EFFECT OF THIRAM ON CHICK CHONDROCYTES IN CULTURE

The effect of thiram, a fungicide that inc eases the incidence of tibi al dyschondroplasia (TD) in poultry, was studied in vitro using growth plate chondrocyte culture. Thiram caused a significant reduction in a lkaline phosphatase, acid phosphatase, and lactate dehydrogenase (LDH) activities at concentrations of 5 mu M and above. It was highly cytot oxic to chondrocytes at and above this concentration as determined by their ability to reduce (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo lium bromide (triazolyl blue, MTT), a marker oi cellular viability. An increase in the leakage of LDH into culture media was evident at conc entration as low as 1 mu M. Very few differences were noticed in the e lectrophoretic migration profiles of cell-extract proteins at any trea tment level relative to control. The cytotoxic effect of thiram is pos sibly due to its damaging effect on the cell membrane, which may be re sponsible for chondrocyte death.