Warren T, Pasternak J J
Department of Biology, University of Waterloo, Ontario, Canada.
Nucleic Acids Res. 1988 Nov 25;16(22):10833-47. doi: 10.1093/nar/16.22.10833.
Digestion of genomic DNA from the nematodes Panagrellus silusiae and Ascaris lumbricoides with restriction endonuclease BamH1 releases a 0.7 kilobase (kb) fragment. The 0.7 kb fragment from both nematodes was cloned onto E. coli plasmid pUC19. Using representative clones as DNA hybridization probes, it was found that (i) the BamH1 fragments cross-hybridize; (ii) a ladder-effect with multiples of 0.7 kb was evident in both species after hybridization to genomic DNA and (iii) the genomic copy number of BamH1 elements is 150 and 195 for P. silusiae and A. lumbricoides respectively. DNA sequence analysis of the inserts, AL700-1 and PS700-1, revealed nucleotide blocks with over 85% similarity. No open reading frames are present in either DNA fragment. Neither fragment hybridizes to genomic DNA from Caenorhabditis elegans. Northern blot hybridization indicated that the 0.7 kb element is transcribed into poly(A)(-)-RNA in P. silusiae; but, is not transcribed in adult Ascaris muscle. Thus, P. silusiae and A. lumbricoides share a homologous, tandemly arrayed, moderately repetitive DNA family.
用限制性内切酶BamH1消化线虫类的小杆线虫（Panagrellus silusiae）和蛔虫（Ascaris lumbricoides）的基因组DNA，会释放出一个0.7千碱基（kb）的片段。来自这两种线虫的0.7 kb片段被克隆到大肠杆菌质粒pUC19上。以代表性克隆作为DNA杂交探针，发现：（i）BamH1片段交叉杂交；（ii）与基因组DNA杂交后，在这两个物种中均明显出现了0.7 kb倍数的阶梯效应；（iii）小杆线虫和蛔虫的BamH1元件的基因组拷贝数分别为150和195。对插入片段AL700 - 1和PS700 - 1进行DNA序列分析，发现核苷酸块的相似度超过85%。两个DNA片段中均不存在开放阅读框。两个片段均不与秀丽隐杆线虫（Caenorhabditis elegans）的基因组DNA杂交。Northern印迹杂交表明，0.7 kb元件在小杆线虫中转录为聚腺苷酸（poly(A)(-)）RNA；但在成年蛔虫肌肉中不转录。因此，小杆线虫和蛔虫共有一个同源的、串联排列的、中度重复的DNA家族。
