Indian Society of Genetics & Plant Breeding
HERSKOWITZ and Abrahamson (1956) demonstrated that radiation doses upto
2500 r produced no observable reduction in the number of eggs laid by Drosophila
females. They also noticed that the relatively higher frequency of pseudo-crossovers
plus crossovers, as compared to gross structural changes involving the same region,
in late oocytes was due to recombination rather than to restitution. In the silkworm,
Nakao (1953) showed that the magnitude of difference in the mutation rate at specific
loci between treated and non-treated moths depended upon the X-ray dose and that,
with almost equal X-ray doses, spermatozoa entering four hours after exposure of moths
to irradiation gave a lower mutation frequency than those entering two and a half
hours after treatment. Tajima (1957) irradiated female and male germ cells with betarays at different larval stages and concluded that spermatogonia and spermatocytes
were very sensitive to radiation, while spermatids and spermatozoa were fairly
resistant.
Year: 1960
Volume: 20
Issue: 3
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906
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