Investigation of the localization of dehydroepiandrosterone sulphotransferase in adult rat kidney.

Sulphotransferases are a family of enzymes involved in the metabolism and detoxification of many compounds. Dehydroepiandrosterone (DHEA) sulphotransferase (DHEA-ST), which catalyzes the sulphation of steroids such as DHEA, is present in rat liver and adrenals. Sulphated steroids are present in urine, and many other enzymes which catalyze detoxification reactions are found in the kidney. There are not previous reports of DHEA-ST localization in adult kidney. The activity of DHEA-ST was investigated in adult rat kidney by a radio-isotope assay with DHEA as the substrate. Western blotting was used to assess protein expression, and the localization of DHEA-ST was investigated by immunohistochemistry. The DHEA-ST activity in rat kidney was found to be approximately four times less than that in rat liver. In female kidney, the activity was 1.46 +/- 0.06 nmol/min/microg, and in male kidney the activity was 1.29 +/- 0.09 nmol/min/microg. Investigation of protein expression gave a single band at 35 kDa which signified the presence of this enzyme in both male and female adult rat kidneys. Localization studies showed positive staining at high intensity in the collecting ducts of the medulla and in the S3 portion of the proximal convoluted tubule in the cortex. The distribution within the proximal tubules was restricted to the brush border. Reverse-transcriptase polymerase chain reaction showed DHEA-ST RNA expression in adult rat kidney and liver. The presence of this enzyme and its location in the kidney may suggest that in situ sulphation via DHEA-ST may play an important role in the excretion of endogenous and exogenous compounds.

Reading upper and lower case on Viewdata.

The times taken to read aloud six passages of nonsense text presented in upper or lower case on an ITT Viewdata receiver were compared. Contrary to the usual finding with printed material, upper case text did not significantly retard reading.