Growth Curve and Distribution of Rous Sarcoma Virus (Bryan) in Japanese Quail

On primary infection with the Bryan strain of Rous sarcoma virus (RSV), the growth curve of the virus in the brain of Japanese quail was similar to that observed in chicks and turkey poults. Infectious virus disappeared from the brain after inoculation. After an eclipse period during which no virus was detectable, infectious virus began to appear at 2 days and reached maximal titers in the brain samples at 7 days after inoculation. When Japanese quail were infected intracerebrally with RSV, relatively high titers of virus were recovered from brain tissue but not from liver, lung, kidney, or blood of moribund birds. Only tumors produced in the wing web of quail infected subcutaneously yielded high titers of virus. Other tissues yielded no virus, even though wing web tumors appeared as early as in chicks similarly infected. RSV could be propagated in the wing web of quail for at least 14 passages without any loss of infectivity. On the other hand, serial passage in quail brain resulted in a progressive loss of infectivity until virus was completely lost.     

Factors Controlling the Production of Lysogenic Cultures of B. megatherium

(1) The proportion of infected B. megatherium cells which develop lysogenic colonies depends on the number and kind of infecting virus particles and on the culture medium in which the cells are growing. (2) Cells infected with 100 or more T virus particles (from megatherium 899) in yeast extract peptone disintegrate, produce very few virus particles, and less than one lysogenic colony per 10⁷ infected cells. Cells infected with one or a few particles produce 500 to 1000 virus particles each and about 30 lysogenic colonies per 10⁷ infected colonies. (3) T phage obtained from lysogenic magatherium KM cultures produces many more lysogenic cells than does the original megatherium 899 virus. (4) Cells infected with megatherium 899 T virus in peptone medium and then transferred to asparagine medium give rise to 10⁶ lysogenic colonies per 10⁷ infected cells and this transformation will occur even after the infected cells have been in peptone for 60 to 90 minutes and are beginning to produce virus particles. (5) Continued growth of KM strain with either C or T virus from megatherium 899 for several hundred generations in the steady state apparatus results in a lysogenic strain which produces several different types of virus.     

粪产碱菌（Alcaligenes faecalis）吸收氢和同化CO2的特性

应用同位素氚(T_2)和~13C(~13CO_2),证明了水稻联合固氮菌——粪产碱菌A—15是一种含有吸氢酶的兼性化能自养细菌,具有较强的吸氢能力,吸氨酶活性可达到13.11μmol H_2 ml~(-1) cultureh~(-1);同时,它还可利用H_2为能源同化CO_2营化能自养生活,其RuBPC活性为24.65 nmolCO_2 mg~(-1) protein min~(-1)。无论在自养还是异养条件下,H_2都支持、并促进固氮活性。粪产碱菌培养在N_2条件下比在NH_4~ 条件下能积累更多的多聚-β羟基丁酸(PHB)。     

正常月经周期妇女卵泡液中激素水平的变化

本文测定了24例正常月经妇女在不同时相、不同大小卵泡的卵泡液中雌二醇(E_2)、孕酮(P_0)、雄烯二酮(A)、睾酮(T)、卵泡刺激素(FSH)、黄体生成素(LH)和催乳素(PRL)的含量,并分析其与外周血中相应激素浓度的关系。测定结果显示:小卵泡的卵泡液中E_2、Po,FSH,LH水平低于大卵泡中水平,而A和T水平则相反。排卵前大卵泡中E_2(9815nmol/L),P_0(3316nmol/L),FSH(1.34IU/L)和LH(3.9lIU/L)达最高值。A(280nmol/L)和T(137nmol/L)却较小卵泡中水平低(相应为692nmol/L和176nmol/L)。PRL水平在大小卵泡中无显著性差异。卵泡液中甾体激素水平高于外周血7—20.000倍,FSH、LH水平为外周血的10—80％,PRL水平为60％—3倍。     

水分胁迫对小麦叶片光合作用的影响及其与抗旱性的关系

在水分胁迫初期,两个小麦品种叶片光合速率,气孔导度和细胞间隙CO_2浓度降低,气孔限制值增加,光合速率的降低主要是气孔因素的限制。中度到严重水分胁迫使叶片光合速率、气孔导度和气孔限制值降低,细胞间隙CO_2浓度明显增加,且叶圆片放氧能力,叶绿体Hill反应、叶绿素荧光强度和表观量子产额降低,此时光合速率的降低主要是叶肉细胞光合活性的下降引起的。抗旱性弱的郑引一号叶肉细胞光合活性比抗旱性强的丰抗13更容易受到水分胁迫的影响。     

Gene technology-based antimetabolite design: the use of an in vitro protein expression system to facilitate antimetabolite design for virally-induced human diseases and malignant conditions

A precondition for the chemotherapeutic treatment of a variety of virally-induced human diseases and malignant conditions is a highly selective interaction of the drug molecule to be used with it's biological target. To ensure the development of novel, effective drugs, it is essential that the biological target is well characterised with regard to it's structure and activity. Such characterisation relies upon adequate amounts of pure target being available. One of the most important enzymatic importers for antimetabolites is the enzyme thymidine kinase. In this article an in vitro protein expression system is described which facilitates the production of milligram amounts of pure and biologically active thymidine kinase, from a number of important biological sources. Results have shown that the in vitro produced enzyme has the exact biochemical propeties of the in vivo enzyme. Thus the in vitro protein expression system is an ideal vechicle to facilitate an in depth investigation of the enzyme's biological properties.