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Diversidade genética em populações de Plasmodium vivax: análise de marcadores genéticos neutros e de genes potencialmente associados à resistência a drogas.; Genetic diversity of Plasmodium vivax populations: analysis of neutral genetic markers and genes potentially associated with drug resistance.

Sanchez, Pamela Orjuela
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 30/07/2010 PT
Relevância na Pesquisa
46.09%
Através da análise de microssatélites e SNPs, incluindo tanto marcadores neutros como sujeitos a seleção, neste trabalho se demonstrou que: 1) As populações brasileiras de P. vivax (Pv) são mais diversas que as populações simpátricas de P. falciparum (Pf), porém ambas apresentam desequilíbrio de ligação. 2) Os polimorfismos neutros apresentam alta variabilidade ao longo do tempo em ambas as espécies, em contraste com a estabilidade observada nos marcadores sob seleção. 3) As altas taxas de recorrências por Pv na Amazônia brasileira são causadas, em sua maioria, por parasitas geneticamente não relacionados. 4) A recombinação não meiótica contribui substancialmente à diversidade dos domínios repetitivos de PvCSP. 5) Os SNPs nos genes pvmdr1 e pvcrt-o de isolados de Pv resistentes à cloroquina não se associam ao seu fenótipo in vivo. Finalmente, através da genotipagem de 57 SNPs do cromossomo 8 de Pv em 234 isolados do Brasil e da Ásia observou-se que, em Pv, a diversidade e a recombinação mitótica não se associam aos níveis de endemicidade como acontece em Pf e que Pv apresenta estrutura populacional continental e subcontinental no Brasil.; Through the analysis of microsatellites and SNPs, including both neutral and under selection markers...

A Bayesian approach for constructing genetic maps when markers are miscoded

Rosa, Guilherme J. M.; Yandell, Brian S.; Gianola, Daniel
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 353-369
ENG
Relevância na Pesquisa
46.1%
The advent of molecular markers has created opportunities for a better understanding of quantitative inheritance and for developing novel strategies for genetic improvement of agricultural species, using information on quantitative trait loci (QTL). A QTL analysis relies on accurate genetic marker maps. At present, most statistical methods used for map construction ignore the fact that molecular data may be read with error. Often, however, there is ambiguity about some marker genotypes. A Bayesian MCMC approach for inferences about a genetic marker map when random miscoding of genotypes occurs is presented, and simulated and real data sets are analyzed. The results suggest that unless there is strong reason to believe that genotypes are ascertained without error, the proposed approach provides more reliable inference on the genetic map.

Análise da variação cariotípica e dos mecanismos de recombinação em leveduras industriais (Saccharomyces cerevisiae) durante o processo de fermentação alcoólica; Analysis of the karyotypic variation and the recombination mechanisms industrial yeast (Saccharomyces cerevisiae) during the alcoholic fermentation process

Fabiana de Melo Duarte
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/08/2010 PT
Relevância na Pesquisa
36.27%
O etanol de cana-de-açúcar brasileiro ocupa um lugar de destaque entre as alternativas energéticas disponíveis atualmente. No processo fermentativo de produção de etanol é utilizada a levedura Saccharomyces cerevisiae, com destaque para a linhagem industrial PE-2, utilizada por cerca de 30% das usinas brasileiras, o que representa 10% da produção mundial. Essa linhagem associa uma alta eficiência na produção de etanol com uma excelente capacidade de adaptação ao ambiente altamente hostil e competitivo das dornas de fermentação. O nosso grupo de pesquisa realizou previamente uma caracterização genética e molecular detalhada de uma linhagem diplóide derivada diretamente de PE-2 (JAY270), o que forneceu inúmeras possibilidades para a manipulação genética dessa levedura com o objetivo de desenvolver linhagens mais produtivas. No entanto, alguns estudos observaram a ocorrência de variação cariotípica nessa linhagem durante o processo fermentativo, o que pode representar uma barreira para a manipulação dessa levedura. Sendo assim, é extremamente importante estudar o comportamento do genoma dessa linhagem durante a produção de etanol. Este projeto de Mestrado teve como objetivo principal a determinação do mecanismo de recombinação genética responsável pela geração de rearranjos cromossômicos na linhagem JAY270 durante a produção de etanol. Foi realizado um experimento de fermentação em escala semi-industrial iniciado com um inóculo puro de JAY270...

First report of recombination in Potato yellow vein virus (PYVV) in Colombia

Chaves-Bedoya,Giovanni; Cubillos,Karen; Guzmán-Barney,Mónica
Fonte: Sociedade Brasileira de Fitopatologia Publicador: Sociedade Brasileira de Fitopatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
Relevância na Pesquisa
36.22%
Potato yellow vein virus (PYVV) is currently one of the most important viruses that infects potatoes in Colombia and other Andean countries, causing losses in the production of tubers ranging from 25% to 50%. This study analyzed the genetic variability of different viral isolates collected in the department of Nariño, Colombia, through bioinformatics analysis of the sequences of three genes encoding the capsid protein (CP), the heat-shock protein 70 (Hsp70) and the minor capsid protein (CPm). We found that CPm is the gene that shows greater diversity, with higher values of nucleotide substitution and evidence of recombination. Based on an analysis of the haplotype map using nucleotide sequences of the CPm, we propose a model of putative recombination in this genomic region. The non-recombinant segments are supported by the results of the program GARD (Genetic Algorithm for Recombination Detection), phylogenetic trees and the paired values of genetic distances of each non-recombinant segments. The model clearly shows that the amino region of the CPm is prone to recombination. To our knowledge, this is the first report of genetic recombination as an evolutionary strategy in the CPm of PYVV.

Evaluation of methods for detecting recombination from DNA sequences: Computer simulations

Posada, David; Crandall, Keith A.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 20/11/2001 EN
Relevância na Pesquisa
36.23%
Recombination is a key evolutionary process that shapes the architecture of genomes and the genetic structure of populations. Although many statistical methods are available for the detection of recombination from DNA sequences, their absolute and relative performance is still unknown. Here we evaluated the performance of 14 different recombination detection algorithms. We used the coalescent with recombination to simulate DNA sequences with different levels of recombination, genetic diversity, and rate variation among sites. Recombination detection methods were applied to these data sets, and whether they detected or not recombination was recorded. Different recombination methods showed distinct performance depending on the amount of recombination, genetic diversity, and rate variation among sites. The model of nucleotide substitution under which the data were generated did not seem to have a significant effect. Most methods increase power with more sequence divergence. In general, recombination detection methods seem to capture the presence of recombination, but they are not very powerful. Methods that use substitution patterns or incompatibility among sites were more powerful than methods based on phylogenetic incongruence. Most methods do not seem to infer more false positives than expected by chance. Especially depending on the amount of diversity in the data...

Comparison of the Genetic Recombination Rates of Human Immunodeficiency Virus Type 1 in Macrophages and T Cells†

Chen, Jianbo; Rhodes, Terence D.; Hu, Wei-Shau
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2005 EN
Relevância na Pesquisa
36.23%
Human immunodeficiency virus type 1 (HIV-1) exhibits a high level of genetic variation generated by frequent mutation and genetic recombination during reverse transcription. We have measured HIV-1 recombination rates in T cells in one round of virus replication. It was recently proposed that HIV-1 recombines far more frequently in macrophages than in T cells. In an attempt to delineate the mechanisms that elevate recombination, we measured HIV-1 recombination rates in macrophages at three different marker distances. Surprisingly, the recombination rates were comparable in macrophages and in T cells. In addition, we observed similar recombination rates in two monocytic cell lines regardless of the differentiation status. These results indicate that HIV-1 undergoes similar numbers of recombination events when infecting macrophages and T cells.

High Frequency of Genetic Recombination Is a Common Feature of Primate Lentivirus Replication

Chen, Jianbo; Powell, Douglas; Hu, Wei-Shau
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /10/2006 EN
Relevância na Pesquisa
36.22%
Recent studies indicate that human immunodeficiency virus type 1 (HIV-1) recombines at exceedingly high rates, approximately 1 order of magnitude more frequently than simple gammaretroviruses such as murine leukemia virus and spleen necrosis virus. We hypothesize that this high frequency of genetic recombination is a common feature of primate lentiviruses. Alternatively, it is possible that HIV-1 is unique among primate lentiviruses in possessing high recombination rates. Among other primate lentiviruses, only the molecular mechanisms of HIV-2 replication have been extensively studied. There are reported differences between the replication mechanisms of HIV-1 and those of HIV-2, such as preferences for RNA packaging in cis and properties of reverse transcriptase and RNase H activities. These biological disparities could lead to differences in recombination rates between the two viruses. Currently, HIV-1 is the only primate lentivirus in which recombination rates have been measured. To test our hypothesis, we established recombination systems to measure the recombination rates of two other primate lentiviruses, HIV-2 and simian immunodeficiency virus from African green monkeys (SIVagm), in one round of viral replication. We determined that...

Coinfection with Two Closely Related Alphaherpesviruses Results in a Highly Diversified Recombination Mosaic Displaying Negative Genetic Interference ▿

Muylkens, Benoît; Farnir, Frédéric; Meurens, François; Schynts, Frédéric; Vanderplasschen, Alain; Georges, Michel; Thiry, Etienne
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.28%
Phylogenetic studies of the emergence and spread of natural recombinants in herpesviruses infecting humans and animals have been reported recently. However, despite an ever-increasing amount of evidence of recombination in herpesvirus history, the recombination process and the consequences on the genetic diversity of the progeny remain poorly characterized. We addressed this issue by using multiple single-nucleotide polymorphisms (SNPs) differentiating the two subtypes of an alphaherpesvirus, bovine herpesvirus 1 (BoHV-1). Analysis of a large sample of progeny virions obtained in a single growth cycle of coinfected BoHV-1 strains provided a prospective investigation of the recombination dynamics by using SNPs as recombination markers. We found that the simultaneous infection with two closely related herpesviruses results in a highly diversified recombination mosaic. From the analysis of multiple recombinants arising in the progeny, we provide the first evidence of genetic interference influencing the recombination process in herpesviruses. In addition, we report striking differences in the levels of recombination frequency observed along the BoHV-1 genome. With particular emphasis on the genetic structure of a progeny virus population rising in vitro...

Analysis of Genetic Diversity and Sites of Recombination in Human Rhinovirus Species C▿

McIntyre, Chloe L.; McWilliam Leitch, E. Carol; Savolainen-Kopra, Carita; Hovi, Tapani; Simmonds, Peter
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.22%
Human rhinoviruses (HRVs) are a highly prevalent and diverse group of respiratory viruses. Although HRV-A and HRV-B are traditionally detected by virus isolation, a series of unculturable HRV variants have recently been described and assigned as a new species (HRV-C) within the picornavirus Enterovirus genus. To investigate their genetic diversity and occurrence of recombination, we have performed comprehensive phylogenetic analysis of sequences from the 5′ untranslated region (5′ UTR), VP4/VP2, VP1, and 3Dpol regions amplified from 89 HRV-C-positive respiratory samples and available published sequences. Branching orders of VP4/VP2, VP1, and 3Dpol trees were identical, consistent with the absence of intraspecies recombination in the coding regions. However, numerous tree topology changes were apparent in the 5′ UTR, where >60% of analyzed HRV-C variants showed recombination with species A sequences. Two recombination hot spots in stem-loop 5 and the polypyrimidine tract in the 5′ UTR were mapped using the program GroupingScan. Available HRV-C sequences showed evidence for additional interspecies recombination with HRV-A in the 2A gene, with breakpoints mapping precisely to the boundaries of the C-terminal domain of the encoded proteinase. Pairwise distances between HRV-C variants in VP1 and VP4/VP2 regions fell into two separate distributions...

Extensive Recombination-Induced Disruption of Genetic Interactions Is Highly Deleterious but Can Be Partially Reversed by Small Numbers of Secondary Recombination Events

Monjane, Adérito L.; Martin, Darren P.; Lakay, Francisco; Muhire, Brejnev M.; Pande, Daniel; Varsani, Arvind; Harkins, Gordon; Shepherd, Dionne N.; Rybicki, Edward P.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2014 EN
Relevância na Pesquisa
36.27%
Although homologous recombination can potentially provide viruses with vastly more evolutionary options than are available through mutation alone, there are considerable limits on the adaptive potential of this important evolutionary process. Primary among these is the disruption of favorable coevolved genetic interactions that can occur following the transfer of foreign genetic material into a genome. Although the fitness costs of such disruptions can be severe, in some cases they can be rapidly recouped by either compensatory mutations or secondary recombination events. Here, we used a maize streak virus (MSV) experimental model to explore both the extremes of recombination-induced genetic disruption and the capacity of secondary recombination to adaptively reverse almost lethal recombination events. Starting with two naturally occurring parental viruses, we synthesized two of the most extreme conceivable MSV chimeras, each effectively carrying 182 recombination breakpoints and containing thorough reciprocal mixtures of parental polymorphisms. Although both chimeras were severely defective and apparently noninfectious, neither had individual movement-, encapsidation-, or replication-associated genome regions that were on their own “lethally recombinant.” Surprisingly...

Distribuição de taxas de recombinação ao longo do cromossomo 4 de Arabidopsis thaliana e sua associação com elementos genômicos; Distribution of recombination rates across the chromosome 4 of Arabidopsis thaliana and its association with genomic features

MARTINS, Adilson Santos
Fonte: Universidade Federal de Goiás; BR; UFG; Doutorado em Agronomia; Ciências Agrárias Publicador: Universidade Federal de Goiás; BR; UFG; Doutorado em Agronomia; Ciências Agrárias
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
36.25%
Recombination is one of the most important factors in the evolution of genome organization. It provides the links between homologous chromosomes that ensure their proper segregation during the first meiotic division. It is responsible for the creation of novel allele combinations and yields genetic diversity on which evolutionary selection can act. Double-strand DNA breaks (DSB) initiate meiotic recombination and when the 3 terminus of one of the broken strands invades the unbroken DNA molecule and primes DNA synthesis a double Holliday junction must be resolved through some alternative pathways. When homologous chromosomes exchange genetic material with each other, an event of recombination or a crossover takes place, which may be seen through chiasma. Citological, genetics, and molecular studies in many organisms have demonstrated that crossovers have a non homogeneous distribution across chromosomes, and rather concentrated in relative small DNA fragments usually called recombination hotspots. In searching for genomic features associated with recombination hotspots a model fitted to human genome data explained 42% of recombination rate variation in a 5 mega base pairs scale. Despite the fact that genomes of some plant species have been already sequenced...

A whole genome scan for differences in recombination rates among three Bos taurus breeds

Thomsen, H.; Reinsch, N.; Xu, N.; Bennewitz, J.; Looft, C.; Grupe, S.; Kuhn, C.; Brockmann, G.; Schwerin, M.; Leyhe-Horn, B.; Hiendleder, S.; Erhardt, G.; Medjugorac, I.; Russ, I.; Forster, M.; Brenig, B.; Reinhardt, F.; Reents, R.; Blumel, J.; Averdunk,
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2001 EN
Relevância na Pesquisa
46.21%
Twenty paternal half-sib families of a granddaughter design were genotyped for 265 genetic markers, most of them microsatellites. These were 16 Holstein families, 3 Simmental families, and 1 Brown Swiss family. The number of sires per breed was 872, 170, and 32, respectively. Two-point recombination rates were estimated both jointly for all breeds and each single breed separately. Of 1168 marker intervals, 865 provided estimates for at least two breeds. Differences between breeds were tested by likelihood ratio tests. Four marker intervals, representing three genomic regions on BTA19, BTA24, and BTA27, show a significant impact of the breed at a false discovery rate of 0.23 and indicate a genetic component of observed heterogeneity of recombination. The variability of recombination rates between cattle breeds might not be a common feature of the whole genome, but rather might be restricted to certain chromosomal segments. Thus, attention should be paid to heterogeneities when pooling data of such regions from different breeds.; Hauke Thomsen, Norbert Reinsch, Ningying Xu, Jörn Bennewitz, Christian Looft, Sven Grupe, Christa Kühn, Gudrun A. Brockmann, Manfred Schwerin, Birgit Leyhe-Horn, Stefan Hiendleder, Georg Erhardt, Ivica Medjugorac...

The N-terminal 12 amino acids of tomato aspermy virus 2b protein function in infection and recombination

Shi, B.J.; Palukaitis, P.
Fonte: Soc General Microbiology Publicador: Soc General Microbiology
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
45.98%
The roles for various regions of the 2b protein in infection, hypervirulence and recombination were examined by introducing stop codons in a chimeric virus containing RNA 1 from the cucumber mosaic virus (CMV strain Q), RNA 3 from the tomato aspermy virus (TAV) and RNA 2 of CMV with a 2b gene from TAV. Chimeric virus expressing the intact 2b protein induced severe symptoms in inoculated Nicotiana clevelandii and Nicotiana glutinosa and facilitated CMV–TAV recombination, while chimeric viruses not expressing 2b protein did not infect plants systemically. Chimeric viruses expressing either the N-terminal 43 or 12 aa of the 2b protein infected both plant species systemically and facilitated CMV–TAV recombination, but induced mild symptoms and no symptoms in the infected plants, respectively. These data suggest that oligopeptides can have important functions in the biology of viruses and prompt a re-examination of existing small ORFs in sequenced virus genomes.; Bu-Jun Shi and Peter Palukaitis

Copy-number gains of HUWE1 due to replication-and recombination-based rearrangements

Froyen, G.; Belet, S.; Martinez, F.; Santos-Reboucas, C.; Declercq, M.; Verbeeck, J.; Donckers, L.; Berland, S.; Mayo, S.; Rosello, M.; Pimentel, M.; Fintelman-Rodrigues, N.; Hovland, R.; dos Santos, S.; Raymond, F.; Sundernathan, T.; Corbett, M.; Sheffie
Fonte: Univ Chicago Press Publicador: Univ Chicago Press
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
45.95%
We previously reported on nonrecurrent overlapping duplications at Xp11.22 in individuals with nonsyndromic intellectual disability (ID) harboring HSD17B10, HUWE1, and the microRNAs miR-98 and let-7f-2 in the smallest region of overlap. Here, we describe six additional individuals with nonsyndromic ID and overlapping microduplications that segregate in the families. High-resolution mapping of the 12 copy-number gains reduced the minimal duplicated region to the HUWE1 locus only. Consequently, increased mRNA levels were detected for HUWE1, but not HSD17B10. Marker and SNP analysis, together with identification of two de novo events, suggested a paternally derived intrachromosomal duplication event. In four independent families, we report on a polymorphic 70 kb recurrent copy-number gain, which harbors part of HUWE1 (exon 28 to 3′ untranslated region), including miR-98 and let-7f-2. Our findings thus demonstrate that HUWE1 is the only remaining dosage-sensitive gene associated with the ID phenotype. Junction and in silico analysis of breakpoint regions demonstrated simple microhomology-mediated rearrangements suggestive of replication-based duplication events. Intriguingly, in a single family, the duplication was generated through nonallelic homologous recombination (NAHR) with the use of HUWE1-flanking imperfect low-copy repeats...

Clonality and α-a recombination in the Australian Cryptococcus gattii VGII population - an emerging outbreak in Australia; Clonality and alpha-a recombination in the Australian Cryptococcus gattii VGII population - an emerging outbreak in Australia

Carriconde, F.; Gilgado, F.; Arthur, I.; Ellis, D.; Malik, R.; van de Wiele, N.; Robert, V.; Currie, B.J.; Meyer, W.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
46.2%
BACKGROUND: Cryptococcus gattii is a basidiomycetous yeast that causes life-threatening disease in humans and animals. Within C. gattii, four molecular types are recognized (VGI to VGIV). The Australian VGII population has been in the spotlight since 2005, when it was suggested as the possible origin for the ongoing outbreak at Vancouver Island (British Columbia, Canada), with same-sex mating being suggested as the driving force behind the emergence of this outbreak, and is nowadays hypothesized as a widespread phenomenon in C. gattii. However, an in-depth characterization of the Australian VGII population is still lacking. The present work aimed to define the genetic variability within the Australian VGII population and determine processes shaping its population structure. METHODOLOGY/PRINCIPAL FINDINGS: A total of 54 clinical, veterinary and environmental VGII isolates from different parts of the Australian continent were studied. To place the Australian population in a global context, 17 isolates from North America, Europe, Asia and South America were included. Genetic variability was assessed using the newly adopted international consensus multi-locus sequence typing (MLST) scheme, including seven genetic loci: CAP59, GPD1, LAC1...

Local-scale patterns of genetic variability, outcrossing, and spatial structure in natural stands of Arabidopsis thaliana

Bomblies, Kirsten; Yant, Levi; Laitinen, Roosa A.; Kim, Sang-Tae; Hollister, Jesse D.; Warthmann, Norman; Fitz, Joffrey; Weigel, Detlef
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 14 pages
Relevância na Pesquisa
46.07%
As Arabidopsis thaliana is increasingly employed in evolutionary and ecological studies, it is essential to understand patterns of natural genetic variation and the forces that shape them. Previous work focusing mostly on global and regional scales has demonstrated the importance of historical events such as long-distance migration and colonization. Far less is known about the role of contemporary factors or environmental heterogeneity in generating diversity patterns at local scales. We sampled 1,005 individuals from 77 closely spaced stands in diverse settings around Tübingen, Germany. A set of 436 SNP markers was used to characterize genome-wide patterns of relatedness and recombination. Neighboring genotypes often shared mosaic blocks of alternating marker identity and divergence. We detected recent outcrossing as well as stretches of residual heterozygosity in largely homozygous recombinants. As has been observed for several other selfing species, there was considerable heterogeneity among sites in diversity and outcrossing, with rural stands exhibiting greater diversity and heterozygosity than urban stands. Fine-scale spatial structure was evident as well. Within stands, spatial structure correlated negatively with observed heterozygosity...

Integration of transcript and genetic maps of chromosome 16 at near-1-Mb resolution: demonstration of a 'hot-spot' for recombination at 16p12

Callen, D.; Lane, S.; Kozman, H.; Kremmidiotis, G.; Whitmore, S.; Lowenstein, M.; Doggett, N.; Kenmochi, N.; Page, D.; Maglott, D.; Nierman, W.; Murakawa, K.; Sikela, J.; Houlgatte, R.; Auffray, C.; Sutherland, G.
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Publicado em //1995 EN
Relevância na Pesquisa
46.14%
A single mapping resource, a mouse/human somatic cell panel with average distance between breakpoints of 1.2 Mb and a potential resolution of 1 Mb, has been utilized to integrate the genetic map and a transcript map of human chromosome 16. This map includes 141 genetic markers and 200 genes and transcripts. The localization of four genes (CHEL3, TK2, TRG1, and MMP9) reported to map to chromosome 16 could not be confirmed, and for three of these localizations to other human chromosomes are reported. A correlation between genetic and physical distance over a region estimated to be 23 Mb on the short arm of chromosome 16 identified an interval demonstrating a greatly increased rate of recombination where, in females, 1 cM is equivalent to a physical distance of 100 kb.

Detecting Genetic Recombination

Weiller, Georg
Fonte: Humana Press Inc. Publicador: Humana Press Inc.
Tipo: Parte de Livro
Relevância na Pesquisa
46.18%
Recombination is the major motor of evolution. While mutations result in gradual changes, recombination reshuffles entire functional modules and thus progresses evolution in leaps and bounds. We need to identify recombination breakpoints in sequences to u

Generation of Food-Grade Recombinant Lactic Acid Bacterium Strains by Site-Specific Recombination

Martín, M. Cruz; Alonso, Juan Carlos; Suárez Fernández, Juan Evaristo; Álvarez González, Miguel Ángel
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
Relevância na Pesquisa
45.9%
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 the β-recombinase, led to site-specific DNA resolution of the non-food-grade DNA. These methods were validated by the construction of a stable food-grade L. casei ATCC 393-derived strain completely immune to phage A2 infection during milk fermentation.; This work was supported by grant BIO4-CT96-0402 to J.E.S. and grants PB 96-0817 and BIO4-CT98-0250 to J.C.A.; Peer reviewed

Causes and Consequences of Recombination Rate Variation in Drosophila

Stevison, Laurie S.
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
Relevância na Pesquisa
36.34%

Recombination occurs during meiosis to produce new allelic combinations in natural populations, and thus strongly affects evolutionary processes. The model system Drosophila has been crucial for understanding the mechanics underlying recombination and assessing the association between recombination rate and several evolutionary parameters. Drosophila was the first system in which genetic maps were developed using recombination frequencies between genes. Further, Drosophila has been used to determine genetic and environmental conditions that cause variation in recombination rate. Finally, Drosophila has been instrumental in elucidating associations between local recombination rate and nucleotide diversity, divergence and codon bias, as well as helping determine the causes of these associations.

Here I present a fine-scale map of recombination rates across two major chromosomes in Drosophila persimilis using 181 SNP markers spanning two of five major chromosome arms. Using this map, I report significant fine-scale heterogeneity of local recombination rates. However, I also observed "recombinational neighborhoods", where adjacent intervals had similar recombination rates after excluding regions near the centromere and telomere. I further found significant positive associations of fine-scale recombination rate with repetitive element abundance and a 13-bp sequence motif known to associate with human recombination rates. I noted strong crossover interference extending 5-7 Mb from the initial crossover event. Further...