Studies on the mechanism of light-dependent germination of akinetes of blue-green algae

This paper deals with the role of light in the germination of akinetes of Anabaena azollae. The two maxima action spectra are situated at 385 and 615 nm and the stimulation of the germination process by photosynthate was confirmed. The photoreceptor absorbing at 385 nm was identified as a flavin and that at 615 nm as a phytochrome. A model is suggested for the mode of action of light in the germination of akinetes of blue-green algae.C. Tsui     

The role of the carbohydrate moiety on the size heterogeneity and immunologic determinants of human testosterone-estradiol-binding globulin

Human testosterone-estradiol-binding globulin (hTeBG) has been purified to apparent homogeneity by several laboratories using procedures which, in most instances, were labor intensive. In this report, hTeBG was purified from pregnancy serum by a newly developed two step procedure involving sequential affinity chromatography and ion-exchange high performance liquid chromatography (ion-exchange HPLC). The purity of the final product was confirmed by silver stained SDS-polyacrylamide gel and reverse phase HPLC monitored at 206 nm. hTeBG purified by ion-exchange-HPLC maintained binding activity by Dextran coated charcoal (DCC) assay and size heterogeneity on SDS-polyacrylamide gels which were indistinguishable from those of the proteins purified by conventional chromatography. Removal of the carbohydrate moiety from the molecule by both enzymatic and chemical treatment reduced the apparent molecular size and eliminated lectin binding of hTeBG subunits. Deglycosylation did not, however, abolish or alter the distribution of the protomeric forms of this subunit. We conclude that hTeBG is a dimer whose monomer exhibits two protomeric forms which is not a result of carbohydrate heterogeneity. In addition, disialylated and deglycosylated hTeBG exhibited antigenic determinants identical to the native protein.     

亮叶杨桐(石芽茶)中黄酮类成分的研究

从广西产亮叶杨桐(Adinandra nitida Merr.ex H.L.Li)中,分得三种黄酮类成分:Ⅰ、Ⅱ和Ⅲ。经IR、UV(位移诊断)、熔点、混熔点、薄层层析鉴定:Ⅰ为芹菜素(Apigenin);Ⅱ为芹菜素-5-0-α-L-吡喃鼠李糖基(1→4-6~(?)-乙酰基-β-D-吡喃葡萄糖吡;Ⅲ为芹菜素-5-0-α-L-吡喃鼠李糖基(1→4)-β-D-吡喃葡萄糖甙。     

马立克氏病毒单克隆抗体的研究

获得了4株分泌马立克氏病毒(MDV)特异性单克隆抗体(McAb)的杂交瘤细胞:4BS10对MDV所有毒株呈阳性反应;4CN8 对MDV血清1,3型毒株发生反应;2BN90和4CN24只对MDV血清1型毒株有阳性反应。3个McAb属IgG1,1个为IgG2b,均不中和MDV,免疫扩散试验也无沉淀线。对禽白血病毒(ALV)无交叉反应。 以2BN90和辣根过氧化物酶、异硫氰酸荧光素的结合物进行直接酶联免疫吸附试验和直接荧光抗体试验,均获得成功。抗体滴度前者为1/51,200,后者为1/640。对ALV无交叉反应。     

冷冻液温和季节对鼠尾过冷点的影响

为研究动物对寒冷的适应性,将鼠尾置于冷液浸冻,发现在一定条件下鼠尾组织可发生过冷现象。实验表明,鼠尾组织的过冷点和冷冻液温有关,同一季节冷冻液温越低过冷点越高;而不同季节相同冷冻条件下,冬季鼠尾组织的过冷点明显低于春季。 动物肢体组织的过冷特性是动物的抗寒冷特性,它和组织自身的物理化学性质有关。理沦证明,过冷度(△T)和表面张力(O)、摩尔质量(M),冰点(Ti)、密度(p)、摩尔凝固热(△H)及冰胚临界半径(rk)有关,其关系式为△T=26MTi/p△Hrk.     

肝素修饰尿激酶某些性质的研究

本文对比研究了溴化氰活化及高碘酸活化肝素修饰的两种修饰尿激酶的性质。结果表明尿激酶在溴化氰活化肝素(肝素CN),高碘酸钠活化肝素(肝素I_4)的共价修饰后,其残余自由氨基分别是64％和52％;酶活性分别保留94％和90％;抗胃蛋白酶水解以及抗冻融变性的能力均高于天然酶;在离体血浆中的失活速变低于天然酶。本文还对修饰酶进行了萤光及紫外差光谱的分析,讨论了修饰过程对构象的影响。     

The rabbit C family of short, interspersed repeats. Nucleotide sequence determination and transcriptional analysis

When the entire adeno-associated virus (AAV) genome is inserted into a bacterial plasmid, infectious AAV genomes can be rescued and replicated when the recombinant AAV-plasmid DNA is transfected into human 293 cells together with helper adenovirus particles. We have taken advantage of this experimental system to analyze the effects of several classes of mutations on replication of AAV DNA. We obtained AAV mutants by molecular cloning in bacterial plasmids of naturally occurring AAV variant or defective-interfering genomes. Each of these mutants contains a single internal deletion of AAV coding sequences. Also, some of these mutant-AAV plasmids have additional deletions of one or both AAV terminal palindromes introduced during constructions in vitro. We show here that AAV mutants containing internal deletions were defective for replicative form DNA replication (rep-) but could be complemented by intact wild-type AAV. This indicates that an AAV replication function, Rep, is required for normal AAV replication. Mutants in which both terminal palindromes were deleted (ori-) were also replication defective but were not complementable by wild-type AAV. The cis-dominance of the ori- mutation shows that the replication origin is comprised in part of the terminal palindrome. Deletion of only one terminal palindrome was phenotypically wild-type and allowed rescue and replication of AAV genomes in which the deleted region was regenerated apparently by an intramolecular correction mechanism. One model for this correction mechanism is proposed. An AAV ori- mutant also complemented replication of AAV rep- mutants as efficiently as did wild-type AAV. These studies also revealed an unexpected additional property of the deletion mutants in that monomeric single-stranded single-stranded DNA accumulated very inefficiently even though monomeric single-stranded DNA from the complementing wild-type AAV did accumulate.     

Lymphocyte ecto-5'-nucleotidase activity in infancy: increasing activity in peripheral blood B cells precedes their ability to synthesize IgG in vitro

Ecto-5'-nucleotidase activity was measured in peripheral blood lymphocytes isolated from serial specimens from nine healthy full-term infants and two premature infants at 0, 2, 4, and 6 mo of age. The postnatal nadir in activity was 7.1 +/- 2.0 nmol/hr/10(6) cells, which is the same as the activity in cord blood lymphocytes (7.0 +/- 2 nmol/hr/10(6) cells). The activity rose twofold to 13.2 +/- 3.8 nmol/hr/10(6) cells at 6 mo of age (p less than 0.001, paired t-test), which is similar to the activity in adult peripheral blood lymphocytes (14.1 +/- 6.3 nmol/hr/10(6) cells). This increased activity in total lymphocytes reflects increased activity in the B cell population. B cell ecto-5'-nucleotidase activity in two infants at 12 to 13 mo of age was 19.3 and 25.2 nmol/hr/10(6) cells, values that are four-to fivefold higher than for cord blood B cells (5.6 +/- 2.8 nmol/hr/10(6) cells) and within the normal range for adult B cells (27.9 +/- 12 nmol/hr/10(6) cells). In spite of a greatly expanded peripheral blood B cell population, studies of immunoglobulin biosynthesis in vitro demonstrated that infant peripheral blood B cells are functionally immature with no synthesis of IgG in response to Epstein Barr virus. Thus, the increase in peripheral blood B lymphocyte ecto-5'-nucleotidase activity in infants precedes their acquisition of a capacity for IgG synthesis in vitro. Data from a hypogammaglobulinemic infant revealed a persistently low ecto-5'-nucleotidase activity over a 10-mo period until at 14 mo of age the activity was 8.8 nmol/hr/10(6) cells in total lymphocytes and 13.0 nmol/hr/10(6) cells in B cells, which correlated with in vivo and in vitro evidence of delayed B cell maturation. Thus, ecto-5'-nucleotidase activity may be a useful cell surface marker in studies of human postnatal B cell maturation.     

Phenotype and function of engrafted maternal T cells in patients with severe combined immunodeficiency

Engrafted maternal T cells from two patients with severe combined immunodeficiency (SCID) and graft-vs-host disease (GVHD) were characterized for surface phenotype, function, and ecto-5'-nucleotidase (ecto-5'-NT) activity. The majority of engrafted T cells from both patients were T6-, T3+, and Ia+; the ratio of T4+:T8+ cells varied from 0.89 to 3.1 for Patient 1 and was 0.17 for Patient 2. The sum of T4+ + T8+ cells was greater than the number of T3+ cells, and approximately one-third of the patients' T cells were T3-. Two-color immunofluorescent staining showed that one-third of the T cells from Patient 1 had a novel cell surface phenotype (T6-, T3-, T4+, T8+) that was not previously described. T cells from Patient 1 failed to proliferate in response to allogeneic cells or specific antigen and provided little help for PWM-driven Ig synthesis in vitro. However, they did suppress Ig synthesis in vitro and proliferate in response to PHA and Con A; thus they appeared to be more mature than the T cells of Patient 2 and of most previously reported patients with SCID and maternal T cell grafts. Both patients lacked detectable lymphocyte ecto-5'-NT activity, suggesting that either the ecto-5'-NT activity of maternal T cells is lost after engraftment or that a specific subset(s) of ecto-5'-NT-negative maternal T cells predominates in infants with SCID and GVHD. Thus, in vitro T cell function and the proportions of T cells bearing T4 and T8 may vary in SCID patients with maternal T cell grafts. However, the presence of the Ia antigen and the absence of ecto-5'-NT activity may be consistent features of activated maternal T cells responsible for GVHD.     

Comparison of rabbit androgen binding protein with testosterone estradiol binding globulin--I. Physical and chemical properties

Rabbit epididymal androgen binding protein (rbABP) and serum testosterone estradiol binding globulin (rbTeBG) were purified and their physicochemical properties compared. Both proteins bound dihydrotestosterone (DHT) with high affinity. Both contained two components, Heavy (H) and Light (L), and their molecular weights and pI values were comparable. rbABP and rbTeBG were different with regard to their ConA-Sepharose binding property. rbABP was not bound by ConA-Sepharose while rbTeBG was found and retained by this lectin; thus, rbABP and rbTeBG differed in their carbohydrate structure. Peptide mapping on SDS-PAGE indicated that the H components of rbABP and rbTeBG were distinct even though they showed a high degree of homology. By contrast, the L components of these two proteins appeared to be identical. The structure of the steroid binding sites of these two proteins was analyzed by peptide mapping of [1,2(3)H]17 beta hydroxy-androsta-4,6-dien-3-one photoaffinity labeled protein. The size distribution of radioactive peptide fragments generated appeared to be identical for these two proteins. However, the distribution of labeled peptides was slightly different when examined by high pressure liquid chromatography (HPLC). The observations suggest that the differences between rbABP and rbTeBG might reside not only in carbohydrate moieties but also in their amino acid sequences.