Genetic parameter estimation and gene association analyses for meat quality traits in open-air free-range Iberian pigs.

Meat quality of Iberian pigs is defined by the combination of their genetic characteristics and the particular production system. To carry out a genetic analysis of the main meat quality traits, we estimated their heritabilities, genetic correlations and the association effects of 32 selected SNPs of 12 candidate genes. A total of ten traits were measured in longissimus dorsi samples from 1,199 Iberian pigs fattened in the traditional free-range system: water holding capacity (thawing, cooking and centrifuge force water losses), instrumental colour (lightness L*, redness a* and yellowness b*), myoglobin content, shear force on cooked meat, and shear force and maximum compression force on dry-cured loin. Estimated heritability values were low to moderate (0.01 to 0.43) being the lowest for L* and the highest for cooking loss. Strong genetic correlations between water holding capacity traits (0.93 to 0.96) and between myoglobin content and a* (0.94) were observed. The association analyses revealed 19 SNPs significantly associated with different traits. Consistent and strong effects were observed between PRKAG3 SNPs (rs319678464G > C and rs330427832C > T), MYH3_rs81437544T > C, CASP3_rs319658214G > T and CTSL_rs332171512A > G and water losses. Also for CAPN1_rs81358667G > A and CASP3_rs319658214G > T and shear force. The SNPs mapping on PRKAG3 showed the highest effects on Minolta colour traits. Genotyping of these SNPs could be useful for the selection of Iberian young boars with similar estimated breeding values for productive traits.

Age-related differences to neck muscle activation latency as a potential risk factor to fall-related traumatic brain injuries.

This investigation examined age-related differences in neck muscle activation latency in response to anterior and posterior postural perturbations to understand the potential implications in fall-related traumatic brain injuries. 57 adults were recruited and categorized into 3 groups based on age: Young (18-30 years old), Young-Old (60-74 years) and Old-Old (75-89 years) group. Study participants underwent six anterior and posterior postural perturbations while bilateral sternocleidomastoid, upper trapezius, and splenius capitis electromyography was collected. Muscle activation latency time was calculated with established procedures. During anterior translations, a significant group effect for muscle activation latency of the right SCM (F(2,43) = 8.786, p < 0.001), right (F(2,34) = 4.838, p = 0.014) and left (F(2,34) = 5.015, p = 0.012) upper trapezius, and right (F(2,45) = 3.195, p = 0.050) and left (F(2,45) = 3.819, p = 0.029) splenius capitis was observed. During posterior translations, a significant group effect for muscle activation latency was observed in the right (F(2,34) = 6.419, p = 0.004) and left (F(2,41) = 5.275, p = 0.009) SCM, and the right (F(2,34) = 4.925, p = 0.013) and left (F(2,32) = 4.055, p = 0.027) upper trapezius. Both older groups displayed longer muscle activation latencies than the young group. The age-related differences in neck muscle activation latency may be placing older adults at a greater risk of fall-related traumatic brain injuries.

Transcriptome and DNA Methylation Analyses of the Molecular Mechanisms Underlying with Longissimus dorsi Muscles at Different Stages of Development in the Polled Yak.

DNA methylation modifications are implicated in many biological processes. As the most common epigenetic mechanism DNA methylation also affects muscle growth and development. The majority of previous studies have focused on different varieties of yak, but little is known about the epigenetic regulation mechanisms in different age groups of animals. The development of muscles in the different stages of yak growth remains unclear. In this study, we selected the longissimus dorsi muscle tissue at three different growth stages of the yak, namely, 90-day-old fetuses (group E), six months old (group M), and three years old (group A). Using RNA-Seq transcriptome sequencing and methyl-RAD whole-genome methylation sequencing technology, changes in gene expression levels and DNA methylation status throughout the genome were investigated during the stages of yak development. Each group was represented by three biological replicates. The intersections of expression patterns of 7694 differentially expressed genes (DEGs) were identified (padj < 0.01, |log2FC| > 1.2) at each of the three developmental periods. Time-series expression profile clustering analysis indicated that the DEGs were significantly arranged into eight clusters which could be divided into two classes (padj < 0.05), class I profiles that were downregulated and class II profiles that were upregulated. Based on this cluster analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that DEGs from class I profiles were significantly (padj < 0.05) enriched in 21 pathways, the most enriched pathway being the Axon guidance signaling pathway. DEGs from the class II profile were significantly enriched in 58 pathways, the pathway most strongly enriched being Metabolic pathway. After establishing the methylation profiles of the whole genomes, and using two groups of comparisons, the three combinations of groups (M-vs.-E, M-vs.-A, A-vs.-E) were found to have 1344, 822, and 420 genes, respectively, that were differentially methylated at CCGG sites and 2282, 3056, and 537 genes, respectively, at CCWGG sites. The two sets of data were integrated and the negative correlations between DEGs and differentially methylated promoters (DMPs) analyzed, which confirmed that TMEM8C, IGF2, CACNA1S and MUSTN1 were methylated in the promoter region and that expression of the modified genes was negatively correlated. Interestingly, these four genes, from what was mentioned above, perform vital roles in yak muscle growth and represent a reference for future genomic and epigenomic studies in muscle development, in addition to enabling marker-assisted selection of growth traits.

Muscle Gain after Transjugular Intrahepatic Portosystemic Shunt Creation: Time Course and Prognostic Implications for Survival in Cirrhosis.

PURPOSE: To examine the association of transjugular intrahepatic portosystemic shunt (TIPS) creation with muscle gains and patient mortality, and to identify the timeframe of these changes. MATERIALS AND METHODS: Patients with cirrhosis undergoing TIPS creation with available abdominal computed tomography before and after TIPS from 2004-2015 were included (n = 76). The primary indications for TIPS included refractory ascites (52.6%) or variceal bleeding (47.4%). Axial truncal muscle area and attenuation were measured at the L4 level using free-hand region of interest technique, and pre- and post-TIPS values were compared. The association of TIPS-related muscle changes with mortality was evaluated using Cox multiple regression. Logistic regression analysis was performed to evaluate associations of baseline muscle area and clinical variables with post-TIPS changes. RESULTS: TIPS creation was associated with significant increases in psoas, paraspinal, and total muscle areas (P < .001, 0.004, and 0.002), and psoas muscle attenuation (P = .022) at a median of 13.5 months after TIPS. Maximal muscle gains occurred within 6 months after TIPS creation (P < .001). Muscle gain at 1-year after TIPS was independently associated with lower mortality (psoas hazard ratio [HR] 0.14, P = .016; paraspinal HR 0.15, P = .016; abdominal HR 0.05, P = .005; core HR 0.06, P = .001; and total HR 0.05, P = .003). Baseline demographic or clinical variables were not associated with muscle gain after TIPS. CONCLUSIONS: TIPS creation was strongly associated with truncal muscle gains and attenuation in patients with cirrhosis. Maximal muscle gain occurred within 6 months after TIPS creation. TIPS-related increased muscle mass was independently associated with lower patient mortality.

Comparing the mRNA expression profile and the genetic determinism of intramuscular fat traits in the porcine gluteus medius and longissimus dorsi muscles.

BACKGROUND: Intramuscular fat (IMF) content and composition have a strong impact on the nutritional and organoleptic properties of porcine meat. The goal of the current work was to compare the patterns of gene expression and the genetic determinism of IMF traits in the porcine gluteus medius (GM) and longissimus dorsi (LD) muscles. RESULTS: A comparative analysis of the mRNA expression profiles of the pig GM and LD muscles in 16 Duroc pigs with available microarray mRNA expression measurements revealed the existence of 106 differentially expressed probes (fold-change > 1.5 and q-value < 0.05). Amongst the genes displaying the most significant differential expression, several loci belonging to the Hox transcription factor family were either upregulated (HOXA9, HOXA10, HOXB6, HOXB7 and TBX1) or downregulated (ARX) in the GM muscle. Differences in the expression of genes with key roles in carbohydrate and lipid metabolism (e.g. FABP3, ORMDL1 and SLC37A1) were also detected. By performing a GWAS for IMF content and composition traits recorded in the LD and GM muscles of 350 Duroc pigs, we identified the existence of one region on SSC14 (110-114 Mb) displaying significant associations with C18:0, C18:1(n-7), saturated and unsaturated fatty acid contents in both GM and LD muscles. Moreover, we detected several genome-wide significant associations that were not consistently found in both muscles. Further studies should be performed to confirm whether these associations are muscle-specific. Finally, the performance of an eQTL scan for 74 genes, located within GM QTL regions and with available microarray measurements of gene expression, made possible to identify 14 cis-eQTL regulating the expression of 14 loci, and six of them were confirmed by RNA-Seq. CONCLUSIONS: We have detected significant differences in the mRNA expression patterns of the porcine LD and GM muscles, evidencing that the transcriptomic profile of the skeletal muscle tissue is affected by anatomical, metabolic and functional factors. A highly significant association with IMF composition on SSC14 was replicated in both muscles, highlighting the existence of a common genetic determinism, but we also observed the existence of a few associations whose magnitude and significance varied between LD and GM muscles.

Genomic regions and enrichment analyses associated with carcass composition indicator traits in Nellore cattle.

The aim of this study was to estimate genetic parameters and identify genomic regions associated with carcass traits obtained by ultrasound and visual scores in Nellore cattle. Data from ~66,000 animals from the National Association of Breeders and Researchers (ANCP) were used. The variance components for backfat thickness, rump fat thickness and Longissimus muscle area (LMA) were estimated considering a linear model whereas a threshold model for body structure (BS), finishing precocity (FP) and musculature (MS) traits. The SNP solutions were estimated using the ssGBLUP approach by considering windows of 10 consecutive SNPs. Regions that accounted for more than 1.0% of the additive genetic variance were used. Genes identified within the significant windows, such as FOXA3, AP2S1, FKRP, NPASI and ATP6V1G1, were found to be related with MS, while OMA1 and FFGY with BS and FP traits. The PLTP, TNNC2 and GPAT2 genes were found in the regions associated with LMA, as well as TKT, FNDC5 and CHRND can strongly be related with fat deposition. Gene enrichment analysis revealed processes that might be directly influenced the organism growth and development. These results should help to better understand the genetic and physiological mechanisms regulating growth and body composition, muscle tissue development and subcutaneous fat expression, and this information might be useful for future genomic studies in Nellore cattle.

Dynamics of myosin heavy chain isoform transition in the longissimus muscle of domestic and wild pigs during growth: a comparative study.

Dynamics of myofiber differentiation/maturation in porcine skeletal muscle is associated with domestication, breeding and rearing conditions. This study was aimed to comparatively elucidate the age-dependent myosin heavy chain (MyHC) isoform expression and transition pattern in domestic and wild pig (WP) skeletal muscle from birth until adulthood. Domestic pigs (DPs) of Large White breed raised in conventional production system were compared with WPs reared in a large hunting enclosure. Muscle samples for immuno/enzyme histochemistry were taken from the longissimus dorsi muscle within 24 h postmortem at 24 to 48 h, 21 to 23 days, 7 months and ~2 years postpartum. Based on the antibody reactivity to MyHCs (NCL-MHCs, A4.74, BF-F3) and succinate dehydrogenase activity, myofibers were classified into I, I/IIa, IIa, IIx and IIb types. In addition, foetal MyHC expression was determined with the use of F158.4C10 antibody. Maturation of the longissimus dorsi muscle in the WP was characterized by an accelerated transformation of the fast to slow MyHC during the first hours postpartum, followed by differentiation towards oxidative myofibers in which type I, IIa and IIx MyHCs predominated. In the DP, the transformation shifted towards glycolytic myofibers that expressed MyHC-IIb. The expression of foetal MyHC was higher in the DP than in the WP at 1 day of age, and the decline in the foetal MyHC during the first 3 weeks was more rapid in the WP than in the DP denoting an accelerated early postnatal muscle maturation in WP than DP piglets. All foetal MyHC-positive myofibers co-expressed IIa isoform, but not vice versa. The intense myofiber hypertrophy was evident from 3 weeks until 7 months of age. In this period, the myofiber cross-sectional area increased up to 10- and 20-fold in the WP and the DP, respectively. In the DP, the hypertrophy of all myofiber types was more pronounced than in the WP, particularly the hypertrophy of IIx and IIb myofibers. To summarize, the comparison between growing DP with wild ancestors showed that genetic selection and rearing conditions lead to substantial changes in the direction and intensity of postnatal MyHC transformation as evidenced by different proportion of individual myofiber types and differences in their hypertrophic potential.

The fatty degeneration of lumbar paraspinal muscles on computed tomography scan according to age and disc level.

BACKGROUND CONTEXT: Spinal degeneration can occur not only in the bone and disc but also in muscles. Fatty infiltration (FI) and decreased volume have been described as characteristic changes that occur in muscle degeneration. Many studies about the lumbar paraspinal muscles have been conducted on patients with spine problems. However, the natural changes of age-dependent degeneration in the paraspinal muscles have not been studied properly. PURPOSE: The purpose of this study is to investigate age- and level-dependent changes of the lumbar paraspinal muscles in the population without lumbar spinal symptoms. STUDY DESIGN: This study is a retrospective case-control study. PATIENT SAMPLE: A total of 887 patients who underwent computed tomography scan for abdomen and pelvis (APCT) between January 2013 and December 2013 were enrolled. After excluding 237 patients with medical history of spine surgery, low back pain, myopathy, muscular dystrophy, infectious disease, vertebral fracture, and deformity, 650 patients were finally subjected to this study. OUTCOME MEASURE: The patients were divided into three age groups: young (20-39 years old), middle (40-59 years old), and old (60-89 years old). The degree of FI was checked twice for multifidus muscle (MF), erector spinae muscle (ES), and psoas muscle (PS) at each disc level from L1 to S1 on APCT by two investigators. The FI was measured as the Hounsfield unit, a mean density (MD) on CT. METHODS: The age differences were compared with the data of the young group, and the level differences were compared with the data of the L1-L2 level. Student t test and intraclass correlation coefficient were checked for statistical analysis. RESULTS: The gender ratio was not significantly different among the groups. Comparing with the young group, the MD of MF significantly decreased at L5-S1 in the middle group (p<.05), and at L3-L4-L5-S1 in the old group (p<.05). The MD of ES was significantly decreased at all levels in the old group (p<.05) but not significant in the middle group. Comparing with the L1-L2 level, the MD of MF significantly decreased at L5-S1 in the middle group (p<.05) and at L4-L5-S1 in the old group (p<.05). The MD of ES was significantly decreased at L5-S1 in the young and middle groups (p<.05) and at L4-L5-S1 in the old group (p<.01) compared with those at L1-L2. According to the age- and level-dependent changes of MD in the MF and ES, there was a tendency of progressive increase of FI in the muscles with age, which seemed to start from L5-S1 and spread to the upper levels. The age-dependent fatty degeneration appeared wider in the ES than the MF. The level-dependent FI of the ES showed a similar pattern with the MF, but the change of the ES seemed to start earlier in age than the MF at the L5-S1. There was no significant MD change in the PS according to age and level. Intraobserver and interobserver reliabilities were both high across all of the muscles (0.86-0.94 and 0.83-0.92). CONCLUSIONS: As a result, the degree of intramuscular fat infiltration seems to be affected by age, disc level, and muscle type. It seems to be more prominent in the extensor muscles, extending from lower to upper levels.

The longissimus thoracis muscle proteome in Alentejana bulls as affected by growth path.

Beef production is an important economic activity. In Southern Europe there are two types of beef production systems based on growth paths: continuous (CG) versus discontinuous growth (DG). DG is a traditional system dependent on pasture; whereas in CG animals are supplemented on concentrate feed. We compare the protein abundance profiles of the longissimus thoracis (LT) muscle in CG and DG animals using label-free quantitative proteomics. Twenty three Alentejana male calves (9months-old, 239kg live-weight) were allocated to two feeding regimens. In CG (n=12) production system, animals were fed ad libitum on concentrates plus hay and slaughtered at 18months. In DG (n=11) production system, animals were fed ad libitum on hay from 9 to 15months of age and then the same diet provided to the CG group and slaughtered at 24months. The LT muscle was sampled and protein abundance profiles determined using label-free quantification. We identified 510 proteins, of which 26 showed differential abundance. Several proteins (e.g. Myozenin-2, glyoclythic enzymes and 14-3-3 protein zeta/delta) are proposed as indicators of a more intensive growth path. Myosin binding protein H had higher abundance in the DG group, suggesting it could be associated to discontinuous growth path.

Changes in Brown Adipose Tissue and Muscle Development during Infancy.

OBJECTIVE: To examine the relationship between brown adipose tissue (BAT) and muscle development, two tissues that derive from a common cell lineage, during the first 6 months of postnatal life. STUDY DESIGN: Thirty healthy term infants (15 males and females) underwent whole-body magnetic resonance imaging examinations. Measurements of BAT in the supraclavicular area as well as measures of trunk musculature and subcutaneous adiposity were obtained at birth and at 6 months of age. RESULTS: Paraspinous musculature and subcutaneous white adipose tissue (WAT) increased, and the proportion of BAT in the supraclavicular area decreased during infancy. Although measures of BAT did not correlate with paraspinous musculature through the first 6 months of life (r = -0.35; P = .09), BAT was a significant predictor of paraspinous musculature after adjusting for weight, body length, and WAT (P = .002); infants with the smallest decreases in BAT had the greatest gains in musculature. In contrast, changes in BAT did not predict increases in subcutaneous WAT (P = .25) during infancy, which were primarily determined by body weight. CONCLUSIONS: Changes in BAT are associated with muscle development but not WAT accumulation in healthy infants. Studies are needed to determine the mechanism(s) by which BAT could facilitate muscle growth, and the degree to which decreased muscle mass, such as in preterm and low birth weight infants, is related to a deficiency of BAT.

Expression of MMP-1, -2, and -8 in longissimus dorsi muscle and their relationship with meat quality traits in cattle.

The extracellular matrix (ECM) is the major macromolecule in skeletal muscle, which affects meat quality greatly. The remodeling of the ECM is mainly regulated by matrix metalloproteinases (MMPs). The expression patterns of MMP-1, -2, and -8 in longissimus dorsi muscle were explored using quantitative real-time polymerase chain reaction. The results show that the expression of MMP-1, -2, and -8 decreased significantly from 135 days of pregnancy to postnatal 30 months. While the expression of MMP-1, -2, and -8 showed no significant relationships with intramuscular fat contents, MMP-1 and -2 showed significant negative correlations with the shearing force of the longissimus dorsi muscle in cattle. The expression of MMP-1 also showed a significant negative correlation with cooking loss and a positive correlation with water holding capacity. The expression levels of MMP-1 and -2 were usually higher in fat than in skeletal muscle tissue. The expression of MMP-8 was significantly higher in the mammary fat pad and the longissimus dorsi muscle than in all other tissues. This study indicates that the remodeling of the ECM has important effects both on the development of postnatal skeletal muscle and on meat quality.

The effect of immunocastration and a diet based on granulated barley on growth performance and carcass, meat and fat quality in heavy gilts.

A total of 48 Duroc × (Landrace × Large White) gilts of 33.2 kg BW were used to investigate the influence of immunocastration and diet on growth performance and carcass, meat and fat quality. Four treatments were arranged factorially (2 × 2) with two sexes (immunocastrated gilts: IG v. entire gilts: EG) and two dietary treatments (a commercial feedstuff as control v. granulated barley as a single major ingredient) provided during the finishing period (from 103 to 126 kg BW). There were four replicates of three pigs per treatment. At the end of the trial, the IGs grew faster (P<0.05) and ate more feed (P<0.05) than the EGs. Carcasses from the IGs had thicker backfat depth than those from the EGs (P<0.01) and carried out a lower percentage of rejected carcasses (P<0.05) at slaughterhouse owing to lack of fat. Meat from the IGs tended to have higher intramuscular fat (IMF) content in the Longissimus thoracis (LT) muscle than that from the EGs (P=0.09). In addition, immunocastration increased the total saturated fatty-acid proportion in subcutaneous fat and IMF (P<0.001) and decreased the total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) percentages in subcutaneous backfat (P<0.05 and P<0.001, respectively) and in IMF (P<0.01 and P=0.06, respectively). The use of a diet based on granulated barley during the finishing period had no effect on growth performance but tended to increase IMF content in the LT muscle (P<0.06), and increased MUFA (P<0.05) and decreased PUFA (P<0.01) proportions in omental fat. It is concluded that immunocastration of gilts intended for dry-cured ham industry improved some aspects of growth performance and carcass and meat quality, whereas granulated barley had scarce effect on productive traits and fatty-acid profile but tended to improve IMF content.