Transgenerational effects on Drosophila melanogaster populations detected after specific environmental changes. Patricia Ramos-Morales, Adriana MuÑoz, Blanca R. Hernandez, Hugo Rivas, Armando MuÑoz. FACULTAD DE CIENCIAS, UNAM, MEXICO.

   Introduction. The change in the inherited characteristics of biological populations occurring through successive generations leads to the emergence of new varieties and species of organisms. How much time is required for the changes to be measurable? How long the changes in environmental conditions continue to affect populations? Hydroxyurea (HxU) is an antimetabolite, which is cytostatic by inhibiting ribonucleoside reductase, and is widely used to treat some metabolic diseases. Metabolic activation of HxU increases its potential for genetic damage; being hydrogen peroxide a metabolic product of HxU. Aim: to determine the effect of HxU on the reproductive activity of exposed flies and monitoring the impact through successive generations. Methods: From 32 mM HxU, eighteen concentrations mixed on the food were assayed. Third instar larvae were fed chronically and the effects were analyzed on the adult flies. Toxicity was determined as: experimental flies/control flies; and the Sex rate as the proportion of females (or males)/total of flies into each vial. The transgenerational effect of a single exposure was established using wild type flies (wt) and insecticide resistant flies which differ in their capacity to transform xenobiotics (ORR). For the reprotoxic effect, 10 couples of treated flies were put individually into vials to recover the F1. From F2 to F4 generations, two couples from five different families were randomly chosen and transferred to fresh media to produce the next generation. Results: In the first generation, progeny from wt and ORR exposed flies was more numerous than that from unexposed flies. For F2-F4 generations, progeny from wt exposed flies trend was similar to that from control flies or larger but the reverse effect was found for ORR flies. Discussion: Hx Treatment modified the reproductive function on exposed flies and their descendents, which suggest an epigenetic potential for HxU. Acknowledgment: to the Genetic and Environmental Toxicology Program'Students.