The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Wolfgang Hennig - One of the best experts on this subject based on the ideXlab platform.
-
transcription of gypsy elements in a y chromosome male fertility gene of Drosophila hydei
Genetics, 1996Co-Authors: Ron Hochstenbach, Harry R Harhangi, Karin Schouren, Petra Bindels, Ron Suijkerbuijk, Wolfgang HennigAbstract:We have found that defective gypsy retrotransposons are a major constituent of the lampbrush loop pair Nooses in the short arm of the Y chromosome of Drosophila hydei. The loop pair is formed by male fertility gene Q during the primary spermatocyte stage of spermatogenesis, each loop being a single transcription unit with an estimated length of 260 kb. Using fluorescent in situ hybridization, we show that throughout the loop transcripts gypsy elements are interspersed with blocks of a tandemly repetitive Y-specific DNA sequence, ay1. Nooses transcripts containing both sequence types show a wide size range on Northern blots, do not migrate to the cytoplasm, and are degraded just before the first meiotic division. Only one strand of ay1 and only the coding strand of gypsy can be detected in the loop transcripts. However, as cloned genomic DNA fragments also display opposite orientations of ay1 and gypsy, such DNA sections cannot be part of the Nooses. Hence, they are most likely derived from the flanking heterochromatin. The direction of transcription of ay1 and gypsy thus appears to be of a functional significance.
-
structure and expression of histone h3 3 genes in Drosophila melanogaster and Drosophila hydei
Genome, 1995Co-Authors: Anna Akhmanova, H Kremer, Petra Bindels, Jie Xu, Koos Miedema, Wolfgang HennigAbstract:We demonstrate that in Drosophila melanogaster the histone H3.3 replacement variant is encoded by two genes, H3.3A and H3.3B. We have isolated cDNA clones for H3.3A and cDNA and genomic clones for H3.3B. The genes encode exactly the same protein but are widely divergent in their untranslated regions (UTR). Both genes are expressed in embryos and adults; they are expressed in the gonads as well as in somatic tissues of the flies. However, only one of them, H3.3A, shows strong testes expression. The 3′ UTR of the H3.3A gene is relatively short (~250 nucleotides (nt)). H3.3B transcripts can be processed at several polyadenylation sites, the longest with a 3′ UTR of more than 1500 nt. The 3′ processing sites, preferentially used in the gonads and somatic tissues, are different. We have also isolated the Drosophila hydei homologues of the two H3.3 genes. They are quite similar to the D. melanogaster genes in their expression patterns. However, in contrast to their vertebrate counterparts, which are highly cons...
-
degenerating gypsy retrotransposons in a male fertility gene on the y chromosome of Drosophila hydei
Journal of Molecular Evolution, 1994Co-Authors: Ron Hochstenbach, Harry R Harhangi, Karin Schouren, Wolfgang HennigAbstract:During the evolution of the Y chromosome of Drosophila hydei, retrotransposons became incorporated into the lampbrush loop pairs formed by several of the male fertility genes on this chromosome. Although insertions of retrotransposons are involved in many spontaneous mutations, they do not affect the functions of these genes. We have sequenced gypsy elements that are expressed as constituents of male fertility gene Q in the lampbrush loop pair Nooses. We find that these gypsy elements are all truncated and specifically lost those sequences that may interfere with the continuity of lampbrush loop transcription. Only defective coding regions are found within the loop. Gypsy is not transcribed in loops of many other Drosophila species harboring the family. These results suggest that any contribution of gypsy to the function of male fertility gene Q does not depend on a conserved DNA sequence.
-
spermatogenesis of Drosophila hydei
International Review of Cytology-a Survey of Cell Biology, 1990Co-Authors: Wolfgang Hennig, H KremerAbstract:Publisher Summary This chapter describes the spermatogenesis of Drosophila hydei . The primary spermatocyte nuclei of D. hydei species display prominent intranuclear structures that are identified as lampbrush loops formed by the male fertility gene. The male germ cell differentiation in D. hydei closely resembles that of D. melanogaster . The chapter discusses the genetic background of Drosophila spermatogenesis and reviews the possible experimental approaches, relating this background to known mutants and to other data on spermatogenesis. The developing germ cells are found in their developmental sequential order within the testicular tubes. The testis-specific β 2 -tubulin emphasizes the power of the combination of genetic with molecular studies. Antisera induced against testis proteins or other proteins known to be expressed in the male germ line are used to recover clones from cDNA libraries in immunoscreens. The chapter also discusses future approaches for the dissection of spermatogenesis by molecular, genetic, and cytological methods.
Daisuke Kageyama - One of the best experts on this subject based on the ideXlab platform.
-
natural variation in population densities and vertical transmission rates of a spiroplasma endosymbiont in Drosophila hydei
Symbiosis, 2013Co-Authors: Ryu Osaka, Daisuke Kageyama, Temma Ichizono, Masashi Nomura, Masayoshi WatadaAbstract:A bacterium belonging to the genus Spiroplasma, an endosymbiont of the fly Drosophila hydei, is vertically transmitted through host egg cytoplasm. To infer vertical transmission rates of Spiroplasma in natural populations of D. hydei, the infection status of Spiroplasma was examined for offspring produced by Spiroplasma-positive females that were collected in two geographical populations. In both populations, nearly half of the broods consisted of only infected offspring. Infection frequencies of the rest of the broods ranged from 0.364 to 0.975. Quantitative PCR demonstrated that the Spiroplasma titers in the whole body of wild-caught females were highly variable (1.81 × 106–5.60 × 108 cells per insect). Contrary to our expectations, however, the Spiroplasma titers did not account for the variation in infection frequencies among offspring (i.e., vertical transmission rates). These results suggest that the spatial distribution of Spiroplasma, particularly in somatic tissues and germ tissues, is highly variable among host individuals, which may be caused by environmental stochasticity or some unknown effects.
-
population dynamics of a maternally transmitted spiroplasma infection in Drosophila hydei
Symbiosis, 2010Co-Authors: Ryu Osaka, Daisuke Kageyama, Masayoshi Watada, Masashi NomuraAbstract:A maternally-inherited spiroplasma endosymbiont of Drosophila hydei does not exert apparent phenotypes on both sexes of its host and is prevalent in natural populations of D. hydei. Our previous experiments using a laboratory stock of D. hydei revealed that low temperatures (such as 15°C and 18°C) dramatically lower the vertical transmission rates of this spiroplasma. Therefore, we hypothesized that, in temperate regions, the infection frequencies may decrease in cool seasons but increase in the summer season. To clarify the temporal population dynamics of the spiroplasma infection, D. hydei were collected from two Japanese populations in 2006–2008 from May to early August, representing the only period when a number of D. hydei are collectable in Japan, and examined for spiroplasma infection. Within each year, the frequency of spiroplasma infection fluctuated considerably in both populations. Consistent with our hypothesis, the infection frequency showed an increasing trend in both populations in 2007. However, the data in 2006 and 2008 did not show consistent patterns of increase. The population dynamics of spiroplasma infection may be affected but not critically determined by temperature. Moreover, despite the fluctuation within each year, the infection frequencies seemed to be stable across the years. The frequencies of spiroplasma infection in D. hydei populations may be stabilized by multiple factors. One of these factors may involve a context-dependent positive effect of spiroplasma on the fitness of D. hydei, as was recently observed in laboratory experiments.
-
prevalence of a non male killing spiroplasma in natural populations of Drosophila hydei
Applied and Environmental Microbiology, 2006Co-Authors: Daisuke Kageyama, Hisashi Anbutsu, Masayoshi Watada, Takahiro Hosokawa, Masakazu Shimada, Takema FukatsuAbstract:Male-killing phenotypes are found in a variety of insects and are often associated with maternally inherited endosymbiotic bacteria. In several species of Drosophila, male-killing endosymbionts of the genus Spiroplasma have been found at low frequencies (0.1 to 3%). In this study, spiroplasma infection without causing male-killing was shown to be prevalent (23 to 66%) in Japanese populations of Drosophila hydei. Molecular phylogenetic analyses showed that D. hydei was infected with a single strain of spiroplasma, which was closely related to male-killing spiroplasmas from other Drosophila species. Artificial-transfer experiments suggested that the spiroplasma genotype rather than the host genotype was responsible for the absence of the male-killing phenotype. Infection densities of the spiroplasma in the natural host, D. hydei, and in the artificial host, Drosophila melanogaster, were significantly lower than those of the male-killing spiroplasma NSRO, which was in accordance with the hypothesis that a threshold infection density is needed for the spiroplasma-induced male-killing expression.
Patricia Adair Gowaty - One of the best experts on this subject based on the ideXlab platform.
-
microsatellite markers isolated from Drosophila hydei
Molecular Ecology Resources, 2009Co-Authors: Maureen B Peters, Cris Hagen, Brian D Snyder, Travis C Glenn, Patricia Adair GowatyAbstract:: We isolated and characterized 10 polymorphic microsatellite loci in Drosophila hydei. The number of alleles per locus ranged from 3 to 8 (N = 23 individuals). Polymorphic information content ranged from 0.316 to 0.750 and observed heterozygosity from 0.261 to 0.913. These markers will be valuable in studies of sexual selection and parental investment in D. hydei.
Charalambos Savakis - One of the best experts on this subject based on the ideXlab platform.
-
gene transfer into the medfly ceratitis capitata with a Drosophila hydei transposable element
Science, 1995Co-Authors: Thanasis G Loukeris, Ioannis Livadaras, Bruno Arca, Sophia Zabalou, Charalambos SavakisAbstract:Exogenous functional DNA was introduced into the germline chromosomes of the Mediterranean fruit fly (medfly) Ceratitis capitata with a germline transformation system based on the transposable element Minos from Drosophila hydei. Transformants were identified as phenotypic revertants of a white-eyed mutation carried by the recipient strain. Clusters of transformants were detected among the progeny of 390 individuals screened for germline transformation. Five independent and phenotypically active integration events were identified, in each of which a single copy of the transposon was inserted into a different site of the medfly genome. Molecular analysis indicates that they represent transposase-mediated insertions of the transposon into medfly chromosomes.
-
mobile minos elements from Drosophila hydei encode a two exon transposase with similarity to the paired dna binding domain
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Gerald H Franz, Thanasis G Loukeris, Georgia Dialektaki, Christopher R L Thompson, Charalambos SavakisAbstract:Abstract Elements related to the Tc1-like Minos mobile element have been cloned from Drosophila hydei and sequenced. Southern blot and sequence analyses show that (i) the elements are actively transposing in the Drosophila hydei germ line, (ii) they are characterized by a striking degree of sequence and size homogeneity, and (iii) like Tc1, they insert at a TA dinucleotide that is probably duplicated during the process. The nucleotide sequences of two elements, Minos-2 and Minos-3, differ at only one position from each other and contain two nonoverlapping open reading frames that are separated by a putative 60-nucleotide intron. The amino-terminal part of the Minos putative transposase shows sequence similarity to the paired DNA-binding domain. Forced transcription of a modified Minos element that was introduced into the Drosophila melanogaster germ line by P element-mediated transformation resulted in the production of accurately spliced polyadenylylated RNA molecules. It is proposed that Minos-2 and/or Minos-3 may encode an active transposase containing an amino-terminal DNA-binding domain that is distantly related to the paired DNA-binding domain.
Masayoshi Watada - One of the best experts on this subject based on the ideXlab platform.
-
natural variation in population densities and vertical transmission rates of a spiroplasma endosymbiont in Drosophila hydei
Symbiosis, 2013Co-Authors: Ryu Osaka, Daisuke Kageyama, Temma Ichizono, Masashi Nomura, Masayoshi WatadaAbstract:A bacterium belonging to the genus Spiroplasma, an endosymbiont of the fly Drosophila hydei, is vertically transmitted through host egg cytoplasm. To infer vertical transmission rates of Spiroplasma in natural populations of D. hydei, the infection status of Spiroplasma was examined for offspring produced by Spiroplasma-positive females that were collected in two geographical populations. In both populations, nearly half of the broods consisted of only infected offspring. Infection frequencies of the rest of the broods ranged from 0.364 to 0.975. Quantitative PCR demonstrated that the Spiroplasma titers in the whole body of wild-caught females were highly variable (1.81 × 106–5.60 × 108 cells per insect). Contrary to our expectations, however, the Spiroplasma titers did not account for the variation in infection frequencies among offspring (i.e., vertical transmission rates). These results suggest that the spatial distribution of Spiroplasma, particularly in somatic tissues and germ tissues, is highly variable among host individuals, which may be caused by environmental stochasticity or some unknown effects.
-
population dynamics of a maternally transmitted spiroplasma infection in Drosophila hydei
Symbiosis, 2010Co-Authors: Ryu Osaka, Daisuke Kageyama, Masayoshi Watada, Masashi NomuraAbstract:A maternally-inherited spiroplasma endosymbiont of Drosophila hydei does not exert apparent phenotypes on both sexes of its host and is prevalent in natural populations of D. hydei. Our previous experiments using a laboratory stock of D. hydei revealed that low temperatures (such as 15°C and 18°C) dramatically lower the vertical transmission rates of this spiroplasma. Therefore, we hypothesized that, in temperate regions, the infection frequencies may decrease in cool seasons but increase in the summer season. To clarify the temporal population dynamics of the spiroplasma infection, D. hydei were collected from two Japanese populations in 2006–2008 from May to early August, representing the only period when a number of D. hydei are collectable in Japan, and examined for spiroplasma infection. Within each year, the frequency of spiroplasma infection fluctuated considerably in both populations. Consistent with our hypothesis, the infection frequency showed an increasing trend in both populations in 2007. However, the data in 2006 and 2008 did not show consistent patterns of increase. The population dynamics of spiroplasma infection may be affected but not critically determined by temperature. Moreover, despite the fluctuation within each year, the infection frequencies seemed to be stable across the years. The frequencies of spiroplasma infection in D. hydei populations may be stabilized by multiple factors. One of these factors may involve a context-dependent positive effect of spiroplasma on the fitness of D. hydei, as was recently observed in laboratory experiments.
-
prevalence of a non male killing spiroplasma in natural populations of Drosophila hydei
Applied and Environmental Microbiology, 2006Co-Authors: Daisuke Kageyama, Hisashi Anbutsu, Masayoshi Watada, Takahiro Hosokawa, Masakazu Shimada, Takema FukatsuAbstract:Male-killing phenotypes are found in a variety of insects and are often associated with maternally inherited endosymbiotic bacteria. In several species of Drosophila, male-killing endosymbionts of the genus Spiroplasma have been found at low frequencies (0.1 to 3%). In this study, spiroplasma infection without causing male-killing was shown to be prevalent (23 to 66%) in Japanese populations of Drosophila hydei. Molecular phylogenetic analyses showed that D. hydei was infected with a single strain of spiroplasma, which was closely related to male-killing spiroplasmas from other Drosophila species. Artificial-transfer experiments suggested that the spiroplasma genotype rather than the host genotype was responsible for the absence of the male-killing phenotype. Infection densities of the spiroplasma in the natural host, D. hydei, and in the artificial host, Drosophila melanogaster, were significantly lower than those of the male-killing spiroplasma NSRO, which was in accordance with the hypothesis that a threshold infection density is needed for the spiroplasma-induced male-killing expression.
