SECTION 10 



DEVELOPMENTAL GENETICS 



10.1. Hereditary Ovarian Tumours of Drosophila. 

 R. C. King (Evanston, U.S.A.). 



The hereditary ovarian tumours of D. melano- 

 gaster demonstrate that a complex genetic 

 system plays a decisive role in restricting the 

 multiplication of the cells destined to become 

 incorporated into an ovarian follicle. Three 

 recessive genes are known which cause in the 

 ovaries of adults uncontrolled cell proliferation 

 which results eventually in female sterility. The 

 genes in question are female-sterile (fes), narrow 

 {nw), and fused (fu). Females homozygous for/<?.s 

 or nw have ovaries which are completely tumor- 

 ous at the time of eclosion; whereas freshly 

 eclosedfu females show no tumours. Tumours be- 

 gin to appear on the second day, however, ande- 

 ventually the fu ovary becomes completely tumor- 

 ous. With respect to fu a study of eight alleles of 

 independent origin has demonstrated that in each 

 case tumors eventually form in the ovaries of 

 homozygotes. However, different fu alleles can be 

 distinguished on the basis of the speed with which 

 tumorous chambers appear in the ovary. 

 Dietrich Bodenstein and I have studied the 

 development of ovarian implants which were 

 made using as hosts or donors phenotypically 

 wild type adults or flies homozygous for fes or fu. 

 Implants from fes or fu females behave autonom- 

 ously when left in wild type female hosts for as 

 long as 6 days. Implants from + donors appear 

 cytologically normal after developing in fes or fu 

 abdomens for times as long as 9 and 12 days, 

 respectively. Thus there is no evidence for diffu- 

 sible tumorigenic agents as initiating factors in 

 the development of the ovarian tumours charac- 

 teristic of fes or fu homozygotes. 



10.2. Studies on the Aberrant Function of the Mal- 

 pighian Tubes in the Drosophila Mutant rosy. 



Ilse Schwinck (Storrs, U.S.A.). 



Experimental studies of the ontogeny of the 

 pleiotropic pattern of rosy (ry) mutants and 

 maroon-like (ma-l) mutants indicate that the 

 Malpighian tubes perform a central function in 



the aberrant pteridine and purine metabolism of 

 these mutants. W As compared to wild type, the 

 Malpighian tubes of the rosy mutant are shorter 

 and cells appear swollen. In all developmental 

 stages some globules and conglomerates of 

 globules, composed of fluorescent pteridines, are 

 found in the lumen of the tubes; the globules are 

 excreted by larvae and flies. The first occurrence 

 of the aberrant metabolites in the lumen can be 

 observed several hours before hatching from the 

 egg. During the major time of metamorphosis 

 no formation of new globules was found. 

 However, in old pupae about 10 hr before emer- 

 gence, small globules appear in a very regular 

 distribution in the lumen of the tubes, becoming 

 larger approaching emergence. The relation of 

 these findings to the other pleiotropic characters 

 will be discussed. 



Hadorn and Schwinck, Z. Vererbungslehre 

 87, 1956; Schwinck, Proc. Xth Internat. 

 Congr. of Entomology, Montreal, 1956, Vol. 2, 

 1958; Schwinck, DIS 34, 1960; Ur- 

 sprung, Z. Vererbungslehre 92, 1961. 



10.3. 



Studies on the Female-sterile Mutant deep 

 orange of Drosophila melanogaster. John C. 

 Lucchesi (Berkeley, U.S.A.). 



A high percentage of eggs laid by dor/dor 

 females, mated to dorjY or +/Y males, are 

 unfertilized: 33.7 per cent and 10.7 per cent, 

 respectively (these frequencies were correlated 

 to the fact that +/Y males inseminate females 

 more readily than dor/Y males). In addition, 

 about 6 per cent of the eggs from dor females are 

 beyond metaphase I when they are fertilized. 

 A disturbance in folic acid metabolism, 

 resulting in abnormal oogenesis (King and 

 Sang, 1959), is suggested as an explanation 

 of the high frequency of unfertilized and belatedly 

 fertilized eggs from inseminated dor females, and 

 as a possible cause for the nature of dor cyto- 

 plasm. Folic acid is structurally and functionally 

 related to the pterins (involved in eye pigment 



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