Search Results (25)

“Milky disease” of the Chinese mitten crab (Eriocheir sinensis), caused by Metschnikowia bicuspidata, leads to substantial economic losses. Despite extensive research on its pathogenesis, the genetic basis of host resistance and underlying regulatory mechanisms remain unclear, limiting the development of disease-resistant varieties. This study aimed to (1) evaluate resistance differences among 10 E. sinensis families (five highly resistant and five sensitive) via artificial challenge; (2) identify disease-resistance-associated genetic loci using genome-wide association analysis (GWAS). Our findings revealed that the F05 family exhibited the strongest resistance, with a mortality rate of only 3% and a molting rate of 73%, accompanied by superior growth performance. Whole-genome resequencing identified 10,161,545 high-quality SNPs, and GWAS detected 767 loci significantly associated with disease-resistance traits, among which two pleiotropic SNPs (Chr46:18395778 and Chr1:20680490) were simultaneously associated with both “dead or not” and “qPCR fixed amount of fungi”, reflecting their functional relevance in regulating survival and pathogen load. Notably, we propose for the first time that E. sinensis achieves resistance by inducing M. bicuspidata into a viable but nonculturable (VBNC) state, in which the fungal cells remain metabolically active but cannot form colonies on conventional culture media. This study establishes a multidimensional resistance evaluation system, clarifies the genetic basis and novel mechanism of resistance, and provides valuable molecular markers for marker-assisted breeding. The findings contribute to reducing disease-related losses and promoting sustainable development of the E. sinensis aquaculture industry. Full article

The Chinese mitten crab (Eriocheir sinensis) from Yangcheng Lake is a globally renowned geographical indication product. To characterize changes in stable isotopic signatures in this species in Yangcheng Lake during the year-round culture period, this study investigated the dynamic changes in stable isotopic fingerprints (δ¹³C, δ¹⁵N, δ²H and δ¹⁸O) of the third pereiopod across an annual aquaculture cycle. Isotopic ratios were analyzed via one-way ANOVA, principal component analysis (PCA), linear discriminant analysis (LDA) and Pearson correlation analysis. Results demonstrated that δ¹³C stabilized after six months of cultivation, showing no significant temporal variation (p > 0.05). Multivariate statistical analysis further revealed that the samples cultured in the initial period could be clearly differentiated in both PCA and LDA plots. However, after six months, the monthly sample points became highly overlapping and indistinguishable, indicating that the crabs had developed stable and consistent isotopic “fingerprints” by that time. Pearson correlation analysis indicated significant correlations among all other isotope pairs, with the exception of δ¹⁵N and δ²H. This study confirms that isotopic signatures require prolonged cultivation (≥6 months) to reflect authentic geographical traits. In addition, our findings provide a basis for verifying the origin of Chinese mitten crab and other aquatic taxa in Yangcheng Lake. Full article

This study investigated the influence of two distinct aquaculture systems, namely, the wheat-crab model (WCM) and pond culture (PC) model, on the growth, physiological well-being, and gut microbial structure of Chinese mitten crabs (Eriocheir sinensis). A total of 120 adult crabs were randomly selected from the two systems: 60 crabs from the WCM, including 30 females and 30 males, and 60 crabs from the PC model, also including 30 females and 30 males. The gonadosomatic index of female crabs in the WCM was notably higher than that of the other groups, while the hepatopancreatic index was significantly lower. Significant variations were not observed in final weight, fullness, or muscle yield between the WCM and PC groups. Biochemical evaluations indicated no substantial differences in antioxidant capabilities between the two systems; however, female crabs demonstrated increased critical antioxidant enzyme activity, such as for catalase and superoxide dismutase, and significantly elevated cholesterol levels. Additionally, the expression of the genes IL, ProPO, and Keap1 was significantly higher in the WCM group than the PC group, whereas the expression of ALF2, Myd88, and CncC did not significantly differ between the two cultivation methods. Non-targeted metabolomics analysis revealed notable distinctions in metabolite profiles between the two systems. Moreover, the WCM facilitated an increase in beneficial Firmicutes bacteria while reducing potentially harmful microorganisms, suggesting improved immune function in crabs raised under the WCM. In summary, female crabs reared in the WCM matured earlier and exhibited slightly better health conditions compared to those grown in the PC model. Full article

Metschnikowia bicuspidata is the specific pathogen for “milky disease” in the Chinese mitten crab (Eriocheir sinensis), accounting for huge losses to the industry. And yet, there is no precise study describing the pathogenesis of M. bicuspidata, largely hindering the development of novel control methods against its causing diseases. Here, we compared the transcriptomes of M. bicuspidata cells collected from a control group (cultured without E. sinensis hemocytes) and a treatment group (cultured with E. sinensis hemocytes), using RNA sequencing. Through comprehensively analyzing the differentially expressed genes (DEGs), both the most regulated ones and the ones involved in crucial enriched KEGG pathways, we found that certain processes might be required for M. bicuspidata’s survival under hemocyte stress. Key genes involved in oxidative phosphorylation, fatty acid metabolism, upper glycolysis, and gluconeogenesis were upregulated, and those for β-glucan unmasking, autophagy, and cell polarity were downregulated, in the treatment group. Our results suggest that M. bicuspidata colonizes and therefore establishes an infection in E. sinensis via enhancing aerobic respiration, glucose-6-phosphate accumulation, and cell-wall masking. In addition, we applied multiple means to evaluate a series of candidate reference genes and found that PMA1 in combination with ACT1 is the most suitable choice for accurate normalization in quantitative real-time PCR (qRT-PCR) assays. Thus, we used this combination as the reference and performed qRT-PCR verification of several DEGs. It is shown that the expression trends of these tested DEGs in qRT-PCR assays are the same as those in RNA-Seq assays. This study not only provides insights into strategies facilitating M. bicuspidata’s survival within E. sinensis, initially elucidating the pathogenesis of this yeast, but also recommends a useful molecular tool regarding qRT-PCR assays in this pathogen. Full article

The Chinese mitten crab (Eriocheir sinensis) is an economically important crustacean. With the development of the E. sisnensis industry, precocity has become a significant challenge in juvenile crab culturing. In this study, the eyestalks of female E. sinensis from precocious (PE) and normal juvenile (NE) groups were used for proteome and metabolome analyses. In total, 731 up-regulated and 657 down-regulated differentially expressed proteins (DEPs) were identified in the PE and NE groups. In addition, 110 differentially expressed metabolites (DMs) were up-regulated and 256 were down-regulated in the PE group. An integrated analysis showed 5667 significant correlations between the metabolites and proteins and 109 common pathways in the proteome and metabolome. The proteins were mostly associated with the mechanistic target of rapamycin (mTOR) pathway, longevity regulation, autophagy, and the pyrimidine and purine metabolism pathways. The metabolites were primarily enriched in amino acid and lipid metabolisms. These results demonstrated the differences in the PE and NE groups at two omics levels and will be useful for the E. sinensis industry. Full article

The cultivation of the Chinese mitten crab (Eriocheir sinensis) is an important component of China’s aquaculture industry and also a field of concern worldwide. It focuses on the selection of high-quality, disease-free juvenile crabs. However, the early maturity rate of more than 18.2% and the mortality rate of more than 60% make it difficult to select suitable juveniles for adult culture. The juveniles exhibit subtle distinguishing features, and the methods for differentiating between sexes vary significantly; without training from professional breeders, it is challenging for laypersons to identify and select the appropriate juveniles. Therefore, we propose a task-aligned detection algorithm for identifying one-year-old precocious Chinese mitten crabs, named R-TNET. Initially, the required images were obtained by capturing key frames, and then they were annotated and preprocessed by professionals to build a training dataset. Subsequently, the ResNeXt network was selected as the backbone feature extraction network, with Convolutional Block Attention Modules (CBAMs) and a Deformable Convolution Network (DCN) embedded in its residual blocks to enhance its capability to extract complex features. Adaptive spatial feature fusion (ASFF) was then integrated into the feature fusion network to preserve the detailed features of small targets such as one-year-old precocious Chinese mitten crab juveniles. Finally, based on the detection head proposed by task-aligned one-stage object detection, the parameters of its anchor alignment metric were adjusted to detect, locate, and classify the crab juveniles. The experimental results showed that this method achieves a mean average precision (mAP) of 88.78% and an F1-score of 97.89%. This exceeded the best-performing mainstream object detection algorithm, YOLOv7, by 4.17% in mAP and 1.77% in the F1-score. Ultimately, in practical application scenarios, the algorithm effectively identified one-year-old precocious Chinese mitten crabs, providing technical support for the automated selection of high-quality crab juveniles in the cultivation process, thereby promoting the rapid development of aquaculture and agricultural intelligence in China. Full article

Pond culture is the primary method for cultivating Chinese mitten crab (Eriocheir sinensis), with phytoplankton significantly influencing their growth. Green algae benefit crab growth by serving as supplementary food, while cyanobacteria, particularly during blooms, hinder it and pose health risks. Environmental changes in nutrient levels, temperature, and light significantly affect phytoplankton communities in ponds, impacting both ecosystem stability and crab growth. However, there is a limited understanding regarding the patterns of phytoplankton changes within adult Chinese mitten crab culture ponds. This study conducted monthly collection and analysis of phytoplankton throughout the culture cycle in typical adult Chinese mitten crab culture ponds, concurrently measuring physical and chemical water parameters to explore the correlation between phytoplankton changes and environmental factors. The results revealed distinct seasonal variations in phytoplankton composition. Chlorophyta and Bacillariophyta, such as Chlorella, Pediastrum, and Cocconeis, predominated in spring, while Chlorophyta and cyanobacteria, such as Volvox, Anabaena, and Microcystis, dominated in summer, and cyanobacteria and Bacillariophyta, such as Microcystis, Dolichospermum, and Cocconeis, prevailed in autumn. Total phytoplankton density consistently increased throughout the culture period. Microcystis constituted the majority of cyanobacteria biomass throughout most months. Although the total phytoplankton biomass fluctuated, cyanobacteria biomass consistently rose each month, reaching a peak of 61.7 mg/L in October. Water temperature and pH emerged as the primary environmental drivers influencing changes in phytoplankton community structure. Cyanobacteria density reached its peak between 18 and 26 °C and at a pH range of 7.5–8.5. These findings highlight the need for environmental regulation and cyanobacteria control in Chinese mitten crab culture ponds, thus promoting the health and sustainability of the Chinese mitten crab culture. Full article

The Chinese mitten crab (CMC) also known as Eriocheir sinensis has great significance in the aquaculture industry. The bacterial communities inhabiting the CMC’s gut may differ depending on the host habitat and can aid in their normal biological functioning. These microbes are also known to have certain effects on their flavor. In this study, we utilized MiSeq high-throughput sequencing technology to explore the diversity of bacterial communities in the gut of CMCs from three different geographical locations in Korea: the Geum (GD), Han (HD), and Tamjin (TD) rivers. Although most of the environmental parameters were similar at the three sites, significant differences in conductivity (CDS), dissolved oxygen (DO), and salinity were observed. The results show that CMCs sampled from these locations exhibited distinct microbial composition and abundance. For example, the genus Candidatus Hepatoplasma displayed significantly higher abundance in CMCs from HD than those in the other locations, suggesting nutritional stress. Similarly, the crabs collected from TD showed a higher abundance of pathogenic Helicobacter than those from HD and GD sites. We also observed differences in the amino acid, nucleotide, and lactic acid concentrations between different tissues such as the muscle, hepatopancreas, and testis of CMCs. However, only small differences were observed when these characteristics were compared in CMCs from different locations. Our results offer important insights into the intestinal bacterial composition in CMCs which in turn may help in designing better culturing strategies for these important species of crabs. Full article

This study evaluated the disparities in growth performance and nutritional composition between two common Chinese mitten crab varieties, “Jianghai 21” and “Changjiang 2”, cultured in Jiangxi Province. Over the breeding period, parameters such as body weight, height, carapace length and width, and lengths of the second and third legs exhibited increases. Growth indices of “Jianghai 21” surpassed those of “Changjiang 2” during the intermediate and late breeding phases. While “Changjiang 2” demonstrated significantly higher crude lipid content than “Jianghai 21”, the latter exhibited markedly higher levels of total amino acids (TAAs), essential amino acids (EAAs), and delectable amino acids. Although overall nutrient composition did not significantly differ, TAA and EAA contents in the hepatopancreas were notably greater in “Jianghai 21” than in “Changjiang 2”. Moreover, a total of 901 differentially expressed genes (DEGs) were identified between the two varieties, with 560 upregulated and 341 downregulated. These DEGs were primarily associated with pathways related to fatty acid degradation, metabolism, and growth regulation. The observed variances in growth performance and nutrient composition between “Jianghai 21” and “Changjiang 2” suggest potential regulation by relevant genes. In summary, the results showed that the growth performance of “Jianghai 21” is greater than that of “Changjiang 2”, offering valuable insights for the selection of aquaculture varieties in the region. Full article

To confirm whether Chinese mitten crabs (Eriocheir sinensis), commonly known as hairy crabs or river crabs, in non-Yangcheng Lake areas undergo morphological convergence with the original crabs in the Yangcheng Lake purse seine and high-standard modified aquaculture ponds after being “introduced” or “bathed”-cultured, we employed a geometric morphometrics approach. This approach allowed us to compare and analyze the dynamic changes in the carapace morphology of both the original and “introduced” crabs in Yangcheng Lake and high-standard ponds in Kunshan City at 0, 7, 14, and 30 days after “bathing” culture. The geometric morphological analysis of the carapace was conducted using a system of 35 established landmarks. The stepwise discriminant analysis of the relative distortion score revealed morphological differences between “introduced” and resident original crabs in the Yangcheng Lake area and in high-standard modified ponds after 7, 14, and 30 days of bathing culture. The accuracy of the discriminant analysis was 100%. The results of the geometric morphological visualization demonstrated that the carapaces of the bathed crabs underwent adaptive changes in the water. However, even after one month of bathing culture, the “introduced” crabs in lakes and ponds could not reach the morphological characteristics of the original crabs, i.e., their carapaces did not exhibit the characteristics of the original crabs. Full article

M. bicuspidata var. bicuspidata is a pathogenic yeast which can affect aquacultured and marine-cultured animals such as brine shrimp, ridgetail white prawn, chinook salmon, giant freshwater prawn, the Chinese mitten crab, marine crab, the mud crab, the mangrove land crab, the Chinese grass shrimp, sea urchins, sea urchins, Daphnia dentifera and even snails, causing a milky disease, and it has caused big economic losses in aquacultural and marine-cultural industries in the past. However, the detailed mechanisms and the reasons for the milky disease in the diseased aquatic animals are still completely unknown. So far, only some antimycotics, killer toxins and Massoia lactone haven been found to be able to actively control and kill its growth. The ecofriendly, green and renewable killer toxins and Massoia lactone have high potential for application in controlling the milky disease. Full article

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. Full article

The interaction between nutrients, heavy metals, and sediment bacterial communities play a key role in the health of crabs and the biogeochemical cycles of aquaculture systems. However, the effects of sediment improvement activities in crab culture on nutrients and heavy metals and the response of bacterial communities to the relevant changes are unclear. In this study, 24 water and sediment samples were collected from two aquaculture sites (total of 12 ponds, 6 at each site). High-throughput sequencing was used to determine the structure of the bacterial community and the diversity in water and sediment samples. The relationship between nutrients, heavy metals, and bacterial communities and the changes of the three before and after the improvement of the sediment were analyzed. The results showed that Proteobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, and Firmicutes were predominant at the phylum level of sediment. Sediment improvement has an effect on NH₄⁺-N, sulfide, total organic carbon (TOC), and heavy metals in sediments to varying degrees. In addition, redundancy analysis found that NH₄⁺-N, NO₃⁻-N, TP, and heavy metals were key drivers in crab culture pond sediments. The results of functional prediction showed that carbon, nitrogen, and sulfur metabolism were the dominant processes in the two crab farming areas. Overall, changes in nutrients and heavy metals caused by sediment improvement further affected the structure and function of bacterial communities and may affect biogeochemical cycles. Our study has deepened the understanding of the effects of sediment improvement on nutrients, heavy metals, and bacterial communities in crab culture ponds. Full article

Enrofloxacin is an important antimicrobial drug that is widely used in aquaculture. Enrofloxacin residues can have negative effects on aquatic environments and animals. The toxicological effects of different concentrations of enrofloxacin residues in cultured water on Chinese mitten crabs (Eriocheir sinensis) were compared. A histological analysis of the E. sinensis hepatopancreas demonstrated that the hepatopancreas was damaged by the different enrofloxacin residue concentrations. The hepatopancreas transcriptome results revealed that 1245 genes were upregulated and that 1298 genes were downregulated in the low-concentration enrofloxacin residue group. In the high-concentration enrofloxacin residue group, 380 genes were upregulated, and 529 genes were downregulated. The enrofloxacin residues led to differentially expressed genes related to the immune system and metabolic processes in the hepatopancreas of the Chinese mitten crab, such as the genes for alkaline phosphatase, NF-kappa B inhibitor alpha, alpha-amylase, and beta-galactosidase-like. The gene ontology terms “biological process” and “molecular function” were enriched in the carboxylic acid metabolic process, DNA replication, the synthesis of RNA primers, the transmembrane transporter activity, the hydrolase activity, and the oxidoreductase activity. A Kyoto Encyclopedia of Genes and Genomes pathway analysis determined that the immune and metabolic signal transduction pathways were significantly enriched. Furthermore, the nonspecific immune enzyme (alkaline phosphatase) and the metabolic enzyme system played a role in the enrofloxacin metabolism in the E. sinensis hepatopancreas. These findings helped us to further understand the basis of the toxicological effects of enrofloxacin residues on river crabs and provided valuable information for the better utilization of enrofloxacin in aquatic water environments. Full article

L-tryptophan (L-TRP) is an essential amino acid for the normal growth of crustaceans. As a nutritional supplement and antioxidant, L-TRP has the function of immune and antioxidant capacity regulation. From July to November, the effects of L-TRP on the immunity, antioxidant capacity and intestinal microflora of the Chinese mitten crab (Eriocheir sinensis) in pond culture were investigated. After feeding an L-TRP diet for 30 (named as August), 60 (named as September) and 106 (named as November) days, respectively, the activities of the immune and antioxidant enzymes in the hepatopancreas and hemolymph were evaluated, and the intestinal microbiota were profiled via high-throughput Illumina sequencing. The results showed that supplementation of L-TRP significantly increased the activities of AKP in the hepatopancreas in September, and significantly increased the activities of ACP in the hepatopancreas in August and September, and the hemolymph’s ACP activities also significantly increased in August and November (p < 0.05). Similarly, the activities of SOD, AOC and POD in the hepatopancreas significantly increased in September and November (p < 0.05) after feeding the L-TRP diet; meanwhile, the activities of SOD and AOC in the hemolymph also significantly increased in August (p < 0.05). However, in August, the L-TRP diet resulted in a significant increase in MDA activity in the hepatopancreas and hemolymph (p < 0.05). In addition, the results of the intestinal microbiota analysis showed that Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla in August, September and November, and Patescibacteria was the dominant phylum in September and November. After feeding the L-TRP diet, the richness of Cyanobacteria and Desulfobacterota significantly increased in August (p < 0.05), and the richness of Actinobacteriota significantly decreased in September (p < 0.05). Moreover, the L-TRP supplementation significantly reduced the abundance of ZOR0006 in the Firmicutes in September (p < 0.05). In conclusion, dietary L-TRP could improve the immunity and antioxidant ability and impact the intestinal health of E. sinensis at the early stage of pond culturing. However, long-term feeding of an L-TRP diet might have no positive impact on the activities of the immune, antioxidant enzymes and intestinal microbiota. Full article