Abstract:
Odorant receptors constitute the largest gene family in rodents and probably in all vertebrates. In addition to detecting the odorant molecules in the outside world, odorant receptorrs are responsible for some critical aspects of olfactory sensory neuron development including odorant receptor gene choice and axonal guidance. Although it is widely accepted that any given olfactory sensory neuron expresses only one odorant receptor out of a repertoire of almost a 1000 genes, it is still unknown how the singularity in odorant receptor gene expression is established. On the other hand, it has been suggested that a negative feedback signal is emitted from the OR proteins to suppress the expression of other ORs. Zebrafish, with only ~140 odorant receptors and very similar organization of olfactory system compared to mammals, is an ideal model organism to investigate the unknown features of odorant receptor gene choice. In the first part of this thesis, temporal dynamics of regulation of odorant receptor gene choice was analyzed by using a conditional zebrafish OR111-7 ablation transgene. In the second part, the importance of OR111-7 coding sequence in the negative feedback signal dependent inhibition of OR111- 7 reporter transgene expression was investigated.
