Complex Y-linked translocations in Delia antiqua produced by irradiation of a fertile Y-linked translocation

Abstract

SUMMARYIn the onion fly, Delia antiqua. a fertile, Y-linked translocation involving chromosomes Y and 2 was irradiated with fast neutrons to induce new complexes involving the Y-chromosome. This chromosome is male determining in the onion fly. Such complexes can be used for the development of genetic sexing systems and also for the introduction of sterility into field populations following release.Irradiation reduced egg fertility by 54 per cent and significantly reduced larval survival but it had no effect on the F1 sex ratio. By measuring the fertility of 807 F1 males following outcrossing, 112 semi-sterile progenies were isolated of which 11 were lost, 29 showed no inheritance of the semi-sterility, 59 were new autosomal translocations and 13 were new complex Y-linked translocations. This classification was accomplished by checking the fertilities of outcrossed F2 males and females. Following cytological observation it was revealed that one of these new complexes involved four chromosome pairs, the remainder involved three. There appeared to be no correlation between the fertility of the translocation and the complexity of the rearrangement. The utilization of these rearrangements in the development of the genetic sexing technique for the onion fly is discussed, together with an assessment of their use for fertility reduction in natural populations.

Methodology of translocation production and stability of translocations in the Mediterranean fruit fly, Ceratitis capitata Wied. (Dipt., Tephritidae)

“…Therefore a reasonable number of male-linked translocations can be produced without having to test hundreds of strains. This contrasts with the onion fly Delia untiquu where the Y-chromosome only comprises 4 YO of the mitotic chromosome length (ROBINSON and VAN HEEMERT 1981a).…”

“…Whereas in D. antiquu irradiation with fast neutrons that reduced fertility by 54 % resulted in a yield of 8.92 Yo translocations in F, (ROBINSON and VAN HEEMERT 1981a), in C. cupitata 23.5 % of F,-males were partially sterile, when P-males were irradiated with xrays reducing fertility by 47.7 % or 53.6 %. Results obtained from irradiation experiments using x-rays or fast neutrons are comparable as it was found that there is no significant difference in translocation frequencies induced by either kind of irradiation (WIJNANDS-STAB and VAN HEEMERT 1974;ROBINSON and VAN HEEMERT 1981b). FOSTER et al (1980) found a reversion of a Y-linked 3 chromosome double translocation in the sheep blow fly Luciliu cuprina.…”