云南10个民族红细胞酸性磷酸酶型分布调查

用淀粉凝胶电泳法对云南省汉族及9个少数民族的红细胞酸性磷酸酶(ACP_1)的表型分布进行了调查,检出A、BA和B3种表型,计算得云南汉、彝、白、傣、瑶、佤、哈尼、布朗、基诺和拉祜族ACP_1~A、ACP_1~B的基因频率依次为0.2067、0.7933;0.2406、0.7594;0.2341、0.7659;0.3750、0.6250;0.2300、0.7700;0.2727、0.7273;0.3594、0.6406;0.3036、0.6964;0.2381、0.76119和0.4474、0.5526。未发现ACP_1~C基因及其它稀有基因。研究表明,ACP_1表型的分布存在着一定的种族与民族差异。     

受白粉菌诱导大麦抗感等基因系蛋白质变化的双向电泳分析

分别对接种与否的大麦抗—感白粉病等基因系—叶期幼苗取材进行蛋白质双向电泳分析。结果表明,病原的侵入使抗—感两系在30Kd以下的低分子量区域的蛋白质发生了明显变化。接种48小时之后,抗病系在pH5.5、6.0、6.8及8.8附近出现了对照中所没有的蛋白质,而在pH6.0和8.8附近的蛋白质则较对照有减小的趋势;感病系在pH6.0附近蛋白质明显增多,在pH8.8处不仅在量上有大幅度提高,而且种类也有增加。结果还表明,抗—感系间在未接种的情况下双向电泳图谱也有差异,接种之后由于感病系在pH8.8处蛋白质的特异性合成,使抗—感两系间的差异缩小。     

经济发达地区稳定发展农业的对策

江苏省常熟市地处长江南岸阳澄湖畔,临近大中城市,距上海100km,离苏州、无锡、南通不足50km,历史上为苏南重点商品粮基地之一。因地理位置、地形、地貌及大气环流等因素所决定,常熟属北亚热带南部湿润地区,年平均气温15.5℃,年日照时数2202.9小时,年雨量1038.4mm。全市境内湖泊、河流纵横交错连结成网,有水域1.75×10~4ha,大小河流4477条。全境总面积1142.2km~2,北部较高,海拔3.11m左右,向南缓缓降低,最低地区海拔0.61m。     

Primary structure of rabbit skeletal muscle glycogen synthase deduced from cDNA clones

The complete amino acid sequence of rabbit skeletal muscle glycogen synthase was deduced from cDNA clones with a composite length of 3317 bp. An mRNA of 3.6 kb was identified by Northern blot analysis of rabbit skeletal muscle RNA. The mRNA coded for a protein of 734 residues with a molecular weight of 83,480. The deduced NH2-terminal and COOH-terminal sequences corresponded to those reported for the purified protein, indicating the absence of any proteolytic processing. At the nucleotide level, the 5' untranslated and coding regions were 79 and 90% identical for rabbit and human muscle glycogen synthases, whereas the 3' untranslated regions were significantly less similar. The enzymes had 97% amino acid sequence identity. Interestingly, the NH2 and COOH termini of rabbit and human muscle glycogen synthase, the regions of phosphorylation, showed the greatest sequence variation (15 of 19 mismatches and two insertion/deletion events), which may indicate different evolutionary constraints in the regulatory and catalytic regions of the molecule.     

Purified N-cadherin is a potent substrate for the rapid induction of neurite outgrowth

N-cadherin is the predominant mediator of calcium-dependent adhesion in the nervous system (Takeichi, M. 1988. Development (Camb.). 102: 639-655). Investigations using antibodies to block N-cadherin function (Bixby, J.L., R.L. Pratt, J. Lilien, and L.F. Reichardt. 1987. Proc. Natl. Acad. Sci. USA. 84:2555-2569; Bixby, J.L., J. Lilien, and L.F. Reichardt. 1988. J. Cell Biol. 107:353-362; Tomaselli, K.J., K.N. Neugebauer, J.L. Bixby, J. Lilien, and L.F. Reichardt. 1988. Neuron. 1:33-43) or transfection of the N-cadherin gene into heterologous cell lines (Matsunaga, M., K. Hatta, A. Nagafuchi, and M. Takeichi. 1988. Nature (Lond.). 334:62-64) have provided evidence that N-cadherin, alone or in combination with other molecules, can participate in the induction of neurite extension. We have developed an affinity purification procedure for the isolation of whole N-cadherin from chick brain and have used the isolated protein as a substrate for neurite outgrowth. N-cadherin promotes the rapid extension of neurites from chick ciliary ganglion neurons, which extend few or no neurites on adhesive but noninducing substrates such as polylysine, tissue culture plastic, and collagens. N-cadherin is extremely potent, more so than the L1 adhesion molecule, and comparable to the extracellular matrix protein laminin. Compared to laminin, however. N-cadherin promotes outgrowth from ciliary ganglion neurons extremely rapidly and with a distinct morphology. These results provide a direct demonstration that N-cadherin is sufficient to induce neurite outgrowth when substrate bound and suggest that the mechanism(s) involved may differ from that induced by laminin.     

The Streptomyces coelicolor A3(2) bldB region contains at least two genes involved in morphological development

Streptomyces coelicolor A3(2) bldB mutants are blocked in the formation of aerial hyphae. A phage library of wild-type S. coelicolor DNA was used to isolate recombinant phages which restore wild-type morphological development to several bldB mutants. Of several mutations, one, bld-28, previously mapped at bldB was not complemented by the cloned region, indicating that the bldB locus is composed of at least two distinct genes. Partial localization of bldB-complementing activity showed that a 1.5 kb fragment is sufficient for complementation of the bld-15 mutation whereas bld-17 requires the same region as well as additional sequences. Under stringent conditions, genomic DNA hybridizing to the cloned sequences was absent from other Streptomyces species, including the closely related Streptomyces lividans 66. DNA sequences causing marked plasmid structural instability in S. coelicolor, but not in S. lividans, are also located in this region.     

Heterogeneity in direct cytotoxic function of L3T4 T cells. TH1 clones express higher cytotoxic activity to antigen-presenting cells than TH2 clones

In the process of generating culture supernatant from T cell clones, with anti-CD3 antibodies and the B lymphoma A20 as APC, a striking difference in the stimulation of TH1 and TH2 clones was observed, i.e., TH2 clones produced higher levels of lymphokines than TH1 clones. This prompted us to test the hypothesis that differential killing of APC (thus the removal of stimuli) by T cells led to differential T cell activation. By studying a panel of five TH1 and seven TH2 clones, it was demonstrated that TH1 clones mediated significantly higher levels of cytotoxicity toward A20 cells in the presence of soluble anti-CD3 antibody (as opposed to immobilized anti-CD3). Although T cell clones could, when activated with immobilized anti-CD3, produce lymphokines cytotoxic to A20 cells, experiments in which lymphokine production was blocked indicated that T cell clones, in the presence of soluble anti-CD3, mediated killing of A20 through direct cytotoxicity. A higher level of cytotoxicity, by TH1 compared with TH2 clones, was not restricted to anti-CD3 or a particular target cell type, because it also occurred with Con A- or Ag-dependent killing (a monocyte-macrophage cell line), and LPS blasts. Furthermore, the higher cytotoxic activity of TH1 clones compared with TH2 clones was independent of the stage of T cell activation and was unlikely a result of the length of in vitro culture. High levels of killing of APC led to low levels of T cell activation, the significance of which may be as a negative feedback mechanism in the immune response. Other biologic relevancies of higher cytotoxic activity in TH1 vs TH2 cells were also discussed.     

Purification of the microsomal Ca2+-ATPase from rat liver

Summary The Ca²⁺-ATPase from rat liver microsomes has been solubilized in Triton X-100 and purified to homogeneity by ficollsucrose treatment, column chromatography with agarose-hexane adenosine 5-triphosphate Type 2, and high pressure liquid chromatography (HPLC). The purified enzyme obtained by this sequential procedure exhibited a 183-fold increase in specific activity. After ficoll-sucrose treatment, the activity of the Ca²⁺-ATPase was stable for at least two weeks when stored at –70°C. In SDS-polyacrylamide gels, several fractions from HPLC chromatography showed a single band at a position corresponding to a molecular weight of about 107 kDa. This value is consistent with the molecular weight of the phosphoenzyme intermediate of endoplasmic reticulum (ER) Ca²⁺-ATPase. Further characterization of the ER Ca²⁺-ATPase was performed by western immunoblots. Antiserum raised against the 100-kDa sarcoplasmic reticulum (SR) Ca²⁺-ATPase cross-reacted with the purified Ca²⁺-ATPase from rat liver ER membranes.