Applying an association weight matrix in weighted genomic prediction of boar taint compounds.

Biological information regarding markers and gene association may be used to attribute different weights for single nucleotide polymorphism (SNP) in genome-wide selection. Therefore, we aimed to evaluate the predictive ability and the bias of genomic prediction using models that allow SNP weighting in the genomic relationship matrix (G) building, with and without incorporating biological information to obtain the weights. Firstly, we performed a genome-wide association studies (GWAS) in data set containing single- (SL) or a multi-line (ML) pig population for androstenone, skatole and indole levels. Secondly, 1%, 2%, 5%, 10%, 30% and 50% of the markers explaining the highest proportions of the genetic variance for each trait were selected to build gene networks through the association weight matrix (AWM) approach. The number of edges in the network was computed and used to derive weights for G (AWM-WssGBLUP). The single-step GBLUP (ssGBLUP) and weighted ssGBLUP (WssGBLUP) were used as standard scenarios. All scenarios presented predictive abilities different from zero; however, the great overlap in their confidences interval suggests no differences among scenarios. Most of scenarios of based on AWM provide overestimations for skatole in both SL and ML populations. On the other hand, the skatole and indole prediction were no biased in the ssGBLUP (S1) in both SL and ML populations. Most of scenarios based on AWM provide no biased predictions for indole in both SL and ML populations. In summary, using biological information through AWM matrix and gene networks to derive weights for genomic prediction resulted in no increase in predictive ability for boar taint compounds. In addition, this approach increased the number of analyses steps. Thus, we can conclude that ssGBLUP is most appropriate for the analysis of boar taint compounds in comparison with the weighted strategies used in the present work.

Morphological and molecular differences in corpus luteum of pregnant sows from divergent genetic groups.

Comprehending mechanisms controlling corpus luteum (CL) angiogenesis and apoptosis in pregnant sows is essential to understand the physiological role of these processes in CL function, progesterone production and consequently in conceptus development and prenatal mortality. CL from 54 sows from two genetic groups, a commercial line (COM) and the local Piau breed (LPB), were obtained for gene expression (n = 3 COM; n = 6 LPB), histological and protein analysis (n = 3 COM; n = 3 LPB), divided in six gestational ages (seven, 15, 30, 45, 60 and 90 days). We observed differences between gestational ages in CL morphology, in which the average number of blood vessels/capillaries at 90-days was greater than at the seventh day by Tukey test. RT-qPCR analysis revealed that apoptotic genes (BAX, BCL2 and CASP3) were differentially expressed between genetic groups and gestational ages in each group. Angiogenesis genes also presented differences between genetic groups (ANGPT1) and gestational ages (MMP9, VEGFA and ANGPT1). No differences in protein abundance of steroidogenic enzymes (CYP11A1 and HSD3B1) were observed. Our findings indicate that despite the differences in gene expression, differences in corpus luteum vascularization were observed only across gestational ages, with no dissimilarities between genetic groups.