CELL AGGREGATION IN DICTYOSTELIUM DISCOIDEUM
CELL AGGREGATION IN DICTYOSTELIUM DISCOIDEUM
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DOI：
10.1016/0012-1606(61)90038-0
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发表时间：
1961-01-01
影响因子：
2.7
通讯作者：
RAPER, KB
中科院分区：
文献类型：
--
作者：
KONIJN, TM;RAPER, KB
盘基网柄藻粘阿米巴小种群的聚集能力，即。例如，以形成假原质团，包括在洗涤或纯化的琼脂上原位发育的种群，其中通过限制营养物（细菌）来限制粘阿米巴的生长，以及收获、洗涤并以已知数量以预定密度沉积在洗涤或纯化的琼脂上的预生长的粘阿米巴种群，所述洗涤或纯化的琼脂的组成不同并以不同方式制备。调查集中于盘基网柄藻（菌株NC-4）及其某些亚株的典型培养，但也包括该物种的其他9个分离物，这些分离物在起源上与NC-4无关。聚集能力被认为是相似的，在所有这些小种群生长和测试在相同的条件下。聚合能力试验的条件对所得结果有很大影响。聚集的主要因素包括：（1）每单位面积基质上粘阿米巴的数量和密度之间存在着关键的关系;（2）在未分布的培养物中营养耗尽后或在微滴水或盐水中预生长的种群沉积在琼脂上后，细胞必须保持在合理的接近度内数小时;（3）通过洗涤从正常琼脂中去除某些未识别的物质，这些物质允许植入的液滴扩散并加强细胞分散;和（4）琼脂凝胶的最佳重构或制备，或两者。研究人员发现，100-150只或更少的粘液阿米巴的聚集能力与作者所能识别的任何特殊类型的细胞无关。相反，这种能力被认为是由于营养耗尽后整个种群内出现的生理变化，一方面，或植入一个预生长的种群。不寻常的大粘液变形虫，被认为是代表所谓的“I细胞”在现有的文献中报道，偶尔观察到，但他们没有发生在任何合理的确定比例，其不同的特点似乎表明没有共同的起源。最后，它们在绝大多数测试群体中的完全缺失未能支持它们代表对盘基网柄藻中假原质团形成具有特殊意义的独特细胞类型的观点。
The capacity of small populations of myxamebas of Dictyostelium discoideum to aggregate, i. e., to form pseudoplasmodia, was investigated under contrasting cultural and environmental conditions, including populations developed in situ on washed or purified agar where growth of myxamebas was restricted by limiting the nutrient (bacteria), and populations of pregrown myxamebas that were harvested, washed, and deposited in known numbers at predetermined densities upon washed or purified agar varying in composition and prepared in different ways. The investigations centered upon the type culture of Dictyostelium discoideum (strain NC-4) and certain substrains from it, but included also nine other isolations of this species unrelated to NC-4 in point of origin. Aggregative capacity was found to be similar in all these when small populations were grown and tested under like conditions. The conditions under which tests of aggregative capacity were made profoundly influenced the results obtained. Factors of primary importance to aggregation seemed to include the following: (1) the existence of a critical relationship between the number of myxamebas and their density per unit area of substrate; (2) the necessity for cells to remain within reasonable proximity over a period of several hours subsequent to nutrient depletion in undistributed cultures or after deposition on agar of pregrown populations in minute drops of water or saline; (3) the removal by washing from normal agar of certain unidentified substances that permit spreading of implanted drops and accentuate cell dispersal; and (4) the optimal reconstitution or preparation, or both, of the agar gel. The ability of a small population of 100-150 myxamebas, or fewer, to aggregate was found to be independent of any special type of cell recognizable by the writers. Rather this capacity is thought to result from physiological changes emergent within the population as a whole following nutrient depletion, on the one hand, or implantation of a pregrown population on the other. Unusually large myxamebas, believed to represent the so-called "I-cells" reported in existing literature, were occasionally observed; but they did not occur in any reasonably definite ratio, and their diverse characteristics seemed to suggest no common origin. Finally, their total absence from the great majority of test populations fails to support the notion that they represent a unique cell type of special significance to pseudoplasmodium formation in Dictyostelium discoideum.