THE EFFECTS OF ACUTE GAMMA IRRADIATION ON THE BRINE SHRIMP, ARTEMIA. II. FEMALE REPRODUCTIVE PERFORMANCE

¹ Genetics Department, North Carolina State University, Raleigh, North Carolina 27607

Treated females were completely infecund after doses of 10-100 kR. Reduced fecundity resulted from doses of 1-5 kR. This is ascribed to oogonial lethality, and it is proposed that the Artemia ovary contains a non-exhausted oogonial stem-cell component which contributes to each successive brood. Additional causes of reduced brood size may be nutritional inadequacies and other physiological damage induced by the treatment. Sterility was almost complete after 5 kR.

Cyst hatchability data revealed no detectable dominant lethality after 1 kR, although such effects did occur after 2 and 5 kR. Some of the failure in hatching reflects probable physiological damage to the shell glands, as well as other physiological and genetic components.

The average number of broods was significantly decreased after 2 and 5 kR. Much of this reduction resulted from the absence of entire broods from the recorded data. Viviparity was also inhibited at these doses.

Data for survival to adulthood, adult mortality and reproductive patterns demonstrate that genetic damage was present in those animals descended from oocytes which had been treated with 2 or 5 kR. No definite decrease in survival to adulthood was found in animals descended from treated oogonia after 1 or 2 kR. Sex ratios were not significantly changed with any dose.