Evaluation of the four breeds in synthetic line of Jiaxing Black Pigs and Berkshire for meat quality traits, carcass characteristics, and flavor substances.

To investigate breed characteristics and the effect of hybridization of Jiaxing Black Pig (JBP) with Western breeds, the carcass and meat quality traits and flavor substances such as inosinic acids (IMP), intramuscular fat (IMF) in longissimus muscle (LM) from five breeds including JBP, Berkshire, Berkshire × JBP (BJBP), Duroc × Berkshire × JBP (DBJBP), Duroc × Landrace × JBP (DLJBP) were compared in this study. It was found that water holding capacity (WHC) of LM in JBP was significantly higher than that in the other strains (p < 0.01). Dressing out percentage and lean percentage of JBP were both significantly lower than those in the others (p < 0.01) in connection with their lighter carcass weight and higher subcutaneous fat percentage (p < 0.01). Heterosis was realized in DJBP, DBJBP, and DLJBP since their carcass weight, lean percentage, and loin eye muscle area (LEMA) were markedly higher when compared to JBP, whereas lower than those in Berkshire. Among the breeds, the content of IMF and IMP in the LM of JBP were the highest. These traits were also palpably improved in the crossbreds, especially for DBJBP, of which pork was considered outstanding for containing the most abundant essential amino acids (EAA) and total amino acids (TAA).

Genomic analysis reveals genes affecting distinct phenotypes among different Chinese and western pig breeds.

The differences in artificial and natural selection have been some of the factors contributing to phenotypic diversity between Chinese and western pigs. Here, 830 individuals from western and Chinese pig breeds were genotyped using the reduced-representation genotyping method. First, we identified the selection signatures for different pig breeds. By comparing Chinese pigs and western pigs along the first principal component, the growth gene IGF1R; the immune genes IL1R1, IL1RL1, DUSP10, RAC3 and SWAP70; the meat quality-related gene SNORA50 and the olfactory gene OR1F1 were identified as candidate differentiated targets. Further, along a principal component separating Pudong White pigs from others, a potential causal gene for coat colour (EDNRB) was discovered. In addition, the divergent signatures evaluated by Fst within Chinese pig breeds found genes associated with the phenotypic features of coat colour, meat quality and feed efficiency among these indigenous pigs. Second, admixture and genomic introgression analysis were performed. Shan pigs have introgressed genes from Berkshire, Yorkshire and Hongdenglong pigs. The results of introgression mapping showed that this introgression conferred adaption to the local environment and coat colour of Chinese pigs and the superior productivity of western pigs.

MicroRNA expression profiling of lactating mammary gland in divergent phenotype swine breeds.

MicroRNA (miRNA) plays a key role in development and specific biological processes, such as cell proliferation, differentiation, and apoptosis. Extensive studies of mammary miRNAs have been performed in different species and tissues. However, little is known about porcine mammary gland miRNAs. In this study, we report the identification and characterization of miRNAs in the lactating mammary gland in two distinct pig breeds, Jinhua and Yorkshire. Many miRNAs were detected as significantly differentially expressed between the two libraries. Among the differentially expressed miRNAs, many are known to be related to mammary gland development and lactation by interacting with putative target genes in previous studies. These findings suggest that miRNA expression patterns may contribute significantly to target mRNA regulation and influence mammary gland development and peak lactation performance. The data we obtained provide useful information about the roles of miRNAs in the biological processes of lactation and the mechanisms of target gene expression and regulation.

Characteristic, polymorphism and expression distribution of LCAT gene in a Mongolian gerbil model for hyperlipidemia.

This study aims to evaluate the genetic basis and activity of lecithin cholesterol acyltransferase (LCAT) in a novel Mongolian gerbil model for hyperlipidemia. Gerbils may be susceptible to high fat and cholesterol (HF/HC) diets, which can rapidly lead to the development of hyperlipidemia. Approximately 10-30% of gerbils that are over 8months old and fed controlled diets spontaneously develop hyperlipidemia. Using the HF/HC diet model, we detected triglycerides (TG), total cholesterol (TC), HDL (high density lipoprotein)-C, LDL (low density lipoprotein)-C and LCAT in both old (>8months) and young gerbils. The TC and HDL-C levels were two times higher in old gerbils compared with young gerbils (P<0.01). However, in the old group the LCAT activity fell slightly compared with the normal lipidemia group. It is reasonable to hypothesize that this may be associated with single nucleotide polymorphisms of the LCAT gene. We cloned this gene to investigate the sensitivity of the gerbil to the HF/HC diet and spontaneous hyperlipidemia. The entire LCAT gene was cloned by splicing sequences of RACE (rapid amplification of cDNA ends) and nest-PCR products (AN: KC533867.1). The results showed that the 3683base pair gene consists of six exons and five introns. The LCAT protein consists of 444 amino acid (AA) residues, which are analogous to the human LCAT gene, and includes 24 signal peptide AA and 420 mature protein AA. Expression of LCAT was detected in the kidney, spleen and adrenal tissue, apart from the liver, by immunohistochemistry. The abundance of the protein was greater in the older group compared with the control group. Polymorphisms were analyzed by PCR-SSCP (PCR-single-strand conformation polymorphism) but none were found in 444 animals of the ZCLA closed population (a Chinese cultured laboratory gerbil population).

[Expression of ER, bcl-2, and p53 mRNA in early hybrid embryos of chicken-quail].

Using artificial insemination, 100 female quails were crossed with 10 male chickens. The eggs were collected and hatched in the same incubator. The sex of live hybrid embryos from 66 to 120 hatch hours was determined using multiply PCR of Wpkci. Total 300 male and female embryos at various hatch times were sampled and the relative mRNA abundance of ER, bcl-2, and p53 in the embryos was detected by RT-PCR using beta-actin as the internal standard. The effects of ER, bcl-2, and p53 on the early embryonic development for hybrids between chicken and quail were analyzed. The results showed ER mRNA expression of female hybrids were higher than male hybrids from 66 to 84 hatch hours with a highly significant difference (P<0.01), which indicated that the sex differentiation of hybrids was perhaps happened between 66 to 84 h of embryo stage. The obvious sequential expression of bcl-2 and p53 in the embryonic development indicated that the bcl-2 and p53 genes had an important effect on the development of the hybrid embryos.

[Expression characteristics of prolactin gene in Eastern Zhejiang white geese].

This study was conducted to clone the prolactin gene (PRL) in Eastern Zhejiang White Geese and to investigate the PRL gene expression characteristics during egg-laying, out-of-lay and incubating periods by real time PCR. Comparisons were made respectively of concentration of prolactin mRNA in the hypothalamus, pituitary gland and ovary of the adult female geese at different reproductive periods. The result indicated that there were significant differences (P<0.05) in PRL mRNA expression between different reproductive periods of the geese. The lowest level of PRL expression was found in out-of-lay geese, higher in the egg-laying geese, and the highest in incubating geese. Furthermore, the analysis of PRL expression in different tissues indicated that the highest levels of PRL was expressed in the pituitary gland, followed in hypothalamus, and the least in ovary of the geese. There were significant difference (P<0.01) expression of PRL between the pituitary gland/hypothalamus and ovary of the geese, whereas no any difference was observed between the pituitary gland and hypothalamus (P>0.05). In summary, the PRL mRNA expression had variance in different reproductive periods of the geese.

[Effect of SNP in the exon 8 of SIM1 gene on backfat thickness in pigs].

SNP in exon 8 of the Single-minded 1 (SIM1) gene was detected using PCR-SSCP in 169 pigs of 6 pig breeds including Yorkshire, Duroc, Pietrain, Landrace, Jiaxinghei and Jinhua. The results showed three genotypes (CC, CT, TT) were found and their frequencies between domestic and foreign breeds were different. Only one genotype TT was found in Jiaxinghei and Jinhua pigs, but three genotypes were detected in each foreign breed. The effects of this SNP on backfat thickness in Landrace, Yorkshire and Duroc were estimated using least square method. The homozygote pigs had thicker backfat than the heterozygote ones. The significant effect of various genotypes was found in foreign breeds (P < 0.05). SIM1 had different effects on backfat thickness of different points.

[SNPs of myostatin gene and its genetic effects on carcass traits in chicken].

Two polymorphic sites in the first exon 1 of MSTN gene in 180 Wenling grass-chicken including 3 lines were studied by PCR-RFLP method,and its genetic effects on carcass traits were researched. The results showed that 2 genotypes (MN and NN) in G(2100)A locus were identified by Bsh1236 I and 3 genotypes (AA, AB and BB) in G(2109)A locus were identified by Msp I, and 5 genotypes were emerged while com-analyzing 2 loci. The chi2 test indicated genotype frequencies had no significant deviation (P > 0.05) among lines. The analysis of variance showed that the different genotypes had significant deviation (P <0.01 or P < 0.05) in carcass percent. The multiple comparisons were made. The abdominal fat weight and carcass percent of heterozygosis MN were significantly higher (P<0.05) than that of mutant NN,and the breast muscle weight and breast muscle percent of heterozygosis AB were significantly higher (P < 0.01 or P<0.05) than that of AA individuals. In addition,the abdominal fat weight and abdominal fat percent of AA individuals were significantly higher (P<0.01) than that of mutant BB individuals,but BB individuals were significantly lower (P<0.05) than AA and AB individuals in leg muscle weight trait. The abdominal fat weight,abdominal fat percent and breast muscle percent of genotype NA/MA individuals were significantly higher or lower (P<0.01) than those in other genotype individuals while com-analyzing 2 loci.

[Effects of microsatellite in the regulatory region of IGF1 on growth traits in Jinhua swine].

Insulin-like growth factor 1 (IGF1) and its associated binding proteins and transmembrane receptors (IGFR) play an important role in the physiologic process of mammalian growth. The objectives of present work were to estimate the effects of microsatellite markers located in the 5'-regulatory region of the IGF1 on birth weight (BW), weaning weight (WW), weight at the 120th day, the 180th day and litter weight at birth (LWB) by the least square method in Jinhua pig. Significant effect was found for IGF1 genotype on BW (P<0.05), with positive effects associated with the 286/286 genotype, and 280/286 genotype on LWB in second parity (P>0.05). Furthermore, according to analysis of allele average substitution effect, alleles 274 bp and 286 bp was favourable for BW increase, allele 280 bp was favourable for LWB increase in the second parity. By correlation analysis, total number of birth, number of birth alive and LWB of the second parity in Jinhua pig had highly significant correlation (P<0.01), therefore increasing LWB of the second parity could improve litter performance of Jinhua pig.

[Correlation between porcine CAST gene polymorphism with muscle fiber histological traits and carcass characteristics].

Three polymorphisms were identified in the sixth intron of the CAST gene by PCR-RFLP using enzymes Msp I, Hinf I and Rsa I in 45 Jinpi F2 pigs. However, only three genotypes AACCEE, BBDDFF, and ABCDEF were detected in those pigs and the genotype frequencies were 0.1778, 0.2222 and 0.6000, respectively. Longissimus dorsi muscles were moved for paraffin serial sections and stained with hematoxylin-eosin or myosin heavy chain (MHC) by immunohistochemistry respectively. Fiber cross-sectional area, fiber density, fiber diameter, the rate of MHC type I fiber and the carcass characteristics were recorded. Correlation analysis showed that the skeletal muscle fiber area and the eye muscle area of the BBDDFF individual were significantly higher than those of the ABCDEF individual (P < 0.05).

[The histological characteristics of longissimus dorsi and its correlation with restriction fragments polymorphism of calpastatin gene in f2 Jinghua x Pietrain crossbred pigs].

In order to evaluate the genotype of CAST gene and its relationship with the muscle histology and other postmortem traits. 158 Jinpi F2 pigs were electrically stunned and exsanguinated. The blood and muscle samples were collected, and both postmortem and meat traits were recorded. PCR-RFLP, PAS and myosin heavy chain immunohistochemistry were employed to explore the relationship between the genotypes and the muscle histology. Based on the PAS reactivity, the muscle fibers can be divided into three types: I, II-a and II-b. Myosin heavy chain immunohistochemistry could differentiated the fibers into slow fibers and fast fibers, the ratio of slow fibers and fast fibers is about 7.62% and 92.38% respectively. The amplification products of the region between 6th and 7th exon of CAST gene were digested by HinfI and discriminated 2 polymorphic sites (524bp and 632bp) in endonuclease map. Only 3 genotypes (AA,AB and BB) was distinguished out. The frequency of AA, AB and BB is 0.1795, 0.5897 and 0.2308 respectively. The frequency of A and B is 0.4743 and 0.5256 respectively. Different genotypes had no statistical significant effect on area, water holding capacity, pH value, and conductivity of longissimus dorsi muscle. The results revealed that the genotypes had a significant effect on the aspect ratio of muscle and showed a negative correlation with the percentage of intramuscular connective tissue.

[Influences of MyoG gene on reproductive traits in Jinhua pig].

The genotypes in the second intron and 3' UTR region of myogenin gene in 149 Jinhua pigs (line I, 109; line II, 15; line III, 25) were detected by PCR-RFLP method. The results showed that three genotypes (AA, AB and BB) in the PCR1-MspI-RFLP site were detected and their frequencies were 0.1544, 0.3826, 0.4631, respectively; MM and MN genotypes were found in PCR2-MspI-RFLP site and their frequencies were 0.9953 and 0.0047. The effect of MyoG gene on the reproductive traits was analyzed using SPSS software. Significant associations were found between MyoG locus and total number born (TNB) in first parity (P<0.05), and number born alive (NBA) in the second parity (P<0.05), but no significant associations existed in other parity combinations of TNB, NBA and litter weight birth (LWB) (P<0.05).

[Analysis on effect of microsatellite markers on milk production traits in Simmental].

12 microsatellite markers from 4 chromosomes were chosen to analyze the effect on 5 milk production traits (including fat, lactoprotein, lactose, dry matter content and somatic cell number) of 150 cows from a 6-male-line Simmental breeding core group. Results showed that the 12 microsatellite markers were highly polymorphic and their PIC (polymorphism information contents) were over 0.60, and the marker with the highest PIC (0.85) was ILST093. The heterozygosities were among 0.64 and 0.86. Effects of 12 microsatellite loci on milk production traits were analyzed. Results showed that ILST093 had a significant effect on somatic cell number (P<0.05). Effects of BMS711 on fat ratio and of BMS1905 on lactose both reached a significant level (P<0.05), BM6438 on milk production traits had no significant effect.

[Amplification of pig microsatellite markers using multiplex PCR].

In order to rapidly amplify pig microsatellite markers and save materials,multiplex PCR was used and its reaction condition was optimized. Forty-six combinations of multiplex PCR with good effects were obtained. Thirty of them are duplex-PCRs, sixteen are triplex-PCRs. The results of multiplexes showed that the concentration of primers varied among 0.06 approximately 0.3 micromol/L, the Mg(2+) concentration among 1.5 approximately 3.0 mmol/L; 0.2 approximately 0.4 U of Taq polymerase and 1.0-, 1.2-, 1.4-, 1.6-fold buffer were used, the annealing temperature and the cycle number varied among 52 approximately 60 degrees and 32 approximately 50 degrees, respectively. All multiplexes were further combined into 17 sets for the electrophoresis on ABI 377 sequencer.

[Comparison between the female- and male-linkage maps in pigs].

The difference between the length of female- and male-linkage map, which was created with a reference pedigree based on a commercial porcine population and using 163 microsatellite markers as well as 3 type-I markers (RYR1, PRKAG3, PIT1), was statistic analyzed. The results showed that the total length of female linkage map of autosomes is 2625.9 cm and the total length of the male linkage map is 2259.7 cm; the ratio between the total length of the female- and male-linkage maps is 1.16 : 1; except for the chromosomes 1 and 14, the female linkage maps of the other chromosomes are longer than the male linkage maps. The difference between the length of female- and male-linkage maps of chromosomes 1, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17 and 18 is very significant (P<0.01) and the difference of chromosome 9 is significant (P<0.05); but there is no significance on chromosomes 2, 4, 12 and 15.

[Investigation on the distribution and their effects on reproduction traits of three major genes in Jinhua pigs].

The PCR-RFLP technique was applied to analyze the distribution of estrogen receptor (ESR) gene, follicle-stimulating hormone beta subunit(FSH beta) gene and prolactin receptor (PRLR) gene in three lines of Jinhua pigs. The effect of ESR, FSH beta and PRLR on the reproductive traits was analyzed by the SPSS software. The results showed that: The genotype frequencies of AA, AB, BB for ESR were 0.0237, 0.3609, 0.6154 for Jinhua pig line I, 0, 0.5333, 0.4667 for Jinhua pig line II and 0.2909, 0.6, 0.1091 for Jinhua pig line III, respectively; The genotype frequencies of AA, AB, BB for PRLR were 0.2560, 0.3929, 0.3512 for Jinhua pig line I, 0.2, 0.2667, 0.5333 for Jinhua pig line II and 0.1273, 0.4909, 0.3818 for Jinhua pig line III, respectively; But only the Jinhua pig line I had the polymorphism of FSH beta, and with the low frequency of favorable allele B (0.0120). Significant associations were found for the ESR locus with the number of born alive (NBA) in later parities, the NBA and the total number of born (TNB) of all parities(P < 0.05) and the NBA of later parities (P = 0.061) in Jinhua pig line I. The additive effects of allele B were 0.70 and 0.66 for the NBA in later parities and all parities respectively, and 0.90 and 0.84 for the TNB in later parities and all parities respectively. No significant associations were found for the PRLR locus with the reproductive traits for Jinhua pigs in all parities and significant interactions of ESR and PRLR were found for the TNB and the NBA in all parities (P < 0.05) and for the female birth weight (FBW) in later parities (P < 0.01).