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Abstract Endemic to the upper and middle reaches of the Yangtze River in China, elongate loach (Leptobotia elongata) has become a vulnerable species mainly due to overfishing and habitat destruction. Thus far, no genome data of this species are reported. As a result, lacking of such genomic information has restricted practical conservation and utilization of this economic fish. Here, we constructed chromosome-level genome assemblies for both male and female elongate loach by integration of MGI, PacBio HiFi and Hi-C sequencing technologies. Two primary genome assemblies (586-Mb and 589-Mb) were obtained for female and male fishes, respectively. Indeed, 98.22% and 98.61% of the contig sequences were anchored onto 25 chromosomes, with identification of 26.22% and 25.92% repeat contents in both assembled genomes. Meanwhile, a total of 25,215 and 25,253 protein-coding genes were annotated, of which 97.41% and 98.8% could be predicted with functions. Taken together, our genome data presented here provide a valuable genomic resource for in-depth evolutionary and functional research, as well as molecular breeding and conservation of this economic fish species.

Introduction: Mudskippers are a large group of amphibious fishes that have developed many morphological and physiological capacities to live on land. Genomics comparisons of chromosome-level genome assemblies of three representative mudskippers, Boleophthalmus pectinirostris (BP), Periophthalmus magnuspinnatus (PM) and P. modestus (PMO), may be able to provide novel insights into the water-to-land evolution and adaptation. Methods: Two chromosome-level genome assemblies for BP and PM were respectively sequenced by an integration of PacBio, Nanopore and Hi-C sequencing. A series of standard assembly and annotation pipelines were subsequently performed for both mudskippers. We also re-annotated the PMO genome, downloaded from NCBI, to obtain a redundancy-reduced annotation. Three-way comparative analyses of the three mudskipper genomes in a large scale were carried out to discover detailed genomic differences, such as different gene sizes, and potential chromosomal fission and fusion events. Comparisons of several representative gene families among the three amphibious mudskippers and some other teleosts were also performed to find some molecular clues for terrestrial adaptation. Results: We obtained two high-quality haplotype genome assemblies with 23 and 25 chromosomes for BP and PM respectively. We also found two specific chromosome fission events in PM. Ancestor chromosome analysis has discovered a common fusion event in mudskipper ancestor. This fusion was then retained in all the three mudskipper species. A loss of some SCPP (secretory calcium-binding phosphoprotein) genes were identified in the three mudskipper genomes, which could lead to reduction of scales for a part-time terrestrial residence. The loss of aanat1a gene, encoding an important enzyme (arylalkylamine N-acetyltransferase 1a, AANAT1a) for dopamine metabolism and melatonin biosynthesis, was confirmed in PM but not in PMO (as previously reported existence in BP), suggesting a better air vision of PM than both PMO and BP. Such a tiny variation within the genus Periophthalmus exemplifies to prove a step-by-step evolution for the mudskippers’ water-to-land adaptation. Conclusion: These high-quality mudskipper genome assemblies will become valuable genetic resources for in-depth discovery of genomic evolution for the terrestrial adaptation of amphibious fishes.

Aquaculture, as a rapidly growing industry, plays a significant role in global food production and economic development. However, various infectious diseases, particularly those caused by the gram-negative bacterium Aeromonas hydrophila, pose a critical threat to the sustainability and productivity of world-wide aquaculture operations. Investigating the molecular mechanisms of A. hydrophila infection can help to identify key targets for therapeutic interventions and vaccines, thereby reducing economic losses associated with disease outbreaks. Our present study focuses on wide-bodied sand loach (WBSL, Sinibotia reevesae), a captive-bred commercial fish, to explore detailed molecular effects of exogenous A. hydrophila infection. Firstly, a high-quality chromosome-level haplotype genome with a total length of 774 Mb and 49 chromosomes was assembled, providing valuable insights into its genetic components. Secondly, we isolated and characterized a newfound A. hydrophila F4S strain, examined pathological symptoms of WBSL after infection, and then investigated dynamic gene expressions. Our results revealed that the bacterial infection decreased metabolic activity, causing disruptions in cardiac function, cellular homeostasis, tissue damages, and impaired energy utilization. The immune system responds multifaceted, potentially impacting overall health and survival. In summary, our findings contribute to the understanding of the complicated interactions between WBSL and exogenous A. hydrophila, especially shed lights on the genetic complexity, immune responses, and potential impacts on fish health and survival. Furthermore, this study provides new insights into the mechanisms underlying A. hydrophila infection, and offers potential strategies to offload corresponding pathological effects, not only in WBSL but also in other aquaculture species.

ObjectiveHigh-grade serous ovarian cancer (HGSOC) has the highest mortality rate among female reproductive system tumors. Accurate preoperative assessment is crucial for treatment planning. This study aims to develop multitask prediction models for HGSOC using radiomics analysis based on preoperative CT images.MethodsThis study enrolled 112 patients diagnosed with HGSOC. Laboratory findings, including serum levels of CA125, HE-4, and NLR, were collected. Radiomic features were extracted from manually delineated ROI on CT images by two radiologists. Classification models were developed using selected optimal feature sets to predict R0 resection, lymph node invasion, and distant metastasis status. Model evaluation was conducted by quantifying receiver operating curves (ROC), calculating the area under the curve (AUC), De Long’s test.ResultsThe radiomics models applied to CT images demonstrated superior performance in the testing set compared to the clinical models. The area under the curve (AUC) values for the combined model in predicting R0 resection were 0.913 and 0.881 in the training and testing datasets, respectively. De Long’s test indicated significant differences between the combined and clinical models in the testing set (p = 0.003). For predicting lymph node invasion, the AUCs of the combined model were 0.868 and 0.800 in the training and testing datasets, respectively. The results also revealed significant differences between the combined and clinical models in the testing set (p = 0.002). The combined model for predicting distant metastasis achieved AUCs of 0.872 and 0.796 in the training and test datasets, respectively. The combined model displayed excellent agreement between observed and predicted results in predicting R0 resection, while the radiomics model demonstrated better calibration than both the clinical model and combined model in predicting lymph node invasion and distant metastasis. The decision curve analysis (DCA) for predicting R0 resection favored the combined model over both the clinical and radiomics models, whereas for predicting lymph node invasion and distant metastasis, DCA favored the radiomics model over both the clinical model and combined model.ConclusionThe identified radiomics signature holds potential value in preoperatively evaluating the R0, lymph node invasion and distant metastasis in patients with HGSC. The radiomics nomogram demonstrated the incremental value of clinical predictors for surgical outcome and metastasis estimation.

Summary: Amphibians, like the paddy frog (Fejervarya multistriata), have played a critical role in the transition from water to land. Hibernation is a vital survival adaptation in cold environments with limited food resources. We decoded the paddy frog genome to reveal the molecular adaptations linked to hibernation in ectotherms. The genome contained 13 chromosomes, with a significant proportion of repetitive sequences. We identified the key genes encoding the proteins of AANAT, TRPM8, EGLN1, and VEGFA essential for circadian rhythms, thermosensation, and hypoxia during hibernation by comparing the hibernator and non-hibernator genomes. Examining organ changes during hibernation revealed the central regulatory role of the brain. We identified 21 factors contributing to hibernation, involving hormone biosynthesis, protein digestion, DNA replication, and the cell cycle. These findings provide deeper insight into the complex mechanisms of ectothermic hibernation and contribute to our understanding of the broader significance of this evolutionary adaptation.

Animals have evolved sophisticated temperature-sensing systems and mechanisms to detect and respond to ambient temperature changes. As a relict species endemic to the Qinghai-Tibet Plateau, hot-spring snake (Thermophis baileyi) survived the dramatic changes in climate that occurred during plateau uplift and ice ages, providing an excellent opportunity to explore the evolution of temperature sensation in ectotherms. Based on distributional information and behavioral experiments, we found that T. baileyi prefer hot-spring habitats and respond more quickly to warmth than other two snakes, suggesting that T. baileyi may evolve an efficient thermal-sensing system. Using high-quality chromosome-level assembly and comparative genomic analysis, we identified cold acclimation genes experiencing convergent acceleration in high-altitude lineages. We also discovered significant evolutionary changes in thermosensation- and thermoregulation-related genes, including the transient receptor potential (TRP) channels. Among these genes, TRPA1 exhibited three species-specific amino acid replacements, which differed from those found in infrared imaging snakes, implying different temperature-sensing molecular strategies. Based on laser-heating experiments, the T. baileyi-specific mutations in TRPA1 resulted in an increase in heat-induced opening probability and thermal sensitivity of the ion channels under the same degree of temperature stimulation, which may help the organism respond to temperature changes more quickly. These results provide insight into the genetic mechanisms underpinning the evolution of temperature-sensing strategies in ectotherms as well as genetic evidence of temperature acclimation in this group.

Comprising a major clade of Anura, toads produce and secrete numerous toxins from both the parotoid glands behind their eyes and their dorsal skin. These toxins, made of various proteins and compounds, possess pharmacological potential to be repurposed to benefit human health. However, the detailed genetic regulation of toad toxin production is still poorly understood. A recent publication uncovering the genome of the representative Asiatic toad (Bufo gargarizans) provides a good reference to resolve this issue. In the present study, we sequenced the transcriptomes of parotoid gland, dorsal skin and liver from the Asiatic toad. Combining our data with 35 previously published transcriptomes across eight different tissues from the same species but from different locations, we constructed a comprehensive gene co-expression network of the Asiatic toad with the assistance of the reference genome assembly. We identified 2,701 co-expressed genes in the toxin-producing tissues (including parotoid gland and dorsal skin). By comparative genomic analysis, we identified 599 expanded gene families with 2,720 genes. Through overlapping these co-expressed genes in the toad toxin-producing tissues, we observed that three cytochrome P450 (Cyp) family members (Cyp27a1, Cyp2c29, and Cyp2c39) were significantly enriched in pathways related to cholesterol metabolism. Cholesterol is a critical precursor to steroids, and the known main steroidal toxins of bufadienolides are considered as the major bioactive components in the parotoid glands of Asiatic toad. We found 3-hydroxy-methylglutaryl CoA reductase (hmgcr), encoding the major rate-limiting enzyme for cholesterol biosynthesis, appears with multiple copies in both Asiatic toad and common toad, possibly originating from a tandem duplication event. The five copies of hmgcr genes consistently displayed higher transcription levels in the parotoid gland when compared with the abdominal skin, suggesting it as a vital candidate gene in the involvement of toad toxin production. Taken together, our current study uncovers transcriptomic and gene-family dynamic evidence to reveal the vital role of both expanded gene copies and gene expression changes for production of toad toxins.

Midas cichlid (Amphilophus citrinellus), a popular aquarium fish, attracts extensive attention from worldwide biologists mainly due to its morphological polymorphism (dark versus gold). Continuous efforts have therefore been paid to address mechanisms of its coloration variants, while it is far away from the detailed illustration of a clear regulatory network. Some limits may come from the absence of a high-quality genome assembly and a relatively accurate gene set. In this study, we sequenced about 149 Gb of nucleotide sequences of Midas cichlid, generating a genome assembly with a total size of 933.5 Mb, which exhibits a good genome continuity with a contig N50 of 10.5 Mb. A total of 25,911 protein-coding genes were annotated and about 90% completeness was achieved, which helps to build a good gene pool for understanding expressional differences of color variation. With the assistance of the final gene set, we identified a total of 277 differential expressional genes (DEGs), of which 97 up- and 180 downregulated were determined in dark-vs-gold comparisons. Two protein-protein interaction (PPI) networks were constructed from these DEGs, and three key functional modules were classified. Hub genes within each module were evaluated, and we found that the third key module contains tyrp1b, oca2, pmela, tyr, and slc24a5, which were previously proven to be associated with melanin formation. Two downregulated DEGs (myl1 and pgam2) in the first key module may be involved in muscle movement and spermatogenesis, implying that certain side effects could result from the morphological polymorphism. The first key module, consisting of proteins encoded by upregulated DEGs that were associated with MAPK signaling, Toll-like receptor signaling, and gonadotropin-releasing hormone pathways, may contribute to a negative upstream regulation or downstream influence on melanin biosynthesis. Taken together, our new genome assembly and gene annotation of Midas cichlid provide a high-quality genetic resource for biological studies on this species, and the newly identified key networks and hub genes in dark-vs-gold comparisons enhance our understanding of the transcriptional regulatory mechanisms underlying coloration changes not only in Midas cichlid but also in other fishes from freshwater to marine ecosystems.

As an important economic and medicinal crop, Amomum tsao-ko is rich in volatile oils and widely used in food additives, essential oils, and traditional Chinese medicine. However, the lack of the genome remains a limiting factor for understanding its medicinal properties at the molecular level. Here, based on 288.72 Gb of PacBio long reads and 105.45 Gb of Illumina paired-end short reads, we assembled a draft genome for A. tsao-ko (2.70 Gb in size, contig N50 of 2.45 Mb). Approximately 90.07% of the predicted genes were annotated in public databases. Based on comparative genomic analysis, genes involved in secondary metabolite biosynthesis, flavonoid metabolism, and terpenoid biosynthesis showed significant expansion. Notably, the DXS, GGPPS, and CYP450 genes, which participate in rate-limiting steps for terpenoid backbone biosynthesis and modification, may form the genetic basis for essential oil formation in A. tsao-ko. The assembled A. tsao-ko draft genome provides a valuable genetic resource for understanding the unique features of this plant and for further evolutionary and agronomic studies of Zingiberaceae species.

Anan’s rock agama (Laudakia sacra) is a lizard species endemic to the harsh high-altitude environment of the Qinghai–Tibet Plateau, a region characterized by low oxygen tension and high ultraviolet (UV) radiation. To better understand the genetic mechanisms underlying highland adaptation of ectotherms, we assembled a 1.80-Gb L. sacra genome, which contained 284 contigs with an N50 of 20.19 Mb and a BUSCO score of 93.54%. Comparative genomic analysis indicated that mutations in certain genes, including HIF1A, TIE2, and NFAT family members and genes in the respiratory chain, may be common adaptations to hypoxia among high-altitude animals. Compared with lowland reptiles, MLIP showed a convergent mutation in L. sacra and the Tibetan hot-spring snake (Thermophis baileyi), which may affect their hypoxia adaptation. In L. sacra, several genes related to cardiovascular remodeling, erythropoiesis, oxidative phosphorylation, and DNA repair may also be tailored for adaptation to UV radiation and hypoxia. Of note, ERCC6 and MSH2, two genes associated with adaptation to UV radiation in T. baileyi, exhibited L. sacra-specific mutations that may affect peptide function. Thus, this study provides new insights into the potential mechanisms underpinning high-altitude adaptation in ectotherms and reveals certain genetic generalities for animals’ survival on the plateau.

The Sinocyclocheilus cyphotergous, belonging to the family Cyprinidae, is endemic to the Karst area of the Yunnan-Guizhou Plateau. Here, we determined the complete mitogenome of S. cyphotergous using an Illumina Hiseq X Ten sequencer. This mitogenome's structure is typical circular with 16,611 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region. The overall base composition of S. cyphotergous is 31.33% A, 25.89% T, 26.49% C, and 16.29% G with a slight AT bias of 57.22%. Most mitochondrial genes except ND6 and eight tRNAs were encoded on the heavy strand. All tRNA genes fold into the typical cloverleaf secondary structures, except for tRNA-Ser (AGY) that lacked the dihydrouracil arm. 15 of 22 tRNA genes were found to have 29 G-U mismatches in their secondary structures, which formed a weak bond. In addition, mismatches of A-C, C-C, U-U, and A-A were also found in their tRNA secondary structures. Result of substitution rate estimation among the mitochondrial protein coding genes (PCGs) showed ATP8 had the largest average Ka and Ka/Ks, while COI had the lowest, which implied that ATP8 might evolve more quickly than the other mitochondrial protein coding genes. Phylogenetic analyses based on Bayesian inference (BI) and maximum likelihood (ML) revealed all Sinocyclocheilus species in this research formed a solid monophyletic group and grouped into two major clades with strong support excluded S. jii. Additionally, S. cyphotergous in this study was closely related to S. multipunctatus and S. punctatus. In summary, this study provided novel insights into the phylogeny of the Sinocyclocheilus fishes, conducive to the conservation genetics and cave adaptation for S. cyphotergous. [ABSTRACT FROM AUTHOR]

Sinibotia superciliaris and S. reevesae are two economically important loaches in the middle and upper reaches of Yangtze River. Recently, wild populations of them have dropped sharply due to anthropogenic and environmental threats. There is an increasing need to implement captive propagation programs to protect their populations. Here, we firstly carried out artificial breeding of S. superciliaris and S. reevesae, and hybrid combinations were designed as S. superciliaris ♀ × S. reevesae ♂, and S. superciliaris ♂ × S. reevesae ♀. Secondly, 19 microsatellite loci were used to evaluate genetic diversity between hybrid offspring and their parents. The mean polymorphic information content (PIC) among groups ranged from 0.685 to 0.818, implying high polymorphism in all of the four groups (PIC > 0.5). The mean observed heterozygosity ranged from 0.779 to 0.887, and the hybrid combination of S. superciliaris ♀ × S. reevesae ♂ obtained the highest observed heterozygosity, while S. reevesae had the lowest. The high heterozygosity was helpful for protecting the genetic resources and preventing the genetic decline, which could reduce the risk of inbreeding due to loss of heterozygosity. Thus, we recommend the hybrid strategy of S. superciliaris ♀ × S. reevesae ♂ as the potential germplasm resources for further artificial reproduction. Population structure analysis and UPGMA tree indicated S. superciliaris and S. superciliaris ♀ × S. reevesae ♂ were clustered together that comprised of clade I, and S. reevesae and S. superciliaris ♂ × S. reevesae ♀ were clustered together that comprised of clade II, suggesting the close genetic relationship between the offspring and their female parents. This study provides reasonable comparison of genetic diversity and potential application of hybrid strategy of S. superciliaris and S. reevesae, and the population genetic information supplied here will provide valuable resources for breeding, germplasm resources preservation and conservation genetics of these two loaches. [ABSTRACT FROM AUTHOR]