Intrashell variations in amino acid concentrations and isoleucine epimerization ratios in fossil Hiatella arctica

Research Article| September 01, 1983 Intrashell variations in amino acid concentrations and isoleucine epimerization ratios in fossil Hiatella arctica Julie K. Brigham Julie K. Brigham 1Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309 Search for other works by this author on: GSW Google Scholar Author and Article Information Julie K. Brigham 1Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1983) 11 (9): 509–513. https://doi.org/10.1130/0091-7613(1983)11<509:IVIAAC>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Julie K. Brigham; Intrashell variations in amino acid concentrations and isoleucine epimerization ratios in fossil Hiatella arctica. Geology 1983;; 11 (9): 509–513. doi: https://doi.org/10.1130/0091-7613(1983)11<509:IVIAAC>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Twenty-four valves of fossil Hiatella arctica were analyzed to determine if amino acid ratios varied from one region of a shell to another. The ratio of D-alloisoleucine/L-isoleucine, routinely used as a stratigraphic correlation tool and an indicator of relative age, did not vary significantly between five anatomically different shell parts in Hiatella arctica. Sampling only the hinge or central part of all valves, however, resulted in less variation about the average value. Analyses of only this part of the shell should improve the resolution of stratigraphic units by amino acid geochronology. The absolute concentrations of aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, alloisoleucine, isoleucine, and leucine (in picomoles/milligram of shell) are significantly higher in the hinge and central part of the shell, whereas the outer growth edge appears to have lower levels of amino acids. This is true in both the FREE and TOTAL hydrolysate fractions. The reasons are not clear; however, the high value may be caused by a thin, protein-rich inner layer lining the valve out to the pallial line and/or differences in the proportion of inorganic carbonate to protein produced in different areas during shell growth. Alternatively, it may suggest leaching of the thinner, more vulnerable part of the shell growth edge. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.