Examination of Exhaustive Cloning Attempts Reveals that C. elegans piRNAs, Transposons, and Repeat Sequences are Efficiently Cloned in Yeast, but not in Bacteria

Frontiers in Genetics

Or eSagy¹  Ron eShamir¹  Oded eRechavi¹ 

[1] Tel Aviv University;

关键词: C.elegans;    Lateral gene transfer;    repetitive elements;    piRNAs;    bactera;    PIWI-interacting small RNAs;   

DOI  :  10.3389/fgene.2014.00275

来源: DOAJ

【 摘 要 】

Genome sequencing requires insertion of random fragments of the sequenced organism’s DNA into a unicellular host, most often E. coli bacteria. This manipulation was found in the past to be analogous to naturally occurring horizontal gene transfer, and moreover has proved valuable to understanding toxicity of foreign genetic elements to E. coli. Sequencing of the C. elegans genome was similarly achieved via DNA transformation into E. coli. However, numerous attempts have proven a significant percentage of the genome unclonable using bacteria, although clonable via yeast. We examined the genomic segments that were notin bacteria butin yeast, and observed that, in line with previous hypotheses, such sequences are more repetitive on average compared with the entire C. elegans genome. In addition, we found that these gap-sequences encode significantly more for DNA transposons. Surprisingly, we discovered that although the vast majority of the C. elegans genome isin bacteria (77.5%), almost all the thousands of sequences that encode for PIWI-interacting small RNAs, or 21U-RNAs (91.6%) wereonly in yeast. These results might help understanding why most piRNAs in C.elegans are physically clustered on particular loci on chromosome IV. In worms and in a large number of other organisms, piRNAs serve to distinguish Self from Non-Self sequences, and thus to protect the integrity of the genome against foreign genetic elements, such as transposons. We discuss the possible implications of these discoveries

【 授权许可】

Unknown