Sexual dimorphism is a relevant factor in animal science, since it can affect the gene expression of economically important traits. Eventually, the interest in the prenatal phase in a transcriptome study may not comprise the period of development in which male and female conceptuses are phenotypically divergent. Therefore, it would be interesting if sex differentiation could be performed using transcriptome data, with no need for extra techniques. In this study, the sex of pig conceptuses (embryos at 25 days-old and fetuses at 35 days-old) was determined by reads counts per million (CPM) of Y chromosome-linked genes that were discrepant among samples. Thus, ten genes were used: DDX3Y, KDM5D, ZFY, EIF2S3Y, EIF1AY, LOC110255320, LOC110257894, LOC396706, LOC100625207, and LOC110255257. Conceptuses that presented reads CPM sum for these genes (ΣCPMchrY) greater than 400 were classified as males and those with ΣCPMchrY below 2 were classified as females. It was demonstrated that the sex identification can be performed at early stages of pig development from RNA-sequencing analysis of genes mapped on Y chromosome. Additionally, these results reinforce that sex determination is a mechanism conserved across mammals, highlighting the importance of using pigs as an animal model to study sex determination during human prenatal development.

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MicroRNAs are a class of naturally occurring non-coding RNAs. Typically they are $ 22 nucleotides long and suppress translation of their targets genes. Several laboratories have attempted to identify miRNAs from pig muscle and the bioinformatics strategies using ESTs have proved to be successful for this aim. In this study we report an in silico identification of ncRNA in pig EST libraries focusing on novel pig miRNAs and further investigated the differential expression of pigs miRNAs (known and novel) by quantitative real-time PCR during pre-and postnatal stage from Commercial and local breed Piau pigs skeletal muscle tissue. We identified two miRNAs not yet described in pigs: hsa-miR-1207-5p and hsa-miR-665. Besides, we found 288 target genes for hsa-miR-1207-5p and 214 for hsa-miR-665; from them, four are muscle specific genes. Through expression analyses, differences were found between pre-and postnatal stages and genetics groups. The findings of miRNAs and their muscle-specific targets in pigs will be helpful for understanding the function and processing of this RNA class in the future. Besides, the miRNAs differentially expressed between Commercial and Piau breeds suggest that they can be used to uncover phenotypic differences across different genetic groups.

In view of the importance of the genetic material of local breeds in the swine industry and the lack of information about reproductive performance of Piau females, two experiments were conducted to evaluate puberty and sexual maturity as well as the morphometry of embryos/fetuses, placenta and uterus during the first 90 days of gestation in Piau breed and Commercial line gilts. In experiment I, 37 Piau and 25 commercial line gilts were used. From the 120 days of age, detection of estrus was performed using mature boars from the first to third estrus of each gilt. Data regarding to age, body weight and estrus duration were recorded. After third estrus, females were slaughtered and ovaries were collected to determine ovulation rate. In experiment II, 36 Piau and 18 commercial line gilts were distributed into three groups according to the mating: Commercial, commercial line females x commercial line male; cross-mated, Piau females x commercial line male; and Piau, Piau females x Piau male. Gilts were slaughtered at 7, 15, 30, 45, 60 and 90 days of pregnancy. Piau females reached puberty and sexual maturity at the same age as commercial line females, but with lower weight; moreover, Piau group showed negative correlations of birth weight with puberty (-0.27) and sexual maturity (-0.29). Commercial gilts presented higher ovulation rate, weight and length of uterus, and length and thoracic circumference of fetuses. Nevertheless, number of fetuses was similar in all groups at 90 days of gestation suggesting that Piau females present higher survival rates of the conceptuses. The results showed differences between the genetic groups related to fetal and placental development, gestational losses, number of ovulations and uterine development. In addition, an intermediate status of fetal weight was observed in Piau/Commercial line crossbred conceptuses; thus, the selection of Piau females on reproductive traits to be mated with commercial line males would be an alternative to contribute to improvement of intramuscular fat content.

Dietary l‐arginine (ARG) supplementation has been studied as a nutritional strategy to improve reproductive performance of pregnant sows, since arginine is a conditionally essential amino acid. However, reports addressing the molecular mechanisms that mediate supplementation effects on embryos and fetuses development are still scarce. Therefore, we aimed to evaluate the effects of 1.0% ARG supplementation of commercial pregnant gilts on genes and proteins from energy metabolism and antioxidant defense pathways in embryos and fetuses. We also analyzed the global transcriptome profile of 25‐ and 35‐day‐old conceptuses. At Day 25, we observed a lower abundance of phospho‐AMP‐activated protein kinase (phospho‐AMPK) protein and downregulation of oxidative phosphorylation system genes in ARG embryos. On the other hand, ARG fetuses showed greater expression of MLST8 and lower expression of MTOR genes, in addition to lower abundance of phospho‐AMPK and phospho‐mammalian target of rapamycin (phospho‐mTOR) proteins. Transcriptome analysis at Day 35 did not present differentially expressed genes. For the antioxidant defense pathway, no differences were found between CON and ARG conceptuses, only trends. In general, supplementation of gilts with 1.0% ARG during early gestation affects energy sensitive pathways in 25‐ and 35‐day conceptuses; however, no effects of supplementation were found on the antioxidative defense pathway in 25‐day embryos.

Pig is an important animal for meat production; this is generally associated with characteristics determined prenatally during myogenesis. Expressed sequence tags (EST) can provide direct information on the transcriptome and indirect information on the relation between the genome and phenotype, giving information about differentially expressed genes (DEG). In this work, the identification and annotation of DEG from EST libraries of three pig breeds (Duroc, Large White and Local Breed Piau) were performed followed by real-time PCR analyses during pre- and postnatal stages (21, 40, 70 and 90 days of pregnancy and 107, 121 and 171 days postnatal) from commercial breed animals for analysis of genes expression levels. Therefore, 34 genes differentially expressed were identified, of which 21 grouped in a network related with muscle development. From this, the expression profile of 13 genes was measured, to confirm their relationship with myogenesis like ANKRD2, MYBPC1, NEB and MYL2. These genes showed a prenatal high expression in this study. Besides, novels candidates for muscle development (TP53 and DCTN1) were listed. These findings can contribute to better explaining gene function mechanism and are helpful in uncovering the pathways that mediate pre- and postnatal skeletal muscle development in vertebrates.

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