Intragenomic variation in ITS2 rDNA in the louse of humans, Pediculus humanus: ITS2 is not a suitable marker for population studies in this species

Publication Type:Journal Article
Year of Publication:2002
Authors:N. P. Leo, Barker S. C.
Journal:Insect Molecular Biology
Pagination:651 - 657
Date Published:2002
Keywords:animals, Australia, Base Sequence, China, dna, geography, humans, Introns, Japan, Lice Infestations/parasitology, Molecular Sequence Data, Pediculus, phylogeny, polymerase, Research Support, Non-U.S. Gov't, sequence, U.S.A., variation

The two internal transcribed spacers (ITS) of ribosomal DNA are often used as markers of populations of insects. We studied the ITS2 of the head lice and body lice of humans, to determine whether this gene is a suitable marker of populations of these insects. ITS2 sequences were amplified by PCR from lice from four different countries: Australia, China, Japan and the USA. Direct cycle-sequencing of some of these PCR products gave equivocal nucleotide chromatograms. This indicated that some lice had more than one ITS2 sequence, so we cloned PCR products from these lice. Temperature gradient gel electrophoresis (TGGE) revealed that 50 of the 67 clones we screened had different nucleotide sequences. All lice had several ITS2 types, including those with unequivocal chromatograms. A phylogenetic tree of 15 different ITS2 sequences showed that the sequences from individual lice were not monophyletic. We conclude that the ITS2 is not a useful marker of populations for Pediculus humanus.

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