Mud Crab Scylla Paramamosain Research Articles

Regulation of vtg and VtgR in mud crab Scylla paramamosain by miR-34.

Vitellogenin (Vtg) is the precursor of major yolk protein and plays a crucial role in the maturation of oocytes and the production of eggs in oviparous animals. Vitellogenin receptor (VtgR) mediates the transport of Vtg explicitly to oocytes in the membrane. In a previous study, we found that miR-34 can regulate the expression of some eyestalk genes and affect reproduction in mud crab Scylla paramamosain, one of the most important economic crabs on the coasts of southern China. In this study, firstly, we found that miR-34 can target at 3'-UTR of Vtg and VtgR genes by using bioinformatic tools and predicted miR-34 might depress the expression of Vtg and VtgR. Secondly, the relative luciferase activity of HEK293T cells co-transfected with miRNA mimic and pmir-RB-REPORTTM-Vtg/VtgR-3'UTR was significantly lower than those of cells co-transfected with mimic NC and pmir-RB-REPORTTM-Vtg/VtgR-3'UTR. Finally, in vivo experiments showed that agomiR-34 could repress the expression of Vtg and VtgR genes, while Antigomir-34 could promote the expression of these two genes. These results confirm our hypothesis and previous published results that miR-34 may indirectly regulate ovarian development by binding to the 3'-UTR of Vtg and VtgR genes and inhibiting their expression.

Role of short neuropeptide F in regulating eyestalk neuroendocrine systems in the mud crab Scylla paramamosain

The eyestalk ganglion serves as an essential endocrine organ in Crustacea. Although the short neuropeptide F (sNPF) is involved in a broad range of physiological functions via its counterpart receptor (sNPFR), its roles in regulating the crustacean hyperglycemic hormone (CHH) family in the eyestalk ganglion is still unclear. In this study, reverse transcription PCR indicates that the sNPF was most highly expressed in the eyestalk ganglion, whereas sNPFR was expressed in 11 tissues of the mud crab Scylla paramamosain, including eyestalk ganglion. Immunohistochemistry analyses further display that sNPF immunoreactive neurons were localized in the X-organ of eyestalk ganglion. Moreover, the stimulatory effect of sNPF on the gene expression of vitellogenesis-inhibiting hormone (VIH), molt-inhibiting hormone (MIH), and crustacean hyperglycemic hormone (CHH) in the eyestalk ganglion was confirmed by in vivo experiment. In contrast, RNA interference by injection of sNPF dsRNA or sNPFR dsRNA into crabs significantly reduced VIH, MIH, and CHH expressions in the eyestalk ganglion, respectively. This study first reported that sNPF might play roles in the reproduction, molting and glucose metabolism in S. paramamosain via regulating CHH family neuropeptides in the eyestalk ganglion.

The effects of feeding ration and cheliped autotomy on the growth and expression of ecdysteroid receptor in early juvenile mud crabs, Scylla paramamosain

This study investigated the combined effects of feeding ration and cheliped autotomy on the intermolt duration, molting success, molt increments in size and weight, and ecdysteroid receptor gene (SpEcR) expression of early juvenile mud crab Scylla paramamosain. Newly molted second stage juvenile crabs (C2) were subjected to four feeding conditions; optimal, suboptimal (1/2 optimal), low (1/4 optimal) ration and starvation, and autotomy (intact vs. cheliped autotomy) in a 4 × 2 factorial design until all crabs successfully molted or died. A significant interaction of feeding ration and cheliped autotomy on intermolt duration was identified. With reduced feeding ration, both intact and cheliped autotomized crabs showed increased time and desynchrony of molting, but decreased carapace size and body weight. Importantly, all crabs with different feeding rations even the low ration had high rates of molting success (> 95%), while the crabs subjected to starvation died without molting. When fed optimal ration, the mean intermolt duration of the cheliped autotomized crabs was significantly prolonged, while no such effect was found between autotomized and intact crabs subjected to suboptimal or low feeding ration. The qRT-PCR revealed that the expression of SpEcR showed a general trend of inhibited by reduced feeding ration, which was consistent with observed significantly increased intermolt duration. Interestingly, the transcript level of SpEcR was only significantly affected by cheliped autotomy under the optimal and suboptimal feeding rations but not for the low feeding ration. Together, the results of this study suggest that the S. paramamosain early juveniles have a strong tolerance for fluctuations in food availability. In addition, the availability of food and limb autotomy could significantly affect growth, molting duration and synchrony of the crabs, which appeared to reflect in SpEcR expression level that involved in the regulation of molting and limb regeneration process of the juvenile crabs.

Functional characterisation and comparative analysis of two C-type lectins with different key motifs from mud crab

C-type lectins are pattern recognition receptors (PRRs) involved in innate immunity. They possess one or more carbohydrate recognition domains (CRDs) belonging to Ca2+-dependent carbohydrate binding proteins. Herein, two C-type lectins were identified from the mud crab Scylla paramamosain. The open reading frame (ORF) of SpCTL-E encodes 160 amino acids including a CRD and a signal peptide, while the SpCTL-F ORF encodes a 244 amino acid polypeptide with a signal peptide and a CRD, and the key motifs for carbohydrate binding specificity are Asp-Pro-Asn (DPN) and Gln-Pro-Asp (QPD), respectively. DPN is a newly discovered motif, while QPD is typical of C-type lectins. The binding specificity toward different pathogen-associated molecular patterns (PAMPs) was analysed, and both bound three PAMPs: lipopolysaccharide (LPS), glucan (GLU) and peptidoglycan (PGN). SpCTL-F bound more strongly than SpCTL-E. SpCTL-E and SpCTL-F bound to five and seven microbial species, respectively, both agglutinated Gram-negative bacteria and fungi, and both promoted the phagocytosis activity of hemocytes toward Escherichia coli, and both enhanced the encapsulation activity of hemocytes towards Ni-NTA beads. SpCTL-E inhibited the growth of Micrococcus luteus and E. coli, while SpCTL-F also inhibited Vibrio parahaemolyticus. Thus, SpCTL-E and SpCTL-F are important PRRs with a broad nonself-recognition spectrum and play a key role in pathogen elimination.

SpBNIP3 regulates apoptosis and autophagy in mud crab (Scylla paramamosain) during white spot syndrome virus infection

BNIP3 (BCL2 and adenovirus E1B 19-kDa-interacting protein 3), which is a pro-apoptotic protein in the BCL-2 family involves a variety of cell signaling pathways, including mitochondrial dysfunction, mitochondrial autophagy, and apoptosis in vertebrates. However, the role of BNIP3 in the regulation of apoptosis and/or autophagy in crustaceans suffering virus infection is still limited. In this study, the mud crab (Scylla paramamosain) BNIP3 (SpBNIP3) was identified and studied to elucidate its association with the white spot syndrome virus (WSSV) infection. SpBNIP3 was widely expressed in all tested tissues and significantly down-regulated in the hemocytes of mud crab after WSSV infection. Knockdown of SpBNIP3 using RNA interference increased the apoptosis rate and Caspase 3 activity but decreased the mitochondrial membrane potential and autophagy levels, as well as viral copy number in mud crabs infected with WSSV. Additionally, the relationship between the viral infection and the autophagy of hemocytes was observed. The level of autophagy was reduced upon WSSV infection, and the activation of autophagy enriched the viral copy number. Taken together, the results of this study provide a new finding on the mechanism that SpBNIP3 may participate in the WSSV infection through the regulation of apoptosis and autophagy processes in mud crabs.

The mechanism of semicarbazide (SEM) exposure causes immunosuppression and reduces disease resistance of marine crustacean species, Scylla paramamosain

Semicarbazide (SEM) is a common pollutant in the marine environment. It can cause cell mutation, carcinogenesis, and teratogenesis, threatening the health and survival of marine species. In this study, the immunotoxicity of SEM was investigated in a marine crustacean species, the mud crab Scylla paramamosain. After seven days of exposure to 0.2 μg/L, 2 μg/L, or 20 μg/L concentrations of SEM, the effects of SEM on hemocytes and immune function were analyzed in S. paramamosain. The results showed that the hemolymph color deepened and total hemocyte count (THC) was down-regulated significantly with increasing SEM concentration. Meanwhile, tissue sections showed cell infiltration, cytoplasmic vacuolization, and cell steatosis. The survival rate of hemocytes decreased after SEM treatment in vitro, which revealed that SEM showed a cytotoxic to hemocytes. Superoxide dismutase (SOD), glutathione (GSH), phenoloxidase (PO) and catalase (CAT) activity decreased with increasing SEM concentration, while the activity of glutathione peroxidase (GSH-Px) was increased compared with the control group. Similarly, intracellular ROS content increased to about 1.2-, 1.3-, and 2-fold that of the PBS group after exposure to 0.2, 2, and 20 μg/L SEM, respectively. There was a trend of significant up-regulation of p53 and caspase-3 with increasing concentrations of SEM identified by Q-PCR. Meanwhile, the hemocytes apoptosis rate were increased with the SEM concentration, which induced by caspase-3 pathway activated by SEM. The phagocytic activity of hemocytes decreased with increasing SEM concentration. The challenge experiment illustrated that SEM exposure reduced the resistance of mud crab to Vibrio alginolyticus. Our results demonstrated that SEM exposure could inhibit the immune function by causing cell damage, inducing reactive oxygen species (ROS), reducing the activity of antioxidant enzymes and inducing hemocytes apoptosis in a marine crustacean species. SynopsisSEM in seawater could inhibit the immune function and threaten the survival in crustaceans.

Mechanism of Cadmium Exposure Induced Hepatotoxicity in the Mud Crab (Scylla paramamosain): Activation of Oxidative Stress and Nrf2 Signaling Pathway.

Cadmium, one of the most toxic heavy metals, can cause severe oxidative damage to aquatic animals. However, the mechanism whereby the mud crabs respond to cadmium exposure remains unclear. This study investigated the effects of cadmium exposure on oxidative stress and histopathology changes and evaluated the role of the Nrf2 signaling pathway in regulating responses to cadmium-induced hepatotoxicity were investigated in mud crabs. Mud crabs were exposed to 0, 0.01, 0.05, and 0.125 mg/L cadmium for 21 d. The present results indicated that cadmium exposure increased hydrogen peroxide (H2O2) production, lipid peroxidation and tissue damage, but decreased the activity of superoxide dismutase (SOD) and catalase (CAT), and caused lipid peroxidation and tissue damage. The results of an integrated biomarker index analysis suggested that the toxicity of cadmium was positively related to cadmium concentration. The expression levels of the Nrf2 signaling pathway (Nrf2, metallothionein, and cytochrome P450 enzymes) were up-regulated after cadmium exposure. Silencing of Nrf2 in vivo decreased antioxidant gene (SOD, CAT, and glutathione S-transferase) expression, suggesting that Nrf2 can regulate antioxidant genes. Knocking down Nrf2 in vivo also significantly decreased the activity of SOD and CAT after cadmium exposure. Moreover, silencing of Nrf2 in vivo enhanced H2O2 production and the mortality rates of mud crabs after cadmium exposure. The present study indicated that cadmium exposure induced hepatotoxicity in the mud crab by increasing H2O2 content, which decreased the antioxidant capacity, leading to cell injury. In addition, the Nrf2 is activated to bound with antioxidant response element, initiating the expression of antioxidant enzyme genes during cadmium induced hepatotoxicity in the mud crabs.

The Anticancer Activity Conferred by the Mud Crab Antimicrobial Peptide Scyreprocin through Apoptosis and Membrane Disruption.

Scyreprocin is an antimicrobial peptide first identified in the mud crab Scylla paramamosain. Herein, we showed that its recombinant product (rScyreprocin) could significantly inhibit the growth of human lung cancer NCI-H460 cells (H460), but showed no cytotoxicity to human lung fibroblasts (HFL1). rScyreprocin was a membrane-active peptide that firstly induced the generation of reactive oxygen species (ROS) in H460, and led to endoplasmic reticulum stress and Ca2+ release, which resulted in mitochondrial dysfunction and subsequently activation of caspase-3 cascades, and ultimately led to apoptosis. The comprehensive results indicated that rScyreprocin exerted anticancer activity by disrupting cell membrane and inducing apoptosis. The in vivo efficacy test demonstrated that intratumoral injection of rScyreprocin significantly inhibited the growth of H460 xenografts, which was close to that of the cisplatin (inhibition rate: 69.94% vs. 80.76%). Therefore, rScyreprocin is expected to become a promising candidate for the treatment of lung cancer.

Cloning, expression, and function of the Spdmrt-like gene in Scylla paramamosain.

The mud crab Scylla paramamosain is an economically important species for aquaculture in China and has sexually dimorphic between females and males. Understanding sex differentiation in this species is essential for the development of monosex aquaculture. The Dmrt genes play a vital role in sex differentiation in animals. In this study, two dmrt-like transcript variants, Spdmrt-like-tv1 and Spdmrt-like-v2, were cloned. SpDmrt-like-tv1 contained a DM domain, while SpDmrt-like-tv2 contained a DM and a DMA domain. Spdmrt-like-tv1 and Spdmrt-like-tv2 were both specifically expressed in testis. During testicular development, the expression level of Spdmrt-like-tv1 increased from stage I to stage II (P > 0.05) and then decreased from stage II to stage III (P < 0.05). The expression level of Spdmrt-like-tv2 in stages I and II was significantly higher than that in stage III (P < 0.05). During embryonic development, the expression level of Spdmrt-like-tv1 was higher in the mid-embryonic stage compared with the early and late stages, but the differences were not significant. Moreover, the expression level of Spdmrt-like-tv2 was stable and remained high throughout embryonic development. Furthermore, the expression level of Spdmrt-like-tv2 was significantly higher than that of Spdmrt-like-tv1. Knockdown of Spdmrt-like variants indicated that the regulative target gene of Spdmrt-like-tv1 was Spsox21, and the regulative target genes of Spdmrt-like-tv2 were Spfoxl2 and Spsox21. Combined with the results in our previously published peer-reviewed articles that the expression of Spfoxl2 in the testis was significantly higher than that in the ovary, and Spfoxl2 negatively regulated Spvtg expression. Spsox21 played a role in the development and maintenance of testis as well as in the process of neural development and regulation of body segmentation. Therefore, we suggest that Spdmrt-like-tv1 and Spdmrt-like-tv2 might be involved in testicular development and embryonic development, and Spdmrt-like-tv2 might play more important roles in these two developmental processes by regulating the expression of Spfoxl2 and Spsox21 due to its high expression.

Effects of two natural diets on the biochemical compositions of post‐mating female mud crab ( Scylla paramamosain )

Understanding the effects of different natural diets on the growth performance and nutritional quality of mud crab Scylla paramamosain is important for both aquaculture and human nutrition perspectives. In the present study, female S. paramamosain were fed with two different natural diets, a marine bivalve species Potamocorbula rubromuscula (initial weight of the experimental crabs: 192.1 ± 29.2 g) and lizardfish Harpadon nehereus (initial weight of the experimental crabs: 188.1 ± 42.9 g) during the post-mating period. Furthermore, the weight gain ratio (WGR), specific growth rate (SGR), gonado-somatic index (GSI), hepatosomatic index (HSI), proximate compositions, total carotenoid content, amino and fatty acid profiles were investigated. Different diets affected HSI, carotenoid, lipid, amino acid and fatty acid contents in the claw muscle, hepatopancreas and ovary of female S. paramamosain. However, different diets did not affect the growth parameters including WGR, SGR and GSI. Crabs fed with P. rubromuscula had significantly higher amino acid content in the claw muscle, hepatopancreas and ovary, but lower HSI value and lipid content in the hepatopancreas and ovary compared with the crabs fed with H. nehereus. The carotenoid content was significantly higher in the hepatopancreas and ovary tissues of crabs fed with P. rubromuscula, whereas crab fed with H. nehereus displayed higher carotenoid content in the claw muscle. These results indicated that feeding S. paramamosain with P. rubromuscula could enhance amino acid contents (in claw muscle, hepatopancreas and ovary) and carotenoid contents in the hepatopancreas and ovary. Moreover, this study showed that the post-mating period is a critical period for nutritional deposition and a short feeding strategy during this period dramatically alters the body biochemical compositions.

Characterization of phosphofructokinase (PFK) from mud crab Scylla paramamosain and its role in mud crab dicistrovirus-1 proliferation

Phosphofructokinase (PFK), the key enzyme of glycolysis, can catalyze the irreversible transphosphorylation of fructose-6-phosphate forming fructose-1, 6-biphosphate. In the present study, a PFK gene from the mud crab Scylla paramamosain, named SpPFK, was cloned and characterized. The full length of SpPFK contained a 5′untranslated region (UTR) of 249 bp, an open reading frame of 2,859 bp, and a 3′UTR of 1,248 bp. The mRNA of SpPFK was highly expressed in the gill, followed by the hemocytes and muscle. The expression of SpPFK was significantly up-regulated after mud crab dicistrovirus-1 (MCDV-1) infection. Knocking down SpPFK in vivo by RNA interference significantly reduced the expression of lactate dehydrogenase after MCDV-1 infection. Furthermore, silencing of SpPFK in vivo increased the survival rate of mud crabs and decreased the MCDV-1 copies in the gill and hepatopancreas after MCDV-1 infection. All these results suggested that SpPFK could play an important role in the process of MCDV-1 proliferation in mud crab.

Characterization and comparison of two C-type lectins with novel key motifs from mud crab Scylla paramamosain

Characterization and comparison of two C-type lectins with novel key motifs from mud crab Scylla paramamosain

Two Male-Specific Antimicrobial Peptides SCY2 and Scyreprocin as Crucial Molecules Participated in the Sperm Acrosome Reaction of Mud Crab Scylla paramamosain.

Antimicrobial peptides (AMPs) identified in the reproductive system of animals have been widely studied for their antimicrobial activity, but only a few studies have focused on their physiological roles. Our previous studies have revealed the in vitro antimicrobial activity of two male gonadal AMPs, SCY2 and scyreprocin, from mud crab Scylla paramamosain. Their physiological functions, however, remain a mystery. In this study, the two AMPs were found co-localized on the sperm apical cap. Meanwhile, progesterone was confirmed to induce acrosome reaction (AR) of mud crab sperm in vitro, which intrigued us to explore the roles of the AMPs and progesterone in AR. Results showed that the specific antibody blockade of scyreprocin inhibited the progesterone-induced AR without affecting intracellular Ca2+ homeostasis, while the blockade of SCY2 hindered the influx of Ca2+. We further showed that SCY2 could directly bind to Ca2+. Moreover, progesterone failed to induce AR when either scyreprocin or SCY2 function was deprived. Taken together, scyreprocin and SCY2 played a dual role in reproductive immunity and sperm AR. To our knowledge, this is the first report on the direct involvement of AMPs in sperm AR, which would expand the current understanding of the roles of AMPs in reproduction.

Dietary chromium could improve growth, antioxidant capacity, chromium accumulation in tissues and expression of genes involved into glucose and lipid metabolism in juvenile mud crab Scylla paramamosain

Chromium (Cr) is an essential micronutrient for all animals, which is also an important component of glucose tolerance factor. The present study was conducted to evaluate the effect of dietary Cr levels on growth, Cr accumulation in tissues, glucose and lipid metabolism and insulin signal pathway of juvenile mud crab. Six isonitrogenous and isolipidic diets were formulated to contain 1.4 (basal diet), 1.7, 2.0, 2.2, 2.6 and 3.7 mg kg−1 Cr, respectively. The results indicated that crabs fed with 2.2 and 2.6 mg kg−1 Cr diets had the highest percent weight gain (PWG) and specific growth rate (SGR) among all treatments. Cr concentration in hepatopancreas significantly increased with increase of dietary Cr levels. Crabs fed with 3.7 mg kg−1 Cr diet exhibited lower antioxidant enzyme activities and higher malondialdehyde (MDA) in hepatopancreas and hemolymph than those fed the other diets. Crabs fed the diets with 2.2 and 2.6 mg kg−1 Cr showed higher activities of hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK). The expression levels of genes related to insulin signaling pathway, glycolysis and fat synthesis, glycolipid metabolism (such as phosphatidylinositol 3-kinase (pi3k), hexokinase (hk), and fatty acid synthase (fas)) in hepatopancreas were significantly up-regulated. The expression levels of genes related to gluconeogenesis and lipolysis such as fructose-1,6-bisphosphatase (fbp) and carnitine palmitoyltransferase 1 (cpt1) were significantly down-regulated in crabs fed with optimal Cr diets. In conclusion, the optimal dietary Cr requirement was estimated to be 2.34 mg kg−1 for juvenile mud crab based on two slope broken-line regression analysis of PWG against dietary Cr levels, the results of present study indicated that optimal dietary Cr promoted the growth and Cr accumulation in tissues, and modulated insulin signaling pathway to trigger glycolysis and glycogenesis to maintain glucose homeostasis.

Light Spectrum Impacts on Growth, Molting, and Oxidative Stress Response of the Mud Crab Scylla paramamosain

An 8 weeks trial was performed to test the effects of light spectra [full-spectrum, violet (405 nm), blue (470 nm), cyan (500 nm), green (525 nm), yellow (570 nm), and red (625 nm)] on growth performance, molting, antioxidant capacity, stress response and expression of molting, and apoptosis-related genes in Scylla paramamosain. Results showed that spectrum had a significant effect on S. paramamosain physiology. Compared to blue light, crabs exposed to violet light had a significantly lower survival rate (79.5 ± 3.6% vs. 94.9 ± 3.6%), weight gain (49.2 ± 5.4 vs. 67.6 ± 6.7), molt frequency (4.2 ± 0.2 vs. 4.5 ± 0.1), and extended intermolt intervals between instar 1 and 2 stages (C1–C2) (6.3 ± 0.3 vs. 5.0 ± 0.1 days). Expression of the molt-inhibiting hormone (mih) gene was upregulated in crabs reared under violet light. According to the regression analysis, maximum SGR would be at 449.97 nm. Crabs exposed to blue light also had lower melatonin levels than under full-spectrum and lower cortisol levels than violet and yellow groups. Regarding oxidative stress, crabs in full-spectrum had lower H2O2 and MDA contents, however, no significant difference was found in total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) in hepatopancreas from crabs under different spectra. Gene expression of hsp40, hsp70, hsp90 were down-regulated in crabs exposed to the full-spectrum light group. Regarding apoptosis-related genes, bcl-2 gene expression in crabs under cyan and the cox IV and caspase 3 in green were upregulated, suggesting cyan light may inhibit, while green light may promote apoptosis. Taken together, these results suggest that blue or cyan light would promote growth performance, while full-spectrum light could reduce stress response in S. paramamosain.

ATP catabolism and bacterial succession in postmortem tissues of mud crab (Scylla paramamosain) and their roles in freshness

The seafood microbiome is highly diverse and plays an essential role in the spoilage of seafood. Nevertheless, how such a diverse microbiome influences freshness of mud crab (Scylla paramamosain) remains unclear. Here we investigated the postmortem ATP catabolism and succession of the bacterial community in the hepatopancreas and muscle of S. paramamosain using a high-performance liquid chromatography method and 16S rRNA gene amplicon sequencing. Our results showed a tissue-dependent change in ATP catabolism determinized the differences in the changes of nucleotide freshness indices of hepatopancreas and muscle over postmortem time of mud crab. The muscle K value could be used as an optimal nucleotide freshness indicator for the freshness of mud crab, with a proposed threshold of 20%. From a microbiota perspective, a more significant bacterial community change was observed in the muscle than in the hepatopancreas. These changes could result in a close relationship between ATP and its catabolites and microbial taxa in the muscle. Moreover, Photobacterium, Peptostreptococcaceae, average path distance, OTU richness, and Shannon index of muscle bacterial community markedly contributed to K value. These findings suggest that the mud crab of 4 h postmortem at room temperature is still edible. Notably, the importance of microbial community composition and interaction for the spoilage of mud crab should be carefully considered.

The Role of microRNA-133 in Hemocyte Proliferation and Innate Immunity of Scylla paramamosain.

MicroRNAs (miRNAs) are important signaling regulators that are involved in regulating the innate immunity of crustacean. However, few studies focus on the role of crustacean miRNAs in the cellular immunity have been reported. In this study, we showed that the expression of miR-133 was significantly up-regulated in the mud crab Scylla paramamosain after infection by white spot syndrome virus (WSSV) or Vibrio parahaemolyticus. The anti-miRNA oligonucleotide AMO-miR-133 was used to knock down miR-133 expression in S. paramamosain. The number of WSSV copies increased significantly in WSSV-infected crabs after miR-133 knockdown. Knockdown of miR-133 also enhanced the mortality rates of WSSV-infected and V. parahaemolyticus-infected mud crabs, and it significantly enhanced the expression of the astakine, which was confirmed by real-time quantitative PCR and western blot analysis. The data also indicate that miR-133 may affect hemocyte proliferation in S. paramamosain by regulating astakine expression. miR-133 Knockdown enhanced the apoptosis or phagocytosis of crab hemocytes, and increased the mortality of mud crabs after WSSV or V. parahaemolyticus infection. These results indicate that miR-133 is involved in the host immune response to WSSV and V. parahaemolyticus infection in mud crabs. Taken together, our research provides new insights for the control of viral or vibrio diseases in S. paramamosain.

SpgC1qR interacts with WSSV VP28 exhibiting antiviral activity

Although human gC1qR is a multi-ligand binding protein with diverse biological functions, the functions of invertebrate gC1qR homologues remain largely unknown. In the present study, we characterized a novel gC1qR homologue, namely SpgC1qR, from mud crab Scylla paramamosain. SpgC1qR shared high identity and similar three-dimensional structure with human gC1qR. After challenge with White spot syndrome virus (WSSV), the transcripts of SpgC1qR were significantly increased, suggesting that SpgC1qR may be involved in antiviral immune response. To reveal the likely antiviral activity of SpgC1qR, the proliferation profile of WSSV in SpgC1qR-silenced crabs was examined. The result showed that knockdown of SpgC1qR by RNAi facilitated viral proliferation in vivo. This result was further confirmed by a SpgC1qR pre-incubation assay, in which pre-incubating WSSV particles with rSpgC1qR dramatically suppressed viral replication. Moreover, a GST pull-down assay revealed that SpgC1qR specifically bound to the viral envelope protein VP28. These findings clearly demonstrated that SpgC1qR specifically interacted with viral envelope protein VP28 and restricted WSSV replication, suggesting that it played a crucial role in anti-WSSV immune response of mud crab. This study provided new insights into the antiviral mechanism mediated by SpgC1qR and the biological functions of invertebrate gC1qR homologues.

Effect of Long-Term Low-Salinity Culture on the Survival, Growth, and Nutrient Composition of Mud Crab Scylla paramamosain

Effect of Long-Term Low-Salinity Culture on the Survival, Growth, and Nutrient Composition of Mud Crab Scylla paramamosain

Hepatopancreas transcriptomic and lipidomic analyses reveal the molecular responses of mud crab (Scylla paramamosain) to dietary ratio of docosahexaenoic acid to eicosapentaenoic acid

To investigate the metabolic response of mud crab Scylla paramamosain to dietary ratio of docosahexaenoic acid (DHA) to eicosapentaenoic acid (EPA), transcriptomic and lipidomic analyses were conducted on the hepatopancreas of crabs (initial weight 20.92 ± 0.56 g) fed for 8-week with diets having suboptimum (0.6) and optimal (2.3) DHA/EPA ratios. The analyses identified 358 up-regulated and 432 down-regulated differentially expressed genes, and 48 up-regulated and 30 down-regulated differential lipid molecules with 53% phosphatidylcholine, 14% phosphatidylethanolamine and 13% phosphatidylinositol. GO analysis, KEGG pathway enrichment and network of interaction analysis identified pathways of glycerophospholipid metabolism, PPAR signaling, oxidative phosphorylation, ribosome and thermogenesis as being significantly affected by dietary DHA/EPA ratio. Specifically, dietary DHA/EPA ratio regulated the expression of genes in lipid metabolism and PPAR signaling pathways such as fas, fabp-1/3, fatp, cptI and aco. Compared to the suboptimum ratio, the optimum dietary DHA/EPA ratio down regulated the gene experssion of phospholipase D1/2 and glycerol-3-phosphate O-acyltransferase in glycerophospholipid metabolism pathway, akt and s6 in mTOR pathway, ask1 in thermogenesis and non-alcoholic fatty liver disease pathway, and up regulated the pepck experssion in PPAR signaling pathway. Thus, dietary DHA/EPA ratio influence the lipid, protien and carbohydrate metabolism, immune response, and even the cell member structure. The findings improved our understanding of the impacts and molecular mechanisms of a nutritional challenge, in this case the dietary DHA/EPA ratio, increased basic knowledge of multi-omics analysis of in a commercially important crustacian species, the mud crab S. paramamosain, and provided the framework for further in-depth functional studies to promote sustainable aquaculture.