Songbird germline-restricted chromosome as a potential arena of genetic conflicts.

Genetic conflicts can arise between components of the genome with different inheritance strategies. The germline-restricted chromosome (GRC) of songbirds shows unusual mitotic and meiotic transmission compared with the rest of the genome. It is excluded from somatic cells and maintained only in the germline.

Rapid gene content turnover on the germline-restricted chromosome in songbirds.

The germline-restricted chromosome (GRC) of songbirds represents a taxonomically widespread example of programmed DNA elimination. Despite its apparent indispensability, we still know very little about the GRC's genetic composition, function, and evolutionary significance. Here we assemble the GRC in two closely related species, the common and thrush nightingale.

Micro Germline-Restricted Chromosome in Blue Tits: Evidence for Meiotic Functions.

The germline-restricted chromosome (GRC) is likely present in all songbird species but differs widely in size and gene content. This extra chromosome has been described as either a microchromosome with only limited basic gene content or a macrochromosome with enriched gene functions related to female gonad and embryo development. Here, we assembled, annotated, and characterized the first micro-GRC in the blue tit (Cyanistes caeruleus) using high-fidelity long-read sequencing data.

In-Depth Satellitome Analyses of 37 Drosophila Species Illuminate Repetitive DNA Evolution in the Drosophila Genus.

Satellite DNAs (SatDNA) are ubiquitously present in eukaryotic genomes and have been recently associated with several biological roles. Understanding the evolution and significance of SatDNA requires an extensive comparison across multiple phylogenetic depths. We combined the RepeatExplorer pipeline and cytogenetic approaches to conduct a comprehensive identification and analysis of the satellitome in 37 species from the genus Drosophila.

Mendelian nightmares: the germline-restricted chromosome of songbirds.

Germline-restricted chromosomes (GRCs) are accessory chromosomes that occur only in germ cells. They are eliminated from somatic cells through programmed DNA elimination during embryo development. GRCs have been observed in several unrelated animal taxa and show peculiar modes of non-Mendelian inheritance and within-individual elimination.

Satellitome comparison of two oedipodine grasshoppers highlights the contingent nature of satellite DNA evolution.

Background: The full catalog of satellite DNA (satDNA) within a same genome constitutes the satellitome. The Library Hypothesis predicts that satDNA in relative species reflects that in their common ancestor, but the evolutionary mechanisms and pathways of satDNA evolution have never been analyzed for full satellitomes. We compare here the satellitomes of two Oedipodine grasshoppers (Locusta migratoria and Oedaleus decorus) which shared their most recent common ancestor about 22.

Occasional paternal inheritance of the germline-restricted chromosome in songbirds.

Songbirds have one special accessory chromosome, the so-called germline-restricted chromosome (GRC), which is only present in germline cells and absent from all somatic tissues. Earlier work on the zebra finch () showed that the GRC is inherited only through the female line-like the mitochondria-and is eliminated from the sperm during spermatogenesis. Here, we show that the GRC has the potential to be paternally inherited.

Transposable element landscapes illuminate past evolutionary events in the endangered fern .

is an endangered tetraploid fern species with a large genome (10.5 Gb). Its geographical distribution is characterized by disjoined tertiary flora refuges, with relict populations that survived past climate crises.

Out of patterns, the euchromatic B chromosome of the grasshopper Abracris flavolineata is not enriched in high-copy repeats.

In addition to the normal set of standard (A) chromosomes, some eukaryote species harbor supernumerary (B) chromosomes. In most cases, B chromosomes show differential condensation with respect to A chromosomes and display dark C-bands of heterochromatin, and some of them are highly enriched in repetitive DNA. Here we perform a comprehensive NGS (next-generation sequencing) analysis of the repeatome in the grasshopper Abracris flavolineata aimed at uncovering the molecular composition and origin of its B chromosome.

A Long-Term Conserved Satellite DNA That Remains Unexpanded in Several Genomes of Characiformes Fish Is Actively Transcribed.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satellite DNAs (satDNAs). These sequences are highly dynamic and tend to be genus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, ∼140-78 Ma, whereas its nucleotide composition has remained considerably conserved in several taxa.

Development and characterization of 15 novel polymorphic microsatellite loci for two important bot flies (Diptera, Oestridae) by next-generation sequencing.

Cephenemyia stimulator and Oestrus ovis are two important parasitic bot flies (Oestridae) species causing myiasis, with a potential negative impact on the welfare of the host. Using next-generation sequencing approach and bioinformatics tools, a large panel of possible microsatellites loci was obtained in both species. Primer pairs were designed for 15 selected microsatellite loci in C.

Satellitome Analysis in the Ladybird Beetle (Coleoptera, Coccinellidae).

is one of the most commercialized ladybirds used for the biological control of aphid pest species in many economically important crops. This species is the first Coccinellidae whose satellitome has been studied by applying new sequencing technologies and bioinformatics tools. We found that 47% of the genome is composed of repeated sequences.

High dynamism for neo-sex chromosomes: satellite DNAs reveal complex evolution in a grasshopper.

A common characteristic of sex chromosomes is the accumulation of repetitive DNA, which accounts for their diversification and degeneration. In grasshoppers, the X0 sex-determining system in males is considered ancestral. However, in some species, derived variants like neo-XY in males evolved several times independently by Robertsonian translocation.

Eight Million Years of Satellite DNA Evolution in Grasshoppers of the Genus Schistocerca Illuminate the Ins and Outs of the Library Hypothesis.

Satellite DNA (satDNA) is an abundant class of tandemly repeated noncoding sequences, showing high rate of change in sequence, abundance, and physical location. However, the mechanisms promoting these changes are still controversial. The library model was put forward to explain the conservation of some satDNAs for long periods, predicting that related species share a common collection of satDNAs, which mostly experience quantitative changes.

The complete mitochondrial genome of Talpa aquitania (Talpidae; Insectivora), a mole species endemic to northern Spain and southern France.

The complete mitogenome sequence of Talpa aquitania, a recently described Talpa species, was assembled using whole-genome sequencing data. It varies in length from 16,776 to 16,846 bp, contains 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, one origin of L-strand replication, and a control region. In the control region, which varied from 1320 to 1390 bp, we identified the extended termination-associated sequence (ETAS-1 and ETAS-2) and the conserved sequence blocks (CSB-1, 2, 3, B, C, D, E, F).

Publisher Correction: High-throughput analysis unveils a highly shared satellite DNA library among three species of fish genus Astyanax.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Programmed DNA elimination of germline development genes in songbirds.

In some eukaryotes, germline and somatic genomes differ dramatically in their composition. Here we characterise a major germline-soma dissimilarity caused by a germline-restricted chromosome (GRC) in songbirds. We show that the zebra finch GRC contains >115 genes paralogous to single-copy genes on 18 autosomes and the Z chromosome, and is enriched in genes involved in female gonad development.

Differential Expression of Genes Related to Sexual Determination Can Modify the Reproductive Cycle of (Characiformes: Characidae) in B Chromosome Carrier Individuals.

The species complex is one of the most studied with respect to origin, distribution, and frequency of B chromosomes, and is considered a model organism for evolutionary studies. Research using population inferences about the occurrence and frequency of the B chromosome shows seasonal variation between sexes, which is associated with the presence of this supernumerary element. We hypothesized that the B chromosome could influence the sex ratio of these animals.

Satellite DNA content of B chromosomes in the characid fish Characidium gomesi supports their origin from sex chromosomes.

The origin of supernumerary (B) chromosomes is clearly conditioned by their ancestry from the standard (A) chromosomes. Sequence similarity between A and B chromosomes is thus crucial to determine B chromosome origin. For this purpose, we compare here the DNA sequences from A and B chromosomes in the characid fish Characidium gomesi using two main approaches.