Cloning and sequencing of a putative acetylcholinesterase cDNA from Boophilus microplus (Acari: Ixodidae).

Using a strategy based on degenerate primers derived from acetylcholinesterase (AChE) from other species, we cloned and sequenced a putative AChE cDNA from the southern cattle tick, Boophilus microplus (Canestrini). The sequence has a high degree of homology to sequences of AChE from other species reported in the GenBank. The open reading frame of 1,689 bp, corresponding to a deduced sequence of 563 amino acids, has conserved regions and features shared by the AChE family, necessary for its catalytic activity. No differences were found in the putative cDNA sequences from organophosphorus acaricide (OP) resistant and susceptible strains. The results suggest that this putative AChE gene is not involved in resistance to OP compounds as a mutated gene in the resistant strain studied. However, differences were detected, with a probe derived from this cDNA, in DNA fragments after digestion of genomic DNA from different strains with restriction nucleases. This indicates polymorphism in this gene in B. microplus.