A map of photolytic and tryptic cleavage sites on the beta heavy chain of dynein ATPase from sea urchin sperm flagella

NH2-terminal analysis of the alpha and beta heavy chain polypeptides (Mr greater than 400,000) from the outer arm dynein of sea urchin sperm flagella, compared with that of the 230,000- and 200,000-Mr peptides formed upon photocleavage of dynein by irradiation at 365 nm in the presence of vanadate and ATP, shows that the NH2 termini of the intact chains are acetylated and that the 230,000- and 200,000 Mr peptides constitute the amino- and carboxy-terminal portions of the heavy chains, respectively. Tryptic digestion of the beta heavy chain is known to separate it into two particles, termed fragments A and B, that sediment at 12S and 6S (Ow, R. A., W.-J. Y. Tang, G. Mocz, and I. R. Gibbons, 1987. J. Biol. Chem. 262:3409-3414). Immunoblots against monoclonal antibodies specific for epitopes on the beta heavy chain, used in conjunction with photoaffinity labeling, show that the ATPase-containing fragment A is derived from the amino-terminal region of the beta chain, with the two photolytic sites thought to be associated with the purine-binding and the gamma-phosphate-binding areas of the ATP-binding site spanning an approximately 100,000 Mr region near the middle of the intact beta chain. Fragment B is derived from the complementary carboxy-terminal region of the beta chain.     

Epitopes of an influenza viral peptide recognized by antibody at single amino acid resolution

Antibodies raised against the synthetic peptide corresponding to the carboxy-terminal 24 amino acids (305-328) of the heavy chain of the hemagglutinin molecule of influenza virus A/X-31 (H3) bind this peptide at three antigenic sites. These sites were identified by assaying binding of polyclonal BALB/c mouse antipeptide sera to the complete set of all possible di-, tri, tetra-, penta-, hexa-, hepta-, and octapeptides homologous with the 24-residue sequence. Individual epitopes were defined and essential residues identified by testing the binding of monoclonal antibodies to sets of peptide analogues in which every one of the homologous residues was replaced in turn by each of the 19 alternative genetically coded amino acids. The immunodominant epitope was shown to be a linear sequence of five amino acids, 314LKLAT318. Replacement of any one of these residues with any other amino acid resulted in loss of antibody binding, indicating that all five are essential to the interaction and that they are probably contact residues. Another antigenic site contains at least two overlapping epitopes: polyclonal sera recognize predominantly an epitope or epitopes encompassed by the linear sequence 320MRNVPEKQT328, whereas the epitope defined by a particular monoclonal antibody comprises the seven amino acids 322NVPEKQT328, of which N322, E325, and Q327 were implicated as contact residues.     

人胸腺上皮细胞培养及其分泌产物

本文通过降低培养基中血清含量,向RPMI 1640培养基中补加三碘甲腺原氨酸而获得一种人胸腺网状上皮细胞占优势生长的培养物。在此培养基中细胞经传代培养长达90天,仍维持正常形态特征。胸腺组织在培养14天后,新生细胞的突起形成网状结构,细胞化学检查和电镜观察表明具有丰富的分泌颗粒,囊泡及张力原纤维束和桥粒等上皮细胞特征。收集合并细胞培养液,经部分纯化后检查其生物活性,表现出具有促进玫瑰花结形成和降低胸腺细胞TdT活性的作用,说明培养细胞的分泌产物具有胸腺激素活性。根据形态学,细胞化学和生物活性检测结果,我们倾向于认为该培养物主要为网状上皮细胞。     

小麦叶绿体中CTK结合蛋白的结合活性研究

叶绿体中存在着与细胞分裂素(CTK)专一结合的蛋白质。这一蛋白与6-苄氨基嘌呤(6 BA)的亲和力很强,解离常数达3.7×10~(-8)mol/L。最大结合量为10.7 pmol 6 BA/mg蛋白,Seatchard分析表明只有一类结合位点。不同的叶绿体纯化步骤对CTK结合蛋白的活性有不同的影响,分离步骤少而快速的差速离心法可以得到具有较高结合活性的叶绿体。叶绿体经分离纯化后,低温保存时的结合活性较稳定,-20℃以下可以较长期保存。用EDTA预处理叶绿体,不降低CTK结合蛋白对6 BA的结合活性,而用高浓度的NaCl处理,可以使叶绿体结合6BA的能力明显下降。这说明EDTA不能使CTK结合蛋白从叶绿体膜系统表面解离,而高浓度NaCl则有这种可能性。     

水稻原生质体产生细胞团的冰冻保存和冻后再生植株形成

水稻(Oryza sativa L.)原生质体产生的细胞团加上10-20％的二甲亚枫(DMSO)和10-20％的蔗糖,置于液氮中保存。冻后细胞生存率达到对照的40-50％。存活的细胞在附加2×10~(-5)mol/l 2,4-D 的Linsmier-Skoog(Ls)固体培养基上再生长,然后将形成的愈伤组织块转到附加10~(-6)mol/l NAA,4×10~(-6)mol/l 激动素和10~(-6)mol/l 2 IP 及8％的蔗糖的 LS培养基上分化出芽并形成植株。     

Receptor-like cytokinin-binding protein(s) from barley leaves

Purified fractions of soluble proteins from barley leaves have been shown to contain specific binding sites fortrans-zeatin, a natural cytokinin. Such binding is very strong in vitro in concentrated solutions of some salts (ammonium sulfate or potassium phosphate) with optimum at pH 7–8 and temperature within the range 0–20°C. The cytokinin-binding sites have high affinity for zeatin (K_d1.5·10^–8 M) and low capacity corresponding to 1–1.5 pmol zeatin per milligram of initial soluble protein. Cytokinin binding is reversible; it is due to protein (or proteins) with molecular weight 40–45 kDa. This protein(s) does not bind³H-adenine and³H-abscisic acid. The ability of various compounds to displace³H-zeatin from its high-affinity binding sites is in strict accordance with their biological cytokinin activities. Other phytohormones as well as fusicoccin do not displace³H-zeatin from its binding sites. Specific zeatin binding is sensitive to heat, alkali, and pronase, but not to RNase treatment. The 150- to 200-fold purification of cytokinin-binding proteins was achieved by a combination of ammonium sulfate precipitation and Ultrogel AcA-54- and DEAE-cellulose chromatography. The zeatin-binding protein(s) from barley leaves is suggested to take part in cytokinin action in vivo.     

An electronic mechanism in the action of drugs, ATP, transmitters and other cardinal adsorbents. II. Effect of ouabain on the relative affinities for Li+, Na+, K+, and Rb+ of surface anionic sites that mediate the entry of Cs+ into frog ovarian eggs

Ouabain enhanced the inhibitory effects of Li+, Na+, and K+ on the rate of Cs+ permeation into frog ovarian eggs while it reduced the inhibiting effect of Rb+. The data agree with earlier demonstrated effects of ouabain on the rank order of selective accumulation of the five alkali-metals in frog muscles and on the relative effectiveness of glycine, Li+, Na+, K+, Rb+, and Cs+ in inhibiting the rate of entry of Cs+ into frog sartorius muscle. In all three cases, the ouabain behaved as an electron-donating cardinal adsorbent (EDC) causing a rise of the electron density (c-value) of the beta- and gamma-carboxyl groups in the cell cytoplasm (for selective accumulation) and on the cell surface (for selective ion permeation). Explanations based on the association-induction hypothesis were offered why an EDC like ouabain does not initiate cell activation (like veratridine does) and why Ca++ and tetradotoxin delays or inhibits physiological and artificial cell activation.     

Vimentin expression in oocytes, eggs and early embryos of Xenopus laevis

Immunocytochemical studies using a monoclonal anti-porcine vimentin antibody reveal a well-organized pattern of staining in Xenopus laevis oocytes, eggs and early embryos. The positions of Xenopus vimentin and desmin in two-dimensional (2D) polyacrylamide gels were first established by immunoblotting of muscle Triton extracts with anti-intermediate filament antibodies (anti-IFA), which cross-react with all intermediate filament proteins (IFPs). The anti-porcine vimentin reacts with vimentin and desmin in muscle 2D immunoblots, but only reacts with one polypeptide in oocyte blots in the position predicted for vimentin (Mr 55 x 10(3), pI 5.6). Using an anti-sense probe derived from a Xenopus vimentin genomic clone in RNase protection assays, we show that expression of vimentin begins in previtellogenic oocytes. The level of expression remains constant throughout oogenesis and in unfertilized eggs. These data suggest that vimentin is expressed in oocytes and eggs. Most interestingly, the immunocytochemical results also show that vimentin is present in the germ plasma of oocytes, eggs and early embryos. It is therefore possible that vimentin has an important role in the formation or behaviour of early germ line cells.     

新生儿巨细胞病毒感染的检测

建立了用ELISA检测巨细胞病毒(HCMV)IgA抗体的方法,並用于检测北京地区100对母婴的HCMV抗体,母血、脐带血、母乳中HCMV-IgG抗体的阳性率分别为83％,75％和38％,HCMV-IgA抗体的阳性率分别为19％,15％和58％,对其中的16名婴儿半年后追踪观察,5名出生时母、脐血全为阴性的,有2名抗体阳转。8名出生时母、脐血均阳性的,有1名IgA仍阳性並检查发现肝大肋下二指。另1名IgG持续阳性,其他6名婴儿抗体转阴。3名出生时母血HCMV-IgG阳性者中,1名婴儿IgA和‘gG转阳,此时母亲IgA也阳转。随访的16名婴儿中有3名可能是生后半年内受HCMV感染。     

银额果蝇的B染色体研究 2.昆明群体的生活力和B染色体的关系

本文分析了钮额果蝇的生活力和B染色体的关系。结果表明,银额果蝇的B染色体在其生长和发育过程中具双重性调节作用。一方面,B染色体以单一的形式存在于单雌系核型中,即1B或2Bs,可刺激生长、发育,增强生活力。另一方面,在单雌系的细胞中存在多条B染色体,并形成核型多态性,这似乎对生长和发育又有一定的抑制作用而减弱其生活力。