Graduate Thesis Or Dissertation

 

Investigating tumor suppression in triploid trout Public Deposited

Analytics
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/nv935723b

Descriptions

Attribute NameValues
Creator
Abstract
  • Previous work (Thorgaard, G. H. et al., Aquatic Toxicology 46:121-126, 1999) showed triploid rainbow trout (0. mykiss) given embryonic carcinogen bath exposures had significant reduction of induced tumors relative to diploids. In the present study, trout were made triploid by thermal shock after fertilization. At age of 5 months they were given dietary carcinogen: aflatoxin B1 (AFB₁) or 7,12-dimethylbenz[a]anthracene (DMBA) for 30 or 120 days. The dietary exposures were at known tumorigenic levels (100, 200 and 300 ppb AFB₁; 250, 500 and 850 ppm DMBA). At about 16 months after fertilization the fish were sacrificed and tumor incidence and multiplicity were assessed. At all levels of carcinogen and in all tumorous organs tumor incidence was lower in the triploid fish. For DMBA-fed fish it was seen that the diploid:triploid incidence ratios ranged from 2.0 to 9.0 and for AFB₁ from 3.1 to 6.0. Weight class analyses dissociated the tumor incidence effects of growth from the effects of triploidy. Weight classes plotted against logit tumor incidence at all doses and durations showed parallel logistic lines. In every case the triploid curve was substantially lower than the diploid curve, showing the independent suppressive effect of triploidy. Fifteen triploid DMBA liver tumors were examined by direct cycle-sequencing of p53 PCR products across the exons 5, 7 and 8 known to contain nearly all human tumor p53 mutations. There were no p53 mutations seen at, or above, the present threshold of detection, (for radiolabeled manual sequencing, under 5% of mutant in normal). Fluorescent sequencing of 15 stomach tumors, also showed no p53 mutations in the hotspot-containing exons. Mutation detection by sequencing the trout Ki-ras1 gene, ortholog human KRAS2, showed codons 12, and 61 mutations in DMBA-fed trout liver and stomach tumors. The DMBA liver tumor Ki-ras1 mutation incidence showed no change by ploidy. There was a significant reduction in Ki-ras1 exon 1 mutations in triploid stomach tumors (5% in triploids v. 33% in diploids, Fisher's Exact test p<O.O5). AFB₁ liver tumors showed Ki-ras1 mutation incidence of 75% (9/12) in diploids and 90% (9/10) triploids, nearly all in exon 1, this mutation difference with respect to ploidy did not reach significance.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Language
Digitization Specifications
  • Master files scanned at 600 ppi (256 Grayscale, 24-bit Color) using Capture Perfect 3.0 on a Canon DR-9080C in TIF format. PDF derivative scanned at 300 ppi (256 B&W, 256 Grayscale, 24-bit Color), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2009-02-20T22:02:26Z (GMT) No. of bitstreams: 1 Ford_Bryan_L_2001.pdf: 2228280 bytes, checksum: cdb930909ccabe306061037972870e6a (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2009-02-20T22:02:07Z (GMT) No. of bitstreams: 1 Ford_Bryan_L_2001.pdf: 2228280 bytes, checksum: cdb930909ccabe306061037972870e6a (MD5)
  • description.provenance : Submitted by Patricia Black (patricia.black@oregonstate.edu) on 2009-02-20T22:01:38Z No. of bitstreams: 1 Ford_Bryan_L_2001.pdf: 2228280 bytes, checksum: cdb930909ccabe306061037972870e6a (MD5)
  • description.provenance : Made available in DSpace on 2009-02-20T22:02:26Z (GMT). No. of bitstreams: 1 Ford_Bryan_L_2001.pdf: 2228280 bytes, checksum: cdb930909ccabe306061037972870e6a (MD5)

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
Ford_Bryan_L_2001.pdf 10/20/2017 Public
Page_82.tif 10/20/2017 Public
Page_113.tif 10/20/2017 Public
Page_116.tif 10/20/2017 Public
Page_151.tif 10/20/2017 Public