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

Autor(es): Wang Z H,Fallon A M


Resumo: 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 1 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 approximately 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.


Palavras-Chave: Cell line; Gene amplification; Methotrexate; LINE elements; Zebedee


Imprenta: Insect Biochemistry and Molecular Biology, v. 28, n. 8, p. 613-623, 1998


Identificador do objeto digital: 10.1016/S0965-1748(98)00030-7


Descritores: Aedes aegypti - Cell ; Aedes aegypti - DNA ; Aedes aegypti - Molecular Structure ; Aedes aegypti - Pathogenesis


Data de publicação: 1998