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  • Drosophila  (53)
  • Springer  (53)
  • Institute of Physics
  • 1995-1999
  • 1990-1994  (53)
  • 1940-1944
  • 1993  (53)
Collection
Publisher
Years
  • 1995-1999
  • 1990-1994  (53)
  • 1940-1944
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 67 (1993), S. 233-239 
    ISSN: 1570-7458
    Keywords: inbreeding ; colonization ; isofemale line ; Drosophila ; Diptera ; Leptopilina boulardi ; Cynipidae ; Hymenoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. melanogaster (Meigen) a été utilisé pour tester la capacité des lignées isofemelles à conserver la variabilité génétique d'une population naturelle. Deux types d'expériences ont été réalisées. L'une a consisté à déterminer la variabilité génétique de 3 locus enzymatiques pour 32 lignées isofemelles à la première et à la 23ème génération d'élevage au laboratoire. L'autre a consisté à tester la capacité des larves à éliminer un parasitoïde par le processus d'encapsulation après 8 années d'élevage au laboratoire. D'une façon générale, certaines lignées isofemelles perdent de la variabilité durant les 23 générations de l'étude. Mais la fréquence globale des allèles reste inchangée si l'on considère l'ensemble des 32 lignées. Le seul allèle rare observé a également été conservé. Les modifications des fréquences allèliques à chacun des locus ont lieu de façon indépendante les unes des autres. La variabilité génétique d'un caractère biologique, la capacité des larves à encapsuler le parasitoïde, a également varié, mais elle a pu être restaurée à un niveau proche de la population initiale en rassemblant plusieurs individus de chacune des lignées.
    Notes: Abstract Drosophila melanogaster (Meigen) was used to test the power of isofemale lines in preserving genetic variability. We performed experiments in two ways. One series consisted of measuring the genetic variability for three enzymatic loci in 32 isofemale lines, in the first and 23rd generations of culture. In the second series, we tested the capacity of the larvae to eliminate a parasitoid by encapsulation after eight years of laboratory breeding. In general, individual isofemale lines appeared to change during the 23 generations of the study, but the global frequency of these alleles among the 32 isofemale lines stayed relatively unchanged. The only rare allele observed was also conserved. Changes in allozyme frequencies at any one locus were independent of those at other loci. Genetic variation of a biological trait, the capacity of the larvae to encapsulate a parasitoid, also changed, but it could be restored to a level close to that of the starting population by mass hybridizing together individuals of each line.
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  • 2
    ISSN: 1572-8889
    Keywords: Hymenoptera ; Leptopilina ; Drosophila ; semiochemicals ; kairomones ; parasitoid ; generalist ; specialist ; foraging behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foraging parasitoids are thought to need more specific information than generalists on the presence, identity, availability, and suitability of their insect host species. In the present paper, we compare responses to host kairomones by two phylogenetically related parasitoid species that attack Drosophilidae and that differ in the width of their host range. As predicted, the behavioral response of the parasitoids to host kairomones reflected their difference in host range. The response of the specialist parasitoid Leptopilina boulardiwas restricted to contact kairomones from its natural hosts and one closely related species. In contrast, the generalist parasitoid Leptopilina heterotomaresponded to contact kairomones of a variety of Drosophilidae species.
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  • 3
    ISSN: 1420-9071
    Keywords: Drosophila ; hybridization ; male vigour ; male mating speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic variation has been found in males of aD. simulans population for their eagerness to hybridize withD. melanogaster females. In a search for traits involved in this hybridization, males ofD. simulans were tested for mating speed and sexual vigour. Between-male differences were detected in both sexual traits, but no relationship was noticed between them, nor with the frequency of hybridization. Thus male mating propensities appear to be unrelated to the breakdown of sexual isolation between these sibling species.
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  • 4
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    Journal of molecular evolution 37 (1993), S. 483-495 
    ISSN: 1432-1432
    Keywords: Drosophila ; mastermind ; Gene comparison ; Triplet repeat ; Homopolymer ; Protein evolution ; Repeat length variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Runs of identical amino acids encoded by triplet repeats (homopolymers) are components of numerous proteins, yet their role is poorly understood. Large numbers of homopolymers are present in the Drosophila melanogaster mastermind (mam) protein surrounding several unique charged amino acid clusters. Comparison of mam sequences from D. virilis and D. melanogaster reveals a high level of amino acid conservation in the charged clusters. In contrast, significant divergence is found in repetitive regions resulting from numerous amino acid replacements and large insertions and deletions. It appears that repetitive regions are under less selective pressure than unique regions, consistent with the idea that homopolymers act as flexible spacers separating functional domains in proteins. Notwithstanding extensive length variation in intervening homopolymers, there is extreme conservation of the amino acid spacing of specific charge clusters. The results support a model where homopolymer length variability is constrained by natural selection.
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  • 5
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    Journal of molecular evolution 37 (1993), S. 525-543 
    ISSN: 1432-1432
    Keywords: Drosophila ; Zaprionus ; Phylogeny ; Ribosomal RNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nucleotide sequences of 72 species of Drosophilidae were determined for divergent D1 and D2 domains (representing 200 and 341 nucleotides respectively in D. melanogaster) of large ribosomal RNA, using the rRNA direct sequencing method. Molecular phylogenetic trees were reconstructed using both distance and parsimony methods and the robustness of the nodes was evaluated by the bootstrap procedure. The trees obtained by these methods revealed four main lineages or clades which do not correspond to the taxonomical hierarchy. In our results, the genus Chymomyza is associated with the subgenus Scaptodrosophila of the genus Drosophila and their cluster constitutes the most ancient clade. The two other clades are constituted of groups belonging to the subgenus Sophophora of the genus Drosophila: the so-called Neotropical clade including the willistoni and saltans groups and the obscura-melanogaster clade itself split into three lineages: (1) obscura group + ananassae subgroup, (2) montium subgroup, and (3) melanogaster + Oriental subgroups. The fourth clade, the Drosophila one, contains three lineages. D. polychaeta, D. iri, and D. fraburu are branched together and constitute the most ancient lineage; the second lineage includes the annulimana, bromeliae, dreyfusi, melanica, mesophragmatica, repleta, robusta, and virilis groups. The third lineage is composed of the immigrans and the cardini, funebris, guaramunu, guarani, histrio, pallidipennis, quinaria, and tripunctata groups. The genera Samoaia, Scaptomyza, and Zaprionus are branched within the Drosophila clade. Although these four clades appear regularly in almost all tree calculations, additional sequencing will be necessary to determine their precise relationships.
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  • 6
    ISSN: 1432-1432
    Keywords: Drosophila ; dec-1 eggshell gene ; Wild-type variants ; Repeated region ; DNA sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thedec-1 eggshell gene inDrosophila melanogaster encodes follicle cell proteins required for proper eggshell assembly. As shown by Southern and Northern analyses thedec-1 gene occurs in four alleles (Fcl-4) among wild-type strains. Its second exon has a distinct feature in the form of 12 repeats with 78–91 nucleotides; the first five show nearly 100% homology. DNA sequence comparison of the repeated region of the alleles revealed that the length polymorphisms are caused by changes in the numbers of the first five repeats. The results suggest that the alleles have been generated by unequal intragenic crossing-over and/or slippage during DNA replication and that the allelic length variants have arisen independently. The possiblilty that the most common allele,FC1, has a selective advantage over the other alleles is discussed.
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  • 7
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    Journal of molecular evolution 36 (1993), S. 315-326 
    ISSN: 1432-1432
    Keywords: Drosophila ; Fushi tarazu ; Functional constraints ; Regulatory elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have studied the evolutionary changes occurring in the noncoding regions around the developmentally important fushi tarazu (ftz) gene in a total of 11 species in the genus Drosophila. Previous molecular developmental studies have identified DNA elements both 3′ and 5′ to the coding region which are important in proper regulation of expression of the Drosophila melanogaster ftz gene. We show here that these same elements are the most evolutionarily conserved regions in the vicinity of the gene homologs. Parts of some control elements are more conserved than exonic sequences. Not only is there sequence conservation, but the relative position, orientation, and distances among the control elements remain conserved. One quite significant difference does exist between the two major subgenera studied, Sophophora and Drosophila: namely, an inversion of the ftz unit with respect to other genes in the Antennapedia complex, ANT-C. As a comparison, we applied similar analysis to a “housekeeping” gene-rosy (ry), or Xdh. In contrast, DNA sequences 5′ to the ry coding region revealed little evolutionary conservation. These studies bear out the proposition that functionally important DNA sequences remain more conserved through evolutionary time than do less functionally important sequences. This proposition could be tested in the present case because we could predict a priori from the developmental studies which DNA regions should be most conserved.
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  • 8
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    Journal of comparative physiology 172 (1993), S. 303-308 
    ISSN: 1432-1351
    Keywords: Drosophila ; Photoreception ; Magnetoreception ; Magnetic compass orientation ; Geomagnetic field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. Wildtype Oregon-R Drosophila melanogaster were trained in the ambient magnetic field to a horizontal gradient of 365 nm light emanating from one of the 4 cardinal compass directions and were subsequently tested in a visually-symmetrical, radial 8-arm maze in which the magnetic field alignment could be varied. When tested under 365 nm light, flies exhibited consistent magnetic compass orientation in the direction from which light had emanated in training. 2. When the data were analyzed by sex, males exhibited a strong and consistent magnetic compass response while females were randomly oriented with respect to the magnetic field. 3. When tested under 500 nm light of the same quantal flux, females were again randomly oriented with respect to the magnetic field, while males exhibited a 90° clockwise shift in magnetic compass orientation relative to the trained direction. 4. This wavelength-dependent shift in the direction of magnetic compass orientation suggests that Drosophila may utilize a light-dependent magnetic compass similar to that demonstrated previously in an amphibian. However, the data do not exclude the alternative hypothesis that a change in the wavelength of light has a non-specific effect on the flies' behavior, i.e., causing the flies to exhibit a different form of magnetic orientation behavior.
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  • 9
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    Journal of molecular evolution 36 (1993), S. 127-135 
    ISSN: 1432-1432
    Keywords: Transposable elements ; Drosophila ; Gypsy ; Horizontal transfer ; In situ hybridization ; Molecular evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Characterization of sequences homologous to theDrosophila melanogaster gypsy transposable element was carried out inDrosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species.GypsyDS sequences are located in both euchromatic and heterochromatic regions. A completegypsyDS sequence was isolated from aD. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of theD. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that there is greater similarity between theD. subobscura-D. virilis sequences than betweenD. subobscura andD. melanogaster. Molecular divergence ofgypsy sequences betweenD. virilis andD. subobscura is estimated at 16 MY, whereas the most likely divergence time of these two species is more than 60 MY. These data strongly suggest thatgypsy sequences have been horizontally transferred between these species.
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  • 10
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    Journal of molecular evolution 36 (1993), S. 214-223 
    ISSN: 1432-1432
    Keywords: Drosophila ; Mitochondrial DNA ; Length polymorphisms ; A+T-rich region ; Tandem duplicated sequences ; Nucleotide sequences ; Secondary structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the twelve Drosophila obscura group species studied, belonging to the affinis, obscura, and pseudoobscura subgroups, the mitochondrial DNA length ranges from 15.8 to 17.2 kb. This length polymorphism is mainly due to insertions/deletions in the variable region of the A+T-rich region. In addition, one species (D. tristis) possess a tandem duplication of a 470-bp fragment that contains the replication origin. The same duplication has occurred at least twice in the Drosophila evolutionary history due to the fact that the repetition is analogous to repetitions found in the four species of the D. melanogaster complex. By comparing the nucleotide sequence of the conserved region in D. ambigua, D. obscura, D. yakuba, D. teissieri, and D. virilis, we show the presence of a secondary structure, likely implied in the replication origin, which could favor the generation of this kind of duplications. Finally, we propose that the high A and T content in the variable region of the A + T-rich region favors the formation of less-stable secondary structures, which could explain the generation of minor insertion/deletions found in this region.
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  • 11
    ISSN: 1432-1432
    Keywords: Drosophila ; Glucose repression ; Amylase gene ; Interspecific promoter function ; Conserved cis-acting elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Previous studies have demonstrated that the expression of the α-amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the α-amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.
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  • 12
    ISSN: 1432-1432
    Keywords: rp49 gene ; Drosophila ; Sequence divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 2.1-kb SStI fragment including the rp49 gene and the 3′ end of the δ-serendipity gene has been cloned and sequenced in Drosophila pseudoobscura. rp49 maps at region 62 on the tip of chromosome II of this species. Both the coding and flanking regions have been aligned and compared with those of D. subobscura. There is no evidence for heterogeneity in the rate of silent substitution between the rp49 coding region and the rate of substitutions in flanking regions, the overall silent divergence per site being 0.19. Noncoding regions also differ between both species by different insertions/deletions, some of which are related to repeated sequences. The rp49 region of D. pseudoobscura shows a strong codon bias similar to those of D. subobscura and D. melanogaster. Comparison of the rates of silent (K S ) and nonsilent (K a ) substitutions of the rp49 gene and other genes completely sequenced in D. pseudoobscura and D. melanogaster confirms previous results indicating that rp49 is evolving slowly both at silent and nonsilent sites. According to the data for the rp49 region, D. pseudoobscura and D. subobscura lineages would have diverged some 9 Myr ago, if one assumes a divergence time of 30 Myr for the melanogaster and obscura groups.
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  • 13
    ISSN: 1432-1432
    Keywords: Evolution ; Gene regulation ; Drosophila ; Adaptation ; Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.
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  • 14
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    Development genes and evolution 203 (1993), S. 83-91 
    ISSN: 1432-041X
    Keywords: Drosophila ; Monensin ; Extracellular matrix ; Membrane proteins ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extracellular matrix and membrane proteins and their correct secretion probably are key elements in morphogenesis and differentiation in Drosophila. In this study, we have analysed the effects of monensin, a Na+-H+-ionophore which blocks normal secretion, applied during cellular blastoderm formation on further development. Normal cell morphology and intercellular contacts are lost and the extracellular matrix becomes disorganized. Gastrulation is blocked and abnormal foldings can be observed. Cuticle phenotypes showed different degrees of ventral, dorsal, head and posterior defects. The results are discussed in the context of what is known about membrane and extracellular matrix proteins in Drosophila.
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  • 15
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    Development genes and evolution 202 (1993), S. 159-169 
    ISSN: 1432-041X
    Keywords: Drosophila ; Choline acetyltransferase ; cis-Regulatory element ; lacZ reporter gene ; Colinergic neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Choline acetyltransferase (ChAT, EC 2.3.1.6) catalyzes the production of the neurotransmitter acetylcholine, and is an essential factor for neurons to be cholinergic. We have analyzed regulation of the Drosophila ChAT gene during development by examining the β-galactosidase expression pattern in transformed lines carrying different lengths of 5′ flanking DNA fused to a lacZ reporter gene. The largest fragment tested, 7.4 kb, resulted in the most extensive expression pattern in embryonic and larval nervous system and likely reflects all the cis-regulatory elements necessary for ChAT expression. We also found that 5′ flanking DNA located between 3.3 kb and 1.2 kb is essential for the reporter gene expression in most of the segmentally arranged embryonic sensory neurons as well as other distinct cells in the CNS. The existence of negative regulatory elements was suggested by the observation that differentiating photoreceptor cells in eye imaginal discs showed the reporter gene expression in several 1.2 kb and 3.3 kb transformants but not in 7.4 kb transformants. Furthermore, we have fused the 5′ flanking DNA fragments to a wild type ChAT cDNA and used these constructs to transform Drosophila with a Cha mutant background. Surprisingly, even though different amounts of 5′ flanking DNA resulted in different spatial expression patterns, all of the positively expressing cDNA transformed lines were rescued from lethality. Our results suggest that developmental expression of the ChAT gene is regulated both positively and negatively by the combined action of several elements located in the 7.4 kb upstream region, and that the more distal 5′ flanking DNA is not necessary for embryonic survival and development to adult flies.
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  • 16
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    Development genes and evolution 202 (1993), S. 371-381 
    ISSN: 1432-041X
    Keywords: Neurogenesis ; Drosophila ; Neurogenic genes ; PNS ; Lineage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Drosophila, mutations in a class of genes, the neurogenic genes, produce an excess of neurons. This neural hyperplasia has been attributed to the formation of more than the normal number of neuronal precursor cells at the expense of epidermal cells. In order to find out whether the neurogenic genes only act at this intial step of neurogenesis, we studied the replication pattern of the sensory organ precursor cells by monitoring BrdU incorporation in embryos mutant for Notch (N), Delta (Dl), mastermind (mam), almondex (amx), neuralized (neu), big brain (bib) and the Enhancer of split-Complex (E(spl)-C). Using temperature sensitive alleles of two of the neurogenic genes, DI and N, we also induced an acute increase of replicating sensory precursors by shifting briefly to the restricted temperature. We have found that the loss of function of all the seven neurogenic loci that were tested causes an increase in replicating sensory precursor cells, consistent with the model that these neurogenic genes normally participate in the process of restricting the number of neuronal precursors. Whereas the temporal pattern of replication appeared normal in mutants of five of the seven neurogenic loci, in N and mam embryos replicating PNS cells are present beyond the time when they normally undergo replication. Experiments with colchicine suggest that many of these late replicating cells may be newly emerging precursors and probably not additional cell divisions of already recruited precursors. Thus, different neurogenic genes may be required over different periods of time for the specification of sensory precursor cells.
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  • 17
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    Development genes and evolution 202 (1993), S. 112-122 
    ISSN: 1432-041X
    Keywords: Axon guidance ; Drosophila ; Enhancer trap ; Kinesin-lacZ ; Neural development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the development of neuronal projections inDrosophila by fusing the gene encodingDrosophila kinesin, a microtubule-associated motor protein, toEscherichia coli lacZ, and employing the resulting chimeric protein as a reporter molecule for labelling cells by the “enhancer-trap” method. Expression of kinesin-β-galactosidase in neurons has afforded a detailed view of the morphologies and projections of neurons. The images of cells provided by this method will facilitate anatomical and genetic investigations of theDrosophila nervous system as well as other cell types.
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  • 18
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    Development genes and evolution 203 (1993), S. 60-73 
    ISSN: 1432-041X
    Keywords: Head development ; Eye-antenna disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The embryonic development of the primordia of the Drosophila head was studied by using an enhancer trap line expressed in these structures from embryonic stage 13 onward. Particular attention was given to the question of how the adult head primordia relate to the larval head segments. The clypeo-labral bud to the stage 13 embryo is located at a lateral position in the labrum adjacent to the labral sensory complex (“epiphysis”). Both clypeo-labral bud and sensory complex are located anterior to the engrailed-expression domain of the labrum. Throughout late embryogenesis and the larval period, the clypeo-labral bud forms integral part of the epithelium lining the roof of the atrium. The labial disc originates from the lateral labial segment adjacent to the labial sensory complex (“hypophysis”). It partially overlaps with the labial en-domain. After head involution, the labial disc forms a small pocket in the ventro-lateral wall of the atrium. The eye-antenna disc develops from a relatively large territory occupying the dorso-posterior part of the procephalic lobe, as well as parts of the dorsal gnathal segments. Cells in this territory are greatly reduced in number by cell death during stages 12–14. After head involution, the presumptive eye-antenna disc occupies a position in the lateral-posterior part of the dorsal pouch. Evagination of this tissue occurs during the first hours after hatching. In the embryo, no en-expression is present in the presumptive eye-antenna disc. en-expression starts in three separate regions in the third instar larva.
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  • 19
    ISSN: 1432-1939
    Keywords: Hymenoptera ; Eucoilidae ; Leptopilina heterotoma ; Infochemicals ; Kairomone ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Parasitoids that forage for herbivorous hosts by using infochemicals may have a problem concerning the reliability and detectability of these stimuli: host stimuli are highly reliable but not very detectable at a distance, while stimuli from the host's food are very detectable but generally not very reliable in indicating host presence. One solution to this problem is to learn to link highly detectable stimuli to reliable but not very detectable stimuli. Ample knowledge is available on how associative learning aids foraging parasitoids in the location of suitable microhabitats. However, in this paper we report on another solution to the reliability-detectability problem and present evidence for an essential, but as yet overlooked, aspect of Drosophila parasitoid ecology. For the first time it is shown that a parasitoid of Drosophila larvae spies on the communication system of adult Drosophila flies to locate potential host sites: naive parasitoids strongly respond to a volatile aggregation pheromone that is deposited in the oviposition site by recently mated female flies. Thus, the parasitoids resort to using highly detectable information from a host stage different from the one under attack (i.e. infochemical detour). The function and ecological implications of these findings are discussed.
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  • 20
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    Behavior genetics 23 (1993), S. 85-90 
    ISSN: 1573-3297
    Keywords: period gene ; Drosophila ; genetic coupling ; coevolution ; sexual selection ; female preference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Mutations at theperiod (per) locus inDrosophila melanogaster alter rhythmic components of the male courtship song. We have examined the mating speed of females homozygous for mutantper alleles when presented with artificial mutant songs. Mutant females retain a preference for wild-type over mutant songs, thus male song and female preference are probably under separate genetic control. In contrast,per-mutant females from an established laboratory stock which had been maintained for nearly two decades appear to have an enhanced response to the corresponding mutant song in that they no longer discriminate against mutant song. These results are discussed in terms of the “genetic coupling” and “coevolution” theories of complementarity between male and female components of communication systems.
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  • 21
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    Biochemical genetics 31 (1993), S. 393-407 
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenases ; protein evolution ; Drosophila ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Polyclonal antibodies raised against purifiedDrosophila alcohol dehydrogenase (ADH) were used in Western blot analyses to search for structurally and/or immunologically related proteins in prokaryotes and eukaryotes. No immunological-reactive protein was detected in a flesh fly, a locust, and butterflies. Immunological similarity with the 50-kDa PQQ-glucose dehydrogenase (GluDH)-B enzyme ofAcinetobacter calcoaceticus was found, but the cross-reactivity apparently is dependent on the high hydrophilic character of this protein. Antibodies against PQQ-GluDH did not recognizeDrosophila ADH. In five of seven species of the gram-positive soil bacteria actinomycetes tested, a protein approximately 28–30 kDa in subunit size was strongly recognized by α-DADH. It is probably not one of the two proteins with known homology toDrosophila ADH,viz., theactIII gene product and 20β-hydroxysteroid dehydrogenase. The protein is present in both the soluble and the pellet-membrane fraction of the cells. The protein has a late temporal expression in surface-grown cultures and, therefore, might be involved in secondary metabolism.
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  • 22
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    Biochemical genetics 31 (1993), S. 61-74 
    ISSN: 1573-4927
    Keywords: isofemale ; allele frequency estimation ; population structure ; allozyme ; microsatellites ; restriction fragment length polymorphisms ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Isofemale lines are commonly used inDrosophila and other genera for the purpose of assaying genetic variation. Isofemale lines can be kept in the laboratory for many generations before genetic work is carried out, and permit the confirmation of newly discovered alleles. A problem not realized by many workers is that the commonly used estimate of allele frequency from these lines is biased. This estimation bias occurs at all times after the first laboratory generation, regardless of whether single individuals or pooled samples are used in each well of an electrophoretic gel. This bias can potentially affect the estimation of population genetic parameters, and in the case of rare allele analysis it can cause gross overestimates of gene flow. This paper provides a correction for allele frequency estimates derived from isofemale lines for any time after the lines are established in the laboratory. When pooled samples are used, this estimator performs better than the standard estimator at all times after the first generation. The estimator is also insensitive to multiple inseminations. After the lines have drifted oneN e generations, multiple inseminations actually make the new estimator perform better than it does in singly inseminated females. Simulations show that estimates made using either estimator after the lines have drifted to fixation have a much greater error associated with their use than do those estimates made earlier in time using the correction. In general it is better to use corrected estimates of gene frequency soon after lines are established than to use uncorrected estimates made after the first laboratory generation.
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  • 23
    ISSN: 1573-4927
    Keywords: serine esterase ; substrate interactions ; Drosophila ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase 6 fromDrosophila melanogaster is a carboxylesterase that belongs to the serine esterase multigene family. It has a basic histidine (His) at residue 187, adjacent to the reactive serine (Ser) at residue 188, whereas most other characterized members of the family have an acidic glutamate (Glu) in the equivalent position. We have used site-directedin vitro mutagenesis to replace the His codon of the esterase 6 gene with either Gln or Glu codons. The enzymes encoded by these active-site mutants and a wild-type control have been expressed, purified, and characterized. Substitution of Gln for His at position 187 has little effect on the biochemical properties of esterase 6, but the presence of Glu at this position is associated with three major differences. First, the pH optimum is increased from 7 to 9. Second, the mutant enzyme shows decreased activity for β-naphthyl esters andp-nitrophenyl acetate but has gained the ability to hydrolyze acetylthiocholine. Finally, the Gibb's free energy of activation for the enzyme is increased. These results suggest that residue 187 interacts directly with the substrate alkyl group and that this interaction is fully realized in the transition state. We further propose that the presence of His rather than Glu at position 187 in esterase 6 contributes significantly to its functional divergence from the cholinesterases and that this divergence is due to different interactions between residue 187 and the substrate alkyl group.
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  • 24
    ISSN: 1573-4927
    Keywords: serine esterase ; substrate interactions ; Drosophila ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase 6 fromDrosophila melanogaster is a carboxylesterase that belongs to the serine esterase multigene family. It has a basic histidine (His) at residue 187, adjacent to the reactive serine (Ser) at residue 188, whereas most other characterized members of the family have an acidic glutamate (Glu) in the equivalent position. We have used site-directedin vitro mutagenesis to replace the His codon of the esterase 6 gene with either Gln or Glu codons. The enzymes encoded by these active-site mutants and a wild-type control have been expressed, purified, and characterized. Substitution of Gln for His at position 187 has little effect on the biochemical properties of esterase 6, but the presence of Glu at this position is associated with three major differences. First, the pH optimum is increased from 7 to 9. Second, the mutant enzyme shows decreased activity for β-naphthyl esters andp-nitrophenyl acetate but has gained the ability to hydrolyze acetylthiocholine. Finally, the Gibb’s free energy of activation for the enzyme is increased. These results suggest that residue 187 interacts directly with the substrate alkyl group and that this interaction is fully realized in the transition state. We further propose that the presence of His rather than Glu at position 187 in esterase 6 contributes significantly to its functional divergence from the cholinesterases and that this divergence is due to different interactions between residue 187 and the substrate alkyl group.
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  • 25
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    Biochemical genetics 31 (1993), S. 375-391 
    ISSN: 1573-4927
    Keywords: Drosophila ; sulfite oxidase ; molybdenum ; MoCo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between sulfite oxidase (SO) and sulfite sensitivity inDrosophila melanogaster is addressed. Significant improvements to the SO assay have provided an investigative tool which can be applied to further studies of this molybdoenzyme. Using the second-instar larval stage ofD. melanogaster, we have shown a direct relationship between measured levels of sulfite oxidase activity and the organism's ability to withstand a sulfite challenge. Implementation of a sulfite-testing procedure confirmed the documented instability of sulfite in solution and may explain some of the conflicting results reported in the SO literature. Results of the tungstate-addition experiments confirm thatDrosophila SO is a molybdoenzyme and its activity was shown to be governed by three of the four loci known to affect more than one molybdoenzyme. The ability ofD. melanogaster to withstand the application of exogenous sulfites is shown to be dependent on sulfite oxidase activity.
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  • 26
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    Biochemical genetics 31 (1993), S. 393-407 
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenases ; protein evolution ; Drosophila ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Polyclonal antibodies raised against purifiedDrosophila alcohol dehydrogenase (ADH) were used in Western blot analyses to search for structurally and/or immunologically related proteins in prokaryotes and eukaryotes. No immunological-reactive protein was detected in a flesh fly, a locust, and butterflies. Immunological similarity with the 50-kDa PQQ-glucose dehydrogenase (GluDH)-B enzyme ofAcinetobacter calcoaceticus was found, but the cross-reactivity apparently is dependent on the high hydrophilic character of this protein. Antibodies against PQQ-GluDH did not recognizeDrosophila ADH. In five of seven species of the gram-positive soil bacteria actinomycetes tested, a protein approximately 28–30 kDa in subunit size was strongly recognized by α-DADH. It is probably not one of the two proteins with known homology toDrosophila ADH,viz., theactIII gene product and 20β-hydroxysteroid dehydrogenase. The protein is present in both the soluble and the pellet-membrane fraction of the cells. The protein has a late temporal expression in surface-grown cultures and, therefore, might be involved in secondary metabolism.
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  • 27
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    Biochemical genetics 31 (1993), S. 375-391 
    ISSN: 1573-4927
    Keywords: Drosophila ; sulfite oxidase ; molybdenum ; MoCo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between sulfite oxidase (SO) and sulfite sensitivity inDrosophila melanogaster is addressed. Significant improvements to the SO assay have provided an investigative tool which can be applied to further studies of this molybdoenzyme. Using the second-instar larval stage ofD. melanogaster, we have shown a direct relationship between measured levels of sulfite oxidase activity and the organism's ability to withstand a sulfite challenge. Implementation of a sulfite-testing procedure confirmed the documented instability of sulfite in solution and may explain some of the conflicting results reported in the SO literature. Results of the tungstate-addition experiments confirm thatDrosophila SO is a molybdoenzyme and its activity was shown to be governed by three of the four loci known to affect more than one molybdoenzyme. The ability ofD. melanogaster to withstand the application of exogenous sulfites is shown to be dependent on sulfite oxidase activity.
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  • 28
    ISSN: 1432-1424
    Keywords: Drosophila ; per mutants ; pertransgenic ; Lucifer Yellow injections ; Gap junctions
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larval salivary gland cells of Drosophila melanogaster were injected with a fluorescent dye to assess strengths of intercellular communication among such cells, as influenced by mutations at the period locus and by a per transgene. This clock gene had been reported to increase the extent of dye transfer when mutated such that it shortens the period of biological rhythms; the previous study also showed that a per-null mutant decreased the strength of transfer among salivary gland cells. Our re-examination of this feature of larval physiology—in observer-blind analyses, using the per s and per o mutants as well as two per-normal strains—revealed no appreciable differences in extents of dye transfer among these four genotypes. These results are discussed in the context of emerging findings which suggest that the period gene's product controls pacemaker functioning as an intracellularly acting entity.
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  • 29
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    Behavioral ecology and sociobiology 33 (1993), S. 383-391 
    ISSN: 1432-0762
    Keywords: Operational sex ratio ; Maxim system ; Sperm ; Age of maturity ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Males of the cactophilic fruitfly, Drosophila pachea, produce relatively few but very large sperm, and partition their limited gamete numbers among successive mates. The present study found that males take 10 days longer than females, post-eclosion, to become sexually mature. The pattern of testes development suggests that the need to produce testes long enough to manufacture the giant sperm is the cause of the delayed male maturity. These findings generate the prediction that the operational sex ratio (OSR) of populations will be female-biased. The size, sex ratio, and OSR of natural populations were examined. In general, local populations tended to be small and sex ratios tended to be slightly male-biased. However, as predicted, the OSR of populations, at least in one season, tended to be female-biased, with an average of 2.3 receptive females for each sexually active male. Results of laboratory experiments to determine the relationship between female remating frequency and fitness, and between population OSR and productivity, suggest that natural populations with female-biased OSRs are sperm-limited. The origin and maintenance of sperm gigantism and the unusual sperm-partitioning behavior of males are discussed with respect to population structure.
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  • 30
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    Molecular genetics and genomics 239 (1993), S. 109-114 
    ISSN: 1617-4623
    Keywords: Drosophila ; melanogaster ; rough ; 97D
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    Topics: Biology
    Notes: Abstract The rough homeobox gene of D. melanogaster is required for the correct patterning of the developing eye. The locus maps to cytological location 97D2-5, a region which has not been extensively characterised. As part of our genetic and molecular characterization of rough we carried out an EMS mutagenesis to generate mutants that map to the surrounding region, 97D2-9 which is deleted in Df(3R)ro-XB3. We have generated 1 visible and 13 lethal mutations which, together with the previously described Toll and ms(3)K10 loci, and other unpublished lethals, define nine complementation groups — four lethal, three semi-lethal, one visible and one male-sterile. In addition to rough, one other locus within this region, 1(3)97De, was shown to be required for formation of the normal pattern of photoreceptor cells in the compound eye.
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  • 31
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    Biochemical genetics 31 (1993), S. 29-50 
    ISSN: 1573-4927
    Keywords: Drosophila ; peptidase ; activity modifiers ; kinetic parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The peptidase system inDrosophila melanogaster (dipeptidase-A, -B, and -C and leucine aminopeptidases G and P) was used as a model to study the effects of modifier genes on activity of enzymes with similar functions. A screen of X, second, and third chromosome substitution isogenic lines revealed the presence of activity modifiers for peptidases on all three chromosomes. Correlation analyses indicated that covariation between some of the peptidase activities is independent of genetic background, while others are associated with variable second chromosomes. Chromosome-specific effects onK m ,V max, and specific activity of partially purified peptidases were also detected. Moreover, a repeatable technique using anion-exchange column chromatography allowed the characterization of possibly two putative peptidic enzymes, glycyl-l-isoleucine-ase andl-leucyl-l-proline-ase, whose kinetic properties differ from the dipeptidases and the leucine aminopeptidases. These findings confirm the existence of activity modifiers for peptidases, much like other enzymes inDrosophila melanogaster.
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  • 32
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    Biochemical genetics 31 (1993), S. 61-74 
    ISSN: 1573-4927
    Keywords: isofemale ; allele frequency estimation ; population structure ; allozyme ; microsatellites ; restriction fragment length polymorphisms ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Isofemale lines are commonly used inDrosophila and other genera for the purpose of assaying genetic variation. Isofemale lines can be kept in the laboratory for many generations before genetic work is carried out, and permit the confirmation of newly discovered alleles. A problem not realized by many workers is that the commonly used estimate of allele frequency from these lines is biased. This estimation bias occurs at all times after the first laboratory generation, regardless of whether single individuals or pooled samples are used in each well of an electrophoretic gel. This bias can potentially affect the estimation of population genetic parameters, and in the case of rare allele analysis it can cause gross overestimates of gene flow. This paper provides a correction for allele frequency estimates derived from isofemale lines for any time after the lines are established in the laboratory. When pooled samples are used, this estimator performs better than the standard estimator at all times after the first generation. The estimator is also insensitive to multiple inseminations. After the lines have drifted oneN e generations, multiple inseminations actually make the new estimator perform better than it does in singly inseminated females. Simulations show that estimates made using either estimator after the lines have drifted to fixation have a much greater error associated with their use than do those estimates made earlier in time using the correction. In general it is better to use corrected estimates of gene frequency soon after lines are established than to use uncorrected estimates made after the first laboratory generation.
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  • 33
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    Biochemical genetics 31 (1993), S. 29-50 
    ISSN: 1573-4927
    Keywords: Drosophila ; peptidase ; activity modifiers ; kinetic parameters
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The peptidase system inDrosophila melanogaster (dipeptidase-A, -B, and -C and leucine aminopeptidases G and P) was used as a model to study the effects of modifier genes on activity of enzymes with similar functions. A screen of X, second, and third chromosome substitution isogenic lines revealed the presence of activity modifiers for peptidases on all three chromosomes. Correlation analyses indicated that covariation between some of the peptidase activities is independent of genetic background, while others are associated with variable second chromosomes. Chromosome-specific effects onK m ,V max, and specific activity of partially purified peptidases were also detected. Moreover, a repeatable technique using anion-exchange column chromatography allowed the characterization of possibly two putative peptidic enzymes, glycyl-l-isoleucine-ase andl-leucyl-l-proline-ase, whose kinetic properties differ from the dipeptidases and the leucine aminopeptidases. These findings confirm the existence of activity modifiers for peptidases, much like other enzymes inDrosophila melanogaster.
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  • 34
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    Evolutionary ecology 7 (1993), S. 103-108 
    ISSN: 1573-8477
    Keywords: host-parasite interactions ; coevolution ; host specificity ; Drosophila ; Howardula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In eastern North America, the nematodeHowardula aoronymphium parasitizes four species of mushroom-breedingDrosophila:D. falleni andD. recens of the quinaria species group, andD. putrida andD. testacea of the testacea group. One strain ofH. aoronymphium, designated Mendon-87, was initially capable of infecting all four of these host species. After less than 3 years in laboratory culture usingD. falleni as the sole host, this strain had completely lost the ability to infectD. putrida. Two other nematode strains parasitizedD. falleni andD. putrida at equal rates. These results demonstrate the existence of genetic variation for host specificity within this nematode species. More importantly, they show that host specificity can evolve rapidly when only one host is available for parasitization. Ecological conditions are such that natural populations ofH. aoronymphium may comprise numerous host races, lineages incapable of parasitizing the full range of host species. However, I argue that such host races are probably ephemeral and thus unlikely to persist long enough to undergo speciation.
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  • 35
    ISSN: 1617-4623
    Keywords: APRT ; Drosophila ; Nuclear matrix attachment site ; Dosage compensation ; Introns
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    Topics: Biology
    Notes: Abstract The Aprt locus of Drosophila encodes the structural gene for the purine salvage enzyme adenine phosphoribosyltransferase. Aprt is autosomal and enzyme activity is gene-dose-dependent in Drosophila melanogaster. However, Aprt is X-linked and dosage compensated in Drosophila pseudoobscura, as shown here. The Aprt genes of both Drosophila species contain a DNA sequence associated with nuclear matrix attachment sites and these Aprt sequences specifically bind to nuclear matrix in vitro. Putative promoter sequences positioned upstream of the predicted transcriptional start site in the two Aprt genes have a similar structure of direct repeats with an overlapping dyad symmetry, but the DNA sequence of these motifs is not conserved between the two species. Biological features in mutants of Aprt as well as natural variants suggest that dosage compensation of this gene in Drosophila pseudoobscura is due to a general control Mechanism on X-linked genes rather than a gene-specific mechanism.
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  • 36
    ISSN: 1617-4623
    Keywords: I factor ; LINE ; Drosophila ; Hybrid dysgenesis ; Maternal inheritance
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    Topics: Biology
    Notes: Abstract I factor is a functional LINE (long interspersed nucleotidic element) which is mobilized in the germ-line of dysgenic SF females during I-R hybrid dysgenesis. Such females are obtained when an oocyte from a reactive stock, devoid of I factors but characterized by a level of reactivity, i.e. its potential for hybrid dysgenesis, is fertilized by a spermatozoon from an I factor-containing inducer stock. In a previous paper we described the expression of an I factor-lacZ fusion. Expression was detected in the ovaries of reactive and dysgenic flies only. In this paper we show that this transgenic activity can be quantified and depends upon the maternally inherited reactivity. Reactivity is not just a permissive state and modifiers of the reactivity level such as heat treatment and ageing change the level of expression of our transgenic fusion accordingly. Moreover, ageing through generations has the same cumulative and reversible effect on both reactivity and I factor expression. Using our fusion as a test for reactivity we show that the silencing of I factor after its introduction into a reactive genome may not be established in a single generation.
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  • 37
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    Molecular genetics and genomics 238 (1993), S. 437-443 
    ISSN: 1617-4623
    Keywords: Polytene chromosome ; Transformation ; Interband ; Drosophila
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    Topics: Biology
    Notes: Abstract Interband DNA of Drosophila melanogaster polytene chromosomes was studied using a novel approach based on the electron microscopic (EM) analysis of chromosome regions carrying DNA fragements of known molecular genetic composition, inserted by P element-mediated transformation. Insertion of such fragments predominantly into interbands makes it possible to clone interband DNA by constructing genomic libraries from transformed strains and probing them with the insert DNA. The transformed strain P[H-sp70:Adh](61C) has insertion in the 61 C7-8 interband on the left arm of chromosome 3. This DNA consists of part of the hsp70 gene promoter fused to the coding region of the Adh gene, and is flanked on either side by P element sequences. We constructed a genomic library from DNA of this strain and isolated a clone containing the insert and the interband DNA. Subsequently the genomic library of wild-type strain was probed with a subclone composed of interband DNA only. We have thus isolated a clone containing the entire native interband. 1289 by of interband DNA was sequenced and found to be AT-rich (53.4%) with numerous regions of overlapping direct and inverted repeats, regulatory sites, and two overlapping open reading frames (ORFs).
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  • 38
    ISSN: 1617-4623
    Keywords: Vg mutant ; Antifolates ; Dihydrofolate reductase ; Drosophila ; Nucleotide metabolism
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    Topics: Biology
    Notes: Abstract The vestigal (vg) gene encodes a nuclear protein which plays a major role in the formation of the wing of Drosophila. Resistance or sensitivity to aminopterin, an inhibitor of the dihydrofolate reductase enzyme in D. melanogaster, seems to be associated with a specific alteration in vg gene function. Wild-type and vg mutant strains selected for growth on increasing concentrations of aminopterin display changes in physiological and biochemical parameters such as viability on normal and aminopterin-containing media, duration of development, wing phenotype, dihydrofolate reductase activity, and cross-resistance to fluorodeoxyuridine (FUdR) and to methotrexate. Our results indicate that the mechanisms of resistance differ in the wild-type and mutant strains. The vg 83b27 mutant, in which the major part of intron 2 of the vg gene is deleted, is associated with a high rate of resistance to FUdR, an inhibitor of thymidylate synthetase. Moreover, vg 83b27/vg BGheterozygotes, which are wild type when grown on normal medium, display a strong vg phenotype when grown on aminopterin. Our results indicate a role for the vestigial locus in mediating resistance to inhibitors of dTMP synthesis.
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  • 39
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    Genetica 90 (1993), S. 201-215 
    ISSN: 1573-6857
    Keywords: micro-evolution ; Drosophila ; alcohol tolerance ; alcohol dehydrogenase ; ethanol
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    Topics: Biology
    Notes: Abstract The population ofDrosophila melanogaster inside the wine cellar of Chateau Tahbilk of Victoria, Australia was found by McKenzie and Parsons (1974) to have undergone microevolution for greater alcohol tolerance when compared to the neighboring population outside the cellar. This triggered additional studies at Tahbilk, and at other wine cellars throughout the world. The contributions and interactions of researchers and the development of ideas on the ecology and genetics of this unique experimental system are traced. Although the ADH-F/ADH-S polymorphism was found to be maintained by selection in the Tahbilk populations, the selection is not significantly associated with alcohol tolerance. The environment inside the Tahbilk wine cellar is not as rich in ethanol as was originally anticipated, and selection that affects the alcohol dehydrogenase polymorphism may be more concerned with the relative efficiency with which ethanol is used as a nutrient byD. melanogaster. The synthesis and modification of lipids, particularly in membranes, appears to be important to alcohol tolerance. The studies of the Tahbilk population are at a crossroad. New experimental approaches promise to provide the keys to the selection that maintains the alcohol dehydrogenase polymorphism, and to factors that are important to alcohol tolerance and stress adaptation. From these research foundations at Tahbilk very significant contributions to our future understanding of the genetic processes of evolution can be made.
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  • 40
    ISSN: 1573-6857
    Keywords: aging ; extended longevity ; genetics of aging ; Drosophila ; gene-environment interactions ; gene regulation ; antioxidants
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  • 41
    ISSN: 1573-6857
    Keywords: superoxide dismutase ; aging ; Drosophila ; evolutionary genetics ; senescence
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    Notes: Abstract The effects of superoxide dismutase on aging were tested using two differt experimental approaches. In the first, replicated populations with postponed aging were compared with their controls for frequencies of electrophoretic alleles at the SOD locus. Populations with postponed aging had consistently greater frequencies of the allele coding for more active SOD protein. This allele was not part of a segregating inversion polymorphism. The second experimental approach was the extraction ofSOD alleles from different natural populations followed by the construction of differentSOD genotypes on hybrid genetic backgrounds. This procedure did not uncover any statistical effect ofSOD genotype on hybrid genetic backgrounds. This effects on longevity and fecundity due to the family from which a particularSOD genotype was derived. To detect the effects ofSOD genotypes on longevity with high probability would require a ten-fold increase in the number of families used.
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  • 42
    ISSN: 1573-6857
    Keywords: Drosophila ; esterase 6 ; interspecific sequence comparison ; protein evolution ; regulatory evolution
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    Topics: Biology
    Notes: Abstract Esterase 6 (Est-6/EST6) is the major β-carboxylesterase inD. melanogaster and its siblingsD. simulans andD. mauritiana. It is expressed in several tissues but its major site of expression is the sperm ejaculatory duct of the adult male. Although EST6 activity affects reproductive fitness, there are high levels of electrophoretic and activity polymorphism, at least withinD. melanogaster andD. simulans. Here we present the nucleotide sequences of anEst-6 allele and its flanking regions from each ofD. simulans andD. mauritiana and compare them with the publishedD. melanogaster sequences. As might be expected, replacement sites are significantly less divergent than exon silent sites in all comparisons, suggesting that selection is acting to maintain EST6 structure and function among the three species. Nevertheless, the ratio of the levels of replacement to silent site divergence is still much higher forEst-6 than for seven of ten other genes (including both isozyme-coding loci) for which comparable data have been published for these species. This is consistent with the high levels of EST6 electrophoretic polymorphism withinD. melanogaster andD. simulans and implies that selective constraints against amino acid change are relatively weak for EST6. By contrast, comparisons involving promotor sequences show that the level of divergence in the first 350bp 5′ of the gene is significantly lower than those for four of the six other loci for which comparable data have been published for these species. In particular, there are two perfectly conserved stretches (−1 to −158bp and −219 to −334bp) each over 100bp long included in this 350bp region. Thus the data suggest a relatively low level of selective constraint on the amino acid sequence of EST6 but a relatively high level of constraint on sequences affecting aspects of its expression.
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  • 43
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    Genetica 90 (1993), S. 157-163 
    ISSN: 1573-6857
    Keywords: cell cycle, development ; Drosophila ; embryogenesis ; proliferation
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    Notes: Abstract The zygotic expression of only a fewDrosophila genes is known to be required for completion of the normal embryonic mitoses. Molecular genetic analyses of these genes reveal that they fall into two classes, those whose mRNA levels are regulated in a stage and/or tissue-specific fashion to control cell cycle events during embryogenesis, and those in which, in the absence of functional zygotic expression, the maternal mRNA contribution does not provide sufficient product to complete the normal embryonic mitoses. Genes that comprise the first class are involved in the developmental control of the cell cycle, while those of the second class identify components of the cell cycle machinery.
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  • 44
    ISSN: 1573-6857
    Keywords: Drosophila ; stambh A ; paralysis ; embryonic lethal ; neural hypertrophy
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    Notes: Abstract The mutantstambhA 1 (2–56.8) ofDrosophila melanogaster was identified as a reversible temperature sensitive adult and larval paralytic. We have (i) isolated and analysed phenotypes of one new homozygous viable paralytic allele and two recessive unconditional embryonic lethal alleles ofstmA and (ii) studied the interaction of the viable paralytic alleles with ts paralytic mutantsnap ts1 (2–55.2) andpara ts1 (1–53.9). The homozygous viable paralytic allelesstmA 2 andstmA 1 are semi dominant neomorphs. The lethal allelesstmA 12 andstmA 7 appear to be amorphs. Unhatched embryos expressing lethalstmA alleles showed hypotrophy of the anterior dorsal cuticle overlying the brain with a concomitant hypertrophy of the anterior dorsal neurogenic region (the brain). The ventral cuticle was poorly differentiated, and the ventral nerve chord showed mild hypertrophy and poor organisation. The epidermal cells in 12–13 h old embryos did not show the normal palisade layer arrangement. These phenotypes are similar to mutant phenotypes of the neurogenic class of genes whose wild type functions are necessary for intercellular communication. The allelesstmA 1 andstmA 2 do not appear to interact with the paralytic mutantsnap ts1 orpara ts1 in double mutant combinations. On the basis of our results it is proposed thatstmA may belong to the neurogenic class of genes.
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  • 45
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    Genetica 90 (1993), S. 239-268 
    ISSN: 1573-6857
    Keywords: Drosophila ; esterases ; multigene families ; structure function models
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    Topics: Biology
    Notes: Abstract Over 30 carboxylester hydrolases have been identified inD. melanogaster. Most are classified as acetyl, carboxyl or cholinesterases. Sequence similarities among most of the carboxyl and all the cholinesterases so far characterised fromD. melanogaster and other eukaryotes justify recognition of a carboxyl/cholinesterase multigene family. This family shows minimal sequence similarities with other esterases but crystallographic data for a few non-drosophilid enzymes show that the family shares a distinctive overall structure with some other carboxyl and aryl esterases, so they are all put in one superfamily of /β hydrolases. Fifteen esterase genes have been mapped inD. melanogaster and twelve are clustered at two chromosomal sites. The constitution of each cluster varies acrossDrosophila species but two carboxyl esterases in one cluster are sufficiently conserved that their homologues can be identified among enzymes conferring insecticide resistance in other Diptera. Sequence differences between two other esterases, the EST6 carboxyl esterase and acetylcholinesterase, have been interpreted against the consensus super-secondary structure for the carboxyl/cholinesterase multigene family; their sequence differences are widely dispersed across the structure and include substantial divergence in substrate binding sites and the active site gorge. This also applies when EST6 is compared across species where differences in its expression indicate a difference in function. However, comparisons within and among species where EST6 expression is conserved show that many aspects of the predicted super-secondary structure are tightly conserved. Two notable exceptions are a pair of polymorphisms in the substrate binding site of the enzyme inD. melanogaster. These polymorphisms are associated with differences in substrate interactionsvitro} and demographic data indicate that the alternative forms are not selectively equivalentin vivo.
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  • 46
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    Genetica 91 (1993), S. 111-125 
    ISSN: 1573-6857
    Keywords: Drosophila ; evolution ; reproduction ; senescence ; sperm competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations ofDrosophila melanogaster that had been subjected to long-term selection favoring either delayed or rapid senescence were compared with respect to age-specific components of male reproductive success involving sperm competition. These components of reproductive success were divided into those related to sperm ‘defense’ (protection of sperm from other males), and into those related to sperm ‘offense’ (ability to mate with previously mated females and to displace the sperm of other males). Males were tested at four ages ranging from 1–2d to 5–6 wk after eclosion. Several aspects of sperm defense capability showed clear evidence of senescent decline. Furthermore, males from populations selected for delayed senescence were superior to males from control (rapid senescence) populations with regard to components of sperm defense. The superiority of males from populations with delayed senescence either increased as a function of male age, or was present at all ages tested. These results indicate that the rate of reproductive senescence in maleD. melanogaster can be altered in predictable directions by artificial selection. There were no differences between selection regimes with regard to sperm offense, and most components of sperm offense did not show clear evidence of senescence. The improved late-age reproductive success of males from populations selected for delayed senescence did not appear to entail any cost or trade-off at early ages with respect to the reproductive traits examined in these experiments.
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  • 47
    ISSN: 1573-6857
    Keywords: lifespan ; elongation factor ; Drosophila ; life history evolution ; genetic manipulation ; tradeoffs ; genetic correlations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper summarizes three experiments on the genetic manipulation of fitness components involved in the evolution of lifespan through the introduction of an additional copy of the gene for elongation factor EF-1α into the genome ofDrosophila melanogaster. The first experiment checked a prior claim that enhanced expression of elongation factor increased the lifespan of virgin male fruitfies. It used inbred stocks; three treatment and three control lines were available. The second experiment put one treatment and one control insert into different positions on the third chromosome, then measured the influence of six genetic backgrounds on treatment effects in healthier flies. The third experiment put six treatment and six control inserts into the genetic background whose lifespan was most sensitive to the effects of treatment in the second experiment, then measured the influence of insert positions on treatment effects in healthy flies. The treatment never increased the lifespan of virgin males. It increased the lifespan of mated females in inbred flies reared to eclosion at 25°, reduced it in the positions experiment, and made no difference to lifespan in the backgrounds experiment. When it increased lifespan, it reduced fecundity. In inbred flies and in the positions experiment, the treatment reduced dry weight at eclosion of females. Marginal effects of gene substitutions on tradeoffs were measured directly. The results suggest that enhanced expression of elongation factor makes local changes within the bounds of tradeoffs that are given by a pre-existing physiological structure whose basic nature is not changed by the treatment.
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  • 48
    ISSN: 1573-6857
    Keywords: aging ; Drosophila ; electrophoresis ; evolution ; longevity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five populations ofDrosophila melanogaster that had been selected for postponed aging were compared with five control populations using two-dimensional protein gel electrophoresis. The goals of the study were to identify specific proteins associated with postponed aging and to survey the population genetics of the response to selection. A total of 321 proteins were resolvable per population; these proteins were scored according to their intensity. The resulting data were analyzed using resampling, combinatoric, and maximum parsimony methods. The analysis indicated that the populations with postponed aging were different from their controls with respect to specific proteins and with respect to the variation between populations. The populations selected for postponed aging were more heterogeneous between populations than were the control populations. Maximum parsimony trees separate the selected populations, as a group, from their controls, thereby exhibiting a homoplastic pattern.
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  • 49
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    Genetica 92 (1993), S. 1-22 
    ISSN: 1573-6857
    Keywords: alcohol dehydrogenase ; Drosophila ; evolution ; gene ; protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolutionary genetics embodies a broad research area that ranges from the DNA level to studies of genetic aspects in populations. In all cases the purpose is to determine the impact of genetic variation on evolutionary change. The broad range of evolutionary genetics requires the involvement of a diverse group of researchers: molecular biologists, (population) geneticists, biochemists, physiologists, ecologists, ethologists and theorists, each of which has its own insights and interests. For example, biochemists are often not concerned with the physiological function of a protein (with respect to pH, substrates, temperature, etc.), while ecologists, in turn, are often not interested in the biochemical-physiological aspects underlying the traits they study. This review deals with several evolutionary aspects of the Drosophila alcohol dehydrogenase gene-enzyme system, and includes my own personal viewpoints. I have tried to condense and integrate the current knowledge in this field as it has developed since the comprehensive review by van Delden (1982). Details on specific issues may be gained from Sofer and Martin (1987), Sullivan, Atkinson and Starmer (1990); Chambers (1988, 1991); Geer, Miller and Heinstra (1991); and Winberg and McKinley-McKee (1992).
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  • 50
    ISSN: 1573-6857
    Keywords: Drosophila ; meiosis ; recombination ; spermatogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two meiotic genes from natural populations are described. A female meiotic mutation,mei(1)g13, mapped to 17.4 on the X chromosome, causes nondisjunction of all homologs except for the fourth chromosomes. In addition, it reduces recombination by 10% in the homozygotes and causes 18% increased recombination in the heterozygotes. A male meiotic mutation,mei-1223 m144 , is located on the third chromosome. Although this mutation causes nondisjunction of all chromosomes, each chromosome pair exhibits a different nondisjunction frequency. Large variations in the sizes of the premature sperm heads observed in the homozygotes may reflect irregular meiotic pairing and the subsequent abnormal segregation, resulting in aneuploid chromosome complements.
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  • 51
    ISSN: 1573-6857
    Keywords: alternative splicing ; Drosophila ; dunce ; pleiotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The D. melanogaster dunce gene is involved in both the learning and memory processes of the fly. The gene encodes for a cAMP-specific phosphodiesterase, a function playing a central role in the regulation of the intracellular cAMP level. Molecular cloning of dunce has so far not been completely achieved, although it is known that the gene encodes a large set of RNAs and has a complex organization, extending for more than 140 kilobases and containing several genes within its introns. Here wer report the isolation and the characterization of 21/7, a cDNA clone representative of a novel dunce splicing pattern. The nucleotide sequence of this clone led to the identification of a dunce exon included in at least one transcript so far uncharacterized.
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  • 52
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    Genetica 91 (1993), S. 89-98 
    ISSN: 1573-6857
    Keywords: aging ; senescence ; lifespan ; survival ; Drosophila ; evolution ; fertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolutionary explanations of aging (or senescence) fall into two classes. First, organisms might have evolved the optimal life history, in which survival and fertility late in life are sacrificed for the sake of early reproduction or high pre-adult survival. Second, the life history might be depressed below this optimal compromise by the influx of deleterious mutations; since selection against late-acting mutations is weaker, deleterious mutations will impose a greater load on late life. We discuss ways in which these theories might be investigated and distinguished, with reference to experimental work withDrosophila. While genetic correlations between life history traits determine the immediate response to selection, they are hard to measure, and may not reflect the fundamental constraints on life history. Long term selection experiments are more likely to be informative. The third approach of using experimental manipulations suffers from some of the same problems as measures of genetic correlations; however, these two approaches may be fruitful when used together. The experimental results so far suggest that aging inDrosophila has evolved in part as a consequence of selection for an optimal life history, and in part as a result of accumulation of predominantly late-acting deleterious mutations. Quantification of these effects presents a major challenge for the future.
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  • 53
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    Behavior genetics 23 (1993), S. 99-104 
    ISSN: 1573-3297
    Keywords: Anesthesia ; photoresponse ; phototaxis ; relative light values ; behavior ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Five isofemale strains from each of four sympatric species,Drosophila immigrans, D. repleta, D. melanogaster, andD. affinis, were lightly anesthetized with ether, CO2, Flynap, or cold temperature. The photoresponse of each treatment group was measured in an open field and a Y-tube apparatus. Relative light values were compared with those of the unanesthetized control groups of each species, as well as among the different treatments themselves and among species. Significant differences between species were apparent for all treatments in the Y-tube and for all treatments except ether and CO2 in the open field. Response to anesthesia may differ between species due, in part, to their differing genotypes. Comparing treatment groups within species in the Y-tube design, all species exceptD. melanogaster showed significant differences between treatments. In the open field, onlyD. affinis was significantly affected. Particularly in the Y-tube, anesthetized flies generally differed significantly from the controls, indicating that the use of anesthesia during a behavioral study could cause deviations in behavior from that of normal unanesthetized flies.
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