Breast milk is the primary source of nutrition for newborns, and is rich in immunological components. MicroRNAs (miRNAs) are present in various body fluids and are selectively packaged inside the exosomes, a type of membrane vesicles, secreted by most cell types. These exosomal miRNAs could be actively delivered into recipient cells, and could regulate target gene expression and recipient cell function. Here, we analyzed the lactation-related miRNA expression profiles in porcine milk exosomes across the entire lactation period (newborn to 28 days after birth) by a deep sequencing. We found that immune-related miRNAs are present and enriched in breast milk exosomes (p<10−16, χ2 test) and are generally resistant to relatively harsh conditions. Notably, these exosomal miRNAs are present in higher numbers in the colostrums than in mature milk. It was higher in the serum of colostrum-only fed piglets compared with the mature milk-only fed piglets. These immune-related miRNA-loaded exosomes in breast milk may be transferred into the infant body via the digestive tract. These observations are a prelude to in-depth investigations of the essential roles of breast milk in the development of the infant's immune system.
The MyoG gene was sequenced in 63 individuals from 10 breeds (eight Chinese domestic breeds, one recently derived breed and one introduced breed) of pigs in this experiment to analyze the nucleotide sequence diversity of the MyoG gene. The following conclusions can be drawn from the experiment. In the complete sequence of the pig MyoG gene, the content of C+G base is significantly higher than that of A+T. And the high content of G and C base in the coding region caused that bias. In the coding region of the MyoG gene, the G and C base are abundant at the 1 st and the 3 rd site of the codon, especially at the 3 rd site. The high content of G and C base is beneficial for the stability of the MyoG gene. Generally speaking, the MyoG gene is very conservative, the composition and construction of the coding region are very stability, but mutations can be found in noncoding region. Transversion happens with higher frequency than that of transition, and transition happens mainly between T and C base, transversions mainly between G and C base. In the flanking region and intronic region, the MyoG gene has relatively high nucleotide diversity. These mutations exist in noncoding region caused the nucleotide sequence diversity of the MyoG gene.
Abstract In this study, we extracted exosomes from cooked meat by ultra-high-speed centrifugation. Exosome had an average of size of 70.29 nm. Flow cytometry demonstrated that the positive rate of exosomal surface marker CD63 and CD81 were 84.5% and 95.9%. microRNA sequencing revealed the exosomal microRNA were differences among porcine muscle, fat and liver. The mice plasma levels of miR-1, miR-133a-3p, miR-206 and miR-99a were increase with varying degrees after drinking water with exosomes. GTT and ITT suggest that abnormal glucose metabolism and insulin resistance in mice. Moreover, the lipid droplets were significant increased in the liver were also observed. Transcriptome analysis identified 446 differentially expressed genes in liver. Functional enrichment analysis found that metabolic pathway were most significantly enriched. microRNA may function as a critical regulator involved in the metabolic disorder of mice. This study suggests that the exosomal microRNAs from meat products has the potential to adversely affect health.
Uncovering genetic variation through resequencing is limited by the fact that only sequences with similarity to the reference genome are examined. Reference genomes are often incomplete and cannot represent the full range of genetic diversity as a result of geographical divergence and independent demographic events. To more comprehensively characterize genetic variation of pigs ( Sus scrofa ), we generated de novo assemblies of nine geographically and phenotypically representative pigs from Eurasia. By comparing them to the reference pig assembly, we uncovered a substantial number of novel SNPs and structural variants, as well as 137.02-Mb sequences harboring 1737 protein-coding genes that were absent in the reference assembly, revealing variants left by selection. Our results illustrate the power of whole-genome de novo sequencing relative to resequencing and provide valuable genetic resources that enable effective use of pigs in both agricultural production and biomedical research.
Satellite cell is a kind of myogenic stem cells, which plays an important role in muscle development and injury repair. Through proliferation, differentiation and fusion of muscle fiber can satellite cells make new myonuclear, leading to the hypertrophy of skeletal muscle and fiber type transformation, and this would further affect the meat quality. Here, we review the relationship between muscle fiber development and meat quality attributes as well as the influence of the satellite cell differentiation on muscle fiber character. Besides, we also summarize the classical signaling pathway (i.e., Notch etc.) and influence of epigenetic regulation (i.e. miRNA) on muscle quality.
Domesticated organisms have experienced strong selective pressures directed at genes or genomic regions controlling traits of biological, agricultural or medical importance. The genome of native and domesticated pigs provide a unique opportunity for tracing the history of domestication and identifying signatures of artificial selection. Here we used whole-genome sequencing to explore the genetic relationships among the European native pig Berkshire and breeds that are distributed worldwide and to identify genomic footprints left by selection during the domestication of Berkshire. Numerous nonsynonymous SNPs-containing genes fall into olfactory-related categories, which are part of a rapidly evolving superfamily in the mammalian genome. Phylogenetic analyses revealed a deep phylogenetic split between European and Asian pigs rather than between domestic and wild pigs. Admixture analysis exhibited higher portion of Chinese genetic material for the Berkshire pigs, which is consistent with the historical record regarding its origin. Selective sweep analyses revealed strong signatures of selection affecting genomic regions that harbor genes underlying economic traits such as disease resistance, pork yield, fertility, tameness and body length. These discoveries confirmed the history of origin of Berkshire pig by genome-wide analysis and illustrate how domestication has shaped the patterns of genetic variation.
Total number born (TNB), number born alive (NBA), and litter weight born alive (LWB) are critically important traits in pig production. The sow’s parity is one of the major factors influencing litter traits. Because of monogenic or polygenic contributions and the presence of temporal gene effects in different sows’ parities, it is difficult to clarify the biological and genetic background. To systematically explore the genetic mechanism of litter traits, we conducted 18 GWASs using single-step GWAS (ssGWAS) based on two breeds (908 Landrace and 1,130 Large White sow litter records) for each litter trait in different parities. A total of 300 Landrace and 300 Large White sows were genotyped by sequencing (GBS). ssGWAS was performed separately for each breed and each parity due to population stratification and temporal gene effect. In summary, we identified 80 (15 for Landrace and 65 for Large White), 227 (52 for Landrace, 175 for Large White), and 187 (34 for Landrace, 153 for Large White) single nucleotide polymorphisms (SNPs) affecting TNB, NBA, and LWB, respectively. Of them, we suggest that a total of 22 loci (SSC1: 125098202, SSC1: 117560058, SSC14: 147794697, SSC8: 84823302, SSC9: 143554876, and SSC9: 138766097 for Landrace; SSC1: 4023577, SSC1: 3859573, SSC1: 4891063, SSC16: 5197665, SSC10: 32050819, SSC13: 13552924, SSC13: 92819, SSC17: 3579607, SSC13: 196698221, SSC7: 30918403, SSC16: 46221484, SSC16: 46169204, SSC2: 41988642, SSC2: 44475457, SSC2: 42521875, and SSC7: 58411951 for Large White) are shared by TNB, NBA, and LWB. These results indicate the existence of gene temporal effect in each parity. Furthermore, our findings suggest four interesting candidate genes (FBXL7, ALDH1A2, LEPR, and DDX1) associated with litter traits in different parities that have a major effect on embryonic development progression. In conclusion, 22 crucial SNPs and four interesting candidate genes were identified for three litter traits across six parities. These findings advance our understanding of the genetic architecture of litter traits and confirm the presence of temporal gene effects in different parities. Importantly, functional validation studies for findings of particular interest are recommended in litter traits.
Records on 47,360 Yorkshire, 28,762 Landrace, 14,020 Duroc, and 9,983 Hampshire pigs for backfat depth and days to 100 kg made between 1989 and 1992 in herds on the Ontario Swine Improvement Program (OSIP) were used to estimate additive genetic (animal), common environmental (litter), and residual variances and covariances of the two traits. Analysis was by the DFREML program of K. Meyer using a multiple-trait individual animal model with fixed effects of genetic groups and herd-year-season-sex and random effects of animal, litter, and residual. A complete relationship matrix was used. Heritabilities were .51, .53, .55, and .50 for backfat and .31, .30, .26, and .32 for days to 100 kg in Yorkshire, Landrace, Duroc, and Hampshire, respectively. Genetic correlations between backfat and days to 100 kg were −.16, −.06, −.17, and −.10 for Yorkshire, Landrace, Duroc, and Hampshire. Respective pheno-typic correlations were −.08, −.04, −.12, and −.09. Litter effects were large, particularly for days to 100 kg. Resulting common environmental (c 2) effects were .11, .10, .10, and .11 for backfat and .26, .27, .29, and .22 for days to 100 kg for Yorkshire, Landrace, Duroc, and Hampshire. Estimates were highly consistent across breeds and average heritabilities of backfat and days to 100 kg were .52 and .30. Corresponding average c2 effects were .10 and .26. Average genetic and phenotypic correlations between backfat and days to 100 kg were −.13 and −.08.
miRNA is a small non-coding RNA, which plays an important role in diverse biological processes. In the present study, we explore the effect of ssc-miR-451 on porcine adipose development and meat quality. We observed that ssc-miR-451 was downregulated during porcine primary adipocyte differentiation. Overexpression of ssc-miR-451 inhibited adipogenic differentiation, while inhibition of ssc-miR-451 promoted adipogenic differentiation. The dual luciferase reporter system indicated Acetyl-CoA carboxylase alpha (ACACA) as a target gene of ssc-miR-451. Correlation analysis negatively correlated miR-451 expression with intramuscular fat content (IMF) and positively correlated ACACA expression with IMF. Further analysis of fatty acid composition revealed that pigs with high expression of ssc-miR-451 had higher monounsaturated fatty acid (MUFA) and lower polyunsaturated fatty acid (PUFA). Taken together, our study suggests that ssc-miR-451 regulates lipid deposition and fatty acid composition by targeting ACACA, and ssc-miR-451 may serve as a potential genetic marker to improve pork quality.
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