Analysis of a conserved duplicated tRNA gene in the mitochondrial genome of blowflies Ana Cla ´udia Lessinger * , Ana Carolina M. Junqueira, Fa ´bio F. Conte, Ana Maria L. Azeredo Espin Laborato ´rio de Gene ´tica Animal, Centro de Biologia Molecular e Engenharia Gene ´tica (CBMEG), Universidade Estadual de Campinas (UNICAMP), C.P. 6010, CEP 13083-875, Campinas, SP, Brazil Received 14 January 2004; received in revised form 20 May 2004; accepted 21 June 2004 Available online 18 August 2004 Received by G. Pesole Abstract The mtDNA control region (CR) and flanking genes of the blowflies Chrysomya albiceps , Chrysomya megacephala and Chrysomya chloropyga (Calliphoridae) were characterized. The most unusual feature found was the presence of duplicated tRNA sequences corresponding to trnI and a portion of trnQ. The partially duplicated trnQ was very likely a pseudogene since most of the sequence of the typical insect trn Q gene was missing. In contrast, the trn I gene had a conserved primary sequence following the duplication event and may represent a functional copy. These results demonstrate the plasticity of the mtDNA molecule in Chrysomya , especially for tRNA genes and the adjacent control region sequences. D 2004 Elsevier B.V. All rights reserved. Keywords: mtDNA; Control region; Rearrangement; Molecular evolution; Chrysomya 1. Introduction Rearrangements and duplications have been reported in animal mtDNA and occur independently of the coding or non-coding nature of the duplicated sequences and of the relative position in the mitochondrial genome, although duplication events associated with or adjacent to control region (CR) sequences are more frequent (Boore, 1999). Duplicated genes are rarely observed among mitochondrial DNAs (mtDNAs) and the disintegration of supernumerary genes is typically rapid. The structural organization of the insect mtDNA control region (also known as the A+T-rich region) has been reviewed by Zhang and Hewitt (1997). The lack of structural conservation of the control region and adjacent genes, even among closely related species, limits the use of universal insect mtDNA primers and requires special care in the interpretation of homologous elements in comparative analyses. Lessinger and Azeredo-Espin (2000) described conserved and variable sequences arranged in specific structural domains in the mtDNA control region of myiasis-causing flies (myiasis is an infestation produced by dipterous larvae). Comparative analysis led to the identification of eight conserved sequence blocks (CSB) in control region sequences near to the clustered trn I, trn Q and trn M (IQM) and highly variable sequences near the rrn S. 0378-1119/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.gene.2004.06.041 Abbreviations: A, adenine; bp, base pair(s); C, cytosine; CIR, Chrysomya intergenic region; CSB, conserved sequence block(s); CR, control region; G, guanine; IQM, clustered trnI, trnQ and trnM genes; mtDNA, mitochondrial DNA; nad1–6, NADH dehydrogenase subunits 1– 6; rrnS, small ribosomal RNA; T, thymine; trn or tRNA, transfer RNA gene; trnQ, glutamine trn; trnI , isoleucine trn; trnM, methionine trn; trnF, phenylalanine trn; trnP, proline trn; trnS, serine trn; trnY , tyrosine trn; U, uridine. * Corresponding author. Tel.: +55 19 3788 1141; fax: +55 19 3788 1089. E-mail address: lessinge@unicamp.br (A.C. Lessinger). Gene 339 (2004) 1 – 6 www.elsevier.com/locate/gene