New bioassay system for evaluating per cent survival of entamoeba histolytica cysts.
New bioassay system for evaluating per cent survival of entamoeba histolytica cysts.
复制标题
用于评估溶组织内阿米巴包囊存活百分比的新生物测定系统。
作者：
R. Stringer
在高倍显微镜下，排出的溶组织内阿米巴滋养体脱落出半透明的囊壁，很容易与完整的囊壁区分开来。一种新的包囊生物测定系统是基于这样的假设，即空囊代表活着的阿米巴，而完整的包囊代表死亡的阿米巴或不能脱囊的阿米巴。活的阿米巴可以通过在37℃的单相营养介质中孵育来刺激它们外晶。然后，可以从转移到玻片上、盖上盖子并进行显微镜检查的激发培养液滴中的满的和空的形式的计数来计算活孢子虫在种群中的百分比。生物检测系统的独特之处在于，它可以将包囊存活率表示为样本中包囊总数的百分比，并可以将任何测试的结果修正为对照包囊。这一新的生物测定系统已成功地用于评估不同来源的溶组织肠杆菌包囊在不同温度和相对湿度下暴露于卤素消毒剂和储存的能力。将溶组织内阿米巴包囊放入改良的TP-S-1培养液中，37℃孵育10小时后，阿米巴通过包囊壁的裂口存活下来。死的阿米巴仍然埋在囊内。在孵化期后的分泌液的显微镜下，可以清楚地看到空囊囊壁--具有突起的活性滋养体--和含有死亡阿米巴的完整的包囊。图1显示了空囊肿壁与完整囊壁的区别。包囊种群中活体的百分比可以从满(死)和空的数量中计算出来
Excysting Entamoeba histolytica trophozoites shed a translucent cyst wall which can easily be distinguished from the intact cyst under high-dry magnification of a microscope. A new cyst bioassay system is based on the assumption that an empty cyst represents an ameba which was alive and excysted, in contrast to a full cyst which represents a dead ameba or one unable to excyst. Live amebae can be stimulated to excyst by incubating them at 37 C in a monophasic nutrient medium. The percentage of live cysts in a population can then be calculated from a count of the full and empty forms in a drop of the excystation culture which is transferred to a slide, covered with a cover slip, and microscopically ex- amined. The unique aspects of the bioassay system are that it makes it possible for cyst survival to be expressed as a percentage of the total number of cysts in a sample, and for the results from any test to be corrected for control cysts. This new bioassay system has been utilized successfully in studies de- signed to evaluate the ability of E. histolytica cysts from a variety of sources to survive exposure to halo- gen disinfectants and storage at various temperatures and relative humidities. When Entamoeba histolytica cysts are placed in a modified TP-S-1 medium and incubated at 37 C for 10 hr, live amebae excyst through a rupture in the cyst wall. Dead amebae remain entombed within the cyst. Clearly evident in a microscopic view of an aliquant of the excysta- tion culture after the incubation period are empty cyst walls-active trophozoites which have excysted-and full cysts which contain dead amebae. Figure 1 illustrates the ease with which the empty cyst wall can be differentiated from the intact cyst. The per cent of live forms in a population of cysts can be calculated from the number of full (dead) and empty