The Pacific white shrimp, Litopenaeus vannamei, is widely farmed in China. Salinity is a major environmental factor that affects its growth and distribution. Crustacean hyperglycemic hormone is verified to participate...The Pacific white shrimp, Litopenaeus vannamei, is widely farmed in China. Salinity is a major environmental factor that affects its growth and distribution. Crustacean hyperglycemic hormone is verified to participate in ion transport in response to the salinity challenge mediated by endocrine neurotransmitters(biogenic amines, BAs). In the present study, the contents of BAs and expressions of their receptors were detected in gills of Litopenaeus vannamei exposed to low salinity. The intracellular signaling molecules such as cyclic adenosine monophosphate(cAMP), protein kinase A(PKA), 14-3-3 protein, FXYD2 protein and cAMP response element-binding protein(CREB) were detected. The effects of low salinity on the expressions of Na^+-K^+-ATPase, Na^+/K^+/2 Cl-co-transporter and Cl-transporter and activity of Na^+-K^+-ATPase were also analyzed. The results showed that dopamine and epinephrine concentrations and their receptor expressions were significantly affected by low salinity. The changes of c AMP and PKA were obvious and the expressions of 14-3-3 and FXYD2 peaked at early stages. However, the expression of CREB was only significantly up-regulated on day 9. The activity and expression of Na^+-K^+-ATPase(α subunit) reached a peak on day 1. The expressions of Na^+/K^+/2 Cl-co-transporter and Cl-transporter up-regulated obviously. It suggests that BAs can activate the cAMP-PKA pathway, which further acts on the 14-3-3 and FXYD2 proteins, and ultimately improve the activity of Na^+-K^+-ATPase. Furthermore, after BAs stimulate the cAMP-PKA pathway, PKA phosphorylates the transcription factor CREB and regulates the expressions of ion transport enzymes/transporters. The results in this study are helpful for understanding the response mechanism of endocrine neurotransmitters on osmoregulation in crustaceans.展开更多
This study investigated the effects of ammonia-N(control and 1 and 5 mg L^(-1)) on the changes of metabolic enzymes activities and nitrogenous compounds levels in the gills, hepatopancreas, muscles, and hemolymph of t...This study investigated the effects of ammonia-N(control and 1 and 5 mg L^(-1)) on the changes of metabolic enzymes activities and nitrogenous compounds levels in the gills, hepatopancreas, muscles, and hemolymph of the swimming crab Portunus trituberculatus. Results showed that the levels of hemolymph ammonia increased significantly at 6 h and then decreased to control level at 12 h. The activities of key enzymes involved in biosynthesis pathways of glutamine(Gln) and urea, such as glutamate dehydrogenase(GDH), glutamine synthetase(GS), and arginase(ARG), increased remarkably in different tissues of P. trituberculatus. Gln level was the highest in muscles, while urea content was the largest in hepatopancreas. The m RNA expression level of xanthine dehydrogenase(XDH) was downregulated sharply in gills but upregulated in the hepatopancreas and muscles. A small amount of uric acid was detected in the hemolymph. This result suggests that Gln in muscles may be used as an intermediary nitrogen repository, while urea may be primarily synthesized in the hepatopancreas and then transferred to other tissues via the hemolymph. Uric acid could be synthesized by the anabolism of purine nucleotides, in additon to the inhibitory activities of gills. In addition, the levels of Gln, urea and uric acid exhibited dose-and time-dependent effects with ammonia content. Therefore, P. trituberculatus could possibly convert ammonia into Gln, urea, or uric acid to detoxify ammonia during high ambient ammonia-N stress.展开更多
基金supported by State Oceanic Administration Specific Public Project of China (No. 201305005)the National Natural Science Foundation of China (No. 31072193)
文摘The Pacific white shrimp, Litopenaeus vannamei, is widely farmed in China. Salinity is a major environmental factor that affects its growth and distribution. Crustacean hyperglycemic hormone is verified to participate in ion transport in response to the salinity challenge mediated by endocrine neurotransmitters(biogenic amines, BAs). In the present study, the contents of BAs and expressions of their receptors were detected in gills of Litopenaeus vannamei exposed to low salinity. The intracellular signaling molecules such as cyclic adenosine monophosphate(cAMP), protein kinase A(PKA), 14-3-3 protein, FXYD2 protein and cAMP response element-binding protein(CREB) were detected. The effects of low salinity on the expressions of Na^+-K^+-ATPase, Na^+/K^+/2 Cl-co-transporter and Cl-transporter and activity of Na^+-K^+-ATPase were also analyzed. The results showed that dopamine and epinephrine concentrations and their receptor expressions were significantly affected by low salinity. The changes of c AMP and PKA were obvious and the expressions of 14-3-3 and FXYD2 peaked at early stages. However, the expression of CREB was only significantly up-regulated on day 9. The activity and expression of Na^+-K^+-ATPase(α subunit) reached a peak on day 1. The expressions of Na^+/K^+/2 Cl-co-transporter and Cl-transporter up-regulated obviously. It suggests that BAs can activate the cAMP-PKA pathway, which further acts on the 14-3-3 and FXYD2 proteins, and ultimately improve the activity of Na^+-K^+-ATPase. Furthermore, after BAs stimulate the cAMP-PKA pathway, PKA phosphorylates the transcription factor CREB and regulates the expressions of ion transport enzymes/transporters. The results in this study are helpful for understanding the response mechanism of endocrine neurotransmitters on osmoregulation in crustaceans.
基金supported by the Natural Science Foundation of Shandong Province, China (No. ZR2016 CM21)
文摘This study investigated the effects of ammonia-N(control and 1 and 5 mg L^(-1)) on the changes of metabolic enzymes activities and nitrogenous compounds levels in the gills, hepatopancreas, muscles, and hemolymph of the swimming crab Portunus trituberculatus. Results showed that the levels of hemolymph ammonia increased significantly at 6 h and then decreased to control level at 12 h. The activities of key enzymes involved in biosynthesis pathways of glutamine(Gln) and urea, such as glutamate dehydrogenase(GDH), glutamine synthetase(GS), and arginase(ARG), increased remarkably in different tissues of P. trituberculatus. Gln level was the highest in muscles, while urea content was the largest in hepatopancreas. The m RNA expression level of xanthine dehydrogenase(XDH) was downregulated sharply in gills but upregulated in the hepatopancreas and muscles. A small amount of uric acid was detected in the hemolymph. This result suggests that Gln in muscles may be used as an intermediary nitrogen repository, while urea may be primarily synthesized in the hepatopancreas and then transferred to other tissues via the hemolymph. Uric acid could be synthesized by the anabolism of purine nucleotides, in additon to the inhibitory activities of gills. In addition, the levels of Gln, urea and uric acid exhibited dose-and time-dependent effects with ammonia content. Therefore, P. trituberculatus could possibly convert ammonia into Gln, urea, or uric acid to detoxify ammonia during high ambient ammonia-N stress.
