CONCANAVALIN A-INDUCED AGGLUTINATION AND BINDING OF CON A TO THE DIFFERENTIATING CELLS OF DICTYOSTELIUM DISCOIDEUM

Changes in agglutinability of Dictyostelium discoideum cells with Concanavalin A (Con A) during the course of development were investigated. The agglutinability of the cells was assayed under conditions where no spontaneous cell agglutination occurred. It was found that there was a progressive decrease in Con A-induced agglutinability during development: a decrease to half from exponentially growing cells to preaggregation cells, and to sixth in disaggregated slug cells. Pronase-BAL treatment of preaggregation cells did not enhance their agglutinability with Con A. The amounts of sites available for binding Con A were determined with preaggregation and slug cells. Cells were incubated at 4°C and in the presence of NaN₃ to avoid possible endocytosis of Con A. No significant differences in numbers of Con A-binding sites per unit area of cell surface was detected among preaggregation cells, those treated with pronase and BAL and cells disaggregated from slugs by similar treatment. It was thus concluded that the decrease in Con A-induced agglutinability during development is not attributable to changes in the numbers of Con A-binding sites.     

THE VISUALIZATION OF CONCANAVALIN A BINDING SITES IN PURKINJE CELL SOMATA AND DENDRITES OF RAT CEREBELLUM

The localization of concanavalin A (Con A) binding sites in Purkinje cell somata and dendrites has been studied using a peroxidase labeling technique. In the somata, the nuclear, Golgi, and endoplasmic reticulum (ER) membranes are rich in Con A binding sites. The hypolemmal cisternae, which are continuous with the ER from the soma and throughout the dendritic tree of Purkinje cells, are also rich in Con A binding sites. Other cisternae seen in these dendrites do not bind detectable amounts of Con A. The results suggest that a cisternal system, rich in carbohydrate, may be continuous from the nuclear envelope to distal dendritic segments of Purkinje cells. Such a system could play a role in the movement of materials from Purkinje somata to dendrites.     

BINDING OF CONCANAVALIN A TO THE SURFACE OF STARFISH FOLLICLE CELLS AND PRODUCTION OF 1-METHYLADENINE

Starfish follicle cells, treated with concanavalin A (Con A), continued to produce 1-methyl-adenine (1-MeAde), an inducer of starfish oocyte maturation, after rinsing with artificial seawater (ASW). On the other hand, they ceased to produce the substance if treated with methyl α-Dmannoside (αMM). These cells produced again 1-MeAde when re-stimulated with Con A after removal of αMM. An optical study with fluorescein revealed that Con A bound to the cells was not dissociated by rinsing with ASW, but was removed if the cells were treated with αMM. These results suggest that continuous binding of Con A to the surface of the follicle cells is essential for the production of 1-MeAde.     

Con A诱导植物原生质体凝集作用的研究

不同种的植物表现出有不同的凝集反应。随着温度及Con A浓度的提高,凝集作用增强,并且低温(5～6℃)对裸大麦叶原生质体的凝集作用的影响随温度恢复而可以消失。处于无生长素条件下而脱分化的烟瘤、生长素诱导脱分化的烟草愈伤组织以及处于正常分化状态的叶,三者原生质体间的凝集反应有明显差异。而植物激素IAA、6-BA及GA_3对凝集作用的影响表明,GA_3能引起凝集效应减弱。     

外源激素对番茄质膜结合植物凝集素的影响

番茄愈伤组织培养于附加不同激素的 MS 培养基上。经过3次继代培养后,分别从这些愈伤组织分离原生质体,并使之与植物凝集素 ConA 结合。再从原生质体制备质膜。比较在相同膜蛋白含量条件下,质膜上结合~(125)I-ConA。结果表明:在含有2,4-D 的培养基上番茄培养细胞的质膜结合 ConA 的能力保持在很高的水平上。其它生长物质和激动素对细胞表面特性的影响各不相同。     

LEUCOCYTE BINDING TO THE UTERINE EPITHELIAL CELL SURFACE DURING LECTIN-INDUCED DECIDUALIZATION

Intra-uterine injection of the lectin Concanavalin A (ConA) on day 5 of pseudopregnancy induced a rapid and persistent infiltration of leucocytes into the rat uterine stroma. Although the infiltration of leucocytes was seen along the entire length of the uterine horn, areas of stromal oedema, indicative of decidualization (as indicated by a positive Pontamine Sky Blue reaction), were only associated with regions in which leucocytes had crossed the uterine epithelium and were present in the uterine lumen. Ultrastructural evaluation of the interaction of the luminal leucocytes with the apical surface of the uterine epithelium appeared strikingly similar to that of the blastocyst and the uterine epithelium during normal implantation. It is proposed that leucocytes, induced by ConA, may initiate a decidual response in a manner analogous to that of the blastocyst through surface epithelial interaction.     

伴刀豆蛋白A与活细胞膜作用的图像分析和多元统计

用图像分析与多元统计研究伴刀豆蛋白A(ConA)与活巨噬细胞膜受体结合时膜变形性随作用时间和ConA浓度的定量变化。结果表明膜面积增大,增大速率与ConA速度呈正相关。ConA浓度加大,膜园形系数减小,变形性增加,此等变化反应了细胞的活化。     

SUGAR-CONTAINING COMPOUNDS ON THE CELL SURFACES OF MARINE DIATOMS MEASURED USING CONCANAVALIN A AND FLOW CYTOMETRY

Some diatom exudates may remain attached to the exterior cell surface, potentially altering cell stickiness and affecting important aspects of the diatom's ecology such as aggregation rates and grazing rates. We measured the accumulation of cell-surface sugar-containing compounds by labeling cultured marine diatoms with fluorescent-tagged sugar-binding lectins and measuring the fluorescence associated with each cell using flow cytometry. The binding of FITC-labeled concanavalin A (FITC-ConA), a lectin that binds to glucose and mannose residues, varied 5-fold among different diatom species in exponential growth (on a per-cell basis) and 2–3-fold within a given species in different physiological states. Although transparent exopolymer particles followed a simple accumulation curve over time in batch culture, FITC-ConA. cell^-1 did not follow the same pattern, suggesting that surface sugar accumulation is not driven simply by the accumulation of such particles in the medium. For Thalassiosira pseudonana (Hustedt) Hasle and Heimdal (3H clone), the amount of sugar-containing compounds on the cell surface increased transiently as growth rate slowed in early stationary phase under both N and Si limitation. For Chaetoceros neogracile (Schuett) van Landingham, FITC-ConA. cell^-1had a strong inverse relationship with growth rate across several Si-limited batch culture experiments. Both results suggest some biological mediation of cell-surface sugar-containing compounds. Our study reveals the great potential for using lectin binding to investigate cell-surface sugars on diatoms. Lectins allow us to investigate noninvasively the role of cell-surface sugar-containing compounds in modifying cell stickiness and aggregation, as well as the partitioning of exuded phytoplankton carbon. We suggest that cell-surface sugar accumulation may be related to diatom stickiness, based on a correlation between our FITC-ConA measurements and stickiness estimates in the literature on several of the species we studied.     

THE BINDING OF TRIETHYLTIN TO RAT BRAIN MYELIN

—A high affinity binding site for triethyltin was found in rat brain myelin with an affinity of approx 6·6 × 10⁵m ⁻¹ at pH 7·5. Competitive binding studies showed that triethyl-lcad had about the same affinity and trimethyltin 30 times lower affinity than triethyltin. Hexachlorophane and 3,5-diiodo-4′-chlorosalicylanilide did not prevent triethyltin binding to rat brain myelin. Since triethyltin, hexachlorophane and 3,5-diiodo-4′-chlorosalicylanilide all produce similar oedematous lesions in the brain of rats, whereas triethyl-lead and trimethyltin do not, it is concluded that the high affinity triethyltin binding site either is not involved or is not the only factor in oedema production.     

BINDING OF MUSCARONE BY EXTRACTS OF HOUSEFLY BRAIN: RELATIONSHIP TO RECEPTORS FOR ACETYLCHOLINE

The supernatant fluid fraction isolated by centrifugation from a homogenate of heads of houseflies bound muscarone reversibly, with a binding constant of 2·4 × 10^?6m and an amount of 70 nmol/g of protein. Studies with 28 drugs demonstrated strong blockade by the 17 cholinergic agents, suggesting both nicotinic and muscarinic characteristics in the mode of binding. The binding appeared to involve acetylcholine receptors.     

人胃癌不同周期细胞膜表面ConA受体的分布与侧向运动

本文研究了人胃低分化粘液性腺癌细胞MGC 80-3不同周期时相中ConA受体的分布与侧向运动。MGc 80-3细胞经同步化培养,用F-ConA标记。被标记细胞中G_1、S和G_2期呈不连续的分布,但它们之间又存在显著的差异。M期呈较均匀的强荧光分布(与其它时相细胞比较)。荧光漂白恢复方法测定ConA受体复合物侧向运动表明:各个周期时相之间不仅运动方式不同,而且运动速率也有显著差异。M期与G_1期主要表现出扩散型运动;而S期与G_2期表现为流动型运动。G_1期的扩散系数大干M期的;S期的流动速率大于G_2期的。但可动分子百分比以G_2期最高。这些结果表明了ConA受体的动力学性质。它受到细胞周期的调节。     

蚕豆保卫细胞原生质体质膜ABA结合蛋白与气孔对ABA敏感性的关系

在测定蚕豆(Vicia faba L.)保卫细胞原生质体质膜ABA结合蛋白的解离常数(Kd)和最大结合容量的基础上,进一步研究了几种因子(pH、光)对Kd和最大结合容量的影响。结果显示:pH并不改变结合蛋白的Kd值,而仅影响每个原生质体结合的分子数;光、暗处理的结果表明,光可使结合蛋白的Kd值增大,每个原生质体结合的ABA分子数减少,而暗处理可使结合蛋白的Kd值减小及每个原生质体结合的分子数增多,说明黑暗可提高气孔保卫细胞对ABA的敏感性,而光可以降低气孔保卫细胞对ABA的敏感性。因此,光、暗可以通过调节ABA结合蛋白的Kd值来调节气孔对ABA的敏感性。     

刀豆球蛋白A对Ehrlich腹水癌细胞的膜电位和表面电荷的影响

本文报告用荧光探剂diS-C_3—(5)和细胞电泳技术研究刀豆球蛋白A(ConA)作用于Ehrlich腹水癌细胞引起的膜电位和表面电荷的变化.ConA与细胞膜相应受体结合,导致在膜上的diS-C_3-(5)的荧光强度增加,表明细胞去极化.经用缬氨霉素诱导的钾扩散电位校正,与光学讯号变化相应的膜电位变化约是20mv.细胞经G毒毛旋化苷处理后,ConA引起的去极化程度比未处理过的细胞大.ConA作用于Ehrlich腹水癌细胞使细胞电泳迁移率变小.表明细胞表面负电荷数目减少.本文对这些变化的可能机制和相互关系进行了讨论.     

抗霉素A抑制琥珀酸细胞色素c还原酶的动力学特征

用邹承鲁关于酶不可逆抑制动力学方法研究了抗霉素A(AA)对琥珀酸细胞色素c还原酶(SCR)抑制的动力学行为,发现AA与SCR的结合表现为快慢两相动力学特征。本文就此两相动力学行为的意义进行了分析,得出功能状态SCR是双体酶的结论,并提出了描写AA与SCR结合的动力学机制。     

THE RELATIONSHIP OF THE REFERRING PHYSICIAN TO THE PSYCHIATRIST

The relationship of the referring physician to the psychiatrist is believed to be of a different order than that of most physicians to one another. Certain facts are postulated as playing a role in this somewhat difficult relationship and examples from actual practice are offered as evidence. Among possible points of discord are mentioned: The length and cost of psychotherapy and relative youth of the specialty, the referring physician''s hostile feelings toward it, and the unhelpful attitude of certain psychiatrists.     

THE RELATIONSHIP OF THE REFERRING PHYSICIAN TO THE PSYCHIATRIST

Tumors of the adrenal glands produce hormones which cause a variety of symptoms and signs including high blood pressure, excessive growth of hair on the body and precocious sexual development. By recently developed tests, it has been possible to differentiate high blood pressure due to these tumors from hypertension due to other causes. Removal of these tumors will often alleviate changes caused by them. Localization of the tumor and appraisal of the condition of the contralateral gland should be carried out preoperatively if possible. In this, several kinds of roentgen studies are helpful. Infusions of drugs during operation can be used to control the blood pressure which otherwise would vary widely. During a ten-year period (1942 to 1951) there were observed at the Los Angeles County General Hospital 100 proved cases of non-secreting and secreting primary neoplasms of the adrenal glands. In addition, there were three cases of Cushing's syndrome due to bilateral adrenal cortical hyperplasia, and ten probable cases (four, pheochromocytomas; five, Cushing's syndrome; one, adrenogenital syndrome) in which operation was not done.     

THE ISOELECTRIC POINT OF RED BLOOD CELLS AND ITS RELATION TO AGGLUTINATION

1. The movement of normal and sensitized red blood cells in the electric field is a function of the hydrogen ion concentration. The isoelectric point, at which no movement occurs, corresponds with pH 4.6. 2. On the alkaline side of the isoelectric point the charge carried is negative and increases with the alkalinity. On the acid side the charge is positive and increases with the acidity. 3. On the alkaline side at least the charge carried by sensitized cells is smaller and increases less rapidly with the alkalinity than the charge of normal cells. 4. Both normal and sensitized cells combine chemically with inorganic ions, and the isoelectric point is a turning point for this chemical behavior. On the acid side the cells combine with the hydrogen and chlorine ions, and in much larger amount than on the alkaline side; on the alkaline side the cells combine with a cation (Ba), and in larger amount than on the acid side. This behavior corresponds with that found by Loeb for gelatin. 5. The optimum for agglutination of normal cells is at pH 4.75, so that at this point the cells exist most nearly pure, or least combined with anion and cation. 6. The optimum for agglutination of sensitized cells is at pH 5.3. This point is probably connected with the optimum for flocculation of the immune serum body.     

腹腔注射ConA对鲤鱼表皮粘液细胞的影响

腹腔注射Ｃｏｎ Ａ （伴刀豆球蛋白Ａ） 后, 鲤鱼腮粘膜上皮、口腔粘膜上皮和皮肤的粘膜细胞数量明显增多, 且在上皮的深层也出现部分粘膜细胞, 但其形态、大小无明显变化。