砂鼠利什曼原虫(Leishmania gerbilli)的亚显微结构

砂鼠利什曼原虫(Leishmania gerbilli)存在于我国西北甘肃某地的砂土鼠或大砂鼠(Rhombomys opimus)体内,是中国特有的种类,王捷等60年代分离培养成功。对L.gerbilli的前鞭毛体的亚显微结构的观察表明:1.质膜下微管间距约为50nm,比别的利什曼原虫的宽;2.鞭毛基部极少观察到基板(basal plate);3.线粒体发达,从动基体所在部位伸向虫体各个部位,内有复杂的结构;4.在通常情况下,L.gerbilli的动基体呈棒状,但当细胞膨胀后则无论在光镜或电镜下动基体均呈扁环结构;5.虫体后部有发达的复片层结构。这一结构由一系列的膜卷绕成,其意义不明。     

Characterization of an HSP70 Cognate Gene Family in Arabidopsis

Analysis of the polypeptide composition of extracts from heat-shocked leaves of Arabidopsis indicated the presence of at least 12 HSP70-related polypeptides, most of which were constitutively expressed. In vitro translation of mRNA from heat-shocked and control leaves indicated that the amount of mRNA encoding four HSP70 polypeptides was increased strongly by heat-shock. Three Arabidopsis genes which exhibit homology to a Drosophila HSP70 gene were cloned. Two of the three genes are arranged in direct orientation approximately 1.5 kilobases apart. The third gene is not closely linked to the other two. Nucleotide sequence analysis of the 5′ regions of the two linked genes revealed that both contain a TATA box, the CAAT motif, and several short sequences which are homologous to the Drosophila heat-shock consensus sequence. The deduced partial amino acid sequence of the open reading frames were 79 and 72% homologous to the corresponding regions of the Drosophila HSP70-cognate and HSP70 sequences, respectively. As with the two maize HSP70 genes which have been characterized, and the Drosophila HSP70-cognate genes, the Arabidopsis genes contained a putative intron in the codon specifying amino acid 72. Analysis of mRNA levels with gene-specific oligonucleotide probes indicated that two of the genes were not expressed or were expressed at very low levels in leaves during normal growth or after heat-shock, whereas the other gene was constitutively expressed. By analogy with the results of similar studies of other organisms, it appears that the three cloned genes are members of a small family which are most closely related to the HSP70-cognate genes found in other species.     

Translational alterations in maize leaves responding to pathogen infection, paraquat treatment, or heat shock : polysome dissociation and accumulation of a 57 kilodalton protein

Translational alterations occur in maize (Zea mays L.) leaves stressed by pathogen infection or herbicide paraquat treatment. These translational changes include: (a) dissociation of large polysomes to small polysomes, monosomes, and subunits; (b) a decreased rate of total protein synthesis; and (c) a reduced synthesis of several proteins by polysomes in vitro. The polysome dissociation was neither due to an extraction artifact nor to degradation of RNA by RNase. The protein patterns of polysomes isolated from leaves inoculated with Bipolaris maydis at 6 to 48 hours showed an increase in the intensity of a 57 kilodalton protein. When inoculated with less virulent pathogens, such as B. zeicola, Exserohilum turcicum, or Colletotrichum graminicola, the protein was accumulated in polysomes of leaves at 24 to 48 hours after inoculation. The 57 kilodalton protein was also accumulated in polysomes of maize leaves responding to heat shock or herbicide paraquat treatments. The purified 57 kilodalton protein reassociated with polysomes isolated from healthy leaves and inhibited polysomal translation in vitro. Since the 57 kilodalton protein is rapidly accumulated in maize polysomes in response to various biological and environmental stresses and may affect protein synthesis, it may be involved in translational regulation of maize leaves during stress response.     

Signal transduction of gamma/delta T cell antigen receptor with a novel mitogenic anti-delta antibody

Human T lymphocytes express either alpha/beta- or gamma/delta-TCR in association with the CD3 complex. We have isolated a mAb, delta TCS1, that immunoprecipitated the gamma/delta-TCR heterodimer from cell lysates of Peer and Molt-13 leukemia cell lines. After dissociation of the gamma- and delta-chains of TCR by treatment with SDS, delta TCS1 specifically immunoprecipitated the delta-chain. This antibody bound to the surface of other gamma/delta-positive T cell lines and clones and was able to stimulate the proliferation of a minor cell population (0.9 to 4.0%) of resting human PBL. Upon binding to gamma/delta-TCR-bearing Molt-13 cells and PBL, delta TCS1 elicited a fura-2 Caa+ signal indicating that the gamma/delta-receptor is functionally similar to the alpha/beta-heterodimer. These data indicate that the delta TCS1 antibody recognizes an epitope on TCR delta-chain and its mitogenic activity should be useful in characterizing the functional properties of human gamma/delta-positive T lymphocytes.     

Rat lens gamma-crystallins. Characterization of the six gene products and their spatial and temporal distribution resulting from differential synthesis

We have isolated, purified and characterized six individual gamma-crystallin polypeptides present in the rat lens. Comparison of their amino acid compositions with the known structure of the six gamma-crystallin genes permits a one-to-one correspondence to be made between each protein synthesized and the encoding gene. This demonstrates that each of the six genes is actually expressed in vivo. Two classes of three gamma-crystallins each, which we have designated classes gamma ABC and gamma DEF, are known to exist, on the basis of internal sequence homology. We have measured the temperature-dependent phase-separation characteristics of solutions of the six purified gamma-crystallins, and find that the three members of the gamma DEF class (gamma 2-2, gamma 3-1 and gamma 4-1) are all cryo-proteins with relatively high phase-separation temperatures, whereas the three gamma ABC crystallins (gamma 1-1, gamma 1-2 and gamma 2-1) do not show phase separation above -7 degrees C. We have measured the spatial distribution in rat lens of each of the alpha-, beta- and gamma-crystallins as a function of age from 1 to 420 days, using size-exclusion and ion-exchange high-pressure liquid chromatography (HPLC). Our findings in the cortical layer permit us to establish the differential synthesis of each of the crystallins during lens development. Particular attention has been devoted to the spatial and temporal distribution of the six individual gamma-crystallins. Up to birth, synthesis of the three components of the gamma DEF class predominates, and in particular that of gamma 2-2. In subsequent development the three components of the gamma ABC class assume a greater proportion of monomeric crystallins synthesized, while beta s-crystallin synthesis predominates in late development. Our analysis of different layers within single lenses provides novel information on spatial gradients of the water-soluble and water-insoluble protein fractions as a function of age. We consider the consequences of these findings for lens transparency and opacity in both rat and mouse lens. We show that the high concentrations of gamma DEF-crystallins appear to be responsible for the opacity known to occur in young rat lenses. We conclude from these observations that close control of the differential synthesis of gamma-crystallins plays an important role in maintaining lens transparency during development.     

九连小蘖悬浮培养细胞生理生化研究 Ⅰ.细胞生长与培养液的电导率和过氧化物酶活性的变化

本文报道了九连小蘖细胞悬浮培养过程中,细胞生长与培养液的电导率、pH值、可溶性糖含量及过氨化物酶活性的变化。实验表明细胞生长曲线与培养液的电导率、可溶性糖含量变化的曲线恰成镜像关系。而细胞生长曲线与培养液的过氨化物酶活性变化的曲线相互平行。从而,可以通过监测培养液的电导率和过氧化物酶活性的变化来了解细胞生长状况,并可作为植物细胞培养过程中生物量增长的参考指标。