Immunolocalization and Changes in Expression Levels of Glyceroporin HC-3 in Several Tissues of Gray Tree Frogs, Hyla chrysoscelis Under Different Physiological Conditions

by Yaganti, Sushmita

Previous studies show that aquaporin HC-3 in gray tree frogs, Hyla chrysoscelis, a homolog of mammalian AQP3 is an aqua glyceroporin also responsible for freeze tolerance. Our study tried to localize and compare the protein expression levels of aquaporin HC-3 in seven different organs of gray tree frogs under five different physiological conditions using immuno histofluorescence and western blot. HC-3 was immunolocalized in the epidermis and dermis of the skin, basolateral portion of the collecting ducts in the kidney, red blood cells in the liver and other tissues, muscle Schwann cells and the basolateral portion of the large intestine epithelial membrane. HC-3 cannot be immunolocalized in the stomach and the small intestine tissues. The basolateral expression of aquaporin HC-3 in the epidermis of the skin is similar to the expression in the mammalian skin. The intensity of the labeling was different in the various physiological conditions. There was a noticeable increase in the intensity of the HC-3 expression in warm (hydrated, 23º C, control) skin, kidney and liver compared to dehydrated (loss of 20% of standard body mass over one week at 23º C) and the cold ( hydrated 4º C). The intensity of labeling in large intestine had varied pattern with more expression in the warm, slightly less in the cold and absolutely negligible in the other conditions. The up-regulation of the aquaporin HC-3 protein expression in the dehydrated skin and the kidney may be due to its regulated role in the water conservation whereas its up-regulation in the cold liver can be due to synthesis and release of glycerol in this organ.