Levasseur P J, Meng Q, Bouck G B
Department of Biological Sciences (M/C 066), University of Illinois at Chicago 60607-7060.
J Eukaryot Microbiol. 1994 Sep-Oct;41(5):468-77. doi: 10.1111/j.1550-7408.1994.tb06044.x.
Alpha- and beta-tubulin cDNA were selected from a Euglena lambda gt11 expression library, recloned and either sequenced (alpha-tubulin cDNA) or hybridized to Euglena RNA and DNA (alpha- and beta-tubulin cDNA). RNA for hybridization was extracted at 30 minute intervals after flagellar amputation and quantitated for cDNA binding. Unlike previous reports on most other flagellates, no net increase in either alpha- or beta-tubulin RNA could be detected during regeneration--suggesting steady state or constitutive tubulin RNA synthesis. Incubation of the cDNA with genomic DNA after restriction digestion produced patterns of hybridization consistent with the presence of one to two kinds each of the alpha- and beta-tubulin genes. The deduced amino acid sequence of the alpha-tubulin cDNA was more than 90% identical to the alpha-tubulins of Trypanosoma, Chlamydomonas, Naegleria, Tetrahymena and higher plants. The carboxy terminus of the alpha-tubulin cDNA and the previously sequenced beta-tubulin of Euglena showed greatest identity to the carboxy terminus of the tubulins from Trypanosoma brucei. The sequence data for alpha- and beta-tubulins of Euglena provides direct evidence for the similarity of two gene products from euglenas and trypanosomes and adds support to earlier suggestions that these organisms are phylogenetically related.
从眼虫属λgt11表达文库中筛选出α-和β-微管蛋白cDNA，进行亚克隆，然后对α-微管蛋白cDNA进行测序，对α-和β-微管蛋白cDNA与眼虫属RNA和DNA进行杂交。鞭毛切除后每隔30分钟提取用于杂交的RNA，并对cDNA结合进行定量分析。与之前关于大多数其他鞭毛虫的报道不同，在再生过程中未检测到α-或β-微管蛋白RNA的净增加，这表明微管蛋白RNA的合成处于稳态或组成型。限制性消化后，将cDNA与基因组DNA一起温育，产生的杂交模式与α-和β-微管蛋白基因各存在一到两种的情况一致。α-微管蛋白cDNA推导的氨基酸序列与锥虫、衣藻、耐格里属、四膜虫和高等植物的α-微管蛋白有90%以上的同源性。α-微管蛋白cDNA的羧基末端和之前测序的眼虫属β-微管蛋白与布氏锥虫微管蛋白的羧基末端具有最大的同源性。眼虫属α-和β-微管蛋白的序列数据为眼虫属和锥虫属两种基因产物的相似性提供了直接证据，并支持了这些生物体在系统发育上相关的早期观点。
