Studies on the encystation of Entamoeba

对内阿米巴的包囊机制进行了初步探讨。从生化和形态上进行了研究。所获得的结果如下所示。通过对侵染艾美耳球虫包囊DNA含量的荧光分析，发现从单核包囊到四核包囊的核分裂过程中，每个包囊的总DNA恒定在4C左右，表明包囊成熟过程中存在减数分裂。入侵棘球藻单核包囊的染色体数为10-12，成熟的四核包囊为5-6。这些结果也提示了包囊过程中的减数分裂。但尚未检测到联会复合体。Verrcarin A是微管形成的抑制剂之一，对内阿米巴SPP的核分裂和包囊有强烈的抑制作用。作为一种新的阿米巴杀菌剂的应用还有待进一步研究。激活依赖于钙的代谢途径如钙离子载体(A23187)和TPA的药物对侵袭埃希氏菌的包囊有很强的抑制作用，而激活依赖于cAMP的途径的药物对侵袭埃希氏菌的包囊无明显影响。新分离自日本猕猴的大肠杆菌在无糖条件下具有包囊活性，在侵袭性肠杆菌中也有包囊活性。然而，我们试图诱导溶组织埃希氏菌包囊，但未获成功。通过与H-ras探针杂交，表明入侵E.inadens具有与ras相关的序列。

The encystation mechanism of Entamoeba spp. was investigated biochemically and morphologically. The results obtained are shown below.1. By epifluorometric assays of DNA contents in E. invadens cysts, it was revealed that total DNA per each cyst during nuclear divisions from uni- to tetra-nucleated cysts was constant to be 4C, which suggested the presence of meiosis in the cyst maturation.2. The numbers of chromosomes in E. invadens were counted to be 10-12 in uni-nucleated cysts, and 5-6 in matured tetra-nucleated cysts. These results also suggested the meiotic division in the encystation. However, synaptonemal complex could not be detected yet.3. Verrcarin A, one of the inhibitors of microtubule formation tested, strongly inhibited the nuclear division and encystation of Entamoeba Spp. Applications as a new amebicidal agent should be further investigated.4. The agents activating Ca^<2+>-dependent metabolic pathways such as Ca^<2+> ionophore (A23187) and TPA strongly inhibited the encystation of E. invadens, whereas those activating cAMP-dependent pathways had no significant effects.5. E. coli newly isolated from Japanese monkeys had encystation activity in the glucose-free medium as well as E. invadens. However, our attempts to induce the encystation of E. histolytica were unsuccessful.6. By hybridizing with H-ras probe, it was shown that E. invadens has a ras-related sequence.