The poly(A)+ mRNA isolated from the venomous terminal segments of the scorpion Buthotus judaicus was reversed transcribed into cDNA. PCR amplification of the cDNA in presence of oligonucleotide primers prepared on basis of the known amino acid sequence of the depressant insect toxin II yielded a 125 bp long product. This fragment was cloned and its sequence determined. The deduced amino acid sequence has revealed a complete homology with the amino acid sequence of the toxin. This clone was used to probe a Northern blot resolving the poly(A)+ and poly(A)− fractions derived from the scorpion. An organ specific 360 nucleotide transcript which might be the processed product of a 4̃.0 kb precursor was elucidated. This cDNA clone may pave the way for a molecular genetic approach to study the structure-function relationship of scorpion selective insect toxins.
