Phenotypes and complementation of zf30C mutations. - Cook, K. (2002)
Subject: Phenotypes and complementation of zf30C mutations Phenotypes and complementation of zf30C mutations Kevin Cook Bloomington Drosophila Stock Center, Indiana University This report explores the phenotypes associated with P element insertions at the zf30C gene. When I began my analysis, the Berkeley Drosophila Genome Project (Adams et al, 2000; Spradling et al., 1999) had documented the following facts. (1) The PlacWzf30C[k02506], PlacWzf30C[k02510], PEPzf30C[EP518] and PEPzf30C[EP2228] insertions all map to the zf30C gene. (2) The PlacWzf30C[k02506] and PlacWzf30C[k02510] are nonindependent insertions and the chromosomes carrying the insertions failed to complement for lethality. (3) The chromosomes carrying PlacWzf30C[k02506] and PlacWzf30C[k02510] complemented Df(2L)30A-C and Df(2L)s1402 for lethality, but failed to complement Df(2L)N22-5. (4) The chromosome carrying PlacWzf30C[k02506] complemented Df(2L)N22-3 for lethality. Df(2L)30A-C deletes the pelo (Castrillon et al., 1993) and und (Cutforth and Gaul, 1999) genes flanking zf30C, but Df(2L)30A-C complements PlacWzf30C[k02506] and PlacWzf30C[k02510] for lethality (Adams et al, 2000; Spradling et al., 1999). This, and the fact that PEPzf30C[EP518] and PEPzf30C[EP2228] are homozygous viable, led me to examine crosses between zf30C alleles and deletions of 30C. I found that the zf30C mutations cause wing and female fertility phenotypes, but not lethality. My observations are detailed below. 1. The severity of the zf30C alleles could be ranked zf30C[k02506]<zf30C[EP518]<zf30C[EP2228] in terms of wing phenotype. zf30C[k02506] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3 or Df(2L)s1402 gave incompletely penetrant shortening of the L5 wing vein and posterior crossvein. L5 vein shortening was seen in a minority of flies and PCV shortening was uncommon. zf30C[EP518] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3, Df(2L)s1402, Df(2L)N22-5 or Df(2L)N22-14 had slightly more penetrant L5 and PCV shortening and occasional shortening of L2. In addition, I observed an incompletely penetrant outspread wing phenotype. zf30C[EP2228] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3, Df(2L)s1402, Df(2L)N22-5 or Df(2L)N22-14 gave highly penetrant L5, PCV and L2 shortening. Wings were usually outspread and, in the severest cases, dragged on the ground. I saw some nicking of the wing margins. 2. zf30C alleles showed the same allelic strength (zf30C[k02506]<zf30C[EP518]<zf30C[EP2228]) regarding female fertility. Females carrying zf30C[k02506] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3 or Df(2L)s1402 were all fertile. Females carrying zf30C[EP518] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3, Df(2L)s1402, Df(2L)N22-5 or Df(2L)N22-14 were either sterile or weakly fertile. Females carrying zf30C[EP2228] in combination with Df(2L)30A-C, Df(2L)gamma7, Df(2L)N22-3, Df(2L)s1402, Df(2L)N22-5 or Df(2L)N22-14 were invariably sterile. Females with any of the sterile genotypes laid a few nonhatching eggs and had ovaries of normal size with no overt morphological defects. 3. No male sterility was seen with any zf30C genotypes. 4. The phenotypes of zf30C[EP518] and zf30C[EP2228] in combination with zf30C[k02506] were less severe than phenotypes in combination with the deletions. No wing defects or female sterility was seen in zf30C[EP518]/zf30C[k02506] flies. zf30C[EP2228]/zf30C[k02506] flies showed only weakly penetrant L5 shortening or thinning, and females were fertile. Consistent with the BDGP results, the chromosome carrying PlacWzf30C[k02506] was lethal in combination with Df(2L)N22-5. It was also lethal with Df(2L)N22-14. This indicates the presence of at least one lethal mutation linked to the PlacWzf30C[k02506] insertion. The l(2)DB2 locus is probably mutated, since l(2)DB2[1] failed to complement the chromosome carrying PlacWzf30C[k02506]. Dp(2;Y)cb50 was capable of at least partially rescuing the wing phenotypes of the zf30C alleles in combination with Df(2L)s1402. Dp(2;Y)cb50; zf30C[k02506]/Df(2L)s1402 males were normal. Dp(2;Y)cb50; zf30C[EP518]/Df(2L)s1402 males had normal wing veins, but extremely outspread wings. Dp(2;Y)cb50; zf30C[EP2228]/Df(2L)s1402 males showed a weakly penetrant vein shortening phenotype, and outspread wings. Curiously, the outspread wing phenotype was more penetrant and pronounced in the presence of the duplication than in its absence. Loss-of-function alleles in the nearby und locus show a L5 shortening phenotype similar to that of zf30C alleles. Nevertheless, complementation tests between zf30C[k02506], zf30C[EP518] or zf30C[EP2228] and und[delta34] showed no abnormal phenotypes. References: Adams et al., 2000. The genome sequence of Drosophila melanogaster. Science 287: 2185-2195 (FBrf0126983). Castrillon et al., 1993. Toward a molecular genetic analysis of spermatogenesis in Drosophila melanogaster: characterization of male-sterile mutants generated by single P element mutagenesis. Genetics 135: 489-505 (FBrf0064394). Cutforth and Gaul, 1999. A methionine aminopeptidase and putative regulator of translation initiation is required for cell growth and patterning in Drosophila. Mech. Dev. 82(1,2): 23--28 (FBrf0108434). Spradling et al., 1999. The Berkeley Drosophila genome project gene disruption project. Single P-element insertions mutating 25% of vital Drosophila genes. Genetics 153: 135-177 (FBrf0111489)