Evidence of a Slower-Z effect in Schistosoma japonicum DOI
Andrea Mrnjavac, Beatriz Viçoso

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: July 4, 2024

Abstract Sex-linked and autosomal loci experience different selective pressures evolutionary dynamics. X (or Z) chromosomes are often hemizygous, as Y W) degenerate. Such hemizygous regions can be under greater efficacy of selection, recessive mutations immediately exposed to selection in the heterogametic sex (the so-called Faster-X or Faster-Z effect). However, young non-recombining regions, Y/W have many functional genes, X/Z-linked therefore diploid. The sheltering on X/Z by homolog is expected drive a Slower-X (Slower-Z) effect for diploid loci, i.e. reduction selection. While has been studied extensively, much less known empirically about dynamics Z chromosomes. Here, we took advantage published population genomic data female-heterogametic human parasite Schistosoma japonicum characterize gene content diversity levels chromosome. We used metrics acting genes test differences relative autosomes. found consistent patterns suggesting reduced Ne, purifying both regions. Moreover, relaxed was particularly pronounced female-biased Z, predicted Slower-Z theory.

Language: Английский

Cytogenetics of insects in the era of chromosome-level genome assemblies DOI Creative Commons
Vladimir A. Lukhtanov, Elena A. Pazhenkova

Vavilov Journal of Genetics and Breeding, Journal Year: 2025, Volume and Issue: 29(2), P. 230 - 237

Published: April 10, 2025

Over the past few years, a revolution has occurred in cytogenetics, driven by emergence and spread of methods for obtaining high-quality chromosome-level genome assemblies. In fact, this led to new tool studying chromosomes chromosomal rearrangements, is thousands times more powerful than light microscopy. This revolutionized cytogenetics many groups insects which previously karyotype information, if available at all, was limited chromosome number. Even impressive are achievements genomic approach general patterns organization evolution insects. Thus, it been shown that rapid transformations numbers, often found order Lepidoptera, most carried out parsimonious way, as result simple fusions fissions chromosomes. It established these not random occur independently different phylogenetic lineages due reuse same ancestral breakpoints. tendency correlated with presence so-called interstitial telomeres, i.e. telomere-like structures located ends chromosomes, but inside them. revealed that, insects, telomeric DNA just set short repeats, very long sequence consisting (TTAGG) n (or other motifs), regularly specifically interrupted retrotransposons, motifs diverse terms their length nucleotide composition. The number assemblies GenBank database growing exponentially now exceeds thousand species. Therefore, exceptional prospects using data analysis beyond doubt.

Language: Английский

Citations

0
Rewinding the ratchet: rare recombination locally rescues neo-W degeneration and generates plateaus of sex-chromosome divergence DOI Creative Commons
Thomas Decroly, Roger Vila, Konrad Lohse

et al.

Molecular Biology and Evolution, Journal Year: 2024, Volume and Issue: 41(7)

Published: July 1, 2024

Natural selection is less efficient in the absence of recombination. As a result, nonrecombining sequences, such as sex chromosomes, tend to degenerate over time. Although outcomes recombination arrest are typically observed after many millions generations, recent neo-sex chromosomes can give insight into early stages this process. Here, we investigate evolution Spanish marbled white butterfly, Melanargia ines, where Z-autosome fusion has turned homologous autosome neo-W chromosome. We show that these likely limited Iberian population M. and they arose around time when split from North-African populations, 1.5 million years ago. Recombination chromosome led an excess premature stop-codons frame-shift mutations, reduced gene expression compared neo-Z Surprisingly, identified two regions ∼1 Mb at one end both diverged degraded than rest chromosome, suggesting history rare but repeated genetic exchange between chromosomes. These plateaus divergence suggest degradation be locally reversed by

Language: Английский

Citations

1
Evidence of a Slower-Z effect in Schistosoma japonicum DOI
Andrea Mrnjavac, Beatriz Viçoso

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: July 4, 2024

Abstract Sex-linked and autosomal loci experience different selective pressures evolutionary dynamics. X (or Z) chromosomes are often hemizygous, as Y W) degenerate. Such hemizygous regions can be under greater efficacy of selection, recessive mutations immediately exposed to selection in the heterogametic sex (the so-called Faster-X or Faster-Z effect). However, young non-recombining regions, Y/W have many functional genes, X/Z-linked therefore diploid. The sheltering on X/Z by homolog is expected drive a Slower-X (Slower-Z) effect for diploid loci, i.e. reduction selection. While has been studied extensively, much less known empirically about dynamics Z chromosomes. Here, we took advantage published population genomic data female-heterogametic human parasite Schistosoma japonicum characterize gene content diversity levels chromosome. We used metrics acting genes test differences relative autosomes. found consistent patterns suggesting reduced Ne, purifying both regions. Moreover, relaxed was particularly pronounced female-biased Z, predicted Slower-Z theory.

Language: Английский

Citations

0