Feagin J E, Drew M E
Seattle Biomedical Research Institute, Washington 98109-1651, USA.
Exp Parasitol. 1995 May;80(3):430-40. doi: 10.1006/expr.1995.1055.
The malaria parasite Plasmodium falciparum has two extrachromosomal DNAs, a 6 kb reiterated element which appears to be the mitochondrial DNA and a 35 kb circular DNA of unknown function. Examination of relative steady-state transcript abundance during parasite development in the erythrocyte shows that transcripts of 6 kb element protein-coding genes are least abundant in the ring and early trophozoite stages and most abundant in late trophozoites and schizonts, while transcripts from the RNA polymerase subunits of the 35 kb DNA, also least abundant in ring stage, are relatively similar in abundance in succeeding stages. The fragmented rRNAs of the 6 kb element appear to be constitutively abundant except for an increase in the schizont stage, while rRNAs from the 35 kb DNA are least abundant in early trophozoites and most abundant in schizonts. Thus the relative abundance of organelle transcripts alters during the erythrocytic portion of the P. falciparum developmental cycle. These alterations may reflect the relative importance of the roles played by organelle gene products in different life cycle stages.
疟原虫恶性疟原虫有两个染色体外DNA，一个6 kb的重复元件，似乎是线粒体DNA，还有一个35 kb的环状DNA，其功能未知。对红细胞内寄生虫发育过程中相对稳态转录本丰度的检测表明，6 kb元件蛋白质编码基因的转录本在环状体和早期滋养体阶段丰度最低，在晚期滋养体和裂殖体阶段丰度最高，而35 kb DNA的RNA聚合酶亚基的转录本在环状体阶段也丰度最低，在后续阶段丰度相对相似。6 kb元件的片段化rRNA似乎一直丰度较高，除了在裂殖体阶段有所增加，而35 kb DNA的rRNA在早期滋养体中丰度最低，在裂殖体中丰度最高。因此，在恶性疟原虫发育周期的红细胞阶段，细胞器转录本的相对丰度会发生变化。这些变化可能反映了细胞器基因产物在不同生命周期阶段所起作用的相对重要性。
