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71.
Mu-jin Tang Shao-ling Zeng Jian-wu Chen Yong-xia Shi Wei Xu Mei-jin Yuan Yi Pang 《Insect Science》2003,10(4):221-229
A series of plasmids were constructed to examine the effects of p19 and orf1‐orf2 genes from Bacillus thuringiensis on Cyt1Aa synthesis and inclusion formation. The plasmids expressed the cyt1Aa gene along with either p19 or orf1‐orf2, or each of them coordinatively with p20 in the acrystalliferous strain of B. thuringiensis subsp. israelensis 4Q7. No effect on the expression of Cyt1Aa protein was found when P19 or Orf1‐Orf2 co‐expressed with Cyt1Aa. However, when including p20 gene, the constructs with p19 or orf1‐orf2 gene produced lower yield of Cyt1Aa proteins than without p19 or orf1‐orf2 gene. Electron microscopy observation and bioassay showed that P19 and Orf1‐Orf2 have no influence on the crystal size and toxicity of Cyt1Aa protein. It is presumed that P19 and Orf1‐Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis. 相似文献
72.
The surface pressure-area (-A) isotherms ofN-hexadecyl-8-hydroxy-2-quinolinecarboxamide (HHQ) monolayers at an air-water interface on subphases with different pH values were investigated. The monolayer of HHQ was expanded and unstable on acidic subphases, while it was condensed and stable on basic subphases. The acid-base equilibrium of HHQ was investigated in an aqueous dioxane solution and at the air-water interface. The association-dissociation of HHQ with H+ ions in the interfacial region was very different from that in the aqueous dioxane solution. Some information regarding the packing density, phase transition and degree of ionization of the head group under different experimental conditions has been obtained. 相似文献
73.
浙江海岛盐生植被研究Ⅱ──天然植被类型及开发利用 总被引:4,自引:0,他引:4
天然盐生植被是海岛盐生植被的主体,类型丰富,分布广泛,在海岛植被的研究及开发利用中占据重要地位。目前,天然盐生植被的分类尚无统一标准与系统。本文根据作者1990~1993年在浙江海岛用样方法(H.VonPost,1851;陈彦卓,1965)测定的样地数据,参照《中国植被》的分类方法,根据群落的外貌与结构、生态地理、动态和种类组成等特征进行分类,其中对群系级单位侧重于种类组成,并采用建群植物的重要值(J.T.CurtisandR.P.McIntosh,1951)作为分类的定量指标。据此,浙江海岛天然盐生植被可划分为3个植被型、8个群系组、18… 相似文献
74.
75.
质体非均衡分裂时,其传递和分配情况复杂,重组状态多。本文分析了突变质体在各种分配情况下得到的概率,条件概率、联合概率和一细胞至少含m_0个突变质体的概率公式及计算示例。讨论了它们在生物学中的重要意义。 相似文献
76.
本文利用小鼠大脑机械损伤模型及体外培养的胶质细胞,采用同位素渗入法观察了细胞介素及其抗体对胶质细胞增生的影响。结果表明:体外培养时TNF-α在浓度为10~200u/ml培养液时均能促进胶质细胞增生(P<0.05),IL1-β在浓度为5~200u/ml培养液时能促进胶质细胞增生,TNF-α+IL1-β其促进胶质细胞增生作用更强烈,TNF-α抗体能完全阻断TNF-α的促增生作用,部分阻断TNF-α+IL1-β的促增生作用。在体实验时,IL1-β及TNF-α的作用与离体时相似,IL1-β及TNF-α亦能促进胶质细胞增生,二者共同作用时促细胞增生作用更强。以上结果提示,外源性TNF-α及IL1-β能促进中枢神经损伤后胶质细胞增生且具有协同作用。 相似文献
77.
采用HPIEC应用CM交换柱分离纯化E.coli工程菌表达的rIL-2,与空气氧化复性相比较,又有1倍以上的变性rIL-2在色谱过程中得到复性,且溶液pH影响rIL-2的复性和纯化效果:pH7.0时rIL-2复性率高于pH8.0时,但纯度明显低于pH8.0时分离的rIL-2. 相似文献
78.
利用RT-PCR技术分离低密度脂蛋白受体基因cDNA,将长为2605bp的cDNA插入质粒pJN6,并经全序列测定证实,该序列与已报道序列相比,存在两个变异碱基,即第754位C→T,和1654位的G→A,这两个变异碱基并不改变编码的氨基酸,利用LDL受体基因cDNA中的ClaⅠ片段作为探针,检测到LDL受体基因上外显子8的StuⅠ位点是个限制性片段长度多态性位点。所克隆的cDNA含有可译框架的全部密码,因此可作为基因表达材料。 相似文献
79.
Chang WC Shyu WJ Shi GY Lin MT Jen CJ Wing LY Tang MJ Wu HL 《Journal of biomedical science》1996,3(1):59-66
Treatment of cultured bovine carotid artery endothelial cells with 0.1 µM human plasmin has been reported to induce a receptor-mediated short burst of arachidonate release, which is a pertussis toxin-sensitive and extracellular calcium-dependent reaction. Plasmin-induced calcium influx in cells was significantly inhibited by pretreatment with pertussis toxin, indicating that the former was coupled with a pertussis toxin-sensitive guanosine 5-triphosphate (GTP)-binding protein. Plasmin significantly induced the formation of lysophosphatidylcholine but not lysophosphatidylethanolamine. A cellular phospholipase A2 with an arachidonyl specificity at the sn-2 position of phosphatidylcholine, which required submicromolar calcium, was identified as a cytosolic phospholipase A2 by immunoblot analysis. By a cell-free enzyme activity assay and immunoblot analysis, plasmin was found to induce a translocation of the cytosolic phospholipase A2 from the cytosol to the membrane. Taken together, the results suggest that plasmin bound to its putative receptor and activated a GTP-binding protein coupled to calcium influx channel, followed by translocation and activation of cytosolic phospholipase A2 in endothelial cells. 相似文献
80.
The allometry of algal respiration 总被引:7,自引:0,他引:7
For 30 years, study after study has shown that respiration ratesincrease as {small tilde}0.75 of body size for organisms rangingfrom protozoans to mammals. However, a number of studies suggestedthat the respiration-size relationship for algae may be a rareexception to this general rule. Algal respiration may be almostproportional to cell size, such that the slope of the respiration-sizerelationship is closer to unity. The present study examinedthe effect of cell size and taxon on phytoplankton respiration,using data collected from the literature. To this end, we collecteda data set of 178 observations of algal respiration and cellsize representing six divisions-chlorophytes. chrysophytes,cyanophytes, euglenophytes, pyrrophytes and rhodophytes. Therelationship between respiration (R, in p1 O2 cell1 h1)and cell carbon content (C, in pg C cell1) is describedas R = 0.030C0 93 and the exponent is significantly >3/4.When we expressed cell size in terms of volume, the exponentdecreased to 0.88 but this is still significantly >3/4. Amongthe six divisions studied, chlorophytes, euglenophytes and rhodophytesseemed to differ significantly in their respiration-size relationshipfrom other taxa. However, euglenophytes and rhodophytes havesuch small size ranges that no meaningful relationships canbe developed for those groups alone. The chlorophyte respiration-sizerelationship has obvious patterns in its residuals which mayindicate that significant sources of error were not controlledin these heterogeneous data. Thus, for the present, the generalmodel seems most appropriate for the prediction of respirationrates of phytoplankton. 相似文献