Embryonic lethals induced by x-iradiation of first meiotic metaphase oocytes of Habrobracon.

INVESTIGATIONS to be reported in this paper have been concerned chiefly whh X-ray-induced embryonic lethal mutations in Habrobracon. Some of the data and one of the methods have already been given (HEIDENTHAL 1952, 1953; HEIDENTHAL, C ARK and GOWEN 1955). The purpose of the author's work, as well as that of others, has been in part to study the frequency of different kinds of lethal-bearing genomes, which result from irradiation of oocytes in first meiotic metaphase, a cytologically uniform stage ( ATWOOD, VON BORSTEL and WHITING 1956; WHITING 1938,1941, 1945a,b). Estimates of genome frequency have been possible because Habrobracon is a naturally parthenogenetic organism. Lethal action can be studied in both haploid and diploid embryos. Evidence that this lethality is attributable to chromosomal (genetic) rather than to cytoplasmic injury, or a combination of the two, has been provided by the extensive work of WHITING on androgenesis (WHITING 1946, 1948, 1949, 1954, 1955). The purpose of the author's work reported here is to give further data and analysis of embryonic lethals induced by X-irradiation of first meiotic metaphase oocytes.