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Iberian pig production includes purebred (IB) and Duroc-crossbred (IBxDU) pigs, which show important differences in growth, fattening and tissue composition. This experiment was conducted to investigate the effects of genetic type and muscle (Longissimus dorsi (LD) vs Biceps femoris (BF)) on gene expression and transcriptional regulation at two developmental stages. Nine IB and 10 IBxDU piglets were slaughtered at birth, and seven IB and 10 IBxDU at four months of age (growing period). Carcass traits and LD intramuscular fat (IMF) content were measured. Muscle transcriptome was analyzed on LD samples with RNA-Seq technology. Carcasses were smaller in IB than in IBxDU neonates (p < 0.001), while growing IB pigs showed greater IMF content (p < 0.05). Gene expression was affected (p < 0.01 and Fold change > 1.5) by the developmental stage (5,812 genes), muscle type (135 genes), and genetic type (261 genes at birth and 113 at growth). Newborns transcriptome reflected a highly proliferative developmental stage, while older pigs showed upregulation of catabolic and muscle functioning processes. Regarding the genetic type effect, IBxDU newborns showed enrichment of gene pathways involved in muscle growth, in agreement with the higher prenatal growth observed in these pigs. However, IB growing pigs showed enrichment of pathways involved in protein deposition and cellular growth, supporting the compensatory gain experienced by IB pigs during this period. Moreover, newborn and growing IB pigs showed more active glucose and lipid metabolism than IBxDU pigs. Moreover, LD muscle seems to have more active muscular and cell growth, while BF points towards lipid metabolism and fat deposition. Several regulators controlling transcriptome changes in both genotypes were identified across muscles and ages (SIM1, PVALB, MEFs, TCF7L2 or FOXO1), being strong candidate genes to drive expression and thus, phenotypic differences between IB and IBxDU pigs. Many of the identified regulators were known to be involved in muscle and adipose tissues development, but others not previously associated with pig muscle growth were also identified, as PVALB, KLF1 or IRF2. The present study discloses potential molecular mechanisms underlying phenotypic differences observed between IB and IBxDU pigs and highlights candidate genes implicated in these molecular mechanisms.

Iberian ham production includes both purebred (IB) and Duroc-crossbred (IBxDU) Iberian pigs, which show important differences in meat quality and production traits, such as muscle growth and fatness. This experiment was conducted to investigate gene expression differences, transcriptional regulation and genetic polymorphisms that could be associated with the observed phenotypic differences between IB and IBxDU pigs. Nine IB and 10 IBxDU pigs were slaughtered at birth. Morphometric measures and blood samples were obtained and samples from Biceps femoris muscle were employed for compositional and transcriptome analysis by RNA-Seq technology. Phenotypic differences were evident at this early age, including greater body size and weight in IBxDU and greater Biceps femoris intramuscular fat and plasma cholesterol content in IB newborns. We detected 149 differentially expressed genes between IB and IBxDU neonates (p < 0.01 and Fold-Change > 1. 5). Several were related to adipose and muscle tissues development (DLK1, FGF21 or UBC). The functional interpretation of the transcriptomic differences revealed enrichment of functions and pathways related to lipid metabolism in IB and to cellular and muscle growth in IBxDU pigs. Protein catabolism, cholesterol biosynthesis and immune system were functions enriched in both genotypes. We identified transcription factors potentially affecting the observed gene expression differences. Some of them have known functions on adipogenesis (CEBPA, EGRs), lipid metabolism (PPARGC1B) and myogenesis (FOXOs, MEF2D, MYOD1), which suggest a key role in the meat quality differences existing between IB and IBxDU hams. We also identified several polymorphisms showing differential segregation between IB and IBxDU pigs. Among them, non-synonymous variants were detected in several transcription factors as PPARGC1B and TRIM63 genes, which could be associated to altered gene function. Taken together, these results provide information about candidate genes, metabolic pathways and genetic polymorphisms potentially involved in phenotypic differences between IB and IBxDU pigs associated to meat quality and production traits.

Antioxidant supplementation in critical periods may be useful for improvement of piglet early viability and development. We have evaluated the effects of maternal perinatal diet inclusion of a high vitamin E level (VE, 100 mg all-rac-α-tocopheryl acetate /kg), hydroxytyrosol (HT, 1.5 mg/kg), or their combination (VEHT), in comparison to a control diet (C, 30 mg all-rac-α-tocopheryl acetate /kg), on the offspring homeostasis and metabolism, analysing the weaned piglets' adipose tissue transcriptome and adipocyte morphology. Diets were provided to pregnant Iberian sows (n = 48, 12 per treatment) from gestation day 85 to weaning (28 days postpartum) and 48 piglets (n = 12 per treatment) were sampled 5 days postweaning for dorsal subcutaneous adipose tissue analyses. RNA obtained from 6 animals for each diet was used for paired-end RNA sequencing. Results show that supplementation of sows' diet with either vitamin E or hydroxytyrosol had substantial effects on weaned piglet adipose transcriptome, with 664 and 587 genes being differentially expressed, in comparison to C, respectively (q-value<0.10, Fold Change>1.5). Genes upregulated in C were mainly involved in inflammatory and immune response, as well as oxidative stress, and relevant canonical pathways and upstream regulators involved in these processes were predicted as activated, such as TNF, IFNB or NFKB. Vitamin E, when supplemented alone at high dose, activated lipid biosynthesis functions, pathways and regulators, this finding being accompanied by increased adipocyte size. Results suggest an improved metabolic and antioxidant status of adipose tissue in animals born from sows supplemented with individual antioxidants, while the combined supplementation barely affected gene expression, with VEHT showing a prooxidant/proinflamatory functional profile similar to C animals. Different hypothesis are proposed to explain this unexpected result. Findings allow a deeper understanding of the processes taking place in adipose tissue of genetically fat animals and the role of antioxidants in the regulation of fat cells function. [ABSTRACT FROM AUTHOR]