• Login
    View Item 
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UMB Digital ArchiveCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    Display statistics

    Chemical-induced alterations in heme/porphyrin metabolism as bioindicators of sublethal stress in fish

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Find Full text
    Author
    Conner, Elizabeth Ann
    Advisor
    Fowler, Bruce A.
    Date
    1992
    Type
    dissertation
    
    Metadata
    Show full item record
    Abstract
    Selective inhibition of {dollar}\delta{dollar}-aminolevulinic acid dehydratase (ALAD) in mammals by lead (Pb) has served as an important biological marker of chemical exposure and injury. Water-borne exposure of fish to Pb was shown to inhibit ALAD in the blood, liver and kidney of several fish species. The relative susceptibility of ALAD to Pb inhibition in channel catfish (Ictalurus punctatus) and the biochemical characteristics of the fish hepatic enzyme were evaluated. Intraperitoneal injections of 0.5, 1.0 and 10.0 mg Pb/kg resulted in reduction of blood and liver ALAD activity but no change in hematocrit or zinc-protoporphyrin, which suggested that the fish heme biosynthetic pathway is less sensitive to Pb than mammals. Kinetic analyses of fish hepatic ALAD activities indicated a Km of 4 {dollar}\times{dollar} 10{dollar}\sp{lcub}-5{rcub}{dollar} M ALA and a Vmax of 2.57 {dollar}\pm{dollar}.218 nmol porphobilinogen (PBG)/hr/mg. The IC{dollar}\sb{lcub}50{rcub}{dollar} for Pb inhibition of fish liver ALAD activity was 40 times higher than those values found for mammals. Other in vitro studies demonstrated that, in contrast to mammals, fish hepatic ALAD was not activated by zinc and only moderately inhibited by EDTA. Western blot studies using rabbit polyclonal antibodies directed to mammalian ALADs suggested weak immunological cross-reactivity. In addition, a 10 KDa lead-binding protein (PbBP) in the liver of the channel catfish was isolated and partially characterized. These results provide further comparative biochemical data that tissue-mediating factors may play a role in the intracellular availability of Pb to sensitive biochemical processes in fish. Thus, the relative resistance of fish hepatic ALAD activity to Pb inhibition in comparison to mammals appears to be the result of two mediating factors (i) intrinsic differences in the fish hepatic enzyme; and (ii) the presence of a PbBP.
    Description
    University of Maryland, Baltimore. Toxicology. Ph.D. 1992
    Keyword
    Health Sciences, Toxicology
    Environmental Sciences
    Identifier to cite or link to this item
    http://hdl.handle.net/10713/2518
    Collections
    Theses and Dissertations All Schools
    Theses and Dissertations School of Medicine

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Policies | Contact Us | UMB Health Sciences & Human Services Library
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.