Sex steroid profiles of coho salmon, Oncorhynchus Kisutch, during early development and sexual differentiation Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/vm40xv39j

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Whole body sex steroid levels of coho salmon, Oncorhynchus kisutch, were measured via radioimmunoassay during early development and sexual differentiation. Steroid profiles of testosterone (T), 11-ketotestosterone (KT) , androstenedione (A), progesterone (P4) , 17β, -hydroxy- 20β -dihydroprogesterone (DHP) , and 17β -estradiol (E2) were generated beginning with unfertilized eggs and ending at 87 days post-fertilization (DPF). Ovarian fluid was also examined for steroid content. At hatching (42 DPF) an androstenedione assay was substituted for the P4 assay. Onset of exogenous feeding occurred at 60 DPF. Steroid profiles of unfertilized eggs essentially paralleled that found for ovarian fluid. Following fertilization, steroid levels in developing embryos declined precipitously until 30 DPF. At hatch, levels of all steroids increased slightly and then declined during yolk sac absorption. Levels of the androgens (T, KT, and A) followed similar patterns during this time while DHP and E2 content also showed similar trends to one another. During yolk sac absorption yolk and embryos were separated from each other and assayed individually. Steroid content of yolk declined while it generally increased or remained constant in the embryos. Varying degrees of bimodality appeared in the data regarding steroid levels within samples of fish collected between 42 and 56 DPF. The bimodal distributions of steroids disappeared at the onset of feeding and did not return again until 87 DPF. The hormone levels generally decreased or remained constant following the onset of exogenous feeding, except for E2, whose levels increased during this time. Histological analyses showed the presence of undifferentiated gonads between hatching and 70 DPF. By 77 DPF ovarian development could be easily discerned. Fish born the following brood year were presumptively sexed at 101 DPF and steroid levels were determined; a sexual dimorphism was apparent in levels of T, KT, and A, but not for DHP or E2. The increase in steroid content of developing coho at hatch, coupled with their bimodal distributions during yolk sac absorption and the increase in E2 levels during ovarian development may suggest a possible role of sex steroids in the process of sexual differentiation apparent later in development. Changes in whole body steroid levels at hatch may also be indicative of the onset of sexual differentiation even though no signs of gonadal differentiation were histologically discernable at that time.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome, 8-bit Grayscale) using ScandAll PRO 1.8.1 on a Fi-6670 in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Submitted by Katy Davis (kdscannerosu@gmail.com) on 2013-05-20T22:49:10Z No. of bitstreams: 1 FeistGrant1989.pdf: 839273 bytes, checksum: 3eb457ab81bd7b53315233892b5af976 (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-05-24T17:20:00Z (GMT) No. of bitstreams: 1 FeistGrant1989.pdf: 839273 bytes, checksum: 3eb457ab81bd7b53315233892b5af976 (MD5)
  • description.provenance : Made available in DSpace on 2013-06-12T18:00:09Z (GMT). No. of bitstreams: 1 FeistGrant1989.pdf: 839273 bytes, checksum: 3eb457ab81bd7b53315233892b5af976 (MD5) Previous issue date: 1988-05-25
  • description.provenance : Approved for entry into archive by Deborah Campbell(deborah.campbell@oregonstate.edu) on 2013-06-12T18:00:09Z (GMT) No. of bitstreams: 1 FeistGrant1989.pdf: 839273 bytes, checksum: 3eb457ab81bd7b53315233892b5af976 (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items