scholarly journals Genetic recombination variation in wild Robertsonian mice: on the role of chromosomal fusions and Prdm9 allelic background

2014 ◽  
Vol 281 (1786) ◽  
pp. 20140297 ◽  
Author(s):  
Laia Capilla ◽  
Nuria Medarde ◽  
Alexandra Alemany-Schmidt ◽  
Maria Oliver-Bonet ◽  
Jacint Ventura ◽  
...  
Keyword(s):  
House Mouse ◽  
Genetic Recombination ◽  
Chromosomal Rearrangements ◽  
Evolutionary Process ◽  
Genome Shuffling ◽  
Mus Musculus Domesticus ◽  
Recombination Rates ◽  
Chromosomal Distribution ◽  
Epigenetic Signatures

Despite the existence of formal models to explain how chromosomal rearrangements can be fixed in a population in the presence of gene flow, few empirical data are available regarding the mechanisms by which genome shuffling contributes to speciation, especially in mammals. In order to shed light on this intriguing evolutionary process, here we present a detailed empirical study that shows how Robertsonian (Rb) fusions alter the chromosomal distribution of recombination events during the formation of the germline in a Rb system of the western house mouse ( Mus musculus domesticus ). Our results indicate that both the total number of meiotic crossovers and the chromosomal distribution of recombination events are reduced in mice with Rb fusions and that this can be related to alterations in epigenetic signatures for heterochromatinization. Furthermore, we detected novel house mouse Prdm9 allelic variants in the Rb system. Remarkably, mean recombination rates were positively correlated with a decrease in the number of ZnF domains in the Prdm9 gene. The suggestion that recombination can be modulated by both chromosomal reorganizations and genetic determinants that control the formation of double-stranded breaks during meiosis opens new avenues for understanding the role of recombination in chromosomal speciation.

scholarly journals Biochemical and genetic analysis of the role of the viral polymerase in enterovirus recombination

2016 ◽  
Vol 44 (14) ◽  
pp. 6883-6895 ◽  
Author(s):  
Andrew Woodman ◽  
Jamie J. Arnold ◽  
Craig E. Cameron ◽  
David J. Evans
Keyword(s):  
Genetic Recombination ◽  
Evolutionary Process ◽  
Virus Genome ◽  
Biochemical Assay ◽  
Strand Transfer ◽  
Turnover Rates ◽  
Coding Region ◽  
Cis Acting ◽  
Polymerase Fidelity

Abstract Genetic recombination in single-strand, positive-sense RNA viruses is a poorly understand mechanism responsible for generating extensive genetic change and novel phenotypes. By moving a critical cis-acting replication element (CRE) from the polyprotein coding region to the 3′ non-coding region we have further developed a cell-based assay (the 3′CRE-REP assay) to yield recombinants throughout the non-structural coding region of poliovirus from dually transfected cells. We have additionally developed a defined biochemical assay in which the only protein present is the poliovirus RNA dependent RNA polymerase (RdRp), which recapitulates the strand transfer events of the recombination process. We have used both assays to investigate the role of the polymerase fidelity and nucleotide turnover rates in recombination. Our results, of both poliovirus intertypic and intratypic recombination in the CRE-REP assay and using a range of polymerase variants in the biochemical assay, demonstrate that RdRp fidelity is a fundamental determinant of recombination frequency. High fidelity polymerases exhibit reduced recombination and low fidelity polymerases exhibit increased recombination in both assays. These studies provide the basis for the analysis of poliovirus recombination throughout the non-structural region of the virus genome and provide a defined biochemical assay to further dissect this important evolutionary process.

scholarly journals Genic differentiation and origin of Robertsonian populations of the house mouse (Mus musculus domesticus Rutty)

1989 ◽  
Vol 53 (1) ◽  
pp. 29-44 ◽  
Author(s):  
Janice Britton-Davidian ◽  
Joseph H. Nadeau ◽  
Henri Croset ◽  
Louis Thaler
Keyword(s):  
Gene Flow ◽  
House Mouse ◽  
Mus Musculus ◽  
Western Europe ◽  
Chromosomal Rearrangements ◽  
Nuclear Gene ◽  
Electrophoretic Analysis ◽  
Mus Musculus Domesticus ◽  
Effective Population ◽  
Chromosomal Races

SummaryThis paper examines the relation between chromosomal and nuclear-gene divergence in 28 wild populations of the house mouse semi-species, Mus musculus domesticus, in Western Europe and North Africa. Besides describing the karyotypes of 15 of these populations and comparing them to those of 13 populations for which such information was already known, it reports the results of an electrophoretic survey of proteins encoded by 34 nuclear loci in all 28 populations. Karyotypic variation in this taxon involves only centric (or Robertsonian) fusions which often differ in arm combination and number between chromosomal races. The electrophoretic analysis showed that the amount of genic variation within Robertsonian (Rb) populations was similar to that for all-acrocentric populations, i.e. bearing the standard karyotype. Moreover, divergence between the two types of populations was extremely low. These results imply that centric fusions in mice have not modified either the level or the nature of genic variability. The genetic similarity between Rb and all-acrocentric populations is not attributed to the persistence of gene flow, since multiple fusions cause marked reproductive isolation. Rather, we attribute this extreme similarity to the very recent origin of chromosomal races in Europe. Furthermore, genic diversity measures suggest that geographically separated Rb populations have in situ and independent origins. Thus, Rb translocations are probably not unique events, but originated repeatedly. Two models are presented to explain how the rapid fixation of a series of chromosomal rearrangements can occur in a population without lowering variability in the nuclear genes. The first model assumes that chromosomal mutation rates are between 10−3 and 10−4 and that populations underwent a series of transient bottlenecks in which the effective population size did not fall below 35. In the second model, genic variability is restored following severe bottlenecks, through gene flow and recombination.

Meiotic recombination hotspots in plants

2006 ◽  
Vol 34 (4) ◽  
pp. 531-534 ◽  
Author(s):  
C. Mézard
Keyword(s):  
Plant Species ◽  
Meiotic Recombination ◽  
Large Scale ◽  
Genetic Recombination ◽  
Dna Fragments ◽  
Recombination Rates ◽  
Coding Regions ◽  
Recombination Hotspots ◽  
Meiotic Recombination Hotspots

Many studies have demonstrated that the distribution of meiotic crossover events along chromosomes is non-random in plants and other species with sexual reproduction. Large differences in recombination frequencies appear at several scales. On a large scale, regions of high and low rates of crossover have been found to alternate along the chromosomes in all plant species studied. High crossover rates have been reported to be correlated with several chromosome features (e.g. gene density and distance to the centromeres). However, most of these correlations cannot be extended to all plant species. Only a few plant species have been studied on a finer scale. Hotspots of meiotic recombination (i.e. DNA fragments of a few kilobases in length with a higher rate of recombination than the surrounding DNA) have been identified in maize and rice. Most of these hotspots are intragenic. In Arabidopsis thaliana, we have identified several DNA fragments (less than 5 kb in size) with genetic recombination rates at least 5 times higher than the whole-chromosome average [4.6 cM (centimorgan)/Mb], which are therefore probable hotspots for meiotic recombination. Most crossover breakpoints lie in intergenic or non-coding regions. Major efforts should be devoted to characterizing meiotic recombination at the molecular level, which should help to clarify the role of this process in genome evolution.

scholarly journals Weak Correlation between Nucleotide Variation and Recombination Rate across the House Mouse Genome

2020 ◽  
Vol 12 (4) ◽  
pp. 293-299
Author(s):  
Michael E Kartje ◽  
Peicheng Jing ◽  
Bret A Payseur
Keyword(s):  
House Mouse ◽  
Recombination Rate ◽  
Mouse Genome ◽  
Purifying Selection ◽  
Nucleotide Variation ◽  
Mus Musculus Domesticus ◽  
Recombination Rates ◽  
Cpg Dinucleotides ◽  
Western European ◽  
Genomic Regions

Abstract Positive selection and purifying selection reduce levels of variation at linked neutral loci. One consequence of these processes is that the amount of neutral diversity and the meiotic recombination rate are predicted to be positively correlated across the genome—a prediction met in some species but not others. To better document the prevalence of selection at linked sites, we used new and published whole-genome sequences to survey nucleotide variation in population samples of the western European house mouse (Mus musculus domesticus) from Germany, France, and Gough Island, a remote volcanic island in the south Atlantic. Correlations between sequence variation and recombination rates estimated independently from dense linkage maps were consistently very weak (ρ ≤ 0.06), though they exceeded conventional significance thresholds. This pattern persisted in comparisons between genomic regions with the highest and lowest recombination rates, as well as in models incorporating the density of transcribed sites, the density of CpG dinucleotides, and divergence between mouse and rat as covariates. We conclude that natural selection affects linked neutral variation in a restricted manner in the western European house mouse.

Genetic differentiation within and away from the chromosomal rearrangements characterising hybridising chromosomal races of the western house mouse (Mus musculus domesticus)

2016 ◽  
Vol 24 (2) ◽  
pp. 271-280 ◽  
Author(s):  
Daniel W. Förster ◽  
Eleanor P. Jones ◽  
Fríða Jóhannesdóttir ◽  
Sofia I. Gabriel ◽  
Mabel D. Giménez ◽  
...  
Keyword(s):  
Genetic Differentiation ◽  
House Mouse ◽  
Mus Musculus ◽  
Chromosomal Rearrangements ◽  
Mus Musculus Domesticus ◽  
Chromosomal Races

scholarly journals Same Invasion, Different Routes: Helminth Assemblages May Favor the Invasion Success of the House Mouse in Senegal

2021 ◽  
Vol 8 ◽  
Author(s):  
Christophe Diagne ◽  
Laurent Granjon ◽  
Caroline Tatard ◽  
Alexis Ribas ◽  
Arame Ndiaye ◽  
...  
Keyword(s):  
House Mouse ◽  
Native Species ◽  
Invasion Success ◽  
Enemy Release ◽  
Mus Musculus Domesticus ◽  
Invasion Pathways ◽  
Invasion Fronts ◽  
Invasion Routes ◽  
Rodent Communities

Previous field-based studies have evidenced patterns in gastrointestinal helminth (GIH) assemblages of rodent communities that are consistent with “enemy release” and “spill-back” hypotheses, suggesting a role of parasites in the ongoing invasion success of the exotic house mouse (Mus musculus domesticus) in Senegal (West Africa). However, these findings came from a single invasion route, thus preventing to ascertain that they did not result from stochastic and/or selective processes that could differ across invasion pathways. In the present study, we investigated the distribution of rodent communities and their GIH assemblages in three distinct zones of Northern Senegal, which corresponded to independent house mouse invasion fronts. Our findings first showed an unexpectedly rapid spread of the house mouse, which reached even remote areas where native species would have been expected to dominate the rodent communities. They also strengthened previous insights suggesting a role of helminths in the invasion success of the house mouse, such as: (i) low infestation rates of invading mice by the exotic nematode Aspiculuris tetraptera at invasion fronts—except in a single zone where the establishment of the house mouse could be older than initially thought, which was consistent with the “enemy release” hypothesis; and (ii) higher infection rates by the local cestode Mathevotaenia symmetrica in native rodents with long co-existence history with invasive mice, bringing support to the “spill-back” hypothesis. Therefore, “enemy release” and “spill-back” mechanisms should be seriously considered when explaining the invasion success of the house mouse—provided further experimental works demonstrate that involved GIHs affect rodent fitness or exert selective pressures. Next steps should also include evolutionary, immunological, and behavioral perspectives to fully capture the complexity, causes and consequences of GIH variations along these invasion routes.

Electron Microscopy and image analysis of nucleo-protein complexes

1994 ◽  
Vol 52 ◽  
pp. 88-89
Author(s):  
E. H. Egelman ◽  
X. Yu
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Normal Cell ◽  
Genetic Recombination ◽  
Protein Complexes ◽  
Chromosomal Rearrangements ◽  
Reca Protein ◽  
E Coli ◽  
Helical Polymer ◽  
Specific Protease

The RecA protein of E. coli has been shown to mediate genetic recombination, regulate its own synthesis, control the expression of other genes, act as a specific protease, form a helical polymer and have an ATPase activity, among other observed properties. The unusual filament formed by the RecA protein on DNA has not previously been shown to exist outside of bacteria. Within this filament, the 36 Å pitch of B-form DNA is extended to about 95 Å, the pitch of the RecA helix. We have now establishedthat similar nucleo-protein complexes are formed by bacteriophage and yeast proteins, and availableevidence suggests that this structure is universal across all of biology, including humans. Thus, understanding the function of the RecA protein will reveal basic mechanisms, in existence inall organisms, that are at the foundation of general genetic recombination and repair.Recombination at this moment is assuming an importance far greater than just pure biology. The association between chromosomal rearrangements and neoplasms has become stronger and stronger, and these rearrangements are most likely products of the recombinatory apparatus of the normal cell. Further, damage to DNA appears to be a major cause of cancer.

On the role of conflict in the evolutionary process

2016 ◽  
pp. 87-91
Author(s):  
V.I. Bol’shakov ◽  
◽  
Yu.I. Dubrov ◽  
Keyword(s):  
Evolutionary Process
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