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

Effect of Mulberry Leaf TMR on Growth Performance, Meat Quality and Expression of Meat Quality Master Genes (ADSL, H-FABP) in Crossbred Black Goats

This study was conducted to examine the effect of a mulberry leaf total mixed ration (TMR) diet on growth performance, apparent digestibility, meat quality and the expression of related meat-quality genes (ADSL, H-FABP) in crossbred black goats. Forty-four Guizhou crossbred black goats (Nubian black goat ♂ × Guizhou black goat ♀), weighing 33.43 ± 0.55 kg, were chosen. The goats were randomly divided into four groups, with 11 test replicates in each group. Group I was the control group and fed with the traditional feeding method of roughage and concentrate supplement without adding mulberry leaf. Group II was fed with a 40% mulberry leaf pellet TMR diet. Group III was fed with a freshly processed 40% mulberry leaf TMR diet. Group IV was fed with a 40% mulberry leaf fermented total mixed rations (FTMR) diet. The results showed that the average daily gain (ADG) of group II was significantly higher than that of group I and III (p < 0.05). The apparent digestibility of group II of ether extract (EE) and neutral detergent fiber (NDF) was significantly higher than that of group I (p < 0.05), and the apparent digestibility of dry matter (DM) and crude protein (CP) was significantly higher than that of group I (p < 0.01). Compared with group I, meat in group II had lower meat color lightness (L*) and yellowness (b*) values (p < 0.01) in the Longissimus thoracis et lumborum. The shear force of group II was significantly lower than that of group I (p < 0.05). The total fatty acids (TFA) of group II was significantly higher than that of groups I and III (p < 0.05), but the total saturated fatty acids (SFA) of group II was significantly lower that than of group I (p < 0.01). Subsequently, the Unsaturated fatty acids (USFA), Monounsaturated fatty acids (MUFA), and Polyunsaturated fatty acids (PUFA) of group II were significantly higher than those in group I (p < 0.01). The contents of total amino acids (TAA), total essential amino acids (EAA), total non-essential amino acids (NEAA) and total of major fresh-tasting amino acids (DAA) of groups II, III and IV were significantly higher than those of group I (p < 0.05), as well as the contents of IMP (p < 0.01). The expression of the H-FABP gene in the arm triceps of group II was significantly higher than that of groups I, III and IV (p < 0.05). The expression of the ADSL gene in the Longissimus thoracis et lumborum and biceps femoris of group II was significantly higher than that of group I (p < 0.05). Collectively, the results of the current study indicated that the mulberry leaf TMR diet improved the growth performance, apparent digestibility and expression of related meat-quality master genes (ADSL, H-FABP) in crossbred black goats, which promoted the deposition of intramuscular fat (IMF) and inosinic acid (IMP) and improved the composition of fatty acids and amino acids in the muscles.

Expression of DGAT2 Gene and Its Associations With Intramuscular Fat Content and Breast Muscle Fiber Characteristics in Domestic Pigeons (Columba livia)

Diacylglycerol acyltransferase 2 (DGAT2) catalyzes the final step in triglyceride synthesis and plays an important role in the synthesis of fat, but the effects of its expression on intramuscular fat (IMF) content and muscle development are still unknown. In this study, we investigated the expression of the DGAT2 gene and its associations with IMF content and breast muscle fiber characteristics in pigeons. The spatiotemporal expression profile of the pigeon DGAT2 gene in breast muscle showed that the mRNA expression level of DGAT2 gene in subcutaneous fat was the highest (p < 0.01) among eight tissues from 0 to 4 weeks of age, and showed an upward trend week by week, followed by liver (p < 0.05). Moreover, both mRNA and protein levels of the DGAT2 gene in breast muscle showed an upward trend from 0 to 4 weeks (p < 0.05), accompanied by the upregulation of MYOD1 and MSTN. In addition, the paraffin section analysis results revealed that the diameter and cross-sectional area of pectoralis muscle fiber significantly increased with age (p < 0.05), and a significant positive correlation was shown between the DGAT2 gene expression level and muscle fiber diameter (p < 0.05). Furthermore, correlation analysis suggested that the mRNA expression level of the pigeon DGAT2 gene was significantly (p < 0.01) correlated with IMF content in breast muscle. These results imply that the DGAT2 gene has a close relationship with IMF content and breast muscle fiber characteristics in pigeons, indicating that the DGAT2 gene might be used as a candidate gene marker-assisted breeding in pigeons.

Comparative Genome and Transcriptome Integration Studies Reveal the Mechanism of Pectoral Muscle Development and Function in Pigeons

Pigeon breed resources provide a genetic model for the study of phenomics. The pectoral muscles play a key role for the meat production performance of the meat pigeon and the athletic ability of the High flyers. Euro-pigeons and Silver King pigeons are commercial varieties that exhibit good meat production performance. In contrast to the domestication direction of meat pigeons, the traditional Chinese ornamental pigeon breed, High flyers, has a small and light body. Here, we investigate the molecular mechanism of the pectoral muscle development and function of pigeons using whole-genome and RNA sequencing data. The selective sweep analysis (F_ST and log2 (θπ ratio)) revealed 293 and 403 positive selection genes in Euro-pigeons and Silver King, respectively, of which 65 genes were shared. With the Silver King and Euro-pigeon as the control group, the High flyers were selected for 427 and 566 genes respectively. There were 673 differentially expressed genes in the breast muscle transcriptome between the commercial meat pigeons and ornamental pigeons. Pigeon genome selection signal combined with the breast muscle transcriptome revealed that six genes (SLC16A10, S100B, SYNE1, HECW2, CASQ2 and LOC110363470) from commercial varieties of pigeons and five genes (INSC, CALCB, ZBTB21, B2M and LOC110356506) from Chinese traditional ornamental pigeons were positively selected which were involved in pathways related to muscle development and function. This study provides new insights into the selection of different directions and the genetic mechanism related to muscle development in pigeons.

Development and Validation of KASP Assays for the Genotyping of Racing Performance-Associated Single Nucleotide Polymorphisms in Pigeons

Pigeon racing's recent upturn in popularity can be attributed in part to the huge prize money involved in these competitions. As such, methods to select pigeons with desirable genetic characteristics for racing or for selective breeding have also been gaining more interest. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for genotyping-specific genes is one of the most commonly used molecular techniques, which can be costly, laborious and time consuming. The present study reports the development of an alternative genotyping method that employs Kompetitive Allele Specific Polymerase Chain Reaction (KASP) technology with specifically designed primers to detect previously reported racing performance-associated polymorphisms within the LDHA, MTYCB, and DRD4 genes. To validate, KASP assays and PCR-RFLP assays results from 107 samples genotyped for each of the genes were compared and the results showed perfect (100%) agreement of both methods. The developed KASP assays present an alternative rapid, reliable, and cost-effective method to identify polymorphisms in pigeons.

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.

Investigation of the CEBPA gene expression pattern and association analysis of its polymorphisms with meat quality traits in chickens

Meat quality is closely related to the fat deposition which is regulated by a cascade of transcription factors. As a transcription factor, the CCAAT/enhancer binding protein alpha (CEBPA) is considered as one of the key molecules regulating adipogenesis. Therefore, the objective of this study was to detect the expression pattern of the CEBPA gene and evaluate whether its single nucleotide polymorphisms (SNPs) were associated with the meat quality traits in Wuliang Mountain Black-bone (WLMB) chickens. The results showed that the chicken CEBPA mRNA was widely expressed in the 11 tissues, and the expression pattern of it might be tissue- and time-specific different. The locus of g.74C > G was not significantly associated with chicken meat quality. For the locus of g.552G > A, chickens with the GG genotype showed higher pH (p < 0.01), lower drip loss (p < 0.01) and higher intramuscular fat (p < 0.05) than those with other genotypes. It suggested that polymorphisms of the CEBPA gene were significantly associated with the meat quality traits of WLMB chickens. The results of this study contribute to the functional research of the CEBPA gene and lay the foundation for improving meat quality based on the marker-assisted selection in chickens.

The temporal-spatial patterns, polymorphisms and association analysis with meat quality traits of FABP1 gene in domestic pigeons (Columba livia)

1. Fatty acid-binding proteins (FABP) are members of lipid-binding proteins, which participate in the metabolism and intracellular transportation of lipids. This study was designed to investigate the expression patterns, polymorphisms and associations with meat quality traits of the FABP1 gene in pigeons. 2. The temporal-spatial expression patterns showed FABP1 was widely expressed in all eleven tissues from 0-4 weeks of age, the expression level in the liver was the highest, followed by the small intestine and subcutaneous fat. 3. Five novel SNPs were found; all of them were synonymous and in Hardy-Weinberg equilibrium. Association analysis revealed that for the SNP of G161C, the AB and BB genotypes had higher (P ≤ 0.01) inosinic acid concentrations in breast muscle than the AA genotype. The BB genotype showed the highest (P < 0.01) intramuscular fat among the three genotypes, and significantly greater FABP1 mRNA levels were observed in the breast muscle of the BB genotype than in the AA and AB genotypes (P < 0.01). In the SNP C1376T, the AB and BB genotypes showed higher (P < 0.01) intramuscular fat than the AA genotype, and the relative mRNA expression level of the BB (P < 0.01) and AB (P < 0.05) genotypes was higher than that of the AA genotype in breast muscle. Correlation analysis implied that the FABP1 mRNA expression level was closely related to the inosinic acid (P < 0.05) and intramuscular fat content (P < 0.01). Oil red O staining of frozen sections of breast muscle on d 28 for SNPs G161C and C1376T also indicated that the BB genotype had the highest intramuscular fat content in both SNPs. In addition, correlation analysis implied the FABP1 mRNA expression level was closely related to inosinic acid (P < 0.05) and intramuscular fat content (P < 0.01). 4. The results suggested that FABP1 could be a potential candidate gene in marker-assisted selection for breeding pigeons with high-quality meat.