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  1. Book ; Online: Repetitive DNA Sequences

    Clark, Andrew G. / Barbash, Daniel A. / Lower, Sarah E. / Dion-Côté, Anne-Marie

    2020  

    Abstract: Repetitive DNA is ubiquitous in eukaryotic genomes, and, in many species, comprises the bulk of the genome. Repeats include transposable elements that can self-mobilize and disperse around the genome, and tandemly-repeated satellite DNAs that increase in ...

    Abstract Repetitive DNA is ubiquitous in eukaryotic genomes, and, in many species, comprises the bulk of the genome. Repeats include transposable elements that can self-mobilize and disperse around the genome, and tandemly-repeated satellite DNAs that increase in copy number due to replication slippage and unequal crossing over. Despite their abundance, repetitive DNA is often ignored in genomic studies due to technical challenges in their identification, assembly, and quantification. New technologies and methods are now providing the unprecedented power to analyze repetitive DNAs across diverse taxa. Repetitive DNA is of particular interest because it can represent distinct modes of genome evolution. Some repetitive DNA forms essential genome structures, such as telomeres and centromeres, which are required for proper chromosome maintenance and segregation, whereas others form piRNA clusters that regulate transposable elements; thus, these elements are expected to evolve under purifying selection. In contrast, other repeats evolve selfishly and produce genetic conflicts with their host species that drive adaptive evolution of host defense systems. However, the majority of repeats likely accumulate in eukaryotes in the absence of selection due to mechanisms of transposition and unequal crossing over. Even these neutral repeats may indirectly influence genome evolution as they reach high abundance. In this Special Issue, the contributing authors explore these questions from a range of perspectives
    Keywords Science (General) ; Biology (General) ; Genetics
    Size 1 electronic resource (206 pages)
    Publisher MDPI - Multidisciplinary Digital Publishing Institute
    Document type Book ; Online
    Note English ; Open Access
    HBZ-ID HT020480893
    ISBN 9783039283668 ; 9783039283675 ; 3039283669 ; 3039283677
    DOI 10.3390/books978-3-03928-367-5
    Database ZB MED Catalogue: Medicine, Health, Nutrition, Environment, Agriculture

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  2. Article ; Online: Stonewall prevents expression of ectopic genes in the ovary and accumulates at insulator elements in D. melanogaster.

    Zinshteyn, Daniel / Barbash, Daniel A

    PLoS genetics

    2022  Volume 18, Issue 3, Page(s) e1010110

    Abstract: Germline stem cells (GSCs) are the progenitor cells of the germline for the lifetime of an animal. In Drosophila, these cells reside in a cellular niche that is required for both their maintenance (self-renewal) and differentiation (asymmetric division ... ...

    Abstract Germline stem cells (GSCs) are the progenitor cells of the germline for the lifetime of an animal. In Drosophila, these cells reside in a cellular niche that is required for both their maintenance (self-renewal) and differentiation (asymmetric division resulting in a daughter cell that differs from the GSC). The stem cell-daughter cell transition is tightly regulated by a number of processes, including an array of proteins required for genome stability. The germline stem-cell maintenance factor Stonewall (Stwl) associates with heterochromatin, but its molecular function is poorly understood. We performed RNA-Seq on stwl mutant ovaries and found significant derepression of many transposon families but not heterochromatic genes. We also discovered inappropriate expression of multiple classes of genes. Most prominent are testis-enriched genes, including the male germline sex-determination switch Phf7, the differentiation factor bgcn, and a large testis-specific gene cluster on chromosome 2, all of which are upregulated or ectopically expressed in stwl mutant ovaries. Surprisingly, we also found that RNAi knockdown of stwl in somatic S2 cells results in ectopic expression of these testis genes. Using parallel ChIP-Seq and RNA-Seq experiments in S2 cells, we discovered that Stwl localizes upstream of transcription start sites and at heterochromatic sequences including repetitive sequences associated with telomeres. Stwl is also enriched at bgcn, suggesting that it directly regulates this essential differentiation factor. Finally, we identify Stwl binding motifs that are shared with known insulator binding proteins. We propose that Stwl affects gene regulation, including repression of male transcripts in the female germline, by binding insulators and establishing chromatin boundaries.
    MeSH term(s) Animals ; Cell Differentiation ; DNA-Binding Proteins/genetics ; DNA-Binding Proteins/metabolism ; Drosophila Proteins/genetics ; Drosophila Proteins/metabolism ; Drosophila melanogaster/metabolism ; Female ; Germ Cells/metabolism ; Homeodomain Proteins/genetics ; Insulator Elements/genetics ; Male ; Ovary/metabolism ; Transcription Factors/genetics ; Transcription Factors/metabolism
    Chemical Substances DNA-Binding Proteins ; Drosophila Proteins ; Homeodomain Proteins ; PHF7 protein, Drosophila ; Transcription Factors ; stwl protein, Drosophila
    Language English
    Publishing date 2022-03-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2186725-2
    ISSN 1553-7404 ; 1553-7390
    ISSN (online) 1553-7404
    ISSN 1553-7390
    DOI 10.1371/journal.pgen.1010110
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Divergent selection on behavioural and chemical traits between reproductively isolated populations of Drosophila melanogaster.

    Jin, Bozhou / Barbash, Daniel A / Castillo, Dean M

    Journal of evolutionary biology

    2022  Volume 35, Issue 5, Page(s) 693–707

    Abstract: Speciation is driven by traits that can act to prevent mating between nascent lineages, including male courtship and female preference for male traits. Mating barriers involving these traits evolve quickly because there is strong selection on males and ... ...

    Abstract Speciation is driven by traits that can act to prevent mating between nascent lineages, including male courtship and female preference for male traits. Mating barriers involving these traits evolve quickly because there is strong selection on males and females to maximize reproductive success, and the tight co-evolution of mating interactions can lead to rapid diversification of sexual behaviour. Populations of Drosophila melanogaster show strong asymmetrical reproductive isolation that is correlated with geographic origin. Using strains that capture natural variation in mating traits, we ask two key questions: which specific male traits are females selecting, and are these traits under divergent sexual selection? These questions have proven extremely challenging to answer, because even in closely related lineages males often differ in multiple traits related to mating behaviour. We address these questions by estimating selection gradients for male courtship and cuticular hydrocarbons for two different female genotypes. We identify specific behaviours and particular cuticular hydrocarbons that are under divergent sexual selection and could potentially contribute to premating reproductive isolation. Additionally, we report that a subset of these traits are plastic; males adjust these traits based on the identity of the female genotype they interact with. These results suggest that even when male courtship is not fixed between lineages, ongoing selection can act on traits that are important for reproductive isolation.
    MeSH term(s) Animals ; Courtship ; Drosophila melanogaster/genetics ; Female ; Hydrocarbons ; Male ; Mating Preference, Animal ; Reproductive Isolation ; Sexual Behavior, Animal
    Chemical Substances Hydrocarbons
    Language English
    Publishing date 2022-04-12
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1465318-7
    ISSN 1420-9101 ; 1010-061X
    ISSN (online) 1420-9101
    ISSN 1010-061X
    DOI 10.1111/jeb.14007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Divergent selection on behavioural and chemical traits between reproductively isolated populations of Drosophila melanogaster

    Jin, Bozhou / Barbash, Daniel A. / Castillo, Dean M.

    Journal of evolutionary biology. 2022 May, v. 35, no. 5

    2022  

    Abstract: Speciation is driven by traits that can act to prevent mating between nascent lineages, including male courtship and female preference for male traits. Mating barriers involving these traits evolve quickly because there is strong selection on males and ... ...

    Abstract Speciation is driven by traits that can act to prevent mating between nascent lineages, including male courtship and female preference for male traits. Mating barriers involving these traits evolve quickly because there is strong selection on males and females to maximize reproductive success, and the tight co‐evolution of mating interactions can lead to rapid diversification of sexual behaviour. Populations of Drosophila melanogaster show strong asymmetrical reproductive isolation that is correlated with geographic origin. Using strains that capture natural variation in mating traits, we ask two key questions: which specific male traits are females selecting, and are these traits under divergent sexual selection? These questions have proven extremely challenging to answer, because even in closely related lineages males often differ in multiple traits related to mating behaviour. We address these questions by estimating selection gradients for male courtship and cuticular hydrocarbons for two different female genotypes. We identify specific behaviours and particular cuticular hydrocarbons that are under divergent sexual selection and could potentially contribute to premating reproductive isolation. Additionally, we report that a subset of these traits are plastic; males adjust these traits based on the identity of the female genotype they interact with. These results suggest that even when male courtship is not fixed between lineages, ongoing selection can act on traits that are important for reproductive isolation.
    Keywords Drosophila melanogaster ; coevolution ; courtship ; females ; genotype ; males ; provenance ; reproductive isolation ; reproductive success ; sexual selection
    Language English
    Dates of publication 2022-05
    Size p. 693-707.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1465318-7
    ISSN 1420-9101 ; 1010-061X
    ISSN (online) 1420-9101
    ISSN 1010-061X
    DOI 10.1111/jeb.14007
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Testing a candidate meiotic drive locus identified by pool sequencing.

    Barbash, Daniel A / Jin, Bozhou / Wei, Kevin H C / Dion-Côté, Anne-Marie

    G3 (Bethesda, Md.)

    2023  Volume 13, Issue 11

    Abstract: Meiotic drive biases the transmission of alleles in heterozygous individuals, such that Mendel's law of equal segregation is violated. Most examples of meiotic drive have been discovered over the past century based on causing sex ratio distortion or the ... ...

    Abstract Meiotic drive biases the transmission of alleles in heterozygous individuals, such that Mendel's law of equal segregation is violated. Most examples of meiotic drive have been discovered over the past century based on causing sex ratio distortion or the biased transmission of easily scoreable genetic markers that were linked to drive alleles. More recently, several approaches have been developed that attempt to identify distortions of Mendelian segregation genome wide. Here, we test a candidate female meiotic drive locus in Drosophila melanogaster, identified previously as causing a ∼54:46 distortion ratio using sequencing of large pools of backcross progeny. We inserted fluorescent visible markers near the candidate locus and scored transmission in thousands of individual progeny. We observed a small but significant deviation from the Mendelian expectation; however, it was in the opposite direction to that predicted based on the original experiments. We discuss several possible causes of the discrepancy between the 2 approaches, noting that subtle viability effects are particularly challenging to disentangle from potential small-effect meiotic drive loci. We conclude that pool sequencing approaches remain a powerful method to identify candidate meiotic drive loci but that genotyping of individual progeny at early developmental stages may be required for robust confirmation.
    MeSH term(s) Humans ; Animals ; Female ; Drosophila melanogaster/genetics ; Heterozygote ; Meiosis/genetics
    Language English
    Publishing date 2023-09-27
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural
    ZDB-ID 2629978-1
    ISSN 2160-1836 ; 2160-1836
    ISSN (online) 2160-1836
    ISSN 2160-1836
    DOI 10.1093/g3journal/jkad225
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Adaptive evolution among cytoplasmic piRNA proteins leads to decreased genomic auto-immunity.

    Wang, Luyang / Barbash, Daniel A / Kelleher, Erin S

    PLoS genetics

    2020  Volume 16, Issue 6, Page(s) e1008861

    Abstract: In metazoan germlines, the piRNA pathway acts as a genomic immune system, employing small RNA-mediated silencing to defend host DNA from the harmful effects of transposable elements (TEs). Expression of genomic TEs is proposed to initiate self regulation ...

    Abstract In metazoan germlines, the piRNA pathway acts as a genomic immune system, employing small RNA-mediated silencing to defend host DNA from the harmful effects of transposable elements (TEs). Expression of genomic TEs is proposed to initiate self regulation by increasing the production of repressive piRNAs, thereby "adapting" piRNA-mediated control to the most active TE families. Surprisingly, however, piRNA pathway proteins, which execute piRNA biogenesis and enforce silencing of targeted sequences, evolve rapidly and adaptively in animals. If TE silencing is ensured through piRNA biogenesis, what necessitates changes in piRNA pathway proteins? Here we used interspecific complementation to test for functional differences between Drosophila melanogaster and D. simulans alleles of three adaptively evolving piRNA pathway proteins: Armitage, Aubergine and Spindle-E. In contrast to piRNA-mediated transcriptional regulators examined in previous studies, these three proteins have cytoplasmic functions in piRNA maturation and post-transcriptional silencing. Across all three proteins we observed interspecific divergence in the regulation of only a handful of TE families, which were more robustly silenced by the heterospecific piRNA pathway protein. This unexpected result suggests that unlike transcriptional regulators, positive selection has not acted on cytoplasmic piRNA effector proteins to enhance their function in TE repression. Rather, TEs may evolve to "escape" silencing by host proteins. We further discovered that D. simulans alleles of aub and armi exhibit enhanced off-target effects on host transcripts in a D. melanogaster background, as well as modest reductions in the efficiency of piRNA biogenesis, suggesting that promiscuous binding of D. simulans Aub and Armi proteins to host transcripts reduces their participation in piRNA production. Avoidance of genomic auto-immunity may therefore be a critical target of selection. Our observations suggest that piRNA effector proteins are subject to an evolutionary trade-off between defending the host genome from the harmful effect of TEs while also minimizing collateral damage to host genes.
    MeSH term(s) Alleles ; Animals ; Animals, Genetically Modified ; Autoimmunity/genetics ; Cytoplasm/genetics ; Cytoplasm/metabolism ; DNA Transposable Elements/genetics ; DNA Transposable Elements/immunology ; Drosophila Proteins/genetics ; Drosophila Proteins/immunology ; Drosophila Proteins/metabolism ; Drosophila melanogaster/genetics ; Drosophila melanogaster/immunology ; Drosophila melanogaster/metabolism ; Drosophila simulans/genetics ; Drosophila simulans/metabolism ; Evolution, Molecular ; Female ; Gene Expression Regulation/immunology ; Genome, Insect/genetics ; Genome, Insect/immunology ; Male ; Mutation ; RNA Interference/immunology ; RNA, Small Interfering/biosynthesis
    Chemical Substances DNA Transposable Elements ; Drosophila Proteins ; RNA, Small Interfering
    Language English
    Publishing date 2020-06-11
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2186725-2
    ISSN 1553-7404 ; 1553-7390
    ISSN (online) 1553-7404
    ISSN 1553-7390
    DOI 10.1371/journal.pgen.1008861
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Taming the Turmoil Within: New Insights on the Containment of Transposable Elements.

    Kelleher, Erin S / Barbash, Daniel A / Blumenstiel, Justin P

    Trends in genetics : TIG

    2020  Volume 36, Issue 7, Page(s) 474–489

    Abstract: Transposable elements (TEs) are mobile genetic parasites that can exponentially increase their genomic abundance through self-propagation. Classic theoretical papers highlighted the importance of two potentially escalating forces that oppose TE spread: ... ...

    Abstract Transposable elements (TEs) are mobile genetic parasites that can exponentially increase their genomic abundance through self-propagation. Classic theoretical papers highlighted the importance of two potentially escalating forces that oppose TE spread: regulated transposition and purifying selection. Here, we review new insights into mechanisms of TE regulation and purifying selection, which reveal the remarkable foresight of these theoretical models. We further highlight emergent connections between transcriptional control enacted by small RNAs and the contribution of TE insertions to structural mutation and host-gene regulation. Finally, we call for increased comparative analysis of TE dynamics and fitness effects, as well as host control mechanisms, to reveal how interconnected forces shape the differential prevalence and distribution of TEs across the tree of life.
    MeSH term(s) Animals ; DNA Transposable Elements/genetics ; Evolution, Molecular ; Humans ; Models, Genetic ; RNA Interference ; Selection, Genetic
    Chemical Substances DNA Transposable Elements
    Language English
    Publishing date 2020-05-27
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 619240-3
    ISSN 1362-4555 ; 0168-9525 ; 0168-9479
    ISSN (online) 1362-4555
    ISSN 0168-9525 ; 0168-9479
    DOI 10.1016/j.tig.2020.04.007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Rapid evolution at the Drosophila telomere: transposable element dynamics at an intrinsically unstable locus.

    McGurk, Michael P / Dion-Côté, Anne-Marie / Barbash, Daniel A

    Genetics

    2021  Volume 217, Issue 2

    Abstract: Drosophila telomeres have been maintained by three families of active transposable elements (TEs), HeT-A, TAHRE, and TART, collectively referred to as HTTs, for tens of millions of years, which contrasts with an unusually high degree of HTT interspecific ...

    Abstract Drosophila telomeres have been maintained by three families of active transposable elements (TEs), HeT-A, TAHRE, and TART, collectively referred to as HTTs, for tens of millions of years, which contrasts with an unusually high degree of HTT interspecific variation. While the impacts of conflict and domestication are often invoked to explain HTT variation, the telomeres are unstable structures such that neutral mutational processes and evolutionary tradeoffs may also drive HTT evolution. We leveraged population genomic data to analyze nearly 10,000 HTT insertions in 85  Drosophila melanogaster genomes and compared their variation to other more typical TE families. We observe that occasional large-scale copy number expansions of both HTTs and other TE families occur, highlighting that the HTTs are, like their feral cousins, typically repressed but primed to take over given the opportunity. However, large expansions of HTTs are not caused by the runaway activity of any particular HTT subfamilies or even associated with telomere-specific TE activity, as might be expected if HTTs are in strong genetic conflict with their hosts. Rather than conflict, we instead suggest that distinctive aspects of HTT copy number variation and sequence diversity largely reflect telomere instability, with HTT insertions being lost at much higher rates than other TEs elsewhere in the genome. We extend previous observations that telomere deletions occur at a high rate, and surprisingly discover that more than one-third do not appear to have been healed with an HTT insertion. We also report that some HTT families may be preferentially activated by the erosion of whole telomeres, implying the existence of HTT-specific host control mechanisms. We further suggest that the persistent telomere localization of HTTs may reflect a highly successful evolutionary strategy that trades away a stable insertion site in order to have reduced impact on the host genome. We propose that HTT evolution is driven by multiple processes, with niche specialization and telomere instability being previously underappreciated and likely predominant.
    MeSH term(s) Animals ; DNA Transposable Elements ; Drosophila melanogaster ; Evolution, Molecular ; Genomic Instability ; Polymorphism, Genetic ; Recombination, Genetic ; Telomere/genetics
    Chemical Substances DNA Transposable Elements
    Language English
    Publishing date 2021-02-24
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2167-2
    ISSN 1943-2631 ; 0016-6731
    ISSN (online) 1943-2631
    ISSN 0016-6731
    DOI 10.1093/genetics/iyaa027
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Testing the Drosophila maternal haploid gene for functional divergence and a role in hybrid incompatibility.

    Castillo, Dean M / McCormick, Benjamin / Kean, Connor M / Natesan, Sahana / Barbash, Daniel A

    G3 (Bethesda, Md.)

    2022  Volume 12, Issue 9

    Abstract: Crosses between Drosophila simulans females and Drosophila melanogaster males produce viable F1 sons and poorly viable F1 daughters. Unlike most hybrid incompatibilities, this hybrid incompatibility violates Haldane's rule, the observation that ... ...

    Abstract Crosses between Drosophila simulans females and Drosophila melanogaster males produce viable F1 sons and poorly viable F1 daughters. Unlike most hybrid incompatibilities, this hybrid incompatibility violates Haldane's rule, the observation that incompatibilities preferentially affect the heterogametic sex. Furthermore, it has a different genetic basis than hybrid lethality in the reciprocal cross, with the causal allele in Drosophila melanogaster being a large species-specific block of complex satellite DNA on its X chromosome known as the 359-bp satellite, rather than a protein-coding locus. The causal allele(s) in Drosophila simulans are unknown but likely involve maternally expressed genes or factors since the F1 females die during early embryogenesis. The maternal haploid (mh) gene is an intriguing candidate because it is expressed maternally and its protein product localizes to the 359-bp repeat. We found that this gene has diverged extensively between Drosophila melanogaster and Drosophila simulans. This observation led to the hypothesis that Drosophila melanogaster mh may have coevolved with the 359-bp repeat and that hybrid incompatibility thus results from the absence of a coevolved mh allele in Drosophila simulans. We tested for the functional divergence of mh by creating matched transformants of Drosophila melanogaster and Drosophila simulans orthologs in both Drosophila melanogaster and Drosophila simulans strains. Surprisingly, we find that Drosophila simulans mh fully complements the female sterile phenotype of Drosophila melanogaster mh mutations. Contrary to our hypothesis, we find no evidence that adding a Drosophila melanogaster mh gene to Drosophila simulans increases hybrid viability.
    MeSH term(s) Animals ; Drosophila/genetics ; Drosophila melanogaster/genetics ; Drosophila simulans/genetics ; Female ; Genes, Lethal ; Haploidy ; Hybridization, Genetic ; Male
    Language English
    Publishing date 2022-06-10
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2629978-1
    ISSN 2160-1836 ; 2160-1836
    ISSN (online) 2160-1836
    ISSN 2160-1836
    DOI 10.1093/g3journal/jkac177
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Moving Speciation Genetics Forward: Modern Techniques Build on Foundational Studies in

    Castillo, Dean M / Barbash, Daniel A

    Genetics

    2017  Volume 207, Issue 3, Page(s) 825–842

    Abstract: The question of how new species evolve has been examined at every level, from macroevolutionary patterns of diversification to molecular population genetic analyses of specific genomic regions between species pairs. ...

    Abstract The question of how new species evolve has been examined at every level, from macroevolutionary patterns of diversification to molecular population genetic analyses of specific genomic regions between species pairs.
    MeSH term(s) Animals ; Drosophila/genetics ; Genetic Speciation ; Genetics, Population/methods ; Reproductive Isolation
    Language English
    Publishing date 2017-10-31
    Publishing country United States
    Document type Journal Article ; Review ; Research Support, N.I.H., Extramural
    ZDB-ID 2167-2
    ISSN 1943-2631 ; 0016-6731
    ISSN (online) 1943-2631
    ISSN 0016-6731
    DOI 10.1534/genetics.116.187120
    Database MEDical Literature Analysis and Retrieval System OnLINE

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