Polyadenylic acid in Visna virus RNA

Visna virus 70S RNA contains long stretches of polyadenylic acid [poly(A)]. The homogeneity in length of poly(4) regions is observed in 70S RNA from visna virus and all RNA tumor viruses tested, and not with other types of RNA. By this criterion visna virus resembles RNA tumor viruses.     

Polyadenylic acid sequences in the virion RNA of poliovirus and Eastern Equine Encephalitis virus

Poliovirus virion RNA contains a single covalently bound sequence of polyadenylic acid which is approximately 49 nucleotides long. A single, slightly longer polyadenylic acid sequence is contained in Eastern Equine Encephalitis virus RNA. Since these viruses are otherwise dissimilar these sequences may play a common role in viral replication, possibly in translation of the viral RNA.     

Neuroblastoma: drug-induced differentiation increases proportion of cytoplasmic RNA that contains polyadenylic acid

The production of cytoplasmic RNA that contains polyadenylic acid is increased, relative to total cytoplasmic RNA, in a neuroblastoma clone, NBE-(A), after induction of differentiation by 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone, an inhibitor of adenosine 3',5'-monophosphate phosphodiesterase. The amount of RNA that contains polyadenylic acid in cytoplasm may be greater in such differentiated neuroblastoma cells than in proliferating control cells.     

Compatibility with killer explains the rise of RNAi-deficient fungi

The RNA interference (RNAi) pathway is found in most eukaryotic lineages but curiously is absent in others, including that of Saccharomyces cerevisiae. We show that reconstituting RNAi in S. cerevisiae causes loss of a beneficial double-stranded RNA virus known as killer virus. Incompatibility between RNAi and killer viruses extends to other fungal species in that RNAi is absent in all species known to possess double-stranded RNA killer viruses, whereas killer viruses are absent in closely related species that retained RNAi. Thus, the advantage imparted by acquiring and retaining killer viruses explains the persistence of RNAi-deficient species during fungal evolution.     

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.     

Human sarcomas contain RNA related to the RNA of a mouse leukemia virus

Labeled DNA complementary to the RNA of the Rauscher leukemia virus was hybridized with RNA from the polysome fraction of human sarcomas. Eighteen out of 25 specimens contained RNA possessing homology to the RNA of the mouse leukemia virus but not to that of the unrelated viruses causing mammary tumors in mice or myeloblastosis in chickens. Further, no normal adult or fetal tissues showed significant amounts of RNA specific to mouse leukemia virus. It appears that human sarcomas contain RNA sequences homologous to those found in an agent related to a virus known to cause sarcomas in mice.     

Triple-stranded polynucleotide helix containing only purine bases

The structure of the complex involving one polyadenylic acid and two polyinosinic acid chains has been determined by x-ray diffraction. The three coaxial, helical chains have conformations like conventional RNA double helices despite the absence of purine-pyrimidine pairing. Formation of hypoxanthine pairs in codon-anticodon interactions therefore requires only trivial changes in the conformation of a standard nucleotide. Evolution of the contemporary genetic code involving purine-pyrimidine complementarity from a primeval code with only adenine-hypoxanthine pairing would have been possible without major discontinuities in molecular geometry.     

HTLV x-gene product: requirement for the env methionine initiation codon

The human T-cell leukemia viruses (HTLV) are replication-competent retroviruses whose genomes contain gag, pol, and env genes as well as a fourth gene, termed x, which is believed to be the transforming gene of HTLV. The product of the x gene is now shown to be encoded by a 2.1-kilobase messenger RNA derived by splicing of at least two introns. By means of S1 nuclease mapping of this RNA and nucleic acid sequence analysis of a complementary DNA clone, the complete primary structure of the x-gene product has been determined. It is encoded by sequences containing the env initiation codon and one nucleotide of the next codon spliced to the major open reading frame of the HTLV-I and HTLV-II x gene.     

Spontaneous tranformation of human brain cells grown in vitro and description of associated viurs particles

A human brain cell culture grown in vitro has spontaneously transformed, as determined by morphology, growth characteristics, and karyotype analysis. Virus particles morphologically akin to oncogenic RNA viruses are present in the transformed cells, which are now in subculture 60.     

驴乳的化学成分和营养价值

驴乳含水分90.02;,脂肪1.47;,蛋白质1.84;,乳糖6.26;,灰分0.42;.氨基酸种类齐全,数量充足,比例合理;9种人体必需氨基酸的含量占氨基酸总量的42.52;.矿物质和维生素含量丰富,钙磷比1.7∶1,硒含量是牛乳的5.16倍,维生素C含量是牛乳的4.75倍.驴乳属乳清蛋白性乳类,乳白蛋白和乳球蛋白的含量占蛋白质总量的60;以上;不饱和脂肪酸含量高,人体必需脂肪酸亚油酸和亚麻酸的含量占脂肪酸总量的30.7;,比牛乳高27.2个百分点;胆固醇含量为2.2 mg/100 g,是牛乳的14.7;.在各种家畜乳中,驴乳的成分和人乳最为接近,可作为婴幼儿代乳品或代乳品基料.驴乳的化学成分和营养特点决定其在乳制品和保健食品的开发中具有较大的潜力.深入研究、开发驴乳,对于扩大驴资源的综合利用,发展营养保健事业,增加贫困地区农牧民经济收入,具有积极意义.     

酸奶中嗜热乳酸链球菌的分离鉴定及益生特性研究

[目的]探讨酸奶中嗜热乳酸链球菌的益生特性。[方法]利用MRS琼脂培养基从酸奶中分离嗜热乳酸链球菌,通过糖发酵试验对其进行生化鉴定。研究嗜热乳酸链球菌的抑菌特性和胆盐耐受性,并分析不同pH值对嗜热乳酸链球菌的的影响。[结果]镜检结果表明该菌为革兰氏阳性,经生化鉴定可确定该菌为嗜热乳酸链球菌。嗜热乳酸链球菌对人体肠道内的常见病原菌有抑制作用,尤其是对大肠杆菌和金黄色葡萄球菌的抑制作用明显。嗜热乳酸链球菌可以耐受人体肠道的胆盐环境,并在其特定部位生存。嗜热乳酸链球菌可耐受强酸,能在胃酸中存活,在近中性pH值环境中生长较好。[结论]嗜热乳酸链球菌可在人体肠道内发挥益生作用,保护机体免受病原菌的侵害。     

Immunochemical characterization of polyribonucleotides

The degree of organization of polyribonucleotides determines their modalities of reaction with antibodies (NG-I) which are present in serums of animals hyperimmunized with ribosomes. The immunochemical behavior of the highly helical two-stranded complex of polyadenylic acid and polyuridylic acid and the corresponding three-stranded complex of one molecule of polyadenylic acid and two molecules of polyuridylic acid can be determined from examination of the associatinge and nonassociating mixtures of polyadenylic and polyuridylic acids. The immunochemical characteristics of various forms of polyinosinic acid in solution are described.     

DNA-membrane complex: macromolecular content and stimulation of enzymatic activity by polyadenylic acid

A DNA-cell membrane complex has been isolated from cell suspensions of virulent pneumococci by sarcosyl lysis followed by centrifugation on a sucrose gradient. When polyadenylic acid plus the eight naturally occurring deoxyribonucleosides and deoxyribonucleotides are added to cell suspensions, the percentage of total DNA in the complex increases with incubation time. This increase is not observed in unsupplemented cell suspensions. However, the percentages of RNA, protein, and phospholipid do not increase with incubation time in either supplemented or control complexes. A variety of deoxyribonucleotide kinases and the DNA polymerase are also detected in the DNA-membrane complex, and their specific activities are greater in complexes extracted from supplemented cell suspensions than in those extracted from controls.     

基于昼夜节律的牛奶品质研究

【背景】昼夜节律是生物界普遍经历的自然现象,随着昼夜节律的变化,生物细胞内部发生着不同的反应和变化,并对动物机体的代谢和生理机能也产生不同的影响,进而影响动物的生长、生产和繁殖等活动。牛奶是人类喜爱的接近完美的食物,由于受科技水平的限制,多年来,人们对牛奶的认识仅停留在营养层面,而忽略昼夜节律对牛奶理化特性和生理功能的影响。【目的】通过对昼夜牛奶的理化特性和生理功能研究,提出根据牛奶不同时段的生理功能收集牛奶,为昼夜牛奶的分类加工和科学饮用奠定了理论依据。【方法】分别采集夜间（5:00,产生时间21:00-5:00）和白天(13:00,产生时间6:00-13:00)的牛奶检测其营养组成,并通过脂质组学检测牛奶脂肪酸组成。提取上清液检测牛奶的理化指标,包括超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、谷胱甘肽还原酶（GR）、丙二醛（MDA）等氧化还原指标;褪黑素（melatonin,MT）、生长激素（GH）、三碘甲状腺原氨酸（T3）、胰岛素（INS）、胰高血糖素（GCN）等代谢相关激素和免疫球蛋白A(Ig A)、免疫球蛋白G(Ig G)、肿瘤坏死因子α(TNF-α)、白介...     

Milk for humans: Evolving perceptions of an all-time mother science

Milk is the most nourishing natural biofluid and almost an ideal functional food for humans of all ages. The objective of this review article is to delineate global nutritional and health implications of main live-stock dairy products for optimum postmodern life quality. Milk bioactives contribute considerably to meeting nutrient requirements while offering potentials to reduce risks of cancers, traumas and metabolic disorders. Milk functions beyond its nutritive worth. Cow milk intake by lactating mothers enriches breast milk ??-lactoglobulin and ovalbumin. Milk intake leads to more standard body frame structure and bone health. Milk immunoglobulins act against Enterotoxigenic Escherichia coli. Casomorphins, immunostimulating peptides, and ACE-inhibitory peptides modulate the gut nutrient assimilation. Whey proteins are insulinotropic and medium chain fatty acids improve insulin action. Peptides along with calcium may reduce blood pressure and cholesterol. Milk improves folate availability, and reduces homocysteinemia and heart infarcts. Ewe milk is richer than cow milk in riboflavin, thiamine, niacin, pantothenic acid, vitamin B₆, vitamin B₁₂ and biotin. Goat milk has less ??-s-1-casein, ??-carotene, agglutinin; and is lower in citric acid, Na, Fe, S, Zn, Mo, ribonuclease, alkaline phosphatase, lipase, xanthine oxidase, N-acetylneuraminic acid, orotic acid, pyridoxine, folate, vitamin B₁₂, and vitamin C than cow milk. Goat milk is richer in Ca, K, Mg, P, Cl, Mn, vitamins A and D, nicotinic acid, choline, inositol, medium-chain FA, small diameter fat globules than cow milk. Goat milk is a suitable substitute in allergies, and with low orotic acid might prevent fatty liver. Lysozyme-rich milk has been produced with transgenic dairy goats to prevent intestinal disorders in infants. Donkey and horse milks are considered optimal substitutes for human and cow milk in minimizing allergies and hyperlipidemia related complexities. Effective education and data dissemination are the ongoing obligations for unbiased milk science to be adequately perceived and applied by postmodern human populations.