Date of Award

8-3-2017

Degree Type

Thesis

Degree Name

M.Sc.

Department

Biological Sciences

First Advisor

Zielinski, Barbara

Keywords

amino acids, Chinook salmon, glomerular patterning, neural development, olfactory sensory neurons, phenyl ethyl alcohol

Abstract

In teleosts, Golf positive ciliated, calretinin positive microvillous and S100 positive crypt morphotypes of olfactory sensory neurons (OSNs) respond to different odorants (bile acids, amino acids and sex steroids respectively) and project axons to glomeruli in specific stereotyped areas of the olfactory bulb. In this thesis, the diversity of OSNs and their olfactory bulb glomeruli was described using calretinin, Golf and S100 immunocytochemistry in Chinook salmon embryos, larvae and fingerlings. Olfactory learning, such as imprinting to natal waters, occurs during these early stages. Calretinin immunoreactivity was present in lateral glomeruli lG1, lG3/4, lG6 and dorsal lateral glomerular chain (dlG) from embryonic stages. At late larval and fingerling stages calretinin also labeled some medial anterior glomeruli (maG), ventromedial glomeruli (vmG) and a ventroposterior glomerulus (vpG1). Golf immunoreactivity was seen in medial and ventral olfactory bulb regions, specifically in ventral medial glomeruli vmGx, vmG7 and the dlG in embryos and additional dorsal glomeruli (dG), maG, smaller vmGs and vpG2 starting from late yolk-sac larval stage. S100 immunoreactivity was present in lateral regions of the olfactory bulb at the fingerling stage. Amino acid (40-450 nM), a potential imprinting odour, or phenylethyl alcohol (10-7M), an odour used in salmon imprinting studies and not found endogenously in municipal water, exposure over larval development resulted in decreased glomerular volumes of lG3/4 or vmG7 at early yolk-sac larvae and late yolk-sac larvae stages, respectively. No difference was observed at other larval periods or for other lGs and vmGs. Different timing of development of various glomeruli may be important for understanding their role in salmon behaviour and the learning of olfactory cues.

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