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  • Drosophila  (44)
  • Springer  (44)
  • 1995-1999  (44)
  • 1965-1969
  • 1950-1954
  • 1995  (44)
  • 1
    Electronic Resource
    Electronic Resource
    Genetic and phenotypic variation for flight ability in the cactophilicDrosophila species,D. aldrichi andD. buzzatii (1995)
    Springer
    Entomologia experimentalis et applicata 76 (1995), S. 25-35 
    Details
    ISSN: 1570-7458
    Keywords: dispersal ; flight duration ; cactophilic ; Drosophila ; age effects ; body size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The flight ability ofDrosophila aldrichi (Patterson & Crow) andD. buzzatii (Patterson & Wheeler) using tethered flights, was measured with respect to age-related changes, genetic variation and adult body size variation induced by rearing at different larval densities.Drosophila buzzatii flew for much longer thanD. aldrichi, especially females, but age-related changes in flight duration were significant only forD. aldrichi. Effects of body size on flight ability were significant inD. buzzatii, but not inD. aldrichi. InD. buzzatii, there was a significant genotype-environment interaction (larval density × line) for flight duration, with short and average flight duration isofemale lines showing longer flights, but a long flight duration line shorter flights as body size decreased (i.e., as larval density increased). Heritability estimates for flight duration were similar in the two species, but flight duration showed no significant genetic correlations with developmental time, body size or wing dimensions (except for one wing dimension inD. buzzatii). Although not significantly different between the species, heritabilities for life-history traits (adult size and developmental time) showed contrasting patterns — with higher heritability for body size (body weight and thorax length) inD. buzzatii, and higher for developmental time inD. aldrichi. In agreement with limited previous field evidence,D. buzzatii is better adapted for colonization than isD. aldrichi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02382308
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of metallothionein genes during the post-embryonic development of Drosophila melanogaster (1995)
    Springer
    BioMetals 8 (1995), S. 339-351 
    Details
    ISSN: 1572-8773
    Keywords: metallothionein ; development ; metal induction ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Expression of the two Drosophila melanogaster metallothionein genes, Mtn and Mto, has been analyzed by in situ hybridization during post-embryonic development. Mtn and Mto transcripts were detected exclusively in the digestive tract of larvae, pupae and adults reared on standard medium. Mtn and Mto expression domains overlap, but each gene is also expressed at unique sites. Mtn mRNA levels are approximately 10 and 20 times higher than those of Mto in larvae and adults, respectively. Copper and cadmium ions strongly induce Mtn and Mto mRNA accumulation in the midgut. Zinc is a weaker inducer, acting only at high concentrations. Mtn gene expression is induced by these three metals in Malpighian tubules, while Mto gene expression in this organ is induced only by zinc. Iron is a poor inducer of metallothionein mRNA accumulation. Functions of MTN and MTO proteins in metal homeostasis and detoxification are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141608
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  • 3
    Electronic Resource
    Electronic Resource
    A method for estimating the numbers of synonymous and nonsynonymous substitutions per site (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1152-1159 
    Details
    ISSN: 1432-1432
    Keywords: Synonymous substitutions ; Nonsynonymous substitutions ; Estimation methods ; Confidence intervals ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for estimating the numbers of synonymous (Ks) and nonsynonymous (Ka) substitutions per site is proposed. The method is based on the Li's (J Mol. Evol. 36:96–99, 1993) and Pamilo and Bianchi's (Mol. Biol. Evol. 10:271–281, 1993) method, but a putative source of bias is solved. It is proposed that the number of synonymous substitutions that are actually transitions or transversions should be computed by separating the twofold degenerate sites into two types of sites, 2S-fold and 2V-fold, where only transitional and transversional substitutions are synonymous, respectively. Kimura's (J. Mol. Evol. 16:111–120, 1980) two-parameter correcting method for multiple substitutions at a site is then applied using the overall observed synonymous transversion frequency to estimate both the numbers of synonymous transversional (Bs) and transitional (As) substitutions per site. This approach, therefore, also minimizes stochastic errors. Computer simulations indicate that the method presented gives more accurate Ks and Ka estimates than the aforementioned methods. Furthermore, the obtention of confidence intervals for divergence estimates by computer simulation is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173196
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  • 4
    Electronic Resource
    Electronic Resource
    Evolution of the response patterns to dietary carbohydrates and the developmental differentiation of gene expression of α-amylase in Drosophila (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1076-1084 
    Details
    ISSN: 1432-1432
    Keywords: Evolution ; Expression patterns ; α-Amylase ; Glucose repression ; Starch induction ; Intra- and interspecific variation ; Drosophila ; Gene expression ; Regulatory genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intraspecific variation of α-amylase activity in D. melanogaster and D. immigrans, which is distantly related to D. melanogaster, and interspecific variation of α-amylase activity in 18 Drosophila species were examined. The amount of intraspecific variation of α-amylase activities measured in terms of coefficient of variation in D. melanogaster and D. immigrans was one-half and one-tenth or less, respectively, of the interspecific variation in 18 Drosophila species. We also surveyed the response patterns of α-amylase activity to dietary carbohydrates at the larval and adult stages. The levels of α-amylase activity depended on both repression by dietary glucose (glucose repression) and induction by dietary starch (starch induction). In general, our data suggest that glucose repression was conserved among species at both stages while starch induction was mainly observed in larvae, although the degree of the response depended on species. In D. lebanonensis lebanonensis and D. serrata, larvae expressed electrophoretically different α-amylase variants (isozymes) from those of adult flies. These results may suggest that the regulatory systems responsible both for the response to environment and developmental expression are different among species in Drosophila.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173189
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  • 5
    Electronic Resource
    Electronic Resource
    A Drosophila hsp70 gene contains long, antiparallel, coupled open reading frames (LAC ORFs) conserved in homologous loci (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 414-420 
    Details
    ISSN: 1432-1432
    Keywords: Gene structure ; Heat shock ; hsp70 ; Antiparallel ORFs ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A clone isolated from a Drosophila auraria heat-shock cDNA library presents two long, antiparallel, coupled (LAC) open reading frames (ORFs). One strand ORF is 1,929 nucleotides long and exhibits great identity (87.5% at the nucleotide level and 94% at the amino acid level) with the hsp70 gene copies of D. melanogaster, while the second strand ORF, in antiparallel in-frame register arrangement, is 1,839 nucleotides long and exhibits 32% identity with a putative, recently identified, NAD+-dependent glutamate dehydrogenase (NAD+-GDH). The overlap of the two ORFs is 1,824 nucleotides long. Computational analysis shows that this LAC ORF arrangement is conserved in other hsp70 loci in a wide range of organisms, raising questions about possible evolutionary benefits of such a peculiar genomic organization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160312
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  • 6
    Electronic Resource
    Electronic Resource
    High divergence of reproductive tract proteins and their association with postzygotic reproductive isolation in Drosophila melanogaster and Drosophila virilis group species (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1085-1095 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Two-dimensional electrophoresis ; Gonadal protein divergence ; Postzygotic reproductive isolation ; Speciation ; Hybrid sterility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possible association between gonadal protein divergence and postzygotic reproductive isolation was investigated among species of the Drosophila melanogaster and D. virilis groups. Protein divergence was scored by high-resolution two-dimensional electrophoresis (2DE). Close to 500 protein spots from gonadal tissues (testis and ovary) and nongonadal tissues (malpighian tubules and brain) were analyzed and protein divergence was calculated based on presence vs absence. Both testis and ovary proteins showed higher divergence than nongonadal proteins, and also a highly significant positive correlation with postzygotic reproductive isolation but a weaker correlation with prezygotic reproductive isolation. Particularly, a positive and significant correlation was found between proteins expressed in the testis and postzygotic reproductive isolation among closely related species such as the within-phylad species in the D. virilis group. The high levels of male-reproductive-tract protein divergence between species might be associated with F1 hybrid male sterility among closely related species. If so, a lower level of ovary protein divergence should be expected on the basis that F1 female hybrids are fully fertile. However, this is not necessarily true if relatively few genes are responsible for the reproductive isolation observed between closely related species, as recent studies seem to suggest. We suggest that the faster rate of evolution of gonadal proteins in comparison to nongonadal proteins and the association of that rate with postzygotic reproductive isolation may be the result of episodic and/or sexual selection on male and female molecular traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173190
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  • 7
    Electronic Resource
    Electronic Resource
    Structural evolution of the Drosophila 5S ribosomal genes (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 615-621 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Ribosomal genes ; Sequence data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compare the 5S gene structure from nine Drosophila species. New sequence data (5S genes of D. melanogaster, D. mauritiana, D. sechellia, D. yakuba, D. erecta, D. orena, and D. takahashii) and already-published data (5S genes of D. melanogaster, D. simulans, and D. teissieri) are used in these comparisons. We show that four regions within the Drosophila 5S genes display distinct rates of evolution: the coding region (120 bp), the 5′-flanking region (54–55 bp), the 3′-flanking region (21–22 bp), and the internal spacer (149–206 bp). Intra- and interspecific heterogeneity is due mainly to insertions and deletions of 6–17-bp oligomers. These small rearrangements could be generated by fork slippages during replication and could produce rapid sequence divergence in a limited number of steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175820
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  • 8
    Electronic Resource
    Electronic Resource
    Flight initiations in Drosophila melanogaster are mediated by several distinct motor patterns (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 355-364 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Giant fiber ; Escape Olfactory ; Flight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have monitored the patterns of activation of five muscles during flight initiation of Drosophila melanogaster: the tergotrochanteral muscle (a mesothoracic leg extensor), dorsal longitudinal muscles #3, #4 and #6 (wing depressors), and dorsal ventral muscle #Ic (a wing elevator). Stimulation of a pair of large descending interneurons, the giant fibers, activates these muscles in a stereotypic pattern and is thought to evoke escape flight initiation. To investigate the role of the giant fibers in coordinating flight initiation, we have compared the patterns of muscle activation evoked by giant fiber stimulation with those during flight initiations executed voluntarily and evoked by visual and olfactory stimuli. Visually elicited flight initiations exhibit patterns of muscle activation indistinguishable from those evoked by giant fiber stimulation. Olfactory-induced flight initiations exhibit patterns of muscle activation similar to those during voluntary flight initiations. Yet only some benzaldehyde-induced and voluntary flight initiations exhibit patterns of muscle activation similar to those evoked by giant fiber stimulation. These results indicate that visually elicited flight initiations are coordinated by the giant fiber circuit. By contrast, the giant fiber circuit alone cannot account for the patterns of muscle activation observed during the majority of olfactory-induced and voluntary flight initiations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219061
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  • 9
    Electronic Resource
    Electronic Resource
    Properties of histamine-activated chloride channels in the large monopolar cells of the dipteran compound eye: a comparative study (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 611-623 
    Details
    ISSN: 1432-1351
    Keywords: Ligand-gated channel ; Chloride channel ; Histamine ; Drosophila ; Visual ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The large monopolar cells (LMCs) of the first optic neuropil (lamina) in insects respond to the photoreceptor neurotransmitter histamine with an increase in chloride conductance. We have compared the properties of this conductance from a range of diptera from different visual environments: Tipula paludosa (slow flying, crepuscular), Drosophila melanogaster (slow-flying diurnal), and 3 fast-flying diurnal species Musca domestica, Calliphora vicina and Lucilia sericata. In whole-cell recordings of dissociated LMCs, histamine-induced currents were elicited using a multichannel parallel perfusion device, allowing rapid determination of the dose-response function, characterised by affinity (K d) and Hill coefficient (n). Calliphora, Lucilia and Musca had the steepest dose response curves (n = 2.8) and the lowest affinity for histamine (K d 35–50 μM); the crepuscular Tipula had a significantly higher affinity (K d = 16 μM) and lower Hill coefficient (n = 1.8). Drosophila had a high affinity (K d 24 μM), and a high Hill coefficient (n = 2.5). In excised inside-out patch recordings all species showed similar single channel properties (conductance 40–60 pS, mean open time 〈 1 ms). The low Hill coefficient in Tipula would be expected to result in lower synaptic gain. We suggest this may be an adaptation to prevent the LMC's response bandwidth being filled with the high levels of photon noise typical of photoreceptors adapted for low light levels. The lower affinity for histamine found in the more photopic species suggests that the concentration of histamine (and therefore presumably number of synaptic vesicles released from the photoreceptors) should be higher. This might improve signal-to-noise ratio by decreasing the contribution of the shot event noise introduced by stochastic release of synaptic vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192490
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  • 10
    Electronic Resource
    Electronic Resource
    Properties of histamine-activated chloride channels in the large monopolar cells of the dipteran compound eye: a comparative study (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 611-623 
    Details
    ISSN: 1432-1351
    Keywords: Ligand-gated channel ; Chloride channel ; Histamine ; Drosophila ; Visual ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The large monopolar cells (LMCs) of the first optic neuropil (lamina) in insects respond to the photoreceptor neurotransmitter histamine with an increase in chloride conductance. We have compared the properties of this conductance from a range of diptera from different visual environments:Tipula paludosa (slow flying, crepuscular),Drosophila melanogaster (slow-flying diurnal), and 3 fast-flying diurnal speciesMusca domestica,Calliphora vicina andLucilia sericata. In whole-cell recordings of dissociated LMCs, histamine-induced currents were elicited using a multichannel parallel perfusion device, allowing rapid determination of the dose-response function, characterised by affinity (K d) and Hill coefficient (n).Calliphora,Lucilia andMusca had the steepest dose response curves (n = 2.8) and the lowest affinity for histamine (K d 35–50 μM); the crepuscularTipula had a significantly higher affinity (K d = 16 μM) and lower Hill coefficient (n = 1.8).Drosophila had a high affinity (K d 24 μM), and a high Hill coefficient (n = 2.5). In excised inside-out patch recordings all species showed similar single channel properties (conductance 40–60 pS, mean open time 〈 1 ms). The low Hill coefficient inTipula would be expected to result in lower synaptic gain. We suggest this may be an adaptation to prevent the LMC's response bandwidth being filled with the high levels of photon noise typical of photoreceptors adapted for low light levels. The lower affinity for histamine found in the more photopic species suggests that the concentration of histamine (and therefore presumably number of synaptic vesicles released from the photoreceptors) should be higher. This might improve signal-to-noise ratio by decreasing the contribution of the shot event noise introduced by stochastic release of synaptic vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021581
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  • 11
    Electronic Resource
    Electronic Resource
    Analysis of neural elements in head-mutant Drosophila embryos suggests segmental origin of the optic lobes (1995)
    Springer
    Development genes and evolution 205 (1995), S. 31-44 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Head development ; Segmentation mutants ; Nervous system ; Optic lobe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We describe the development of 20 sensory organs in the embryonic Drosophila head, which give rise to 7 sensory nerves of the peripheral nervous system (PNS), and 4 ganglia of the stomatogastric nervous system (SNS). Using these neural elements and the optic lobes as well as expression domains of the segment polarity gene engrailed in the wild-type head of Drosophila embryos as markers we examined the phenotype of different mutants which lack various and distinct portions of the embryonic head. In the mutants, distinct neural elements and engrailed expression domains, serving as segmental markers, are deleted. These mutants also affect the optic lobes to various degrees. Our results suggest that the optic lobes are of segmental origin and that they derive from the ocular segment anteriorly adjacent to the antennal segment of the developing head.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188841
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  • 12
    Electronic Resource
    Electronic Resource
    Morphogenesis and cellular proliferation pattern in the developing antennal lobe of Drosophila melanogaster (1995)
    Springer
    Development genes and evolution 205 (1995), S. 62-72 
    Details
    ISSN: 1432-041X
    Keywords: Antennal lobe ; Cell division ; euroblasts ; BrdU incorporation ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The adult antennal lobe of Drosophila melanogaster emerges from a precursor, the larval antennal lobe. Pulse and pulse-chase labelling of dividing cells in larvae and pupae with bromodeoxyuridine confirmed previous data that some of the interneurons of the adult antennal lobe derive from a lateral neuroblast which starts to divide early in the first larval instar. However, the majority of these interneurons originate from neuroblasts that initiate mitosis at later stages, with a peak of about 10–12 pairs of dividing neuroblasts in the late third larval instar. No clustering of adult antennal lobe neurons according to their birthdates was observed. In contrast to neurons, terminal divisions of glia in the antennal lobe reach their maximum only 12 h after puparium formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188844
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  • 13
    Electronic Resource
    Electronic Resource
    aproctous, a locus that is necessary for the development of the proctodeum in Drosophila embryos, encodes a homolog of the vertebrate Brachyury gene (1995)
    Springer
    Development genes and evolution 205 (1995), S. 89-96 
    Details
    ISSN: 1432-041X
    Keywords: Brachyury ; Trg ; Hindgut ; Proctodeum ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The proctodeum of the Drosophila embryo originates from the posterior end of the blastoderm and forms the hindgut. By enhancer-trap mutagenesis, using a P-element-lacZ vector, we identified a mutation that caused degeneration of the proctodeum during shortening of the germ band and named it aproctous (apro). Expression of the lacZ reporter gene, which was assumed to represent expression of the apro gene, began at the cellular blastoderm stage in a ring that encompassed about 10–15% of the egg's length (EL) and included the future proctodeum, anal pads, and posterior-most part of the visceral mesoderm. In later stages, strong expression of lacZ was detected in the developing hindgut and anal pads. Expression continued in the anal pads and epithelium of the hindgut of larvae; the epithelium of the hindgut of the adult fly also expressed lacZ. The spatial patterns of the expression of lacZ in various mutants suggested that the embryonic expression of apro was regulated predominantly by two gap genes, tailless (tll) and huckebein (hkb): tll is necessary for the activation of apro, while hkb suppressed the expression of apro in the region posterior to 10% EL. Cloning and sequencing of the apro cDNA revealed that apro was identical to the T-related gene (Trg) that is a Drosophila homolog of the vertebrate Brachyury gene. apro appears to play a key role in the development of tissues derived from the proctodeum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188847
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  • 14
    Electronic Resource
    Electronic Resource
    Search for Drosophila genes based on patterned expression of mini-white reporter gene of a P lacW vector in adult eyes (1995)
    Springer
    Development genes and evolution 205 (1995), S. 114-121 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Mini-white reporter gene ; Teashirt ; Engrailed ; Wingless
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Developmental expression of transduced mini-white(w) gene of Drosophila is sensitive to its flanking genomic enhancers. Taking advantage of this phenomenon, we mobilized a P lacW transposon and screened for new transposant lines which showed patterned expression of the mini-w gene in adult eyes. From a screen of about 1,000 independent P lacW transposant lines on the second chromosome, we identified 7 lines which showed patterned w expression in adult eyes. These P insertions were assigned to engrailed, wingless and teashirt genes based on their chromosomal locations, developmental expression of the lacZ reporter gene, lethal embryonic mutant phenotypes and, finally, their failure to complement the lethal alleles of the respective genetic loci. Our results show that although only a small fraction of the total transposant lines displayed patterned w expression, the genetic loci thus identified are those which play essential roles in pattern formation. Scopes of screens for genetic loci based on w reporter gene expression in adult eyes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357757
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  • 15
    Electronic Resource
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    Mutations in neuromusculin, a gene encoding a cell adhesion molecule, cause nervous system defects (1995)
    Springer
    Development genes and evolution 204 (1995), S. 259-270 
    Details
    ISSN: 1432-041X
    Keywords: Ig-like domains ; Cell adhesion ; Peripheral and central nervous system ; Muscles ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila neuromusculin (nrm) gene encodes an immunoglobulin-like (Ig-like) cell adhesion molecule expressed in the precursors of the embryonic peripheral nervous system (PNS), in the midline precursors of the central nervous system (CNS), and in muscles. During the initial phases of CNS axonogenesis, nrm is expressed in cells involved in the development of commissures and longitudinal tracts. Mutations which alter expression of nrm mRNAs cause aberrant development of commissures and longitudinal axon pathways. Defects in the PNS and muscles of nrm mutants are also observed. In most nrm embryos, abnormal development can be detected in a subset of abdominal segments; however, in approximately 1 of 10 nrm embryos, the defects extend to all segments. Herein, we present evidence that nrm plays an important role in early morphogenesis, possibly by mediating or facilitating inductive cell contacts and movements.
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    URL: http://dx.doi.org/10.1007/BF00208493
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  • 16
    Electronic Resource
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    Distribution, classification, and development ofDrosophila glial cells in the late embryonic and early larval ventral nerve cord (1995)
    Springer
    Development genes and evolution 204 (1995), S. 284-307 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Central nervous system ; Glia GAL4 enhancer trap ; Classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To facilitate the investigation of glial development inDrosophila, we present a detailed description of theDrosophila glial cells in the ventral nerve cord. A GAL4 enhancer-trap screen for glial-specific expression was performed. Using UAS-lacZ and UAS-kinesin-lacZ as reporter constructs, we describe the distribution and morphology of the identified glial cells in the fully differentiated ventral nerve cord of first-instar larvae just after hatching. The three-dimensional structure of the glial network was reconstructed using a computer. Using the strains with consistent GAL4 expression during late embryogenesis, we traced back the development of the identified cells to provide a glial map at embryonic stage 16. We identify typically 60 (54–64) glial cells per abdominal neuromere both in embryos and early larvae. They are divided into six subtypes under three categories: surface-associated glia (16–18 subperineurial glial cells and 6–8 channel glial cells), cortex-associated glia (6–8 cell body glial cells), and neuropile-associated glia (8–10 nerve root glial cells, 14–16 interface glial cells, and 3–4 midline glial cells). The proposed glial classification system is discussed in comparison with previous insect glial classifications.
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    URL: http://dx.doi.org/10.1007/BF02179499
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  • 17
    Electronic Resource
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    Contribution of the geneextramacrochaetae to the precise positioning of bristles inDrosophila (1995)
    Springer
    Development genes and evolution 204 (1995), S. 336-343 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Extramacrochaetae ; Pattern formation ; Sensory bristle positioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examine the effect of mutations in theextramacrochaetae (emc) gene on the positioning of macrochaetes on the notum ofDrosophila. We show that, inemc mutants, most of the precursor cells appear earlier than in wild-type individuals, consistent with an antagonizing effect ofemc on the action of the proneural genesachaete andscute. We also show that reducingemc function affects the position of three bristles and/or of their precursors, but has no marked effect on the positioning of the other bristles.
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    URL: http://dx.doi.org/10.1007/BF02179502
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  • 18
    Electronic Resource
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    Defects in the adult abdominal integument ofDrosophila caused by mutations intorpedo, a DER homolog (1995)
    Springer
    Development genes and evolution 204 (1995), S. 330-335 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; top mutation ; DER gene ; Histoblast nests ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheDrosophila homolog of the vertebrate EGF receptor (DER) gene is encoded by thetorpedo (top) locus. We examined the role oftop in the development and differentiation of the integument of the adult abdomen ofDrosophila, by analysing these processes in transheterozygotes of twotop alleles. The mutation, when compared to the wild type, affected mitosis, spreading and differentiation of adult epidermal cells derived from the various histoblast and spiracular nests. Our observations indicate that the need for wild-typetop gene product becomes critical after pupation, and the requirement continues throughout the rest of adult development for the normal morphogenesis of the abdominal integument and spiracles.
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    URL: http://dx.doi.org/10.1007/BF02179501
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  • 19
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    The effects of the glucocorticoid, dexamethasone, on the development of the Drosophila embryo (1995)
    Springer
    Development genes and evolution 204 (1995), S. 359-368 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Steroids ; Glucocorticoids ; Embryogenesis ; Amnioserosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the effects of the glucocorticoid, dexamethasone, and five structural analogs on Drosophila development in an effort to identify steroid ligands that may play a role in the embryogenesis of this organism. Embryos were exposed to glucocorticoids either by direct culture in supplemented medium, or by examining embryos from adult flies raised on supplemented fly food. After exposure, embryos were examined for developmental defects. At a morphological level, exposure to dexamethasone disrupts the dorsolateral folding of the amnioserosa during germ band extension. In addition, germ band retraction and dorsal closure is also disrupted. The phenocritical period of these effects is within the first 4 h of embryogenesis. This response is dosage sensitive, with embryos responding to concentrations of dexamethasone ranging from 10−6 to 10−3M. Furthermore, glucocorticoids which are closely related structural analogs of dexamethasone also disrupt germ band retraction and dorsal closure, while other tested steroids had no effect on embryonic development. At a molecular level, expression of the gene, Krüppel, is absent from the amnioserosa of dexamethasone-treated embryos. The cuticular phenocopy resulting from exposure to dexamethasone and related glucocorticoids is morphologically similar to the mutant phenotype associated with four genes required for germ band retraction, namely hindsight, serpent, tail-up and u-shaped. The results of this study represent the first association of a glucocorticoid with dose, stage and tissue specific effects on Drosophila development at both morphological and molecular levels.
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    URL: http://dx.doi.org/10.1007/BF00360481
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    Enhancer-trap detection of expression patterns corresponding to the polar coordinate system in the imaginal discs of Drosophila melanogaster (1995)
    Springer
    Development genes and evolution 204 (1995), S. 378-391 
    Details
    ISSN: 1432-041X
    Keywords: Positional information ; Polar coordinate model ; Enhancer trap ; Imaginal disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated three classes of “enhancertrap” lines of Drosophila in which lacZ expression patterns in the imaginal discs are consistent with the idea of a polar (radial and angular) coordinate system of positional information. In the first class (HZ76), a circular pattern was expressed transiently during the mid-third instar larval stage when the radial components of the coordinate are probably generated. The expression patterns of the second class (HZ84) were sector-shaped and circular in the leg disc, suggesting a correlation with both radial and angular coordinate values. The expression patterns found in the third class (PZ63 and PZ22) were circular and appeared to reflect radial positional values. Expression in the latter two classes always began in the presumptive dorsal region of the leg disc and gradually spread to the ventral region. These developmental profiles of expression suggested the existence of a centre that initiates patterned gene expression in the presumptive dorsal region of the leg disc. The PZ22 line showed transient expression during tarsal segmentation, suggesting its involvement in tarsal segment formation. We have cloned the PZ22 gene and partially determined its sequence. The deduced amino acid sequence contained a zinc finger motif found in DNA/RNA binding proteins. By in situ hybridization, we determined that the PZ22 gene was transcribed in the leg disc in a pattern identical to that of the lacZ expression. In addition, it was expressed transiently in the embryonic mesoderm during mesoderm segmentation. The PZ22 gene, therefore, may function both in mesodermal segmentation in the embryo and in tarsal segmentation in the imaginal disc.
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    URL: http://dx.doi.org/10.1007/BF00360483
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    Structure and regulation of the fushi tarazu gene from Drosophila hydei (1995)
    Springer
    Development genes and evolution 205 (1995), S. 160-170 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Evolution ; fz ; Homeodomain ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila melanogaster segmentation gene fushi tarazu (ftz) encodes a homeodomain-type transcription factor involved in the control of larval pattern formation. Loss of function mutations cause an embryonic lethal, pair-rule phenotype. The segmentation defects, but not the lethality, can be partially rescued by the ftz orthologue from Drosophila hydei. In this work, the primary structure, expression and regulation of the D. hydei ftz gene was characterized. Sequence comparisons classify ftz as a rather fast evolving gene. However, since the homeodomain of the D. hydei FTZ protein is highly similar to that of D. melanogaster, proper regulation of D. melanogaster ftz downstream genes would be expected. In D. melanogaster embryos, a D. hydei ftz transgene is expressed normally, independent of endogenous ftz gene activity, suggesting that D. hydei ftz regulatory sequences are correctly recognized by D. melanogaster transcription factors. Accordingly, lacZ fusion constructs driven by the D. hydei ftz upstream element are expressed normally in D. melanogaster embryos. Altogether, the similarities between the two ftz orthologues by far outweigh the differences. The limited success of the trans-species rescue might be, therefore, a consequence of the accumulation of too many subtle changes in gene function, exceeding the limits of developmental plasticity during fly embryogenesis.
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    URL: http://dx.doi.org/10.1007/BF00357762
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    Physiological genetics of the response to a high-sucrose diet byDrosophila melanogaster (1995)
    Springer
    Biochemical genetics 33 (1995), S. 149-165 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; metabolic regulation ; selection ; diet ; induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A diet medium containing 10% (w/v) sucrose can be inferred to be stressful toDrosophila melanogaster from the increased developmental time and reduced size and fecundity of emerging flies. The metabolic basis for this stress and the genetic response to it are of interest from the point of view of both metabolic regulation and the evolutionary genetics of adaptation to stress. Here the effects of a high-sucrose diet on live weight, total protein, stored lipid and glycogen, and crude activities of 12 enzymes involved in energy metabolism were quantified. Assays were done on a large population ofDrosophila that had been acclimated to the laboratory. A collection of eggs was divided to produce two replicate populations maintained on standard medium and two replicates maintained on high-sucrose medium for 133 generations. At the end of this period, both control and sucrose-selected populations were tested on standard and on high-sucrose medium. Results showed that the immediate effect of the high-sucrose diet (compared to standard medium) for both populations was a reduction in live weight and total protein, and activities of many of the enzymes were also reduced by the sucrose treatment, even after adjusting for the weight effect. Selection resulted in several changes on both the standard and the sucrose medium, but the direction of change was not always the same as the acute effect. In no case was there a significant medium by selection-treatment interaction. The pattern of phenotypic correlations did not resolve the reasons for the direction of the genetic responses. Correlations were generally stable across diets and after selection, but there were notable exceptions.
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    Evolution of the noncoding regions inDrosophila mitochondrial DNA: Two intergenic regions (1995)
    Springer
    Biochemical genetics 33 (1995), S. 73-82 
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    ISSN: 1573-4927
    Keywords: mitochondrial DNA ; Drosophila ; noncoding intergenic region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The sequences of the mitochondrial DNA (mtDNA) segment containing the two intergenic regions were determined for six species belonging to theDrosophila immigrans species group and compared to the corresponding segments ofDrosophila species which had been studied previously. We found remarkable differences in the evolutionary rates of the two intergenic regions. The Intergenic I region, which lies between thetRNA gln and thetRNA ile genes, was found to be highly conserved in terms of both size (30 ntp) and nucleotide sequence among the species studied. In contrast, the sequences of the Intergenic II region, which lies between thetRNA f-met and thetRNA ile genes, showed considerable variation. The size of the Intergenic II region ranged from 0 to 88 ntp, and accurate alignment was possible only among sequences from geographical strains or very closely related species in thenasuta species subgroup. The observed differences in conservation of the two mtDNA intergenic regions are discussed in light of functional constraints on mtDNA sequences.
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    RNase P as hyperprocessing enzyme: A model for formation of a biologically functional tRNA fragment (1995)
    Springer
    Molecular biology reports 22 (1995), S. 171-175 
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    ISSN: 1573-4978
    Keywords: Drosophila ; hyperprocessing ; primer ; retrotransposoncopia ; reverse transcription ; RNA processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hyperprocessing is defined as a further processing of mature RNA that produces another functional RNA. Hyperprocessing occurs inDrosophila cells. In the transposoncopia-related retrovirus-like particles ofDrosophila, a 39-nucleotide-long fragment from the 5′-region ofDrosophila initiator methionine tRNA is used as the primer forcopia minus-strand reverse transcription. This primer tRNA fragment is thought to be produced by cleavage within the mature tRNA sequence. We found that the catalytic RNA subunit of RNase P catalyzes this hyperprocessingin vitro and that this cleavage is dependent of the occurrence of an altered conformation of the tRNA substrate. In this review, I will summarize our work from the finding of the functional RNA fragment to the finding of a dynamic tRNA structure
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    Progress inDrosophila genome manipulation (1995)
    Springer
    Transgenic research 4 (1995), S. 155-162 
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    ISSN: 1573-9368
    Keywords: Drosophila ; transposon ; P element ; enhancer-trap ; FLP/FRT ; reverse genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The introduction of cloned and manipulated genetic material into the germline of an experimental organism is one of the most powerful tools of modern biology. In the case of the fruit fly,Drosophila melanogaster, there is also an unparalleled range of sophisticated genetic tools to facilitate subsequent analysis. In consequence,Drosophila remains a most favourable model organism for the dissection of gene structure and functionin vivo. In this review we look at some of the achievements to date inDrosophila genome manipulation, and at what may be possible in the near future.
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    Defective I elements introduced intoDrosophila as transgenes can regulate reactivity and prevent I-R hybrid dysgenesis (1995)
    Springer
    Molecular genetics and genomics 248 (1995), S. 381-390 
    Details
    ISSN: 1617-4623
    Keywords: Hybrid dysgenesis ; Reactivity ; I element ; LINE ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The I-R hybrid dysgenesis syndrome is characterized by a high level of sterility and I element transposition, occurring in the female offspring of crosses between males of inducer (I) strains, which contain full-length transposable I elements, and females of reactive (R) strains, devoid of functional I elements. The intensity of the syndrome in the dysgenic cross is essentially dependent on the reactivity level of the R females, which is ultimately controlled by still unresolved polygenic chromosomal determinants. In the work reported here, we have introduced a transposition-defective I element with a 2.6 kb deletion within its second open reading frame into a highly reactive R strain, by P-mediated transgenesis. We demonstrate that this defective I element gradually alters the level of reactivity in the three independent transgenic lines that were obtained, over several generations. After 〉 15 generations, the transgenicDrosophila show strongly reduced reactivity, and finally become refractory to hybrid dysgenesis, without, however, acquiring the inducer phenotype. Induction of a low reactivity level is reversible reactivity again increases upon transgene removal and is maternally inherited, as observed for the control of reactivity in natural R strains. These results demonstrate that defective I elements introduced as single-copy transgenes can act as regulators of reactivity, and suggest that some of the ancestral defective pericentromeric I elements that can be found in all reactive strains could be the molecular determinants of reactivity.
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    URL: http://dx.doi.org/10.1007/BF02191637
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    Characterization ofGandalf, a new inverted-repeat transposable element ofDrosophila koepferae (1995)
    Springer
    Molecular genetics and genomics 248 (1995), S. 423-433 
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    ISSN: 1617-4623
    Keywords: Drosophila ; Transposable elements ; repleta group ; Ac family ; Hybrid instability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cloning and characterization ofGandalf, a new DNA-transposing mobile element obtained from theDrosophila koepferae (repleta group) genome is described. A fragment ofGandalf was found in a middle repetitive clone that shows variable chromosomal localization. Restriction, Southern blot, PCR and sequencing analyses have shown that mostGandalf copies are about 1 kb long, are flanked by 12 by inverted terminal repeats and contain subterminal repetitive regions on both sides of the element. As with other elements of the DNA-transposing type (known as the ‘Ac family’), theGandalf element generates 8 by direct duplications at the insertion point. Coding region analysis has shown that the longer open reading frame found inGandalf copies could encode part of a protein. However, whether or not the 1 kb copies of the element are actually the active transposons remains to be elucidated.Gandalf shows a very low copy number inD. buzzatii, a sibling species ofD. koepferae. An attempt to induce interspecific hybrid dysgenesis in hybrids of these two species has been unsuccessful.
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    Evolution of the LINE-like I element in the Drosophila melanogaster species subgroup (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 168-178 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; I element ; Retrotransposon ; Horizontal transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract LINE-like retrotransposons, the so-called I elements, control the system of I-R (inducer-reactive) hybrid dysgenesis in Drosophila melanogaster. I elements are present in many Drosophila species. It has been suggested that active, complete I elements, located at different sites on the chromosomes, invaded natural populations of D. melanogaster recently (1920–1970). But old strains lacking active I elements have only defective I elements located in the chromocenter. We have cloned I elements from D. melanogaster and the melanogaster subgroup. In D. melanogaster, the nucleotide sequences of chromocentral I elements differed from those on chromosome arms by as much as 7%. All the I elements of D. mauritiana and D. sechellia are more closely related to the chromosomal I elements of D. melanogaster than to the chromocentral I elements in any species. No sequence difference was observed in the surveyed region between two chromosomal I elements isolated from D. melanogaster and one from D. simulans. These findings strongly support the idea that the defective chromocentral I elements of D. melanogaster originated before the species diverged and the chromosomal I elements were eliminated. The chromosomal I elements reinvaded natural populations of D. melanogaster recently, and were possibly introduced from D. simulans by horizontal transmission.
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    Aggregation and the maintenance of genetic diversity: An individual-based cellular model (1995)
    Springer
    Evolutionary ecology 9 (1995), S. 508-519 
    Details
    ISSN: 1573-8477
    Keywords: aggregation ; polymorphism ; Drosophila ; patches ; soft-selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A cellular model, where each individual is explicitly defined, is used to describe a population of a mycophagous species ofDrosophila. Patches represent single fungal fruiting bodies which are only available as oviposition sites for a single fly generation. Standard competition equations are used to describe the interaction between larval genotypes at each patch. Dispersal of adults is obligatory and uses a simple model of patch choice to produce aggregated arrivals of adults at fresh patches. The degree to which aggregation of adults and eggs can promote coexistence of genotypes in a one-locus, two-allele system with dominance is explored. When both phenotypes (A- andaa) are aggregated, a polymorphism can be maintained for over 1000 generations even when the selective disadvantage of one phenotype (aa) is great. This model enhances the degree of polymorphism in a population, using aggregation. It does not preclude the operation of other methods which enhance the coexistence of genotypes. Therefore, it is acting to augment the degree of polymorphism maintained in species which exploit patchy and ephemeral habitats, including allDrosophila and a wide range of other organisms.
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    Expression of the dihydroorotate dehydrogenase gene, dhod, during spermatogenesis in Drosophila melanogaster (1995)
    Springer
    Molecular genetics and genomics 246 (1995), S. 334-341 
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    ISSN: 1617-4623
    Keywords: Spermatogenesis ; Transcriptional regulation ; Translational regulation ; Pyrimidine biosynthesis ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dhod gene encodes dihydroorotate dehydrogenase (DHOdehase), which catalyzes the fourth step of de novo pyrimidine biosynthesis. In addition to the common 1.5 kb dhod RNA expressed by embryos and females, adult males produce a group of slightly longer RNAs. Evidence is presented that the latter RNAs arise through transcription initiation at sites upstream from that of the common RNA and expression of these male-specific RNAs is limited to spermatogenesis. In situ hybridization analysis shows that these RNAs accumulate during spermatocyte growth and persist through meiosis and early spermatid differentiation. In contrast, DHOdehase activity is virtually absent in spermatocytes, meiotic cells, and in early spermatid cysts, then it becomes highly abundant in elongated spermatid cysts and disappears in late spermatogenesis. Thus, testis-limited expression of dhod conforms to a model proposed for other genes that function during spermiogenesis : transcription in spermatocytes, storage of translationally inactive RNA through meiosis, translation of the RNA during spermiogenesis. Very similar expression of a testis promoter-lacZ fusion transgene indicates that sequences required for the spermatogenesis transcription and translation patterns are confined to the 5′ end of the dhod gene. Deletion analysis of that 5′ region delimits all sequences necessary for spermatid expression of the transgene to a 89 by fragment. These results are discussed in the contexts of known mechanisms of gene regulation during spermatogenesis and potential roles of DHOdehase during spermiogenesis.
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    Theraspberry locus encodesDrosophila inosine monophosphate dehydrogenase (1995)
    Springer
    Molecular genetics and genomics 248 (1995), S. 755-766 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Inosine monophosphate dehydrogenase ; Guanine nucleotide metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Investigation of an enhancer-trap line exhibiting testis-specificβ-galactosidase expression led to the isolation of theDrosophila gene encoding inosine monophosphate dehydrogenase (IMPD), the rate-limiting enzyme in guanine nucleotide synthesis, which has been implicated in cell cycle control and malignant transformation. Northern and in situ hybridization analysis demonstrated that the gene has a complex expression pattern involving several independently regulated transcripts. Two ubiquitous, but highly ovary enriched, transcripts of 2.5 and 1.9 kb are expressed in the nurse cells and delivered to the oocyte, whilst a 0.9 kb transcript is found exclusively in the testis. The 2.5 kb transcript encodes a 58 kDa protein, which is highly similar in length and sequence to mouse and human IMPDs and is presumably required for GTP synthesis during early embryogenesis. Over-expression of this cDNA inEscherichia coli yielded a product of the predicted size, which was demonstrated to possess IMPD activity in a spectrophotometric assay. The coding capacity of the other transcripts is currently uncertain. We present evidence that IMPD is the product of theraspberry (ras) locus at 9E and the functions of the gene are discussed in relation to the phenotypes ofras mutants.
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    Functional analysis of theDrosophila CDC2 Dm gene in fission yeast (1995)
    Springer
    Molecular genetics and genomics 248 (1995), S. 621-628 
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    ISSN: 1617-4623
    Keywords: Drosophila ; CDC2 ; Fission yeast ; Cell cycle ; UV hypersensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thecdc2 + gene product (p34cdc2) is a protein kinase that regulates entry into mitosis in all eukaryotic cells. The role that p34cdc2 plays in the cell cycle has been extensively investigated in a number of organisms, including the fission yeastSchizosaccharomyces pombe. To study the degree of functional conservation among evolutionarily distant p34cdc2 proteins, we have constructed aS. pombe strain in which the yeastcdc2 + gene has been replaced by itsDrosophila homologue CDC2Dm (theCDC2Dm strain). ThisCDC2Dm S. pombe strain is viable, capable of mating and producing four viable meiotic products, indicating that the fly p34CDC2Dm recognizes all the essentialS. pombe cdc2 + substrates, and that it is recognized by cyclin partners and other elements required for its activity. The p34CDC2Dm protein yields a lethal phenotype in combination with the mutant B-type cyclin p56cdc13-117, suggesting that thisS. pombe cyclin might interact less efficiently with theDrosophila protein than with its native p34cdc2 counterpart. ThisCDC2Dm strain also responds to nutritional starvation and to incomplete DNA synthesis, indicating that proteins involved in these signal transduction pathways, interact properly with p34CDC2Dm (and/or that p34cdc2-independent pathways are used). TheCDC2Dm gene produces a ‘wee’ phenotype, and it is largely insensitive to the action of theS. pombe weel + mitotic inhibitor, suggesting thatDrosophila weel + homologue might not be functionally conserved. ThisCDC2Dm strain is hypersensitive to UV irradiation, to the same degree asweel-deficient mutants. A strain which co-expresses theDrosophila and yeastcdc2+ genes shows a dominantwee phenotype, but displays a wild-type sensitivity to UV irradiation, suggesting that p34cdc2 triggers mitosis and influences the UV sensitivity by independent mechanisms.
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    Separate cis-regulatory sequences control expression of serendipity β and janus A, two immediately adjacent Drosophila genes (1995)
    Springer
    Molecular genetics and genomics 246 (1995), S. 549-560 
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    ISSN: 1617-4623
    Keywords: Drosophila ; janus A ; serendipity β cis-regulatory elements ; Gene cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genes janus (Jan) A and B, and serendipity (sry) β and λ are two pairs of duplicated genes that are adjacent to each other on the third chromosome of Drosophila melanogaster. The jan A and sry β genes are expressed throughout development in both males and females. They are transcribed in opposite orientations from start sites separated by only 173 by of DNA. We report here the complete sequence of the jan A and B genes in Drosophila pseudoobscura, a species distantly related to D. melanogaster in which the overall organization of the sry β, Jan A and jan B genes is identical to that in D. melanogaster. Sequence comparison of the jan A-sry β intergenic region and 5'-transcribed domain of each gene between D. melanogaster and D. pseudoobscura reveals short stretches of conserved sequences that may correspond to cis-acting regulator elements. In order to test the possibility that some cis-acting regulatory sequences are shared by the two genes, we carried out a deletion analysis of the jan A/sry β intergenic region in D. melanogaster using transgenic lacZ fusion genes. Our results show that sry β cis-acting sequences are located in the (-117; + 137) 5′-region of the gene and that jan A cis-regulatory sequences are included in the (-56; +151) 5′-domain of this gene. Together these data indicate that in spite of the physical proximity of the jan A and sry β genes, their transcription is regulated by separate cis-acting sequences.
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    The distribution of the transposable elementBari-1 in theDrosophila melanogaster andDrosophila simulans genomes (1995)
    Springer
    Genetica 96 (1995), S. 269-283 
    Details
    ISSN: 1573-6857
    Keywords: Bari-1 ; Drosophila ; genomic organization ; transposons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of the transposable elementBari-1 inD. melanogaster andD. simulans was examined by Southern blot analysis and byin situ hybridization in a large number of strains of different geographical origins and established at different times.Bari-1 copies mostly homogeneous in size and physical map are detected in all strains tested. Both inD. melanogaster and inD. simulans a relatively high level of intraspecific insertion site polymorphism is detectable, suggesting that in both speciesBari-1 is or has been actively transposing. The main difference between the two sibling species is the presence of a large tadem array of the element in a well-defined heterochromatic location of theD. melanogaster genome, whereas such a cluster is absent inD. simulans. The presence ofBari-1 elements with apparently identical physical maps in allD. melanogaster andD. simulans strains examined suggests thatBari-1 is not a recent introduction in the genome of themelanogaster complex. Structural analysis reveals unusual features that distinguish it from other inverted repeat transposons, whereas many aspects are similar to the widely distributedTc1 element ofC. elegans.
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    Enzyme polymorphism inDrosophila melanogaster populations collected in two different habitats in Hungary (1995)
    Springer
    Genetica 96 (1995), S. 257-268 
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    ISSN: 1573-6857
    Keywords: Drosophila ; F-statistics ; genetic distance ; genetic drift ; habitat ; population structure ; selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The level of enzyme polymorphism was compared in tenDrosophila melanogaster populations collected in farmyards and distilleries in two regions of Hungary. The total genetic diversity was partitioned into between-and within-population components at each investigated locus using Wright's F-statistics. Population differentiation was studied in two different ways. Genetic distances between pairs of populations were calculated and a hierarchical analysis of gene diversity was performed. Based on the F values gene flow was estimated among the populations at different levels of the hierarchy. The results indicated that our ‘farmyard populations’ collected within a region could be considered as parallel samples from a panmictic population rather than samples of distinct populations. In distilleries, the flies might be influenced by two different evolutionary forces: (i) selection due to the extremely high concentration of ethanol in the fermenting mash and (ii) genetic drift due to the combination of repeated founder effects and fluctuating population size. Our results suggested that ‘distillery populations’ could not be regarded as real populations either. They could be considered as peculiar cases: founder individuals taken from the total population (region) established special populations which survived in the distilleries for many generations. Thus the dominating force acting on the ‘distillery populations’ was genetic drift.
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    Probing the evolution of senescence inDrosophila melanogaster withP-element tagging (1995)
    Springer
    Genetica 96 (1995), S. 225-234 
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    ISSN: 1573-6857
    Keywords: antagonistic pleiotropy ; Drosophila ; mutation accumulation ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural populations host a wealth of genetic variation in longevity and age-specific schedules of reproduction. This variation provides critical information for inferring the evolutionary origin of senescence. Patterns of mutational effects on age-specific fecundity and survival provide additional insight to distinguish alternative models of senescence. In this study,P-elements bearing thewhite minigene were inserted at random into a common genetic background, generating lines ofD. melanogaster with single, stable transposon inserts. A series of 48 single-P-element lines revealed statistically significant heterogeneity in both longevity and fecundity. Longevity and early fecundity were only weakly positively correlated (r=0.286,P=0.0398). Both the pooled sample and 30 of the individual lines exhibited a leveling of age-specific mortality at advanced ages, in opposition to the classical demographic models. To the extent that these mutational effects are representative of naturally-occurring mutations in heterogeneous populations, this result presents a problem for the evolutionary theory of senescence. Natural selection is inefficient at removing deleterious mutations that are expressed only at late ages, and selection may not differentiate between mutations whose effects on longevity are post-reproductive. A leveling of the mortality rate would also be seen if mutations whose expression is delayed until very late simply do not occur. A simulation of mutation-selection balance among the 48P-element tagged lines shows that the mean longevity declines monotonically with increasing mutation rate, consistent with the mutation-accumulation model.
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    Density and age-specific mortality (1995)
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    Genetica 96 (1995), S. 179-182 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; aging ; density ; mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Age-specific mortality rates decelerate at older ages in laboratory populations in the MedflyCeratitis capitata. This has been interpreted by Careyet al. (1992) to reflect a slowing of the aging process, but might also be explained by declining adult density. Here it is argued that the density explanation, as presented by Graves and Mueller (1993), is unpersuasive for several reasons: extrapolations fromDrosophila to Medflies are unjustified; the range of densities they studied is 2–120 times higher than that used in other studies; they ignore data on Medflies held in isolation, which rule out density effects; their own data suggest that initial cohort density has no effect on mortality rates at older ages, which is the relevant part of the life cycle; their experiment is too small to provide accurate estimates of mortality; new Medfly experiments executed at multiple densities show decelerating and then declining mortality rates at advanced ages for all densities. WhenDrosophila survivorship experiments are done on a sufficiently large scale they also show a deceleration of mortality at older ages that is not attributable to density effects. The deceleration of mortality rates is most likely a real facet of aging, and will have to be taken into consideration in any synthesis of the genetics and evolution of aging.
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    URL: http://dx.doi.org/10.1007/BF01439569
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    Feeding, reproductive and locomotor activities in diapausing and non-diapausing adults ofDrosophila (1995)
    Springer
    Ecological research 10 (1995), S. 87-93 
    Details
    ISSN: 1440-1703
    Keywords: diapause ; Drosophila ; feeding activity ; locomotor activity ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding, reproductive and locomotor activities of fourDrosophila species were studied under short and long daylengths at 15°C. A short daylength induced firm reproductive diapause in experimental strains ofD. subauraria andD. triauraria from northern Japan, but very shallow diapause in those ofD. lutescens andD. rufa from southern Japan. A subtropical strain ofD. triauraria had no diapause. The influence of diapause on feeding activity was detected only in aged (〉 12 day old) females; that is, the feeding activity was lower in diapausing females than in non-diapausing ones. Females that do not produce eggs would not require so much energy. On the other hand, young adults of the study species exhibited a high feeding activity and rapidly increased bodyweight irrespective of sex and the diapause state. They would need nutrition to build up their adult body. In males, the feeding activity decreased with age irrespective of the diapause state. Males would not require so much energy for reproductive activity. Diapausing males became heavier than non-diapausing males, perhaps because they accumulated triacylglycerols in fat bodies. However, female bodyweight did not differ by the diapause state, perhaps because diapausing females accumulated triacylglycerols and reproducing females had eggs in their ovaries. InD. triauraria, diapausing individuals exhibited somewhat lower locomotor activity than non-diapausing ones.
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    URL: http://dx.doi.org/10.1007/BF02347658
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    Yeast communities associated withDrosophila species and related flies in an eastern oak-pine forest: A comparison with western communities (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 484-494 
    Details
    ISSN: 1476-5535
    Keywords: Yeasts ; Drosophila ; Community ecology ; Cacti ; Tree-fluxes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Intestinal yeast mycobiota were studied in 14 species ofDrosophila and in the drosophilid speciesChymomyza amoena, captured at Pinery Provincial Park, Ontario. Over 56 yeast species, some undescribed, were isolated. These yeast communities were compared with those from two similar surveys conducted in western portions of North America. The community structures were influenced significantly by the habitat rather than phylogeny of the flies. Geographic separation was a factor affecting yeast taxa frequencies in the fly species, but it was largely overshadowed by ecological factors when the communities were described physiologically. The notion that habitats are filled by yeasts which add up to a suitable physiological potential, more or less independently of their taxonomic affinities, was thus confirmed.
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    URL: http://dx.doi.org/10.1007/BF01573963
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    Immunocytochemistry of a novel GABA receptor subunitRdl inDrosophila melanogaster (1995)
    Springer
    Invertebrate neuroscience 1 (1995), S. 25-31 
    Details
    ISSN: 1439-1104
    Keywords: Drosophila ; GABA receptors ; insecticide resistance ; cyclodiene insecticides ; immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Following our recent cloning of a novel γ-aminobutyric acid (GABA) receptor subunit geneResistance to dieldrin orRdl from the cyclodiene resistance locus inDrosophila melanogaster, we were interested in defining its pattern of expression during development. Here we report the raising of an anti-Rdl polyclonal antibody that recognizes a single protein of the expected 65 kDa size in immunoblots ofDrosophila head homogenates.In situ hybridization usingRdl cDNA probes and the anti-Rdl antibody shows thatRdl message and protein are highly expressed in the developing central nervous system (CNS) of 15–17 h embryos. Interestingly, despite the use of GABA in both the peripheral and CNS of insects,Rdl GABA receptor subunits appear to be confined to the CNS. Detailed immunocytochemistry ofDrosophila brain sections showed particularly strong anti-Rdl antibody staining in the optic lobes, ellipsoid body, fan shaped body, ventrolateral protocerebrum and the glomeruli of the antennal lobes. Results are compared with the distribution of staining observed in the insect CNS with antibodies against GABA itself and synaptotagmin, a synaptic vesicle protein.
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    URL: http://dx.doi.org/10.1007/BF02331829
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    Presynaptic proteins involved in exocytosis inDrosophila melanogaster: A genetic analysis (1995)
    Springer
    Invertebrate neuroscience 1 (1995), S. 3-13 
    Details
    ISSN: 1439-1104
    Keywords: exocytosis ; synaptic vesicles ; neurotransmitter release ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Neuronal communication involves the fusion of neurotransmitter filled synaptic vesicles with the presynaptic terminal. This exocytotic event depends upon proteins present in three separate compartments: the synaptic vesicle, the synaptic cytosol, and the presynaptic membrane. Recent data indicate that the basic components of exocytotic pathways, including those used for neurotransmitter release, are conserved from yeast to human. Genetic dissection of the secretory pathway in yeast, identification of the target proteins cleaved by the clostridial neurotoxins and biochemical characterization of the interactions of synaptic proteins from vertebrates have converged to provide the SNARE (soluble NSF attachment protein receptor) hypothesis for vesicle trafficking. This model proposes that proteins present in the vesicle (v-SNAREs) interact with membrane receptors (t-SNAREs) to provide a molecular scaffold for cytosolic proteins involved in fusion. The hypothesis that these mechanisms function at the synapse relies largely uponin vitro evidence. Recently, genetic approaches in mice, C.elegans and the fruitfly,Drosophila melanagaster, have been used to dissect thein vivo function of numerous proteins involved in synaptic transmission. This review covers recent progress and insights provided by a genetic dissection of neurotransmitter release inDrosophila. In addition, we will provide evidence that the mechanisms for synaptic communication are highly conserved from invertebrates to vertebrates, makingDrosophila an ideal model system to further unravel the intricacies of synaptic transmission.
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    URL: http://dx.doi.org/10.1007/BF02331827
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    Two visual pigment opsins, one expressed in the dorsal region and another in the dorsal and ventral regions, of the compound eye of a dragonfly,Sympetrum frequens (1995)
    Springer
    Invertebrate neuroscience 1 (1995), S. 33-39 
    Details
    ISSN: 1439-1104
    Keywords: rhodopsin ; opsin ; photoreceptor ; retina ; dragonfly (Sympetrum frequens) ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes the primary structure of two visual pigment opsins (DfRh1 and DfRh2) in the regionalized compound eye of a dragonfly,Sympetrum frequens. The amino acid sequences were deduced from the nucleotide sequences of cDNAs isolated from a cDNA library of the dragonfly retina. The two opsins both consist of 379 amino acids with 81.3% identity. Analysis of hydropathy indicated that the sequences have seven transmembrane domains like those of previously described opsins. Expression analysis using RT-PCR revealed that DfRh1 was present only in the dorsal region whereas DfRh2 was detected in both the dorsal and the ventral regions of the eye.
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    URL: http://dx.doi.org/10.1007/BF02331830
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    Yeast communities in a natural tequila fermentation (1995)
    Springer
    Antonie van Leeuwenhoek 68 (1995), S. 151-160 
    Details
    ISSN: 1572-9699
    Keywords: tequila ; fermentation ; agave ; yeast community ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fresh and cooked agave,Drosophila spp., processing equipment, agave molasses, agave extract, and fermenting must at a traditional tequila distillery (Herradura, Amatitan, Jalisco, México) were studied to gain insight on the origin of yeasts involved in a natural tequila fermentations. Five yeast communities were identified. (1) Fresh agave contained a diverse mycobiota dominated byClavispora lusitaniae and an endemic species,Metschnikowia agaveae. (2)Drosophila spp. from around or inside the distillery yielded typical fruit yeasts, in particularHanseniaspora spp.,Pichia kluyveri, andCandida krusei. (3)Schizosaccharomyces pombe prevailed in molasses. (4) Cooked agave and extract had a considerable diversity of species, but includedSaccharomyces cerevisiae. (5) Fermenting juice underwent a gradual reduction in yeast heterogeneity.Torulaspora delbrueckii, Kluyveromyces marxianus, andHanseniaspora spp. progressively ceded the way toS. cerevisiae, Zygosaccharomyces bailii, Candida milleri, andBrettanomyces spp. With the exception ofPichia membranaefaciens, which was shared by all communities, little overlap existed. That separation was even more manifest when species were divided into distinguishable biotypes based on morphology or physiology. It is concluded that crushing equipment and must holding tanks are the main source of significant inoculum for the fermentation process.Drosophila species appear to serve as internal vectors. Proximity to fruit trees probably contributes to maintaining a substantialDrosophila community, but the yeasts found in the distillery exhibit very little similarity to those found in adjacent vegetation. Interactions involving killer toxins had no apparent direct effects on the yeast community structure.
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    URL: http://dx.doi.org/10.1007/BF00873100
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    Intranuclear distribution of DNA topoisomerase II and chromatin (1995)
    Springer
    Chromosome research 3 (1995), S. 255-260 
    Details
    ISSN: 1573-6849
    Keywords: chromatin ; confocal microscopy ; Drosophila ; karyoskeleton ; topoisomerase II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Domain-specific anti-Drosophila DNA topoisomerase II antibodies were generated, affinity purified and used for confocal laser scanning immunofluorescence microscopy. Except for the nucleolus, DNA topoisomerase II is distributed throughout interphase nuclei. In adult accessory glands as well as third instar larval neural ganglion and imaginal disk nuclei, DNA topoisomerase II shows areas of co-localization with chromatin adjacent to areas of extrachromosomal distribution. These observations made in a variety of tissues under different fixation conditions and with a number of molecular probes support the notion that DNA topoisomerase II is a component of a substantially extrachromosomal network that functions to organize interphase chromatin within nuclei.
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    URL: http://dx.doi.org/10.1007/BF00713051
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