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Prolactin and freshwater osmoregulation of juvenile chum Oncorhynchus keta and sockeye O. nerka salmon Neuman, H. R.

Abstract

The possible role of prolactin in the freshwater osmoregulation of laboratory reared juvenile chum (Oncorhynchus keta) and sockeye (0. nerka) salmon was investigated. Pituitary cytology indicated that prolactin cells of both species develop gradually during freshwater residence and downstream migration. During this time the prolactin cells increase slightly in size; the number of prolactin cell follicles also increases. Simultaneously, the intensity of cytoplasmic staining with erythrosin increases. Alternate day injections of 5 or 15 μg/g body wt prolactin (ovine) did not affect survival of chum fry in deionized water. Thirty micrograms per gram slightly increased survival while 60 μg/g decreased survival in deionized water. Prolactin injections prolonged, to a small extent, the survival of sockeye smolts in deionized water. Sockeye fry suffered only slight mortality after transfer from fresh water to deionized water. A prolactin dose of 5 μg/g did not alter this survival; however, doses of 15 μg/g or higher resulted in 40 to 70% mortality after 10 days in deionized water. Alternate day injections of 10 μg/g prolactin had no effect on plasma sodium concentrations of chum fry, sockeye fry, or sockeye smolts after transfer from sea water to either fresh water or deionized water. It is concluded, from histological and physiological evidence, that prolactin does not play an obvious role in the freshwater osmoregulation of juvenile chum and sockeye salmon. The possible role of prolactin in the spawning migration of adults is discussed.

Item Metadata

Title
Prolactin and freshwater osmoregulation of juvenile chum Oncorhynchus keta and sockeye O. nerka salmon
Creator
Neuman, H. R.
Publisher
University of British Columbia
Date Issued
1974
Description
The possible role of prolactin in the freshwater osmoregulation of laboratory reared juvenile chum (Oncorhynchus keta) and sockeye (0. nerka) salmon was investigated. Pituitary cytology indicated that prolactin cells of both species develop gradually during freshwater residence and downstream migration. During this time the prolactin cells increase slightly in size; the number of prolactin cell follicles also increases. Simultaneously, the intensity of cytoplasmic staining with erythrosin increases. Alternate day injections of 5 or 15 μg/g body wt prolactin (ovine) did not affect survival of chum fry in deionized water. Thirty micrograms per gram slightly increased survival while 60 μg/g decreased survival in deionized water. Prolactin injections prolonged, to a small extent, the survival of sockeye smolts in deionized water. Sockeye fry suffered only slight mortality after transfer from fresh water to deionized water. A prolactin dose of 5 μg/g did not alter this survival; however, doses of 15 μg/g or higher resulted in 40 to 70% mortality after 10 days in deionized water. Alternate day injections of 10 μg/g prolactin had no effect on plasma sodium concentrations of chum fry, sockeye fry, or sockeye smolts after transfer from sea water to either fresh water or deionized water. It is concluded, from histological and physiological evidence, that prolactin does not play an obvious role in the freshwater osmoregulation of juvenile chum and sockeye salmon. The possible role of prolactin in the spawning migration of adults is discussed.
Genre
Thesis/Dissertation
Type
Text
Language
eng
Date Available
2010-01-22
Provider
Vancouver : University of British Columbia Library
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.
DOI
10.14288/1.0093134
URI
http://hdl.handle.net/2429/18924
Degree
Master of Science - MSc
Program
Zoology
Affiliation
Science, Faculty of; Zoology, Department of
Degree Grantor
University of British Columbia
Campus
UBCV
Scholarly Level
Graduate
Aggregated Source Repository
DSpace

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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.