The Preliminary Analysis Of An Expressed Sequence Tags (ESTs) Database From The Venom Glands Of Lachesis muta (Bushmaster Snake)

Junqueira-de-Azevedo, I.L.M.¹; Ching, A.T.C.¹; Faria, F.¹; Ho, P.L.¹ and Diniz, M.R.V.²

1-Centro de Biotecnologia, Instituto Butantan - São Paulo SP; 2-FUNED – MG, BRAZIL

The Lachesismuta snake is the largest Crotalinae (pitviper) species in the world and an endangered species from tropical forests, whose venom possesses several features from Bothrops and Crotalus genus. In order to produce a global panorama of the transcriptional activity of snake venom glands and to correlate with its venom composition, we constructed a plasmid cDNA library from Lachesismuta muta venom gland mRNA to generate an Expressed Sequence Tags (ESTs) database. The venom gland was collected from a dead animal found in captivity. ESTs are DNA sequences obtained from either 5´ or 3´ ends of cDNA clones randomly chosen which are used in the characterization of gene expression (transcriptome) of target tissues. Good quality sequences were obtained from 693 independent clones, with an average size of 442 bp. The ESTs were clustered, generating 463 unique sequences which were further analyzed by similarity comparison with molecular databases. These analyses revealed the putative identification of 277 distinct gene products. Toxin sequences correspond to 25% of all transcripts (29 clusters), being the bradykinin-potentiating peptides the far most abundant transcript (16%). We also found transcripts corresponding to metalloproteinases, serinoproteinases, C-lectins, PLA2s and L-aminoacid oxidases.  Besides the toxins, a full-length clone coding a PLA2 inhibitor was also found, suggesting the presence of such inhibitors on the venom glands. Among the 240 clusters matching cellular proteins, the major part represents molecules involved in gene and protein expression, reflecting the specialization of this tissue for toxin synthesis. An ADAM metalloproteinase similar to mammalian sequences could be identified and may correspond to a new toxin. Unusual sequences of retrotransposable elements previously found in B. insularis database were also expressed in L. muta. In conclusion, our L. muta dbEST is the first effort to identify cDNA sequences from this species and the preliminary analysis of the partial transcriptome carried out until now revealed some features of its venom composition and venom gland physiology.

Support: FAPEMIG, FAPESP, CNPq and Fundação Butantan.

Correspondence to: ijuncaze@usp.br