Dataset Information

Characterization and expression of glutamate dehydrogenase in response to acute salinity stress in the Chinese mitten crab, Eriocheir sinensis.

ABSTRACT: BACKGROUND:Glutamate dehydrogenase (GDH) is a key enzyme for the synthesis and catabolism of glutamic acid, proline and alanine, which are important osmolytes in aquatic animals. However, the response of GDH gene expression to salinity alterations has not yet been determined in macro-crustacean species. METHODOLOGY/PRINCIPAL FINDINGS:GDH cDNA was isolated from Eriocheir sinensis. Then, GDH gene expression was analyzed in different tissues from normal crabs and the muscle of crabs following transfer from freshwater (control) directly to water with salinities of 16‰ and 30‰, respectively. Full-length GDH cDNA is 2,349 bp, consisting of a 76 bp 5'- untranslated region, a 1,695 bp open reading frame encoding 564 amino acids and a 578 bp 3'- untranslated region. E. sinensis GDH showed 64-90% identity with protein sequences of mammalian and crustacean species. Muscle was the dominant expression source among all tissues tested. Compared with the control, GDH expression significantly increased at 6 h in crabs transferred to 16‰ and 30‰ salinity, and GDH expression peaked at 48 h and 12 h, respectively, with levels approximately 7.9 and 8.5 fold higher than the control. The free amino acid (FAA) changes in muscle, under acute salinity stress (16‰ and 30‰ salinities), correlated with GDH expression levels. Total FAA content in the muscle, which was based on specific changes in arginine, proline, glycine, alanine, taurine, serine and glutamic acid, tended to increase in crabs following transfer to salt water. Among these, arginine, proline and alanine increased significantly during salinity acclimation and accounted for the highest proportion of total FAA. CONCLUSIONS:E. sinensis GDH is a conserved protein that serves important functions in controlling osmoregulation. We observed that higher GDH expression after ambient salinity increase led to higher FAA metabolism, especially the synthesis of glutamic acid, which increased the synthesis of proline and alanine to meet the demand of osmoregulation at hyperosmotic conditions.

SUBMITTER: Wang Y

PROVIDER: S-EPMC3355100 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Characterization and expression of glutamate dehydrogenase in response to acute salinity stress in the Chinese mitten crab, Eriocheir sinensis.

Wang Yueru Y Li Erchao E Yu Na N Wang Xiaodan X Cai Chunfang C Tang Boping B Chen Liqiao L Van Wormhoudt Alain A

PloS one 20120517 5

<h4>Background</h4>Glutamate dehydrogenase (GDH) is a key enzyme for the synthesis and catabolism of glutamic acid, proline and alanine, which are important osmolytes in aquatic animals. However, the response of GDH gene expression to salinity alterations has not yet been determined in macro-crustacean species.<h4>Methodology/principal findings</h4>GDH cDNA was isolated from Eriocheir sinensis. Then, GDH gene expression was analyzed in different tissues from normal crabs and the muscle of crabs ...[more]

PMID: 22615974

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Project description:Environmental hypoxia represents a major physiological challenge for Eriocheir sinensis and Palaemonetes sinensis and is a severe problem in aquaculture. Therefore, understanding the metabolic response mechanisms of E. sinensis and P. sinensis, which are economically important species, to environmental hypoxia and reoxygenation is essential. However, little is known about the intrinsic mechanisms by which E. sinensis and P. sinensis cope with environmental hypoxia at the metabolic level. Hypoxia-reoxygenation represents an important physiological challenge for their culture. In this study, respiratory metabolism and respiratory metabolic enzymes of E. sinensis and P. sinensis were evaluated after different hypoxia and reoxygenation times. The results showed that environmental hypoxia had a dramatic influence on the respiratory metabolism and activities of related enzymes. The oxygen consumption rates (OCR) significantly increased as hypoxia time increased, while the ammonia excretion rate (AER) was significantly lower than that in the control group after 8 h hypoxia. The oxygen to nitrogen ratio (O:N) in the control group was <16, indicating that all the energy substrates were proteins. After environmental hypoxia, the O:N significantly increased, and the energy substrate shifted from protein to a protein-lipid mixture. The OCR, AER, and O:N did not restore to initial levels after 2 h or 12 h reoxygenation and was still the same as after 8 h hypoxia. As environmental hypoxia time increased, succinate dehydrogenase (SDH) gradually decreased and lactate dehydrogenase (LDH) gradually increased. Both SDH and LDH were gradually restored to normal levels after reoxygenation. Therefore, environmental hypoxia should be avoided as much as possible during aquaculture breeding of E. sinensis and P. sinensis. Further, since OCR will significantly increase after a short period of reoxygenation, secondary environmental hypoxia due to rapid consumption of oxygen should also be avoided in aquaculture.

Project description:Salinity plays a key role affecting ovarian development, osmoregulation and metabolism of female Chinese mitten crab, Eriocheir sinensis during reproductive migration. In this study, female E. sinensis after their puberty molt were subjected to four salinities of 0, 6, 12, and 18‰ for 40 days to investigate the salinity effects on their ovarian development as well as a range of important physiological parameters. Elevated salinity accelerated the ovarian development with ovigerous crabs found at salinity treatments of 12 and 18‰ despite no copulation had occurred. Meanwhile the survival rate of female crabs showed a decreasing trend with increasing salinity. Higher salinity also led to increased hemolymph Na+, K+, Ca2+, Cl-, and Mg2+ concentrations. The 6‰ treatment had the highest contents of hemolymph total and major free amino acids while the Na+/K+ -ATPase activity in the posterior gills was the lowest among treatments. Total n-3 polyunsaturated fatty acids (∑n-3PUFA) and n-3/n-6 PUFA ratio in the anterior gills showed a decreasing trend with salinity while 18‰ had the highest ∑PUFA and ∑n-6PUFA. The ∑n-3PUFA content and n-3/n-6 PUFA ratio of the posterior gills showed a fluctuating pattern and the highest value was detected at 0‰, while an increasing trend was found for the ∑n-6PUFA with increasing salinity. The hemolymph glucose showed a decreasing trend with increasing salinity and the highest total cholesterol in hemolymph was detected at 12‰. The 18‰ treatment had the highest levels of hemolymph γ-glutamyltransferase, alkaline phosphatase and acid phosphatase, as well as glucose, urea and acid phosphatase in hepatopancreas while the highest hemolymph superoxide dismutase and malondialdehyde were detected at 0‰. Overall, the results showed that salinity increase from freshwater to brackish conditions led to lower metabolism, accelerated ovarian development, and the appearance of ovigerous crabs without copulation in female E. sinensis post puberty molt.

Dataset Information

Characterization and expression of glutamate dehydrogenase in response to acute salinity stress in the Chinese mitten crab, Eriocheir sinensis.

Publications

Characterization and expression of glutamate dehydrogenase in response to acute salinity stress in the Chinese mitten crab, Eriocheir sinensis.

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