Les causes genètiques dels efectes de l'endogàmia, a estudi

L'endogàmia, o aparellament entre individus emparentats, porta associats uns efectes, sobretot si es perllonga durant generacions, com la pèrdua d'aptitud biològica o fitness. És l'anomenada depressió endogàmica. Investigadors de la UAB han fet un estudi de les bases genètiques d'aquests efectes en una població endogàmica de conills i han trobat que la complexitat de la genètica associada a la depressió endogàmica és caracteritzada per la presència d'interaccions entre gens (o epistasi) i que, tot i tenir generalment conseqüències negatives, no es poden descartar efectes positius.La endogamia, o apareamiento entre individuos emparentados, lleva asociados unos efectos, sobre todo si se prolonga durante generaciones, como la pérdida de aptitud biológica o fitness. Es la llamada depresión endogámica. Investigadores de la UAB han hecho un estudio de las bases genéticas de estos efectos en una población endogámica de conejos y han encontrado que la complejidad de la genética asociada a la depresión endogámica está caracterizada por la presencia de interacciones entre genes (o epistasia) y que, a pesar de tener generalmente consecuencias negativas, no se pueden descartar efectos positivos

Primer pas per reduir el temps entre part i part en ovelles de raça Ripollesa

Les ovelles de la raça Ripollesa són criades sobretot per a l'obtenció de carn, destacant els seus xais lletons, xais de poques setmanes que han begut llet d'ovella i que produeixen una carn molt tendre i de gran qualitat. Per aquesta raó, en aquesta raça, és important establir el temps que passa entre dos parts successius d'una mateixa ovella. Una reducció d'aquest temps mitjançant selecció genètica incrementaria el rendiment econòmic dels ramats d'ovelles de raça Ripollesa. Una recerca realitzada per un equip del Departament de Ciència Animal i dels Aliments de la UAB ha mostrat estadísticament la possibilitat d'incloure la reducció de l'interval de temps entre part i part en els programes de millora genètica que fins ara no l'incloïen degut a què es pensava que era un caràcter poc heretable.Las ovejas de la raza Ripollesa son criadas sobre todo para la obtención de carne, destacando sus "xais lletons", corderos de pocas semanas que han bebido leche de oveja y que producen una carne muy tierna y de gran calidad. Por esta razón, en esta raza, es importante establecer el tiempo que pasa entre dos partos sucesivos de una misma oveja. Una reducción de este tiempo mediante selección genética incrementaría el rendimiento económico de los rebaños de ovejas de raza Ripollesa. Una investigación realizada por un equipo del Departamento de Ciencia Animal y de los Alimentos de la UAB ha mostrado estadísticamente la posibilidad de incluir la reducción del intervalo de tiempo entre parto y parto en los programas de mejora genética, que hasta ahora no lo incluían pensado que era un carácter poco hereditario

Posibilidades del sistema "Starfish" para el diseño de tejidos de malla de algodón.

Se describen los orígenes, metodología y posibilidades de utilización de las bases de datos del "Starfish System" desarrollado por el Instituto Internacional del Algodón para la predicción fiable de las propiedades dimensionales de los tejidos de punto de algodón una vez sometidos a los tratamientos de acabado, lo que permite, a partir de las características de los hilos a emplear, estructura del tejidos y maquinaria para la fabricación y acabado, establecer las condiciones de trabajo adecuadas para obtener unas dimensiones estables prefijadas. EL INSTITUTO DE INVESTIGACIÓN TEXTIL Y COOPERACIÓN INDUSTRIAL DE TERRASSA ha adquirido los derechos de explotación del mismo, ofreciendo a la industria de ese sector, la posibilidad de su utilización.Peer Reviewe

Between-groups within-gene heterogeneity of residual variances in microarray gene expression data

<p>Abstract</p> <p>Background</p> <p>The analysis of microarray gene expression data typically tries to identify differential gene expression patterns in terms of differences of the mathematical expectation between groups of arrays (e.g. treatments or biological conditions). Nevertheless, the differential expression pattern could also be characterized by group-specific dispersion patterns, although little is known about this phenomenon in microarray data. Commonly, a homogeneous gene-specific residual variance is assumed in hierarchical mixed models for gene expression data, although it could result in substantial biases if this assumption is not true.</p> <p>Results</p> <p>In this manuscript, a hierarchical mixed model with within-gene heterogeneous residual variances is proposed to analyze gene expression data from non-competitive hybridized microarrays. Moreover, a straightforward Bayes factor is adapted to easily check within-gene (between groups) heterogeneity of residual variances when samples are grouped in two different treatments. This Bayes factor only requires the analysis of the complex model (hierarchical mixed model with between-groups heterogeneous residual variances for all analyzed genes) and gene-specific Bayes factors are provided from the output of a simple Markov chain Monte Carlo sampling.</p> <p>Conclusion</p> <p>This statistical development opens new research possibilities within the gene expression framework, where heterogeneity in residual variability could be viewed as an alternative and plausible characterization of differential expression patterns.</p

Freemartinism in replacement ewe-lambs of the Ripollesa sheep breed

The freemartinism syndrome affects almost all female calves born as co-twins to male calves, whereas little is known about this phenomenon in female sheep. Within this context, 1,185 ewe-lambs from the Ripollesa sheep breed were genotyped for the presence of oY1 polymorphism (a non-autosomal region of the Y chromosome). Neither ewe-lambs from single births (856) nor ewe-lambs from all-female multiple births (170) were revealed as freemartins, whereas five of 159 ewe-lambs from multiple births with male co-twins were freemartins (3.15 ± 1.38%). All freemartin ewe-lambs were confirmed by physical examination of external genitalia. The results confirm a low incidence of freemartinism from heterosexual twin pregnancies in Ripollesa sheep

Estado del arte en la ignifugación de tejidos.

Se realiza una reflexión sobre el estado actual de la técnica en el acabado ignifugo de tejidos, no tan sólo desde la perspectiva de la inflamabilidad, sino desde el concepto global de "Comportamiento al Fuego", que engloba tanto la reacción al fuego y frente a las diversas formas de propagación del calor, como la cuantificación de la adversidad de las atmósferas de combustión, exponiéndose una valoración objetiva de la eficacia de los productos comerciales que están a disposición del técnico acabador, en base a resultados que resumen estudios realizados por los autores, en los últimos años.A revision of the present situation of the techniques used in the finishing of fire-proof fabrics is made. The behaviour with the fire - including the reaction fire and the various forms of the heat propagation - and the quantification of the adversity of the combustion atmospheres is considered. An objective assesment of the efficiency of the commercial products available in the market is given; this evaluation is based on the results of a long experience of the authors on this matter.On réalise une réflexion sur l'état actual de la technique dans le finissage igniguge de tissus, non seulement de la perspective de l'inflammabilité, mais aussi à partir du concept global de Comportement au Feu, qui comprend la réaction au feu et aussi face aux diverses formes de propagation de la chaleur, aussi bien que la mesure de l'adversité des atmosphères de combustion; on expose une évaluation objective de l'efficacité des produits commercials qui sont à la disposition du technicien finisseur, en base à des résultats qui résument des études realisées par l'auteaur, et ses collaborateurs, dans les dernières années.Peer Reviewe

Bayes factors for testing between different structures of random genetic groups : a case study using weanin weight in Bruna dels Pirineus beef cattle

The implementation of genetic groups in BLUP evaluations accounts for different expectations of breeding values in base animals. Notwithstanding, many feasible structures of genetic groups exist and there are no analytical tools described to compare them easily. In this sense, the recent development of a simple and stable procedure to calculate the Bayes factor between nested competing models allowed us to develop a new approach of that method focused on compared models with different structures of random genetic groups. The procedure is based on a reparameterization of the model in terms of intraclass correlation of genetic groups. The Bayes factor can be easily calculated from the output of a Markov chain Monte Carlo sampling by averaging conditional densities at the null intraclass correlation. It compares two nested models, a model with a given structure of genetic groups against a model without genetic groups. The calculation of the Bayes factor between different structures of genetic groups can be quickly and easily obtained from the Bayes factor between the nested models. We applied this approach to a weaning weight data set of the Bruna dels Pirineus beef cattle, comparing several structures of genetic groups, and the final results showed that the preferable structure was an only group for unknown dams and different groups for unknown sires for each year of calving

SNP+ to predict dropout rates in SNP arrays

Altres ajuts: acords transformatius de la UAB. Altres ajuts: LoupO project (EFA354/19) of the European Interreg Program V-A Spain-France-Andorra (POCTEFA 2014-2020)Genotyping individuals using forensic or non-invasive samples such as hair or fecal samples increases the risk of allelic amplification failure (dropout) due to the low quality and quantity of DNA. One way to decrease genotyping errors is to increase the number of replicates per sample. Here, we have developed the software SNP+ to estimate the dropout probability and the subsequent required number of replicates to obtain the reliable genotype with probability 95%. Moreover, the software predicts the minor allele frequency and compares two competing models assuming equal or allele-specific dropout probabilities by Bayes factor. The software handles data from one SNP to high density arrays (e.g., 100,000 SNPs)

Low-coverage whole-genome sequencing in livestock species for individual traceability and parentage testing

Altres ajuts: Acord transformatiu CRUE-CSICProcedures for genetic traceability of animal products and parentage testing mainly focus on microsatellites or SNPs panels. Nevertheless, current availability of high-throughput sequencing technologies must be considered as an appealing alternative. This research focused on the evaluation of low-coverage whole-genome sequencing for traceability and paternity testing purposes, within a context of evidential statistics. Analyses were performed on a simulation basis and assumed individuals with 30 100-Mb/100-cM chromosome pairs and ~1,000,000 polymorphic SNPs per chromosome. Ten independent populations were simulated under recombination and mutation with effective populations size 100 (generations 1-1000), 10,000 (generation 1001) and 25,000 (generation 1002), and this last generation was retained for analytical purposes. Appropriate both traceability and paternity tests were developed and evaluated on different high-throughput sequencing scenarios accounting for genome coverage depth (0.01×, 0.05×, 0.1× and 0.5×), length of base-pair reads (100, 1000 and 10,000 bp), and sequencing error rate (0%, 1% and 10%). Assuming true sequencing error rates and genotypic frequencies, 0.05× genome coverage depth guaranteed 100% sensitivity and specificity for traceability and paternity tests (n = 1000). Same results were obtained when sequencing error rate was arbitrarily set to 0, or the maximum value assumed during simulation (i.e., 1%). In a similar way, uncertainly about genotypic frecuencies did not impair sensitivity under 0.05× genome coverage, although it reduced specificity for paternity tests up to 85.2%. These results highlighted low-coverage whole-genome sequencing as a promising tool for the livestock and food industry with both technological and (maybe) economic advantages

Evidential segregation analysis for offspring sex ratio in rabbit and sheep populations

Altres ajuts: acords transformatius de la UABOffspring sex ratio has been found to be altered by environmental and genetic distortions in multiple species, against the Mendelian inheritance rules. However, little is known in livestock populations where it is essential to validate whether a polymorphic major gene with relevant effects may segregate in the target population. However, the current analytical tool (model FREQ) cannot handle new mutations in non-founder individuals, reducing the chance of detecting them. Our new analytical approach aimed to overcome this limitation in the context of evidential inference, a statistical framework based on the likelihood function as a robust objective measure of the strength of statistical evidence without variation from the sample size. Two field data sets from sheep and rabbit populations were used. Models evaluated environmental and inbreeding effects in both species. Our new approach assumed that the mutation primarily arose in an individual of the analyzed data set (model MUTj). Each sire was individually analyzed to determine the most plausible source for the new mutation, if any. The likelihood ratio (LR) against a reference parametrization without mutations (model NULL) was used to test the statistical relevance of systematic effects (LR ≥ 8) and models (LR ≥ 32). Both species revealed relevant departures for offspring sex ratio along the analyzed time frame with strong evidence for the year (LR = 1.4 × 10 in Ripollesa sheep and LR = 85.7 in MARET rabbits) and season (LR = 12.6 in MARET rabbits), although with a fluctuating pattern. The age of the dam reported weak evidence in both species (LR 32) was the Ripollesa sheep, with a ram three to six generations from the founders as the most likely source for a new mutation increasing the odds of daughters. The additive genetic effect of this model for the mutant allele also had strong evidence (LR = 1,195). Therefore, the MUT parametrization can be a valuable analytical tool to check for the possibility of new mutations along the pedigree files, not only before the founders