3Alpha,5beta-tetrahydrocortisol effect on outflow facility.

3Alpha,5beta-Tetrahydrocortisol (THF) was administered topically and intracamerally to ocular normotensive cynomolgus monkeys to determine whether it affects outflow facility. Monkeys received THF either topically at a dose of 2 x 5 microl drops of 300 microg/10 microl twice daily for 4 days (n = 4) or 3 times daily for 10 days (n = 4) with 10% DMSO as vehicle to the control eye, or intracamerally via 2 ml anterior chamber (AC) exchange of 30 microg/ml THF with vehicle, 0.1% DMSO, to the control eye followed by a second AC exchange using 300 microg/ml THF with vehicle to the control eye. Outflow facility was measured by a two-level constant pressure AC perfusion after administration of eye drops or after baseline outflow facility measurement and AC exchange with THF solution. The results showed no effect on outflow facility in normotensive cynomolgus monkeys.

Stabilizing Selection for Pupa Weight in TRIBOLIUM CASTANEUM.

Ninety-five generations of stabilizing selection for pupa weight in Tribolium castaneum resulted in a significant decrease in phenotypic variance, moderate reductions in additive genetic variance, but only slight changes in heritability for the trait. Sterility was significantly lower and the average number of live progeny per fertile mating was significantly higher in populations where stabilizing selection was practiced as compared with random selected populations. The results indicate that more genetic variability is being maintained than would be expected unless a fraction of the genes have a heterozygote advantage on the fitness scale. The reduction in phenotypic variance indicated that the populations with stablizing selection became somewhat more buffered against environmental sources of variation over the course of the experiment.