Identification of a melatonin receptor type 1A gene (AccMTNR1A) in Apis cerana cerana and its possible involvement in the response to low temperature stress.

It is known that melatonin plays an indispensable role in the defense against some environment-induced stresses. The melatonin receptor (MTNR) is also closely linked to the environmental stress response in mammals. However, little is known about the function of the MTNR in insects, including honeybees. In this study, we identified a MTNR from Apis cerana cerana named AccMTNR1A, which contained a typical seven-transmembrane domain common to this family of receptors. A subcellular localization analysis showed that AccMTNR1A was localized in the cytomembrane. Additionally, we found that cold stress apparently boosted AccMTNR1A transcription, indicating that AccMTNR1A possibly connects to the cold stress response. The knockdown of AccMTNR1A attenuated the expression level of some genes associated with the cold stress response, suggesting that AccMTNR1A likely plays an analogous role with these genes during low temperature stress response. Moreover, silencing of AccMTNR1A also suppressed the transcription of some antioxidant genes, prompting the possibility that the response of AccMTNR1A to cold stress response may be related to antioxidant signaling pathways. Collectively, the findings presented here provide evidence that AccMTNR1A may play essential roles in protecting Apis cerana cerana from cold stress.