Mercury and cadmium binding proteins in marine mammal tissues Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0c483n77b

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The subcellular fractions of liver and kidney from three bearded seals (Erignathus barbatus nauticus) and three walrus (Odobenus rosmarus divergens) were analyzed for cadmium and mercury content, and the results were compared with the results of subcellular fractionation of the same organs from two sea lions (Zalophus callfornianus californianus) obtained previously in our laboratory (Lee et al. , 1976). When the heavy metal concentration in the cytosol was plotted against that in the whole cell, evidence for two phases of accumulation of heavy metals in the cytosol was obtained. At low cellular concentrations, proportionally more heavy metal was found in the cytosol than at higher concentrations. Under these latter conditions, cadmium had accumulated in the cytosol to a lesser degree, while mercury concentration remained constant. The soluble fractions of kidney and liver from two bearded seals and three walrus were chromatographed on Sephadex G-75 and cadmium and mercury distribution among proteins of different molecular weight was determined. Similar results for two sea lions (Lee et al. , 1976) were compared with the ones for the arctic marine mammals. At low concentrations of heavy metals in the cytosol, the amount of metals in metallothionein was related much closer to that in the cytosol than at higher concentrations, where a very limited degree of linear correlation was observed. Two types of heavy metal binding sites with different affinities are a likely explanation for these biphasic distribution curves. Mercury thus showed a distinct tendency to accumulate in the particulate fractions and the soluble proteins of high molecular weight, whereas cadmium was found much more in the soluble and metallothionein fractions. Liver was recognized as the main organ to deposit mercury and kidney as a major site for cadmium accumulation in all three species. Nevertheless, the same general principle(s) appeared to govern heavy metal distribution in both organs. A search in sea lion liver for a soluble protein of high molecular weight that binds mercury specifically failed to demonstrate such a protein, but showed that mercury binds nonspecifically to a great number of soluble proteins of around 150, 000 daltons. Use of a specific assay to measure metallothionein levels in livers and kidneys of three bearded seals, three walrus, and three sea lions revealed a very low degree of linear correlation between metallothionein content and heavy metal concentration. Only cadmium levels in the kidney cytosol were correlated to some extent (R²=0. 56) with the amounts of metallothionein found in the same organs. These results are inconsistent with the induction of metallothionein by high heavy metal concentrations in marine mammals. The 10, 000 x g supernatant of sea lion liver homogenate containing an active mixed function oxidase system was found to catalyze the demethylation of added methylmercury in vitro at a rate of 22% in 16. 5 h.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. 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 2013-12-04T15:49:39Z (GMT) No. of bitstreams: 1 vonderTrenckKarl1976.pdf: 1492797 bytes, checksum: cd545724695c43a7c632c46989a96a1d (MD5)
  • description.provenance : Made available in DSpace on 2014-01-02T19:40:33Z (GMT). No. of bitstreams: 1 vonderTrenckKarl1976.pdf: 1492797 bytes, checksum: cd545724695c43a7c632c46989a96a1d (MD5) Previous issue date: 1975-11-17
  • description.provenance : Submitted by Georgeann Booth (gbscannerosu@gmail.com) on 2013-12-04T00:52:16Z No. of bitstreams: 1 vonderTrenckKarl1976.pdf: 1492797 bytes, checksum: cd545724695c43a7c632c46989a96a1d (MD5)
  • description.provenance : Approved for entry into archive by Kirsten Clark(kcscannerosu@gmail.com) on 2014-01-02T19:40:33Z (GMT) No. of bitstreams: 1 vonderTrenckKarl1976.pdf: 1492797 bytes, checksum: cd545724695c43a7c632c46989a96a1d (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items