Bidirectional genetic selection of behaviors involved in social interaction of Wistar rats

Bidirectional selection is a procedure in which an arbitrary characteristic is chosen as a selection criterion and animals exhibiting more of this characteristic are bred in one group and animals exhibiting less are bred in another group. The procedure is repeated along generations until the selected characteristic becomes stable, resulting in two strains that are opposite in relation to the chosen characteristic. The present study aimed at selectively breeding rats exhibiting either a high or a low tendency to socialize by using the proximity test. We tested male and female Wistar rats in a square open field with a communicating birdcage, separated by a grid, containing a co-specific rat and coupled on the outside. Subjects that remained more time in front of the birdcage, interacting with the co-specific rat were bred in a group considered of high sociability (SOC+). Likewise, subjects that remained little time in front of the birdcage, with little interaction with the co-specific rat, were bred in a second group considered of low sociability (SOC-). By the 10th generation, the bidirectional selection resulted in SOC+ rats that spent a large amount of time in front of the cage sniffing and rearing in interaction with the co-specific rat and spent less time in the corners, exploring and grooming. It also resulted in SOC- rats that spent a small amount of time in front of the cage sniffing and rearing in interaction with the co-specific rat and spent more time in the corners and used most of their time grooming.

Soybean productivity, stability, and adaptability through mixed model methodology / Produtividade, estabilidade e adaptabilidade da soja por meio de metodologia de modelo misto

ABSTRACT: The genotype × environment (G×E) interaction plays an essential role in phenotypic expression and can lead to difficulties in genetic selection. Thus, the present study aimed to estimate genetic parameters and to compare different selection strategies in the context of mixed models for soybean breeding. For this, data referring to the evaluation of 30 genotypes in 10 environments, regarding the grain yield trait, were used. The variance components were estimated through restricted maximum likelihood (REML) and genotypic values were predicted through best linear unbiased prediction (BLUP). Significant effects of genotypes and G×E interaction were detected by the likelihood ratio test (LRT). Low genotypic correlation was obtained across environments, indicating complex G×E interaction. The selective accuracy was very high, indicating high reliability. Our results showed that the most productive soybean genotypes have high adaptability and stability.

RESUMO: A interação genótipo × ambiente (G × E) desempenha um papel essencial na expressão fenotípica e pode provocar dificuldades na seleção genética. Assim, o presente estudo teve como objetivo estimar parâmetros genéticos e comparar diferentes estratégias de seleção no contexto de modelos mistos para melhoramento da soja. Para isso, foram utilizados dados referentes à avaliação de 30 genótipos em dez ambientes, referentes à característica produtividade de grãos. Os componentes de variância foram estimados pela máxima verossimilhança restrita (REML) e os valores genotípicos foram preditos pela melhor previsão imparcial linear (BLUP). Efeitos significativos dos genótipos e interação G × E foram detectados pelo teste da razão de verossimilhança (LRT). Correlação genotípica baixa foi obtida entre os ambientes indicando interação G × E do tipo complexa. A acurácia seletiva foi muito alta, indicando alta confiabilidade. Os resultados mostraram que os genótipos de soja mais produtivos apresentam alta adaptabilidade e estabilidade.

Fundamentos ontológicos do debate sobre seleção e edição do genoma / Ontological fundamentals of the debate on genetic selection and gene editing

Este trabalho problematiza os pressupostos ontológicos assumidos no debate bioético sobre a seleção e edição do genoma humano. Com vistas ao manejo de desordens genéticas, diferentes terapêuticas têm sido empregadas clínica e experimentalmente, desde a década de 1990. Entre as estratégias de tratamento destacam-se a seleção de embriões (mediante diagnóstico genético pré-implantação) e a terapia gênica (mediante edição genética). O desenvolvimento destas técnicas suscita discussões acerca de suas implicações éticas. O presente artigo postula que distintas concepções de humanidade podem ser identificadas nas discussões, as quais fundamentam posicionamentos acerca de intervenções sobre o genoma da espécie. O artigo busca analisar essas concepções, percorrendo três passos. Primeiramente, apresenta-se o contexto biomédico de aplicação da seleção e edição do genoma humano. Em seguida, são evidenciadas discussões sobre os aspectos éticos de tais intervenções. Por fim, explicitam-se diferentes concepções de humanidade que fundamentam as referidas discussões, de maneira a problematizá-las, tendo em vista a noção de justiça distributiva.(AU)

This study discusses the ontological assumptions assumed in the bioethical debate about human genetic selection and gene editing. With a view to managing genetic disorders, different therapies have been employed clinically and experimentally, since the 1990s. Among the treatment strategies, we find embryo selection (by means of pre-implantation genetic diagnosis) and gene therapy (by means of gene editing). The development of these techniques raises discussions about their ethical implications. This article postulates that different conceptions of humanity can be identified in these discussions, grounding ethical positions regarding genome interventions. The article seeks to analyze these conceptions, following three steps. First, the biomedical context of genetic selection and gene editing is presented. Then, discussions on the ethical aspects of these interventions are highlighted. Finally, different conceptions of humanity grounding these discussions are identified and analyzed, considering the notion of distributive justice.(AU)

Multiple Group Testing Procedures for Analysis of High-Dimensional Genomic Data

In genetic association studies with high-dimensional genomic data, multiple group testing procedures are often required in order to identify disease/trait-related genes or genetic regions, where multiple genetic sites or variants are located within the same gene or genetic region. However, statistical testing procedures based on an individual test suffer from multiple testing issues such as the control of family-wise error rate and dependent tests. Moreover, detecting only a few of genes associated with a phenotype outcome among tens of thousands of genes is of main interest in genetic association studies. In this reason regularization procedures, where a phenotype outcome regresses on all genomic markers and then regression coefficients are estimated based on a penalized likelihood, have been considered as a good alternative approach to analysis of high-dimensional genomic data. But, selection performance of regularization procedures has been rarely compared with that of statistical group testing procedures. In this article, we performed extensive simulation studies where commonly used group testing procedures such as principal component analysis, Hotelling's T² test, and permutation test are compared with group lasso (least absolute selection and shrinkage operator) in terms of true positive selection. Also, we applied all methods considered in simulation studies to identify genes associated with ovarian cancer from over 20,000 genetic sites generated from Illumina Infinium HumanMethylation27K Beadchip. We found a big discrepancy of selected genes between multiple group testing procedures and group lasso.