Molecular and cellbiological studies on gametocytogenesis of a malaria parasite, Plasmodium falciparum

疟原虫恶性疟原虫配子细胞发生的分子和细胞生物学研究

基本信息

批准号：
12670230
负责人：
KAWAMOTO Fumihiko
金额：
$ 2.18万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Induction mechanism of gametocytogenesis in a malaria parasite, Plasmodium falciparum was investigated cell-biologically and molecularly, using wild isolates.1. Induction of gametocytogenesis in wild isolates : Induction methods of gametocytogenesis was studied, using wild isolates collected from Myanmar and Indonesia.Gametocytogenesis was observed when the parasite density reached to ca. 5% and then they were cultivated at 3-4 times higher concentrations of RBC than normal culture condition. All wild isolates adapted for in vitro cultivation were capable in forming gametocytes, and their transformation rates reached to 50-70%.2. Induction ofgametocytogenesis by glucose deficiency : As gametocytogenesis was induced by cultivation at higher RBC concentration, it was speculated that nutrient deficiency, particularly glucose, may play important role in triggering this phenomenon. In fact, addition of glucose into the medium inhibited the induction of gametocytogenesis. Furthermore, addition of 2-deoxy glucose was capable in inducing it under a normal culture condition, although a great decrease ofparasitaemia was observed. These results indicated that glucose deficiency might play an important role in inducing gametocytogenesis.3. Trials of induction ofgametocytogenesis in established strains : Using FCR-3 and K-l strains, induction of gametocytogenesis was examined as like in wild isolates, but no gametocyte was formed, suggesting that important genes for induction of gametocytogenesis might be deleted in these strains.4. Identification of master gene(s) for induction of gametocytogenesis : Using a subtraction method between mRNA isolated from gametocyogenesis-induced and non-induced parasites, master gene(s) which may regulate gametocytogenesis was investigated. However, all clones obtained after the subtraction were only heat shock protein genes, and expected genes, such as cAMP-dependent kinases, were not detected.

利用野生菌株，对恶性疟原虫配子细胞发生的诱导机制进行了细胞生物学和分子学研究。 1．野生分离株中配子细胞发生的诱导：使用从缅甸和印度尼西亚收集的野生分离株研究了配子细胞发生的诱导方法。当寄生虫密度达到约10％时观察到配子细胞发生。 5%，然后在比正常培养条件高3-4倍的红细胞浓度下培养。所有适合体外培养的野生菌株均能形成配子体，其转化率达到50-70%。2．葡萄糖缺乏诱导配子细胞发生：由于配子细胞发生是通过在较高红细胞浓度下培养来诱导的，因此推测营养物缺乏，特别是葡萄糖，可能在引发该现象中发挥重要作用。事实上，向培养基中添加葡萄糖抑制了配子细胞发生的诱导。此外，添加2-脱氧葡萄糖能够在正常培养条件下诱导它，尽管观察到寄生虫血症大大减少。这些结果表明，葡萄糖缺乏可能在诱导配子细胞发生中起重要作用。 3．已建立菌株诱导配子细胞发生的试验：使用FCR-3和K-1菌株，与野生分离株一样检查配子细胞发生的诱导，但没有形成配子细胞，表明这些菌株中可能缺失了诱导配子细胞发生的重要基因。4．用于诱导配子细胞发生的主基因的鉴定：使用从配子细胞发生诱导的和非诱导的寄生虫分离的mRNA之间的差减法，研究了可以调节配子细胞发生的主基因。然而，扣除后获得的所有克隆都只是热休克蛋白基因，并没有检测到预期的基因，例如cAMP依赖性激酶。