Sensing the environment: using olfaction to understand dietary preferences in lake sturgeon Acipenser fulvescens

Olfaction contributes significantly to the ability of the Lake sturgeon Acipenser fulvescens to sense its environment and is a crucial mechanism for feeding. The olfactory epithelium consists of multi-lamellar mucosal folds, which are in constant contact with the external environment. The olfactory epithelium contains three olfactory sensory neurons (OSNs)¬—ciliated, microvillous, and crypt cells—that detect unique compounds such as amino acids, bile salts, and pheromones, respectively. I used electro-physiological and behavioural techniques to evaluate diet cue detection and potential transduction pathways of olfaction in one-year-old Lake sturgeon to current hatchery and wild-type diet cues in two separate experiments. The amplitude of electro-olfactogram (EOG) response did not correlate to increased foraging activity in the behavioural arena, although a significant behavioural response to hatchery diet was observed. Additionally, I observed detection of complex dietary cues required both ciliated and microvillous OSNs. To investigate if treatment with a simple amino acid L-alanine during early life stage influenced olfactory development and survival, I reared larval Lake sturgeon and acutely exposed them to L-alanine. I used molecular, electro-physiological and behavioural techniques to assess the effects of L-alanine. Acute treatment with L-alanine elicited significant differences in mRNA transcript abundance of key olfactory genes V2R 1-like, V2R 26-like, OR 1-like and TAAR 1-like as well as differences in foraging behaviour in age-0 Lake sturgeon. These finding suggests that olfactory cues in the environment could play a role in early larval and juvenile development creating low performance phenotypes in hatchery programs as release of these fish raised in non-native waters fed consistent diets could result in a mismatch between these fish and the environment they are transferred to.