Candidate pheromone receptors of the silkmoth Bombyx mori

Abstract

Communication via specific chemical signals is vitally important for the reproductive behaviour of many species. The first identified sex-attractant pheromone was bombykol from the silkmoth Bombyx mori. This female-released signalling compound is perceived by the male moth with extreme sensitivity and specificity. Antennal sensory cells supposedly respond to individual bombykol molecules and can efficiently distinguish bombykol from highly related structural analogues like bombykal, a second female-released pheromone component. In the four decades since the discovery of bombykol, the Bombyx mori system has continued to serve as an invaluable model system for unraveling the intricacies of chemical communication. The molecular basis for this extraordinary specific recognition of an extraneous compound is still elusive but probably based on specific receptors of the pheromone-responsive cells. In this study, molecular and bioinformatic approaches were employed to search for candidate pheromone receptors of Bombyx mori. A few receptor types were identified that are related to Heliothis candidate pheromone receptors. They were found to be almost exclusively expressed in male antennae, and double in situ hybridization experiments disclosed a characteristic topographic expression pattern that was reminiscent of pheromone-responsive cells. Furthermore, the receptor-expressing cells were closely associated with cells expressing the pheromone-binding protein. Together, the data support the view that the identified receptor types of Bombyx mori are candidate receptors for pheromone components.

Pheromone reception in fruit flies expressing a moth's odorant receptor

“…We expressed in the ab3A neurons the OR BmorOR1, which has been previously isolated from B. mori (7,8) and demonstrated to be sensitive to the pheromone constituents of the silkworm moth when expressed in heterologous noninsect cells (Xenopus oocytes and modified HEK cells) (7,9,10). Here, we tested by single-sensillum recordings the response of BmorOR1 expressed in the olfactory system of another insect.…”

“…The selectivity and sensitivity of the system are so remarkable that minimal structural modifications to pheromone molecules render them inactive (5), whereas a single molecule of the natural product is estimated to be sufficient to activate neurons in male antennae (6). Although odorant receptors (ORs) from the silkworm moth have been isolated (7,8), expressed in heterologous cell systems, and demonstrated to be activated by bombykol and bombykal (9, 10), the molecular basis underlying the extraordinary selectivity and sensitivity of the insect's ''nose'' is still terra incognita. Although the ligands (pheromones) are well defined in moths, these insects are not readily amenable to genetic manipulation.…”

Odor and pheromone detection in Drosophila melanogaster

“…Similar models have been proposed in the moth sex pheromone system, which also utilizes an extracellular binding protein [29,44,56,60]. Similarly, LUSH might serve as a carrier of pheromone molecules in the lymph that delivers the VA cargo to the receptors on the olfactory neuron dendrites [13,33,34]. A third alternative is that the LUSH binding protein and VA pheromone form a unique complex that together functions as the ligand for the odorant receptors on pheromone sensitive neurons [27,28].…”

Alternative splicing produces two transcripts encoding female-biased pheromone subfamily receptors in the navel orangeworm, Amyelois transitella

“…For the Lepidoptera, the first ORs were identified from Bombyx mori and Heliothis virescens through analysis of sequenced genomes (Krieger et al, 2004(Krieger et al, , 2005Sakurai et al, 2004;Nakagawa et al, 2005). Further mining of the B. mori genome led to the identification of 48 ORs, and a subfamily, grouped by relatedness, contained putative pheromone receptors from both B.mori and H.virescens (Wanner et al, 2007).…”

“…Subsequently, members of this subfamily have been referred to as male-biased sex pheromone receptor clade (Jordan et al, 2009), sex pheromone receptor subfamily (Miura et al, 2009(Miura et al, , 2010Wanner et al, 2010), pheromone receptors (Patch et al, 2009;Große-Wilde et al, 2010), and male-specific OR subfamily (Mitsuno et al, 2008). To gain a better understanding of how lepidopteran sex pheromones work at the molecular level, research to identify and characterize pheromone receptors in males has been the topic of much research (Krieger et al, 2004(Krieger et al, , 2005Sakurai et al, 2004;Nakagawa et al, 2005;Große-Wilde et al, 2007Wanner et al, 2007Wanner et al, , 2010Mitsuno et al, 2008;Jordan et al, 2009;Miura et al, 2009Miura et al, , 2010Patch et al, 2009;Xu et al, 2012). However, some members of the pheromone receptor subfamily are also activated by plant kairomones (Jordan et al, 2009;Bengtsson et al, 2014), indicating that not all of these ORs respond to pheromones.…”