H-FABP gene expression and genetic association with meat quality traits in domestic pigeons (Columba livia).

1. H-FABP (heart-type fatty acid-binding protein) is an important fatty acid-binding protein that participates in the metabolism and intracellular transportation of lipids. This study was designed to study the H-FABP gene expression and genetic association with meat quality traits in domestic pigeons.2. The spatio-temporal expression patterns showed that H-FABP was widely expressed in all eleven tissues in birds from hatching to 4 weeks of age, and the expression level in the liver was the highest, and spleen and subcutaneous fat showed relatively high levels at all time points, and increased markedly as squabs became older.3. Nine novel SNPs were found; three of them (g.42 C > T and g.123 C > T in exon 1 and g.3128 C > T in exon 2) were synonymous mutations, and six of them (g.3304 T > C, g.3305 G > A, g.3313A>G, g.3343 C > T, g.3372A>C, g.3410 T > C in exon 3) were located in the 3' untranslated region (UTR). In addition, four haplotypes and six diplotypes were formed and showed weak linkage disequilibrium. Association analysis showed that in the SNP of g.3305 G > A, the AB genotype showed higher (P < 0.05) inosinic acid concentrations in breast muscle than the BB genotype. In the SNP of g.3313A>G, the AA and AB genotypes showed significantly higher (P < 0.01) inosinic acid concentrations than the BB genotype, AA showed the highest intramuscular fat content, and the relative mRNA expression level of the AA genotype was the highest (P < 0.05).4. Association analysis of diplotypes showed no correlation with meat quality traits. Moreover, correlation analysis indicated that the H-FABP mRNA expression level was tightly related to intramuscular fat content (P < 0.01).5. This study suggested that the H-FABP gene may be a candidate gene in marker-assisted selection of pigeons for high-quality meat.

Association of DGAT2 gene polymorphisms with carcass and meat quality traits in domestic pigeons (Columba livia).

1. Diacylglycerol acyltransferase (DGAT) plays an important role in the synthesis of triacylglycerol, but its effects on meat quality and carcass composition in pigeons are unclear. In this study, single-nucleotide polymorphisms (SNPs) in the exons of the DGAT2 gene were identified and analysed by using DNA sequencing methods in 200 domestic pigeons (Columba livia). The associations between DGAT2 polymorphisms and carcass and meat quality traits were also analysed. 2. Sequencing results showed that 5 nucleotide mutations were detected in exons 3, 4, 5 and 6 of the DGAT2 gene. The analysis revealed three genotypes (AA, AB and BB) in G18398T and G22484C, in which the AA genotype and A allele had the highest frequency. 3. In the SNP of G18398T located in exon 5, individuals with genotype BB had significantly higher meat quality and lower abdominal fat content than those with AA or AB genotype. In the SNP of G22484C located in exon 6, the genotype AA showed highest carcass trait values, while the genotype BB represented better meat quality, compared to AA and AB genotypes. 4. The results imply that DGAT2 gene has a close relationship with carcass and meat quality traits in pigeons, and the SNPs of G18398T and G22484C can be used as genetic markers for marker-assisted breeding in pigeon.

Association of ADSL gene polymorphisms with meat quality and carcass traits in domestic pigeons (Columba livia).

1. Adenylosuccinate lyase (ADSL) plays an important role in the synthesis of inosine monophosphate (IMP). In this trial, a total of 200 pigeons were sampled and slaughtered. Seven meat quality traits and 11 carcass traits were measured. DNA sequencing was used to detect nucleotide mutations, and associations between ADSL gene polymorphisms and meat quality and carcass traits were analysed. 2. Sequencing results showed that 9 nucleotide mutations were found in the exons of the ADSL gene. All the mutations were synonymous except C13065G, which caused a change in amino acids (Ser to Arg). In addition, two of the detected single nucleotide polymorphisms (SNPs) had significant associations with meat quality and carcass traits. 3. For the C13065G SNP located in exon11, the IMP content of breast muscle in AA and AB genotype was higher than in the BB genotype (P < 0.01). The SNP G10696A located in exon10 was significantly associated with carcass rate, in which AA and AB genotype were higher than the BB genotype (P < 0.01). 4. The results indicated that the ADSL gene has a close association with meat quality and carcass traits in domestic pigeons, and G10696A and C13065G SNPs could be applied as genetic markers in molecular marker-assisted breeding of pigeons.

Molecular cloning and expression analysis of the GNAS gene in pig and porcine fibroblast cells.

The Alpha subunit of the stimulatory guanine nucleotide-binding protein (GNAS) is a complex imprinted gene. The major product of the GNAS gene is the α-subunit of the guanine nucleotide-binding protein (Gas), which plays a key role in multiple signal transduction pathways. Gas is required for the production of the receptor-stimulated intracellular cyclic adenosine monophosphate (cAMP). It has been demonstrated that an increase in the concentration of the intracellular second messenger cAMP promotes apoptosis in different tumor entities. Mutations of GNAS have also been identified in many tumors. This study aimed to investigate the expression pattern and the apoptosis effect in fibroblast cells for porcine GNAS. The results show that GNAS mRNA was detected in a wide range of tissues, especially in the longissimus dorsi muscle and thyroid gland. The developmental pattern of GNAS mRNA in the thyroid gland of Jinhua pigs was then examined; however, there was no significant difference (P > 0.05) among any of the stages. GNAS gene expression was relatively stable in the thyroid gland during the entire growth and development process. The developmental pattern of GNAS mRNA in the longissimus dorsi muscle was significantly different among the various developmental stages (P < 0.01). GNAS mRNA was strongly expressed at 60 days, 90 days, and 150 days after birth, whereas the expression level was very low during the embryo stages. Target RNA interference of GNAS in porcine fibroblast cells leads to lower mRNA expression of Bcl-2, Fas, and Caspase-3, which are recognized as apoptosis related markers.

Influence of castration-induced sex hormone deficiency on serum lipid levels and the genes expression in male pigs.

It has been known that the changes in gonadal steroids are closely associated with adipose tissue metabolism. Domestic pigs have been a well-recognized experimental animal in biomedical research because of their similarity to humans in body size and other physiological/anatomical features. The aims of this study were to investigate the influence of castration-induced sex hormone deficiency on serum lipid levels and the genes expression of key enzymes associated with lipogenic and lipolytic processes in male pigs. The experimental animals consisted of 2 groups slaughtered on 147th and 210th day, respectively. In each of the group, 7 full-sib pairs of castrated and intact male hybrids from Yorkshire dams sired by Landrace were contained. The results showed that castration of male pigs led to increased total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, and leptin levels in serum (p<0.05). No differences in levels of the free fatty acid, insulin, and glucose were observed between boars and barrows (p>0.05). Castration caused upregulation of fatty acid synthase and acetyl-CoA carboxylase alpha genes expression at both 147 and 210 days of age (p<0.05). No differences in expression of hormone sensitive lipase and adipose tissue triglyceride lipase genes were observed between boars and barrows at either 147 or 210 days of age (p>0.05). It is speculated that higher body fat deposition in castrated male pigs might have resulted mainly from increased transcription of the lipogenic genes, but not from decreased transcription of the lipolytic genes.

Mapping, expression and regulation of the TRα gene in porcine adipose tissue.

Thyroid hormone receptors (TR) are members of the nuclear receptor superfamily. There are at least two TR isoforms, TRα and TRß. The TRα isoform plays a critical role in mediating the action of thyroid hormone in adipose tissue. We mapped the porcine TRα gene to chromosome 12 p11-p13, by using the ImpRH panel. We examined tissue-localization of TRα and determined expression patterns of TRα in porcine adipose tissue with quantitative real-time PCR. TRα was expressed in all tissues, including heart, liver, spleen, stomach, pancreas, brain, small intestine, skeletal muscle, and subcutaneous adipose tissue. In the adipose tissue, the expression of TRα decreased postnatally. Compared to Yorkshire pigs, Jinhua pigs had significantly lower expression levels of TRα gene in the subcutaneous fat tissue. The expression levels of ß2-AR, HSL and ATGL were also significantly lower in Jinhua pigs than in Yorkshire pigs. However, no significant differences in PPARγ and SREBP-1C expression levels were found between Jinhua and Yorkshire pigs. Incubation of porcine adipose tissue explants with high doses of isoproterenol (100 and 1000 nM) significantly increased the expression levels of TRα. We conclude that there is considerable evidence that TRα plays an important role in fat deposition in porcine adipose tissue.

Corticotropin-releasing factor receptor type 1 and 2 mRNA expression in the rat anterior pituitary is modulated by intermittent hypoxia, cold and restraint.

We had previously demonstrated that continual-hypoxia stimulated corticotropin-releasing factor (CRF)mRNA in hypothalamus, and release of CRF, as well as enhancing plasma adrenocorticotropic-hormone and corticosterone of rats. The present study demonstrates using in situ autoradiography that CRF receptor 1 (CRFR1) and CRF receptor 2 (CRFR2) mRNA in the rat anterior pituitary is changed by intermittent hypoxia, cold, restraint, alone and in combination. Rats were exposed to intermittent hypoxia for 4 h/day during various periods in a hypobaric chamber. Hypoxia equivalent to an altitude of around 2 km (16.0% O2) or 5 km (10.8% O2) caused a biphasic change in both CRFR1 and R2 mRNA, there being an initial significant decline on day 1 and then an enhancement by day 2. The increase of both receptor subtypes mRNA was relatively well maintained up to 15 days in rats exposed to 2 km intermittently. CRFR2 mRNA in rats exposed to 5 km, after peaking at day 2 therefore declined and was not different to controls at 15 days. Five kilometer hypoxia markedly reduced body weight gain. The increased CRFR1 mRNA was also induced by restraint alone, hypoxia+restraint and hypoxia+cold but not by cold alone. The CRFR2 mRNA was significantly increased by all the stresses except for hypoxia+restraint. These results show that the acute response to intermittent hypoxia is a decrease in the CRF receptor mRNA whereas longer exposure to the three environmental stressors hypoxia, cold and restraint is needed to provoke an increase. This may have important consequences for adaptation to high altitude. The significant differences between the expression of CRFR1 mRNA and CRFR2 mRNA in response to the different stimuli might suggest that the two receptors in the pituitary play different roles in behavior.

[Study of mapping QTLs for milk traits on the German dairy cattle].

A total of 1,130 bulls belonging to 20 half-sib families of German dairy cattle were genotyped for 229 microsatellite markers on 30 chromosomes. The data were used in an attempt to map quantitative trait loci applying regression as multiple-marker regression. For association analysis with a granddaughter design, the estimated breeding values for 3 milk traits were used: milk production, fat production and protein production. The empirical values of significance thresholds were determined by using a permutation test on the experimental data. Several significant QTLs were found on some chromosomes, especially on the chromosome 14. The results give a strong support for the experiments of Coppieters et al. and Ron et al.

Molecular cloning, expression and polymorphism of the porcine apolipoprotein A5 gene in a Jinhua × Pietrain F2 reference population.

As a newly described member of the apolipoprotein gene family, apolipoprotein A5 (APOA5) has been suggested to play a key role in the triglyceride metabolism in both human and mice. The aim of this study was to identify the porcine (Sus scrofa) APOA5 gene, determine its mRNA and its mutations that are associated with lipid accumulation. The porcine APOA5 cDNA was amplified by reverse transcriptase polymerase chain reaction using the information of the mouse or other mammals. It had been determined that the open reading frame of the porcine APOA5 gene consists of 1092 bp, which encodes a predicted protein composed of 363 amino acids with a similarity to bovine (80.43%) and to human (78.47%). The expression analysis indicated that the porcine APOA5 gene was expressed in hypophysis, fat and liver. Twelve single nucleotide polymorphisms (SNPs), including 4 SNPs in the 5' end, 1 SNP in second intron, 1 SNP in third exon and 6 SNPs in the 3' end, were identified in the porcine APOA5 gene and genotyped on the Jinhua × Pietrain F2 reference population, it had revealed that the SNP of C1834T was significantly associated with average backfat thickness and leaf fat weight (P < 0.01 and P < 0.05, respectively). In conclusion, this study has got basic information of the porcine APOA5 gene and provides evidence that the APOA5 gene could be a potential candidate gene for fat deposition.

[The radioimmunoassay of growth hormone and prolactin and its application].

AIM: To set up a highly specific and sensitive double antibody radioimmunoassay (RIA) for determining the contents of growth hormone (GH) and prolactin (PRL) in pituitary and plasma of rats; To study the effects of acute hypoxia on GH and PRL of rats. METHODS: We use chloramine-T technique iodinate antigen and choose the equilibration and saturated procedure of RIA to add the preparations. RESULTS: Exposed to 7 km-hypoxia for 0.5 h, pituitary GH content increased (P < 0.05) and conversely, plasma GH levels were suppressed (P < 0.05); while the PRL levels in both pituitary and plasma were suppressed (P < 0.01); and there was no significantly difference between 5 km hypoxia groups and control. CONCLUSION: We have successfully established the method of radiolabel and double antibody RIA with highly sensitivity; acute hypoxia (7 km) suppressed the secretion of GH and PRL in rats.