Numerous studies have determined approximate locations of chemoreceptive cells in
freshwater fish, with the majority suggesting the gills as the primary oxygen-sensing site.
Using immunohistochemistry, I investigated the distribution of neurotransmitters and
markers for neuroepithelial cells (NECs), the putative oxygen sensing cells, in gills of
freshwater fish with varying degrees of hypoxia tolerance. I compared the patterns of
immunoreactivity of NEC markers (anti-serotonin and anti-synaptic vesicle marker) in two
distantly related species with different hypoxia tolerances (Onchoryncus mykiss and
Carassuis auratus) as well as two species from the same genus (Hoplias) that possess distinct
differences in habitat and hypoxia tolerance. To speculate on the role of other potential
chemosensory neurotransmitters in the gill, I also examined the distribution of
catecholamines, acetylcholine, and adenosine. I found that all fish exhibited a cluster of
innervated, serotonergic NECs at the filament tip acting as putative chemoreceptors,
consistent with the ability of all fish to respond to aquatic hypoxia, while unique distributions
of serotonergic NECs associated with the efferent filament artery correlated with
physiological responses to internal hypoxia. These differences in serotonergic NEC
distribution appeared to be adaptations related to hypoxia tolerance. Catecholaminergic cells
were distinctly different from serotonergic cells, but often colocalized with acetylcholine.
Cells containing both acetylcholine and catecholamine were located neighboring serotonergic
cells. I propose that the non-innervated serotonergic cells of the lamellae, which are unique to
hypoxia tolerant fish, play a chemosensory role in oxygen-sensing and function as
neuromodulators acting directly on local vasculature or neighboring acetylcholinecatecholamine-
containing cells. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/32237 |
| Date | January 2006 |
| Creators | Coolidge, Emily Hayes |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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