Translocations induced by fast neutrons and X-rays in Delia antiqua

Summary A comparison was made using X-rays and fast neutrons for the induction of translocations in Delia antiqua. Using the same radiation dose, no difference in efficiency between the two radiation types could be observed. However, with fast neutrons many multiple translocations were induced, including a quadruple translocation involving 4 out of 5 autosomes. One male linked translocation was also induced.The reciprocal translocations were assigned into two classes: symmetrical and asymmetrical, and ten of the latter were chosen for inbreeding to produce homozygotes. Asymmetrical exchanges were chosen so that translocation homozygotes could be differentiated cytologically from the normal karyotype. In seven different translocations, homozygous larvae were observed, but often at a low frequency. In four of these lines, viable adult homozygotes were observed. Subsequent random sib-crossing failed to produce a homozygous line.