CLONING AND CHARACTERIZATION OF CDNAS THAT CODE FOR NA-CHANNEL-BLOCKING TOXINS OF THE SCORPION CENTRUROIDES-NOXIUS HOFFMANN()

With the purpose of studying the organization and characteristics of t he genes that code for toxins present in the venom of the Mexican scor pion, Centruroides noxius Hoffmann (CnH), we prepared a lambdagt11 cDN A library from the venom glands. Using specific oligodeoxyribonucleoti des (oligos) designed according to known amino acid (aa) sequences of CnH toxins (STox), we detected several positive clones, determined the ir nucleotide (nt) sequences and deduced their aa sequences. A compara tive analysis of these sequences with previously reported STox reveale d that CnH cDNAs code for a family of very similar STox. The cDNA codi ng for a known STox, II-10, was cloned. Additionally, three other comp lete (new) nt sequences were obtained for cDNAs encoding peptides simi lar to STox 1 from CnH or variants 2 and 3 from Centruroides sculptura tus Ewing. Southern blot genomic DNA analysis showed a minimum size of approximately 600 bp as EcoRI fragments for elements of this family. PCR amplifications of CnH genomic DNA and hybridization of PCR product s with specific probes indicated that the genomic structural regions t hat code for these genes do not contain introns, or at least not large introns.