Djikeng A, Agufa C, Donelson J E, Majiwa P A
International Livestock Research Institute (ILRI), Nairobi, Kenya.
Gene. 1998 Oct 9;221(1):93-106. doi: 10.1016/s0378-1119(98)00427-2.
Previous molecular genetic studies on the African trypanosome have focused on only a few genes and gene products, the majority of which are concerned with surface antigenic variation; consequently, an insignificant number of the genes of this organism have been characterized to date. In order to: (1) identify new genes and analyze their expression profile, (2) generate expressed sequence tags (ESTs) for derivation of a physical map of the trypanosome genome, and (3) make available the partial sequence information and the corresponding clones for general biomedical research on the parasite, we have performed single-pass sequencing of random, directionally cloned cDNAs from a bloodstream form Trypanosoma brucei rhodesiense library. Analysis of 2128 such ESTs sequenced so far in this study showed significant similarities [BLASTX P(n)-value < 10(-4), and a match > 10 amino acid residues] with proteins whose genes have been described in diverse organisms including man, rodents, kinetoplastids, yeasts and plants. A number of the ESTs encode homologues of proteins involved in various functions including signal reception and transduction, cell division, gene regulation, DNA repair and replication, general metabolism, and structural integrity. Although some of these genes may have been expected to be present in the African trypanosomes, the majority of them had not previously been described in these organisms. A large proportion, 768 individual ESTs (36%, representing 385 different transcripts), had a significant homology with genes described in organisms other than the African trypanosomes; however, 15% of the ESTs were from genes already described in trypanosomes. Among the ESTs analysed were 462 distinct known genes, only 77 of which have been described in T. brucei. Approximately 52% of the ESTs did not show any significant homology with the sequences in any of the public domain databases.
以往对非洲锥虫的分子遗传学研究仅聚焦于少数几个基因及其产物，其中大多数与表面抗原变异有关；因此，迄今为止，该生物体中已被鉴定特征的基因数量微不足道。为了：（1）鉴定新基因并分析其表达谱，（2）生成表达序列标签（EST）以推导锥虫基因组的物理图谱，以及（3）提供部分序列信息和相应克隆用于对该寄生虫的一般生物医学研究，我们对来自布氏罗得西亚锥虫血流形式文库的随机定向克隆cDNA进行了单通道测序。对本研究中迄今测序的2128个此类EST的分析表明，它们与包括人、啮齿动物、动基体、酵母和植物在内的多种生物体中已描述基因的蛋白质具有显著相似性[BLASTX P(n)值<10(-4)，且匹配>10个氨基酸残基]。许多EST编码参与各种功能的蛋白质同源物，包括信号接收和转导、细胞分裂、基因调控、DNA修复和复制、一般代谢以及结构完整性。尽管其中一些基因可能预期存在于非洲锥虫中，但它们中的大多数此前尚未在这些生物体中被描述。很大一部分，即768个个体EST（占36%，代表385种不同转录本）与非洲锥虫以外的生物体中描述的基因具有显著同源性；然而，15%的EST来自锥虫中已描述的基因。在所分析的EST中，有462个不同的已知基因，其中只有77个在布氏锥虫中被描述过。大约52%的EST与任何公共领域数据库中的序列均未显示出任何显著同源性。
