Maternal and Zygotic Interactions Between the Abnormal Oocyte Mutation and the SCUTE4 Inversion in Drosophila Melanogaster (original) (raw)
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Genetics, 1980
The possibility that essential loci in the zeste-white region of the Drosophila melanogaster X chromosome are expressed both maternally and zygotically has been tested. Maternal gene activity was varied by altering gene dose, and zygotic gene activity was manipulated by use of position-effect variegation of a duplication. Viability is affected when both maternal and zygotic gene activity are reduced, but not when either maternal or zygotic gene activity is normal. Tests of a set of overlapping deficiencies demonstrate that at least three sections of the zeste-white region yield maternal zygotic lethal interactions. Single-cistron mutations at two loci in one of these segments have been tested, and maternal heterozygosity for mutations at both loci give lethal responses of mutant-duplication zygotes. Thus, at least four of the 13 essential functions coded in the zeste-white region are active both maternally and zygotically, suggesting that a substantial fraction of the genome may fun...
Genetics, 1995
Studies of the abnormal oocyte (abo) gene of Drosophila melanogaster have previously been limited to the analysis of a single mutant allele, abnormal oocyte1 (abo1). The abo1 mutation causes a maternal-effect lethality that can be partially rescued zygotically by the abo+ allele and by increasing the dosage of specific regions of heterochromatin denoted ABO. This report describes the properties of abo2, a new P-element-induced allele that allowed us to reexamine the nature of maternal-effect defect. Comparisons of the phenotype of progeny of abo1/abo1 and abo1/abo2 females show that the preblastoderm lethality previously described as a component of the abo mutant maternal effect results from a recessive fertilization defect associated with the abo1 chromosome. We demonstrate here that the abo-induced maternal effect lethality occurs predominately late in embryogenesis after cuticle deposition but before hatching. The phenocritical period for zygotic rescue by heterochromatin coincid...
Viability of female germ-line cells homozygous for zygotic lethals in Drosophila melanogaster
Genetics, 1983
We have analyzed the viability of different types of X chromosomes in homozygous clones of female germ cells. The chromosomes carried viable mutations, single-cistron zygotic-lethal and semi-lethal mutations, or small (about six chromosome band) deletions. Homozygous germ-line clones were produced by recombination in females heterozygous for a n X-linked, dominant, agametic female sterile. All the zygotic-viable mutants are also viable in germ cells. Of 16 deletions tested (uncovering a total of 93 bands) only 2 (of 4 and 5 bands) are germ-cell viable. Mutations in 15 lethal complementation groups in the zeste-white region were tested. When known, the most extreme alleles at each locus were tested. Only in five loci (33%) were the mutants viable in the germ line. Similar studies of the same deletions and point-mutant lethals in epidermal cells show that 42% of the bands and 77% of the lethal alleles are viable. Thus, germ-line cells have more stringent cell-autonomous genetic requirements than do epidermal cells. The eggs recovered from clones of three of the germ-cell viable zw mutations gave embryos arrested early in embryogenesis, although genotypically identical embryos derived from heterozygous oogonia die as larvae or even hatch as adult escapers. For two genes, homozygosis of the mutations tested also caused embryonic arrest of heterozygous female embryos, and in one case, the eggs did not develop at all. Germ-line clones of one quite leaky mutation gave eggs that were indistinguishable from normal. The abundance of genes whose products are required for oogenesis, whose products are required in the oocyte, and whose activity is required during zygotic development is discussed. N important parameter of developmental genetics is the number of genes A necessary for any particular developmental process. An estimate of this is the fraction of loci in which amorphic alleles cause cell autonomous arrest of the particular developmental process. Studies with zygotic lethals have shown Research supported by F.I.S. and US-Spanish Joint Committee for Scientific and Technological Cooperation
The effect of the Curly inversions on meiosis in Drosophila melanogaster
Hereditas, 2009
In Drosophila melanogaster the interchromosomal effect of structurally homozygous In(2L + 2R)Cy on recombination in X was tested, using lethal-free inversion chromosomes (which must always lack the Cy gene). The results show that (1) with homozygous inversions, X recombination is both enhanced and redistributed in a pattern reminiscent of that obtained with heterozygous inversions, (2) different Cy chromosomes with identical inversions but differing gene contents have different effects on distribution of X recombination. The results suggest that inversion heterozygosity increases the capacity for recombination in heterologous chromosomes while specific alleles of recombination-affecting loci contained in these inversions may influence both amount and distribution of recombination.
The genetic factors altered in homozygous abo stocks of Drosophila melanogaster
Genetics, 1986
Females homozygous for the maternal-effect mutation abo (2-44.0) produce a large fraction of eggs which arrest during embryogenesis. Increasing doses of defined heterochromatic regions inherited by offspring of abo mothers from their fathers function zygotically to bring about a partial rescue of the abo-induced embryonic lethality. Another property of the abo mutation is that the severity of the maternal effect decreases when an abo stock is maintained in homozygous condition for a number of generations. Here, we show that the factors which change in homozygous abo stocks to result in the decrease in maternally induced embryonic lethality, act zygotically, dominantly and additively. More importantly, we show that the X and second chromosomes, but not the Y and third chromosomes, derived from homozygous abo stocks are, when inherited from males, more effective in promoting zygotic rescue of the abo-induced lethality than are the equivalent chromosomes derived from an abo stock maint...
Genetics, 1991
The euchromatic maternal-effect mutation abnormal oocyte (abo), of Drosophila melanogaster interacts with regions of heterochromatin known as ABO, which reside on the X, Y and second chromosomes. Here, we show that survival of progeny from abo females depends in part upon the maternal dosage of ABO heterochromatin. A comparison was made of the recovery of genotypically identical progeny from abo mothers bearing sex chromosomes of various ABO contents. The results show that the recovery of daughters was decreased if mothers were ABO-/ABO-. However, no decrease was observed if mothers were ABO+/ABO-. In addition, the survival of daughters was greater when they received an ABO-X chromosome from an ABO-/ABO+ mother rather than the father. We suggest that these results reflect a complementation or interaction between the ABO-deficient X and the ABO heterochromatin in the maternal genome. This proposed interaction could occur early in oogenesis in the mother or prior to completion of meio...
Genetics
In mutagenesis screens for recessive female sterile mutations on the second chromosome of Drosophila melanogaster 528 lines were isolated which allow the homozygous females to survive but cause sterility. In 62 of these lines early stages of oogenesis are affected, and these females usually do not lay any eggs. In 333 lines oogenesis proceeds apparently normally to stage 8 of oogenesis, but morphological defects become often apparent during later stages of oogenesis, and are visible in the defective eggs produced by these females whereas 133 lay eggs that appear morphologically normal, but do not support normal embryonic development. Of the lines 341 have been genetically characterized and define a total of 140 loci on the second chromosome. Not all the loci are specific for oogenesis. From the numbers obtained we estimate that the second chromosome of Drosophila contains about 13 loci that are relatively specific for early oogenesis, 70 loci that are specifically required in mid to late oogenesis, and around 30 maternal-effect lethals. Female Sterile Mutations 1133
Chromosomal Structure and Recombination between Inversions in drosophila Subobscura
Hereditas, 2004
Drosophila subobscura is a species with rich chromosomal polymorphism. More than 45 arrangements have been described in the O chromosome. The recombination between them is an interesting topic, because many nonoverlapping arrangements are inherited together. In the analysis of recombination between the arrangements O7 and O3 + 4 + 8, out of 415 individuals observed none was found to be recombinant. The same result was obtained in the study of the recombination between the inversions O5 and O3 + 4, in which 437 individuals were analyzed. In this case a significant non equivalent segregation was found, the O5 chromosomes being more frequent than expected. This phenomenon could be explained by three hypotheses: a meiotic drive, a greater fitness of the individuals carrying this inversion and heterotic effect of a wild chromosome in combination with a chromosome from an inbred laboratory strain. If the second hypothesis is correct, it could explain why an inversion always associated with a lethal gene in American populations is not infrequent and presents a clinal distribution in the colonized areas. Furthermore, another inversion, O22, is very similar to O5. These two inversions can be distinguished only by careful observation. Although O22 and O5 are very similar they show different behavior in the wild, probably due to the combinations of genes included in them.