Isolation of a cDNA for an octopamine-like, G-protein coupled receptor from the cattle tick, Boophilus microplus

Octopamine is a biogenic amine neurotransmitter of invertebrates that binds to a G-protein coupled receptor that has seven transmembrane domains. Form amidine pesticides like amitraz are highly specific agonists of the octopam ine receptor. Amitraz is used extensively to control the cattle tick, Booph ilus microplus, and many other ticks but now there are strains of ticks tha t are resistant to amitraz. We have isolated a cDNA from the cattle tick, B . miciroplus, that belongs to the biogenic amine family of receptors. The p redicted amino acid sequence from this cDNA is most similar to octopamine r eceptors from insects. The nucleotide sequence of this gene from amitraz-re sistant and amitraz-susceptible cattle ticks was identical. Thus, a point m utation/s did not confer resistance to amitraz in the strains we studied. A lternative explanations for resistance to amitraz in B. microplus are discu ssed. (C) 1999 Elsevier Science Ltd. All rights reserved.