Histone genes are clustered with a 15-kilobase repeat in the chicken genome.

Histone mRNA isolated from 5-day-old chick embryos has been used as a template for complementary DNA (cDNA) synthesis. The resultant cDNA, after removal of sequences complementary to rRNA, was used to detect histone genes in adult chicken genomal DNA. Hybridisation data indicate that the histone genes are repeated about 10-fold in the chicken genome. Restriction endonuclease analysis reveals some sequence heterogeneity in these genes. However, the results show that chicken histone genes are clustered with a basic repeat unit of 15 kilobases.     

Similarity of the nucleotide sequences of rat alpha-lactalbumin and chicken lysozyme genes

alpha-Lactalbumin (alpha-LA) is a milk protein that interacts with the enzyme galactosyltransferase, modifying its substrate specificity in a way which promotes the transfer of galactose to glucose, resulting in a way which promotes the transfer of galactose to glucose, resulting in a beta-1----4 glycosidic linkage and the synthesis of lactose. Lysozyme, an enzyme which catalyses the hydrolysis of a beta-1----4 glycosidic linkage in polysaccharides, has been shown to be structurally related to alpha-LA and it has been proposed that they have arisen from a common ancestral gene. To compare their evolutionary relationships, we report here the complete nucleotide sequence of the rat alpha-LA gene, including its 5'-flanking sequences, and compare its gene structure with the chicken egg-white lysozyme gene. Both genes contain three introns at similar positions. The first three exons of the two genes have similar nucleotide sequences. The fourth exon of alpha-LA, which partly codes for the C-terminal residues of the protein, essential for its interaction with galactosyltransferase, is markedly different from the corresponding exon of the lysozyme gene and is preceded by two (TG)n repeats.     

Immunodeficiency virus rev trans-activator modulates the expression of the viral regulatory genes

The pathogenic human retrovirus human immunodeficiency virus type 1 (HIV-1) encodes two trans-acting nuclear proteins, tat and rev, whose functional expression is essential for viral replication in vitro. The tat protein greatly enhances the expression of both structural and regulatory genes of HIV-1 (linked to the viral long-terminal-repeat promoter element), whereas the rev gene product (previously termed art or trs) has only been shown to be required for the synthesis of structural proteins. Here, we demonstrate that rev also moderates the expression of regulatory genes of HIV-1. It decreases the expression of messenger RNAs that encode the full-length form of the viral tat gene product or the rev protein itself, and induces the synthesis of a previously unreported, truncated tat protein. These actions of rev are mediated by a dramatic shift in the ratio of spliced to unspliced cytoplasmic HIV-1 mRNA. Therefore rev not only activates the synthesis of the viral structural proteins, but also modulates the level and quality of HIV-1 regulatory gene expression.     

Discovering genes are made of DNA

Maclyn McCarty is the sole surviving member of the team that made the remarkable discovery that DNA is the material of inheritance. This preceded by a decade the discovery of the structure of DNA itself. Here he shares his personal perspective of those times and the impact of the double helix.     

The ovalbumin gene region: common features in the organisation of three genes expressed in chicken oviduct under hormonal control.

Two large DNA fragments overlapping the chicken ovalbumin gene have been isolated by molecular cloning. Analysis of these fragments provided a map of a 46,000-base pair region of the chicken genome. This region contains the complete ovalbumin gene (including its mRNA leader-coding sequence) and at least two other genes of unknown function. All three genes are orientated in the same direction and their expression in chicken oviduct is under hormonal control. The three genes share some sequence homologies, suggesting that duplications have occurred in the ovalbumin gene region in the course of evolution.     

Evolution of type C viral genes: evidence for an Asian origin of man.

Old World monkeys and apes, including man, possess, as a normal component of their cellular DNA, gene sequences (virogenes) related to the RNA of a virus isolated from baboons. A comparison of the viral gene sequences and the other cellular sequences distinguishes those Old World monkeys and apes that have evolved in Africa from those that have evolved in Asia. Among the apes, only gorilla and chimpanzee seem by these criteria to be African, whereas gibbon, orang-utan and man are identified as Asian, leading us to conclude that most of man's evolution has occurred outside Africa.     

ABO genes are differentially distributed in socio-economic groups in England

No direct evidence is available concerning what average genetic differences, if any, characterize the segments of socially stratified human populations, although theoretical considerations suggest that genetic differentiation within such populations is to be expected. We have now analysed two large samples of data from blood donors in England to test whether the distributions of the ABO and Rhesus blood group phenotypes are random with respect to socio-economic groups as determined by occupational classification. We have found that in both native and migrant sections of the populations of two widely separated regions (south-west England and part of Yorkshire) and in both sexes, the A phenotype is highly significantly more, and the O phenotype significantly less, frequent than expected in social classes I and II, while the converse is seen in social classes III-V. An individual of the A phenotype has thus about 15% greater probability than chance would dictate of being placed in classes I and II. The distribution of the Rh+ and Rh- phenotypes does not differ significantly between classes. It seems unlikely that this nonrandom distribution of the ABO phenotypes among socio-economic groups results from sampling, historical or migrational effects and we conclude that the observed association is likely to result from pleiotropic effects of the ABO alleles (or genes closely linked to them) on attributes influencing occupational type, social mobility and social class.     

Linkage of regression and malignant conversion of rabbit viral papillomas to MHC class II genes.

Human papillomaviruses associated with cutaneous and anogenital cancers induce intraepithelial precursor lesions which may regress spontaneously or progress into invasive carcinomas. Cell-mediated immune responses are probably involved in regression of precancerous lesions and the polymorphism of the genes responsible may thus have a key role in the variability of the host response. Skin warts and cancers induced in rabbits by Shope papillomavirus provide a model to test this hypothesis. We analysed a restriction-fragment-length polymorphism of major histocompatibility complex class I and class II genes and T-cell receptor beta-chain genes in infected domestic rabbits. We found a strong linkage between wart regression and a DR alpha EcoRI fragment, and an increased relative risk of malignant transformation associated with a DQ alpha PvuII fragment. This indicates a genetic control of wart evolution, involving genes in the class II region of the major histocompatibility complex.     

FADS2对鸡前脂肪细胞脂肪酸代谢相关基因表达的影响

脂肪酸的含量及比例对改善鸡肉品质和风味起着重要作用,因此探究调控脂肪酸代谢的关键基因和作用机制能够为改善鸡肉品质提供新的科学依据。基于前期RNA-seq结果,确定脂肪酸脱氢酶2(FADS2)为影响鸡不饱和脂肪酸比率的关键基因。文章构建FADS2基因RNA干扰慢病毒表达载体,转染鸡前脂肪细胞并鉴定干扰效率,筛选出有效干扰片段并进行正式试验,通过设置阴性对照组,转录组测序检测相关基因表达。结果表明,190个基因显著差异性表达,其中65个基因下调,125个基因上调。通过比较基因组学和基因功能分析,鉴定出STAT1、LY86、FABP5、OGFR、ACTA1、SLC5A6、NCOA7、KLF2、KLF4、ACSL5和FABP3基因可能是FADS2基因影响脂肪酸代谢的相关下游基因,为深入研究脂肪酸代谢过程提供一定的理论基础。