Effedts of confinement Volume on Ureogenesis in the Gulf Toadfish Opsanus Beta
Loading...
Authors
Beebe, Rebecca
Issue Date
1994
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
The gulf toadfish, Opsanus beta, is a facultative ureotele that, when
stressed, can excrete nitrogenous waste as urea instead of ammonia. This
study focused on the relationship between cortisol, hepatic glutamine
synthetase (GNS) activity, and the form of nitrogen excreted (urea or
ammonia) in toadfish that were confined to variable water volumes and
fish that were unconfined. Fish were placed individually in tubs
containing 2, 4, 6 or 8 I of sea water for 48 h during which time the
ureogemc indicators (nitrogen excretion rates, cortisol and GNS levels)
were measured. Throughout the first 24 h, fish excreted predominantly
ammomia with low total nitrogen excretion rates. A transition to urea
excretion was seen at the end of the 48 h, with an overall higher rate of
total nitrogen excretion. In addition, plasma cortisol levels were elevated,
while GNS levels showed only a slight but non-significant Increase.
Findings from this study show that confinement elicits ureogenesis.
However, results indicate that differences in water volume within the
range tested did not affect the degree of ureogenesis expressed by fish.
Results of this study support the hypothesis that when toadfish are
stressed they begin producing urea. Additionally, it demonstrates that the
threshold confinement volume eliciting the stress response is greater than
8 I. However, the ecological relevance of this phenomenon remains to be
definitively identified.
Description
v, 22 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.