Browsing Department of Animal Biology by Subject "11β-Hydroxysteroid dehydrogenase"
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ItemCloning, expression and enzyme activity analysis of testicular 11β-hydroxysteroid dehydrogenase during seasonal cycle and after hCG induction in air-breathing catfish Clarias gariepinus( 2010-05-01) Rasheeda, M. K. ; Kagawa, H. ; Kirubagaran, R. ; Dutta-Gupta, A. ; Senthilkumaran, B.A full-length cDNA encoding 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) was cloned from testis of air-breathing catfish, Clarias gariepinus which showed high sequence homology to zebrafish and eel. The open reading frame of 11β-HSD2 was then transfected to COS-7 cells, which converted 11β-hydroxytestosterone (11-OHT) to 11-ketotestosterone (11-KT). Using NAD+, 11β-HSD2 from testicular microsomes oxidized 11-OHT with apparent Km 56±4nM and Vmax 55±6pmol/h/mgprotein values. Tissue distribution analysis revealed prominent expression in testis, anterior kidney, liver and gills. Expression of 11β-HSD2 in testis and serum levels of 11-KT were high in the prespawning phase. Administration of human chorionic gonadotropin (hCG) during prespawning and resting phases revealed initial rise in 11β-HSD2 transcript at 4h followed by gradual increase at 8h, 12h and peaking at 24h, only in testis of prespawning phase. Rate of conversion of 11-OHT to 11-KT by testicular microsomes during different testicular phases and after hCG administration corroborated well with the expression of 11β-HSD2. Ontogeny study indicated that this enzyme is expressed during testicular development. Thus the spatio-temporal expression supported with putative dehydrogenase activity and circulating 11-KT levels clearly suggest a major role for 11β-HSD2 during testicular differentiation and seasonal testicular cycle in catfish. © 2010 Elsevier Ltd.
ItemThiourea-induced alteration in the expression patterns of some steroidogenic enzymes in the air-breathing catfish Clarias gariepinus( 2005-04-01) Rasheeda, M. K. ; Sreenivasulu, G. ; Swapna, I. ; Raghuveer, K. ; Wang, D. S. ; Thangaraj, K. ; Gupta, A. D. ; Senthilkumaran, B.Previous study from our laboratory on thiourea-induced thyroid hormone depletion in mature male catfish demonstrated that thyroid hormones play a significant role in testicular function. In the present study, we aimed to analyze the changes in the expression pattern of several steroidogenic enzyme genes after thyroid hormone depletion using semi quantitative RT-PCR in both adult male and female catfish. There was a marked decrease in the 11 β-hydroxylase expression in the testis and liver while no change was observed in case of kidney. A significant decrease in 11 β-hydroxysteroid dehydrogenase transcript level in testis, liver and kidney were observed in the thiourea treated males. The results obtained corroborated with our earlier findings of testicular regression after thyroid hormone depletion. In females, expression of aromatase transcript increased in experimental group compared to control. There was no considerable change observed in the transcript level of 3β-hydroxysteroid dehydrogenase, P450 17α-hydroxylase/C17-20-lyase, and 20β-hydroxysteroid dehydrogenase in both males and females. Thus, thyroid hormones might exert modulating effect on steroidogenic enzyme genes at the transcription level. © Springer Science+Business Media B.V. 2006.