Retinal image size triggers obstacle avoidance in flying locusts

d8 99 + + 335 568 y w 25-w 1-y 1-362 568 meiotic recombination between the two Y's can practically be excluded; it lies definitely under 2 %. The possibility of X-Y recombination in female meiosis has also been tested. The 362 male offspring of In(1)sc4LscSR,y sc4scSw/In(1)sc 4L scSR,y sc4scSw/w+W y+ $ 9 x wild-type d d showed the expected genotypes (Fig. 2, Table 4) with the exception of two recombinants that, again, most probably result from exchange between one of the X's and a euchromatic section within the w+Y y+ chromosome. Mitotic recombination has been induced by treating larvae 42-44 h after egg deposition with X-rays (100 kV, 8 mA, FD 10 cm, 1.7 mm Al-filter, exposure time 1.5 rain, corresponding to 1480 _+ 20 R); or with mitomycin C (1.5 ml 1.2 mM mitomycin C in 0.5 % saccharose solution, 2.5 h feeding time). Three days after hatching adults were inspected for single and twin mosaic spots in their eyes. Control recombination frequencies depend upon the distance between cen-tromere and marker, in our case almost the whole length of the X-chromosome; they lie below 0.5 % [1]. On the y+Y map chromosome see [7, 8], on zeste see [4].