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At least 19 recordsLinked to original sources

PubMed2003

[On the chitin digestive bacteria from larval gut of Eriocheir sinensis].

The foregut, mid-gut and hind gut of Eriocheir sinensis from the first Zoea to Megalopa were dissected under asepsis condition. Bacteria were separated by plate culture after liquid medium culture. A chitin digestive bacterium was separated from the first Zoea foregut. The chitin digestive bacteria weren't founded in the same experiment from the second Zoea to Megalopa. The chitin digestive bacteria showed roundness, protuberance, glassy humid, margin regular, milk-yellow, aerotolerant anaerobe, and growing intently surrounding the chitin on the plate culture medium. The chitin could promote the growth rate of some digestive bacteria in larval gut of the crab.

Animals↗

PubMed2001

Ionic balance in the freshwater-adapted Chinese crab, Eriocheir sinensis.

Ionic regulation by the gills of the freshwater-adapted Chinese crab, Eriocheir sinensis, was examined. The balance of uptake and loss of NaCl in crabs living in freshwater was established. Urine production was measured directly by cannulating the nephropores. Daily urinary loss of Na+ is equivalent to 16% of the haemolymph Na+ content and is substantially higher than that based on data from indirect measurements reported in the literature. Weight and area of anterior and posterior gills are proportional to body weight. The role of the gills in compensating urinary loss by uptake was determined by analysing changes in Na+ and Cl- concentrations in the external medium in which isolated perfused gills were suspended. In posterior gills, salt loss is quantitatively balanced by NaCl net uptake from an external concentration of 1.3 mmol l(-1) NaCl upwards. The transport constant (Kt) for half maximum saturation of net uptake and saturation of NaCl uptake are 1.5 mmol l(-1) and 4 mmol l(-1), respectively. In contrast to previous studies in which tracer fluxes or transepithelial short-circuit currents were determined, our method of direct ion determination shows that no net uptake of Na+ or Cl- occurs in posterior gills in the absence of the respective counter ion, or when uptake of one ion is blocked by a specific inhibitor. Net uptake of Na+ and Cl- was about equal. We conclude that the uptake of the two ions is coupled. The properties of the branchial ion uptake of E. sinensis correlates with the distribution of this crab in river systems.

Adaptation, Physiological↗

PubMed2005

Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA.

Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators.

Analysis of Variance↗

PubMed2000

High pressure and glycolytic flux in the freshwater Chinese crab, Eriocheir sinensis.

The hexose part of glycolysis has been studied in the freshwater Chinese crab Eriocheir sinensis exposed to high pressure (101 ATA, i.e. 1000 m depth) at 14 degrees C and in normoxic conditions. Glycolytic fluxes (from glucose, JA and from Glucose 6 Phosphate, JB) have been determined using NADH depletion during the conversion of dihydroxy acetone phosphate into alpha-glycerol phosphate. Measurements have been performed at 14 and 19 degrees C. Pressure exposure induces an increase of glycolytic flux and a decrease of the time needed for the transition from aerobic to anaerobic glycolysis. As a consequence pressure-exposed crabs have a higher potential to increase glycolytic flux than control animals at atmospheric pressure. It is concluded that high pressure known to alter numerous enzymes individually, can also modify an overall metabolic pathway.

Analysis of Variance↗

PubMed2004

A spiroplasma associated with tremor disease in the Chinese mitten crab (Eriocheir sinensis).

An epidemic of tremor disease has been a serious problem in Chinese mitten crabs, Eriocheir sinensis, in China in recent years. The disease-causing agent was previously considered to be a rickettsia-like organism. Here, analysis of the 16S rRNA gene sequence, light and electron microscopy and cultivation in vitro were used to identify the agent. Sequence analysis of the 16S rRNA gene found it to have 98 % identity with that of Spiroplasma mirum. The agent was able to be passed through membrane filters with pores 220 nm in diameter and could be cultivated by inoculating the yolk sac of embryonated chicken eggs and M1D medium. Rotary motion and flexional movement were seen by light microscopy, and electron microscopy showed that the organism had a helical morphology and lacked a cell wall. The organism produced small colonies with a diameter of 40-50 microm after 17-25 days of incubation on solid M1D medium. The agent was found in blood cells, muscles, nerves and connective tissues of crabs inoculated with a filtrate of yolk sacs or with cultures grown in M1D medium, and it was similar in structure to those grown in eggs and cultivation broth. Disease was reproduced by experimental infection with the cultivated organisms. This study has demonstrated that the causative agent of tremor disease in the Chinese mitten crab is a member of the genus Spiroplasma. This is believed to be the first time a spiroplasma has been found in a crustacean. These findings are not only significant for studies on pathogenic spiroplasmas, but also have implications for studies of freshwater ecology.

Animals↗

PubMed2004

Purification and characterization of a new reovirus from the Chinese mitten crab, Eriocheir sinensis.

A new reovirus was recently isolated from a freshwater crab, the Chinese mitten crab, Eriocheir sinensis, in China. The complete viral particles are 55 nm in diameter, icosahedral, non-enveloped and have a mean buoyant density of 1.39 g cm(-3) in CsCl gradient. The viral genome is composed of 12 pieces of dsRNA with an electrophoretic pattern of 3/4/2/3. This virus infects connective tissue of the gills, gut and hepatopancreas. Partial cDNA cloning and sequence analysis showed that the RNA-dependent RNA polymerase is located in the first RNA segment. From its biochemical, ultrastructural and physicochemical properties, this virus is quite different from the genus Aquareovirus (Reoviridae). It may represent a new genus of Reoviridae, different from the other crab reoviruses, P and W(2).

Amino Acid Sequence↗

PubMed2026

Genome-wide epigenomic atlas and multi-omics responses of Eriocheir sinensis to natural extreme heat.

BACKGROUND: Global climate warming has led to increasingly frequent and prolonged extreme summer heat events, posing severe environmental challenges to aquaculture systems. Extreme summer heat can disrupt the performance of pond-cultured ectotherms. The Chinese mitten crab (Eriocheir sinensis) is an economically important freshwater crustacean, but coordinated molecular differences following contrasting natural summers remain incompletely characterized. RESULTS: We performed a comprehensive multi-omics analysis integrating meteorological monitoring, mRNA/lncRNA transcriptomics, small-RNA profiling of miRNAs, DNA methylomics, and LC-MS metabolomics in E. sinensis populations collected from Yancheng, China, between 2020 and 2024. Across the ten farms, survival was significantly lower in 2024, whereas yield and the proportion of large individuals showed nonsignificant downward trends. Gene-set analyses showed negative enrichment of cellular heat-response, protein-folding, oxidative-phosphorylation, and mitochondrial ATP-production terms in the 2024 cohort at the time of sampling. The integrated transcript annotation contained 72,240 lncRNAs and 63,833 mRNAs, and CpG was the predominant methylation context. Differential methylation analysis identified 73 regions and 185 cytosines, with hypomethylated events predominating within the significant subset. Metabolomic profiles differed between annual cohorts and mapped to carbohydrate, lipid, and amino-acid pathways. Cross-omics integration prioritized eight candidate genes-ADCY9, UNC79, UBN1, IFT52, ACO2, LOC126986070, LOC127001126, and LOC126997895-and qPCR reproduced the reported directions of expression for selected RNAs. CONCLUSION: This study provides the first integrative multi-omics framework for understanding chronic heat adaptation in E. sinensis. By linking transcriptomic, epigenomic, and metabolic remodeling, we elucidate the molecular mechanisms underlying energy imbalance, epigenetic reprogramming, and immune dysregulation during prolonged thermal stress. These findings offer valuable insights and genomic resources for breeding heat-tolerant crab strains and improving aquaculture resilience under ongoing climate change.

DNA methylation↗

PubMed1996

Active and electrogenic absorption of Na + and Cl- across posterior gills of Eriocheir sinensis: influence of short-term osmotic variations

Split lamellae of posterior gills of Chinese crabs (Eriocheir sinensis) acclimated to fresh water were mounted in a modified Ussing-type chamber, and the transepithelial short-circuit current and conductance were measured. The epithelium shows independent active and electrogenic absorption mechanisms for Na+ and Cl- that can be measured as positive and negative short-circuit currents, respectively, in the absence of the counter ion. Increasing the osmolarity of the haemolymph-side saline by addition of sucrose resulted in a marked decrease in active uptake of both Na+ and Cl-. In contrast, increasing the internal osmolarity by addition of urea or moderately decreasing the haemolymph-side osmolarity resulted in a marked increase in Na+ as well as Cl- transport. Circuit analysis revealed that Na+ current changes are mostly due to alterations in the apical amiloride-sensitive Na+ conductance, while Cl- current changes are caused not only by alterations in the transcellular conductance but also by changes in the electromotive force for Cl- absorption. Osmotic perturbations in the external bath induced current changes in the same directions, but the magnitudes of the effects were smaller than those after internal osmotic variations, indicating that the external barrier has a lower water permeability than the internal barrier. Short-term osmotic perturbations did not significantly affect the leak conductance, which is not associated with active transport and which may mostly reflect the paracellular conductance.

Journal Article↗

PubMed2006

Ultrastructural study on a novel microsporidian, Endoreticulatus eriocheir sp. nov. (Microsporidia, Encephalitozoonidae), parasite of Chinese mitten crab, Eriocheir sinensis (Crustacea, Decapoda).

A microsporidian pathogen, infecting the epithelial cells of the hepatopancreas of Chinese mitten crab, Eriocheir sinensis, was studied by electron microscopy. The detailed ultrastructure of life cycle of the pathogen including proliferative and sporogonic developmental stages are provided. All stages of the parasite are haplokaryotic and develop in a vacuole bounded by a single membrane in contact with host cell cytoplasm. Sporogenesis is synchronous with the same developmental stage in one vacuole. Sporogony shows a characteristic of multinucleate sporogonial plasmodia divided by rosette-like division, producing 4 or 8 sporoblasts. The mature spore is ellipsoidal, length (mean) 1.7 microm, width 1.0 microm, with a uninucleate in the center of the sporoplasm, 7 turns of the polar filament, a bell-like polaroplast of compact membranes and obliquely positioned posterior vacuole. The morphological characteristics of this novel microsporidian pathogen have led us to assign the parasite to a new species of Endoreticulatus, E. eriocheir sp. nov., that has not been reported previously from crab.

Animals↗

PubMed2000

Active NaCl absorption across split lamellae of posterior gills of the chinese crab Eriocheir sinensis: stimulation by eyestalk extract.

Split lamellae of the posterior gills of freshwater-adapted Chinese crabs (Eriocheir sinensis) were mounted in a modified Ussing-type chamber, and active and electrogenic absorption of Na(+) and Cl(-) were measured as positive (I(Na)) or negative (I(Cl)) short-circuit currents. Haemolymph-side addition of eyestalk extract stimulated I(Cl) by increasing both the transcellular Cl(-) conductance and the electromotive force for Cl(-) absorption. The effect was dose-dependent. Boiling the eyestalk extract did not change its effectiveness. The stimulating factor passed through dialysis tubing, indicating that it has a molecular mass of less than 2 kDa. R(p)cAMPS, a blocker of protein kinase A, reduced the stimulated I(Cl). Eyestalk extract stimulated I(Na) by increasing the transcellular Na(+) conductance at constant electromotive force. Amiloride-induced current-noise analysis revealed that stimulation of I(Na) was accompanied by an increase in the apparent number of open apical Na(+) channels at a slightly reduced single-channel current. In addition to the electrophysiological experiments, whole gills were perfused in the presence and in the absence of putative transport stimulators, and the specific activities of the V-ATPase and the Na(+)/K(+)-ATPase were measured. Eyestalk extract, theophylline or dibutyryl-cyclic AMP stimulated the activity of the V-ATPase, whereas the activity of the Na(+)/K(+)-ATPase was unaffected. The simultaneous presence of R(p)cAMPS prevented the stimulation of V-ATPase by eyestalk extract or theophylline.

Absorption↗

PubMed2002

Rickettsia-like organism associated with tremor disease and mortality of the Chinese mitten crab Eriocheir sinensis.

We report the discovery of a rickettsia-like organism (RLO) in cultured freshwater Chinese mitten crab Eriocheir sinensis. The RLO caused tremor disease and was apparently responsible for a mass mortality (30 to 90%) in 2 provinces in southeast China. Moribund crabs were investigated from different districts during outbreaks in 1999 and 2000. With electron microscopy, 3 different pathogens were detected in moribund crabs: a rickettsia-like organism (RLO), virus-like particles (VLP) and a microsporidian-like protozoan (MLP). Based on the high prevalence, infection intensity and cytopathological signs, the RLO was considered to be the probable cause of the high mortality. Both VLP and MLP occurred at low prevalences and were considered secondary infections. The RLO was 0.22 to 0.35 microm in diameter, granular or clavate, bounded by a cell wall and membrane, and possessed no nucleus but a nucleoid was present. When dividing, RLOs occurred in irregular shapes, such as dumbbells, awls, and crescents. The RLOs exhibited a predilection for muscle and connective tissues and were probably transported to various tissues and organs by hemocytes.

Animals↗

PubMed1992

Acid-base changes on transfer between sea- and freshwater in the Chinese crab, Eriocheir sinensis.

The time course of changes in hemolymph pH, PCO2 and bicarbonate concentration were followed in euryhaline Chinese crabs, Eriocheir sinensis, after transfer from seawater (SW) to freshwater (FW) and vice versa. In order to correlate these changes with the animal's ionic status, hemolymph osmolarity and Na+ and Cl- concentrations as well as net exchanges of acid-base equivalents with the external water were also measured. Transfer from SW to FW induced a metabolic alkalosis which peaked after 3 days and declined thereafter but remained significant by 29 days. Hemolymph PCO2 was markedly elevated in FW, thus moderating the increase in hemolymph pH. Osmolarity and Na+ and Cl- concentrations reached a new steady state at lowered values by 24-48 h and a significant outflux of acidic equivalents was measured only during the first 2 days. Transfer from FW to SW conversely induced a metabolic acidosis which was almost fully compensated by a marked hypocapnia. It is concluded that external acid-base exchanges coupled to ionic readjustments following a salinity transition cannot solely explain the associated acid-base disturbances, the metabolic component of which must also rely on tissular processes probably linked to cell volume regulation.

Acid-Base Equilibrium↗

PubMed2004

Purification of vitellin from the ovary of Chinese mitten-handed crab (Eriocheir sinensis) and development of an antivitellin ELISA.

Vitellin was purified from ovaries of mature female Chinese mitten-handed crab (Eriocheir sinensis) using gel filtration chromatography. Analysis by native PAGE showed the vitellin had a native molecular mass of 520 kDa, while denaturing SDS-PAGE revealed two subunits of 97 and 74 kDa. Purified vitellin was used to raise polyclonal antisera, with which an enzyme-linked immunosorbent assay (ELISA) was developed. The ELISA was sensitive and could effectively detect vitellin in the range of 7.8-500 ng. Furthermore, vitellin levels in various developmental stages of oogenesis were measured with the ELISA assay. The results indicated that levels of vitellin increased significantly from 0.22 mg/ovary at Stage II to 360.31 mg/ovary at Stage IV.

Animals↗

PubMed2004

Uptake of cadmium through isolated perfused gills of the Chinese mitten crab, Eriocheir sinensis.

Using the perfusion method, we compared cadmium accumulation and influx across the gills of the euryhaline Chinese mitten crab Eriocheir sinensis, exposed to 4.8 microM cadmium in the incubation medium (OUT). Cadmium influx was not observed across posterior gills while it ranged from 0.15 to 6.82 nmol Cd g(-1) gill w.w. h(-1) across anterior ones. For these respiratory gills, a strong increase (40 times) was observed when calcium was removed in both incubation and perfusion media while the lack of sodium in the perfusion medium resulted in a 46 times decrease. For crabs acclimated 15 days to artificial seawater, cadmium influx across anterior gills showed a 21 times decrease when compared with freshwater acclimated ones. On the other hand, after 3 h of perfusion, we detected cadmium accumulation in both types of gills, ranging from 3.8 to 68 nmol Cd g(-1) gill w.w. in anterior gills and from 2.1 to 39 nmol Cd g(-1) gill w.w. in posterior ones. Such accumulations represent between 61.3 and 100% of the total uptake of cadmium through the gills. From these results, we suggest that cadmium can penetrate more easily into the hemolymph space through the 'respiratory' type epithelium present in the anterior gills but absent in the posterior ones. This metal uptake is likely to occur at least in part through the same pathways as calcium. On the contrary, cadmium seems to be sequestered inside the posterior gills, perhaps in the cuticle of the salt-transporting type epithelium.

Animals↗

PubMed2006

The site of vitellogenin synthesis in Chinese mitten-handed crab Eriocheir sinensis.

The objective of this study was to investigate the synthesis site of vitellogenin in the Chinese mitten-handed crab, Eriocheir sinensis. Using the RT-PCR techniques, the cDNA fragments isolated from the ovaries of vitellogenic female crab, we found that its deduced amino acid sequence had a high identity with that from other decapods crustacean vitellogenin. This cDNA fragments were used as probes to examine the transcription of mRNAs encoding the Vg. The mRNA expression was observed in vitellogenic female hepatopancreas, which was not detected in any other tissues including muscle, heart, and subepidermal tissues. The positive immunocytological staining with antibody against vitellin were found in ovaries and hepatopancreas of vitellogenic female, which was determined by immunological and immunohistochemical techniques. These results suggest that both ovaries and hepatopancreas are capable of synthesizing vitellogenin. Therefore, it was concluded that hepatopancreas is the extraovarian site of vitellogenin synthesis in E. sinensis.

Animals↗

PubMed2002

[Starvation metabolism in parent Chinese mitten-handed crab (Eriocheir sinensis)].

The experiment was conducted to study the influence of starvation on the metabolism of parent Chinese mitten-handed crab (Eriocheir sinensis) with weights of 54.59 (+/- 2.37) g under 20 (+/- 0.5) degree C during Oct. to Dec., 1998. The results showed oxygen consumption, CO2 production and ammonia-N excretion of the parent crab being starved for 30 days were 50.0%, 63.4%, and 59.1% of those of the fed crab, respectively. The course of oxygen consumption reduction could be divided into four phases: 1) from the 1st day to the 6th day, the metabolic rate decreased remarkably; 2) from the 7th day to the 15th day, the metabolic rate kept relatively stable; 3) from the 16th day to the 25th day, the metabolic rate decreased markedly again; and 4) from 26th day to 30th day (the end time of the experiment), the metabolic rate decreased most dramatically. There were only three phases during the course of CO2 production and ammonia-N excretion reduction. Meanwhile, the standard metabolism of the starved crab reduced from 4.45 to 2.36 J.g-1.h-1, and lipid was used as the first energy source in the course of starvation.

Ammonia↗

PubMed2001

Variation in lipid composition of Chinese mitten-handed crab, Eriocheir sinensis during ovarian maturation.

This experiment was conducted to investigate the variation in lipid composition during the ovarian maturation of the crab Eriocheir sinensis. The Chinese mitten-handed crab broodstock was divided into six different maturation periods according to the size and color of ovary. Ovary, hepatopancreas, muscle, and hemolymph of broodstock in different maturation periods were analyzed for total lipid and fatty acids using gas chromatography, and lipid classes by thin-layer chromatography. The ovarian lipid concentration (expressed as percent wet ovarian weight) increased steadily from stage II (5.4%) to stage IV (19.1%), and decreased to the lowest levels after spawning (stage V, 6.6%). The hepatopancreatic lipid concentration (expressed as percent wet hepatopancreatic weight) increased with maturity of the ovaries, reached a maximum at stage III(2) (29.9%), and decreased during the subsequent period to spawning (16.7%). The muscular and hemolymph lipid concentration did not change markedly during the ovarian development. These results suggest the possible movement of hepatopancreatic lipids to the ovaries during the ovarian maturation. Both triacylglycerol and phosphatidylcholine were responsible for the increase in ovarian lipid concentration during sexual maturation. The fatty acids of total lipid, triacylglycerol, and phosphatidylcholine of the ovaries did not vary systematically during the ovarian maturation, but the ratio between n-3PUFA (polyunsaturated fatty acid) and n-6PUFA did change regularly with the ovarian lipid. These suggest that enough PUFA, especially n-3PUFA, should be supplied to the crab during ovarian maturation.

Animals↗

PubMed2005

Differential protein expression profiles in anterior gills of Eriocheir sinensis during acclimation to cadmium.

Using a proteomic approach, we characterized different protein expression profiles in anterior gills of the Chinese mitten crab, Eriocheir sinensis, after cadmium (Cd) exposure. Two experimental conditions were tested: (i) an acute exposure (i.e. 500 microg Cd l(-1) for 3 days) for which physiological, biochemical and ultrastructural damage have been observed previously; (ii) a chronic exposure (i.e. 50 microg Cd l(-1) for 30 days) resulting in physiological acclimation, i.e. increased resistance to a subsequent acute exposure. Two-dimensional gel electrophoresis (2-DE) revealed six protein spots differentially expressed after acute, and 31 after chronic Cd exposure. From these spots, 15 protein species were identified using MS/MS micro-sequencing and MS BLAST database searches. Alpha tubulin, glutathione S-transferase and crustacean calcium-binding protein 23 were down-regulated after an acute exposure, whereas another glutathione S-transferase isoform was up-regulated. Furthermore, analyses revealed the over-expression of protein disulfide isomerase, thioredoxin peroxidase, glutathione S-transferase, a proteasome subunit and cathepsin D after chronic exposure. Under the same condition, ATP synthase beta, alpha tubulin, arginine kinase, glyceraldehyde-3-phosphate dehydrogenase and malate dehydrogenase were down-regulated. These results demonstrate that acute and chronic exposure to waterborne Cd induced different responses at the protein expression level. Protein identification supports the idea that Cd mainly exerts its toxicity through oxidative stress induction and sulfhydryl-group binding. As a result, analyses showed the up-regulation of several antioxidant enzymes and chaperonins during acclimation process. The gill proteolytic capacity seems also to be increased. On the other hand, the clearly decreased abundance of several enzymes involved in energy transfer suggests that chronic metal exposure induced an important metabolic reshuffling.

Acclimatization↗