[Pleiotropism of wh and el locus in Habrobracon juglandis].

Abstract

The two autonomously manifesting mutations, eyeless (el) and white eyes (wh), of Habrobracon juglandis were compared phenotypically with the wild-type. Eyeless reduces the compound eyes in size. The penetrance is 100%, while expressivity ranges from point-shaped ommochrome crumbs over individual facets to a small eye with abundant facets. There is no correlation between the sizes of left and right eyes. The head capsule is more deformed when the eye is smaller. The homozygote ♀♀ of wild-type have smaller eyes than the hemizygote ♂♂. This gene dose effect is still stronger in el. wh causes white eye colour which remains throughout lifetime. With regard to the amount of eye pigment the three stocks can be arranged in the following sequence: wild type >el>wh. The concentrations of ommochrome precursors, however, do not agree with this sequence. The amount of 3-hydroxykynurenine in el is the same as in wild-type; although in pupal stage the peak in the former appears earlier. The kynurenine concentration in el increases at the time of pupation and induces the beginning of pigmentation earlier than in wild-type; further this process is terminated in el earlier. In wh and in wild-type the amount of kynurenine is also the same. However, there is much less 3-hydroxykynurenine in wh than in wild-type. This is presumably due to a lower kynurenine hydroxylase activity. During the entire postembryonal development there is more xanthurenic and kynurenic acid in wh; in pupal stage, even, there is a second peak. Pupae and adults of wh have a higher kynurenine and presumably also a higher 3-hydroxykynurenine transaminase activity than wild-type. The influence of the mutation wh on the differential rates of hydroxylation and transamination is discussed in relation to the results obtained with mutants of the white locus in Drosophila.