Decreased synthesis of hepatic satellite DNA in pyrrolizidine alkaloidosis of the sheep.

the proportion of heavy satellite in the DNA isolated from the livers of sheep suffering from experimental pyrrolizidine alkaloidosis is significantly lower (3.5%) than that found in the DNA from lovers of normal sheep (12%). Dehydroheliotridine, the major unbound, relatively stable metabolite of lasiocarpine and heliotrine, the alkaloids used in the study, was found to inhibit selectively the semiconservative replication of the satellite DNA in cultures of ovine kidney cells. It is suggested that the inhibition of the synthesis of satellite DNA may be related to an attack by the metabolite on the pericentromeric region where the majority of the satellite sequences are located.