The growth and development of aquaculture organisms are significantly influenced by environmental variations shaped by different aquaculture systems. In this study, a 90-day controlled experiment was conducted to compare two pond culture setups for largemouth bass: with water hyacinth co-planted (FM group) and without (M group). As this experiment progressed, the FM group exhibited significantly superior water quality (p < 0.05) compared to the M group across multiple parameters, including total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH3-N), dissolved oxygen (DO) and transparency, among which, the difference in transparency was especially evident (p < 0.001). Subsequently, by 90 days, the fish body weight, condition factor, and gonadosomatic index (GSI) were significantly higher in the FM group than in the M group, with the GSI difference being particularly pronounced (p < 0.001). While the GSI of M group fishes ranged exclusively from 0.01 to 0.02 (M1), the FM group displayed a much-expanded GSI range of 0.01-0.06, with 21.4% at 0.01-0.02 (FM1), 48.1% at 0.02-0.03 (FM2), and 30.5% at 0.03-0.06 (FM3). Accordingly, omics analyses of ovarian tissues were conducted between the control (M1) and the high-performing groups (FM2 and FM3). The analyses identified significant enrichment of the glycerophospholipid metabolic pathway and a marked upregulation of the Mettl3 gene (log2FC = 12.59) in the FM2 and FM3 than the M1 group, and both the pathway and the Mettl3 gene were actively involved in growth, reproductive processes, and oocyte maturation. Given that water transparency was the most markedly improved parameter, our results indicate that it may be a key driver in upregulating ovarian glycerophospholipid metabolism and Mettl3 expression in largemouth bass, thereby promoting better growth and ovarian development.

Rice-fish co-culture systems, as compared to fish monoculture, offer a sustainable agriculture model that balances productivity with environmental conservation. While the important role of gut microbiome in fish growth and health is increasingly recognized, the impact of different farming practices on fish quality and their gut microbiome remains insufficiently understood. To address this gap, we conducted a comprehensive survey of 292 carps (Cyprinus carpio) raised in four rice-fish co-culture systems (RF) across China, comparing them with sitematched pond systems (PF). Through a combination of amplicon sequencing, metabolomic analysis, and bioinformatics, we investigated changes in carp quality, as well as alterations in gut microbiota and metabolites, and explored the potential links between them. Our results reveal that RF system significantly improve carp quality and alter gut metabolite profiles. Further analysis of gut microbial subgroup showed that RF co-culture induced homogenization in the community structure of rare microbial taxa. Ecological network analysis indicated that RF enhances the complexity and stability of microbial networks, particularly among rare taxa, which play a previously underestimated role in gut ecosystems. Community assembly analysis suggested that deterministic processes more strongly shape the microbial communities in carps from RF system, promoting habitat-dependent selection. By developing a bi-network model to explore host-microbe interactions, we identified key microbial taxa, such as Cetobacterium, that are closely associated with beneficial traits in carp quality. Overall, this study highlights the potential of Rice-fish co-culture to foster beneficial host-microbe interactions, providing a microbial ecological perspective on understanding aquaculture safety and sustainability.

To investigate the potential toxic mechanism of Microcystin-LR (MC-LR) on juvenile Eriocheir sinensis (E. sinensis), a toxicity test was conducted by injecting MC-LR into the 3rd pereiopod. Following injection, we evaluated alterations in immune response biomarkers, antioxidant status, lipid metabolism-related genes expression, and intestinal microbiota composition in the hepatopancreas and intestinal tissues of E. sinensis. The results of immune response showed that after injection of MC-LR, the serum complement C3 level in E. sinensis significantly decreased at 48 hours (P < 0.05), whereas complement C4 level increased considerably from 12 to 96 hours (P < 0.01). The phenoloxidase system (PO) showed an increasing trend from 6 to 96 hours (P < 0.05 or P < 0.01). The levels of TNF-α, IL-6 significantly increased at 6 and 12 hours (P < 0.05 or P < 0.01). Gene expression analysis showed that FASN gene in the hepatopancreatic tissue displayed a higher expression at both 6 and 12 hours post-exposure (P < 0.01), while ALDH and ACAA2 gene exhibited a consistent downward trend from 6 to 48 hours (P < 0.05), Additionally, the mRNA levels of MECR and ACSL demonstrated a pattern of initial downregulation, followed by an upregulation, and subsequent downregulation. The antioxidant status results revealed that the levels GSH and CAT increased first and then decreased, while the activity of SOD decreased first and then increased. Meanwhile, the MDA content showed an increasing trend. 16 S rDNA analysis showed that the intestinal microbial diversity in MC-LR treatment group was significantly higher relative to the control group (P < 0.01). Compared with the control group, the MC-LR group had a significantly higher relative abundance of Proteobacteria, Fusobacteria, and Actinobacteria (P < 0.05) and a significantly lower relative abundance of Firmicutes (P < 0.01). At genus level, the relative abundance of Acinnetobacter, Flavobacterium, Acidovorax, Paracoccus, Cloacibacterium, Gemmobacter, Aeromonas, and Dechloromonas in the intestine of MC-LR-treated group was significantly increased relative to the control group (P < 0.05 or P < 0.01), but the relative abundance of Lachnospiraceae_NK4A136_group was significantly decreased (P < 0.01). The results of the study demonstrated that MC-LR could induced oxidative stress, hepatopancreas tissue damage, and intestinal microbial imbalance in E. sinensis.

Probiotics is a promising solution for the green development of Eriocheir sinensis industry. To screen potential probiotics for E. sinensis, we investigate the role of dietary Lactobacillus parafarraginis (LP group), Bacillus subtilis (BS group) and their complexes (LB group) on the growth, molt, immunity and intestinal health of juvenile crab. After feeding for 28 days, we found a significant increase in body weight of probiotic group, with the highest in the LB group. ecdysone was significantly higher in the LB group, which in turn increased its growth efficiency. Probiotics significantly increased the antioxidant capacity and decreased MDA and aminotransferase levels. Probiotic complexes improved PO activity in E. sinensis and showed better immune performance. Interestingly, the relative abundance of potential pathogenic microorganisms Candidatus Bacilloplasma and Vibrio was reduced in the probiotic group. Protomicrobiota in the gut such as Tyzzerella, Pseudorhodobacter in BS, Coprobacillus, Rhodobacter in LP and unclassfied, ZOR006 in LB showed higher abundance. Probiotics protected the intestinal health and enhanced the immunity of E. sinensis by maintaining the abundance of native microbiota in the intestine and reducing the abundance of potential pathogenic bacteria. On the other hand, probiotics positively affected juvenile crab by regulating metabolic pathways such as cGMP PKG signaling pathway, mTOR signaling pathway, ABC transporter protein, and protein digestion and absorption. Metabolites such as L-glutamate were up-regulated in BS. Levels of amino acids and lysophosphatidylcholines were increased in LP. Metabolites such as 4-hydroxyquinoline and 3-formylindole etc. were up-regulated in LB. These results provide a basis for the use of L. parafarraginis and B. subtilis as probiotics in the ecological culture of E. sinensis.

Geographical traceability plays a crucial role in ensuring quality assurance, brand establishment, and the sustainable development of the crab industry. In this study, we examined the possibility of using gas chromatography-ion mobility spectrometry with multivariate statistical authenticity analysis to identify the origin of crabs from five sites downstream of the Yangtze River. Significant variations were observed in the levels of alcoholic flavor compounds in the hepatopancreas and muscles of crabs from different geographical locations, and a support vector machine exhibited discriminant ability with 100% accuracy. These flavor variations exhibited significant correlations with the types and concentrations of elements within the crabs, as well as with free amino acids. This study offers a practical approach for determining the geographical traceability of Chinese mitten crabs and elucidates the role of elements in flavor modulation, thereby providing innovative strategies to enhance the efficiency of crab farming.

This study investigated the toxicological mechanism of deltamethrin on Chinese mitten crab Eriocheir sinensis juveniles in fresh water. We first conducted an acute toxicity test, followed by laboratory methods to detect changes in immune-related indices in terms of antioxidant enzyme markers, lipid metabolism-related genes, and autophagy-related and apoptosis genes. The acute toxicity (96-h LC50) of deltamethrin to E. sinensis was 7.195 μg/L. After 48 h of exposure, serum showed elevated immune-related indices (P < 0.05) for alkaline phosphatase (AKP), acid phosphatase (ACP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), complement components C3 and C4, and the key pro-inflammatory cytokines interleukin-6, interleukin-1β, and tumor necrosis factor alpha (TNF-α). In hepatopancreas at 48 h, indicators related to the antioxidant system, namely superoxide dismutase (SOD) and glutathione (GSH), were significantly elevated, whereas nitric oxide and total antioxidant capacity (T-AOC) were decreased (P < 0.05). In contrast, lipid metabolism indices for triglyceride (TG), total cholesterol (TC), and malondialdehyde (MDA) were increased (P < 0.05). Transcriptomics and metabolomics revealed that exposure to deltamethrin disrupted the lipid metabolic process in the hepatopancreas mainly by altering fatty acid synthesis, amino acid metabolism, immune signaling, and autophagy activation, while the exposure increased the content of phospholipids and cholesterol but decreased the levels of amino acids and palmitoleic acid. Quantitative genetics revealed significantly aberrantly expressed (P < 0.05) lipid metabolism-related genes, including acc1, fasn, scd1, and pnpla2, all key genes involved in lipid accumulation. Deltamethrin exposure also significantly altered (P < 0.05) gene expression levels for Toll-like receptor (tlr), myeloid differentiation factor 88 (myd88), crustin1, anti-lipopolysaccharide factor isoform 3 (alf3), tumor necrosis factor alpha (tnf-α), and NF-κB transcription factor relish. Furthermore, deltamethrin activated the toll-like receptor/major myeloid differentiation response gene 88/nuclear factor kappa-light-chain-enhancer of activated B cells (TLR/MyD88/NF-kB) signaling pathway, which activates a nonspecific immune response in E. sinensis. Additionally, carnitine palmitoyltransferase 1 A (cpt1a), cytochrome c (cyt-c), adenosine 5'-monophosphate (amp)-activated protein kinase (ampk), the autophagosomal protein microtubule-associated protein 1 light chain 3c (lc3c), and the autophagy-related proteins beclin1, atg5, atg12 were significantly induced (P < 0.05) in the adenosine monophosphate-activated protein kinase/rapamycin (AMPK/mTOR) signaling pathway. These changes resulted in excess free radicals, causing oxidative stress in the mitochondrial membrane, promoting mitochondrial autophagy. The results confirm that deltamethrin exposure can induce hepatopancreatic injury by promoting mitochondrial autophagy, activating an immune response, and inhibiting lipid metabolism. Overall, this study provides multi-level information to reveal the toxic effects of deltamethrin on E. sinensis.

Public-private partnerships (PPPs) have emerged as an innovative model for the delivery of infrastructure and public services on a global scale. These collaborations, which unite businesses, governmental bodies, and civil society stakeholders, are actively advocated for their capacity to pool essential financial resources. Simultaneously, they offer a strategic approach to mitigating risks associated with sector-specific operations and addressing intricate developmental challenges. PPPs leverages wider resources and capabilities and could have greater impacts, which have been widely adopted in various sectors such as infrastructure, health, education, and environment. In recent years, PPPs have also emerged as a promising tool to promote the development of aquaculture sector, which is the fastest growing food production sector in the world. However, PPPs in aquaculture sector have yet not to be widely adopted or well understood. We address this research gap by describing a successful PPP model in aquaculture sector based on a case study of Hani Terrace integrated rice-fish farming system in China. This research analyzes the type, structures, partner roles and partnership of the Hani Terrace PPP model, and it also examines the major challenges encountered and the development outcomes achieved by these projects. The results showed that the Aquaculture PPP created positive outcomes for different parterners and stimulated increased economic, social and environmental benefits from targeted interventions. This research intends to offer valuable insights and recommendations for policymakers, practitioners, researchers, and local communities keen on advancing the PPP model within the aquaculture sector. Additionally, the research identifies gaps and outlines directions for future studies in PPP development in the aquaculture sector. The research results seek to enhance the comprehension of all stakeholders involved in crafting successful PPP initiatives and improving service delivery.

Salvianolic acid B (Sal B), as one of the main water-soluble components of Salvia miltiorrhizae, has significant pharmacological activities, including antioxidant, free radical elimination and biofilm protection actions. However, the protective effect of Sal B on Nile tilapia and the underlying mechanism are rarely reported. Therefore, the aim of this study was to evaluate the effects of Sal B on antioxidant stress, apoptosis and autophagy in Nile tilapia liver. In this experiment, Nile tilapia were fed diets containing sal B (0.25, 0.50 and 0.75 g·kg−1) for 60 days, and then the oxidative hepatic injury of the tilapia was induced via intrapleural injection of 50 g·kg−1 cyclophosphamide (CTX) three times. After the final exposure to CTX, the Nile tilapia were weighed and blood and liver samples were collected for the detection of growth and biochemical indicators, pathological observations and TUNEL detection, as well as the determination of mRNA expression levels. The results showed that after the CTX treatment, the liver was severely damaged, the antioxidant capacity of the Nile tilapia was significantly decreased and the hepatocyte autophagy and apoptosis levels were significantly increased. Meanwhile, dietary Sal B can not only significantly improve the growth performance of tilapia and effectively reduce CTX-induced liver morphological lesions, but can also alleviate CTX-induced hepatocyte autophagy and apoptosis. In addition, Sal B also significantly regulated the expression of genes related to antioxidative stress, autophagy and apoptosis pathways. This suggested that the hepatoprotective effect of Sal B may be achieved through various pathways, including scavenging free radicals and inhibiting hepatocyte apoptosis and autophagy.

Cyanobacterial blooms threaten the quality and safety of the Chinese mitten crab Eriocheir sinensis. A combination of microalgae and probiotics seems a promising way to prevent and control cyanobacterial blooms in aquaculture ponds. In E. sinensis cultivation, however, a related strategy is still lacking. To assess the potential combined effects of effective microorganisms (EM) and Chlorella vulgaris on regulating cyanobacterial blooms, in this study, we detected the alterations in the physiology of E. sinensis, as well as water quality and microbial compositions of E. sinensis culture ponds with cyanobacterial blooms. As a result, supplementary EM and C. vulgaris had no adverse effects on the growth or digestive or antioxidant ability of E. sinensis but improved the water quality of the pond by reducing total ammonia nitrogen and total nitrogen levels. We found an increase in bacterial diversity and evenness, while a decrease in the diversity of fungal and phytoplankton communities was related to supplementary EM and C. vulgaris. Interestingly, EM coupling C. vulgaris promoted the restoration of the bacterial and fungal community composition in cyanobacterial blooms ponds, particularly the increase of Mychonastes abundance and the decrease of Cyclotella. This study laid the foundation for the prevention and control of potential risks in aquaculture.

罗氏沼虾苗标粗可实现放养大规格虾苗,以提早成虾上市时间,获得更大规格商品虾,增强市场竞争力.然而在虾苗标粗过程中,养殖户为限制养殖成本一味增加养殖数量、提高饲料投喂量,从而造成残饵增多、水质恶化、苗种摄食减少,最终影响虾苗的蜕壳生长,导致标苗伤残率或死亡率过高,严重影响了标苗效果.

为明确饲料中添加刺五加(Acanthopanax senticosus)超微粉对吉富罗非鱼(Oreochromis niloticus)脂质沉积、抗氧化能力及肠道消化酶和微生物的影响,通过为期8周的饲养试验,在饲料中添加4‰的刺五加超微粉(中草药添加剂),对比研究饲料添加刺五加后吉富罗非鱼肠道消化酶、肝脏生化指标和肠道微生物组成的变化.结果表明:(1)饲料添加4‰的刺五加超微粉可以显著提高肠道消化酶(淀粉酶、脂肪酶和胰蛋白酶)含量,罗非鱼生长速度和饲料利用效率均显著升高;(2)饲料添加4‰的刺五加超微粉可以显著降低肝脏甘油三酯(Triglyceride,TG)和总胆固醇(Total cholesterol,TC)水平,同时肝脏丙二醛(Malondialdehyde,MDA)含量降低、超氧化物歧化酶(Superoxide dismutase,SOD)活性升高;(3)饲料添加4‰的刺五加超微粉可以显著影响肠道微生物组成,提升肠道微生物alpha多样性,部分多样性指数与淀粉酶、脂肪酶、SOD显著正相关,与TC、TG显著负相关;(4)变形菌门(Proteobacteria)、梭杆菌门(Fusobacteria)和厚壁菌门(Firmicutes)是吉富罗非鱼肠道优势菌门.筛选出的核心差异菌属是显著富集于对照组的肠弧菌属(Enterovibrio)、鲸杆菌属(Cetobacterium)和霍氏弧菌属(Grimontia),显著富集于刺五加添加组的劳森氏菌属(Lawsonia)、不动杆菌属(Acinetobacter)、假单胞菌属(Pseudomonas)和短螺旋体属(Brevinema),在吉富罗非鱼肠道内存在着一定丰度的潜在致病菌.(5)PICRUSt2功能预测表明代谢(Metabolism)在一级功能层显著富集,对照组疾病(Human diseases)代谢通路相对丰度显著高于刺五加添加组,两个处理组在二级功能层有相似的分布特征,肠道菌群的多样性功能将在代谢中发挥重要作用.综上,饲料中添加刺五加超微粉可以影响吉富罗非鱼的肠道酶活、肝脏生化指标和肠道菌群组成和功能,促进罗非鱼的健康生长.

Eriocheir sinensis is traditionally a native high-value crab that is widely distributed in eastern Asia, and the precocity is considered the bottleneck problem affecting the development of the industry. The precocious E. sinensis is defined as a crab that reaches complete sexual maturation during the first year of its lifespan rather than as normally in the second year. However, the exact regulatory mechanisms underlying the precocity are still unclear to date. This study is the first to explore the mechanism of precocity with transcriptome-metabolome association analysis between the precocious and normal sexually mature E. sinensis. Our results indicated that the phenylalanine metabolism (map00360) and neuroactive ligand-receptor interaction (map04080) pathways play an important role in the precocity in the ovary of E. sinensis. In map00360, the predicted aromatic-L-amino-acid decarboxylase and 4-hydroxyphenylpyruvate dioxygenase isoform X1 genes and the phenethylamine, phenylethyl alcohol, trans-2-hydroxycinnamate, and L-tyrosine metabolites were all down-regulated in the ovary of the precocious E. sinensis. The map04080 was the common KEGG pathway in the ovary and hepatopancreas between the precocious and normal crab. In the ovary, the predicted growth hormone secretagogue receptor type 1 gene was up-regulated, and the L-glutamate metabolite was down-regulated in the precocious E. sinensis. In the hepatopancreas, the predicted forkhead box protein I2 gene and taurine metabolite were up-regulated and the the L-glutamate metabolite was down-regulated in the precocious crab. There was no common pathway in the testis. Numerous common pathways in the hepatopancreas between male precocious and normal crab were identified. The specific amino acids, fatty acids and flavorful nucleotide (inosine monophosphate (MP), cytidine MP, adenosine MP, uridine MP, and guanosine MP) contents in the hepatopancreas and gonads further confirmed the above omics results. Our results suggest that the phenylalanine metabolism may affect the ovarian development by changing the contents of the neurotransmitter and tyrosine. The neuroactive ligand-receptor interaction pathway may affect the growth by changing the expressions of related genes and affect the umami taste of the gonads and hepatopancreas through the differences of L-glutamate metabolite in the precocious E. sinensis. The results provided valuable and novel insights on the precocious mechanism and may have a significant impact on the development of the E. sinensis aquaculture industry.

The compound known as effective microorganisms (EMs) is widely used in aquaculture to improve water quality, but how they affect the health of Chinese mitten crab (Eriocheir sinensis) is unclear, especially in terms of intestinal microbiota and serum metabolites. In this study, we fed juvenile crabs with an EM-containing diet to explore the effects of EM on the physiological status, intestinal microbiome, and metabolites of E. sinensis. The activities of alanine aminotransferase and alkaline phosphatase were significantly enhanced by EM, indicating that EM supplementation effectively enhanced the antioxidant capacity of E. sinensis. Proteobacteria, Tenericutes, Firmicutes, Bacteroidetes, and Actinobacteria were the main intestinal microbes in both the control and EM groups. Linear discriminant effect size analysis showed that Fusobacteriaceae, Desulfovibrio, and Morganella were biomarkers in the control group, and Exiguobacterium and Rhodobacteraceae were biomarkers in the EM group. Metabolomics analysis revealed that EM supplementation increased cellular energy sources and decreased protein consumption, and oxidative stress. Together, these results indicate that EM can optimize the intestinal microbiome and serum metabolites, thereby benefiting the health of E. sinensis.

A Gram-stain-negative, facultatively anaerobic, motile, curved-rod-shaped flagellated bacterium, designated DSL-7T, was isolated from the intestine of Chanodichthys dabryi in the Yangtze river, PR China. The strain grew optimally in tryptone soy broth medium at 37 °C, pH 7.0 and with 1 % (w/v) NaCl. Strain DSL-7T showed less than 96.2 % 16S rRNA gene sequence similarity to type strains of the genus Vibrio. Phylogenetic analysis based on genomes indicated that strain DSL-7T belonged to the genus Vibrio and formed a subclade with Vibrio mimicus NCTC 11435T, Vibrio metoecus OP3HT, Vibrio cholerae ATCC 14035T, Vibrio albensis ATCC14547T, Vibrio paracholerae OP3HEDC-792T and Vibrio tarriae 2521-89T. The average nucleotide identity (ANI) and in digital DNA-DNA hybridization (dDDH) values between DSL-7T and closely related type strains were below the accepted threshold to delineate a new species of 95 and 70 %, respectively. The major cellular fatty acids were summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), C16 : 0, summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c) and C14 : 0. The genomic DNA G+C content was 47.6 mol%. Based on the phenotypic, chemotaxonomic, phylogenetic and genomic data, strain DSL-7T represents a novel species of the genus Vibrio, for which the name Vibrio chanodichtyis sp. nov. is proposed, with strain DSL-7T (=KCTC 92851T=CCTCC AB 2022396T) as the type strain.

Traditional aquaculture ponds are one of the most vulnerable ecosystems; thus, ecological aquaculture is increasingly valued for its beneficial ecological properties and ecosystem services. However, little is known about ecological aquaculture of largemouth bass with submerged vegetation. Here, we designed three ecological ponds of cultured largemouth bass with submerged macrophytes (the EM group) and three ponds with traditional aquaculture (the M group) to reveal the response of water quality, and phytoplankton and bacterial communities, to submerged macrophyte bioremediation during a 90-day culture period. We observed that Cyanobacterial outbreak occurred in the M group ponds from day 7 to the end of the experiment; however, there were no Cyanobacterial blooms in the EM group ponds throughout the culture period. Compared with the M group ponds, the EM group ponds, which had submerged hydrophytes, had significantly decreased concentrations of TP, TN, and CODMn, but significantly increased DO concentrations throughout the experimental period. Moreover, ecological aquaculture with submerged macrophytes showed strong effects on the phytoplankton and bacterial community compositions. In particular, the M group ponds had higher phytoplankton density and mainly included Cyanobacteria, whereas the EM group had lower phytoplankton density and mainly included Chlorophyta. Moreover, higher alpha diversity, as determined by Ace and Simpson index values, was detected for bacterial communities in the EM group ponds. Furthermore, PCoA clearly grouped the bacterial communities according to the two culture modes throughout the culture period. These results indicate that ecological aquaculture with submerged macrophytes can improve water quality, control Cyanobacterial blooms, and affect the diversity and composition of bacterial communities. These valuable effects seem to be beneficial and consistent to maintaining aquaculture ecosystem stability.

Chinese mitten crab (Eriocheir sinensis; H. Milne Edwards, 1853) is one of the important farmed crustaceans in China. Lipopolysaccharide (LPS), as a harmful factor, is prone to occur during the farming process of crabs. Aiming to test the hypothesis that damage degrees of the hepatopancreas in E. sinensis is correlated to LPS concentrations, in this study, E. sinensis were injected with LPS (50 μg/kg, and 500 μg/kg) and analyzed for the activity of antioxidant and immune-related enzymes, immune-related gene expression, and histopathological of hepatopancreas. As result, the hepatopancreas of E. sinensis immune-related genes, i.e., Dorsal, HSP90, Toll2, TLRs, Tube, and proPO, were significantly affected by LPS challenge. Among immune-related genes, Dorsal and proPO might play key roles in combating the LPS challenge. The activity of CAT gradually decreased with the increase of time, and the total antioxidant capacity was decreased after LPS challenge, indicating the inhibition of LPS on the antioxidant system. Interestingly, the decreasing trend of AKP and ACP activity suggested the immune system of crabs was affected by LPS challenge. The hepatopancreas section showed that the damage degree of hepatopancreas was different under the challenge of LPS with different concentrations, and the damage degree was proportional to the concentration. Our findings provide useful information for understanding the mechanism of hepatopancreas injury of E. sinensis induced by LPS infection.

Recently, the economic traits of Chinese mitten crab (Eriocheir sinensis) varieties have had a negative tendency. Meanwhile, the status of wild germplasm resources of E. sinensis is unknown, hindering the utilization of wild germplasm resources and the green development of the E. sinensis industry. Thus, the conservation of the wild E. sinensis germplasm resource is of great significance. To this end, we collected wild E. sinensis from two different river basins, the Yangtze River basin, and the Liaohe River basin, and analyzed the genetic diversity as well as the genetic differentiation in E. sinensis populations. Based on eight microsatellite markers, we found moderate genetic diversity in E. sinensis populations regardless of river basin. Based on the mitochondrial D-loop region, we found that all populations are at mutation drift equilibrium, while the Nm between any two populations is greater than 1. We hypothesized the existence of island model gene flow patterns among E. sinensis. Interestingly, genetic differentiation among E. sinensis populations was low, except that between Liaohe and Anqing or Shanghai populations. Additionally, geometric morphological analysis could distinguish E. sinensis from different basins, with an accuracy of 94.2–100%. Given the similar genetic diversity in the two basins, the genetic convergence of E. sinensis from different basins deserves further attention.

Due to the strong response to air exposure, high mortality was occurred in Coilia nasus. Previous studies reported that 10 ‰ NaCl could significantly reduce mortality in C. nasus under air exposure. To investigate the mechanisms that 10 ‰ NaCl can alleviate stress, community structure and metabolism of the intestinal flora of C. nasus were detected via metagenome and metabolome. In this study, C. nasus were divided into control group (C), air exposure group without 10 ‰ NaCl (AE), and air exposure group with 10 ‰ NaCl (AES). After air exposure stress and salinity mitigation, the mortality, intestinal microorganisms, metabolites, and physiological biomarkers were analyzed. The results showed that the mortality rate of C. nasus was reduced after salinity reduction; the antioxidant capacity was elevated compared to the AE group; and anti-inflammatory capacity was increased in the AES group compared to the AE group. Metagenomic sequencing results showed that the levels of harmful bacteria (E. coli, Aeromonas) in the Candida nasus gut increased after air exposure; beneficial bacteria (Actinobacteria, Corynebacteria) in the C. nasus gut increased after salinity reduction. Metabolomics analyses showed that AE decreased the expression of beneficial metabolites and increased the expression of harmful metabolites; AES increased beneficial metabolites and decreased harmful metabolites. Correlation analysis showed that in the AE group, beneficial metabolites were negatively correlated with oxidative stress and inflammatory response, while harmful metabolites were positively correlated with oxidative stress and inflammatory response, and were associated with bacterial communities such as Gillisia, Alkalitalia, Avipoxvirus, etc.; the correlation of metabolites with oxidative stress and inflammatory response was opposite to that of AE in the case of AES, and was associated with Lentilactobacillus, Cyanobacterium, and other bacterial communities. Air exposure caused damage to Candida rhinoceros and 10 ‰ salinity was beneficial in alleviating C. nasus stress. These results will provide new insights into methods and mechanisms to mitigate stress in fish.

为探究刀鲚(Coilia nasus)内皮素1(endothelin 1,Edn1)基因对刀鲚上颌骨长度的影响,根据此前的基因组重测序结果以及刀鲚基因组数据库,通过PCR扩增得到刀鲚Edn1基因序列,并使用直接测序法筛选并分析单核苷酸多态性(single nucleotide polymorphism,SNP)位点,分析各位点的基因型,并计算各位点的基本遗传参数、基因型频率和基因频率,将筛选出的SNP位点与刀鲚上颌骨长度性状进行关联分析、连锁不平衡分析和双倍型分析.结果表明,在刀鲚Edn1基因中共挖掘出5个SNP位点,分别为T134C、A418C、G1322A、C1607T、A1636C.G1322A与A1636C两个位点之间处于连锁不平衡状态.关联分析结果显示,T134C位点和A418C位点与上颌骨长度性状之间存在显著相关性;双倍型分析结果显示,T134C位点和A418C位点组成的双倍型中,D3(杂合TC和纯合AA)的上颌骨长度显著长于D1(纯合TT和杂合AC)和D2(纯合TT和纯合CC).此外,刀鲚开口高度/头长和上颌骨长/头长的皮尔逊相关系数r=0.41,属中等正相关.研究结果表明,T134C位点和A418C位点是刀鲚上颌骨长度的优势位点,双倍型D3为优势基因型.本研究可为刀鲚长颌骨分子标记辅助选育的候选标记提供科学依据.

There is growing evidence that long-term exposure to prometryn (a widely used herbicide) can induce toxicity in bony fish and shrimp. Our previous study demonstrated its 96 h acute toxicity on the crab Eriocheir sinensis. However, studies on whether longer exposure to prometryn with a lower dose induces toxicity in E. sinensis are scarce. Therefore, we conducted a 20 d exposure experiment to investigate its effects on the hepatopancreas and intestine of E. sinensi. Prometryn reduce the activities of antioxidant enzymes, increase the level of lipid peroxidation and cause oxidative stress. Moreover, long-term exposure resulted in immune and detoxification fatigue, while short-term exposure to prometryn could upregulate the expression of genes related to immunity, inflammation and detoxification. Prometryn altered the morphological structure of the hepatopancreas (swollen lumen) and intestine (shorter intestinal villi, thinner muscle layer and thicker peritrophic membrane). In addition, prometryn changed the species composition of the intestinal flora. In particular, Bacteroidota and Proteobacteria showed a dose-dependent decrease accompanied by a dose-dependent increase in Firmicutes at the phylum level. At the genus level, all exposure groups significantly increased the abundance of Zoogloea and a Firmicutes bacterium ZOR0006, but decreased Shewanella abundance. Interestingly, Pearson correlation analysis indicated a potential association between differential flora and hepatopancreatic disorder. Phenotypic abundance analysis indicated that changes in the gut flora decreased the intestinal organ's resistance to stress and increased the potential for opportunistic infection. In summary, our research provides new insights into the prevention and defense strategies in response to external adverse environments and contributes to the sustainable development of E. sinensis culture.