Abstract
Background: Phoneutria nigriventer spider venom contains several cysteine-rich peptide toxins that act on different ion channels. Despite extensive studies on its venom and description of cDNA sequences of several of its toxin precursors, the gene structure of these toxins remains unknown.Methods:Genomic regions encoding the precursors of three previously characterized P. nigriventer toxins - PnTx1, PnTx2-5 and PnTx4(5-5) - were amplified by PCR using specific primers. PCR fragments were cloned and sequenced. Obtained sequences were compared with their corresponding cDNA sequences.Results:The size of PCR fragments obtained and sequences corresponding to genomic regions encoding for the toxin precursors matched their cDNA sequences.Conclusions:Despite a few nucleotide substitutions in the genomic regions encoding for the toxin precursors when compared with cDNA sequences, the results of the present work indicate that P. nigriventer toxins do not contain introns in their genes sequences.
Highlights
Phoneutria nigriventer spider venom contains several cysteine-rich peptide toxins that act on different ion channels
Using information from cDNA sequences, we designed specific primers in order to amplify genomic regions encoding for the precursors of three well characterized toxins from the spider P. nigriventer, namely PnTx1, PnTx2-5, and PnTx4(5-5)
The results showed that the size of PCR fragments corresponding to amplified genomic DNA (gDNA) encoding for precursor sequences of PnTx1 and PnTx2-5 matched the amplified cDNA fragments, which were expected to be 396 bp and 271 bp, respectively (Figure 1)
Summary
Phoneutria nigriventer spider venom contains several cysteine-rich peptide toxins that act on different ion channels. Phoneutria nigriventer is one of the largest existing spiders from the suborder Araneomorphae (RTA clade; family Ctenidae) and one of the few in the world that can cause harm to humans [1,2]. P. nigriventer venom contains several neurotoxic peptides that act on ion channels and chemical receptors of vertebrates and invertebrates [3] This venom has been studied for over 40 years and cDNA sequences of several toxin precursors have been obtained [4,5,6,7,8,9,10], up to this moment there is no investigation on the genome or even gene structure of any of its toxins. The description of Phoneutria toxins gene structure, as a member of the RTA clade (the most diverse group within spiders), is a relevant contribution to the field
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