scholarly journals Complex evolutionary history of the Y chromosome in flies of the Drosophila obscura species group

2019 ◽  
Author(s):  
Ryan Bracewell ◽  
Doris Bachtrog
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
Evolutionary History ◽  
Sex Chromosome ◽  
Species Group ◽  
Genomic Environment ◽  
History Of ◽  
Chromosome Formation ◽  
Dramatic Variation ◽  
Complex Evolutionary History

The Drosophila obscura species group shows dramatic variation in karyotype, including transitions among sex chromosomes. Members of the affinis and pseudoobscura subgroups contain a neo-X chromosome (a fusion of the X with an autosome), and it was shown that ancestral Y genes of Drosophila have become autosomal in species that contain the neo-X. Detailed analysis in species of the pseudoobscura subgroup revealed a translocation of ancestral Y genes to the small dot chromosome of that group. Here, we show that the Y-dot translocation is restricted to the pseudoobscura subgroup, and translocation of Y genes in the affinis subgroup followed a different route. We find that most ancestral Y genes moved independently to autosomal or X-linked locations in different taxa of the affinis subgroup, and we propose a dynamic model of sex chromosome formation and turnover in the obscura species group. Our results show that Y genes can find unique paths to escape an unfavorable genomic environment.

scholarly journals Complex Evolutionary History of the Y Chromosome in Flies of the Drosophila obscura Species Group

2020 ◽  
Vol 12 (5) ◽  
pp. 494-505
Author(s):  
Ryan Bracewell ◽  
Doris Bachtrog
Keyword(s):  
Detailed Analysis ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Evolutionary History ◽  
Sex Chromosome ◽  
Species Group ◽  
History Of ◽  
Chromosome Formation ◽  
Dramatic Variation ◽  
Complex Evolutionary History

Abstract The Drosophila obscura species group shows dramatic variation in karyotype, including transitions among sex chromosomes. Members of the affinis and pseudoobscura subgroups contain a neo-X chromosome (a fusion of the X with an autosome), and ancestral Y genes have become autosomal in species harboring the neo-X. Detailed analysis of species in the pseudoobscura subgroup revealed that ancestral Y genes became autosomal through a translocation to the small dot chromosome. Here, we show that the Y-dot translocation is restricted to the pseudoobscura subgroup, and translocation of ancestral Y genes in the affinis subgroup likely followed a different route. We find that most ancestral Y genes have translocated to unique autosomal or X-linked locations in different taxa of the affinis subgroup, and we propose a dynamic model of sex chromosome formation and turnover in the obscura species group. Our results suggest that Y genes can find unique paths to escape unfavorable genomic environments that form after sex chromosome–autosome fusions.

scholarly journals Bisection of the X chromosome disrupts the initiation of chromosome silencing during meiosis in Caenorhabditis elegans

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yisrael Rappaport ◽  
Hanna Achache ◽  
Roni Falk ◽  
Omer Murik ◽  
Oren Ram ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Rna Polymerase Ii ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Transcription Analysis ◽  
X Chromosomes ◽  
Unique Character ◽  
Active Transcription ◽  
Heterogametic Sex

AbstractDuring meiosis, gene expression is silenced in aberrantly unsynapsed chromatin and in heterogametic sex chromosomes. Initiation of sex chromosome silencing is disrupted in meiocytes with sex chromosome-autosome translocations. To determine whether this is due to aberrant synapsis or loss of continuity of sex chromosomes, we engineered Caenorhabditis elegans nematodes with non-translocated, bisected X chromosomes. In early meiocytes of mutant males and hermaphrodites, X segments are enriched with euchromatin assembly markers and active RNA polymerase II staining, indicating active transcription. Analysis of RNA-seq data showed that genes from the X chromosome are upregulated in gonads of mutant worms. Contrary to previous models, which predicted that any unsynapsed chromatin is silenced during meiosis, our data indicate that unsynapsed X segments are transcribed. Therefore, our results suggest that sex chromosome chromatin has a unique character that facilitates its meiotic expression when its continuity is lost, regardless of whether or not it is synapsed.

scholarly journals Deficit of Mitonuclear Genes on the Human X Chromosome Predates Sex Chromosome Formation

2015 ◽  
Vol 7 (2) ◽  
pp. 636-641 ◽  
Author(s):  
Rebecca Dean ◽  
Fabian Zimmer ◽  
Judith E. Mank
Keyword(s):  
X Chromosome ◽  
Sex Chromosome ◽  
Chromosome Formation

scholarly journals Genetic Diversity of Rice stripe necrosis virus and New Insights into Evolution of the Genus Benyvirus

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 737
Author(s):  
Issiaka Bagayoko ◽  
Marcos Giovanni Celli ◽  
Gustavo Romay ◽  
Nils Poulicard ◽  
Agnès Pinel-Galzi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Sierra Leone ◽  
Evolutionary History ◽  
Molecular Diversity ◽  
Genomic Data ◽  
Gene Recombination ◽  
Necrosis Virus ◽  
History Of ◽  
Complex Evolutionary History

The rice stripe necrosis virus (RSNV) has been reported to infect rice in several countries in Africa and South America, but limited genomic data are currently publicly available. Here, eleven RSNV genomes were entirely sequenced, including the first corpus of RSNV genomes of African isolates. The genetic variability was differently distributed along the two genomic segments. The segment RNA1, within which clusters of polymorphisms were identified, showed a higher nucleotidic variability than did the beet necrotic yellow vein virus (BNYVV) RNA1 segment. The diversity patterns of both viruses were similar in the RNA2 segment, except for an in-frame insertion of 243 nucleotides located in the RSNV tgbp1 gene. Recombination events were detected into RNA1 and RNA2 segments, in particular in the two most divergent RSNV isolates from Colombia and Sierra Leone. In contrast to BNYVV, the RSNV molecular diversity had a geographical structure with two main RSNV lineages distributed in America and in Africa. Our data on the genetic diversity of RSNV revealed unexpected differences with BNYVV suggesting a complex evolutionary history of the genus Benyvirus.

Rhizobial plasmids — replication, structure and biological role

2012 ◽  
Vol 7 (4) ◽  
pp. 571-586 ◽  
Author(s):  
Andrzej Mazur ◽  
Piotr Koper
Keyword(s):  
Genome Organization ◽  
Soil Bacteria ◽  
Evolutionary History ◽  
Bacterial Genome ◽  
Biological Role ◽  
Genome Architecture ◽  
Genomic Knowledge ◽  
History Of ◽  
Cryptic Plasmids ◽  
Complex Evolutionary History

AbstractSoil bacteria, collectively named rhizobia, can establish mutualistic relationships with legume plants. Rhizobia often have multipartite genome architecture with a chromosome and several extrachromosomal replicons making these bacteria a perfect candidate for plasmid biology studies. Rhizobial plasmids are maintained in the cells using a tightly controlled and uniquely organized replication system. Completion of several rhizobial genome-sequencing projects has changed the view that their genomes are simply composed of the chromosome and cryptic plasmids. The genetic content of plasmids and the presence of some important (or even essential) genes contribute to the capability of environmental adaptation and competitiveness with other bacteria. On the other hand, their mosaic structure results in the plasticity of the genome and demonstrates a complex evolutionary history of plasmids. In this review, a genomic perspective was employed for discussion of several aspects regarding rhizobial plasmids comprising structure, replication, genetic content, and biological role. A special emphasis was placed on current post-genomic knowledge concerning plasmids, which has enriched the view of the entire bacterial genome organization by the discovery of plasmids with a potential chromosome-like role.

scholarly journals A Gradual Process of Recombination Restriction in the Evolutionary History of the Sex Chromosomes in Dioecious Plants

PLoS Biology ◽  
2004 ◽  
Vol 3 (1) ◽  
pp. e4 ◽  
Author(s):  
Michael Nicolas ◽  
Gabriel Marais ◽  
Vladka Hykelova ◽  
Bohuslav Janousek ◽  
Valérie Laporte ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary History ◽  
Dioecious Plants ◽  
Gradual Process ◽  
History Of

scholarly journals The early evolutionary history of neo-sex chromosomes in Neotropical grasshoppers, Boliviacris noroestensis (Orthoptera: Acrididae: Melanoplinae)

2014 ◽  
Vol 111 (3) ◽  
pp. 321-327 ◽  
Author(s):  
Elio R.D. CASTILLO ◽  
Alberto TAFFAREL ◽  
Dardo A. MARTI
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary History ◽  
History Of

scholarly journals Organellar phylogenomics inform systematics in the green algal family Hydrodictyaceae (Chlorophyceae) and provide clues to the complex evolutionary history of plastid genomes in the green algal tree of life

2018 ◽  
Vol 105 (3) ◽  
pp. 315-329 ◽  
Author(s):  
Hilary A. McManus ◽  
Karolina Fučíková ◽  
Paul O. Lewis ◽  
Louise A. Lewis ◽  
Kenneth G. Karol
Keyword(s):  
Evolutionary History ◽  
Tree Of Life ◽  
Green Algal ◽  
Plastid Genomes ◽  
History Of ◽  
Complex Evolutionary History

A total evidence approach using palynological characters to infer the complex evolutionary history of the Asian Impatiens (Balsaminaceae)

Taxon ◽  
2012 ◽  
Vol 61 (2) ◽  
pp. 355-367 ◽  
Author(s):  
Steven B. Janssens ◽  
Yi Song Wilson ◽  
Yong-Ming Yuan ◽  
Anne Nagels ◽  
Erik F. Smets ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Total Evidence ◽  
History Of ◽  
Complex Evolutionary History

scholarly journals ANALYSIS OFALEXANDRIUM TAMARENSE(DINOPHYCEAE) GENES REVEALS THE COMPLEX EVOLUTIONARY HISTORY OF A MICROBIAL EUKARYOTE1

2012 ◽  
Vol 48 (5) ◽  
pp. 1130-1142 ◽  
Author(s):  
Cheong Xin Chan ◽  
Marcelo B. Soares ◽  
Maria F. Bonaldo ◽  
Jennifer H. Wisecaver ◽  
Jeremiah D. Hackett ◽  
...  
Keyword(s):  
Evolutionary History ◽  
History Of ◽  
Complex Evolutionary History
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