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United States Department of Agriculture

Agricultural Research Service

Title: Precise Limitation of Concerted Evolution to Orf's in Mosquito Hsp82 Genes

Authors
item Benedict, M - UNIVERSITY OF ARIZONA
item Levine, B - UNIVERSITY OF ARIZONA
item Ke, Z - EMORY UNIV BIO DEPT
item Cockburn, Andrew
item Seawright, Jack

Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 22, 1995
Publication Date: N/A

Interpretive Summary: Future mosquito control efforts will rely on genetic control systems derived through research in genetic engineering. Part of the genetics research program at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL is aimed at describing the genes that will be important tools for use in genetic control strategies. In this study of the heat-shock protein, Hsp82, in Anopheles albimanus, an important malaria mosquito in much of Central and South America, we discovered two identical genes for the protein. The genes were oriented in a head-to-head arrangement; more importantly, however, we found that the genetic machinery in the cells can repair mutations of the genes through a process called "gene conversion". Portions of these heat-shock genes can be used to develop genetic systems for the control of insect pests. Our work on the description of the Hsp82 genes, and the gene conversion system, is important because it provides basic information on genetic control of insects and because it may be useful for mosquito control in the future.

Technical Abstract: Two Hsp82 genes were isolated from the malaria vector anopheles albimanus in a single lambda phage clone. The two genes are in a head-to-head arrangement separated by approx. 0.9 kbp. Northern hybridizations and 5' RACE demonstrate that both genes are transcribed, have moderate levels of constitutive transcription, and are also heat-inducible with maximum transcript accumulation occuring after 40 degrees C heat shocks. Both genes have typical heat-shock promoters and conserved intron boundaries in the untranslated leaders. The open reading frames are 99.6% identical differing in only nine silent nucleotide positions in the 2166 bp ORF's. However, precisely outside the ORF's, the flanking DNA of the two genes shows no evidence of common derivation. The high degree of identity between the two ORF's appears to be a result of gene conversion occuring by a process similar to that previously suspected in the A. albimanus Hsp70 genes and several D. melanogaster genes arranged as palindromes. This process probably involves a stem-loop intermediate and is restricted in extent by flanking sequence divergence. These Hsp82 genes clearly demonstrate the extreme precision with which gene conversion can lead to protein-coding-region homogeneity yet allow flanking DNA divergence.

Last Modified: 12/19/2014
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