Dissertation/Thesis Abstract

Determining the Relationship of Protein Metabolism and Phenotypic Plasticity in Larvae of the Sand Dollar, Dendraster excentricus
by Ellison, Aimee, M.S., California State University, Long Beach, 2020, 63; 27671303
Abstract (Summary)

The ability of planktotrophic larvae to find sufficient food in the nutritionally heterogeneous marine environment has marked consequences for subsequent growth, survival and recruitment. The morphological plasticity seen in larvae of the sand dollar, Dendraster excentricus, as a response to varying food conditions represents one of the strategies used by organisms to match their growth and development to the environment. Previous research modeling energetic growth efficiencies found that D. excentricus larvae also exhibit physiological plasticity in response to different food concentrations. This previous study showed clear energetic advantages for low-fed larvae in early development that decreased rapidly and were substantially less than high-fed larvae in later development, especially in relation to protein growth efficiency (PGE) (defined as protein growth/protein ingested). Given the importance of protein metabolism in setting metabolic rates and growth-related efficiencies, my research seeks to further understand the biochemical reason for the large differences in PGE between low- and high-fed larvae (1,000 and 10,000 algal cells ml-1, respectively). In order to determine the differential rates and costs of protein synthesis in differing physiological feeding states, parallel measurements of protein synthesis, metabolic rates, and protein biomass growth were determined throughout larval development. High-fed larvae were found to have higher rates of protein synthesis compared to low-fed larvae while fractional rates of protein synthesis were not significantly different between treatments. Protein-specific rates of amino acid transport were almost 2-times higher in low-fed larvae than in high-fed. No differences were observed in either the energetic cost of protein synthesis (3.8 J (mg protein)-1) or the proportion of aerobic energy that was used to drive protein synthesis (37-42% of metabolism). Major differences, which mirrored changes in PGE with development, were observed in protein depositional efficiency (PDE). Low-fed larvae exhibited a decrease in PDE from 85% to 40% from 4 to 28 days post-fertilization while high-fed larvae increased from 55% to 65%. These differences in PDE provide a physiological explanation for the large differences in PGE between low- and high-fed larvae. Findings from this study support the idea that protein metabolism as a critical element in the developmental plasticity of larvae to differing food environments and aids in understanding, on a biochemical level, how metabolic growth efficiencies change in response to environmental factors.

Indexing (document details)
Advisor: Pace, Douglas
Commitee: Pernet, Bruno, Allen, Bengt
School: California State University, Long Beach
Department: Biological Sciences
School Location: United States -- California
Source: MAI 81/9(E), Masters Abstracts International
Subjects: Biology, Physiology, Developmental biology
Keywords: Dendraster excentricus, Growth efficiency, Larvae, Phenotypic plasticity, Physiology, Protein metabolism
Publication Number: 27671303
ISBN: 9781658443395
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