Comparative Biochemistry and Physiology Part B 134 (2003) 389–395 1096-4959/03/$ - see front matter  2002 Elsevier Science Inc. All rights reserved. doi:10.1016/S1096-4959(02)00289-0 Molecular characterization of hemoglobin a-D chains from Geochelone carbonaria and Geochelone denticulata land turtles Monica B. Melo *, Silvana Bordin , Adriana S.S. Duarte , Satie H. Ogo , a,b, c a d ˆ Marcio A. Torsoni , Sara T.O. Saad , Fernando F. Costa d a a ´ Department of Clinical Medicine – Hemocentro, School of Medical Sciences, State University of Campinas (UNICAMP), a Cidade Universitaria Zeferino Vaz SyN, Caixa Postal 6198 Campinas, SP, CEP 13083-970, Brazil ´ Department of Physiology, School of Medical Sciences, Santa Casa de Sao Paulo, Sao Paulo, SP, Brazil b ˜ ˜ Department of Physiology and Biophysics, Biomedical Sciences Institute, State University of Sao Paulo (USP), Sao Paulo, SP, c ˜ ˜ Brazil Department of Biochemistry, Biology Institute, State University of Campinas (UNICAMP), Campinas, SP, Brazil d Received 18 June 2002; received in revised form 5 December 2002; accepted 9 December 2002 Abstract In order to help elucidate the evolution of a-globins, the complete cDNA and amino acid sequences of Geochelone carbonaria and Geochelone denticulata land turtles a-D chains have been described. In G. carbonaria, the cDNA is 539 bp with ATG start codon located at position 46, TGA stop codon at position 469 and AATAAA polyadenylation signal at position 520. In G. denticulata, the cDNA is 536 bp with ATG start codon located at position 46, TGA stop codon at position 469 and AATAAA polyadenylation signal at position 517. Both cDNAs codify 141 amino acid residues, differing from each other in only four amino acid residues. When comparing with human Hb a-chain, alterations in important regions can be noted: a110 Ala–Gly, a114 Pro–Gly, a117 Phe–Tyr and a122 His–Gln. There is a high homology between the amino acids of these turtles when compared with chicken a-D chains, progressively decreasing when compared with human, crocodile, snake, frog and fish a-chains. Phylogenetic analysis of a-D chains shows that those of turtles are closer to those of birds than to snakes and lizards.  2002 Elsevier Science Inc. All rights reserved. Keywords: Geochelone carbonaria; Geochelone denticulata; c-DNA library; Evolution; a-D chain; Globin; RACE; Reptiles 1. Introduction Geochelone carbonaria and Geochelone denti- culata belong to the family of Testudinidae and are fully terrestrial turtles, geographically distrib- uted in the Guianas, Colombia, Venezuela and Brazil (Torsoni and Ogo, 1995). Among verte- brates, hemoglobins (Hbs) have been widely used as subject for evolution and molecular adaptation studies due to their highly conserved tridimension- *Corresponding author. Tel.: q55-19-3788-8734; fax: q55- 19-3289-1089. E-mail address: melomb@uol.com.br (M.B. Melo). al structure and biological function, exhibiting a great variation regarding absolute affinities for oxygen and susceptibility to control by metabolic effectors (Petruzzelli et al., 1996). Through the analysis of non-mammalian Hb composition and structure, it has been possible to understand the wide variety of regulatory mechanisms and corre- lation with important amino acid residues, that allow the adaptation of species to the environment (Komiyama et al., 1995; Mylvaganam et al., 1996; Gorr et al., 1998; Shishikura and Takami, 2001). Functional aspects of reptilian Hb have been stud- ied among ectotherms. In the South American land