ABSTRACT
Studies in 2 large-animal species have shown that continued ingestion of a mutagen increases sister chromatid exchanges (SCE) in circulating lymphocytes at rates directly related to the accumulated dose but differing between species. Groups of 3 pigs received daily oral doses of 0, 1.25, or 2.50 mg/kg body weight of 7,12-dimethylbenzanthracene (DMBA) for 160 consecutive da; similar groups of sheep received 0, 0.625, or 1.25 mg/kg daily for up to 114 da. Lymphocytes taken at 3-wk intervals from pigs and every 2 wk from sheep were cultured, and 25 randomly selected second-division metaphases from each culture were scored for SCE. Swine lymphocytes had elevated numbers of SCE at the earliest sampling times after DMBA feeding was begun. Sister chromatid exchanges continued to increase gradually among pigs consuming 1.25 mg/kg/da for 160 da whereas those on 2.5 mg/kg tended to plateau at approximately 2.5 times their pretreatment level after some 80 da. Sheep treated with comparable levels of DMBA (1.25 mg/kg) exhibited a much more rapid rise in SCE than pigs; within 40 da their SCEs were at 4 times the control level and animals were exhibiting toxicity symptoms. Low-dose sheep also showed a rapid initial increase but plateaued at about 2.5 times the control level beyond 40 da.
Subject(s)
Lymphocytes/drug effects , Mutagens/pharmacology , Sister Chromatid Exchange/drug effects , 9,10-Dimethyl-1,2-benzanthracene/administration & dosage , 9,10-Dimethyl-1,2-benzanthracene/pharmacology , Administration, Oral , Animals , Cell Division/drug effects , Cells, Cultured , Female , Male , Mutagens/administration & dosage , Sheep/genetics , Swine/genetics , Time FactorsABSTRACT
Sister-chromatid exchanges were scored at 3-week intervals in lymphocytes of female swine ingesting daily doses of 1.25 or 2.50 mg/kg of 7,12-dimethylbenzanthracene (DMBA) for 160 days. Exchanges increased with time for about 120 days then reached a plateau at approximately 2.5 times their pretreatment level. No increase in chromosome aberrations could be identified as resulting from ingestion of the chemical. Week-old progeny of animals that had ingested the chemical throughout pregnancy showed no increase of exchanges in their peripheral lymphocytes.
Subject(s)
9,10-Dimethyl-1,2-benzanthracene/pharmacology , Benz(a)Anthracenes/pharmacology , Crossing Over, Genetic/drug effects , Lymphocytes/drug effects , Sister Chromatid Exchange/drug effects , 9,10-Dimethyl-1,2-benzanthracene/administration & dosage , Administration, Oral , Animals , Female , Maternal-Fetal Exchange , Pregnancy , Swine , Swine, MiniatureABSTRACT
The numbers of sister chromatid exchanges in lymphocytes grown in varying concentrations of serum from different sources indicated that some sera contain a factor, probably introduced as a contaminant, which induces SCEs. Sera from 6 animals showed no evidence of a difference in baseline SCE levels due to the donor of the serum.
Subject(s)
Crossing Over, Genetic , Lymphocytes/physiology , Perissodactyla/blood , Sister Chromatid Exchange , Animals , Cattle , Cell Division , Cells, Cultured , Culture Media , Drug Contamination , Female , Fetal Blood , Humans , Lymphocytes/cytology , Male , SwineABSTRACT
Peripheral blood lymphocytes from cattle, pigs, sheep and humans were cultured in the presence of 0.5, 1, 2, 5, 10 or 20 micrograms/ml of BrdUrd. Sister-chromatid exchanges were scored in 25 second-division metaphases from each donor at each level of the chemical. Dose--response curves for all 4 species increased steeply to 2 micrograms/ml; above this level, SCE numbers increased less rapidly but maintained a linear relationship to increasing BrdUrd concentration. Comparisons of the straight-line portions of the dose--response curves showed human cells to be significantly more sensitive to increasing BrdUrd level than cow or pig cells and different from sheep at the 10% level of confidence.
