Linsheng Gui

An Optimized Trichloroacetic Acid/Acetone Precipitation Method for Two-Dimensional Gel Electrophoresis Analysis of Qinchuan Cattle Longissimus Dorsi Muscle Containing High Proportion of Marbling

Longissimus dorsi muscle (LD) proteomics provides a novel opportunity to reveal the molecular mechanism behind intramuscular fat deposition. Unfortunately, the vast amounts of lipids and nucleic acids in this tissue hampered LD proteomics analysis. Trichloroacetic acid (TCA)/acetone precipitation is a widely used method to remove contaminants from protein samples. However, the high speed centrifugation employed in this method produces hard precipitates, which restrict contaminant elimination and protein re-dissolution. To address the problem, the centrifugation precipitates were first grinded with a glass tissue grinder and then washed with 90% acetone (TCA/acetone-G-W) in the present study. According to our result, the treatment for solid precipitate facilitated non-protein contaminant removal and protein re-dissolution, ultimately improving two-dimensional gel electrophoresis (2-DE) analysis. Additionally, we also evaluated the effect of sample drying on 2-DE profile as well as protein yield. It was found that 30 min air-drying did not result in significant protein loss, but reduced horizontal streaking and smearing on 2-DE gel compared to 10 min. In summary, we developed an optimized TCA/acetone precipitation method for protein extraction of LD, in which the modifications improved the effectiveness of TCA/acetone method.

NRF1 and ZSCAN10 bind to the promoter region of the SIX1 gene and their effects body measurements in Qinchuan cattle

The SIX1 homeobox gene belongs to the six homeodomain family and is widely thought to play a principal role in mediating of skeletal muscle development. In the present study, we determined that the bovine SIX1 gene was highly expressed in the longissimus thoracis and physiologically immature individuals. DNA sequencing of 428 individual Qinchuan cattle identified nine single nucleotide polymorphisms (SNPs) in the promoter region of the SIX1 gene. Using a series of 5′ deletion promoter plasmid luciferase reporter assays and 5′-rapid amplification of cDNA end analysis (RACE), two of these SNPs were found to be located in the proximal minimal promoter region −216/−28 relative to the transcriptional start site (TSS). Correlation analysis showed the combined haplotypes H1-H2 (-GG-GA-) was significantly greater in the body measurement traits (BMTs) than the others, which was consistent with the results showing that the transcriptional activity of Hap2 was higher than the others in Qinchuan cattle myoblast cells. Furthermore, the electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation assay (ChIP) demonstrated that NRF1 and ZSCAN10 binding occurred in the promoter region of diplotypes H1-H2 to regulate SIX1 transcriptional activity. This information may be useful for molecular marker-assisted selection (MAS) in cattle breeding.

Genetic Architecture and Selection of Chinese Cattle Revealed by Whole Genome Resequencing

&NA; The bovine genetic resources in China are diverse, but their value and potential are yet to be discovered. To determine the genetic diversity and population structure of Chinese cattle, we analyzed the whole genomes of 46 cattle from six phenotypically and geographically representative Chinese cattle breeds, together with 18 Red Angus cattle genomes, 11 Japanese black cattle genomes and taurine and indicine genomes available from previous studies. Our results showed that Chinese cattle originated from hybridization between Bos taurus and Bos indicus. Moreover, we found that the level of genetic variation in Chinese cattle depends upon the degree of indicine content. We also discovered many potential selective sweep regions associated with domestication related to breed‐specific characteristics, with selective sweep regions including genes associated with coat color (ERCC2, MC1R, ZBTB17, and MAP2K1), dairy traits (NCAPG, MAPK7, FST, ITFG1, SETMAR, PAG1, CSN3, and RPL37A), and meat production/quality traits (such as BBS2, R3HDM1, IGFBP2, IGFBP5, MYH9, MYH4, and MC5R). These findings substantially expand the catalogue of genetic variants in cattle and reveal new insights into the evolutionary history and domestication traits of Chinese cattle.

Genetic variants in SIRT3 transcriptional regulatory region affect promoter activity and fat deposition in three cattle breeds

Sirtuin 3 (SIRT3) is a mitochondrial nicotinamide adenine dinucleotide (NAD)-dependent deacetylase. It has crucial roles in regulating the respiratory chain, in adenosine triphosphate (ATP) production, and in both the citric acid and urea cycles. The aim of this study was to investigate whether SIRT3 could be used as a candidate gene in the breeding of cattle. Expression analysis by quantitative real-time polymerase chain reactions (qPCR) indicated that expression levels of SIRT3 were highest in the kidney, rumen, liver, omasum and muscle. Using sequencing technology on a total of 913 cattle representing three indigenous Chinese beef cattle breeds, three single nucleotide polymorphisms (SNPs) were identified in the promoter region of SIRT3, and five haplotypes representing five potential transcription factor compositions of polymorphic potential cis-acting elements. Association analysis indicated that the Hap3/8 diplotype performed better than other combinations in intramuscular fat content. In addition, the promoter activity with Hap1 haplotype was higher than the Hap8 haplotype, consistent with the association analysis. The results indicate that the polymorphisms in transcription factor binding sites of SIRT3 promoter may affect the transcriptional activity of SIRT3, and thus alter intramuscular fat content in beef cattle.

Association between FASN gene polymorphisms ultrasound carcass traits and intramuscular fat in Qinchuan cattle

Fatty acid synthase (FASN) is an enzyme involved with fat deposition and fatty acid composition in cattle. This study was conducted to detect single nucleotide polymorphisms (SNPs) of the FASN gene and explore their relationships with ultrasound carcass traits in order to assess the potential use of the FASN gene for the breeding selection of Qinchuan cattle for desirable carcass traits. The frequencies of SNP g.12740C>T, g.13192T>C and g.13232C>T were identified in 525 individual Qinchuan cattle which were also assessed for backfat depth, eye muscle area and intramuscular fat by ultrasound. According to the PIC values, g.13192T>C possessed an intermediate polymorphism (0.25<PIC<0.5). The SNPs of g.13232C>T, g.12740C>T possessed low polymorphism (PIC<0.25). Chi-square tests showed that g.13192T>C were in Hardy-Weinberg disequilibrium (c2<c0.052). Two SNPs were found to be associated with variation in ultrasound carcass traits. The H2H2 diplotypes had a greater back fat depth than H1H1, H1H4 and H1H2 (P<0.01). The TT genotype at g.13192T>C was associated with a greater eye muscle area and the TT genotype at g.13232C>T was associated with greater intramuscular fat. When these genotypes were combined there was no difference in eye muscle area and intramuscular fat between the diplotypes. The H2H2 diplotype was associated with carcass traits that are likely to provide economic advantage in Qinchuan cattle. Variations in the FASN genes and their corresponding genotypes may be considered as molecular markers for economic traits in cattle breeding.

Characterization of the promoter region of the bovine SIX1 gene: Roles of MyoD, PAX7, CREB and MyoG

The SIX1 gene belongs to the family of six homeodomain transcription factors (TFs), that regulates the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and mediate skeletal muscle growth and regeneration. Previous studies have demonstrated that SIX1 is positively correlated with body measurement traits (BMTs). However, the transcriptional regulation of SIX1 remains unclear. In the present study, we determined that bovine SIX1 was highly expressed in the longissimus thoracis. To elucidate the molecular mechanisms involved in bovine SIX1 regulation, 2-kb of the 5′ regulatory region were obtained. Sequence analysis identified neither a consensus TATA box nor a CCAAT box in the 5′ flanking region of bovine SIX1. However, a CpG island was predicted in the region −235 to +658 relative to the transcriptional start site (TSS). An electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay in combination with serial deletion constructs of the 5′ flanking region, site-directed mutation and siRNA interference demonstrated that MyoD, PAX7 and CREB binding occur in region −689/−40 and play important roles in bovine SIX1 transcription. In addition, MyoG drives SIX1 transcription indirectly via the MEF3 motif. Taken together these interactions suggest a key functional role for SIX1 in mediating skeletal muscle growth in cattle.

Molecular Characterization of Bovine SMO Gene and Effects of Its Genetic Variations on Body Size Traits in Qinchuan Cattle (Bos taurus).

Smoothened (Smo)-mediated Hedgehog (Hh) signaling pathway governs the patterning, morphogenesis and growth of many different regions within animal body plans. This study evaluated the effects of genetic variations of the bovine SMO gene on economically important body size traits in Chinese Qinchuan cattle. Altogether, eight single nucleotide polymorphisms (SNPs: 1–8) were identified and genotyped via direct sequencing covering most of the coding region and 3ʹUTR of the bovine SMO gene. Both the p.698Ser.>Ser. synonymous mutation resulted from SNP1 and the p.700Ser.>Pro. non-synonymous mutation caused by SNP2 mapped to the intracellular C-terminal tail of bovine Smo protein; the other six SNPs were non-coding variants located in the 3ʹUTR. The linkage disequilibrium was analyzed, and five haplotypes were discovered in 520 Qinchuan cattle. Association analyses showed that SNP2, SNP3/5, SNP4 and SNP6/7 were significantly associated with some body size traits (p < 0.05) except SNP1/8 (p > 0.05). Meanwhile, cattle with wild-type combined haplotype Hap1/Hap1 had significantly (p < 0.05) greater body length than those with Hap2/Hap2. Our results indicate that variations in the SMO gene could affect body size traits of Qinchuan cattle, and the wild-type haplotype Hap1 together with the wild-type alleles of these detected SNPs in the SMO gene could be used to breed cattle with superior body size traits. Therefore, our results could be helpful for marker-assisted selection in beef cattle breeding programs.

MicroRNA-214 regulates immunity-related genes in bovine mammary epithelial cells by targeting NFATc3 and TRAF3

In human, microRNA-214 (miR-214) plays crucial roles in mechanisms of immunity. However, the potential importance of miR-214 in immune mechanisms in dairy cows has not been investigated. In this study, we assessed potential immunity-related functions of miR-214 in human 293A cells and in bovine mammary epithelial cells (BMECs). We found that NFATc3 and TRAF3 could be targeted by miR-214 in both 293A cells and BMECs. We also found that miR-214 indirectly inhibited the expression of MAP3K14, TBK1 and inflammatory cytokines IL-6 and IL-1β. Taken together, our data revealed miR-214 regulated immunity-related genes by targeting NFATc3 and TRAF3, which provides insight into the molecular basis of immunity.

Profile of muscle tissue gene expression specific to water buffalo: Comparison with domestic cattle by genome array

In contrast with the past, the water buffalo is now not only a draft animal, but also an important food source of milk and meat. It is increasingly apparent that the water buffalo have huge potential for meat production, but its breeding needs to be investigated. Regarding the molecular mechanisms involved in the meat quality difference between the buffalo (Bubalus bulabis) and yellow cattle (Bos taurus), 12 chemical-physical characteristics related to the meat quality of longissimus thoracis muscles (LTM) have been compared at the age of 36 months. Intramuscular lipid and b* (yellowness) were greater in cattle than the buffalo, whereas a* (redness) was greater in the buffalo. Gene expression profiles were constructed by bovine genome array. A total of 8884 and 10,960 probes were detected in buffalo and cattle, respectively, with 1580 genes being differentially expressed. Over 400 probes were upregulated and nearly 1200 were downregulated in LTM of the buffalo, most being involved in ribosomal RNA (rRNA) processing, cholesterol homeostasis, regulation of transcription, response to hypoxia, and glycolysis. Quantitative real-time PCR was used to validate the microarray data. Enriched GO analyses of highly expressed genes in LTM showed that protein biosynthesis, striated muscle contraction, iron homeostasis, iron transport, glycolysis and glucose metabolism were similar between the buffalo and cattle. High protein content, low fat content and deep meat color of buffalo LTM may be closely associated with the increased expression of genes involved in cholesterol and iron homeostasis, while also reducing the expression of genes involved in ubiquitin-mediated proteolysis and protein oxidative phosphorylation. These results establish the groundwork for further studies on buffalo meat quality and will be beneficial in improving water buffalo breeding by molecular biotechnology.

Polymorphism in promoter of SIX4 gene shows association with its transcription and body measurement traits in Qinchuan cattle

The sine oculis homeobox homolog 4 (SIX4) gene belongs to the SIX gene family, which plays a critical role in muscle regeneration and early stages of ontogeny. This study aimed to detect promoter variations of bovine SIX4 genes in Qinchuan cattle, and to evaluate the effect of transcription regulations and body measurement traits. Quantitative real-time PCR (qPCR) results showed that the mRNA expression levels of SIX4 gene were found significantly highest in longissimus thoracis tissue and individual before attaining the stage of physiological maturity. Using sequencing technology on a total of 428 Qinchuan cattle, seven single nucleotide polymorphisms (SNPs) were identified in the promoter region of SIX4, and seven haplotypes representing 18 potential transcription factor compositions of polymorphic potential cis-acting elements. Association analysis indicated that the H3-H3 diplotype performed greater withers height, chest depth, chest circumference, back fat thickness and ultrasound loin muscle area (P < 0.05) than H5-H6, which were consistent with the promoter activity of Hap3 haplotype was higher than the Hap5 and Hap6 haplotype in vitro. These potential transcription factor information and combined genotypes H3-H3 of the SIX4 gene can be used as a molecular marker for selection of economic traits in Qinchuan cattle.