Journal article
Unilateral ovariectomy increases egg size and reduces follicular atresia in the semelparous coho salmon, Oncorhynchus kisutch
Journal of experimental zoology. Part A, Ecological genetics and physiology, Vol.309A(8), pp.468-476
10/2008
Handle:
https://hdl.handle.net/2376/108593
PMID: 18618597
Abstract
Unilateral ovariectomy (ULO, removal of one ovary) is a powerful technique for studying aspects of reproductive physiology, including follicular recruitment and growth. To examine effects of ULO for the first time in a semelparous species, coho salmon (Oncorhynchus kisutch) were unilaterally ovariectomized during mid‐vitellogenesis approximately 3 months before spawning. At termination of the study (79 days post‐surgery), single ovaries of ULO fish were gravimetrically equivalent to paired ovaries of sham surgery, control fish. There was no evidence of recruitment of new vitellogenic follicles. Instead, the dramatic increase in ovary mass was attributable to hypertrophy of existing vitellogenic follicles (33% increase in volume) and increased fecundity achieved through a greater than two‐fold reduction in follicular atresia. The composition of whole ovaries on a dry weight basis from ULO fish was greater in protein, but lower in lipid than that of control fish. Expressing the data on a per follicle basis, however, showed that follicles of ULO fish contained more protein, ash, water, and lipid. The results indicate that ULO of coho salmon induces compensatory hypertrophy of existing vitellogenic follicles, while maximizing fecundity through reduction of atresia. Thus, 3 months before spawning, coho salmon exhibit the ability to adjust final egg size and number when faced with significant depletion of ovarian follicles. This in vivo system provides a platform for further study of physiological mechanisms regulating follicular growth and atresia, and the trade‐off between egg size and egg number. J. Exp. Zool. 309A:468–476, 2008. © 2008 Wiley‐Liss, Inc.
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Details
- Title
- Unilateral ovariectomy increases egg size and reduces follicular atresia in the semelparous coho salmon, Oncorhynchus kisutch
- Creators
- John Adam LuckenbachMakoto KusakabePenny SwansonGraham Young
- Publication Details
- Journal of experimental zoology. Part A, Ecological genetics and physiology, Vol.309A(8), pp.468-476
- Academic Unit
- UNKNOWN
- Publisher
- Wiley Subscription Services, Inc., A Wiley Company; Hoboken
- Number of pages
- 9
- Grant note
- National Research Initiative Competitive Grants USDA Cooperative State Research, Education, and Extension Service (2007‐35203‐18082; 2003‐35203‐13602) Japan Society for the Promotion of Science Fellowship Bonneville Power Administration Project (93‐056)
- Identifiers
- 99900547246901842
- Language
- English
- Resource Type
- Journal article