Similarities to a LINE element shared by Anopheline and Culicine mosquitoes map to the distal end of dihydrofolate reductase amplicons in Aedes albopictus mosquito cells

Zhong Hui Wang, Ann M. Fallon

Research output: Contribution to journalArticlepeer-review

Abstract

To extend our understanding of amplicon structure in methotrexate- resistant Mtx-5011-256 Aedes albopictus mosquito cells, we examined a series of cosmids containing genomic DNA corresponding to the unique 3'-end of the Type I dihydrofolate reductase amplicon. Cosmid pWED118 contained five EcoRI fragments ranging from 2 to 5 kb (A, B, C, F, G) that hybridized to cDNA from methotrexate-resistant cells. Of these, fragments B and F hybridized weakly to first-strand cDNA from sensitive cells and shared considerable sequence identity. Fragment G occurred twice in the map of pWED118; one copy mapped within a 10 kb BssHII core fragment from the Type I amplicon and a second copy mapped downstream in the 48 kb BssHII core fragment. Hybridization signals among fragments contained in overlapping cosmids suggested that a branch point defining two or more subtypes of the Type I amplicon occurs within or near the 10 kb BssHII genomic DNA fragment. A 1.8 kb sequence common to fragments B and F included an ~0.4 kb region that shared sequence similarities with a LINE element from Aedes aegypti and with a repeated sequence from Anopheles gambiae. In addition, these elements shared amino acid similarity to a reverse transcriptase from the nematode, Caenorhabditis elegans. Shared sequence between Aedes and Anopheles elements supports the hypothesis that an ancestral LINE-like element was active in mosquito genomes prior to the divergence of the subfamilies Culicinae and Anophelinae. The presence of homologies to LINE-like elements near a branch point in the dihydrofolate reductase amplicon is consistent with a possible role of repeated sequences in amplicon shortening.

Original languageEnglish (US)
Pages (from-to)613-623
Number of pages11
JournalInsect Biochemistry and Molecular Biology
Volume28
Issue number8
DOIs
StatePublished - Aug 1998

Bibliographical note

Funding Information:
This work (contribution # 98-1-17-0010) was supported by grants AI 20385 and HD 24869 from the NIH and by the University of Minnesota Experiment Station, St. Paul, MN.

Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.

Keywords

  • Cell line
  • Gene amplification
  • LINE elements
  • Methotrexate
  • Zebedee

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