Cloning Of Medaka Gill Na～+-K～+-ATPase Genes: Effects Of Hydrocortisone On Transcriptional Expression

Hydrocortisone, as an environmental pollutant, research of its ecological toxicity has not been reported. Normal changes of cortisol in serum plays a critical role in the regulation of saturation balance for migration process of fish, therefore, disruption of normal serum coritsol balance induced by environmental cortisol could possibly cause the failure of regulation of saturation pressure for migration process of fish.At present,study of mechanisms of saturation pressure regulation in fish have reached molecular level, it shows that gene expression of Na ~+-K~+-ATPaseαandβare associated with Na ~+-K~+-ATPase activity which is critical to regulation of saturation pressure, and cortisol is mediated by glucocorticoid receptor(GR), which regulates gene expression of. Na~+- K~+-ATPaseαandβ. However, the effects of environmental cortisol on the gene expression of GR, Na ~+-K~+-ATPaseαandβin the gill have not been reported. Therefore, medaka were selected as experimental animals, in a perspective of gene expression, the present study is to investigate the effects of cortisol on the gene expression of Na ~+-K~+-ATPaseαandβ.Combined bioinformatics with molecular biology technology, sequence segments of three genes of GR, Na ~+-K~+-ATPaseαandβhave been coloned and identified by analysis. Real-time RT-PCR method for detecting gene expression of GR, Na ~+-K~+-ATPaseαandβin the medak has been established by applying the above method , It suggests that three genes of GR, Na ~+-K~+-ATPaseαandβare expressed in gill, brain, eye, intestine, muscle, liver and spleen; and expression levels of Na~+-K~+-ATPaseαgene in various tissues are: gill> intestine≈liver> eye> brain, expression levels of Na~+-K~+-ATPaseβin various tissues are: intestine> spleen> gill> muscle≈liver> eye> brain; expression levels of GR gene in various tissues are: gill> intestine≈liver> muscle> eye> brain. The above results will provide fundamental data for molecular mechanism study of saturation pressure regulation, immunal inhibition , neural cell excitation and so on.This research result indicates that after acclimation to saline water of 15g/L, levels of Na~+-K~+-ATPaseαand GR mRNA in the gill increase significantly, and levels of Na~+-K~+-ATPaseβmRNA vary insignificantly. After medak in saline water of 15g/Lwere transferred to freshwater, expression levels of three genes were measured in different interval of time.