Research:
The Hofferberth research group employs the tools of organic chemistry to explore biological models in the general area of insect olfaction. Ongoing projects include the elucidation of the chemical basis of interspecies interactions and in vitro characterization of proteins involved in the detection of odorant signals by insects.
Chemical Cues in Mutualistic Insect Associations:
We are working in collaboration with Dr. Ann Fraser, an entomologist at Kalamazoo College, to elucidate the chemical basis of the mutualistic association between the Imperial Blue butterfly (Jalmenus evagoras) and small black ants, Iridomermex ancepts. The association is contingent on female butterflies locating food plants tended by their host ants. Our labs have proposed that olfactory signals allow the butterflies to identify the presence of their host ants and influence their egg laying behavior.
In an effort to understand the olfactory cues sensed by the butterflies, we have collected the blend of volatile compounds produced by a number of ant species of Iridomermex ants and tentatively identified their components by GC/MS. We are in the process of preparing authentic samples of the odors involved to corroborate our tentative identifications and allow biological examination individual components and blends of the synthetic samples.
Characterization of a pheromone binding protein from the Madeira cockroach, Leucophaea maderae (PBPLma):
The biological role of insect pheromone binding proteins (PBP’s) is not well understood. As a class, PBP’s are small (13 – 17 kDa), globular proteins that are secreted in high concentration (~10 mM) in the sensillar lymph that bathes the olfactory neurons. As their name suggests, PBP’s are known to bind pheromones and putatively function to facilitate their interaction with odorant receptor proteins on the surface of the olfactory neuron. Open questions remain about the role of PBP’s in the selection of odors that reach the odorant receptor, the details of their interaction with the odorant receptor, and their role in signal attenuation at high pheromone concentrations. We seek to characterize the pheromone binding protein from Leucophaea maderae in vitro to explore these questions.
Many insects are capable of sensing and distinguishing
pheromone concentrations that vary by 10 orders of magnitude. It has been
proposed that pheromone concentration dependant oligomerization or aggregation
of PBP’s may play a role in allowing insects to distinguish odorant
concentration over such a large range. We are currently investigating
the propensity of PBPLma to oligomerize or aggregate in the presence of
natural and serendipitous ligands to scrutinize the operation of this
signal attenuation mechanism.
Group Members
