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  • Articles  (24)
  • Articles: DFG German National Licenses  (24)
  • Drosophila
  • Springer  (24)
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  • Nature America Inc.
  • Periodicals Archive Online (PAO)
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  • 1990  (24)
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  • Articles  (24)
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  • Articles: DFG German National Licenses  (24)
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  • Springer  (24)
  • American Chemical Society (ACS)
  • Nature America Inc.
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (3)
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  • 2015-2019
  • 1995-1999
  • 1990-1994  (24)
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  • 1
    Electronic Resource
    Electronic Resource
    Conservation of intron position indicates separation of major and variant H2As is an early event in the evolution of eukaryotes (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 449-455 
    Details
    ISSN: 1432-1432
    Keywords: Histone H2A ; Histone variant ; Intron position ; Drosophila ; Tetrahymena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genomic clones ofDrosophila andTetrahymena histone H2A variants were isolated using the corresponding cDNA clones, (van Daal et al. 1988; White et al. 1988). The site corresponding to the initiation of transcription was defined by primer extension for bothDrosophila andTetrahymena genomic sequences. The sequences of the genomic clones revealed the presence of introns in each of the genes. TheDrosophila gene has three introns: one immediately following the initiation codon, one between amino acids 26 and 27 (gln and phe), and one between amino acids 64 and 65 (glu and val). TheTetrahymena gene has two introns, the positions of which are identical to the first two introns of theDrosophila gene. The chicken H2A.F variant gene has been recently sequenced and it contains four introns (Dalton et al. 1989). The first three of these are in the same positions as the introns in theDrosophila gene. The fourth intron interrupts amino acid 108 (gly). In all cases the sizes and the sequences of the introns are divergent. However, the fact that they are in conserved positions suggests that at least two of the introns were present in the ancestral gene. A phylogenetic tree constructed from the sequences of the variant and major cell cycle-regulated histone H2A proteins from several species indicates that the H2A variant proteins are evolutionarily separate and distinct from the major cell cycle-regulated histone H2A proteins. The ancestral H2A gene must have duplicated and diverged before fungi and ciliates diverged from the rest of the eukaryote lineage. In addition, it appears that the variant histone H2A proteins analyzed here are more conserved than the major histone H2A proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101116
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  • 2
    Electronic Resource
    Electronic Resource
    Extreme rates and heterogeneity in insect DNA evolution (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 273-280 
    Details
    ISSN: 1432-1432
    Keywords: Genome evolution ; Molecular evolutionary rates ; Insect DNA ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary DNA-DNA hybridization studies of insects, more specificallyDrosophila and cave crickets, have revealed interesting patterns of genome evolution that contrast markedly with what has been seen in other taxa, especially mammals and birds. Insect genomes are composed of sections of single-copy DNA with extreme variation in rates of evolutionary change. This variation is more extreme than between introns and exons; introns fall into the relatively conserved fraction of the genome. Attempts to calculate absolute rates of change inDrosophila DNA have all led to estimates some 5–10 times faster than those found in most vertebrates; this is true even for the more conservative part of the nuclear genome. Finally we point out that morphological similarity, chromosomal similarity, and/or ability to form interspecific hybrids is often associated with quite high levels of single-copy DNA divergence in insects as compared to mammals and birds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02099997
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  • 3
    Electronic Resource
    Electronic Resource
    Defective ommatidial cell assembly leads to defective morphogenesis: a phenotypic analysis of the E(spl) D mutation of Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 286-294 
    Details
    ISSN: 1432-041X
    Keywords: Compound eye morphogenesis ; Enhancer of split ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The spl mutation of the N gene causes, among other phenotypic traits, the lack of a few ommatidia, roughness and a general reduction in the size of the compound eye; these defects are drastically enhanced by the dominant mutation E(spl) D. We have studied cellular and developmental aspects of the phenotypic interaction between spl and E(spl) D. We found that the initial clustering of photoreceptor cells is affected in eye imaginal discs of spl larvae causing the defects visible in the adult eye. The degree of disorganization of the spl/Y; E(spl) D/ + eye disc is much higher, only a few photoreceptor cells are able to group with representatives of the other cell types and differentiate normally. BrdU incorporation shows that the proliferation pattern of the spl/Y; E(spl) D/ + disc cells during the third instar is normal. Abundant cell death occurs posteriorly in the mutant discs, which accounts for their small size. Finally, we found that in the eye imaginal disc the transcription of m8, the E(spl) gene, responsible for the enhancement of the spl phenotype caused by the E(spl) D mutation, is restricted to the morphogenetic furrow, where the ommatidial cells start grouping with each other to take on their future developmental fates; the m8 transcription rate is highly increased in E(spl) D eye discs. All these observations indicate that the assembly of the ommatidial cells is affected in the spl/Y; E(spl) D/ + disc and that the other abnormalities are morphogenetic consequences of the defective cell grouping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377395
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  • 4
    Electronic Resource
    Electronic Resource
    Hormonally regulated expression of arginine kinase in Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 474-478 
    Details
    ISSN: 1432-041X
    Keywords: Arginine kinase ; Imaginal discs ; 20-hydroxyecdysone ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Arginine kinase (AK) is present throughout the life cycle of Drosophila melanogaster, but there is a sharp, transient peak of AK activity during the prepupal period and a second period of elevated activity at the time of eclosion of the adult. Imaginal discs show the greatest increase in AK activity at the prepupal stage of those tissues assayed. The prepupal peak is not seen when the temperature-sensitive ecdysoneless mutant ecd-1 is shifted to 29° C at mid-third instar larval stage. The peak in activity reappears when ecd-1 is either shifted back to 20° C after 60 h at 29° C or is fed 20-hydroxyecdysone. At the restrictive temperature, imaginal discs from ecd-1 larvae progressively lose AK activity, whereas discs from 20-hydroxyecdysone-fed larvae have a marked increase in AK activity at stage P3 of the prepupal period. These data suggest that the prepupal peak is regulated by the hormone 20-hydroxyecdysone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399058
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  • 5
    Electronic Resource
    Electronic Resource
    The diversity of cell morphology in cloned cell lines derived from Drosophila imaginal discs (1990)
    Springer
    Development genes and evolution 198 (1990), S. 479-482 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal disc ; Cell culture, wing ; In vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have devised a protocol for the cloning of our cell lines, and have demonstrated that a cloned line may contain cells of widely differing morphology — epithelial, fibroblast-like, and lamellocyte-like. These different morphologies must therefore represent diversity in the microenvironment of the culture rather than diversity in the cellular origin of the line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399059
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  • 6
    Electronic Resource
    Electronic Resource
    Sensitive periods for abnormal patterning on a leg segment inDrosophila melanogaster (1990)
    Springer
    Development genes and evolution 199 (1990), S. 31-47 
    Details
    ISSN: 1432-041X
    Keywords: Bristle ; Pattern formation ; Drosophila ; Gamma rays ; Mitomycin C ; Heat shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of a leg segment of the fruitflyDrosophila melanogaster was analyzed in order to determine whether the orderliness of the segment's bristle pattern originates via waves of cellular interactions, such as those that organize the retina. Fly development was perturbed at specific times by either teratogenic agents (gamma rays, heat shock, or the drug mitomycin C) or temperature-sensitive mutations (l(1)63, l(1) Notchts1, orl(1) shibire ts1 ), and the resulting abnormalities (e.g., missing or extra structures) were mapped within the pattern area. If bristles develop in a linear sequence across the pattern, then they should show sensitivity to perturbations in the same order, and wavefronts of cuticular defects should result. Contrary to this prediction, the maps reveal no evidence for any directional waves of sensitivity. Nevertheless, other clues were uncovered as to the nature and timing of patterning events. Chemosensory bristles show earlier sensitivities than mechanosensory bristles, and longer bristles precede shorter ones. The types and sequence of cuticular abnormalities imply the following stages of bristle pattern development: (1) scattered inception of bristle mother cells, each surrounded by an inhibitory field, (2) alignment of the mother cells into rows, (3) differential mitoses, (4) assignment of cuticular fates to the mitotic progeny, (5) polytenization of the bristle cells, (6) fine-tuning adjustments in bristle spacing, and (7) signalling from bristle cells to adjacent epidermal cells, inducing them to form “bracts”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01681531
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  • 7
    Electronic Resource
    Electronic Resource
    Arrangement of bristles as a function of bristle number on a leg segment inDrosophila melanogaster (1990)
    Springer
    Development genes and evolution 199 (1990), S. 48-62 
    Details
    ISSN: 1432-041X
    Keywords: Bristle ; Sensilla ; Pattern formation ; Drosophila ; achaete-scute complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The arrangement of bristles on a leg segment of the fruitflyDrosophila melanogaster was studied in various mutants that have abnormal numbers of bristles on this segment. Eighteen mutations at six different genetic loci were analyzed, plus five double or triple mutant combinations. Recessive mutations at theachaete-scute locus were found to affect distinct groups of bristles:achaete mutations remove mechanosensory bristles, whereasscute mutations remove mainly chemosensory bristles. Mechanosensory bristles remain uniformly spaced along the longitudinal axis unless their number decreases below a certain threshold, suggesting that spacing is controlled by cell interactions that cannot function when bristle cells are too far apart. Above a certain threshold, bristle spacing and alignment both become irregular, perhaps due to excessive force from these same interactions. Chemosensory bristles occupy definite positions that are virtually unaffected by removal of individual bristles from the array. Extra chemosensory bristles develop only near the six normal sites. At two of the six sites the multiple bristles tend to exhibit uniform longitudinal spacing — a property confined to mechanosensory bristles in wild-type flies. To explain the various mutant phenotypes the following scheme is proposed, with different mutations directly or indirectly affecting each step: (1) spots and stripes are demarcated within the pattern area, (2) one bristle cell normally arises within each spot, multiple bristle cells within each stripe, (3) incipient bristle cells inhibit neighboring cells from becoming bristle cells, and (4) the bristle cells within each stripe become aligned to form rows and then repel one another to generate uniform spacing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01681532
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  • 8
    Electronic Resource
    Electronic Resource
    Calcium-dependent adhesion of Drosophila embryonic cells (1990)
    Springer
    Development genes and evolution 198 (1990), S. 411-419 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Embryonic cells ; Ca2+-dependent cell aggregation ; Inhibiting antibodies ; Aggregation proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By using an in vitro functional assay, we have shown that Drosophila embryonic cells possess Ca2+-dependent adhesive sites, which resemble in many respects those described for vertebrate cells and tissues. The cells, obtained by mechanical disruption of gastrulastage embryos, form aggregates within 30 min when maintained under constant rolling. The aggregation is completely dependent on the presence of Ca2+ in the medium. In its absence, the cells remain dispersed but the process is reversible by readdition of Ca2+. In addition the aggregation is temperature-dependent. No aggregation occurs at 4° C but it can be restored by raising the temperature to 25° C. These properties are characteristic of these cells: established cell lines do not aggregate under the same conditions and mixing of cell lines and embryonic cells does not result in chimeric aggregates, thus pointing towards cell-type selectivity with respect to aggregability. Observations in electron microscopy have shown that the embryonic cells in the aggregates tightly adhere to one another and form, as early as after 30 min, maculae adherens junctions. Drosophila embryonic cells have adhesion sites that are protected from trypsin proteolysis in the presence of Ca2+ and sensitive in its absence. The cells' aggregation can be inhibited by a mouse antiserum directed against cell-surface components and a good correlation exists between neutralization of the inhibitory activity of the antiserum and the presence of trypsin-sensitive sites on the cells. These data are in favour of cell-cell adhesion mediated by specific adhesion proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376160
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  • 9
    Electronic Resource
    Electronic Resource
    Phenotypic and developmental analysis of mutations at thecrumbs locus, a gene required for the development of epithelia inDrosophila melanogaster (1990)
    Springer
    Development genes and evolution 199 (1990), S. 189-206 
    Details
    ISSN: 1432-041X
    Keywords: Crumbs ; Drosophila ; Epithelial development ; Cell death ; Cell polarity ; Non autonomous behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genecrumbs (crb) ofDrosophila melanogaster provides an essential function for the embryonic development of ectodermally derived epithelia. Complete loss of function alleles of thecrb gene are recessive embryonic lethals and lead to a disorganization of the primordia of these epithelia, followed by cell death in some tissues. Incrb mutant embryos, different organs are affected to a different extent. Some tissues die almost completely (as the epidermis, the atrium and the pharynx) while others partially survive and conserve their basic epithelial structure (as the tracheal system, the oesophagus, the proventriculus, the salivary glands, the hindgut and the Malpighian tubules). Degeneration is first visible at stage 11 and continues successively throughout development. There is evidence that the loss of epithelial cell polarity may be the cause for the degeneration of these tissues, suggesting that thecrb gene product is involved in stabilizing the apico-basal polarity of epithelial cells. As previously shown, thecrb protein is specifically expressed on the apical side of embryonic epithelia in a reticular pattern outlining the borders of the cells. Here we demonstrate that thecrb protein shows the same subcellular localization in epithelial cells of imaginal discs and in follicle cells, indicating a similar function ofcrb during the development of embryonic, imaginal and follicle epithelia. Clonal analysis experiments indicate that the genecrb is not cell-autonomous in its expression, suggesting that the gene product may act as a diffusible factor and may serve as a signal in a cell-cell communication process. This signal is thought to be required for the formation and/or maintenance of the cell and tissue structure of the respective epithelia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682078
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  • 10
    Electronic Resource
    Electronic Resource
    Asymmetrically distributed ecdysteroid-related antigens in follicles and young embryos of Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 295-302 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Oogenesis ; Embryogenesis ; Ecdysteroids ; Localized factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have produced monoclonal and polyclonal antibodies against an antigen that is asymmetrically distributed in mature oocytes of Drosophila melanogaster. During late oogenesis and early embryogenesis the antigen undergoes dramatic changes in its cellular localization: until about 2.5 h before completion of oogenesis it is homogeneously distributed in the cytoplasm, then it becomes localized in granules that are more numerous in posterior than in anterior peripheral positions of the ooplasm. The germ plasm is void of the antigen. Shortly after egg deposition the antigen is released from the granules and forms a shallow temporary gradient in the egg. Later during embryogenesis the antigen is associated with the yolk-containing cytoplasm. At the syncytial blastoderm stage it is also detected in the peripheral nuclei. Preliminary evidence suggests that the antigen is an ecdysteroid-related molecule. Five different anti-ecdysone antisera were found to bind to the same antigen or to an antigen with the same localization as our monoclonal antibody. In pattern mutants affecting anteroposterior polarity, the described asymmetrical distribution of the antigen is abnormal. In the mutant BicD, for example, which leads to the formation of two abdomina of opposite polarity, the antigen-containing granules are distributed homogeneously in mature oocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377396
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