Effects of environmental and physiological covariates on sex differences in unconditioned and conditioned anxiety and fear in a large sample of genetically heterogeneous (N/Nih-HS) rats

Physiological and environmental variables, or covariates, can account for an important portion of the variability observed in behavioural/physiological results from different laboratories even when using the same type of animals and phenotyping procedures. We present the results of a behavioural study with a sample of 1456 genetically heterogeneous N/Nih-HS rats, including males and females, which are part of a larger genome-wide fine-mapping QTL (Quantitative Trait Loci) study. N/Nih-HS rats have been derived from 8 inbred strains and provide very small distance between genetic recombinations, which makes them a unique tool for fine-mapping QTL studies. The behavioural test battery comprised the elevated zero-maze test for anxiety, novel-cage (open-field like) activity, two-way active avoidance acquisition (related to conditioned anxiety) and context-conditioned freezing (i.e. classically conditioned fear). Using factorial analyses of variance (ANOVAs) we aimed to analyse sex differences in anxiety and fear in this N/Nih-HS rat sample, as well as to assess the effects of (and interactions with) other independent factors, such as batch, season, coat colour and experimenter. Body weight was taken as a quantitative covariate and analysed by covariance analysis (ANCOVA). Obliquely-rotated factor analyses were also performed separately for each sex, in order to evaluate associations among the most relevant variables from each behavioural test and the common dimensions (i.e. factors) underlying the different behavioural responses. ANOVA analyses showed a consistent pattern of sex effects, with females showing less signs of anxiety and fear than males across all tests. There were also significant main effects of batch, season, colour and experimenter on almost all behavioural variables, as well as "sex × batch", "sex × season" and "sex × experimenter" interactions. Body weight showed significant effects in the ANCOVAs of most behavioural measures, but sex effects were still present in spite of (and after controlling for) these "body weight" effects. Factor analyses of relevant variables from each test showed a two-fold factor structure in both sexes, with the first factor mainly representing anxiety and conditioned fear in males, while in females the first factor was dominated by loadings of activity measures. Thus, besides showing consistent sex differences in anxiety-, fear- and activity-related responses in N/Nih-HS rats, the present study shows that females' behaviour is predominantly influenced by activity while males are more influenced by anxiety. Moreover, the results point out that, besides "sex" effects, physiological variables such as colour and body weight, and environmental factors as batch/season or "experimenter", have to be taken into account in both behavioural and quantitative genetic studies because of their demonstrated influences on phenotypic outcomes

Fine mapping of bone structure and strength QTLs in heterogeneous stock rat

We previously demonstrated that skeletal structure and strength phenotypes vary considerably in heterogeneous stock (HS) rats. These phenotypes were found to be strongly heritable, suggesting that the HS rat model represents a unique genetic resource for dissecting the complex genetic etiology underlying bone fragility. The purpose of this study was to identify and localize genes associated with bone structure and strength phenotypes using 1524 adult male and female HS rats between 17 to 20 weeks of age. Structure measures included femur length, neck width, head width; femur and lumbar spine (L3-5) areas obtained by DXA; and cross-sectional areas (CSA) at the midshaft, distal femur and femoral neck, and the 5th lumbar vertebra measured by CT. In addition, measures of strength of the whole femur and femoral neck were obtained. Approximately 70,000 polymorphic SNPs distributed throughout the rat genome were selected for genotyping, with a mean linkage disequilibrium coefficient between neighboring SNPs of 0.95. Haplotypes were estimated across the entire genome for each rat using a multipoint haplotype reconstruction method, which calculates the probability of descent at each locus from each of the 8 HS founder strains. The haplotypes were then tested for association with each structure and strength phenotype via a mixed model with covariate adjustment. We identified quantitative trait loci (QTLs) for structure phenotypes on chromosomes 3, 8, 10, 12, 17 and 20, and QTLs for strength phenotypes on chromosomes 5, 10 and 11 that met a conservative genome-wide empiric significance threshold (FDR=5%; P<3×10(-6)). Importantly, most QTLs were localized to very narrow genomic regions (as small as 0.3 Mb and up to 3 Mb), each harboring a small set of candidate genes, both novel and previously shown to have roles in skeletal development and homeostasis

Aplicabilidad del análisis de microarray en la detección de patrones de expresión genética diferencial en procesos psicológicos: expresión genética amigdalar en ratas N/Nih-HS extremas en ansiedad.

En el presente trabajo, se revisan las principales investigaciones sobre las bases gen&eacute;ticas del miedo, los trastornos de ansiedad y depresivos, as&iacute; como de la susceptibilidad a las drogas, que han utilizado la t&eacute;cnica de microarray. Finalmente se presenta un resumen de algunos resultados preliminares, obtenidos por nuestro grupo de investigaci&oacute;n, en el an&aacute;lisis de la expresi&oacute;n g&eacute;nica diferencial en ratas gen&eacute;ticamente heterog&eacute;neas (N/Nih-HS) seleccionadas por su alta/baja ansiedad, en funci&oacute;n de su capacidad para la adquisici&oacute;n de la tarea de evitaci&oacute;n activa en dos sentidos (en la Shuttle-box)

Genetic studies of emotional behaviour in rats

Aquest treball doctoral explora dues aproximacions a l’estudi de la conducta a través de la genètica. La primera és una aproximació de caire intervencionista l'objectiu de la qual és estudiar la funció conductual de la regió del Cornus Ammonis (CA) a l’hipocamp utilitzant un model transgènic. La tesi descriu els processos per a validar aquesta aproximació mitjançant un model d’ablació cel.lular induïda per la toxina diftèrica, i els nostres resultats demostren la inserció del constructe i una expressió parcial. Describim els resultats tot analitzant la viabilitat d’aquest model per a l’estudi de la conducta. La segona aproximació és un estudi observacional de l’heretabilitat dels trets complexos com el comportament ansiós mitjançant l’anàlisi de dades genotípiques i fenotípiques. Analitzant una llarga mostra de rates heterogènies describim com l’heretabilitat dels trets complexos té un efecte lligat al parent d’origen (parent-of-origin effect) en rates, i centrem l’anàlisi en les conductes i estratègies d’enfrontament davant d’estímuls estressants (coping style).The present work explores two approaches to the study of behaviour through genetics. The first approach is an interventional transgenic model that aims to study the behavioral function of the Cornus Ammonis (CA) sub region in the hippocampus. I describe the steps to validate an interventional model using a diphtheria-induced cell knockout rat, and our results confirm the insertion of the transgenic construct and a partial expression. We report the results and discuss the feasibility of the model. The second approach is an observational study of the heritability of complex traits such as anxious behaviour analysing phenotypic and genotypic data. Using a large sample of outbred heterogeneous stock rats, I describe how the heritability of complex traits has a parent-of-origin effect in rats, and focus the analysis on coping style behaviour

Genetic studies of emotional behaviour in rats

Aquest treball doctoral explora dues aproximacions a l'estudi de la conducta a través de la genètica. La primera és una aproximació de caire intervencionista l'objectiu de la qual és estudiar la funció conductual de la regió del Cornus Ammonis (CA) a l'hipocamp utilitzant un model transgènic. La tesi descriu els processos per a validar aquesta aproximació mitjançant un model d'ablació cel·lular induïda per la toxina diftèrica, i els nostres resultats demostren la inserció del constructe i una expressió parcial. Describim els resultats tot analitzant la viabilitat d'aquest model per a l'estudi de la conducta. La segona aproximació és un estudi observacional de l'heretabilitat dels trets complexos com el comportament ansiós mitjançant l'anàlisi de dades genotípiques i fenotípiques. Analitzant una llarga mostra de rates heterogènies describim com l'heretabilitat dels trets complexos té un efecte lligat al parent d'origen (parent-of-origin effect) en rates, i centrem l'anàlisi en les conductes i estratègies d'enfrontament davant d'estímuls estressants (coping style).The present work explores two approaches to the study of behaviour through genetics. The first approach is an interventional transgenic model that aims to study the behavioral function of the Cornus Ammonis (CA) sub region in the hippocampus. I describe the steps to validate an interventional model using a diphtheria-induced cell knockout rat, and our results confirm the insertion of the transgenic construct and a partial expression. We report the results and discuss the feasibility of the model. The second approach is an observational study of the heritability of complex traits such as anxious behaviour analysing phenotypic and genotypic data. Using a large sample of outbred heterogeneous stock rats, I describe how the heritability of complex traits has a parent-of-origin effect in rats, and focus the analysis on coping style behaviour

What can we learn on rodent fearfulness/anxiety from the genetically heterogeneous NIH-HS rat stock?

The m(7)G caps of most spliceosomal snRNAs and certain snoRNAs are converted posttranscriptionally to 2,2,7-trimethylguanosine (m(3)G) cap structures. Here, we show that yeast Tgs1p, an evolutionarily conserved protein carrying a signature of S-AdoMet methyltransferase, is essential for hypermethylation of the m(7)G caps of both snRNAs and snoRNAs. Deletion of the yeast TGS1 gene abolishes the conversion of the m(7)G to m(3)G caps and produces a cold-sensitive splicing defect that correlates with the retention of U1 snRNA in the nucleolus. Consistently, Tgs1p is also localized in the nucleolus. Our results suggest a trafficking pathway in which yeast snRNAs and snoRNAs cycle through the nucleolus to undergo m(7)G cap hypermethylation

Combined sequence-based and genetic mapping analysis of complex traits in outbred rats

<p>Genetic mapping on fully sequenced individuals is transforming understanding of the relationship between molecular variation and variation in complex traits. Here we report a combined sequence and genetic mapping analysis in outbred rats that maps 355 quantitative trait loci for 122 phenotypes. We identify 35 causal genes involved in 31 phenotypes, implicating new genes in models of anxiety, heart disease and multiple sclerosis. The relationship between sequence and genetic variation is unexpectedly complex: at approximately 40% of quantitative trait loci, a single sequence variant cannot account for the phenotypic effect. Using comparable sequence and mapping data from mice, we show that the extent and spatial pattern of variation in inbred rats differ substantially from those of inbred mice and that the genetic variants in orthologous genes rarely contribute to the same phenotype in both species.</p>

Homomorphisms and Ramsey properties of antimatroids

SIGLEBibliothek Weltwirtschaft Kiel C132,202 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman