Abstract:

Tyramine is a biological polyamine, which serves important functions as neurotransmitters, neuromodulators and neurohormone of the central nervous system. It participates in the regulation of various behavior and physiological processes in insects. For example, tyramine and its receptor genes are involved in the regulation of learning and memory in the animals. In this study, the full-length cDNA sequences of the tyramine receptor genes (Actyr1 and Actyr2) of the Chinese honeybee, Apis cerana cerana, were cloned and sequenced for the first time. Their expression patterns were examined in different tissues by qRT-PCR and localized in the head by in situ hybridization with digoxigenin (DIG)-labeled RNA probes. The full-length cDNAs of Actyr1 and Actyr2 are 1241 bp (GenBank accession no. KC814693) and 1270 bp (GenBank accession no.KC814693) in length and encode 297 amino acids and 399 amino acids, respectively. qRT-PCR results showed that the expression levels of both Actyr1 and Actyr2 were the highest in the head, followed by the abdomen, then the antennae and the lowest in the thorax. The expression level in the head was significantly higher than that in other tissues. Moreover, in situ hybridization showed that the expression of Actyr1 and Actyr2 genes were mainly localized to the Kenyon cells of the mushroom bodies and cells around the antennal lobes. These observations suggest that some interactions between these two genes in certain cells could be important in regulating various biological functions, such as learning and memory, in the honeybee.

Key words: Apis cerana cerana, tyramine receptor genes, molecular cloning, expression analysis