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Ovarian development in animals is a complicated biological process, requiring the simultaneous coordination among various genes and pathways. To understand the dynamic changes and molecular regulatory mechanisms of ovarian development in mud crab (Scylla paramamosain), both histological observation and whole transcriptome sequencing of ovarian tissues at different mating stages were implemented in this study. The histological results revealed that ovarian development was delayed in unmated females (60 days after courtship behavior but not mating), who exhibited an oocyte diameter of 56.38 ± 15.17 μm. Conversely, mated females exhibited accelerated the ovarian maturation process, with females reaching ovarian stage III (proliferative stage) 23 days after mating and attained an average oocyte diameter of 132.19 ± 15.07 μm. Thus, mating process is essential in promoting the rapid ovarian development in mud crab. Based on the whole transcriptome sequencing analysis, a total of 518 mRNAs, 1502 lncRNAs, 18 circRNAs and 151 miRNAs were identified to be differentially expressed between ovarian tissues at different mating stages. Notably, six differentially expressed genes (DEGs) associated with ovarian development were identified, including ovary development-related protein , red pigment concentrating hormone receptor , G2/mitotic-specific cyclin-B3-like , lutropin-chorio gonadotropic hormone receptor , renin receptor , and SoxB2. More importantly, both DEGs and targets of differentially expressed non-coding RNAs (DEncRNAs) were enriched in renin-angiotensin system, TGF-β signaling, cell adhesion molecules, MAPK signaling pathway, and ECM-receptor interaction, suggesting that these pathways may play significant roles in the ovarian development of mud crabs. Moreover, competition endogenous RNA (ceRNA) networks were constructed while mRNAs were differentially expressed between mating stages were involved in Gene Ontology (GO) biological processes such as developmental process, reproduction, and growth. These findings could provide solid foundations for the future development of female mud crab maturation enhancement strategy, and improve the understanding of the ovarian maturation process in crustaceans. [Display omitted] • Mating process promotes rapid ovarian development in S. paramamosain. • Six genes are identified to be connected with ovarian development. • Pathways related to cell proliferation, differentiation, and migration are highlighted. • Competition endogenous RNA networks at different mating stages are constructed. [ABSTRACT FROM AUTHOR]

The mud crab (Scylla paramamosain) possesses extensive regenerative abilities, enabling it to replace missing body parts, including claws, legs, and even eyes. Studying the genetic and molecular mechanisms underlying regenerative ability in diverse animal phyla has the potential to provide new insights into regenerative medicine in humans. In the present study, we performed mRNA sequencing to reveal the genetic mechanisms underlying the claw regeneration in mud crab. Several differentially expressed genes (DEGs) were expressed in biological pathways associated with cuticle synthase, collagen synthase, tissue regeneration, blastema formation, wound healing, cell cycle, cell division, and cell migration. The top GO enrichment terms were microtubule-based process, collagen trimer, cell cycle process, and extracellular matrix structural constituent. The most enriched KEGG pathways were ECM-receptor interaction and focal adhesion. The genes encoding key functional proteins, such as collagen alpha, cuticle protein, early cuticle protein, arthrodial cuticle protein, dentin sialophosphoprotein (DSPP), epidermal growth factor receptor (EGFR), kinesin family member C1 (KIFC1), and DNA replication licensing factor mcm2-like (MCM2) were the most significant and important DEGs suspected to participate in claw regeneration. The findings of this research offer a comprehensive and insightful understanding of the genetic and molecular mechanisms underlying claw regeneration in S. paramamosain. By elucidating the specific genes and molecular pathways implicated in this process, our study contributes significantly to the broader field of regenerative biology and offers potential avenues for further exploration in crustacean limb regeneration. [Display omitted] • Several DEGs and biological pathways were identified. • Chitin and collagen-related genes plays important role in the claw regeneration. • Key genes were collagen alpha, DSPP, FRAS1, cuticle protein, EGFR, HAUS5, and KIFC1. • Top GO terms were extracellular matrix, microtubule-based, and collagen trimer. • The most enriched KEGG pathways were ECM-receptor interaction and focal adhesion. [ABSTRACT FROM AUTHOR]

In the present study, BGISEQ-500 RNA-Seq technology was adopted to investigate how Scylla paramamosain adapts to salinity tolerance at the molecular level and explores changes in gene expression linked to salinity adaptation following exposure to both low salinity (5 ‰) and standard salinity (23 ‰) conditions. A total of 1100 and 520 differentially expressed genes (DEGs) were identified in the anterior and posterior gills, respectively, and their corresponding expression patterns were visualized in volcano plots and a heatmap. Further analysis highlighted significant enrichment of well-established gene functional categories and signaling pathways, including those what associated with cellular stress response, ion transport, energy metabolism, amino acid metabolism, H 2 O transport, and physiological stress compensation. We also selected key DEGs within the anterior and posterior gills that encode pivotal stress adaptation and tolerance modulators, including AQP, ABCA1, HSP 10, A35, CAg, NKA, VPA, CAc, and SPS. Interestingly, A35 in the gills might regulate osmolality by binding CHH in response to low salinity stress or serve as a mechanism for energy compensation. Taken together, our findings elucidated the intricate molecular mechanism employed by S. paramamosain for salinity adaptation, which involved distinct gene expression patterns in the anterior and posterior gills. These findings provide the foothold for subsequent investigations into salinity-responsive candidate genes and contribute to a deeper understanding of S. paramamosain 's adaptation mechanisms in low-salinity surroundings, which is crucial for the development of low-salinity species cultivation and the establishment of a robust culture model. [Display omitted] • Compared the transcriptomes of the anterior and posterior gills of the mud crab. • Nine DEGs were selected and their expression was validated by RT-qPCR. • The 5 ‰ group owned a better osmoregulation than 23 ‰ group. • Different functions of anterior and posterior gills in salinity adaptation. [ABSTRACT FROM AUTHOR]

Ammonia is a major aquatic environmental pollutants. However, the underlying molecular mechanism of ammonia-induced toxicity is not fully understood. In this study, we investigated the physiological response and molecular mechanism in mud crab (Scylla paramamosain) exposed to the acute total ammonia (30 mg L−1) for 48 h. The results shown that ammonia exposure induced oxidative stress, and subsequently led to cytological damage and DNA damage. Transcriptome analysis was applied to investigate the key genes and pathways involved in the responses to ammonia exposure. A total of 722 differentially expressed genes (DEGs) (526 up-regulated and 196 down-regulated) were identified. DEGs mainly involved in pathways including metabolism, cellular processes, signal transduction and immune functions. Additionally, transcriptome analysis revealed that ATM/p53-Caspase3 pathway involved in apoptosis induced by ammonia stress. These results provided a new insight into the mechanism of the potential toxic effects of ammonia on crustaceans. • Ammonia exposure induced oxidative stress, and led to cytological damage and DNA damage. • Some genes involved in response to environmental stress were found. • ATM/p53-Caspase3 pathway could be involved in response to ammonia exposure. [ABSTRACT FROM AUTHOR]

Benzophenones (BPs) are commonly used in personal care products like sunscreens and are increasingly being released into the environment, raising concerns about their potential ecotoxic effects. BPs as emerging environmental contaminants, little is known about their toxic effects on estuarine organisms. This study firstly investigated the toxic effects of five commonly used BPs on mud crabs (Scylla paramamosain). The crabs were exposed to varying concentrations of BPs for 14 days. The results showed that BPs caused damage to antioxidant systems in crabs. Transcriptome sequencing revealed that BP-3 and BP-1 had a greater impact on the crabs compared to the other BPs. Specifically, BP-1 and BP-3 caused severe damage to organelles and ribosomes. BP affected catalytic activity and hydrolase activity, BP-2 affected phosphoenolpyruate carboxykinase activity, and BP-4 affected tRNA aminoacylation and hydrolase activity. These findings can enhance our understanding of the ecotoxicity of BPs and may help to protect estuarine ecosystems. [Display omitted] • Comparative analysis of five BPs' toxic effects on crabs was firstly conducted. • The five BPs caused different gene response patterns in S. paramamosain. • BP-3 and BP-1 exhibited higher hepatotoxicity on S. paramamosain. • BPs impacted the antioxidant system in S. paramamosain. • BPs influenced the apoptosis signaling in S. paramamosain. [ABSTRACT FROM AUTHOR]

Vitellogenesis in crustaceans is controlled by several steroid hormones. In humans, the expression of SF-1 , a gene that regulates gonadal development and the synthesis of steroid hormones, is affected by DDX20. However, how the homologous gene FTZ-F1 is regulated by DDX20 and its association with vitellogenesis remains unknown in the mud crab Scylla paramamosain. In this study, SpDDX20 and SpFTZ-F1 were identified in the transcriptome of mature ovarian tissue from the mud crab. qRT-PCR results revealed that the expression levels of SpFTZ-F1 and SpVTG in the ovaries of crab in the experimental group injected with dsDDX20 (EO) were significantly higher (P < 0.05) than those in the negative control group injected with dsEGFP (NO) and the blank control group injected with SPSS (BO). The differentially expressed genes (DEGs) identified by comparative transcriptome analysis of the EO group and NO group were enriched into five pathways related to ovarian steroidogenesis. The expression of CYP17 , CYP3A4 , CYP1A1 and 3β-HSD were up-regulated in pathways related to steroid hormone production and biosynthesis. The expression of the INSR , IRS and PI3K genes in the insulin signaling pathway were significantly increased (P < 0.05). The expression level of the TGF-β gene was up-regulated (P < 0.05) in the transforming growth factor pathway, whereas the expression level of the Smad2 gene was down-regulated (P < 0.05). The expression of GnRHR , GS , AC and PKA genes in the gonadotropin-releasing hormone signaling pathway were up-regulated. Our data provide a foundation for investigating the relationship between DDX20 and FTZ-F1 in the regulation of vitellogenin expression in S. paramamosain. [Display omitted] • Full-length cDNA of SpDDX20 and SpFTZ-F1 were cloned and characterized from Scylla paramamosain. • The expression of SpDDX20 and SpFTZ-F1 had tissue and gender specificity. • The expression level of SpFTZ-F1 was up-regulated after SpDDX20 interference. • Five ovarian steroidogenesis pathways were differentially expressed after SpDDX20 knockdown. • The expression level of SpVTG was up-regulated after knockdown of SpDDX20. [ABSTRACT FROM AUTHOR]

The mud crab (Scylla paramamosain) is an economically important crab species that is distributed along the southern coast of China. Previously we reported that various morphological types of mud crabs differentially adapt to temperature changes. This study investigates the effects of temperature on morphs with one or two spines (Sp1 and Sp2, respectively) on the outer margin of the carpus of cheliped at a low temperature (8 °C) and a control temperature (20 °C). The hepatopancreas were the transcriptome source, and a total of 81,853 unigenes were obtained by sequencing, with an average length of 420 bp, and an N 50 of 1460 bp. Of these, 22.33 % were known genes. Under low-temperature stress, there were 361 differentially expressed genes (DEGs) between the two morphs; 96 and 265 were up- and down-regulated genes, respectively. There were no DEGs between the morphs at 20 °C. Functional enrichment analysis revealed that the DEGs encoded abundant metallocarboxypeptidase activity, extracellular space, proteolysis, and sequence-specific DNA binding, and were further enriched in signal pathway components, including ubiquinone and other terpenoid-quinone biosynthesis, phenylalanine metabolism, MAPK signaling pathway, apoptosis, and other signaling pathways. The gene expressions of acid phosphatase (ACP), chymotrypsin (CHY), serine carboxypeptidase (SCP), and trypsin (TRY) under low-temperature stress were detected. The expressions of ACP , CHY , and SCP gradually decreased with time. The ACP , CHY , SCP , and TRY gene expression of the Sp1 morph was lower than that of the Sp2 morph; however, the ACP gene expression of the Sp1 morph was higher than that of the Sp2 morph at several time points. In conclusion, adaptability differences between the morphs to low-temperature stress were confirmed, which will enable the selection of cold-tolerant, high-quality varieties of mud crabs for breeding. [Display omitted] • Differential response to low-temperature stress in two morphs was analyzed using RNA-seq. • There was no DEGs between two morphs at 20 °C while there were 361 DEGs between two morphs at 8 °C. • At low-temperature stress, the expression of the digestive enzyme genes in two morphs was significant difference. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in environments, and they can negatively affect aquatic animal health. After 7 days of PCBs exposure, the activities of catalase, phenoloxidase, and superoxide dismutase and the total hemocyte count in the haemolymph were significantly decreased and the reactive oxygen species (ROS) content and phagocytic rate of hemocytes were significantly increased in mud crab Scylla paramamosain. Additionally, serum lysozyme, glutathione, glutathione-S-transferase, and glutathione peroxidase activities were significantly down-regulated in mud crab after PCBs exposure. The survival rate of crab hemocytes significantly declined as the PCBs concentration increased, indicating that PCBs had a cytotoxic effect on hemocytes. Exposure to increasing concentrations of PCBs also increased the degree of DNA damage in crab hemocytes. After PCBs exposure, the expression levels of P53 and caspase-3 in hemocytes were significantly up-regulated, which suggests that apoptosis was occurring. The apoptosis rate of hemocytes was up-regulated as the PCBs concentration increased, indicating that apoptosis was induced by the PCBs-activated caspase-3 pathway. These data suggest that exposure to PCBs hampered the immune response of mud crabs, most likely by (1) inducing ROS, causing DNA damage, and reducing the viability of hemocytes, (2) reducing the activities of antioxidant enzymes, and (3) inducing phagocytosis and apoptosis of hemocytes. And the final result of PCBs-induced immunotoxicity to mud crabs is the reduced bacterial disease resistance and survival rate of crabs under Vibrio alginolyticus challenge. [Display omitted] • PCBs exposure reduced the activities of antioxidant enzymes in mud crabs. • PCBs exposure induced ROS, caused DNA damage, and reduced hemocyte viability. • PCBs-induced immunotoxicity reduced bacterial disease resistance of crabs. [ABSTRACT FROM AUTHOR]

The hepatopancreas is the key organ involved in energy storage, immune response, and metabolism during crustacean molting, yet the underlying molecular mechanisms in the hepatopancreas that regulate molting remain unknown. In the present study, we conducted a comprehensive proteomic analysis in the hepatopancreas and quantified 1527 proteins, of which 193 changed significantly in abundance among three molting stages (pre-molt: PrM, post-molt: PoM, and inter-molt: InM) of Scylla paramamosain using iTRAQ-coupled LC-MS/MS. Ten exoskeleton and cuticle reconstruction proteins, such as chitinase, cuticle protein and myosin heavy chain, were found change significantly in abundance between PoM and PrM. Six energy metabolism proteins such as mitochondrial cytochrome c oxidase, cytochrome b -c1 and cAMP-dependent protein kinase with positive loadings showed a higher abundance in InM than PoM. In addition, all differentially abundance proteins (DAPs) were annotated for GO function and KEGG pathway analysis. GO analysis demonstrated function subcategories mainly including thiamine metabolism, complement and coagulation cascades, endocrine, shigellosis, salmonella infection, and other factor-regulated calcium reabsorption. The KEGG pathway enrichment analysis indicated that the DAPs were mainly involved in reconstruction of the exoskeleton and cuticle, energy reserves, metabolism, and immune response during the molting process. The results for the proteins and key pathways involved in the molting process provide fundamental molecular evidence that will improve our understanding of morphological and metabolism variation in the molting cycle and will serve as a potential blueprint for future study on molecular mechanism of molting in crustaceans. [Display omitted] • A comprehensive iTRAQ-based proteome of the hepatopancreas was obtained. • It provide molecular evidence for the proteins and pathways involved in molting. • It provides important references for study of molting regulation in crustaceans. • It will help to improve the performance of Scylla paramamosain aquaculture. [ABSTRACT FROM AUTHOR]

The article discusses a study of the cell structure and seasonal changes of the androgenic gland (AG) of the mud crab Scylla paramamosain acquired from local fish markets in Hong Kong, China. The chemicals and techniques used in dissecting microscopy and histological observations are cited. A description of the cells in different parts of the AG is offered. The ultrastructure of AG cells in mature crabs is comparable to that of type II AG cells. Crabs demonstrated differences in morphology and histology of the AG including gland size and cell boundary.

Light intensity is one of the ecological factors that appreciably affects the metabolism of Scylla paramamosain during overwintering. This study adopted the isobaric tag for relative and absolute quantitation (iTRAQ) method to investigate metabolic changes of S. paramamosain under three illumination levels (0, 1.43 and 40.31 μmol m−2·s−1) for four months during indoor overwintering. The iTRAQ identified 3282 proteins, among which 267 exhibited significant differential expression (122 upregulated and 145 downregulated) in the low light group, and 299 with significant differential expression (252 upregulated and 47 downregulated) in the high light group. Analysis of these results showed that there were different metabolic regulatory patterns under different light intensities. Low light is more conducive to the survival of S. paramamosain , which needs to produce and consume relatively less energy to sustain physiological activities. Thus, the essential proteins associated with physiological activities were significantly upregulated, while those related to energy production were significantly downregulated. In contrast, high light exerts a certain stress on the survival of S. paramamosain and required more energy to cope with this stress, which forced a significant upregulation of proteins related to stress response and energy production. The findings of this study highlighted the metabolic regulatory mechanisms of S. paramamosain under different light intensities. • The proteomics of S. paramamosain hepatopancreas was analyzed under different light intensities. • Metabolic regulation might be an effective strategy through which S. paramamosain responds to different light intensities. • There were different metabolic regulatory patterns under different light intensities. • S. paramamosain produce and consume relatively less energy to sustain physiological activities under low light condition. • High light exerts a certain stress on the survival and required more energy to cope with this stress. [ABSTRACT FROM AUTHOR]