Determination of Residual Feed Intake and Its Associations with Single Nucleotide Polymorphism in Chickens

Marker assisted selection （MAS） for residual feed intake （RFI） is considered to be one of the powerful means to improve feed conversion efficiency, and therefore reduce production costs. To test the inner relationship among body compositions, growth traits and RFI, four models were proposed to assess the extensively explanatory variables accounting for partial variables in feed intake besides metabolic body weight and growth rate. As a result, the original model （Koch＇s model） had the lowest R2 （80.78%） and the highest Bayesian information criterion （1 323.3） value among the four models. Moreover, the effects on RFI caused by single nucleotide polymorphisms （SNPs） were assessed in this study. Twelve SNPs from 7 candidate genes were genotyped in 2 Chinese native strains, rs14743490 of RPLP2 gene showed suggestively significant association with initial body weight in both strains （P〈0.10）. rs15047274 of TAF15 was significantly associated with growth weight, final weight, and feed intake （P〈0.05） in N301 strain, in contrast, it was only suggestively significant associated with feed intake （P〈0.10） in N414 strain, rs15869967 was significantly associated with RFI in N414 strain but not in N301 strain. This study has identified potential genetic markers suitable for MAS in improving the above mentioned traits, but these associations need to be rectified in other larger populations in future.

Advances on genetic and genomic studies of ALV resistance

Avian leukosis(AL)is a general term for a variety of neoplastic diseases in avian caused by avian leukosis virus(ALV).No vaccine or drug is currently available for the disease.Therefore,the disease can result in severe economic losses in poultry flocks.Increasing the resistance of poultry to ALV may be one effective strategy.In this review,we provide an overview of the roles of genes associated with ALV infection in the poultry genome,including endogenous retroviruses,virus receptors,interferon-stimulated genes,and other immune-related genes.Furthermore,some methods and techniques that can improve ALV resistance in poultry are discussed.The objectives are willing to provide some valuable references for disease resistance breeding in poultry.

High expression of BCL6 inhibits the differentiation and development of hematopoietic stem cells and affects the growth and development of chickens

Background:B-cell CLL/lymphoma 6(BCL6)is a transcriptional master regulator that represses more than 1200 potential target genes.Our previous study showed that a decline in blood production in runting and stunting syndrome(RSS)affected sex-linked dwarf(SLD)chickens compared to SLD chickens.However,the association between BCL6 gene and hematopoietic function remains unknown in chickens.Methods:In this study,we used RSS affected SLD(RSS-SLD)chickens,SLD chickens and normal chickens as research object and overexpression of BCL6 in hematopoietic stem cells(HSCs),to investigate the effect of the BCL6 on differentiation and development of HSCs.Results:The results showed that comparison of RSS-SLD chickens with SLD chickens,the BCL6 was highly expressed in RSS-SLD chickens bone marrow.The bone marrow of RSS-SLD chickens was exhausted and red bone marrow was largely replaced by yellow bone marrow,bone density was reduced,and the levels of immature erythrocytes in peripheral blood were increased.At the same time,the hematopoietic function of HSCs decreased in RSS-SLD chickens,which was manifested by a decrease in the hematopoietic growth factors(HGFs)EPO,SCF,TPO,and IL-3,as well as hemoglobinα1 and hemoglobinβexpression.Moreover,mitochondrial function in the HSCs of RSS-SLD chickens was damaged,including an increase in ROS production,decrease in ATP concentration,and decrease in mitochondrial membrane potential(ΔΨm).The same results were also observed in SLD chickens compared with normal chickens;however,the symptoms were more serious in RSS-SLD chickens.Additionally,after overexpression of the BCL6 in primary HSCs,the secretion of HGFs(EPO,SCF,TPO and IL-3)was inhibited and the expression of hemoglobinα1 and hemoglobinβwas decreased.However,cell proliferation was accelerated,apoptosis was inhibited,and the HSCs entered a cancerous state.The function of mitochondria was also abnormal,ROS production was decreased,and ATP concentration andΔΨm were increased,which was related to the inhibition of apoptosis of stem cells.Conclusions:Taken together,we conclude that the high expression of BCL6 inhibits the differentiation and development of HSCs by affecting mitochondrial function,resulting in impaired growth and development of chickens.Moreover,the abnormal expression of BCL6 might be a cause of the clinical manifestations of chicken comb,pale skin,stunted growth and development,and the tendency to appear RSS in SLD chickens.

DNA methylation in poultry:a review

As an important epigenetic modification,DNA methylation is involved in many biological processes such as animal cell differentiation,embryonic development,genomic imprinting and sex chromosome inactivation.As DNA methylation sequencing becomes more sophisticated,it becomes possible to use it to solve more zoological problems.This paper reviews the characteristics of DNA methylation,with emphasis on the research and application of DNA methylation in poultry.

The SNPs C.513A>T in the MHC B-F gene and rs15001532 in the SPOCK1 gene are associated with Salmonella pullorum disease resistance in chickens

supported by the Earmarked Fund for the Modern Agroindustry Technology Research System, China （CARS-41）;the National High Technology Research and Development Program of China （2011AA100301）

An efficient and rapid method to detect and verify natural antisense transcripts of animal genes

High-throughput sequencing has identified a large number of sense-antisense transcriptional pairs, which indicates that these genes were transcribed from both directions. Recent reports have demonstrated that many antisense RNAs, especially lnc RNA（long non-coding RNA）, can interact with the sense RNA by forming an RNA duplex. Many methods, such as RNA-sequencing, Northern blotting, RNase protection assays and strand-specific PCR, can be used to detect the antisense transcript and gene transcriptional orientation. However, the applications of these methods have been constrained, to some extent, because of the high cost, difficult operation or inaccuracy, especially regarding the analysis of substantial amounts of data. Thus, we developed an easy method to detect and validate these complicated RNAs. We primarily took advantage of the strand specificity of RT-PCR and the single-strand specificity of S1 endonuclease to analyze sense and antisense transcripts. Four known genes, including mouse β-actin and Tsix（Xist antisense RNA）, chicken LXN（latexin） and GFM1（Gelongation factor, mitochondrial 1）, were used to establish the method. These four genes were well studied and transcribed from positive strand, negative strand or both strands of DNA, respectively, which represented all possible cases. The results indicated that the method can easily distinguish sense, antisense and sense-antisense transcriptional pairs. In addition, it can be used to verify the results of high-throughput sequencing, as well as to analyze the regulatory mechanisms between RNAs. This method can improve the accuracy of detection and can be mainly used in analyzing single gene and was low cost.

The genetic regulation of skeletal muscle development:insights from chicken studies

Skeletal muscle development is a complex multi-process trait regulated by various genetic factors.The chicken embryo is an ideal model system for studying skeletal muscle development. However, only a small proportion of the genetic factors affecting skeletal muscle development have been identified in chicken. The aim of this review is to summarize recent knowledge about the genetic factors involved in the regulation of skeletal muscle development in the chicken, such as gene polymorphisms, epigenetic modification, noncoding RNAs and transcription factors, which can influence skeletal muscle development at the genome, epigenome,transcriptome and proteome levels. Research on the regulation of skeletal muscle development in chicken is not yet comprehensive and most of the candidate genes and single nucleotide polymorphisms related to chicken muscle growth remain to be verified in experimental studies. In addition, the data derived from transcriptome sequencing and genome-wide association studies still require further investigation and analysis and comprehensive studies on the regulation of chicken skeletal muscle development will continue as a major research focus.

MicroRNAs Involved in Skeletal Muscle Differentiation

MicroRNAs （miRNAs） negatively regulate gene expression by promoting degradation of target mRNAs or inhibiting their translation. Previous studies have expanded our understanding that miRNAs play an important role in myogenesis and have a big impact on muscle mass, muscle fiber type and muscle-related diseases. The muscle-specific miRNAs, miR-206, miR-1 and miR-133, are among the most studied and best characterized miRNAs in skeletal muscle differentiation. They have a profound influence on multiple muscle differ- entiation processes, such as alternative splicing, DNA synthesis, and cell apoptosis. Many non-muscle-specific miRNAs are also required for the differentiation of muscle through interaction with myogenic factors. Studying the regulatory mechanisms of these miRNAs in muscle differentiation will extend our knowledge of miRNAs in muscle biology and will improve our understanding of the myogenesis regulation.