Biological indicators for monitoring exposure/toxicity from III-V semiconductors.

These studies were conducted to assess alterations in renal tubule cell gene expression following in vivo exposure to the semiconductor elements indium (In), arsenic (As) or indium arsenide (InAs). Alterations in proximal tubule cell gene expression were monitored at similar tissue concentrations of In or As at various time-points following single subcutaneous (sc) injections of In, As or InAs at 0, 10 and 30 days (In: 1.5 mg/kg; As, 3 mg/kg or 0.3 mg/k; and InAs: 1000 mg/kg). Protein synthesis as monitored by incorporation of 35S methionine was not statistically increased over the 30-day period following sc injection of As, In or InAs relative to controls. Two dimensional--SDS/polyacrylamide gel electrophoresis showed that exposure to InAs stimulated the synthesis of a number of proteins with molecular masses of < 10, 18, 28, 32, 38, 42, 58, 70, 98 KDa. Exposure to As produced an increase in the expression of thirteen gene products. Indium produced similar changes at the 10-day time-point, but increased tissue accumulation of this element at 30 days markedly suppressed the stress protein response. These data indicate that induction of these specific gene expression patterns may be useful as early indicators for assessing exposure to InAs, or inorganic As, while suppression of these responses by In suggests a compromise in this basic protective mechanism.