney (3.73 fold) and spleen (7.84 fold). These results suggested that Megalobrama amblycephala pIgR might play an important role in the mucosal immune system to against Aeromonas hydrophila infection., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Leuciscus merzbacheri is a rare and endangered fish in Xinjiang, China. As a representative species of the fauna in the Junggar Basin, it is of high economic and scientific value. The genetic data are still limited, and the mitochondrial genomic characteristics remain unexplored., Methods: A high-throughput sequencing method was used to obtain the complete mitogenome of L. merzbacheri ., Results: The full length of the circular DNA was 16,609 bp, and it consisted of 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNAs and 2 non-coding regions. The overall nucleotide compositions of both the mitogenome and PCGs showed an obvious AT preference with percentages of 54.20% and 53.60%, respectively. Three commonly used amino acids were Leu (16.43%), Ala (8.95%) and Thr (7.85%) in turn. All tRNAs could form the typical clover structures excluding tRNA-Ser AGY . The presumed secondary structures of two rRNAs contained several stem-loop domains, and the structure of 12S rRNA seemed to be more stable than that of 16S rRNA. Extended termination sequence regions (ETASs), central conserved regions (CSB-F, CSB-E and CSB-D), and conserved sequence regions (CSB-1, CSB-2 and CSB-3) were identified in the control region. The phylogenetic tree showed that L. merzbacheri was recovered with strong supports as a sister to the other members of the genus. The location in the outermost branch implied that it might be a relatively ancient species among its congeners., Conclusions: This study would complement the genetic data on L. merzbacheri and contribute to a better understanding of molecular evolution in Leuciscus as well.

The hybrid F 1 offspring of Ctenopharyngodon idella (♂) and Squaliobarbus curriculus (♀) exhibit heterosis in disease resistance and also show abnormal sex differentiation. To understand the mechanism behind gonadal differentiation in the hybrid F 1 , we analyzed the transcriptomes of C. idella , S. curriculus , and the hybrid F 1 ; screened for genes related to gonad development in these samples; and measured their expression levels. Our results revealed that compared to either C. idella or S. curriculus , the gene expressions in most sub-pathways of the SNARE interactions in the vesicular transport pathway in the hypothalamus, pituitary, and gonadal tissues of their hybrid F 1 offspring were significantly up-regulated. Furthermore, insufficient transcription of genes involved in oocyte meiosis may be the main reason for the insufficient reproductive ability of the hybrid F 1 offspring. Through transcriptome screening, we identified key molecules involved in gonad development, including HSD3B7, HSD17B1, HSD17B3, HSD20B2, CYP17A2, CYP1B1, CYP2AA12, UGT2A1, UGT1A1, and FSHR, which showed significant differences in expression levels in the hypothalamus, pituitary, and gonads of these fish. Notably, the expression levels of UGT1A1 in the gonads of the hybrid F 1 were significantly higher than those in C. idella and S. curriculus . These results provide a scientific basis for further research on the gonadal differentiation mechanism of hybrid F 1 offspring.

Fishes from the genus Carasobarbus, widely distributed throughout the river systems of North Africa and West Asia, are commonly referred to as Himris. In the Persian Gulf basin, they are widespread and are also found in fast-flowing rivers or the deeper regions of lakes. In this region, representation of these fishes in scientific collections is scarce, and except for C. luteus, the other species are very poorly documented and frequently misidentified due to their similarities. In this study we analysed the relationships among Carasobarbus species using mitochondrial genes (Cyt b, COI) and present morphological characters based on examinations. Our results revealed three new species which we describe here. Carasobarbus doadrioi, new species, is distinguished by 40-44 scales on the lateral line and a prominent black blotch on end of caudal peduncle in specimens < 85 mm SL. Carasobarbus hajhosseini, new species is distinguished by 32-34 scales on the lateral line and long head length (20-24% SL). Carasobarbus saadatii, new species, is distinguished by 38-40 scales on the lateral line and short head length (19-20% HL). In the Persian Gulf basin, Carasobarbus species exhibit uncorrected genetic distances of 1.6 to 5.5% in the COI barcode region and 2.6% to 9.9% in the Cyt b gene. This study highlights the importance of investigating the unexplored diversity that exists within poorly sampled and understudied freshwater fish group. Such investigations are essential for developing a comprehensive understanding of the true extent of biodiversity, which is critical for informing effective conservation and protection strategies., (© 2024. The Author(s).)

Freshwater salinization is an escalating global environmental issue that threatens freshwater biodiversity, including fish populations. This study aims to uncover the molecular basis of salinity physiological responses in a non-native minnow species (Phoxinus septimaniae x P. dragarum) exposed to saline effluents from potash mines in the Llobregat River, Barcelona, Spain. Employing high-throughput mRNA sequencing and differential gene expression analyses, brain, gills, and liver tissues collected from fish at two stations (upstream and downstream of saline effluent discharge) were examined. Salinization markedly influenced global gene expression profiles, with the brain exhibiting the most differentially expressed genes, emphasizing its unique sensitivity to salinity fluctuations. Pathway analyses revealed the expected enrichment of ion transport and osmoregulation pathways across all tissues. Furthermore, tissue-specific pathways associated with stress, reproduction, growth, immune responses, methylation, and neurological development were identified in the context of salinization. Rigorous validation of RNA-seq data through quantitative PCR (qPCR) underscored the robustness and consistency of our findings across platforms. This investigation unveils intricate molecular mechanisms steering salinity physiological response in non-native minnows confronting diverse environmental stressors. This comprehensive analysis sheds light on the underlying genetic and physiological mechanisms governing fish physiological response in salinity-stressed environments, offering essential knowledge for the conservation and management of freshwater ecosystems facing salinization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This study confirms the extended distribution of two invasive species of the genus Ameiurus in Ukraine. Specifically, A. melas is recorded for the first time in the Southern Buh basin and A. nebulosus has expanded further eastward within the Dnipro basin. Material collected in 2019 and 2022 was identified by morphological features and confirmed by molecular genetic analysis. The most reliable morphological characters for distinguishing these two species include anal-fin membrane pigmentation (light or black), gill raker count (fewer or more than 16), and serrations on the pectoral-fin spine (well-developed along the full length or small, absent near the tip). The analysis of the cytochrome oxidase subunit I barcoding marker identified all samples from the Dnipro Basin (Tnia and Velykyi Luh localities) as A. nebulosus, while all specimens from the Vinnytsia region within the Southern Buh basin (Sotskoho and Vyshenske lakes) were attributed to A. melas. The maximum-likelihood analysis revealed clearly separated clades with high bootstrap support (>75%), strongly supporting the presence of the two separate species. This study suggests the potential for further eastward expansion of both species within Ukraine: A. nebulosus in the northern direction and A. melas in the southern direction., (© 2024 Fisheries Society of the British Isles.)

Gene regulatory networks (GRNs) are crucial for understanding organismal molecular mechanisms and processes. Construction of GRN in the epithelioma papulosum cyprini (EPC) cells of cyprinid fish by spring viremia of carp virus (SVCV) infection helps understand the immune regulatory mechanisms that enhance the survival capabilities of cyprinid fish. Although many computational methods have been used to infer GRNs, specialized approaches for predicting the GRN of EPC cells following SVCV infection are lacking. In addition, most existing methods focus primarily on gene expression features, neglecting the valuable network structural information in known GRNs. In this study, we propose a novel supervised deep neural network, named MEFFGRN (Matrix Enhancement- and Feature Fusion-based method for Gene Regulatory Network inference), to accurately predict the GRN of EPC cells following SVCV infection. MEFFGRN considers both gene expression data and network structure information of known GRN and introduces a matrix enhancement method to address the sparsity issue of known GRN, extracting richer network structure information. To optimize the benefits of CNN (Convolutional Neural Network) in image processing, gene expression and enhanced GRN data were transformed into histogram images for each gene pair respectively. Subsequently, these histograms were separately fed into CNNs for training to obtain the corresponding gene expression and network structural features. Furthermore, a feature fusion mechanism was introduced to comprehensively integrate the gene expression and network structural features. This integration considers the specificity of each feature and their interactive information, resulting in a more comprehensive and precise feature representation during the fusion process. Experimental results from both real-world and benchmark datasets demonstrate that MEFFGRN achieves competitive performance compared with state-of-the-art computational methods. Furthermore, study findings from SVCV-infected EPC cells suggest that MEFFGRN can predict novel gene regulatory relationships., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Monogeneans of the genus Dactylogyrus Diesing, 1850, the largest genus in the family Dactylogyridae, mostly parasitize the gills of cyprinoid hosts; however, only 3 Dactylogyrus' mitochondrial genomes (mitogenomes) are studied so far. The aim of this research is to extend our understanding of the mitogenomes of Dactylogyrus. We sequenced the mitogenomes of D. crucifer and D. zandti isolated from Rutilus rutilus and Abramis brama orientalis in northwest China, and then we compared these mitogenomes with other monogeneans. We used Illumina NovaSeq to sequence the entire mitochondrial genomes of D. crucifer and D. zandti and characterized the mitogenomes to understand the gene structure, gene identity, the secondary structures of the 22 tRNA genes, and relative synonymous codon usage. We used the analytic Bayesian Information and Maximum Likelihood methods to determine their associated phylogenetic trees. The mitogenomes of D. crucifer and D. zandti were 14,403 and 18,584 bp, respectively. Organization and positioning of these genes were in accordance with Dactylogyrus lamellatus and Dactylogyrus tuba. The nucleotide composition of Dactylogyridae was different from other families of Monogenea, and the A+T count of genus Dactylogyrus (54 - 58.4 %) was lower than other genus species of the family Dactylogyridea (63.9 - 78.4 %) in protein-coding genes. Dactylogyrus members displayed a codon usage bias. The relative synonymous codon used by Dactylogyrus was not conserved and was lower than other monogeneans. The codon use patterns of closely-related species isolated from closely-related hosts were identical. Phylogenetic analyses using mitogenomic dataset produced Dactylogyrus isolated from host subfamily Leuciscinae formed a sister-group. Our results contributed significantly to an increased database of mitogenomes, more than 50 %, for Dactylogyrus that may help future studies of mitochondrial genes and codon uses for the analysis of monogenean phylogenetics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Culter alburnus is extensively distributed in various rivers and lakes across China. As a widely adaptive fish species, it has significant economic values and special ecological roles. To meet research demands and provide better genomic resources, in this research, a chromosome-level genome assembly was constructed using HiFi long-reads and Hi-C sequencing data. Compared with the published versions, our genome assembly is of higher quality with only 31 gaps and closer to its true structure and sequence. The genome size was 1.052 Gb, with a contig N50 of 32.92 Mb and a scaffold N50 of 43.09 Mb. 55 contigs were anchored to 24 chromosomes on the basis of Hi-C data. A total of 598.23 Mb of repetitive sequences were annotated and 28,228 protein-coding genes were predicted. Additionally, BUSCO assessment indicated assembly and annotation scores of 98.3% and 99.2%, respectively. This high-quality genome will provide scientific support for excavating the species characteristics of C. alburnus and exploring its molecular mechanisms in response to environmental changes and stress., (© 2024. The Author(s).)

Background: Captive breeding, along with artificial selection can significantly impact population structure by influencing allele frequencies and driving populations towards specific adaptation. Selective sweeps are powerful forces in shaping genetic variation within populations and can drive rapid spread of beneficial alleles while simultaneously reducing genetic diversity in localized regions of the genome. The present work was undertaken to assess the genetic structure and consequences of artificial selection in 10 th generation of genetically improved rohu by comparing with wild populations., Methods and Results: The present study used 11,022 high-quality genome wide SNPs to compare the population genetic structure and signatures of selection between Jayanti rohu population and its wild counterpart. Outlier analysis revealed presence of 14 adaptive SNPs, out of which 5 were classified to be under decisive selection pressure. Notably, Jayanti rohu (JR) displayed 297 private alleles exclusive to its population. Chromosomes 7 and 16 emerged as potential hotspots containing a majority of the identified SNPs. Structure and principal component analysis revealed two distinct clusters, effectively distinguishing the JR and wild rohu populations. Phylogenetic analysis indicated a separate cluster of JR population distant from wild groups., Conclusion: The results of present study shall help in elucidating patterns of genetic variation and characterizing selection signatures associated with captive bred and natural populations of rohu. The genomic resources generated through this work shall be helpful in improving the traceability of selectively bred germplasm for developing future strategies of genetic management., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The present study, as one part of a larger project that aimed to investigate the effects of dietary berberine (BBR) on fish growth and glucose regulation, mainly focused on whether miRNAs involve in BBR's modulation of glucose metabolism in fish. Blunt snout bream Megalobrama amblycephala (average weight of 20.36 ± 1.44 g) were exposed to the control diet (NCD, 30% carbohydrate), the high-carbohydrate diet (HCD, 43% carbohydrate) and the berberine diet (HCB, HCD supplemented with 50 mg/kg BBR). After 10 weeks' feeding trial, intraperitoneal injection of glucose was conducted, and then, the plasma and liver were sampled at 0 h, 1 h, 2 h, 6 h, and 12 h. The results showed the plasma glucose levels in all groups rose sharply and peaked at 1 h after glucose injection. Unlike the NCD and HCB groups, the plasma glucose in the HCD group did not decrease after 1 h, while remained high level until at 2 h. The NCD group significantly increased liver glycogen content at times 0-2 h compared to the other two groups and then liver glycogen decreased sharply until at times 6-12 h. To investigate the role of BBR that may cause the changes in plasma glucose and liver glycogen, miRNA high-throughput sequencing was performed on three groups of liver tissues at 2 h time point. Eventually, 20 and 12 differentially expressed miRNAs (DEMs) were obtained in HCD vs NCD and HCB vs HCD, respectively. Through function analyzing, we found that HCD may affect liver metabolism under glucose loading through the NF-κB pathway; and miRNAs regulated by BBR mainly play roles in adipocyte lipolysis, niacin and nicotinamide metabolism, and amino acid transmembrane transport. In the functional exploration of newly discovered novel:Chr12&#95;18892, we found its target gene, adenylate cyclase 3 (adcy3), was widely involved in lipid decomposition, amino acid metabolism, and other pathways. Furthermore, a targeting relationship of novel:Chr12&#95;18892 and adcy3 was confirmed by double luciferase assay. Thus, BBR may promote novel:Chr12&#95;18892 to regulate the expression of adcy3 and participate in glucose metabolism., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Interleukin-10 (IL-10) is an immunosuppressive cytokine, which plays a vital role in regulating inflammation for inhibiting the generation and function of pro-inflammatory cytokines in vivo or in vitro. In the present study, the full length cDNA of IL-10 was characterized from Nibea albiflora (named as NaIL-10) of 1238 base pairs (bp), containing a 5'-UTR (untranslated region) of 350 bp, a 3'-UTR of 333 bp and an open reading frame (ORF) of 555 bp (Fig. 1A) to encode 184 amino acid residues with a signal peptide at the N-terminus. The sequence analysis showed that NaIL-10 possessed the typical IL-10 family symbolic motif and conversed cysteine residues, similar to its teleost orthologues. Real-time PCR indicated that NaIL-10 had wide distribution in different healthy tissues, with a relatively high expression in immune-related tissues (head kidney, spleen, kidney, liver and gill). Significantly, up-regulations of NaIL-10 after infection against Vibrio parahaemolyticus, Vibrio alginolyticus and Poly I:C were also observed. Subcellular localization manifested that NaIL-10 mainly distributed in the cytoplasm unevenly and aggregately, and there was also a small amount on the cell membrane, indicating that NaIL-10 was secreted to the extracellular space as the known IL-10 homologous molecules. It could co-locate with IL-10 Rα on the membrane of HEK293T cells for their potential interaction, and GST pull-down and Co-IP studies certified the specific and direct interaction between NaIL-10 and NaIL-10 Rα, confirming that an IL-10 ligand-receptor system existed in N.albiflora. The expression of pro-inflammatory cytokines, including TNF-α, IL-6, IL-1β, were dramatically inhibited in LPS-stimulated RAW264.7 macrophages pre-incubated with recombinant NaIL-10 protein, demonstrating its anti-inflammatory roles. Taken together, the results demonstrated the existence of IL-10 ligand-receptor system in N.albiflora for the first time, and indicated the suppressive function of NaIL-10 on pro-inflammatory cytokine expression in inflammatory response, which would be conducive to better comprehending the role of IL-10 in the immunomodulatory mechanisms of teleost., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

As the global aquaculture industry grows, attention is increasingly turning towards assisted reproductive technologies. In this study, we examined the impact of D-Ala6, Pro9-Net-mGnRH (LHRHa: 0.4 mL/kg) and two doses (1 and 10 μg/kg fish) of thyroxin (T4) administered through a single injection on oocyte maturation, spawning performance, sex steroid hormone levels, as well as the expression of genes related to steroidogenesis and follicle development (ZP2, Cyp19a1a and SF-1) in Rohu (Labeo rohita). The study found that untreated female Rohu did not spawn, while those treated with LHRHa and thyroxin ovulated and spawned across a hormonal gradient. The highest spawning success was observed with a thyroxin dosage of 10 µg/kg (no significant change with a dose of 1 μg/kg), and female latency period decreased with increasing dosage. Additionally, females treated with thyroxin exhibited significantly higher fecundity than other experimental groups. Treatment with LHRHa and two doses of thyroxin significantly increased the gonadal somatic index compared to the control and sham groups. Hormonal treatment also led to increased fertilization success, hatching rate, and larval survival. At 12 h post-injection, females treated with thyroxin exhibited a significant decline in estradiol levels and expression of Zp2, Cyp19a1a, and SF-1 compared to other experimental groups. Levels of DHP significantly increased across the hormonal gradient. Histological analyses supported a steroidogenic shift, where oocyte maturation was accelerated by hormone administration, particularly with both doses of thyroxin. In conclusion, the findings suggest that thyroxin is a recommended treatment for assisted reproduction of Rohu due to its ability to induce spawning, increase fecundity and improve larval survival., Competing Interests: Declaration of Competing Interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The colonization of a novel geographic area is a classic source of ecological opportunity. Likewise, complex microhabitats are thought to promote biodiversity. We sought to reconcile these two predictions when they are naturally opposing outcomes. We assess the macroevolutionary consequences of an ancestral shift from benthic to pelagic microhabitat zones on rates of speciation and phenotypic evolution in North American minnows. Pelagic species have more similar phenotypes and slower rates of phenotypic evolution, but faster speciation rates, than benthic species. These are likely two independent, opposing responses to specialization along the benthic-pelagic axis, as rates of phenotypic evolution and speciation are not directly correlated. The pelagic zone is more structurally homogenous and offers less ecological opportunity, acting as an ecological dead end for minnows. In contrast, pelagic species may be more mobile and prone to dispersal and subsequent geographic isolation and, consequently, experience elevated instances of allopatric speciation. Microhabitat shifts can have decoupled effects on different dimensions of biodiversity, highlighting the need for nuance when interpreting the macroevolutionary consequences of ecological opportunity., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE). All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Hypoxia is a common environmental stressor in aquatic ecosystems, and during the cultivation process, Megalobrama amblycephala is prone to death because it is hypoxia-intolerant, which brings huge economic losses to farmers. The pituitary gland is a crucial endocrine gland in fish, and it is mainly involved in the secretion, storage, and regulation of hormones. In the present study, we compared the transcriptional responses to serious hypoxia in the pituitary gland among hypoxia-sensitive (HS) and hypoxia-tolerant (HT) M. amblycephala and a control group that received a normal oxygen supply (C0). The fish were categorized according to the time required to lose balance during a hypoxia treatment. A total of 129,251,170 raw reads were obtained. After raw sequence filtering, 43,461,745, 42,609,567, and 42,730,282 clean reads were obtained for the HS, HT, and C0 groups, respectively. A transcriptomic comparison revealed 1234 genes that were differentially expressed in C0 vs. HS, while 1646 differentially expressed genes were obtained for C0 vs. HT. In addition, the results for HS vs. HT showed that 367 upregulated and 41 downregulated differentially expressed genes were obtained for a total of 408 differentially expressed genes. A KEGG analysis of C0 vs. HS, C0 vs. HT, and HS vs. HT identified 315, 322, and 219 enriched pathways, respectively. Similar hypoxia-induced transcription patterns suggested that the downregulated DEGs and enriched pathways were related to pathways of neurodegeneration in multiple diseases, pathways in cancer, thermogenesis, microRNAs in cancer, diabetic cardiomyopathy, and renin secretion. However, in the upregulated DEGs, the PI3K-Akt signaling pathway (C0 vs. HS), microRNAs in cancer (C0 vs. HT), and HIF-1 signaling pathway (HS vs. HT) were significantly enriched. There is a lack of clarity regarding the role of the pituitary gland in hypoxic stress. These results not only provide new insights into the mechanism by which pituitary tissue copes with hypoxia stress in M. amblycephala but also offer a basis for breeding M. amblycephala with hypoxia-resistant traits.

Plagiognathops microlepis is an economic freshwater fish in the subfamily Xenocyprinae of Cyprinidae. It is widely distributed in the freshwater ecosystem of China, with moderate economic value and broad development prospects. However, the lack of genomic resources has limited our understanding on the genetic basis, phylogenetic status and adaptive evolution strategies of this fish. Here, we assembled a chromosome-level reference genome of P. microlepis by integrating Pacbio HiFi long-reads, Illumina short-reads and Hi-C sequencing data. The size of this genome is 1004.34 Mb with a contig N50 of 38.80 Mb. Using Hi-C sequencing data, 99.59% of the assembled sequences were further anchored to 24 chromosomes. A total of 578.91 Mb repeat sequences and 28,337 protein-coding genes were predicted in the current genome, of which, 26,929 genes were functionally annotated. This genome provides valuable information for investigating the phylogeny and evolutionary history of cyprinid fishes, as well as the genetic basis of adaptive strategies and special traits in P. microlepis., (© 2024. The Author(s).)

The family Cyprinidae is the largest freshwater fish group with 377 genera and over 3,000 described species. However, this group of fish has very limited cytogenetics and advanced molecular cytogenetics information. Therefore, in this study the karyotypes and other chromosomal characteristics of 15 species in the tribe Systomini (Cyprininae) were examined using Ag-NOR staining along with fluorescence in situ hybridization (5S and 18S rDNA). All species share a similar karyotype (2n = 50; NF = 88-100) in both sexes and no differentiated sex chromosome was observed. Chromosomes bearing NOR sites ranged from one to four pairs among the species, mostly mapped adjacent to telomeres in the short arms of distinct pairs in all analyzed species. This difference indicates an extensive rearrangement of chromosomes including genomic differences. The use of the 5S and 18S rDNA probe confirmed the Ag-NOR sites interstitially located in the telomeric regions of distinct chromosomes, characterizing an interspecies variation of these sites. In most of its analyzed species, the signals of 18S rDNA probe corresponded to the Ag-NOR regions, except in Barbonymus altus, B. gonionotus, B. schwanenfeldii and Puntius brevis having these signals on the same as Ag-NOR regions and other sites., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Buasriyot et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The hemicultrine fishes are a group of small-sized cyprinids, widely distributed but endemic to East Asian rivers and lakes. Till now, the taxonomic boundaries and relationships within this group remain poorly explored. In the present study, we study the phylogeny of this group, providing suggestions for classification of the hemicultrine group. Using two mitochondrial and three nuclear genes, and samples representing all genera, our results showed that the group consists of seven major lineages, of which four (Hemiculterella, Hainania, Pseudolaubuca, and Anabarilius) were monophyletic and three (Hemiculter, Toxabramis, and Pseudohemiculter) were not. Based on the phylogenetic tree, we redefined the genera. We revive the genus Siniichthys, which has three species, Siniichthys bleekeri, Siniichthys lucidus, and S. varpachovskii, that were previously treated as members of the genus Hemiculter but showed distant relationships to the genus Hemiculter in our phylogenetic tree. With the new results, a diagnostic key for clades of the hemicultrine group is provided. Furthermore, we provide more detailed information on diagnostic features of the recently described species Hemiculter yungaoi (Vasil'eva et al., 2022). This work will facilitate future systematic studies, pave the way for evolutionary studies, and provide valuable information for the urgent conservation of hemicultrine fishes., (© 2024 Fisheries Society of the British Isles.)

The present drainage network of Bulgaria is the result of a complex Neogene and Quaternary evolution. Karst, which has developed on 23% of the territory, further complicates the hydrological pattern. Fresh waters of Bulgaria drain into the Black Sea and the Aegean Sea basins and can be roughly divided into the Danube (Middle and Lower Danube), non-Danube Black Sea, East Aegean, and West Aegean hydrological regions. Phoxinus, a small leuciscid fish, has a mosaic distribution in all four of these regions, inhabiting small mountainous and semi-mountainous streams. Based on morphology, it was identified as three species, Phoxinus phoxinus in the Danube, Phoxinus strandjae in the non-Danube, and Phoxinus strymonicus in West Aegean region. Later, molecular data revealed Phoxinus csikii and Phoxinus lumaireul in the Middle Danube and P. csikii in the Lower Danube. Phoxinus has been the focus of many studies, showing a high molecular and morphological diversity, which is not entirely consistent with previous morphology-only-based taxonomic concepts. In this study, molecular (a mitochondrial marker and a nuclear marker) and morphological data from both historical and recently sampled collections were analysed to assess the applicability of the integrative approach in Phoxinus. The results showed a significant influence of the complex paleo- and recent hydrology on the currently observed genetic structure of the considered populations and species. Furthermore, the study also demonstrated a strong influence of phenotypic plasticity on the morphological analysis of Phoxinus and the lack of a clear differentiation between P. csikii and P. strandjae. A barcoded specimen was designated as neotype to fix the species named P. strandjae in the current taxonomic concept. Finally, a significant discordance between genetically delimited clades and phenotypic groups did not allow a proper delineation of the species distributed in Bulgaria, demonstrating that more molecular markers are needed for further taxonomic study of the Phoxinus complex., (© 2024 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

The role of phenotypic plasticity during colonization remains unclear due to the shifting importance of plasticity across timescales. In the early stages of colonization, plasticity can facilitate persistence in a novel environment; but over evolutionary time, processes such as genetic assimilation may reduce variation in plastic traits such that species with a longer evolutionary history in an environment can show lower levels of plasticity than recent invaders. Therefore, comparing species in the early stages of colonization to long-established species provides a powerful approach for uncovering the role of phenotypic plasticity during different stages of colonization. We compared gene expression between low-dissolved oxygen (DO) and high-DO populations of two cyprinid fish: Enteromius apleurogramma, a species that has undergone a recent range expansion, and E. neumayeri, a long-established native species in the same region. We sampled tissue either immediately after capture from the field or after a 2-week acclimation under high-DO conditions, allowing us to test for both evolved and plastic differences in low-DO vs high-DO populations of each species. We found that most genes showing candidate-evolved differences in gene expression did not overlap with those showing plastic differences in gene expression. However, in the genes that did overlap, there was counter-gradient variation such that plastic and evolved gene expression responses were in opposite directions in both species. Additionally, E. apleurogramma had higher levels of plasticity and evolved divergence in gene expression between field populations. We suggest that the higher level of plasticity and counter-gradient variation may have allowed rapid genetic adaptation in E. apleurogramma and facilitated colonization. This study shows how counter-gradient variation may impact the colonization of divergent oxygen environments., (© 2024 The Author(s). Molecular Ecology published by John Wiley & Sons Ltd.)

Background: Viperin, also known as radical S-adenosyl-methionine domain containing protein 2 (RSAD2), is an interferon-inducible protein that is involved in the innate immune response against a wide array of viruses. In mammals, Viperin exerts its antiviral function through enzymatic conversion of cytidine triphosphate (CTP) into its antiviral analog ddhCTP as well as through interactions with host proteins involved in innate immune signaling and in metabolic pathways exploited by viruses during their life cycle. However, how Viperin modulates the antiviral response in fish remains largely unknown., Results: For this purpose, we developed a fathead minnow (Pimephales promelas) clonal cell line in which the unique viperin gene has been knocked out by CRISPR/Cas9 genome-editing. In order to decipher the contribution of fish Viperin to the antiviral response and its regulatory role beyond the scope of the innate immune response, we performed a comparative RNA-seq analysis of viperin -/- and wildtype cell lines upon stimulation with recombinant fathead minnow type I interferon., Conclusions: Our results revealed that Viperin does not exert positive feedback on the canonical type I IFN but acts as a negative regulator of the inflammatory response by downregulating specific pro-inflammatory genes and upregulating repressors of the NF-κB pathway. It also appeared to play a role in regulating metabolic processes, including one carbon metabolism, bone formation, extracellular matrix organization and cell adhesion., (© 2024. The Author(s).)

Introduction: STAT1a is an essential signal transduction protein involved in the interferon pathway, playing a vital role in IFN-alpha/beta and gamma signaling. Limited information is available about the STAT protein in fish, particularly in Indian major carps (IMC). This study aimed to identify and characterize the STAT1a protein in Labeo rohita (LrSTAT1a)., Methods: The full-length CDS of LrSTAT1a transcript was identified and sequenced. Phylogenetic analyses were performed based on the nucleotide sequences. The in-vivo immune stimulant poly I: C was used to treat various tissues, and the expression of LrSTAT1a was determined using quantitative real-time polymerase chain reaction (qRT-PCR). A 3D model of the STAT1a protein was generated using close structure homologs available in the database and checked using molecular dynamics (MD) simulations., Results: The full-length CDS of Labeo rohita STAT1a ( LrSTAT1a ) transcript consisted of 3238 bp that encoded a polypeptide of 721 amino acids sequence was identified. Phylogenetic analyses were performed based on the nucleotide sequences. Based on our findings, other vertebrates share a high degree of conservation with STAT1a . Additionally, we report that the in vivo immune stimulant poly I: C treatment of various tissues resulted in the expression of LrSTAT1a as determined by quantitative real-time polymerase chain reaction (qRT-PCR). In the current investigation, treatment with poly I: C dramatically increased the expression of LrSTAT1a in nearly every organ and tissue, with the brain, muscle, kidney, and intestine showing the highest levels of expression compared to the control. We made a 3D model of the STAT1a protein by using close structure homologs that were already available in the database. The model was then checked using molecular dynamics (MD) simulations. Consistent with previous research, the MD study highlighted the significance of the STAT1a protein, which is responsible for Src homology 2 (SH2) recognition. An important H-bonding that successfully retains SH2 inside the STAT1a binding cavity was determined to be formed by the conserved residues SER107, GLN530, SER583, LYS584, MET103, and ALA106., Discussion: This study provides molecular insights into the STAT1a protein in Rohu ( Labeo rohita ) and highlights the potential role of STAT1a in the innate immune response in fish. The high degree of conservation of STAT1a among other vertebrates suggests its crucial role in the immune response. The in-vivo immune stimulation results indicate that STAT1a is involved in the immune response in various tissues, with the brain, muscle, kidney, and intestine being the most responsive. The 3D model and MD study provide further evidence of the significance of STAT1a in the immune response, specifically in SH2 recognition. Further research is necessary to understand the specific mechanisms involved in the IFN pathway and the role of STAT1a in the immune response of IMC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Das, Panda, Pradhan, Raut, Kumari and Meena.)

Acrossocheilus fasciatus is a stream-dwelling fish species of the Barbinae subfamily. It is valued for its colorfully striped appearance and delicious meat. This species is also characterized by apparent sexual dimorphism and toxic ovum. Biology and aquaculture researches of A. fasciatus are hindered by the lack of a high-quality reference genome. Here, we report chromosome-level genome assemblies of the male and female A. fasciatus. The HiFi-only genome assemblies for both female and male individuals were 899.13 Mb (N50 length of 32.58 Mb) and 885.68 Mb (N50 length of 33.06 Mb), respectively. Notably, a substantial proportion of the assembled sequences, accounting for 96.15% and 98.35% for female and male genomes, respectively, were successfully anchored onto 25 chromosomes utilizing Hi-C data. We annotated the female assembly as a reference genome and identified a total of 400.62 Mb (44.56%) repetitive sequences, 27,392 protein-coding genes, and 35,869 ncRNAs. The high-quality male and female reference genomes will provide genomic resources for developing sex-specific molecular markers, inform single-sex breeding, and elucidate genetic mechanisms of sexual dimorphism., (© 2024. The Author(s).)

This study is the first report to characterize the Rhodus uyekii genome and study the development of microsatellite markers and their markers applied to the genetic structure of the wild population. Genome assembly was based on PacBio HiFi and Illumina HiSeq paired-end sequencing, resulting in a draft genome assembly of R. uyekii . The draft genome was assembled into 2652 contigs. The integrity assessment of the assemblies indicates that the quality of the draft assemblies is high, with 3259 complete BUSCOs (97.2%) in the database of Verbrata. A total of 31,166 predicted protein-coding genes were annotated in the protein database. The phylogenetic tree showed that R. uyekii is a close but distinct relative of Onychostoma macrolepis . Among the 10 fish genomes, there were significant gene family expansions (8-2387) and contractions (16-2886). The average number of alleles amplified by the 21 polymorphic markers ranged from 6 to 23, and the average PIC value was 0.753, which will be useful for evolutionary and genetic analysis. Using population genetic analysis, we analyzed genetic diversity and the genetic structures of 120 individuals from 6 populations. The average number of alleles per population ranged from 7.6 to 9.9, observed heterozygosity ranged from 0.496 to 0.642, and expected heterozygosity ranged from 0.587 to 0.783. Discriminant analysis of principal components According to the analysis method, the population was divided into three populations (BS vs. DC vs. GG, GC, MS, DC). In conclusion, our study provides a useful resource for comparative genomics, phylogeny, and future population studies of R. uyekii .

Background: Interspecific hybrids of rohu (Labeo rohita) and catla (Labeo catla) are common, especially in India due to constrained breeding. These hybrids must segregate from their wild parents as part of conservational strategies. This study intended to screen the hybrids from wild rohu and catla parents using both morphometric and molecular approaches., Methods & Results: The carp samples were collected from Jharkhand and West Bengal, India. The correlation and regression analysis of morphometric features are considered superficial but could be protracted statistically by clustering analysis and further consolidated by nucleotide variations of one mitochondrial and one nuclear gene to differentiate hybrids from their parents. Out of 21 morphometric features, 6 were used for clustering analysis that exhibited discrete separation among rohu, catla, and their hybrids when the data points were plotted in a low-dimensional 2-D plane using the first 2 principal components. Out of 40 selected single nucleotide polymorphism (SNP) positions of the COX1 gene, hybrid showed 100% similarity with catla. Concerning SNP similarity of the 18S rRNA nuclear gene, the hybrid showed 100% similarity with rohu but not with catla; exhibiting its probable parental inheritance., Conclusions: Along with morphometric analysis, the SNP comparison study together points towards strong evidence of interspecific hybridization between rohu and catla, as these hybrids share both morphological and molecular differences with either parent. However, this study will help screen the hybrids from their wild parents, as a strategy for conservational management., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The Chungtien schizothoracin (Ptychobarbus chungtienensis), an endangered fish species endemic to the Zhongdian Plateau, remains underexplored in terms of transcriptomic sequencing. This investigation used tissues from five distinct organs (heart, liver, spleen, kidney, and brain) of the Chungtien schizothoracin for PacBio Iso-seq and RNA-seq analyses, yielding a repertoire of 16,598 full-length transcripts spanning lengths from 363 bp to 7,157 bp. Gene family clustering and phylogenetic analysis encompassed a comprehensive set of 13 fish species, all of which were cyprinids, including the zebrafish and the examined species Ptychobarbus chungtienensis. Moreover, the identification of long non-coding RNAs (lncRNAs) and coding sequences was accomplished across all five tissues. Comprehensive analyses of gene expression profiles and differentially expressed genes among the above five tissues were performed. In summary, the obtained full-length transcripts and detailed gene expression profiles of the Chungtien schizothoracin tissues furnish crucial expression data and genetic sequences, laying the groundwork for future investigations and fostering a holistic comprehension of the adaptive mechanisms inherent in the Chungtien schizothoracin under various conditions., (© 2024. The Author(s).)

The lake minnow Eupallasella percnurus is a small leuciscid fish. In Poland, this species has been in a continuous decline since the mid-20th century and is presently considered as a extremely endangered. According to Polish law, E. percnurus is a strictly protected species that requires active conservation measures. In Poland, one the most common and effective measure of active protection E. percnurus is initiation of new populations. For this purpose, in 2004-2012, juvenile individuals originating from aquaculture conditions were translocated to group of isolated water bodies not inhabited by this species. The juveniles were offspring of parental fish belonging to the same local population, which is extinct at present. Five of those attempts were successful. The aim of the present study was to assess the genetic variation in a group new populations and compare genetic variation indicators with 13 old populations that had existed for decades. The polymorphism of 13 microsatellite markers was investigated, significance of differences in the genetic variation indicators between the groups were tested using a one-way analysis of variance (ANOVA). The mean values of all summary statistics under study, i.e. observed heterozygosity, expected heterozygosity and the total number of alleles, were higher in the group of new populations compared to almost all old ones. A similar dependence was found for Garza-Williamson M values, where the mean for the group of new populations was higher than in almost all old populations. Our results indicate that all recently established E. percnurus populations have not yet experienced any extensive founder effects or bottlenecks. They have preserved a large part of the genetic variability typical of their maternal population, which might also have been relatively high. This feature of new populations, may give them a relatively high ability to adapt to changing environments in the future., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Wolnicki et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Quantitative real-time PCR (qRT-PCR) has been widely employed for the study of gene expression in fish, and accurate normalization is crucial. In this study, we aimed to identify the most stably expressed genes in various tissues, different developmental stages, and within astaxanthin treatment groups in Lutjanus erythropterus. Twelve candidate genes (EEF1A, CYB5R3, DLD, IDH3A, MRPL17, MRPL43, NDUFS7, PABPC1, PAGR1, PFDN2, PSMC3, and RAB10) were examined via qRT-PCR. We employed geNorm and NormFinder to assess their stability. The results revealed that RAB10 and PFDN2 exhibited relatively stable expression patterns across different tissue and astaxanthin treatment groups, while NDUFS7 and MRPL17 proved to be the most reliable reference gene combinations across various developmental stages. The stability of these selected genes was further validated by assessing the expression of two target genes, CRADD and CAPNS1, across developmental stages, reinforcing the reliability of NDUFS7 as it closely aligned with transcriptome-wide expression patterns at these stages. The present results will help researchers to obtain more accurate results in future qRT-PCR analysis in L. erythropterus., (© 2024. The Author(s).)

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout ( Onchorhynchus mykiss ), Atlantic salmon ( Salmo salar ), common carp ( Cyprinus carpio ), goldfish ( Carassius auratus ), Gibel carp ( Carassius gibelio ) and the model fish zebrafish ( Danio rerio ). Among the genes studied, the most applicable for aquaculture are mstnba , pomc , and acvr2 , the knockout of which leads to enhanced muscle growth; runx2b , mutants of which do not form bones in myoseptae; lepr , whose lack of function makes fish fast-growing; fads2 , Δ6abc/5Mt , and Δ6bcMt , affecting the composition of fatty acids in fish meat; dnd mettl3 , and wnt4a , mutants of which are sterile; and disease-susceptibility genes prmt7 , gab3 , gcJAM-A , and cxcr3.2 . Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use.

Fish typically adapt to their environment through evolutionary traits, and this adaptive strategy plays a critical role in promoting species diversity. Onychostoma macrolepis is a rare and endangered wild species that exhibits a life history of overwintering in caves and breeding in mountain streams. We analyzed the morphological characteristics, histological structure, and expression of circadian clock genes in O. macrolepis to elucidate its adaptive strategies to environmental changes in this study. The results showed that the relative values of O. macrolepis eye diameter, body height, and caudal peduncle height enlarged significantly during the breeding period. The outer layer of the heart was dense; the ventricular myocardial wall was thickened; the fat was accumulated in the liver cells; the red and white pulp structures of the spleen, renal tubules, and glomeruli were increased; and the goblet cells of the intestine were decreased in the breeding period. In addition, the spermatogenic cyst contained mature sperm, and the ovaries were filled with eggs at various stages of development. Throughout the overwintering period, the melano-macrophage center is located between the spleen and kidney, and the melano-macrophage center in the cytoplasm has the ability to synthesize melanin, and is arranged in clusters to form cell clusters or white pulp scattered in it. Circadian clock genes were identified in all organs, exhibiting significant differences between the before/after overwintering period and the breeding period. These findings indicate that the environment plays an important role in shaping the behavior of O. macrolepis, helping the animals to build self-defense mechanisms during cyclical habitat changes. Studying the morphological, histological structure and circadian clock gene expression of O. macrolepis during the overwintering and breeding periods is beneficial for understanding its unique hibernation behavior in caves. Additionally, it provides an excellent biological sample for investigating the environmental adaptability of atypical cavefish species., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Water temperature is a crucial environmental factor that significantly affects the physiological and biochemical processes of fish. Due to the occurrence of cold events in aquaculture, it is imperative to investigate how fish respond to cold stress. This study aims to uncover the mechanisms responds to acute cold stress by conducting a comprehensive analysis of the histomorphology, glycolipid metabolic and antioxidant enzymes, fatty acid composition and transcriptome at three temperatures (16 °C, 10 °C and 4 °C) in Phoxinus lagowskii. Our results showed that cold stress not damaged muscle microstructure but caused autophagy (at 10 °C). In addition, serum glucose (Glu) and triglycerides (TG) increased during cold stress. The activities of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), fructose phosphokinase (PFK), hexokinase (HK), pyruvate kinase (PK), and malondialdehyde (MDA) content in muscle were measured and analyzed. During cold stress, superoxide dismutase and catalase activities increased, reactive oxygen species content decreased. No significant difference in Glutathione peroxidase (GPx) activity, malondialdehyde and total cholesterol (T-CHO) contents among groups. Phosphokinase and pyruvate kinase activities decreased, and HK activity increased during cold stress. Our study resulted in the identification of a total of 25,400 genes, with 2524 genes showing differential expression across different temperature treatments. Furthermore, KEGG pathway indicated that some pathways upregulated during light cold stress (at 10 °C, including autophagy, and AMP-activated protein kinase (AMPK) signaling pathway. Additionally, circadian rhythm is among the most enriched pathways in genes up-regulated during severe cold stress (at 4 °C). Our findings offer valuable insights into how cold-water fish respond to cold stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris-Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni-microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal-fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3-4 unbranched and 9½-10½ dorsal-fin branched rays, 12-14 pectoral-fin rays, 7-8 pelvic-fin rays, 2-3 unbranched and 6½-7½ branched anal-fin rays, and 37-40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura-2-Parameter model distance of 5.3%., (© 2024 Fisheries Society of the British Isles.)

Background: Environmental temperature is critical in regulating biological functions in fish. S. prenanti is a kind of cold-water fish, but of which we have little knowledge about the metabolic adaptation and physiological responses to long-term cold acclimation., Results: In this study, we determined the physiological responses of S. prenanti serum after 30 days of exposure to 6℃. Compared with the control group, the levels of TC, TG, and LDL-C in the serum were significantly (P < 0.05) increased, and the level of glucose was significantly (P < 0.05) decreased under cold acclimation. Cold acclimation had no effect on the gene expression of pro-inflammatory factors and anti-inflammatory factors of S. prenanti. Metabolomics analysis by LC-MS showed that a total of 60 differential expressed metabolites were identified after cold acclimation, which involved in biosynthesis of amino acids, biosynthesis of unsaturated fatty acids, steroid degradation, purine metabolism, and citrate cycle pathways., Conclusion: The results indicate that cold acclimation can alter serum metabolites and metabolic pathways to alter energy metabolism and provide insights for the physiological regulation of cold-water fish in response to cold acclimation., (© 2024. The Author(s).)

Leuciscus merzbacheri is a native fish species found exclusively in the Junggar Basin in Xinjiang. It exhibits remarkable adaptability, thriving in varying water conditions such as the saline waters, the semi-saline water, and the freshwater. Despite its significant economic and ecological value, the underlying mechanisms of its remarkable salinity tolerance remain elusive. Our study marks the first time the full-length transcriptome of L. merzbacheri has been reported, utilizing RNA-Seq and PacBio Iso-Seq technologies. We found that the average length of the full-length transcriptome is 1,780 bp, with an N50 length of 2,358 bp. We collected RNA-Seq data from gill, liver, and kidney tissues of L. merzbacheri from both saline water and freshwater environments and conducted comparative analyses across these tissues. Further analysis revealed significant enrichment in several key functional gene categories and signalling pathways related to stress response and environmental adaptation. The findings provide a valuable genetic resource for further investigation into saline-responsive candidate genes, which will deepen our understanding of teleost adaptation to extreme environmental stress. This knowledge is crucial for the future breeding and conservation of native fish species., (© The Author(s) 2024. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.)

Background: Mitochondrial DNA (mtDNA) has become a significant tool for exploring genetic diversity and delineating evolutionary links across diverse taxa. Within the group of cold-water fish species that are native to the Indian Himalayan region, Schizothorax esocinus holds particular importance due to its ecological significance and is potentially vulnerable to environmental changes. This research aims to clarify the phylogenetic relationships within the Schizothorax genus by utilizing mitochondrial protein-coding genes., Methods: Standard protocols were followed for the isolation of DNA from S. esocinus. For the amplification of mtDNA, overlapping primers were used, and then subsequent sequencing was performed. The genetic features were investigated by the application of bioinformatic approaches. These approaches covered the evaluation of nucleotide composition, codon usage, selective pressure using nonsynonymous substitution /synonymous substitution (Ka/Ks) ratios, and phylogenetic analysis., Results: The study specifically examined the 13 protein-coding genes of Schizothorax species which belongs to the Schizothoracinae subfamily. Nucleotide composition analysis showed a bias towards A + T content, consistent with other cyprinid fish species, suggesting evolutionary conservation. Relative Synonymous Codon Usage highlighted leucine as the most frequent (5.18%) and cysteine as the least frequent (0.78%) codon. The positive AT-skew and the predominantly negative GC-skew indicated the abundance of A and C. Comparative analysis revealed significant conservation of amino acids in multiple genes. The majority of amino acids were hydrophobic rather than polar. The purifying selection was revealed by the genetic distance and Ka/Ks ratios. Phylogenetic study revealed a significant genetic divergence between S. esocinus and other Schizothorax species with interspecific K2P distances ranging from 0.00 to 8.87%, with an average of 5.76%., Conclusion: The present study provides significant contributions to the understanding of mitochondrial genome diversity and genetic evolution mechanisms in Schizothoracinae, hence offering vital insights for the development of conservation initiatives aimed at protecting freshwater fish species., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Pseudomonas species are one of the most threatening fish pathogens which reside a wide range of environments. In this study, the dominant bacteria were isolated from diseased Malaysian mahseer (Tor tambroides) and tentatively named CM-01. It was identified as Pseudomonas koreensis based on its biochemical, morphological, genetic and physiological information. Its pathogenicity was found to be correlated with twelve virulence genes identified including iron uptake, protease, acylhomoserine lactone synthase gacS/gacA component regulation system, type IV secretion system, hydrogen cyanide production, exolysin, alginate biosynthesis, flagella and pili. The median lethal dose (LD50) for the CM-01 isolate on Malaysian mahseer was documented at 5.01 × 10 7  CFU/mL. The experimental infection revealed that CM-01 led to significant histological lesions in the fish, ultimately resulting in death. These lesions comprise necrosis, tissue thickening and aggregation. Drug sensitivity tests had shown its susceptibility to beta-lactam combination agents and further suggest its drug of choice. Its growing features had shown its growth at optimal temperature and pH. To the best of our knowledge, this is the first report of P. koreensis linked to diseased T. tambroides. STATEMENT OF RELEVANCE: In this research, a novel strain of Pseudomonas koreensis, CM-01 was isolated from diseased T. tambroides for the first time. The antimicrobial susceptibility, pathogenicity, virulence genes and growth characteristics of CM-01 were studied. These findings established a scientific foundation for the recognition of P. koreensis and the management of fish infections caused by this pathogen., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, the toxicogenomic effects of five cytostatics (tamoxifen, methotrexate, capecitabine, cyclophosphamide, and ifosfamide) on fathead minnow (Pimephales promelas) larvae were evaluated. Post-fertilization eggs were exposed to increasing concentrations of the drugs for six days. The expression levels of two genetic biomarkers for toxicity and four thyroid hormone-related gene pathways were measured. Interestingly, the results showed that all concentrations of the five cytostatics affect the transcription levels of both toxicity biomarker genes. Additionally, the thyroid hormone-related genes had different expression levels than the control, with the most significant changes observed in those larvae exposed to cyclophosphamide and ifosfamide. While a previous study found no effects on fish morphology, this study suggests that the five cytostatics modify subtle molecular responses of P. promelas, highlighting the importance of assessing multibiological level endpoints throughout the lifecycle of animals to understand the full portrait of potential effects of cytostatics and other contaminants., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Both silent information regulator 2 homolog 1 (sirt1) and forkhead box transcription factor 1 (foxO1) are crucial transcription factors involved in glucolipid metabolism and energy regulation. The presnt study aimed to understand their regulatory roles in glucose metabolism. Molecular cloning and sequencing of sirt1 gene of Megalobrama amblycephala (masirt1) was conducted and cellular localization of both the factors were analysed. Their effects and action patterns in the glucose metabolism of Megalobrama amblycephala (M. amblycephala) were investigated through acute and long-term glucose tolerance assays. The results revealed that the full-length masirt1 cDNA sequence was 2350 bp and closely related to Sinocyclocheilus rhinocerous. Sirt1 and foxO1 were found to be mutually dependent and localized in the nucleus. Acute glucose tolerance tests revealed that the expression levels of both factors in the liver of M. amblycephala showed an initial increase followed by a decrease. Plasma glucose levels in M. amblycephala significantly increased at 2 and 12 h (P < 0.05). In a long-term breeding experiment with high-sugar feeding, the expressions of the sirt1 and foxO1 genes in the kidney and intestine of M. amblycephala exhibited synergistic changes. The 51WS groups had significantly higher levels of sirt1 and foxO1 gene expression in the kidney and intestine compared to the 0WS and 17WS groups (P < 0.05). Overall, masirt1 is evolutionarily highly conserved, and the interaction site of sirt1 and foxO1 is located in the nucleus. In long-term hyperglycemic regulation, sirt1 and foxO1 exhibit synergistic regulatory effects in the kidney and intestine of M. amblycephala. This study provides insights into how sirt1 and foxO1 regulate glucose metabolism in M. amblycephala., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)