Understanding lamprey reproduction by examining olfactory sensory neurons.

The sea lamprey is an invasive jawless fish species in the Great Lakes. Its voracious appetite for salmon and whitefish led to the collapse of fisheries in Lake Erie during the past century. Currently, sea lamprey populations are controlled by vigilant management strategies. One target is the disruption of lamprey spawning migration and reproduction. Both are guided by pheromones, odorants released by other lampreys. Lampreys have distinct behavioural responses to specific pheromones. The polyamine, spermine, stimulates reproductive behaviour, but spermidine (which has fewer hydrocarbons and amine groups less than spermine) does not stimulate a behavioural response. My study investigates if olfactory sensory neurons are narrowly tuned to spermine and spermidine or if these cells are broadly tuned (as we see in rodents and humans). Calcium imaging was used to observe the cellular responses to odorants. I observed that spermine and spermidine elicit a one-cell one-odorant response profile in sea lamprey olfactory sensory neurons. The concentration threshold for the cellular responses to spermine was lower than for spermidine. This study supports the idea of odorant fidelity to specific olfactory sensory neurons in the sea lamprey. The odorant activation of single olfactory sensory neurons by an odorant may contribute to the specific responses to specific lamprey pheromones. This knowledge of cellular activity behind sea lamprey biology contributes to ongoing research utilizing pheromone communication to disrupt sea lamprey reproduction