Recombination directionality factors (RDFs), or excisionases, are essential players of prophage excisive recombination. Despite the essentially catalytic role of the integrase in both integrative and excisive recombination, RDFs are required to direct the reaction towards excision and to prevent re-integration of the prophage genome when entering a lytic cycle. KplE1, HK620 and numerous (pro)phages that integrate at the same site in enterobacteria genomes (such as the argW tRNA gene) all share a highly conserved recombination module. This module comprises the attL and attR recombination sites and the RDF and integrase genes. The KplE1 RDF was named TorI after its initial identification as a negative regulator of the tor operon. However, it was characterized as an essential factor of excisive recombination. In this study, we designed an extensive random mutagenesis protocol of the torI gene and identified key residues involved in both functions of the TorI protein. We show that, in addition to TorI-TorR
Meiosis is a cell division process that produces haploid gametes from diploid cells. Several important meiotic events take place during prophase of meiosis I, most important being homologous chromosome pairing, meiotic recombination and formation of the synaptonemal complex (SC). These processes assure proper segregation of the homologous chromosomes into the haploid germ cells. Improper segregation of the homologos can cause chromosomal abnormality (aneuploidy), which causes various human disorders, notably mental retardation and pregnancy loss.. This thesis focuses on the relationship between recombination and the formation of SCs, aggregates of SC-related materials (polycomplexes) and recombination enzymes during meiosis. We have investigated SC formation in the absence of recombination, nature of polycomplexes and recombination enzymes in relation to the SCs structures and recombination nodules (RNs) in yeast Saccharomyces cerevisiae.. Studies on yeast mutants suggest that the formation of ...
To further establish the unusually high recombination rates of imprinted regions, it is informative to ask whether these have higher recombination rates than their flanking sequences. Of 16 bins containing an imprint, 3 have a sex-averaged recombination rate lower than the mean of the 3 flanking bins on either side, while 13 have a higher rate (P = 0.011, sign test; similar results are obtained for comparisons to the 5 or 10 flanking bins on either side). To examine the magnitude of this difference, we considered the difference in the recombination rate for every autosomal 1-Mb bin and the mean of the 3 flanking bins on either side. We then compared the data for imprinted bins with that of the genome as a whole. The sex-averaged recombination rate is higher than that predicted from the flanking blocks (Mann-Whitney U-test, P = 0.0074).. Thus, we report that for 13 of 16 imprinted regions the rate of recombination is higher in female meiosis compared to male meiosis, strongly suggesting that ...
60125DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 1rkycwgcttt yktrtacnaa stsgb 25225DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 2agccwgcttt yktrtacnaa ctsgb 25325DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 3gttcagcttt cktrtacnaa ctsgb 25425DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 4agccwgcttt cktrtacnaa gtsgb 25525DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 5gttcagcttt yktrtacnaa gtsgb 25625DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 6agcctgcttt tttgtacaaa cttgt 25725DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 7agcctgcttt cttgtacaaa cttgt 25825DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence 8acccagcttt cttgtacaaa gtggt 25925DNAUnknownDescription of Unknown Recombination products oligonucleotide sequence ...
In the nematode Caenorhabditis elegans, recombination suppression in translocation heterozygotes is severe and extensive. We have examined the meiotic properties of two translocations involving chromosome I, szT1(I;X) and hT1(I;V). No recombination was observed in either of these translocation heterozygotes along the left (let-362-unc-13) 17 map units of chromosome I. Using half-translocations as free duplications, we mapped the breakpoints of szT1 and hT1. The boundaries of crossover suppression coincided with the physical breakpoints. We propose that DNA sequences at the right end of chromosome I facilitate pairing and recombination. We use the data from translocations of other chromosomes to map the location of pairing sites on four other chromosomes. hT1 and szT1 differed markedly in their effect on recombination adjacent to the crossover suppressed region. hT1 had no effect on recombination in the adjacent interval. In contrast, the 0.8 map unit interval immediately adjacent to the ...
Author Summary Homologous recombination is an indispensable feature of the mammalian meiotic program and an important mechanism for creating genetic diversity. Despite its central significance, recombination rates vary markedly between species and among individuals. Although recent studies have begun to unravel the genetic basis of recombination rate variation within populations, the genetic mechanisms of species divergence in recombination rate remain poorly characterized. In this study, we show that two closely related house mouse subspecies differ in their genomic recombination rates by ∼30%, providing an excellent model system for studying evolutionary divergence in this trait. Using quantitative genetic methods, we identify eight genomic regions that contribute to divergence in global recombination rate between these subspecies, including large effect loci and multiple loci on the X-chromosome. Our study uncovers novel genomic loci contributing to species divergence in global recombination rate
In Saccharomyces cerevisiae, Rad59 is required for multiple homologous recombination mechanisms and viability in DNA replication-defective rad27 mutant cells. Recently, four rad59 missense alleles were found to have distinct effects on homologous recombination that are consistent with separation-of-function mutations. The rad59-K166A allele alters an amino acid in a conserved α-helical domain, and, like the rad59 null allele diminishes association of Rad52 with double-strand breaks. The rad59-K174A and rad59-F180A alleles alter amino acids in the same domain and have genetically similar effects on homologous recombination. The rad59-Y92A allele alters a conserved amino acid in a separate domain, has genetically distinct effects on homologous recombination, and does not diminish association of Rad52 with double-strand breaks. In this study, rad59 mutant strains were crossed with a rad27 null mutant to examine the effects of the rad59 alleles on the link between viability, growth and the stimulation of
View Notes - Bacterial Recombination from MCB 2000 at University of Florida. BACTERIAL RECOMBINATION Purposes A. Vaccine production (subunit type) B. Production of proteins (growth hormone) C.
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To create this landmark map, Comeron and colleagues generated recombinant advanced intercross lines (RAIL), derived from eight crosses among twelve wild-derived lines. To accurately identify crossover and noncrossover events, haplotype rather than genotype data are required, and Comeron and colleagues use a clever technique to recover haplotypes. RAIL females were individually crossed to D. simulans, and the genomes of single hybrid progeny were sequenced with Illumina technology. Reads mapping to D. simulans were removed bioinformatically to reveal a haploid, meiotically produced D. melanogaster genome. In all, over 100,000 recombination events were localized with kilobase-level precision.. Certainly, this genome-wide recombination map will empower population genetic and molecular evolutionary studies in Drosophila for years to come. However, the sheer number of events catalogued combined with the resolution at which breakpoints could be mapped facilitates a great deal more than quantifying ...
Recombination increases dramatically during meiosis to promote genetic exchange and generate recombinant progeny. Interestingly, meiotic recombination is unevenly distributed throughout genomes, and, as a consequence, genetic and physical map distances do not have a simple linear relationship. Recombination hotspots and coldspots have been described in many organisms and often reflect global features of chromosome structure. In particular, recombination frequencies are often distorted within or outside sex-determining regions of the genome. Here, we report that recombination is elevated adjacent to the mating-type locus (MAT) in the pathogenic basidiomycete Cryptococcus neoformans. Among fungi, C. neoformans has an unusually large MAT locus, and recombination is suppressed between the two |100-kilobase mating-type specific alleles. When genetic markers were introduced at defined physical distances from MAT, we found the meiotic recombination frequency to be ~20% between MAT and a flanking marker at 5,
Recombination hotspots are regions in a genome that exhibit elevated rates of recombination relative to a neutral expectation. The recombination rate within hotspots can be hundreds of times that of the surrounding region. Recombination hotspots result from higher DNA break formation in these regions, and apply to both mitotic and meiotic cells. This appellation can refer to recombination events resulting from the uneven distribution of programmed meiotic double-strand breaks. Meiotic recombination through crossing over is thought to be a mechanism by which a cell promotes correct segregation of homologous chromosomes and repair of DNA damages. Crossing over requires a DNA double-stranded break followed by strand invasion of the homolog and subsequent repair. Initiation sites for recombination are usually identified by mapping crossing over events through pedigree analysis or through analysis of linkage disequilibrium. Linkage disequilibrium has identified more than 30,000 hotspots within the ...
Crossover generated by meiotic recombination is a fundamental event that facilitates meiosis and sexual reproduction. Comparative studies have shown wide variation in recombination rate among species, but the characterization of recombination features between cattle breeds has not yet been performed. Cattle populations in North America count millions, and the dairy industry has genotyped millions of individuals with pedigree information that provide a unique opportunity to study breed-level variations in recombination. Based on large pedigrees of Jersey, Ayrshire and Brown Swiss cattle with genotype data, we identified over 3.4 million maternal and paternal crossover events from 161,309 three-generation families. We constructed six breed- and sex-specific genome-wide recombination maps using 58,982 autosomal SNPs for two sexes in the three dairy cattle breeds. A comparative analysis of the six recombination maps revealed similar global recombination patterns between cattle breeds but with significant
Accessory replicative helicases aid the primary replicative helicase in duplicating protein-bound DNA, especially transcribed DNA. Recombination enzymes also aid genome duplication by facilitating the repair of DNA lesions via strand exchange and also processing of blocked fork DNA to generate structures onto which the replisome can be reloaded. There is significant interplay between accessory helicases and recombination enzymes in both bacteria and lower eukaryotes but how these replication repair systems interact to ensure efficient genome duplication remains unclear. Here, we demonstrate that the DNA content defects of Escherichia coli cells lacking the strand exchange protein RecA are driven primarily by conflicts between replication and transcription, as is the case in cells lacking the accessory helicase Rep. However, in contrast to Rep, neither RecA nor RecBCD, the helicase/exonuclease that loads RecA onto dsDNA ends, is important for maintaining rapid chromosome duplication. Furthermore, RecA
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We have characterized homologous recombination between linear DNA and the bacterial chromosome that depends on λ recombination functions, involves very short homologies, and is very efficient. We examined several parameters to establish a maximal efficiency for phage-mediated recombination with short homologies. Maximal recombination levels are achieved with induction times from 7.5-17.5 min at 42°C, and a homology segment of 40-50 bp. Recombination saturates at a linear DNA substrate concentration of about 300 molecules per cell.. The fact that 30- to 50-bp homologies are able to recombine in vivo opens a vast array of new possibilities for generating recombinant DNA. Several steps normally involved in generating recombinant DNA molecules are eliminated. Restriction enzyme digests are not required to generate DNA fragments, and DNA ligase reactions are not required to join different DNA fragments at novel junctions. PCR amplification followed by electroporation of the linear DNA into cells is ...
October 3, 2004. October 3, 2004 - In a paper published today in the online edition of Nature Genetics, a deCODE-led team of scientists present the results of a large-scale population study linking recombination rate with maternal age and fertility. In the paper, entitled Recombination rate and reproductive success in humans, the deCODE team establish a novel and significant correlation between recombination - the shuffling of chromosomal material that takes place in the formation of eggs and sperm - and maternal age and fertility. Specifically, the average number of recombinations in eggs that go on to become successful live births tends to increase with the mothers age, and mothers with a higher recombination rate in general also tend to have more children than do those with a lower recombination rate. The authors conclude that the most likely explanation for this phenomenon is that recombination, which is one of the most important mechanisms for generating genetic diversity in ...
Rates of intragenic recombination are suppressed in the vicinity of Ds and Mu1 insertions (23, 34, 40). In addition, Ds insertions are thought to alter the distribution of recombination breakpoints in the otherwise uniformly recombinogenic bz1 locus to create allele-specific hot and cold spots (34). In contrast, a preliminary analysis did not provide any evidence that a Mu1 insertion in the a1 gene alters the distribution of recombination event (23).. In this previous study, the positions of 15 recombination events isolated from the a1-mum2/a1∷rdt heterozygote were physically mapped within the 1.2-kb interval of the a1 gene that is defined by the Mu1 and rdt transposon insertions. All but one of these recombination events resolved within a 377-bp recombination hot spot. Xu et al. (23) compared this distribution of recombination events to those isolated from a directly comparable heterozygote that does not contain the Mu1 insertion in the a1 gene (A1-LC/a1∷rdt). This comparison is appropriate ...
TY - JOUR. T1 - ζ-/-thalassemic mice are affected by two modifying loci and display unanticipated somatic recombination leading to inherited variation. AU - Leder, Aya. AU - McMenamin, Jennifer. AU - Fontaine, Karen. AU - Bishop, Alexander. AU - Leder, Philip. PY - 2005/3/1. Y1 - 2005/3/1. N2 - Thalassemia is a disease caused by a variety of mutations affecting both the adult and embryonic α- and β-globin loci. A mouse strain carrying an embryonic ζ-globin gene disrupted by the insertion of a PGK-Neo cassette displays an α-thalassemia-like syndrome. Embryonic survival of this ζ-null mouse is variable and strongly influenced by genetic background, the 129/SvEv mouse strain displaying a more severe phenotype than C57BL/6. We have identified two modifying loci on C57BL/6 chromosomes 2 and 5, which affect the penetrance of embryonic lethality in the 129/SvEv mouse. Through this work, we were able to observe an interesting effect on somatic recombination events in thalassemic embryos. We show ...
The rapid spread of antimicrobial resistance and vaccine escape in the opportunistic human pathogen Streptococcus pneumoniae can be largely attributed to competence-induced transformation. To better understand why competence-induced transformation is so effective, we studied the dynamics of this process at the single-cell level. We show that within isogenic populations, all cells become naturally competent and bind exogenous DNA. In addition, we find that transformation is highly efficient and that the chromosomal location of the integration site or whether the transformed gene is encoded on the leading or lagging strand has limited influence on recombination efficiency. Indeed, we have observed multiple recombination events in single recipients in real-time. However, because of saturation of the DNA uptake and integration machinery and because a single stranded donor DNA replaces the original allele, we find that transformation efficiency has an upper threshold of approximately 50% of the population.
Sex and recombination are ubiquitous across the vast majority of life on earth. In eukaryotes, recombination during meiosis yields new variation that selection acts upon and, thus, facilitates evolution. However, meiosis provides an arena for manipulation and exploitation by selfish genetic elements. Selfish elements can increase in abundance independently of their host organism and frequently at a cost to host fitness. Several types of selfish elements act during meiosis and therefore it is possible for recombination rates and mechanisms to evolve to counteract and ameliorate their negative effects. However, few studies have investigated the interaction between recombination and selfish genetic elements. I conducted three studies on the evolution of recombination mechanisms in light of the impact of selfish elements. I begin my thesis with an introduction on selfish elements, recombination, and their possible interactions in Chapter 1. In Chapter 2, I found evidence that the synaptonemal ...
In viruses, recombination may allow foreign genes to be acquired or may create a composite genome through recombination between different virus variants. The ability to identify a recombinant virus and the positions where recombination occurred is only as certain as the identification of the component parental viral genomes from which it was generated. Recombination detection thus shares many elements and is ultimately dependent on evolutionary reconstructions and, most importantly, on methods for the delineation of separate phylogenetic groups. The structure of the 5 untranslated region (5 UTR) of picornaviruses provides a further example of modular exchange through recombination during the evolution of separate genera within the picornavirus family. Members of the same picornavirus genus show conserved gene order and content, and over the much shorter evolutionary time scale in which species and serotypes developed, gene exchange is best documented as homologous recombination events. One of the
Andrés Frankow. Genetic Recombination in Bacteria Horizon of the b. Uploaded by. Crispr methods for bacterial genome engineering. Homologous recombination has been most studied and is best understood for Escherichia coli. 1. an overview of bacterial recombination).The three main mechanisms by which bacteria acquire new DNA are transformation, conjugation, and transduction. 1. Introduction Deoxyribonucleic acid (DNA) damage is a common occurrence in all cells. Genetic recombination - transfer of DNA from one organism (donor) to another recipient. Many are downloadable. Saurav Suman. Bacteria Using Homologous Recombination 1.16.2 Supplement 78 Current Protocols in Molecular Biology of steps is a recombineering reaction that replaces the sequence to be modified with an antibiotic-resistance cassette and a counter-selectable marker (e.g., sacB, which is toxic when cells are grown on medium containing sucrose; Gay et al., 1985). Saurav Suman. Evolution of sexual reproduction is one of the major ...
Mutation and recombination are central processes driving microbial evolution. A high mutation rate fuels adaptation but also generates deleterious mutations. Recombination between two different genomes may resolve this paradox, alleviating effects of clonal interference and purging deleterious mutations. Here we demonstrate that recombination significantly accelerates adaptation and evolution during acute virus infection. We identified a poliovirus recombination determinant within the virus polymerase, mutation of which reduces recombination rates without altering replication fidelity. By generating a panel of variants with distinct mutation rates and recombination ability, we demonstrate that recombination is essential to enrich the population in beneficial mutations and purge it from deleterious mutations. The concerted activities of mutation and recombination are key to virus spread and virulence in infected animals. These findings inform a mathematical model to demonstrate that poliovirus ...
Meiotic recombination hotspots control the frequency and distribution of Spo11 (Rec12)-initiated recombination in the genome. Recombination occurs within and is regulated in part by chromatin structure, but relatively few of the many chromatin remodeling factors and histone posttranslational modifications (PTMs) have been interrogated for a role in the process. We developed a chromatin affinity purification and mass spectrometry-based approach to identify proteins and histone PTMs that regulate recombination hotspots. Small (4.2 kbp) minichromosomes (MiniCs) bearing the fission yeast ade6-M26 hotspot or a basal recombination control were purified approximately 100,000-fold under native conditions from meiosis; then, associated proteins and histone PTMs were identified by mass spectrometry. Proteins and PTMs enriched at the hotspot included known regulators (Atf1, Pcr1, Mst2, Snf22, H3K14ac), validating the approach. The abundance of individual histones varied dynamically during meiotic progression in
Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring. Most recombination is naturally occurring. During meiosis in eukaryotes, genetic recombination involves the pairing of homologous chromosomes. This may be followed by information transfer between the chromosomes. The information transfer may occur without physical exchange (a section of genetic material is copied from one chromosome to another, without the donating chromosome being changed) (see SDSA pathway in Figure); or by the breaking and rejoining of DNA strands, which forms new molecules of DNA (see DHJ pathway in Figure). Recombination may also occur during mitosis in eukaryotes where it ordinarily involves the two sister chromosomes formed after chromosomal replication. In this case, new combinations of ...
A direct test was made of predictions of the double-strand-break repair (DSBR) model of recombination in Xenopus laevis oocytes. The DNA substrate injected into oocytes had two directly repeated copies of a 1.25-kb sequence and was cleaved within one of them. Different products were expected to result from concerted, conservative events, as predicted by the DSBR model, and from nonconservative events. Only very low levels of recombination products, both conservative and nonconservative, were observed. When individual, apparent DSBR products were cloned and characterized, it emerged that the majority of them had arisen by nonconservative recombination through short, terminal homologies and not from the gene conversion events predicted for DSBR. Two cloned products among 44 tested corresponded to the predications of the DSBR model, but these could also have been generated by other processes. The most efficient recombination events in oocytes are nonconservative and are based on long, terminal ...
In yeast meiosis, ascosporal colonies are sometimes sectored for a marker--i.e., half the colony has one allele and half has the other. This is interpreted as replicative resolution of heteroduplex DNA (hDNA) formed as a recombination intermediate. We have looked for similar evidence of hDNA formation during mitotic recombination between two repeated sequences on the same chromosome. The two repeats, an ochre suppressor and a wild-type tRNA gene, are separated by plasmid DNA and the URA3 marker. Recombination between the repeats excises the URA3 gene and one copy of the repeat, leaving either the wild-type tRNA or the suppressor on the chromosome. A red/white color assay is used to distinguish between the two. We find that some colonies that have lost the URA3 gene are sectored for the suppressor. This suggests that hDNA is formed across the anticodon during the recombination event and then resolved by replication. The disruption of either of two genes involved in recombination and repair, RAD1 and
[email protected] research • lab members • publications. My lab is active in three somewhat related research areas: 1) the mechanism of mitotic recombination, 2) the genetic regulation of genome stability, and 3) genetic instability associated with interstitial telomeric sequences. Almost all of our studies are done using the yeast Saccharomyces cerevisiae.. Mechanism of mitotic recombination. Mitotic recombination, an important mechanism for the repair of DNA damage, is less well characterized than meiotic recombination. One difficulty is that mitotic recombination events are 104-fold less frequent than meiotic recombination events. We developed a greatly improved system for identifying and mapping mitotic crossovers at 1-kb resolution throughout the genome. This system uses DNA microarrays to detect loss of heterozygosity (LOH) resulting from mitotic crossovers. We identified motifs associated with high levels of spontaneous mitotic recombination. In particular, we demonstrated that a ...
The emergence of novel pathogenic organisms due to the acquisition of virulence determinants from bacteriophages has generated significant interest in the pathways responsible for genomic rearrangements. Phageλ encodes its own recombination system, the Red system, comprising Exo, β and γ proteins. In addition,λ encodes another recombinase, Orf, which participates in the initial stages of genetic exchange and supplies a frmction equivalent to that of the Escherichia coli RecFOR proteins. This thesis focuses on determining the function of Orf in phage and bacterial recombination pathways by analysing its impact on recombinases encoded by λ and E. coli. Experiments revealed that Orf interacts with bacterial and phage recombination proteins in the initial exchange step of recombination, modulating the activities of both Exo and RecA. Orf, along with β, attenuates the 5-3 exonuclease activity of Exo, a feature that depends largely on the ability of Orf to bind DNA. Orf also facilitates ...
Parasites and hosts are involved in a continuous coevolutionary process leading to genetic changes in both counterparts. To understand this process, it is necessary to track host responses, one of which could be an increase in sex and recombination, such as is proposed by the Red Queen hypothesis. In this theoretical framework, the inducible recombination hypothesis states that B-chromosomes (genome parasites that prosper in natural populations of many living beings) elicit an increase in host chiasma frequency that is favoured by natural selection because it increases the proportion of recombinant progeny, some of which could be resistant to both B-chromosome effects and B-accumulation in the germline. We have found a clear parallelism between host recombination and the evolutionary status of the B-chromosome polymorphism, which provides explicit evidence for inducible recombination and strong support for the Red Queen hypothesis.. ...
Despite their importance to successful meiosis and various evolutionary processes, meiotic recombination rates sometimes vary within species or between closely related species. For example, humans and chimpanzees share virtually no recombination hotspot locations in the surveyed portion of the genom …
Although DNA is surprisingly fluid, there are enzymes that mediate recombination--by initiating DNA binding, strand invasion, and stabilizing ssDNA intermediates. Also, of important note, is that organisms have varying degrees of recombination levels. A classical example occurs within the Mycobacteria. Mycobacterium smegmatis has relatively low levels of illegitimate recombination (IR), while M. tuberculosis is notorious for high levels of IR compared to homologous recombination. This raises a question that can be phrased in a few ways. What enzymes are responsible for IR? or perhaps, What enzymes for homologous recombination are lacking ...
Lien vers Pubmed [PMID] - 15218022. J. Biol. Chem. 2004 Aug;279(35):36625-32. By frequently rearranging large regions of the genome, genetic recombination is a major determinant in the plasticity of the human immunodeficiency virus type I (HIV-1) population. In retroviruses, recombination mostly occurs by template switching during reverse transcription. The generation of retroviral vectors provides a means to study this process after a single cycle of infection of cells in culture. Using HIV-1-derived vectors, we present here the first characterization and estimate of the strength of a recombination hot spot in HIV-1 in vivo. In the hot spot region, located within the C2 portion of the gp120 envelope gene, the rate of recombination is up to ten times higher than in the surrounding regions. The hot region corresponds to a previously identified RNA hairpin structure. Although recombination breakpoints in vivo cluster in the top portion of the hairpin, the bias for template switching in this same ...
Meiotic recombination is initiated by DNA double-strand breaks (DSBs) created by the topoisomerase-like protein Spo11. During DSB formation, Spo11 becomes covalently attached to the 5 DSB ends. Removal of Spo11 is essential to repair the DSB by homologous recombination. Spo11 is removed endonucleolytically creating short-lived Spo11-oligonucleotide products. Here I demonstrate that: 1. Spo11-oligonucleotide products are not detected in recombination mutants believed to be defective in meiotic DSB formation. 2. When DSB repair is delayed, Spo11-oligonucleotides persist for longer. 3. Processing of Spo11-DSB ends to create Spo11-oligonucleotides is largely dependent on Mec1 and Tel1 activity. In the process of investigating Spo11-oligonucleotide degradation, it was observed that a mutant defective in both the meiotic recombination checkpoint and in DSB repair failed to accumulate the expected level of DSBs. Work described here leads to the proposal of a DSB feedback mechanism that functions ...
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The complex correlation structure of a collection of orthologous DNA sequences is uniquely captured by the ancestral recombination graph (ARG), a complete record of coalescence and recombination events in the history of the sample. However, existing methods for ARG inference are computationally in …
BACKGROUND:Genetic recombination can produce heterogeneous phylogenetic histories within a set of homologous genes. These recombination events can be obscured by subsequent residue substitutions, which consequently complicate their detection. While there are many algorithms for the identification of recombination events, little is known about the effects of subsequent substitutions on the accuracy of available recombination-detection approaches.RESULTS:We assessed the effect of subsequent substitutions on the detection of simulated recombination events within sets of four nucleotide sequences under a homogeneous evolutionary model. The amount of subsequent substitutions per site, prior evolutionary history of the sequences, and reciprocality or non-reciprocality of the recombination event all affected the accuracy of the recombination-detecting programs examined. Bayesian phylogenetic-based approaches showed high accuracy in detecting evidence of recombination event and in identifying ...
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The coordinated rearrangement of antigen receptor gene segments during V(D)J recombination is dependent on a complex series of DNA-processing reactions (20, 30, 45). Essential to the initiation of the process are recombination signal sequences (RSSs), which consist of two conserved DNA recognition motifs, the heptamer (consensus, CACAGTG) and the nonamer (consensus, ACAAAAACC) (32). These motifs are separated by predominantly nonconserved spacer regions of either 12 or 23 bp. Effective recombination is achieved by the 12/23 rule, which limits rearrangement to gene segments flanked by RSSs with different spacer lengths (15, 55, 60).. Recombination-activating genes 1 and 2 (RAG1 and RAG2) encode the lymphoid cell-specific recombinase components (36, 46) that are central to the rearrangement process. Normally, the V(D)J recombination reaction proceeds with nonamer recognition mediated by a DNA binding region of RAG1 (nonamer binding domain) that displays homology to the DNA recognition domains of ...
Recombination raises during meiosis to market genetic exchange and generate recombinant progeny dramatically. hereditary markers were released at described physical ranges from we discovered the meiotic recombination rate of recurrence to become ~20% between and a flanking marker at 5, 10, 50, or 100 kilobases from the proper border. As a total result, the physical/hereditary map percentage in the areas adjacent to can be distorted ~10- to 50-collapse set alongside the genome-wide normal. Moreover, recombination frequently occurred on both family member edges of and bad disturbance between crossovers was observed. heterozygosity had not been required for improved recombination, implying that process CALNA2 isnt because of a physical distortion from both non-paired alleles and may also happen during same-sex mating. Series analysis exposed a 68550-75-4 supplier relationship between high G + C content material and these hotspot areas. We hypothesize that the current presence of recombinational ...
I have posted a few times before about a new group bionet.molbio.recombination that I will be proposing soon.... Here is the rough proposal... if you have any comments please send them!!!! Start----------- Proposal to establish RECOMBINATION/bionet.molbio.recombination Proposed USENET name: bionet.molbio.recombination (unmoderated) Proposed mailing list name: RECOMBINATION Proposed e-mail addresses: recom at net.bio.net recom at daresbury.ac.uk Discussion leaders: Graham Dellaire, e-mail: popa0206 at po-box.mcgill.ca (b2xe at musicb.mcgill.ca) Department of Medicine (Div. of Exp. Medicine), McGill Univeristy, Montreal, Quebec, Canada George Szatmari, e-mail: szat at ere.umontreal.ca Tentatively Denis Cournoyer (Mcgill Experimental Medicine) (gene therapy) Terry Chow (McGill): e-mail MDTY at Musica.mcgill.ca (mammalian genetics) Charter: The purpose of the RECOMBINATION newsgroup is to provide a proper forum for the discussion of issues pertaining and involving recombination of DNA or RNA, in its ...
In the budding yeast Saccharomyces cerevisiae, unnatural stabilization of the cyclin-dependent kinase inhibitor Sic1 during meiosis can trigger extra rounds of DNA replication. When programmed DNA double-strand breaks are generated but not repaired due to absence of DMC1, a pathway involving the checkpoint gene RAD17 prevents this DNA rereplication. Further genetic analysis has now revealed that prevention of DNA rereplication also requires MEC1, which encodes a protein kinase that serves as a central checkpoint regulator in several pathways including the meiotic recombination checkpoint response. Downstream of MEC1, MEK1 is required through its function to inhibit repair between sister chromatids. By contrast, meiotic recombination checkpoint effectors that regulate gene expression and cyclin-dependent kinase activity are not necessary. Phosphorylation of histone H2A, which is catalyzed by Mec1 and the related Tel1 protein kinase in response to DNA double-strand breaks and can help coordinate ...
TY - JOUR. T1 - Predicting knot and catenane type of products of site-specific recombination on twist knot substrates. AU - Valencia, Karin. AU - Buck, Dorothy. N1 - Copyright © 2011 Elsevier Ltd. All rights reserved.. PY - 2011/8/12. Y1 - 2011/8/12. N2 - Site-specific recombination on supercoiled circular DNA molecules can yield a variety of knots and catenanes. Twist knots are some of the most common conformations of these products, and they can act as substrates for further rounds of site-specific recombination. They are also one of the simplest families of knots and catenanes. Yet, our systematic understanding of their implication in DNA and important cellular processes such as site-specific recombination is very limited. Here, we present a topological model of site-specific recombination characterizing all possible products of this reaction on twist knot substrates, extending the previous work of Buck and Flapan. We illustrate how to use our model to examine previously uncharacterized ...
Homologous recombination plays a central role in the repair of double-strand DNA breaks, the restart of stalled replication forks and the generation of genetic diversity. Regulation of recombination is essential since defects can lead to genome instability and chromosomal rearrangements. Strand exchange is a key step of recombination - it is catalysed by RecA in bacteria, Rad51/Dmc1 in eukaryotes and RadA in archaea. RadB, a paralogue of RadA, is present in many archaeal species. RadB has previously been proposed to function as a recombination mediator, assisting in RadA-mediated strand exchange. In this study, we use the archaeon Haloferax volcanii to provide evidence to support this hypothesis. We show that RadB is required for efficient recombination and survival following treatment with DNA-damaging agents, and we identify two point mutations in radA that suppress the ΔradB phenotype. Analysis of these point mutations leads us to propose that the role of RadB is to act as a recombination ...
Looking for online definition of nonreciprocal recombination in the Medical Dictionary? nonreciprocal recombination explanation free. What is nonreciprocal recombination? Meaning of nonreciprocal recombination medical term. What does nonreciprocal recombination mean?
Looking for negative interference? Find out information about negative interference. A crossover exchange between homologous chromosomes which increases the likelihood of another in the same vicinity Explanation of negative interference
Cre-Lox recombination is a special type of site-specific recombination. The Cre protein is a site-specific DNA recombinase. It can catalyze the recombination of DNA between specific sites in a DNA molecule. These sites, known as loxP sequences, contain specific binding sites for Cre that surround a directional core sequence where recombination can occur. It is often used in the generation of knockout and conditional knockout animals. - Cre-Lox Recombination - AbVideo™ - Support - Abnova
Neale, Matt (2010) PRDM9 points the zinc finger at meiotic recombination hotspots. Genome Biology, 11 (2). p. 104. ISSN 14656914 Full text not available from this repository ...
Genetic investigations of malaria require a genome-wide, high-resolution linkage map of Plasmodium falciparum. A genetic cross was used to construct such a map from 901 markers that fall into 14 inferred linkage groups corresponding to the 14 nuclear chromosomes. Meiotic crossover activity in the genome proved high (17 kilobases per centimorgan) and notably uniform over chromosome length. Gene conversion events and spontaneous microsatellite length changes were evident in the inheritance data. The markers, map, and recombination parameters are facilitating genome sequence assembly, localization of determinants for such traits as virulence and drug resistance, and genetic studies of parasite field populations. ...
Understanding the influences of population structure, selection, and recombination on polymorphism and linkage disequilibrium (LD) is integral to mapping genes contributing to drug resistance or virulence in Plasmodium falciparum. The parasites short generation time, coupled with a high cross-over rate, can cause rapid LD break-down. However, observations of low genetic variation have led to suggestions of effective clonality: selfing, population admixture, and selection may preserve LD in populations. Indeed, extensive LD surrounding drug-resistant genes has been observed, indicating that recombination and selection play important roles in shaping recent parasite genome evolution. These studies, however, provide only limited information about haplotype variation at local scales. Here we describe the first (to our knowledge) chromosome-wide SNP haplotype and population recombination maps for a global collection of malaria parasites, including the 3D7 isolate, whose genome has been sequenced previously.
We used circularization-dependent and orientation-specific split scAAV vectors as a model system for the characterization of recombination between different DNA HP structures. This virus-based delivery system permitted controlled and quantifiable transport of DNA substrates to the nucleus. By taking advantage of the unique properties of the scAAV genome, we could control the orientation of the reporter gene segments between the open and closed TR HP ends. This, in turn, allowed the measurement and characterization of recombination events between different kinds of HP structures, represented by AAV termini. We observed that both the open and closed HP scAAV ends can serve as substrates for circularization and concatemerization. The two TR HP ends are not equivalent in recombination efficiency or sensitivity to drug inhibition. Indeed, it was surprising to discover that the joining of two closed HP ends was more efficient than any combination involving an open TR in concatemerization. However, ...
TY - JOUR. T1 - The relation between recombination rate and patterns of molecular evolution and variation in Drosophila melanogaster. AU - Campos, José L. AU - Halligan, Daniel L. AU - Haddrill, Penelope R. AU - Charlesworth, Brian. PY - 2014/4. Y1 - 2014/4. N2 - Genetic recombination associated with sexual reproduction increases the efficiency of natural selection by reducing the strength of Hill-Robertson interference. Such interference can be caused either by selective sweeps of positively selected alleles or by background selection (BGS) against deleterious mutations. Its consequences can be studied by comparing patterns of molecular evolution and variation in genomic regions with different rates of crossing over. We carried out a comprehensive study of the benefits of recombination in Drosophila melanogaster, both by contrasting five independent genomic regions that lack crossing over with the rest of the genome and by comparing regions with different rates of crossing over, using data on ...
High resolution analyses indicate that meiotic crossovers in human autosomes tend to cluster into 1-2 kb hotspots separated by blocks of high LD tens to hundreds of kilobases long. In contrast, low resolution data suggest only modest regional variation in recombination efficiency across the 2.6 Mb Xp/Yp pseudoautosomal region (PAR1), a male-specific recombination hot domain with a recombination rate about twenty times higher than the genome average. Recent data suggest a more complex picture of PAR1 recombination. Around the SHOX gene, 500 kb from the telomere, LD decays extremely rapidly with physical distance, but nearly all crossovers cluster into a highly localised hotspot about 2 kb wide. In contrast, SNPs in a 1.5 kb region immediately adjacent to the PAR1 telomere are in intense LD, implying that this region is recombinationally inert and that male crossover activity terminates at a currently unidentified boundary in the distal region of PAR1. To further investigate PAR1 recombination, ...
Author(s): Yin, Yi; Petes, Thomas D | Abstract: In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs). Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH). In this study, LOH events induced by ultraviolet (UV) light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP) microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380
Triple-negative breast cancers (TNBC) lack expression of estrogen and progesterone receptors and overexpression or amplification of the HER2/neu oncogene, and are therefore not amenable to therapy directed at these targets. Sporadic (BRCA1 and BRCA2 germline wild-type) TNBCs share many characteristics with BRCA1 mutation-associated cancers, including a basal-like gene expression profile, frequent p53 mutations, and a high burden of genomic aberrations such as loss of heterozygosity (1-7). BRCA1 or BRCA2 (BRCA1/2)-mutated cancers have defects in several aspects of DNA repair including homologous recombination deficiency (HRD; refs. 1, 8). BRCA1/2 mutation-associated cancers have been shown to have increased sensitivity to DNA crosslinking agents such as platinum salts (9). A number of studies have suggested that some sporadic TNBC may bear substantial similarities to BRCA1/2-mutated cancers, including harboring DNA repair defects that might predispose to platinum sensitivity (1, 10, 11). ...
1. RaddingCM 1981 Recombination activities of E. coli recA protein. Cell 25 3 4. 2. LusettiSLCoxMM 2002 The bacterial RecA protein and the recombinational DNA repair of stalled replication forks. Annu Rev Biochem 71 71 100. 3. CoxMM 2007 Regulation of bacterial RecA protein function. Crit Rev Biochem Mol Biol 42 41 63. 4. CoxMM 2007 Motoring along with the bacterial RecA protein. Nat Rev Mol Cell Biol 8 127 138. 5. TamasIKlassonLCanbackBNaslundAKErikssonAS 2002 50 million years of genomic stasis in endosymbiotic bacteria. Science 296 2376 2379. 6. SeitzEMBrockmanJPSandlerSJClarkAJKowalczykowskiSC 1998 RadA protein is an archaeal RecA protein homolog that catalyzes DNA strand exchange. Genes Dev 12 1248 1253. 7. ShinoharaAOgawaHOgawaT 1992 Rad51 protein involved in repair and recombination in S. cerevisiae is a RecA-like protein. Cell 69 457 470. 8. VamvakasSVockEHLutzWK 1997 On the role of DNA double-strand breaks in toxicity and carcinogenesis. Crit Rev Toxicol 27 155 174. 9. KhannaKKJacksonSP ...
Malaria parasites undergo a mainly haploid life-cycle. The only diploid stage is the zygote, formed by fusion of gametes in the mosquito stomach. The first division of the zygote is a meiotic one, producing, after further mitotic divisions, haploid sporozoites. Genetic recombination occurs at meiosis, following cross-fertilization of gametes of parasites with different genotypes. This has been shown in laboratory studies by feeding mosquitoes on a mixture of Plasmodium falciparum clones and analyzing the resulting progeny for parasites with non-parental combinations of the clone markers. Such recombinants are produced at a higher than expected frequency. There is considerable genotype diversity in field populations of P. falciparum. Evidence that recombination in mosquitoes is the principal cause of this diversity is two-fold. First, parasites isolated from patients in small isolated communities at the same time are genetically very diverse. No two isolates examined for polymorphic markers at ...
The tumor suppressor p53 is a transcription factor whose function is critical for maintaining genomic stability in mammalian cells. In response to DNA damage, p53 initiates a signaling cascade that results in cell cycle arrest, DNA repair or, if the damage is severe, programmed cell death. In addition, p53 interacts with repair proteins involved in homologous recombination. Mitotic homologous recombination (HR) plays an essential role in the repair of double-strand breaks (DSBs) and broken replication forks. Loss of function of either p53 or HR leads to an increased risk of cancer. Given the importance of both p53 and HR in maintaining genomic integrity, we analyzed the effect of p53 on HR in vivo using Fluorescent Yellow Direct Repeat (FYDR) mice as well as with the sister chromatid exchange (SCE) assay. FYDR mice carry a direct repeat substrate in which an HR event can yield a fluorescent phenotype. Here, we show that p53 status does not significantly affect spontaneous HR in adult pancreatic ...
Introduction of new antibiotic resistance genes in the plasmids of interest is a frequent task in molecular cloning practice. Classical approaches involving digestion with restriction endonucleases and ligation are time-consuming. We have created a set of insertion vectors (pINS) carrying genes that provide resistance to various antibiotics (puromycin, blasticidin and G418) and containing a loxP site. Each vector (pINS-Puro, pINS-Blast or pINS-Neo) contains either a chloramphenicol or a kanamycin resistance gene and is unable to replicate in most E. coli strains as it contains a conditional R6Kγ replication origin. Introduction of the antibiotic resistance genes into the vector of interest is achieved by Cre-mediated recombination between the replication-incompetent pINS and a replication-competent target vector. The recombination mix is then transformed into E. coli and selected by the resistance marker (kanamycin or chloramphenicol) present in pINS, which allows to recover the recombinant plasmids
Free-living bacteria are usually thought to have large effective population sizes, and so tiny selective differences can drive their evolution. However, because recombination is infrequent, background selection against slightly deleterious alleles should reduce the effective population size (N e) by orders of magnitude. For example, for a well-mixed population with 10 12 individuals and a typical level of homologous recombination (r/m= 3, i.e., nucleotide changes due to recombination [r] occur at 3 times the mutation rate [m]), we predict that N e is,10 7. An argument for high N e values for bacteria has been the high genetic diversity within many bacterial species, but this diversity may be due to population structure: diversity across subpopulations can be far higher than diversity within a subpopulation, which makes it difficult to estimate N e correctly. Given an estimate ofN e, standard population genetics models imply that selection should be sufficient to drive evolution if N e ×s is ...
V(D)J recombination is initiated by lymphoid-specific recombination activating gene 1 (RAG1) and RAG2 proteins, which introduce DSBs precisely between immunoglobulin and T cell receptor (TCR) coding gene segments and flanking recombination signal sequences. RAG-mediated cleavage generates four broken-end intermediates: two blunt signal ends and two covalently closed coding hairpin ends (1). The subsequent resolution of V(D)J ends into coding and signal joints requires ubiquitously expressed factors that function in general DSB repair (2,3). Although V(D)J recombination generates DNA damage, it has been presumed that broken DNA intermediates, which associate with RAG proteins within a postcleavage synaptic complex (4, 5), are sequestered from the DNA damage surveillance machinery. Primary DNA damage sensors include histone H2AX, which becomes rapidly phosphorylated (γ-H2AX) in response to external damage (6, 7), and the MRE11/RAD50/NBS1 complex, which forms ionizing irradiation-induced foci at ...
Recombination between homologous, but non-allelic, stretches of DNA such as gene families, segmental duplications and repeat elements is an important source of mutation. In humans, recent studies have identified short DNA motifs that both determine the location of 40 per cent of meiotic cross-over hotspots and are significantly enriched at the breakpoints of recurrent non-allelic homologous recombination (NAHR) syndromes. Unexpectedly, the most highly penetrant form of the motif occurs on the background of an inactive repeat element family (THE1 elements) and the motif also has strong recombinogenic activity on currently active element families including Alu and LINE2 elements. Analysis of genetic variation among members of these repeat families indicates an important role for NAHR in their evolution. Given the potential for double-strand breaks within repeat DNA to cause pathological rearrangement, the association between repeats and hotspots is surprising. Here we consider possible explanations for
DNA-skadande ämnen är vanligt i cancerbehandling, då snabbt växande celler, såsom cancerceller är betydligt känsligare än normala celler för DNA skador. En grupp av ämnen som vanligen används i cancerbehandling är korsbindare av DNA. Dessa ämnen kommer reagera två gånger med DNA och skapa två bindningar mitt emot varandra. DNA strängen, som består av två delar, måste kunna separeras och kopieras (replikation) på ett tillförlitligt sätt för att cellerna ska kunna dela sig och bli flera. DNA strängen måste också kunna dela sig och bli avläst rätt för att nya proteiner ska kunna bildas (transkription). När korsbindarna har bundit till DNA strängarna, hindrar detta deras separation och därigenom förhindras även avläsningen och kopieringen. För att göra undersökningarna av DNA korsbindande ämnen ännu lite svårare, så ger korsbindare flera olika typer av skador. Dels kan det bli flera olika typer av korsbindningar, både mellan två DNA-strängar (ICL) vilket ...
17. Katagiri, T., Saito, H., Shinohara, A., Ogawa, H., Kamada, N., Nakamura Y. and Y. Miki. Multiple possible sites of BRCA2 interacting with DNA repair protein Rad51. Genes, Chromosomes and Cancer, 21, 217-222. 1998, CI=43.. 18. Gasior, S., Wang, A., Kohra, Y., Shinohara, A. and D.K. Bishop. Rad52 associates with RPA and functions with Rad55 and Rad57 to assemble meiotic recombination complexes. Genes & Dev., 12, 2208-2221, 1998, CI=183.. 19. Bishop, D.K., Ear, U., Bhattacharyya, A., Calderone, C., Beckett, M., Weichselbaum, R. and A. Shinohara. Xrcc3 is required for assembly of Rad51-complexes in vivo. J. Biol. Chem., 273, 21482-21488. 1998, CI=213.. 20. Takata, M., Sasaki, M., Sonoda, E., Morrison, C., Hashimoto, M., Utsumi, H., Yamaguchi-Iwai, Y., Shinohara, A., and S. Takeda. Homologous recombination and non-homologous end-joining pathways of DNA double-strand break repair have overlapping roles in maintenance of chromosome integrity. EMBO J., 17, 5497-5508. 1998, CI=797.. 21. Nishitani, ...
Homologous recombination (HR) is involved in the creation of genetic diversity, maintenance of chromosome structure, and restoration of DNA damage. In mammals, efficient repair of double-strand breaks and interstrand crosslinks requires activities of Rad51 (a RecA homolog) and the Rad51-related proteins: Rad51B (Rad51L1), Rad51C (Rad51L2), Rad51D (Rad51L3), Xrcc2, Xrcc3, and Dmc1. RAD51 family genes demonstrate alternative splicing, and approximately 45% amino acid similarity is shared among their full-length translation products. All Rad51 proteins contain Walker box motifs consistent with an ability to bind and hydrolyze ATP. Two distinct complexes, Rad51B-Rad51C-Rad51D-Xrcc2 and Rad51C-Xrcc3, participate in early and late HR. With exception of Dmc1, deletions of the Rad51 genes in mouse are lethal; however, failure of Rad51d-null cells to proliferate can be overcome by disruption of the Trp53 tumor suppressor gene. Initial studies described in this dissertation ascertained that ...
The construction of a delivery and clearing system for the generation of food-grade recombinant lactic acid bacterium strains, based on the use of an integrase (Int) and a resolvo-invertase (β-recombinase) and their respective target sites (attP-attB and six, respectively) is reported. The delivery system contains a heterologous replication origin and antibiotic resistance markers surrounded by two directly oriented six sites, a multiple cloning site where passenger DNA could be inserted (e.g., the cI gene of bacteriophage A2), the int gene, and the attP site of phage A2. The clearing system provides a plasmid-borne gene encoding β-recombinase. The nonreplicative vector-borne delivery system was transformed into Lactobacillus casei ATCC 393 and, by site-specific recombination, integrated as a single copy in an orientation- and Int-dependent manner into the attB site present in the genome of the host strain. The transfer of the clearing system into this strain, with the subsequent expression of ...
UNLABELLED: Phylogenetic inference in bacterial genomics is fundamental to understanding problems such as population history, antimicrobial resistance, and transmission dynamics. The field has been plagued by an apparent state of contradiction since the distorting effects of recombination on phylogeny were discovered more than a decade ago. Researchers persist with detailed phylogenetic analyses while simultaneously acknowledging that recombination seriously misleads inference of population dynamics and selection. Here we resolve this paradox by showing that phylogenetic tree topologies based on whole genomes robustly reconstruct the clonal frame topology but that branch lengths are badly skewed. Surprisingly, removing recombining sites can exacerbate branch length distortion caused by recombination. IMPORTANCE: Phylogenetic tree reconstruction is a popular approach for understanding the relatedness of bacteria in a population from differences in their genome sequences. However, bacteria frequently
TY - JOUR. T1 - Nuclear dynamics of the Set1C subunit Spp1 prepares meiotic recombination sites for break formation. AU - Karányi, Zsolt. AU - Halász, László. AU - Acquaviva, Laurent. AU - Jónás, Dávid. AU - Hetey, Szabolcs. AU - Boros‑Oláh, Beáta. AU - Peng, Feng. AU - Chen, Doris. AU - Klein, Franz. AU - Géli, Vincent. AU - Székvölgyi, Lóránt. PY - 2018/10/1. Y1 - 2018/10/1. N2 - Spp1 is the H3K4me3 reader subunit of the Set1 complex (COMPASS/Set1C) that contributes to the mechanism by which meiotic DNA break sites are mechanistically selected. We previously proposed a model in which Spp1 interacts with H3K4me3 and the chromosome axis protein Mer2 that leads to DSB formation. Here we show that spatial interactions of Spp1 and Mer2 occur independently of Set1C. Spp1 exhibits dynamic chromatin binding features during meiosis, with many de novo appearing and disappearing binding sites. Spp1 chromatin binding dynamics depends on its PHD finger and Mer2-interacting domain and on ...
Methods and compositions using populations of randomized modified FRT recombination sites to identify, isolate and/or characterize modified FRT recombination sites are provided. The recombinogenic mod
RAD54, a significant homologous recombination proteins, is an associate from the SWI2/SNF2 category of ATPase-dependent DNA translocases. as well as the role from the RAD54 ATPase activity with this activation is definitely controversial. Its been demonstrated that RAD54 forms a co-complex with RAD51-ssDNA filaments, stabilizing the filament in a fashion that is definitely self-employed of ATP hydrolysis by RAD54 (22, 25). Nevertheless, RAD54 mutants faulty in ATP hydrolysis neglect to stimulate RAD51 DNA strand exchange, indicating that extra downstream mechanisms are essential for the activation (14, 16, 26). Its been recommended that, through the seek out homology, binding of dsDNA by RAD54 and its own ATPase-dependent translocation along the RAD51-ssDNA filament may activate DNA strand exchange by either offering rapid delivery from the inbound dsDNA for the homology sampling by RAD51 or by locally disrupting the dsDNA foundation pairs, producing them available for the homology search from ...
Plasmids are important members of the bacterial mobile gene pool, and are among the most important contributors to horizontal gene transfer between bacteria. They typically harbour a wide spectrum of host beneficial traits, such as antibiotic resistance, inserted into their backbones. Although these inserted elements have drawn considerable interest, evolutionary information about the plasmid backbones, which encode plasmid related traits, is sparse. Here we analyse 25 complete backbone genomes from the broad-host-range IncP-1 plasmid family. Phylogenetic analysis reveals seven clades, in which two plasmids that we isolated from a marine biofilm represent a novel clade. We also found that homologous recombination is a prominent feature of the plasmid backbone evolution. Analysis of genomic signatures indicates that the plasmids have adapted to different host bacterial species. Globally circulating IncP-1 plasmids hence contain mosaic structures of segments derived from several parental plasmids that
Coordination between DNA replication and DNA repair ensures maintenance of genome integrity, which is lost in cancer cells. Lesions and discontinuities in the DNA template undergoing replication induce replication fork stalling. Homologous recombination (HR) proteins RAD51 and BRCA1/2 play a major role in the stability of replication forks. This function appears to be distinct from the classical one performed by these proteins in HR dependent DNA Double Strand Break repair.
TY - JOUR. T1 - A study of electron recombination using highly ionizing particles in the ArgoNeuT Liquid Argon TPC. AU - Acciarri, R.. AU - Adams, C.. AU - Asaadi, J.. AU - Baller, B.. AU - Bolton, T.. AU - Bromberg, C.. AU - Cavanna, F.. AU - Church, E.. AU - Edmunds, D.. AU - Ereditato, A.. AU - Farooq, S.. AU - Fleming, B.. AU - Greenlee, H.. AU - Horton-Smith, G.. AU - James, C.. AU - Klein, E.. AU - Lang, K.. AU - Laurens, P.. AU - McKee, D.. AU - Mehdiyev, R.. AU - Page, B.. AU - Palamara, O.. AU - Partyka, K.. AU - Rameika, G.. AU - Rebel, B.. AU - Soderberg, M.. AU - Spitz, J.. AU - Szelc, A. M.. AU - Weber, M.. AU - Wojcik, M.. AU - Yang, T.. AU - Zeller, G. P.. PY - 2013/8/1. Y1 - 2013/8/1. N2 - Electron recombination in highly ionizing stopping protons and deuterons is studied in the ArgoNeuT detector. The data are well modeled by either a Birks model or a modified form of the Box model. The dependence of recombination on the track angle with respect to the electric field direction is ...