The maternal effect and zygotic phenotype of l(1)pole hole (l(1)ph) is described. l(1)ph is a zygotic lethal mutation which affects cell division of adult precursor cells in Drosophila larvae. The locus is located in 2F6 on the salivary gland chromosome map and four alleles have been characterized. Germ-line clonal analysis of amorphic alleles indicates that l(1)ph has a maternal effect lethal phenotype. Two lethal phenotypes are observed among embryos derived from female germ-line clones homozygous for amorphic alleles dependent upon the zygotic activity of l(1)ph+ introduced via the sperm. Class 1: If no wild-type dose of the gene is introduced, embryos form abnormal blastoderms in which nuclear migration and cell formation is disrupted leading to an ill-defined cuticular pattern. Class 2: If a wild-type copy of the gene is introduced, blastoderm cells do not form beneath the pole cells (the pole hole phenotype); subsequently such embryos are missing cuticular structures posterior to the seventh abdominal segment (the torso phenotype). When the zygotic activity l(1)ph+ is modulated using position effect variegation a new phenotype is observed among class 2 embryos in which torso embryos are twisted along their longitudinal axis.
Three allelic, dominant and germline-dependent female-sterile mutations (ovo(D) mutations) can be classified according to the severity of the ovarian abnormalities that they produce. The size and frequency of +/+ germline clones, induced in ovo(D)/+ females, were compared with K10/K10 germline clones induced in K10/+ control females. The frequency of germline clones induced by irradiation of first instar larvae is similar for the three dominant alleles and K10 ; however, the clone size increased with the strength of the allele tested, compared with K10 clones. When clones were induced later in development, the clone frequencies decreased with the strength of the alleles. These results are discussed in the context of the antimorphic nature of these mutations and the characteristics of germline development. The use of these alleles as tools in the genetic analysis of development is discussed.
We have analyzed the 2E1-3A1 area of the X chromosome with special attention to loci related to embryogenesis. Published maps indicate that this chromosomal segment contains ten bands. Our genetic analysis has identified 11 complementation groups: one recessive visible (prune), two female steriles and eight lethals. One of the female sterile loci is fs(1)k10 for which homozygous females produce both egg chambers and embryos with a dorsalized morphology. The second female sterile is the paternally rescuable fs(1)pecanex in which unrescued embryos have a hypertrophic nervous system. Of the eight lethal complementation groups two are recessive embryonic lethals: hemizygous giant (gt) embryos possess segmental defects, and hemizygous crooked neck (crn) embryos exhibit a twisted phenotype. Analysis of these mutations in the female germ line indicates that gt does not show a maternal effect, whereas normal activity of crn is required for germ cell viability. Analysis of the maternal effect in germ line clones of the remaining six recessive lethal complementation groups indicates that four are required for germ cell viability and one produces ambiguous results for survival of the germ cells. The remaining, l(1)pole hole, is a recessive early pupal lethal in which embryos derived from germ line clones and lacking wild-type gene activity exhibit the "torso" or "pole hole" phenotype.
A library of monoclonal antibodies, raised against imaginal discs of Drosophila melanogaster, was screened for binding to differentiation antigens in the adult ovary by immunofluorescence. Several lectins were similarly assayed. Two antibodies, DOV 1 and DOV 2, and wheat germ agglutinin exhibited binding which was restricted to particular stages of ovarian cell differentiation. DOV 2 also showed a marked preferential binding to the cell surface of germ line cells in the ovary. A differentiation of the portion of the tunica propria covering the anterior part of the germarium was revealed by the monoclonal antibody DOV 3. Another monoclonal antibody, DOV 4, identified a molecular specialization of the chorion at the tip of the micropyle. These markers should provide tools for the molecular analysis of oogenesis.
Many genetic loci that result in lethality when mutated may also have an essential role in oogenesis. The maternal effects of EMS-induced zygotic lethal mutations at 48 loci were examined using the dominant female-sterile technique. Three categories of effects were found. In the first group (13 out of 48), no maternal effect was detected. The second set (20 out of 48) exhibited maternal effects on oogenesis, embryogenesis, or both. In 13 of this last group, only a few eggs were produced before a progressive deterioration of development occurred. It is suggested that perdurance of the wild-type gene product could produce this result. The third group (15 out of 48) produced cell lethality in germ-line clones, an effect that may be related to their role in indispensable cell functions. Three loci were found which, in germ-line clones, produced embryonic phenotypes that resemble maternal effect mutations. The implications of this study for the genetic analysis of early development are discussed.
Using the newly isolated, germ line-dependent dominant female-sterile mutation Fs(1)K1237, we have characterized the germ line or somatic line dependence of 25 X-linked recessive female-sterile mutations. Since Fs(1)K1237/+ females fail to lay eggs, only germ line cells which lose Fs(1)K1237 as a result of X-ray-induced mitotic recombination are capable of producing eggs. Such recombination events will render genes on the homologous chromosome homozygous. If this chromosome carries a recessive female-sterile mutation, the fertility will be restored only if the altered function is not required in the germ line. Using this test, we have classified 25 recessive female-sterile mutations: 12 affect germ line function, 12 affect somatic line function, and one gave an ambiguous result for which an explanation is proposed. For a few of the somatic line-dependent mutants, we found that some eggs derived from germ line clones showed the same phenotype as eggs laid by females homozygous for the recessive female-sterile mutation. These results are discussed in terms of a coincident production of clones in the follicle cells.