Association of hormone-sensitive lipase (HSL) gene polymorphisms with the intramuscular fat content in two Chinese beef cattle breeds.

Hormone-sensitive lipase (HSL) was considered as an essential enzyme in glucolipid metabolism. It has been proposed to be a lead candidate gene for genetic markers of lipid deposition in livestock. The aim of this study was to identify sequence variants (SVs) of the bovine HSL gene and evaluate the relations to intramuscular fat in two indigenous Chinese beef cattle breeds. Expression analysis by quantitative real-time polymerase chain reactions (qPCR) indicated that expression levels of bovine HSL gene were highest in the perirenal fat and heart within two different age stage (adult and calf), respectively. Five SVs were identified by direct DNA sequencing, which included four missense mutations (g.16563C>T, g.16734G>A, g.16896A>G, g.17388G>T) in exon 8 and a synonymous mutation (g.17402C>T) in exon 9. Population genetic analysis showed that except for g.16563C>T and g.17402C>T, all the other detected SVs strongly affected the bovine intramuscular fat content (P < 0.01 or P < 0.05). The individuals with Hap5/5 diplotypes (CC-GG-GG-GG-CC) was highly significantly associated with intramuscular fat content than the other diplotypes (P < 0.01). The above results suggested that the HSL gene can used as potential candidate markers gene for the beef breed improvement through marker assisted selection in Chinese cattle breeds.

Expression of the SIRT2 gene and its relationship with body size traits in Qinchuan cattle (Bos taurus).

Silent information regulator 2 (SIRT2) is a member of the sirtuin family of class III NAD (nicotinamide adenine dinucleotide)-dependent protein deacetylases and may regulate senescence, metabolism and apoptosis. The aims of this study were to investigate whether the SIRT2 gene could be used as a candidate gene in the breeding of Qinchuan cattle. Real-time polymerase chain reaction (RT-PCR) results showed that among all types of tissue that were analyzed, the highest mRNA expression levels of the gene were found in subcutaneous fat. DNA sequencing of 468 individual Qinchuan cattle identified two novel, single nucleotide polymorphisms (g.19501 C > T and g.19518 C > T) in the 3' untranslated region (3'UTR) of the SIRT2 gene. The frequencies of SNP g.19501 C > T and g.19518 C > T were in Hardy-Weinberg disequilibrium in all the samples (chi-square test, χ2 < χ0.052). An association analysis showed that the two loci were significantly correlated with some body size traits and the H2H2 (-CT-CT-) diplotypes performed better than other combinations. These results indicated that the variations in the SIRT2 gene and their corresponding genotypes may be considered as molecular markers for economic traits in cattle breeding.

Detection of polymorphisms in the bovine leptin receptor gene affects fat deposition in two Chinese beef cattle breeds.

Leptin receptor (LEPR) gene play a pivotal role in the regulation of fat deposition and energy homeostasis. This study investigated the presence and frequency of polymorphisms of bovine LEPR gene and determine whether the polymorphisms are associated with the fat deposition in two Chinese beef cattle breeds. Quantitative real-time polymerase chain reactions identified that the expression of LEPR gene was highest in the liver and subcutaneous fat. Four single nucleotide polymorphisms (SNPs) were identified including g.24169C > T, g.24256T > A, g.24267 G > C and g.24413T > A. A greater backfat thickness was associated with the AA genotype of g.24256T > A compared to the TT genotype. A greater intramuscular fat content was associated with the GG genotype of g.24267 G > C compared to the CC genotype. Both g.24169C > T and g.24413T > A were not correlated with fat deposition. These results indicated that the SNP g.24256T > A and g.24267 G > C of LEPR gene may be useful markers for genetic improvement of fat deposition in Chinese beef cattle breeds.

The genetic polymorphisms of melanocortin-4 receptor gene are associated with carcass quality traits in a Chinese indigenous beef cattle breed.

Melanocortin-4 receptor (MC4R) was considered as an essential modifiers in feelings intake, the regulation of metabolism and body weight. This study aimed at identifying polymorphisms in MC4R gene that might associate with carcass quality traits in Chinese indigenous beef cattle breed. qPCR analysis showed that the MC4R gene was widely expressed in various tissues, with predominantly expression levels in heart. Three single-nucleotide polymorphisms (SNPs) were identified, including a mutation (g.85A > G) in 5'untranslated regions (UTR) and two mutations (g.927C > T and g.1069C > G) in exon 1. Based on the χ2 test, both g.927C > T and g.1069C > G loci fitted with Hardy-Weinberg equilibrium (P > .05). Population genetic analysis showed that except for g.85A > G, the other detected SNPs strongly affected the bovine back fat thickness and intramuscular fat content (P < .05). The individuals with Hap1/4 diplotypes (ACC-ATG) were highly significantly associated with carcass quality traits than the other diplotypes (P < .01 or P < .05). Results indicated that the bovine MC4R gene polymorphisms were implicated as genetic markers of potential importance in marker-assisted selection (MAS) strategies to improve carcass quality in Chinese Qinchuan cattle.

[Effects of nitrogen addition on the structure of rhizosphere microbial community in Pinus tabuliformis plantations on Loess Plateau, China]. / æ°®æ·»åŠ å¯¹é»„åœŸä¸˜é™µåŒºæ²¹æ¾äººå·¥æž—æ ¹é™ åœŸå£¤å¾®ç”Ÿç‰©ç¾¤è½ç»“æž„çš„å½±å“.

Atmospheric nitrogen deposition in China displays a pronounced southeast-northwest gradient, with a range of ～35 kg·hm-2·a-1 in southern and central China and ～7.55 kg·hm-2·a-1 in the northwest. With the Grain for Green project, the environment of Loess Plateau has been greatly improved in the past decades. Little is known about how nitrogen deposition impacts the soil microbial communities in plantations in this region. In order to investigate the responses of diversity and structure of soil microbial community in Pinus tabuliformis plantations to nitrogen addition on Loess Plateau, China, we used high-throughput sequencing of 16S ribosomal RNA genes of bacteria and ITS genes of fungi to investigate the effects of nitrogen addition (200 kg N·hm-2·a-1) on the bacterial and fungal community over a 40-year chronosequence of coniferous P. tabuliformis plantation forests. After nitrogen addition, the Shannon diversity of both bacteria and fungi significantly increased in the 25-year-old stand, while the abundance-based coverage estimator of bacteria increased significantly in the 40-year-old stand. Nitrogen addition enhanced the relative abundance of Bacteroidetes in the 40-year-old stand and that of Acidobacteria/Zygomycota in the 25-year-old stand. In contrast, the relative abundance of Thaumarchaeota was reduced by nitrogen addition in the 40-year old stand. The effects of nitrogen addition were stronger on bacterial than on fungal community structure as indicated by the results from non-metric multidimensional scaling analysis. Moreover, the effects of nitrogen addition were stronger in the 25-year-old stand than in the 40-year-old stand. These results indicated that the effects of nitrogen addition on microbial community structure diminished over time in temperate forests on Loess Plateau, China. The stronger effects of nitrogen addition was found on the community structure of bacteria than that of fungi, and on the microbial community structure in the 25-year-old stand than in the 40-year-old stand. Our findings suggested that forest ecosystem at a certain stage (～40-year old) would be less sensitive to disturbance such as nitrogen addition than young forests.