Gene de efeito associativo na detecção de major genes

• Ano de defesa: 2009
• Autor(a) principal: Schierholt, Alex Sandro
• Orientador(a): Euclydes, Ricardo Frederico
• Banca de defesa: Pires, Aldrin Vieira , Carneiro, Paulo Luiz Souza , Braccini Neto, José
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Simulação; Parâmetros genéticos; Efeitos associativos
• Palavras-chave em Inglês: Simulation; Genetic parameters; Associative effect
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS
• Link de acesso: http://locus.ufv.br/handle/123456789/1728

The Associative effects are produced by the influence that social environment has on gene expression in group companion animals. This social environment is defined in part by genes responsible for the behavior of the animals composing the group, called associative genes. These genes may be diminishing the power detection of major genes with direct effects, or even being identified as if they were genes with direct effects. This work was made aiming the evaluation of the influence of associative genes in identification analyses of major genes. The data were generated by simulation. A genome of 2471 cM, the allele frequencies and effects of 200 QTL (quantitative trait loci) were simulated. Two of these QTL were transformed in major genes, one with direct effects over the individual phenotype, the direct major gene, and another with associative effects over the phenotype of group companions, the associative major gene. The population in study was made by selecting randomly 3740 simulated animals, offspring of 20 males and 337 females, forming 11 group classes with 10 animals in each group and setting 34 repetitions for each class. The classes were determined by the number of animals with the dominant allele for the associative gene in each group, varying from zero to 10 individuals B_. The associative major gene was simulated acting in two ways: influencing the predisposition of the animal to be involved in disputes for a better position in the hierarchy, the pre-hierarchical associative effect, having effect promoted by the aggressiveness among the animals; and another, the post-hierarchical effect, promoted by the benefits that animals in a higher hierarchical position have for having differentiated access to the resources. Two major sets of simulations were performed, using the same simulated population, one considering the associative gene with pre and post- hierarchical effects and another considering the associative gene only with post-hierarchical effects. Within these two major sets of simulations, three levels of effects for the direct major gene were considered (adding 1%, 3% and 5% of the population phenotype mean to the phenotype of the animals). The associative major gene effect was simulated considering only one level of effect for the pre-hierarchical effect (each aggressive animal B_ caused a decrease of 8% in the expression of the direct major gene at group companions) and four level of effects for the post-hierarchical effect (each B_ animal caused a decrease of 5%, 10%, 20% and 30% in the expression of the direct major gene at group companions). In order to verify the influence of associative genes in analyses of major gene detection, both major genes were evaluated as direct major genes, by mean test, in an attempt to identify major genes with direct effect in the phenotype of animals. The results showed that, for the genes effect levels simulated, the associative effect could not mask the identification of major genes with direct effect (p < 0,01). The analysis testing whether the associative major gene would be identified as a gene with direct effect showed that, in simulations with direct effect gene levels contributing with more than 3% of the phenotypic mean of the population, the associative major gene was identified as a major gene of direct effect (p < 0,01).