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D Gubb

Publications and source records attributed to D Gubb.

9 recordsLinked to original sources
PubMed1993

Genetic and cytogenetic analysis of the 43A-E region containing the segment polarity gene costa and the cellular polarity genes prickle and spiny-legs in Drosophila melanogaster.

A cytogenetic analysis of the 43A-E region of chromosome 2 in Drosophila melanogaster is presented. Within this interval 27 complementation groups have been identified by extensive F2 screens and ordered by deletion mapping. The region includes the cellular polarity genes prickle and spiny-legs, the segmentation genes costa and torso, the morphogenetic locus sine oculis and is bounded on its distal side by the eye-color gene cinnabar. In addition 19 novel lethal complementation groups and two semi-lethal complementation groups with morphogenetic escaper phenotypes are described.

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PubMed1993

Genes controlling cellular polarity in Drosophila.

The control of cellular polarity is one of the least understood aspects of development. Genes have been identified in Drosophila that affect the polarity of embryonic cells in all three axes, apical-basal, proximodistal and dorsoventral. Mutations that affect adult polarity are also known and mutant flies show several types of pattern alteration, including rotations and mirror-image duplications. Imaginal discs are much greater in size, however, than the embryo, and adult structures contain very large numbers of cells, many of which are not visibly differentiated with respect to their immediate neighbours. In regions where neighbouring cells are similar to each other, the imaginal polarity mutants alter the orientation of bristles and hairs, but do not change cellular fate. Other regions, such as the tarsal segments of the legs, the ommatidia of the eye and the bracketed bristle sockets on the tibia, behave as discrete fields. Within these fields, fine-scale mirror-image reversals and pattern duplications are observed, analogous to those caused by the embryonic segment polarity mutants. Thus, the polarised transmission of information can affect either orientation or fate depending on whether cells are differentiated from their immediate neighbours. Cellular polarity will be critically dependent on both the internal cytoskeletal architecture and the spatial organisation of signal transduction molecules within the cell membrane.

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PubMed1990

A novel transvection phenomenon affecting the white gene of Drosophila melanogaster.

The zeste mutation of Drosophila melanogaster suppresses the expression of white genes in the eye. This suppression is normally dependent on there being two copies of w+ located close to each other in the genome--they may either be in cis (as in a tandem duplication of w+) or in trans, i.e. on homologous chromosomes. Duplicated w+ genes carried by a giant transposing element, TE146(Z), are suppressed by z whether they are in direct (tandem) or inverted order. The tandem form of the TE is very sensitive to a rearrangement on the homologous chromosome--many rearrangements with breakpoints "opposite" the TE's insertion site prevent the interaction between the white genes on a z background. These aberrations act as dominant suppressors of zeste that are specific to the tandemly duplicated form of TE146(Z). The inverted form of the TE146(Z) presumably pairs as a hairpin loop; this is more stable than the tandem form by the criterion that its zeste phenotype is unaffected by any of the aberrations. This effect of rearrangements has been used as the basis for a screen, gamma-ray induced aberrations with at least one breakpoint opposite the TE site were recovered by their suppression of the zeste phenotype.

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PubMed1989

Chaotic names.

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PubMed1988

A selective screen to recover chromosomal deletions and duplications in Drosophila melanogaster.

A screen is described that will select for breakpoints within a restricted chromosomal region in Drosophila. The aberrations recovered can be used to construct chromosomes carrying synthetic duplications and deletions. Such chromosomes have applications in the mapping of complementation groups at both the genetic and molecular level. In particular, breakpoints recovered after P element hybrid dysgenesis tend to be associated with P element insertion sites. Such aberration breakpoints can be genetically mapped, as synthetic deletions, and then used as transposon-tagged sites for the recovery of genomic clones.

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PubMed1982

A genetic analysis of the determination of cuticular polarity during development in Drosophila melanogaster.

The polarity mutants pk, sple, mwh, fz and in alter the orientations of cuticular processes in several regions of the body. The mutant polarity patterns are constant and do not result from alterations in cell lineage. Polarity patterns are locus specific rather than allele specific (new alleles express the same polarity patterns as the original alleles). In the wing, polarity formation is largely cell autonomous and is independent of the anteroposterior compartment boundary. By genetic and physiological manipulation it is shown that the mutant polarity patterns are unaffected by the size of the wing blade or the number of cells that form it. Mutants which remove parts of the wing margin or alter the distribution pattern of wing veins do not alter the mutant polarity patterns. Thus, neither the wing margins nor the pattern of vein tissue act as spatial references for polarity formation. The determination of mutant polarity patterns is not dependent on the overall topology of the wing blade but is region-specific. The mutants affect several independent functions. The possible wild-type function of the loci in polarity formation is discussed.

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PubMed1975

A direct visualisation of helicoidal architecture in Carcinus maenas and Halocynthia papillosa by scanning electron microscopy.

The test of the Tunicate Halocynthia papillosa is shown to have a laminate organization. Three properties of a helicoidal model can be directly observed: (1) Fibres in each lamina run parallel. (2) Fibres in adjacent laminae run at an angle. (3) In oblique section, discontinuous parabolic arcs made up of straight lengths of fibre from succeeding laminae are observed. These properties are confirmed in the cuticle of Carcinus maenas and the relationship of the pore canals to the laminar organization is discussed. It is shown by matching light and electron micrographs that the 'macrofibres' of recent workers are displaced pore canal tubules.

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PubMedDate not supplied

Spontaneous excision of a large composite transposable element of Drosophila melanogaster.

The TE1 family of transposable elements (TEs) of Drosophila consists of unusually large transposons, cytologically visible in larval polytene chromosomes as one or more bands. They are composite elements, as their termini consist of foldback (FB) sequences which are themselves transposable. The location of FB elements at the termini of transposable elements suggests that these sequences have a direct role in the genetic instability of TEs. To investigate the structural and phenotypic consequence of TE excision, we have cloned genomic DNA required for the expression of the no-ocelli (noc) gene of Drosophila; this gene has been mutated by the insertion of TE146, a member of the TE1 family carrying six polytene chromosome bands including functional copies of the white (w+) and roughest (rst+) genes. As reported here, our experiments indicate that the spontaneous excision of TE146, which results in the loss of the w+ and rst+ markers, can occur either as a single-step event or following a partial internal deletion. In either case, the end product is an imprecise excision in which a residual portion of the element, varying in size from 3 to 10 kilobases (kb), is left at the insertion site. These residual sequences share homology with the FB family. Furthermore, despite their imprecise nature, all these spontaneous excisions restore a wild-type noc+ phenotype.

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