The Experts below are selected from a list of 6228 Experts worldwide ranked by ideXlab platform
Thomas R Buckley - One of the best experts on this subject based on the ideXlab platform.
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Assembling large genomes: analysis of the stick insect (Clitarchus hookeri) genome reveals a high repeat content and sex-biased genes associated with reproduction
BMC Genomics, 2017Co-Authors: Chen Wu, Ross N Crowhurst, Victoria G Twort, Richard D. Newcomb, Thomas R BuckleyAbstract:Background Stick insects (Phasmatodea) have a high incidence of Parthenogenesis and other alternative reproductive strategies, yet the genetic basis of reproduction is poorly understood. Phasmatodea includes nearly 3000 species, yet only the genome of Timema cristinae has been published to date. Clitarchus hookeri is a geographical parthenogenetic stick insect distributed across New Zealand. Sexual reproduction dominates in northern habitats but is replaced by Parthenogenesis in the south. Here, we present a de novo genome assembly of a female C. hookeri and use it to detect candidate genes associated with gamete production and development in females and males. We also explore the factors underlying large genome size in stick insects. Results The C. hookeri genome assembly was 4.2 Gb, similar to the flow cytometry estimate, making it the second largest insect genome sequenced and assembled to date. Like the large genome of Locusta migratoria , the genome of C. hookeri is also highly repetitive and the predicted gene models are much longer than those from most other sequenced insect genomes, largely due to longer introns. Miniature inverted repeat transposable elements (MITEs), absent in the much smaller T. cristinae genome, is the most abundant repeat type in the C. hookeri genome assembly. Mapping RNA-Seq reads from female and male gonadal transcriptomes onto the genome assembly resulted in the identification of 39,940 gene loci, 15.8% and 37.6% of which showed female-biased and male-biased expression, respectively. The genes that were over-expressed in females were mostly associated with molecular transportation, developmental process, oocyte growth and reproductive process; whereas, the male-biased genes were enriched in rhythmic process, molecular transducer activity and synapse. Several genes involved in the juvenile hormone synthesis pathway were also identified. Conclusions The evolution of large insect genomes such as L. migratoria and C. hookeri genomes is most likely due to the accumulation of repetitive regions and intron elongation. MITEs contributed significantly to the growth of C. hookeri genome size yet are surprisingly absent from the T. cristinae genome. Sex-biased genes identified from gonadal tissues, including genes involved in juvenile hormone synthesis, provide interesting candidates for the further study of flexible reproduction in stick insects.
Roisi Yves - One of the best experts on this subject based on the ideXlab platform.
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Sex ratio variations among years and breeding systems in a facultatively parthenogenetic termite
'Springer Science and Business Media LLC', 2019Co-Authors: Hellemans Simo, Fournie Denis, Hanus Robe, Roisi YvesAbstract:Some species of termites evolved an outstanding reproductive strategy called asexual queen succession (AQS), in which the primary queen is replaced by multiple parthenogenetically produced daughters (neotenics) that mate with the primary king. When the primary king is eventually replaced, this time by sexually produced neotenic king(s), sex-asymmetric inbreeding occurs and the queen’s genome is more transmitted than that of the king, thereby increasing the reproductive value of female dispersers, and female-biased population sex ratio is expected. Yet, the life cycle, the breeding system dynamics and AQS modalities differ between AQS species, thereby modifying the relative genetic contribution of primary reproductives in the colony and thus also the equilibrium sex ratio. We estimated colonial and population sex ratio over two consecutive dispersal periods in a French Guiana population of Cavitermes tuberosus (Termitinae) in which the founding queen may be replaced only after colony maturity, some neotenic females may be sexually produced, and some female dispersers arise through Parthenogenesis. Colonial sex ratio varied among colonies: primary-headed nests with higher within-nest relatedness produced more females than neotenic-headed nests with lower relatedness among individuals. Over the two dispersal periods, the population investment sex ratio fluctuated around 1:1, thereby confirming that AQS breeding system is not necessarily linked with female-biased sex ratio. The balanced alate sex ratio, combined with the occurrence of sexually produced neotenic queens, is possibly the outcome of a queen-king conflict between the primary reproductives.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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Widespread occurrence of asexual reproduction in higher termites of the Termes group (Termitidae: Termitinae)
'Springer Science and Business Media LLC', 2019Co-Authors: Hellemans Simo, Dolejšová Klára, Ja Křivánek, Fournie Denis, Hanus Robe, Roisi YvesAbstract:BackgroundA decade ago, the mixed reproductive strategy Asexual Queen Succession (AQS) was first described in termites. In AQS species, the workers, soldiers and dispersing reproductives are produced through sexual reproduction, while non-dispersing (neotenic) queens arise through automictic thelytokous Parthenogenesis, replace the founding queen and mate with the founding king. As yet, AQS has been documented in six species from three lineages of lower (Rhinotermitidae) and higher (Termitinae: Termes group and Syntermitinae) termites. Independent evolution of the capacity of thelytoky as a preadaptation to AQS is supported by different mechanisms of automixis in each of the three clades. These pioneering discoveries prompt the question on the extent of thelytoky and AQS in the diversified family of higher termites.ResultsHere, we investigated the capacity of thelytoky and occurrence of AQS in three species from the phylogenetic proximity of the neotropical AQS species Cavitermes tuberosus (Termitinae: Termes group): Palmitermes impostor, Spinitermes trispinosus, and Inquilinitermes inquilinus. We show that queens of all three species are able to lay unfertilized eggs, which undergo thelytokous Parthenogenesis (via gamete duplication as in C. tuberosus) and develop through the transitional stage of aspirants into replacement neotenic queens.ConclusionsThe breeding system in P. impostor is very reminiscent of that described in C. tuberosus and can be characterized as AQS. In the remaining two species, our limited data do not allow classifying the breeding system as AQS; yet, also in these species the thelytokous production of neotenic females appears to be a systematic element of reproductive strategies. It appears likely that the capacity of thelytokous Parthenogenesis evolved once in the Termes group, and may ultimately be found more widely, well beyond these Neotropical species.info:eu-repo/semantics/publishe
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Data from: Sex ratio variations among years and breeding systems in a facultatively parthenogenetic termite
2018Co-Authors: Hellemans Simo, Fournie Denis, Hanus Robe, Roisi YvesAbstract:Some species of termites evolved an outstanding reproductive strategy called asexual queen succession (AQS), in which the primary queen is replaced by multiple parthenogenetically produced daughters (neotenics) that mate with the primary king. When the primary king is eventually replaced, this time by sexually produced neotenic king(s), sex-asymmetric inbreeding occurs and the queen’s genome is more transmitted than that of the king, thereby increasing the reproductive value of female dispersers, and female-biased population sex ratio is expected. Yet, the life cycle, the breeding system dynamics and AQS modalities differ between AQS species, thereby modifying the relative genetic contribution of primary reproductives in the colony and thus also the equilibrium sex ratio. We estimated colonial and population sex ratio over two consecutive dispersal periods in a French Guiana population of Cavitermes tuberosus (Termitinae) in which the founding queen may be replaced only after colony maturity, some neotenic females may be sexually produced, and some female dispersers arise through Parthenogenesis. Colonial sex ratio varied among colonies: primary-headed nests with higher within-nest relatedness produced more females than neotenic-headed nests with lower relatedness among individuals. Over the two dispersal periods, the population investment sex ratio fluctuated around 1:1, thereby confirming that AQS breeding system is not necessarily linked with female biased sex ratio. The balanced alate sex ratio, combined with the occurrence of sexually produced neotenic queens, is possibly the outcome of a queen-king conflict between the primary reproductives
Chen Wu - One of the best experts on this subject based on the ideXlab platform.
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Assembling large genomes: analysis of the stick insect (Clitarchus hookeri) genome reveals a high repeat content and sex-biased genes associated with reproduction
BMC Genomics, 2017Co-Authors: Chen Wu, Ross N Crowhurst, Victoria G Twort, Richard D. Newcomb, Thomas R BuckleyAbstract:Background Stick insects (Phasmatodea) have a high incidence of Parthenogenesis and other alternative reproductive strategies, yet the genetic basis of reproduction is poorly understood. Phasmatodea includes nearly 3000 species, yet only the genome of Timema cristinae has been published to date. Clitarchus hookeri is a geographical parthenogenetic stick insect distributed across New Zealand. Sexual reproduction dominates in northern habitats but is replaced by Parthenogenesis in the south. Here, we present a de novo genome assembly of a female C. hookeri and use it to detect candidate genes associated with gamete production and development in females and males. We also explore the factors underlying large genome size in stick insects. Results The C. hookeri genome assembly was 4.2 Gb, similar to the flow cytometry estimate, making it the second largest insect genome sequenced and assembled to date. Like the large genome of Locusta migratoria , the genome of C. hookeri is also highly repetitive and the predicted gene models are much longer than those from most other sequenced insect genomes, largely due to longer introns. Miniature inverted repeat transposable elements (MITEs), absent in the much smaller T. cristinae genome, is the most abundant repeat type in the C. hookeri genome assembly. Mapping RNA-Seq reads from female and male gonadal transcriptomes onto the genome assembly resulted in the identification of 39,940 gene loci, 15.8% and 37.6% of which showed female-biased and male-biased expression, respectively. The genes that were over-expressed in females were mostly associated with molecular transportation, developmental process, oocyte growth and reproductive process; whereas, the male-biased genes were enriched in rhythmic process, molecular transducer activity and synapse. Several genes involved in the juvenile hormone synthesis pathway were also identified. Conclusions The evolution of large insect genomes such as L. migratoria and C. hookeri genomes is most likely due to the accumulation of repetitive regions and intron elongation. MITEs contributed significantly to the growth of C. hookeri genome size yet are surprisingly absent from the T. cristinae genome. Sex-biased genes identified from gonadal tissues, including genes involved in juvenile hormone synthesis, provide interesting candidates for the further study of flexible reproduction in stick insects.
Hellemans Simo - One of the best experts on this subject based on the ideXlab platform.
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Sex ratio variations among years and breeding systems in a facultatively parthenogenetic termite
'Springer Science and Business Media LLC', 2019Co-Authors: Hellemans Simo, Fournie Denis, Hanus Robe, Roisi YvesAbstract:Some species of termites evolved an outstanding reproductive strategy called asexual queen succession (AQS), in which the primary queen is replaced by multiple parthenogenetically produced daughters (neotenics) that mate with the primary king. When the primary king is eventually replaced, this time by sexually produced neotenic king(s), sex-asymmetric inbreeding occurs and the queen’s genome is more transmitted than that of the king, thereby increasing the reproductive value of female dispersers, and female-biased population sex ratio is expected. Yet, the life cycle, the breeding system dynamics and AQS modalities differ between AQS species, thereby modifying the relative genetic contribution of primary reproductives in the colony and thus also the equilibrium sex ratio. We estimated colonial and population sex ratio over two consecutive dispersal periods in a French Guiana population of Cavitermes tuberosus (Termitinae) in which the founding queen may be replaced only after colony maturity, some neotenic females may be sexually produced, and some female dispersers arise through Parthenogenesis. Colonial sex ratio varied among colonies: primary-headed nests with higher within-nest relatedness produced more females than neotenic-headed nests with lower relatedness among individuals. Over the two dispersal periods, the population investment sex ratio fluctuated around 1:1, thereby confirming that AQS breeding system is not necessarily linked with female-biased sex ratio. The balanced alate sex ratio, combined with the occurrence of sexually produced neotenic queens, is possibly the outcome of a queen-king conflict between the primary reproductives.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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Widespread occurrence of asexual reproduction in higher termites of the Termes group (Termitidae: Termitinae)
'Springer Science and Business Media LLC', 2019Co-Authors: Hellemans Simo, Dolejšová Klára, Ja Křivánek, Fournie Denis, Hanus Robe, Roisi YvesAbstract:BackgroundA decade ago, the mixed reproductive strategy Asexual Queen Succession (AQS) was first described in termites. In AQS species, the workers, soldiers and dispersing reproductives are produced through sexual reproduction, while non-dispersing (neotenic) queens arise through automictic thelytokous Parthenogenesis, replace the founding queen and mate with the founding king. As yet, AQS has been documented in six species from three lineages of lower (Rhinotermitidae) and higher (Termitinae: Termes group and Syntermitinae) termites. Independent evolution of the capacity of thelytoky as a preadaptation to AQS is supported by different mechanisms of automixis in each of the three clades. These pioneering discoveries prompt the question on the extent of thelytoky and AQS in the diversified family of higher termites.ResultsHere, we investigated the capacity of thelytoky and occurrence of AQS in three species from the phylogenetic proximity of the neotropical AQS species Cavitermes tuberosus (Termitinae: Termes group): Palmitermes impostor, Spinitermes trispinosus, and Inquilinitermes inquilinus. We show that queens of all three species are able to lay unfertilized eggs, which undergo thelytokous Parthenogenesis (via gamete duplication as in C. tuberosus) and develop through the transitional stage of aspirants into replacement neotenic queens.ConclusionsThe breeding system in P. impostor is very reminiscent of that described in C. tuberosus and can be characterized as AQS. In the remaining two species, our limited data do not allow classifying the breeding system as AQS; yet, also in these species the thelytokous production of neotenic females appears to be a systematic element of reproductive strategies. It appears likely that the capacity of thelytokous Parthenogenesis evolved once in the Termes group, and may ultimately be found more widely, well beyond these Neotropical species.info:eu-repo/semantics/publishe
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Data from: Sex ratio variations among years and breeding systems in a facultatively parthenogenetic termite
2018Co-Authors: Hellemans Simo, Fournie Denis, Hanus Robe, Roisi YvesAbstract:Some species of termites evolved an outstanding reproductive strategy called asexual queen succession (AQS), in which the primary queen is replaced by multiple parthenogenetically produced daughters (neotenics) that mate with the primary king. When the primary king is eventually replaced, this time by sexually produced neotenic king(s), sex-asymmetric inbreeding occurs and the queen’s genome is more transmitted than that of the king, thereby increasing the reproductive value of female dispersers, and female-biased population sex ratio is expected. Yet, the life cycle, the breeding system dynamics and AQS modalities differ between AQS species, thereby modifying the relative genetic contribution of primary reproductives in the colony and thus also the equilibrium sex ratio. We estimated colonial and population sex ratio over two consecutive dispersal periods in a French Guiana population of Cavitermes tuberosus (Termitinae) in which the founding queen may be replaced only after colony maturity, some neotenic females may be sexually produced, and some female dispersers arise through Parthenogenesis. Colonial sex ratio varied among colonies: primary-headed nests with higher within-nest relatedness produced more females than neotenic-headed nests with lower relatedness among individuals. Over the two dispersal periods, the population investment sex ratio fluctuated around 1:1, thereby confirming that AQS breeding system is not necessarily linked with female biased sex ratio. The balanced alate sex ratio, combined with the occurrence of sexually produced neotenic queens, is possibly the outcome of a queen-king conflict between the primary reproductives
Ross N Crowhurst - One of the best experts on this subject based on the ideXlab platform.
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Assembling large genomes: analysis of the stick insect (Clitarchus hookeri) genome reveals a high repeat content and sex-biased genes associated with reproduction
BMC Genomics, 2017Co-Authors: Chen Wu, Ross N Crowhurst, Victoria G Twort, Richard D. Newcomb, Thomas R BuckleyAbstract:Background Stick insects (Phasmatodea) have a high incidence of Parthenogenesis and other alternative reproductive strategies, yet the genetic basis of reproduction is poorly understood. Phasmatodea includes nearly 3000 species, yet only the genome of Timema cristinae has been published to date. Clitarchus hookeri is a geographical parthenogenetic stick insect distributed across New Zealand. Sexual reproduction dominates in northern habitats but is replaced by Parthenogenesis in the south. Here, we present a de novo genome assembly of a female C. hookeri and use it to detect candidate genes associated with gamete production and development in females and males. We also explore the factors underlying large genome size in stick insects. Results The C. hookeri genome assembly was 4.2 Gb, similar to the flow cytometry estimate, making it the second largest insect genome sequenced and assembled to date. Like the large genome of Locusta migratoria , the genome of C. hookeri is also highly repetitive and the predicted gene models are much longer than those from most other sequenced insect genomes, largely due to longer introns. Miniature inverted repeat transposable elements (MITEs), absent in the much smaller T. cristinae genome, is the most abundant repeat type in the C. hookeri genome assembly. Mapping RNA-Seq reads from female and male gonadal transcriptomes onto the genome assembly resulted in the identification of 39,940 gene loci, 15.8% and 37.6% of which showed female-biased and male-biased expression, respectively. The genes that were over-expressed in females were mostly associated with molecular transportation, developmental process, oocyte growth and reproductive process; whereas, the male-biased genes were enriched in rhythmic process, molecular transducer activity and synapse. Several genes involved in the juvenile hormone synthesis pathway were also identified. Conclusions The evolution of large insect genomes such as L. migratoria and C. hookeri genomes is most likely due to the accumulation of repetitive regions and intron elongation. MITEs contributed significantly to the growth of C. hookeri genome size yet are surprisingly absent from the T. cristinae genome. Sex-biased genes identified from gonadal tissues, including genes involved in juvenile hormone synthesis, provide interesting candidates for the further study of flexible reproduction in stick insects.
