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Epistasis among eNOS, MMP-9 and VEGF maternal genotypes in hypertensive disorders of pregnancy

Luizon, Marcelo Rizzatti; Sandrim, Valéria Cristina; Palei, Ana Carolina Taveiros; Lacchini, Riccardo; Cavalli, Ricardo de Carvalho; Duarte, Geraldo; Santos, Jose Eduardo Tanus dos
Fonte: NATURE PUBLISHING GROUP; LONDON Publicador: NATURE PUBLISHING GROUP; LONDON
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.89%
Polymorphisms of the endothelial nitric oxide synthase (eNOS), matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) genes were shown to be associated with hypertensive disorders of pregnancy. However, epistasis is suggested to be an important component of the genetic susceptibility to preeclampsia (PE). The aim of this study was to characterize the interactions among these genes in PE and gestational hypertension (GH). Seven clinically relevant polymorphisms of eNOS (T-786C, rs2070744, a variable number of tandem repeats in intron 4 and Glu298Asp, rs1799983), MMP-9 (C-1562T, rs3918242 and -90(CA)(13-25), rs2234681) and VEGF (C-2578A, rs699947 and G-634C, rs2010963) were genotyped by TaqMan allelic discrimination assays or PCR and fragment separation by electrophoresis in 122 patients with PE, 107 patients with GH and a control group of 102 normotensive pregnant (NP) women. A robust multifactor dimensionality reduction analysis was used to characterize gene-gene interactions. Although no significant genotype combinations were observed for the comparison between the GH and NP groups (P>0.05), the combination of MMP-9-1562CC with VEGF-634GG was more frequent in NP women than in women with PE (P<0.05). Moreover...

Epistasia e interação epistasia por locais para a produção de grãos em soja; Epistasis and epistasis by location interaction for grain yield in soybean

Acevedo Barona, Marco Antonio
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 10/12/2007 PT
Relevância na Pesquisa
37.4%
Nos programas de melhoramentos de soja as progênies endogâmicas são frequentemente avaliadas como possíveis cultivares. O estudo da estrutura da variação genética entre progênies de diferentes gerações de autofecundação depende da ação dos locos envolvidos e da variação do caráter sob estudo. Em soja o caráter produção de grãos (PG) é considerado o de maior importância econômica e destaca-se por apresentar herança quantitativa e ser altamente influenciada pelo ambiente. As estratégias de seleção utilizadas para o desenvolvimento de cultivares em soja poderiam ser otimizadas através do estudo da importância relativa dos componentes de variância, particularmente a proporção de variação devida à interação não alélica (epistasia). Com o objetivo de estudar a variação epistática e sua interação com ambientes (locais) para a produção de grãos em soja utilizou-se o delineamento "Triple Test Cross Modificado" (TTC) de JINKS, PERKINS e BREESE (1969). Uma amostra de 32 linhagens (Pi) derivadas de um cruzamento biparental foi cruzada com duas linhagens divergentes (L1 e L2) contrastantes para PG, derivadas da mesma população (testadores). Os experimentos de avaliação foram conduzidos no ano agrícola de 2006/2007 em dois locais (Piraciacaba e Anhembi) em delineamentos em látice triplo 10 x 10. Os tratamentos correspondiam aos 32 cruzamentos Pi x L1...

Epistasia em testecrosses de milho; Epistasis in maize testcrosses

Silva, Diego Velásquez Faleiro e
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 12/08/2011 PT
Relevância na Pesquisa
37.4%
A epistasia já é conhecida desde o início dos estudos em genética, porém sua contribuição para as estimativas dos componentes da variância genética e para o melhoramento genético ainda não é bem entendida. A maioria dos modelos usados para estudar a herança dos caracteres quantitativos considera apenas os efeitos genéticos aditivos e de dominância, assumindo ausência da epistasia, mesmo que as análises não forneçam testes para tal suposição. Portanto, na sua presença, estimativas de variância aditiva e dominância, coeficientes de herdabilidade e respostas esperadas com a seleção estão viesadas. Os objetivos deste estudo foram: (i) verificar se a epistasia está presente na expressão de diversos caracteres em testecrosses; (ii) estimar os efeitos epistáticos em cada planta 2 F para estes caracteres; e (iii) verificar se a epistasia interage com ambientes e testadores. Uma população de 100 progênies F2:3 foi obtida do cruzamento das linhagens endogâmicas L-08-05F e L-38-05D e foram retrocruzadas com as linhagens parentais e sua geração 1 F , conforme o delineamento triple test cross. As 300 progênies de retrocruzamento foram cruzadas com as linhagens testadoras L-02-03D e L-04-05F. Os testecrosses obtidos foram avaliados em dez ambientes no município de Piracicaba...

Variantes genéticas de risco para a dependência de crack/cocaína: estudo de associação do tipo gene candidato e epistasia; Genetic risk variants for crack/cocaine dependence:gene candidate association study and epistasis

Negrão, André Brooking
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 19/03/2012 PT
Relevância na Pesquisa
36.89%
O uso da cocaína e do crack tornou-se um problema de saúde pública importante no Brasil por conta de prejuízos significativos do ponto de vista médico, psicológico e social que ele acarreta. Estudos de gêmeos e, em famílias, sugerem que a dependência de cocaína é uma doença complexa, com participação importante de fatores genéticos. Os estudos genéticos sobre usuários de cocaína são poucos e padecem de problemas metodológicos, tais como, amostras pequenas, com alto grau de miscigenação populacional e um número limitado de marcadores genéticos pesquisados. Além disto, há pouco sendo feito no sentido de verificar como os genes já associados à dependência de cocaína interagem entre si, ou seja, de investigações sobre a epistasia genética. Com o intuito de aprofundar a investigação dos aspectos biológicos da dependência de cocaína, nós estudamos, através de um estudo casocontrole, uma amostra de inicial de 746 pacientes dependentes de crack/cocaína hospitalizados em clínicas especializadas para o tratamento de dependência química na cidade de São Paulo, que foram comparados a 891 controles normais, sem história prévia de abuso ilegal de substâncias. Os objetivos desta tese foram: 1) verificar a associação de três polimorfismos (rs1803274...

Epistasia na herança da resistência do milho ao gorgulho Sitophilus zeamais (Coleoptera: Curculionidae); Epistasis in the inheritance of maize resistance to Sitophilus zeamais (Coleoptera: Curculionidae)

Morais, Alexandre Augusto de
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 14/08/2012 PT
Relevância na Pesquisa
37.4%
Considerado um dos aspectos mais complexos da genética quantitativa, a epistasia tem sido ignorada pelos melhoristas nos estudos de herança dos caracteres, principalmente os da herança da resistência de plantas a insetos, que são de difícil obtenção. No milho, a principal praga de grãos é o Sitophilus zeamais (Coleoptera: Curculionidae), devido a sua capacidade de atacar grãos tanto no campo quanto em silos. Contudo, as estimativas dos componentes aditivo e de dominância envolvidos na herança dessa resistência podem estar viesadas pela presença do efeito da epistasia. Utilizando o delineamento triple testcross, os objetivos deste trabalho foram: (i) verificar a presença da epistasia para os caracteres relacionados à resistência do milho ao S. zeamais; (ii) estimar os efeitos epistáticos em cada planta F2; e (iii) estimar o efeito da interação epistasia x ambientes para estes caracteres. As 300 progênies de retrocruzamentos utilizadas nesse estudo foram avaliadas em dois ambientes no município de Piracicaba/SP, em delineamento alfa-látice 15 x 20, no esquema fatorial com duas repetições por ambiente. Os caracteres avaliados foram: número de insetos mortos (NM); número de insetos emergidos (EM); tempo médio de desenvolvimento dos insetos (TM); índice de suscetibilidade (IS) e perda percentual de massa seca dos grãos (PE). No ambiente E. E. Anhumas a presença da epistasia foi detectada para todos os caracteres; porém...

Epistasis among eNOS, MMP-9 and VEGF maternal genotypes in hypertensive disorders of pregnancy

Luizon, Marcelo R.; Sandrim, Valeria C.; Palei, Ana C. T.; Lacchini, Riccardo; Cavalli, Ricardo C.; Duarte, Geraldo; Tanus-Santos, Jose E.
Fonte: Nature Publishing Group; London Publicador: Nature Publishing Group; London
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.89%
Polymorphisms of the endothelial nitric oxide synthase (eNOS), matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) genes were shown to be associated with hypertensive disorders of pregnancy. However, epistasis is suggested to be an important component of the genetic susceptibility to preeclampsia (PE). The aim of this study was to characterize the interactions among these genes in PE and gestational hypertension (GH). Seven clinically relevant polymorphisms of eNOS (T-786C, rs2070744, a variable number of tandem repeats in intron 4 and Glu298Asp, rs1799983), MMP-9 (C-1562T, rs3918242 and -90(CA)(13-25), rs2234681) and VEGF (C-2578A, rs699947 and G-634C, rs2010963) were genotyped by TaqMan allelic discrimination assays or PCR and fragment separation by electrophoresis in 122 patients with PE, 107 patients with GH and a control group of 102 normotensive pregnant (NP) women. A robust multifactor dimensionality reduction analysis was used to characterize gene-gene interactions. Although no significant genotype combinations were observed for the comparison between the GH and NP groups (P>0.05), the combination of MMP-9-1562CC with VEGF-634GG was more frequent in NP women than in women with PE (P<0.05). Moreover...

Epistasis and genotype-by-environment interaction of grain protein content in durum wheat

Bnejdi,Fethi; Gazzah,Mohamed El
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
36.89%
Parental, F1, F2, BC1 and BC2 generations of four crosses involving four cultivars of durum wheat (Triticum durum Desf.) were evaluated at two sites in Tunisia. A three-parameter model was found inadequate for all cases except crosses Chili x Cocorit 71 at site Sidi Thabet and Inrat 69 x Karim at both sites. In most cases a digenic epistatic model was sufficient to explain variation in generation means. Dominance effects (h) and additive x additive epistasis (i) (when significant) were more important than additive (d) effects and other epistatic components. Considering the genotype-by-environment interaction, the non-interactive model (m, d, h, e) was found adequate. Additive variance was higher than environmental variance in three crosses at both sites. The estimated values of narrow-sense heritability were dependent upon the cross and the sites and were 0%-85%. The results indicate that appropriate choice of environment and selection in later generations would increase grain protein content in durum wheat.

Epistasis interaction of QTL effects as a genetic parameter influencing estimation of the genetic additive effect

Bocianowski,Jan
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
37.3%
Epistasis, an additive-by-additive interaction between quantitative trait loci, has been defined as a deviation from the sum of independent effects of individual genes. Epistasis between QTLs assayed in populations segregating for an entire genome has been found at a frequency close to that expected by chance alone. Recently, epistatic effects have been considered by many researchers as important for complex traits. In order to understand the genetic control of complex traits, it is necessary to clarify additive-by-additive interactions among genes. Herein we compare estimates of a parameter connected with the additive gene action calculated on the basis of two models: a model excluding epistasis and a model with additive-by-additive interaction effects. In this paper two data sets were analysed: 1) 150 barley doubled haploid lines derived from the Steptoe x Morex cross, and 2) 145 DH lines of barley obtained from the Harrington x TR306 cross. The results showed that in cases when the effect of epistasis was different from zero, the coefficient of determination was larger for the model with epistasis than for the one excluding epistasis. These results indicate that epistatic interaction plays an important role in controlling the expression of complex traits.

Patterns of molecular evolution and epistasis on a genomic and genic scale

Jiang, Pan-Pan
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
36.89%
Epistasis describes non-additive interactions which affect gene expression and phenotype. It can happen on multiple levels, including on a genomic level with interactions between genes or even chromosomes affecting global patterns of gene expression. It can also happen within a gene itself, with epistatic interactions between amino acids affecting gene expression and resultant phenotypes. I present three studies in two organisms to study this phenomenon on a global-genomic scale, and also on a local-genic scale.

Epistasis in an Andean x Mesoamerican cross of common bean

Fonte: Foundation Euphytica Publicador: Foundation Euphytica
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.26%
The objective of this investigation was to check if epistasis is present in Andean 9 Mesoamerican beans crosses using triple test cross (TTC) method. The parents of the segregating population were Carioca–MG (Mesoamerican) and BRS Radiante (Andean). In July 2005, F2 progenies (backcrossed with the parents and F1 generation) were evaluated at two locations for three characters: number of pods plant-1 , number of grains plant-1 and grain weight plant-1 . The presence of epistasis was detected for all yield components. In the partitioning of epistasis in additive x additive (i) and dominant x dominant (j) and dominant 9 additive (l) it was observed that, for the traits number of pods/plant and number of grains/plant, only epistasis of the type (j) ? (l) were significant. For the trait grain mass/plant, all types of epistasis were significant.

When the whole is not the sum of its parts: Testing for evidence of synergistic epistasis in Drosophila melanogaster

Mosher, Heather
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
37.33%
The prevalence of sexual reproduction despite the two-fold cost of sex is one of the most perplexing quandaries in evolutionary biology. Determining how deleterious mutations interact to reduce fitness is important because these interactions may help to explain sexual reproduction and because many population studies incorporate assumptions about genetic interactions, despite inconclusive evidence. In this study I use specially bred lines of Drosophila melanogaster to test for evidence of synergistic epistasis, the phenomenon in which deleterious mutations interact so that the negative impact of a large number of mutations is greater than would be predicted if mutations acted independently. When synergistic epistasis occurs, recombination acts to increase variance in fitness, thereby making selection more efficient at eliminating deleterious mutations. I crossed parental flies from different fitness categories and compared their fitness to the mean fitness of their recombinant offspring. If the fitness of recombinants is significantly higher or lower than the expected value based on a multiplicative relationship between mutations and fitness (calculated as the mid-parent mean), then epistasis may be occurring. My results have two major components: 1) fitness values for the parental groups are not consistent with previously measured values...

Sex and the X: An Investigation of Mutation and Epistasis on the X chromosome in Drosophila melanogaster

Pinsky, Rachael
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
37.13%
Sex is an enduring mystery in evolutionary biology. It involves a two-fold expense when compared to asexual reproduction, along with the cost of intersexual conflict. Despite these costs, most species undergo some form of sexual reproduction in each generation. There is no clear answer as to why this occurs. Some theories suggest that sex is beneficial because it increases the purging of deleterious mutations. Sexual selection may act more strongly on males, leading to a decrease in overall mutational load of a population. The mutational deterministic hypothesis suggests that synergistic epistasis between deleterious mutations decreases the fitness of individuals at a faster rate, quickly purging mutations. We tested these hypotheses using the model organism Drosophila melanogaster. We used a mutation accumulation protocol with 50 generations of a single X chromosome bottleneck. Five different X chromosomes were isolated and allowed to recombine with their controls, which are genetically identical except for the mutation accumulation protocol. This created X chromosomes with a spectrum of different mutation numbers. We created females that were either homozygous or heterozygous for their X chromosome to compensate for the difference in X chromosome number between males and females. We analyzed differences in viability between males and females...

Fitness epistasis and constraints on adaptation in a human immunodeficiency virus Type 1 protein region

Da Silva, J.; Coetzer, M.; Nedellec, R.; Pastore, C.; Mosier, D.
Fonte: Genetics Publicador: Genetics
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
37.2%
Fitness epistasis, the interaction among alleles at different loci in their effects on fitness, has potentially important consequences for adaptive evolution. We investigated fitness epistasis among amino acids of a functionally important region of the human immunodeficiency virus type 1 (HIV-1) exterior envelope glycoprotein (gp120). Seven mutations putatively involved in the adaptation of the second conserved to third variable protein region (C2–V3) to the use of an alternative host-cell chemokine coreceptor (CXCR4) for cell entry were engineered singly and in combinations on the wild-type genetic background and their effects on viral infectivity were measured. Epistasis was found to be common and complex, involving not only pairwise interactions, but also higher-order interactions. Interactions could also be surprisingly strong, changing fitness by more than 9 orders of magnitude, which is explained by some single mutations being practically lethal. A consequence of the observed epistasis is that many of the minimum-length mutational trajectories between the wild type and the mutant with highest fitness on cells expressing the alternative coreceptor are selectively inaccessible. These results may help explain the difficulty of evolving viruses that use the alternative coreceptor in culture and the delayed evolution of this phenotype in natural infection. Knowledge of common...

Positive epistasis drives the acquisition of multidrug resistance

Trindade, S.; Sousa, A.; Xavier, K.B.; Dionísio, F.; Ferreira, M.G.; Gordo, I.
Fonte: Fundação Calouste Gulbenkian Publicador: Fundação Calouste Gulbenkian
Tipo: Artigo de Revista Científica
Publicado em /07/2009 ENG
Relevância na Pesquisa
37.2%
The evolution of multiple antibiotic resistance is an increasing global problem. Resistance mutations are known to impair fitness, and the evolution of resistance to multiple drugs depends both on their costs individually and on how they interact--epistasis. Information on the level of epistasis between antibiotic resistance mutations is of key importance to understanding epistasis amongst deleterious alleles, a key theoretical question, and to improving public health measures. Here we show that in an antibiotic-free environment the cost of multiple resistance is smaller than expected, a signature of pervasive positive epistasis among alleles that confer resistance to antibiotics. Competition assays reveal that the cost of resistance to a given antibiotic is dependent on the presence of resistance alleles for other antibiotics. Surprisingly we find that a significant fraction of resistant mutations can be beneficial in certain resistant genetic backgrounds, that some double resistances entail no measurable cost, and that some allelic combinations are hotspots for rapid compensation. These results provide additional insight as to why multi-resistant bacteria are so prevalent and reveal an extra layer of complexity on epistatic patterns previously unrecognized...

Epistasis between the MHC and the RCAα block in primary Sjögren syndrome; Epistasis between the MHC and the RCA alpha block in primary Sjogren syndrome

Lester, S.; McLure, C.; Williamson, J.; Bardy, P.; Rischmueller, M.; Dawkins, R.
Fonte: British Med Journal Publ Group Publicador: British Med Journal Publ Group
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.03%
OBJECTIVE: The RCA alpha block (Regulators of Complement Activation, 1q32) contains critical complement regulatory genes such as CR1 and MCP. This study examined RCA alpha block haplotype associations with both disease susceptibility and diversification of the anti-Ro/La autoantibody response in primary Sjögren syndrome (pSS). METHODS: 115 patients with pSS and 98 controls were included in the study. 93 of 109 (85%) of the patients with pSS were seropositive for Ro/La autoantibodies. The Genomic Matching Technique (GMT) was used to define RCA alpha block ancestral haplotypes (AH). RESULTS: RCA alpha block haplotypes, AH1 and AH3, were both associated with autoantibody-positive pSS (p = 0.0003). Autoantibody associations with both HLA DR3 and DR15 have been previously defined. There was an epistatic interaction (p = 0.023) between RCA alpha AH1 and HLA DR3, and this genotypic combination was present in 48% of autoantibody-positive patients with pSS compared with 8% of controls. This epistasis is most simply attributable to an interaction between C4 and its receptor, CR1, encoded within the RCA alpha block. Both DR3 and a relative C4 deficiency are carried on the major histocompatibility complex 8.1 ancestral haplotype. Only four of 92 (4%) autoantibody-positive patients with pSS did not carry any risk RCA alpha or HLA haplotype...

Epistasis with HLA DR3 implicates the P2X7 receptor in the pathogenesis of primary Sjögren's syndrome; Epistasis with HLA DR3 implicates the P2X7 receptor in the pathogenesis of primary Sjogren's syndrome

Lester, S.; Stokes, L.; Skarratt, K.; Gu, B.; Sivils, K.; Lessard, C.; Wiley, J.; Rischmueller, M.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
37.03%
Introduction: The aim of this study was to examine the association between functional polymorphisms in the pro-inflammatory P2X7 receptor and the Ro/La autoantibody response in primary Sjögren's syndrome (pSS). Methods: Twelve functional P2RX7 polymorphisms were genotyped in 114 pSS patients fulfilling the Revised American-European Consensus Criteria for pSS, and 136 controls. Genotyping of the A1405G (rs2230912) polymorphism was performed on a replication cohort consisting of 281 pSS patients and 534 controls. P2X7 receptor function in lymphocytes and monocytes was assessed by measurement of ATP-induced ethidium+ uptake. Serum IL-18 levels were determined by ELISA. Results: The minor allele of P2RX7 A1405G is a tag for a common haplotype associated with gain in receptor function, as assessed by ATP-induced ethidium+ uptake. A positive association between 1405G and anti-Ro±La seropositive pSS patients was observed in Cohort 1. Although not replicated in Cohort 2, there was a consistent, significant, negative epistatic interaction effect with HLA-DR3 in seropositive pSS patients from both cohorts, thereby implicating this gain of function variant in the pathogenesis of pSS. Serum IL-18 was elevated in seropositive pSS patients, but was not influenced by P2RX7 A1405G. Conclusions: The P2RX7 1405G gain-of-function haplotype may be a risk factor for seropositive pSS in a subset of subjects who do not carry HLA risk alleles...

Distributions of epistasis in microbes fit predictions from a fitness landscape model

Martin, Guillaume; Elena, Santiago F.; Lenormand, Thomas
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artículo Formato: 247913 bytes; application/pdf
ENG
Relevância na Pesquisa
37.26%
6 pages, 4 figures.-- Supplementary information (Figures S1-S3, Table S1, Suppl. methods and Suppl. note) available at: http://www.nature.com/ng/journal/v39/n4/suppinfo/ng1998_S1.html; How do the fitness effects of several mutations combine? Despite its simplicity, this question is central to the understanding of multilocus evolution. Epistasis (the interaction between alleles at different loci), especially epistasis for fitness traits such as reproduction and survival, influences evolutionary predictions "almost whenever multilocus genetics matters". Yet very few models have sought to predict epistasis, and none has been empirically tested. Here we show that the distribution of epistasis can be predicted from the distribution of single mutation effects, based on a simple fitness landscape model. We show that this prediction closely matches the empirical measures of epistasis that have been obtained for Escherichia coli and the RNA virus vesicular stomatitis virus. Our results suggest that a simple fitness landscape model may be sufficient to quantitatively capture the complex nature of gene interactions. This model may offer a simple and widely applicable alternative to complex metabolic network models, in particular for making evolutionary predictions.; This work was supported by an Action Concertée Incitative from the French Ministry of Research (T.L.)...

The contribution of epistasis to the architecture of fitness in an RNA virus

Sanjuán, Rafael; Moya, Andrés; Elena, Santiago F.
Fonte: National Academy of Sciences (U.S.) Publicador: National Academy of Sciences (U.S.)
Tipo: Artículo Formato: 203 bytes; text/plain
ENG
Relevância na Pesquisa
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4 pages, 2 figures.-- PMID: 15492220 [PubMed].-- PMCID: PMC524436.-- Additional information (Suppl. table S1: Relevant information about each single- and double-nucleotide substitution mutant created) available at: http://www.pnas.org/content/101/43/15376/suppl/DC1; The tendency for genetic architectures to exhibit epistasis among mutations plays a central role in the modern synthesis of evolutionary biology and in theoretical descriptions of many evolutionary processes. Nevertheless, few studies unquestionably show whether, and how, mutations typically interact. Beneficial mutations are especially difficult to identify because of their scarcity. Consequently, epistasis among pairs of this important class of mutations has, to our knowledge, never before been explored. Interactions among genome components should be of special relevance in compacted genomes such as those of RNA viruses. To tackle these issues, we first generated 47 genotypes of vesicular stomatitis virus carrying pairs of nucleotide substitution mutations whose separated and combined deleterious effects on fitness were determined. Several pairs exhibited significant interactions for fitness, including antagonistic and synergistic epistasis. Synthetic lethals represented 50% of the latter. In a second set of experiments...

Epistasis en variedades sintéticas de maíz

Márquez Sánchez,Fidel
Fonte: Sociedad Mexicana de Fitogenética A.C. Publicador: Sociedad Mexicana de Fitogenética A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2010 ES
Relevância na Pesquisa
37.03%
En un artículo anterior se presentaron los cálculos de la epistasis para varias poblaciones de plantas de maíz (Zea mays L.) frecuentes en el mejoramiento genético, y se mostró cómo actúa este fenómeno genético de acuerdo con la estructura de las poblaciones. Dado que los maíces sintéticos poseen amplio potencial para ser aprovechados por los campesinos marginados, y dada la relativa facilidad que tienen en su obtención, en este artículo se calcula la epistasis promedio de variedades sintéticas constituidas por líneas homocigóticas bajo el modelo epistático.

Utilización del diseño TTC para detectar epistasis en soya

Acevedo Barona,Marco Antonio; Colombari Filho,José Manoel; Olivio Geraldi,Isaías
Fonte: Instituto Nacional de Investigaciones Agrícolas INIA de Venezuela Publicador: Instituto Nacional de Investigaciones Agrícolas INIA de Venezuela
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2009 ES
Relevância na Pesquisa
37.03%
El estudio de la naturaleza de la variabilidad genética existente en una población es importante, no sólo para la selección del tipo de cultivar, sino también para la escogencia del método de mejoramiento más apropiado. Con el objetivo de estudiar la variancia epistática para el carácter rendimiento en granos en soya, Glycine max L., fue utilizando el análisis "Triple Test Cross" (TTC) modificadopara especies autógamas por Jinks et al., 1969. Elmaterial experimental utilizado en este trabajo estuvo conformado por 32 líneas (Pi), escogidas aleatoriamente de una población entre los progenitores PI 123439 y PI 239235; las líneas Pi fueron posteriormente cruzadas con otras 2 líneas testadoras (L1 y L2) de la misma población, contrastantes para rendimiento en granos, las cuales fueron usadas como testadoras. Durante el ciclo 2006/2007, fueron evaluados 100 tratamientos en el arreglo experimental látice triple triplicado en parcelas experimentales de 2,00 metros de longitud, separadas 0,50 metros. Considerando la metodología del análisis biométrico, el contraste permitió detectar epistasis significativa para rendimiento en grano en soya...