کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1976707 1060701 2007 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Air-breathing catfish, Clarias batrachus upregulates glutamine synthetase and carbamyl phosphate synthetase III during exposure to high external ammonia
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Air-breathing catfish, Clarias batrachus upregulates glutamine synthetase and carbamyl phosphate synthetase III during exposure to high external ammonia
چکیده انگلیسی

We assessed the possible upregulation of glutamine synthetase (GS) and typical ‘fish type’ carbamyl phosphate synthetase III (CPS III) in detoxification of ammonia in different tissues of the walking catfish (Clarias batrachus) during exposure to 25 mM NH4Cl for 7 days. Exogenous ammonia led to an increase in ammonia and urea concentrations in different tissues. The results revealed the presence of relatively high levels of GS activity in the brain, liver and kidney, unexpectedly, also in the muscle, and even higher levels in the intestine and stomach. Exposure to high external ammonia (HEA) caused significant increase of activities of GS, CPS III and CPS I-like enzymes, accompanied with the upregulation of GS and CPS III enzyme proteins in different tissues. Exposure to HEA also led to a sharp rise of plasma cortisol level, suggesting being one of the primary causes of upregulation of GS and CPS III enzymes activity. Liver perfusion experiments further revealed that exposure to HEA enhances the capacity of trapping ammonia to glutamine and urea by the liver of walking catfish. These results suggest that the upregulation of GS and CPS III activity in walking catfish during exposure to HEA plays critical roles to ameliorate the toxic ammonia to glutamine, and also to urea via the induced ornithine–urea cycle possibly through the involvement of cortisol.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology - Volume 147, Issue 3, July 2007, Pages 520–530
نویسندگان
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