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  • 1
    Keywords: GENE ; RELEASE ; DROSOPHILA-MELANOGASTER ; SITE-SPECIFIC RECOMBINATION ; TECHNOLOGY ; FLY CERATITIS-CAPITATA ; FRT/Flp ; FRUIT-FLY ; GENETIC-TRANSFORMATION ; HERMES ; HOBO ; Insect pest management ; MUSCA-DOMESTICA ; phiC31 integrase ; piggyBac ; PIGGYBAC ELEMENTS ; Sterile Insect Technique ; TRANSPOSABLE ELEMENT MARINER
    Abstract: Transposon-based vectors currently provide the most suitable gene transfer systems for insect germ-line transformation and are used for molecular improvement of the Sterile Insect Technique. However, the long time stability of genome-integrated transposon constructs depends on the absence of transposase activity that could remobilize the transposon-embedded transgenes. To achieve transgene stability transposon vectors are usually non-autonomous, lacking a functional transposase gene, and chosen so that endogenous or related transposon activities are not present in the host. Nevertheless, the non-autonomous transposon-embedded transgenes could become unstable by the unintended presence of a mobilizing transposase that may have been undetected or subsequently entered the host species by horizontal gene transfer. Since the field release of transgenic insects will present environmental concerns relating to large populations and high mobility, it will be important to ensure that transgene constructs are stably integrated for maintaining strain integrity and eliminating the possibility for unintentional transfer into the genome of another organism. Here we review efficient methods to delete or rearrange terminal repeat sequences of transposons necessary for their mobility, subsequent to their initial genomic integration. These procedures should prevent transposase-mediated remobilization of the transgenes, ensuring their genomic stability
    Type of Publication: Journal article published
    PubMed ID: 20844938
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  • 2
    Keywords: human ; CLONES ; GENE ; GENES ; GENOME ; HYBRIDIZATION ; RESOLUTION ; chromosome ; MOUSE ; IN-SITU ; genetics ; FUSION ; FISH ; REGION ; REGIONS ; EVOLUTION ; LOCALIZATION ; NETHERLANDS ; SEGMENTS ; FLUORESCENCE ; ORGANIZATION ; fluorescence in situ hybridization ; heredity ; molecular ; LIGHT ; GENOME ORGANIZATION ; HOMOLOGY ; analysis ; USA ; NOR ; SET ; NOV ; comparison ; mammals ; Bos taurus ; DEER ; Homo sapiens ; KARYOTYPES ; Muntiacus muntjak ; Muntiacus reevesi ; synteny ; VAGINALIS
    Abstract: The Indian muntjac (Muntiacus muntjak vaginalis) has a karyotype of 2n = 6 in the female and 2n = 7 in the male. The karyotypic evolution of Indian muntjac via extensive tandem fusions and several centric fusions are well documented by molecular cytogenetic studies mainly utilizing chromosome paints. To achieve higher resolution mapping, a set of 42 different genomic clones coding for 37 genes and the nucleolar organizer region were used to examine homologies between the cattle (2n = 60), human (2n = 46), Indian muntjac (2n = 6/7) and Chinese muntjac (2n = 46) karyotypes. These genomic clones were mapped by fluorescence in situ hybridization (FISH). Localization of genes on all three pairs of M. m. vaginalis chromosomes and on the acrocentric chromosomes of M. reevesi allowed not only the analysis of the evolution of syntenic regions within the muntjac genus but also allowed a broader comparison of synteny with more distantly related species, such as cattle and human, to shed more light onto the evolving genome organization
    Type of Publication: Journal article published
    PubMed ID: 18283540
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  • 3
    ISSN: 1573-6857
    Keywords: Drosophila ; glycerol-3-phosphate oxidase ; spatial variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Replicate mass-bred laboratory populations of D. melanogaster were derived from females collected in the Tahbilk winery cellar and from females collected outside but from within two kilometres of the cellar. When mitochondrial extracts from larvae were assayed for specific activity of glycerol-3-phosphate oxidase the cellar populations had levels only 50% of those from the outside area, confirming an earlier report of such a difference among isofemale lines derived from these same areas. This micro-spatial differentiation occurred when larvae were raised on a medium supplemented with both sucrose (5% w/v) and ethanol (4% v/v), known to effect high GPO activity, but was not detected when the larvae were raised on unsupplemented medium. A heritable basis for larval GPO activity variation was confirmed in a set of 32 isogenic second chromosome substitution lines and measured in a subset of 4 of these lines about 25 generations later. A reciprocal cross using two isogenic substitution lines with the highest and lowest activities suggested the difference was attributable to genes acting additively and that there were no maternal or paternal effects. The detection of a collection site difference in GPO enzyme activity in the isogenic lines suggests that polymorphic variation on the second chromosome is responsible for the differentiation at the winery. Variation in adult GPO activity did not show a dependence on the winery location from where the isogenic lines were derived nor was there an effect of line. Adult GPO activity was significantly higher than that detected in larval tissues and did not show a dependence on the sugar/ethanol level in the growth medium.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-6857
    Keywords: Grasshopper ; polymorphism ; Robertsonian translocation ; segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The meiotic behavior of Robertsonian heterozygotes of Dichroplus pratensis was analyzed in order to establish the nature of the fusion polymorphisms (stable or transient) that occur in the species. The range of fusion frequencies varies widely for each fusion studied and populations with extreme frequencies exist, which could indicate a tendency for the loss or fixation of a given rearrangement. Our results revealed that no significant correlation exists between orientation (convergent and non-convergent) in PMI and MI and fusion frequency, nor between aneuploidy and fusion frequency. Thus, orientation and segregation seem to be independent of the frequencies of the fusions, which also do not appear to affect severely the fertility of heterozygotes. Our data suggest that the polymorphisms are, at least, cytogenetically stable.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-6857
    Keywords: Behavior genetics ; larvae ; foraging ; mutants ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used Drosophila melanogaster larvae with different alleles at the foraging (for) locus in a variety of behavioral tests to evaluate normal muscle usage of rover and sitter phenotypes. The results show that sitter and lethal sitter alleles of for do not affect larval behavior through a mutation which affects larval muscle usage. In general the behavior of rovers and sitters differed on food but not on non-nutritive substrates. Rovers and sitters moved equally well on non-nutritive substrates, and measures such as the time to roll over and length of forward stride showed no significant strain differences. Larvae with different alleles at for did not differ in body length. Rovers took more strides, not longer ones, than sitters while on foraging substrates. We conclude that differences in larval locomotion during foraging found in larvae with different alleles at for can not be explained on the basis of muscle usage alone. It is more likely that for affects larval ability to perceive or respond to the foraging environment.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 85 (1992), S. 231-239 
    ISSN: 1573-6857
    Keywords: Allozymes ; bivalves ; enzyme activity ; overdominance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrophoretic examination of a natural population sample of 332 mussels (Mytilus trossulus) revealed ten active allozyme alleles for the octopine dehydrogenase (Odh) locus and a statistically significant (P〈0.005) departure from expected genotypic proportions caused by a deficiency of heterozygous genotypes. In vitro specific activity for octopine dehydrogenase (E.C. 1.5.1.11) was determined for 207 mussels representing 17 different Odh genotypes. Odh heterozygotes had an average specific activity that was 19% greater than that of apparently homozygous genotypes, a significant (P〈0.05) difference. Electrophoretic examination of a natural population sample of 209 oysters (Crassostrea virginica) revealed 23 active allozyme alleles for the leucine aminopeptidase-2 (Lap-2) locus and a non-significant (P〉0.05) deficiency of heterozygous genotypes. In vitro specific activity for leucine aminopeptidase (E.C. 3.4.-.-) was determined for 89 oysters representing 19 different Lap-2 genotypes. Lap-2 heterozygotes had an average specific activity that was 56% greater than that of homozygous genotypes, a significant (P〈0.0001) difference. Possible explanations for the apparent overdominance in enzyme specific activity and the deficiency of heterozygotes include null alleles, molecular imprinting and aneuploidy.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The karyotype of Cebuella pygmaea (2n=44) obtained by G-, C-banding, and NOR-staining is described. This species presents a heteromorphic C band in the intersticial region of the short arm of chromosome 2. The data obtained were compared with those previously described for the karyotypes of Callithrix jacchus and Callithrix emiliae. The three species differ in the amount and distribution of non-centromeric constitutive heterochromatin. The importance of the variation in constitutive heterochromatin for the phylogeny of the group is discussed. Comparison of the karyotypes in terms of G-banding patterns showed that C. pygmaea and C. emiliae differ from C. jacchus by a Robertsonian translocation and a paracentric inversion, whereas C. pygmaea and C. emiliae differ from each other by a reciprocal translocation between an acrocentric autosome and the short arm of the submetacentric chromosomes that distinguishes their karyotypes from that of C. jacchus. The possible evolutionary paths followed by the karyotypes of the three species are discussed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Defective (nonautonomous) copies of transposable elements are relatively common in the genomes of eukaryotes but less common in the genomes of prokaryotes. With regard to transposable elements that exist exclusively in the form of DNA (nonretroviral transposable elements), nonautonomous elements may play a role in the regulation of transposition. In prokaryotes, plasmid-mediated horizontal transmission probably imposes a selection against nonautonomous elements, since nonautonomous elements are incapable of mobilizing themselves. The lower relative frequency of nonautonomous elements in prokaryotes may also retlect the coupling of transcription and translation, which may bias toward the cis activation of transposition. The cis bias we suggest need not be absolute in order to militate against the long-term maintenance of prokaryotic elements unable to transpose on their own. Furthermore, any cis bias in transposition would also decrease the opportunity for trans repression of transposition by nonautonomous elements.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evidence from in situ hybridizations of DNA from the transposable element hobo to polytene salivary gland chromosome squashes reveals that hobo occupies both cytological breakpoints of three of four endemic inversions sampled from natural populations of Drosophila melanogaster in the Hawaiian islands. The fourth endemic inversion has a single hobo insert at one breakpoint. Cosmopolitan inversions on the same chromosomes do not show this association. Frequencies of both endemic and cosmopolitan inversions in Hawaiian populations fall in ranges typical for natural populations of D. melanogaster sampled worldwide, suggesting that these results may be typical of other regions besides Hawaii. This appears to be the first direct demonstration that transposable elements are responsible for causing specific rearrangements found in nature; consequently, it is also the first direct demonstration that chromosome rearrangements can arise in nature in a manner predicted by results of hybrid dysgenic crosses in the laboratory. Possible population genetic and evolutionary consequences are discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 86 (1992), S. 143-154 
    ISSN: 1573-6857
    Keywords: Aging ; Drosophila melanogaster ; lifespan ; mutation ; P DNA elements ; somatic cells ; transpositions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As an initial study of the influence of transposable DNA elements on life history traits, and as a model system for estimating the impact of somatic genetic damage on longevity, the effect of P DNA element movement in somatic cells on adult lifespan was measured in Drosophila melanogaster males. Lifespan was significantly reduced in males that contained the somatically active P[ry+ Δ2–3](99B) element and 17, 4, 3, but not just a single P element. Furthermore, there appears to be a direct correlation between the number of transposing P elements and the amount of lifespan reduction. This reduction in lifespan observed in males with somatically active P elements is probably due to genetic damage in embryos, larvae and pupae from P-element excisions and insertions, leading to changes in gene structure and regulation, chromosome breakage, and subsequent cell death in adults. This hypothesis is supported in this study by a significant increase in recessive sex-linked lethal mutations in the same males that had reduced lifespans and by the previous observation of chromosome breakage in somatic cells of similar males. The evolutionary implications of these results are discussed, including the possible influence of somatic DNA transpositions on fitness and other life history traits.
    Type of Medium: Electronic Resource
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