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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 199 (1991), S. 387-396 
    ISSN: 1432-041X
    Keywords: Pc group ; Ultrabithorax ; Antennapedia ; Sex combs reduced
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Members of thePolycomb (Pc) group of genes are required for the correct determination of segment identity, and are thought to be negative regulators of thebithorax andAntennapedia complexes. This hypothesis has been tested molecularly for only some members of thePc group. Here, we examine the distribution ofUltrabithorax (Ubx),Antennapedia (Antp), andSex combs reduced (Scr) proteins in the epidermis, central nervous system, and midgut of embryos homozygous for mutations in tenPc group genes. We show that zygotic loss of mostPc group genes causes ectopic expression ofUbx andAntp, but that there are differences in time and tissue-specificity. FivePc group mutations lack midgut constrictions and also exhibit ectopic or suppressedUbx expression and suppression ofAntp expression. Distribution ofAntp is upset earlier than distribution ofUbx in the central nervous system of everyPc group mutant affecting both genes. Loss of the zygotic products ofPolycomb, extra sex combs, andAdditional sex combs cause ectopic expression ofScr in epidermis, and allPc group genes exceptPsc have suppressedScr expression in the nervous system. These results are discussed with respect to the function of thePc group.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-4623
    Keywords: Polycomb group ; Segmentation genes ; Drosophila melanogaster ; Central nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutations in severalPolycomb (Pc) group genes cause maternal-effect or zygotic segmentation defects, suggesting thatPc group genes may regulate the segmentation genes ofDrosophila. We show that individuals doubly heterozygous for mutations inpolyhomeotic and six otherPc group genes show gap, pair rule, and segment polarity segmentation defects. We examined double heterozygous combinations ofPc group and segmentation mutations for enhancement of adult and embryonic segmentation defects.Posterior sex combs andpolyhomeotic interact withKrüppel 2 and enhance embryonic phenotypes ofhunchback andknirps, andpolyhomeotic enhanceseven-skipped. Surprisingly, flies carrying duplications ofextra sex combs (esc), that were heterozygous for mutations ofeven-skipped (eve), were extremely subvital. Embryos and surviving adults of this genotype showed strong segmentation defects in even-numbered segments. Antibody studies confirm that expression ofeve is suppressed by duplications ofesc. However,esc duplications have no effect on other gap or pair rule genes tested. To our knowledge, this is only the second triplo-abnormal phenotype associated withPc group genes. Duplications of nine otherPc group genes have no detectable effect oneve. Expression ofengrailed (en) was abnormal in the central nervous systems of mostPc group mutants. These results support a role forPc genes in regulation of some segmentation genes, and suggest thatesc may act differently from otherPc group genes.
    Type of Medium: Electronic Resource
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