Mojave rattlesnakes (Crotalus scutulatus scutulatus) lacking the acidic subunit DNA sequence lack Mojave toxin in their venom

The venom composition of Mojave rattlesnakes (Crotalus scutulatus scutulatu s) differs in that some individuals have Mojave toxin and others do not. In order to understand the genetic basis for this difference, genomic DNA sam ples from Mojave rattlesnakes collected in Arizona, New Mexico, and Texas w ere analyzed for the presence of DNA sequences that relate to the acidic (M ta) and basic (Mtb) subunits of this toxin. DNA samples were subjected to P CR to amplify nucleotide sequences from second to fourth exons of the acidi c and basic subunits. These nucleotide sequences were cloned and sequenced. The nucleotide sequences generated aligned exactly to previously published nucleotide sequences of Mojave toxin. All DNA samples analyzed generated p roduct using the basic subunit primers, and aligned identically to the Mtb nucleotide sequence. However, only 11 out of the 14 samples generated a pro duct with the acidic subunit primers. These It sequences aligned identicall y to the Mta nucleotide sequence. The venom from the three snakes whose DNA did not amplify with the acidic subunit primers were not recognized by ant ibodies to Mojave toxin. This suggests that snakes with venom lacking Mojav e toxin also lack the productive nucleotide sequence for the acidic subunit in their DNA. (C) 2001 Elsevier Science Inc. All rights reserved.