Activity and expression of aspartate aminotransferase during the reproductive cycle of a fresh water fish, Clarias batrachus |
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Authors: | AS Srivastava I Oohara T Suzuki SN Singh |
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Institution: | (1) Metabolism Section, Fish Nutrition Division, National Research, Institute of Aquaculture, Nansei, Watarei, Mie, 516–0193, Japan;(2) Centre of Advanced Study in Zoology, Banaras Hindu University, Varanasi-, 221 005, India |
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Abstract: | Aspartate amino transferase (AspT; EC: 2.6.1.1) is one of the key enzyme of aspartate malate shuttle and non-essential amino acid metabolism. In order to clarify the change of the activities of both cytosolic (c-) and mitochondrial (m-) AspT isoenzymes during the different reproductive stages of Clarias batrachus, an air-breathing carnivorous freshwater fish, the c- and m- AspT activities were measured spectrophotometrically in liver, heart, kidney, brain and ovary during the pre-spawning, spawning and post-spawning phases of the annual reproductive cycle of this fish. Maximum activities were observed during the spawning phase, followed by pre- and post-spawning phases. The native agarose gel electrophoretic pattern revealed two AspT forms, c-AspT and m-AspT, throughout the pre- to post-spawning phases. However, the spawning phase was marked by the expression of an additional anionic form of c-AspT in all tissues studied. These results indicate a distinct utilization of aspartate particularly in the spawning phase in fish in the central metabolic path via transamination reactions, and suggest a control of the enzyme activity by the expression of the additional c-AspT gene, especially at the spawning phase. |
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Keywords: | AAT AspT GOT isoenzymes |
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