The control of crossing-over in the X-chromosome of Drosophila melanogaster

Influence of temperature on recombination in yeast

“…This result and the reduction in recombination in the extended region c-ad6, demonstrate that the effects of temperature upon crossing over in yeast are not confined to regions close to a centromere. In this respect these findings in yeast confirm those of Lawrence (1958Lawrence ( , 1963 in Drosophila and of McNelly-Ingle, Lamb and Frost (1966) in J'Teurospora.…”

“…This effect in yeast is similar, however, to that in Ustilago hordei (Huttig, i) and to certain findings in .Neurospora (Rifaat, 1959), in which some crosses showed less recombination at 17° C. than at 25° C. Other experiments with .Neurospora (Lawrence, 1958(Lawrence, , 1963Towe and Stadler, 1964;McNelly-Ingle, Lamb and Frost, 1966), however, in which reduced temperatures of 15° C. and i8° C. were used, have given results similar to those with Drosophila, i.e. increased recombination frequency at lower temperature.…”

“…For instance, crossing over in Habrobracon appears independent of temperature (Clark, 1943) and in Ustilago hordei, a minimum frequency at 8° C. has been found (Huttig, 1931). In Jsfeurospora crassa, various results have been obtained (Rifaat, 1959;Towe and Stadler, 1964;McNelly-Ingle, Lamb and Frost, 1966) and it appears likely that genetic background exerts an important influence (Lawrence, 1963). In general, a change of recombination frequency with temperature has appeared to be confined to regions close to the centromere.…”

Genes controlling chiasma frequency in Hordeum

“…It exhibits a continuous variation in heredity such as would arise by polygenic control, exercised mainly through genes with additive effects but partly, also, through genes with non-additive action including dominance. The dominance is in the direction of higher chiasma frequency, as in rye (Rees and Thompson, 1956; cf Sun and Rees, 1964) and Drosophila (Lawrence, 1958(Lawrence, , 1963Law, 1961). The assay described provides further information on this controlling system.…”

Environment and selection in Drosophila melanogaster

“…Yet among the agencies determining the availability of variation, that of recombination is known to vary with the temp erature of the environment (Plough, 1917), particularly in the case of the X chromosomes of the inbred lines used as parents here (Lawrence, 1958(Lawrence, , 1963. Since the average frequency of recombination between certain loci at least has been shown to be higher at i8° C. than at 25° C., it follows that we expect to observe a greater response to selection in the former environment than in the latter.…”