膜脂与植物的抗寒性

低温是限制植物分布及其生物产量的重要环境因素,也是危害农业生产的主要自然灾害之一。从１７７８年Ｂｉｅｒｋａｎｄｅｒ报导８种植物在１－２℃低温下死亡现象至今,已有许多科学工作者对植物的寒害机理进行了研究,并提出了“生理干旱”（Ｓａｃｈｓ,１８６４）、“饥饿”（Ｍｏｌｉｓｃｈ,１８９６）、“代谢失调”和“毒物积累”等假说。这些假说从不同角度反映了植物发生冷害原因,但都有一定的片面性。随后的一些研究者对植物的几种冷害生理反应出现的时间顺序进行了比较研究,指出有毒物质积累和代谢活动失调都不是冷害的原初反…     

配体与受体相互作用诱导的膜蛋白构象变化WGA与GPA作用对膜蛋白构象的影响

用ＦＴＩＲ、ＣＤ、微量ＤＳＣ和ＳＴＭ、ＡＦＭ等研究重组脂质体,血影和完整红细胞在配体与膜受体相互作用下膜蛋白构象改变以及纳米水平上膜表面蛋白的形貌、结果表明ＷＧＡ可诱导重组脂质体膜、血影膜和完整红细胞膜蛋白发生一定的不同的构象变化,红细胞及其膜的热力学行为变更,以及红细胞膜表面蛋白的可能交联。     

伴刀豆球蛋白A和层粘连蛋白与膜受体结合下膜分子运动及微丝组装变化的比较

研究伴刀豆球蛋白A和层粘连蛋白分别与小鼠腹腔巨噬细胞膜受体结合下引起细胞膜分子运动的变化和对微丝组装的影响.结果表明,伴刀豆球蛋白A和层粘连蛋白作用下均导致膜表面蛋白分子的侧向扩散速率减慢,膜脂流动性降低,加快膜内微丝组装并使微丝含量增加.两配体作用下引起细胞上述反应有相似性.     

天花粉蛋白与膜脂相互作用的研究

天花粉蛋白（ＴＣＳ）在≥２．２２μｍｏｌ／Ｌ时能引起大豆磷脂脂质体内含物释放,Ｃａ＾２＋对这种释放有一定的促进作用,低ＰＨ值也能促进ＴＣＳ与脂质体的作用;将ＴＣＳ与细细胞一起保温;当ＴＣＳ终浓度达１４．７μｍｏｌ／Ｌ时能损伤红细胞膜,产生溶血作用;ＴＣＳ还能作用于红细胞血影膜,改变其脂双层的不对称性。     

伴刀豆球蛋白A和层粘连蛋白与膜受体结合下膜分子运动及微丝组装变化的比较

研究伴刀豆球蛋白A和层粘连蛋白分别与小鼠腹腔巨噬细胞膜受体结合下引起细胞膜分子运动的变化和对微丝组装的影响.结果表明,伴刀豆球蛋白A和层粘连蛋白作用下均导致膜表面蛋白分子的侧向扩散速率减慢,膜脂流动性降低,加快膜内微丝组装并使微丝含量增加.两配体作用下引起细胞上述反应有相似性.     

细胞的跨膜信号传递系统及细胞膜受体

多细胞有机体中每个细胞的活动不是孤立进行的，在众多细胞之间存在着一套复杂的跨膜信号传递系统（Ｔｒａｎｓｍｅｍｂｒａｎｅｓｉｇｎａｌｔｒａｎｓｄ－ｕｃｔｉｏｎｓｙｓｔｅｍ），使细胞间能相互联系和沟通，协调不同组织器官中各个细胞的代谢、分泌、分化和增殖等...     

脱血红素细胞色素c与膜结合及插膜时的构象研究

应用特殊的单分子层样品制备技术,分别制备了与中性、酸性磷脂膜结合的和完全插膜的鸡心脱血红素细胞色素c样品,并运用圆二色谱(CD)、表面衰减全反射Fourier变换红外光谱(ATR-FTIR)对膜上蛋白的构象进行了鉴定.研究结果表明,蛋白在与膜结合及插入阶段的构象是不同的,膜界面性质的不同也会对蛋白的构象产生不同的诱导,在酸性磷脂DSPG膜表面,该蛋白是以α螺旋和β折叠混合的构象形式结合;而在中性磷脂DSPC膜表面是以β折叠为主的构象形式结合.插入 DOPG单分子层内时则是 α螺旋为主的构象形式.     

铝胁迫对水稻膜脂组分和含量的影响

以‘日本晴’水稻为试验材料,研究铝胁迫对水稻幼苗生长的影响,及铝胁迫下其根系和功能叶片中脂质含量及组分的变化。结果表明Al处理显著抑制了水稻根尖的伸长和生长,降低了植株的生物量以及叶绿素含量。铝胁迫后,半乳糖脂含量变化显著,根和叶中的单半乳糖甘油二酯(MGDG)和双半乳糖甘油二酯(DGDG)含量均降低;而磷脂(PL)及硫代异鼠李糖甘油二酯(SQDG)的含量在根中表现为上升,在叶中则显著降低。此外,根和叶中的脂肪酸不饱和度均降低。由此可见,铝胁迫引起水稻膜脂组分和含量的变化,这种变化可能是铝抑制植物生长的重要原因之一。     

伴刀豆球蛋白A与巨噬细胞膜上受体作用下膜变形性及细胞吞噬能力变化

本文采用图像分析、相差显微、生物活性测定等技术,研究ConA与巨噬细胞膜受体结合后对细胞行为与功能的影响. ConA与受体结合后巨噬细胞膜面积增大、变形性和吞噬能力增强、细胞产热量增加,表明细胞膜结构与功能发生变化.本实验是将图像分析技术用来研究相对图像采集速度要慢得多的活细胞特性的一次成功尝试.     

DPH标记细胞膜的动力学与膜脂流动性的荧光偏振校正测量

用稳态荧光技术测得经过校正的荧光成分,由此算出用DPH标记的细胞膜的偏振度。方法是作荧光偏振值在随时间变化的曲线,将其外推至零标记时间求出该时间的荧光偏振值。用此法测定了艾氏腹水癌细胞的膜流动性。结果表明流动性比用整个细胞测得之值小,说明膜脂的有序程度和包装密度比胞浆中的脂大。实验结果和用三房空模型分析所得的理论值符合较好,提示荧光探剂的标记过程主要受分子扩散所控制。     

THE FINE STRUCTURE AND IMMUNOLOGICAL LABELING OF THE ACHROMATIC MITOTIC APPARATUS AFTER DISRUPTION OF CELL MEMBRANES

After treatment of HeLa and L cells with vinblastine sulfate the material of microtubules (tubulin) was reorganized into (a) large paracrystals (PC) of tightly packed tubules; (b) smaller aggregates of tubules with greater diameter whose walls are constituted from well defined, helically arranged morphological subunits; and (c) microtubules associated with helices of polyribosomes of uniform size. All of these structures survived disruption of cellular membranes by means of a nonionic detergent. Following a thorough stripping of membranes there remained a subcellular fraction sedimenting at 1,500 g for 15 min, in which were contained nuclei, centrioles, and the above mentioned microtubular elements, maintained as a complex of organelles by an interconnecting network of 80 Å microfibrils. As a result of membrane disruption it was possible to localize precisely in the electron microscope the binding of ferritin antibody conjugates. Specific labeling at the surface of PC and microtubule aggregates could be demonstrated. This result was substantiated by means of the immunoperoxidase method of labeling the PC. A concentrated deposit of ferritin was also found in the vicinity of centrioles and related structures, the annuli of the nuclear pore complex and the annulate lamellae. However, the specificity of the label on these organelles remains questionable because ferritin, albeit in lower concentration, was also present on them in control preparations reacted with preimmune sera.     

THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR : V. THE INFLUENCE OF THE THICKNESS OF DRIED COLLODION MEMBRANES UPON THEIR ELECTROMOTIVE BEHAVIOR

1. Experiments were carried out to decide whether or not the electromotive properties of dried collodion membranes depend upon their thickness. 2. A number of dried collodion membranes of varying thickness, 3–160 µ, were prepared from collodion preparations of different electrochemical activity. The characteristic concentration potentials across them were measured and the means of these values determined for each thickness. 3. The characteristic concentration potentials across dried collodion membranes are a function of their thickness. The thinnest membranes yield in all cases the lowest concentration potentials; increasingly thicker membranes give increasingly higher potential values, until a constant value is reached which is characteristic of the particular collodion preparation used. With electrochemically active collodion, characteristic concentration potentials approaching the thermodynamically possible maximum are obtained with membranes of only 10 µ thickness, thinner membranes giving appreciably lower values. With two rather inactive commercial collodion preparations the characteristic concentration potential increases from about 30 mv. for membranes 3 µ thick to about 42 mv. for 20 µ membranes; still thicker membranes do not show a significant increase in the potential values. With a highly purified collodion preparation the constant maximum value was found to be about 32 mv., 4 µ thick membranes giving only about 22 mv. 4. These results do not support the homogeneous phase theory as applied to the dried collodion membrane. They are readily compatible with the micellar-structural theory. Several special possible cases of the latter as applied to the dried collodion membrane are discussed.     

THE BEHAVIOR OF CHLORIDES IN THE CELL SAP OF NITELLA

1. A method is given for determining the chloride content in a drop (less than 0.03 cc.) of the cell sap of Nitella. 2. Chlorides accumulate in the sap to the extent of 0.128 M; this accumulation can be followed during the growth of the cell. The chloride content does not increase when the cell is placed for 2 days in solutions (at pH 6.2) containing chlorides up to 0.128 M. 3. The exosmosis of chlorides from injured cells can be followed quantitatively. When one end of the cell is cut off a wave of injury progresses toward the other end; this is accompanied by a progressive exosmosis of chlorides.     

钆和镱对人红细胞膜脂及膜蛋白的作用

利用荧光偏振,自旋标标顺磁共振波谱和激光拉曼技术研究了钆和镱对人红细胞膜结构和功能的影响。结果表明,低浓度的Ｇｄ３＋（０．５μｍｏｌ／Ｌ）对（Ｎａ＋＋Ｋ＋）－ＡＴＰ酶和Ｍｇ２＋－ＡＴＰ酶有轻微的激活作用,而随着其浓度的增大,则明显抑制酶的活性,Ｇｄ３＋与Ｙｂ３＋和人红细胞膜作用后,降低膜脂流动性,并使膜蛋白酰胺Ｉ＇－α螺旋振动强度减弱．     

细胞表面凝集素受体定量分析的一个新公式和实验方法的探讨

本文提出一个描述细胞与多价凝集素反应的平衡关系式和用紫外分光光度法测定游离凝集素浓度求受体数量及其与凝集素的亲合常数的方便方法.使用此法求得小鼠乳腺癌MA_(602)腹水细胞表面的ConA受体数量和亲合常数.