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SEASONAL-VARIATION IN THE RELATIVE UTILIZATION OF DIETARY-PROTEIN FOR ENERGY AND BIOSYNTHESIS BY THE MUSSEL MYTILUS-EDULIS
Journal article   Open access

SEASONAL-VARIATION IN THE RELATIVE UTILIZATION OF DIETARY-PROTEIN FOR ENERGY AND BIOSYNTHESIS BY THE MUSSEL MYTILUS-EDULIS

D A Kreeger, AJS Hawkins, B L Bayne and D M Lowe
Marine ecology. Progress series (Halstenbek), v 126(1-3)
01 Oct 1995
url
https://doi.org/10.3354/meps126177View
Published, Version of Record (VoR)Maybe Open Access (Publisher Bronze) Open

Abstract

Ecology Environmental Sciences & Ecology Life Sciences & Biomedicine Marine & Freshwater Biology Oceanography Physical Sciences Science & Technology
Mussels Mytilus edulis were collected from Whitsand Bay in southwest England during April, July and September 1993 and January 1994, and fed a defined diet of prekilled microalgae with one of 2 types of mixed protein/carbohydrate microcapsules. Both capsule types were comprised of the same w/w proportion of N-15-labeled protein and nonlabeled carbohydrate. However, Types 1 and 2 contained trace amounts of [C-14]carbohydrate and [C-14]protein, respectively. Defecation, excretion, respiration and incorporation of C-14 and N-15 isotopes were measured to describe the mussel's relative utilization of dietary carbohydrate (C-14 from Type 1), protein-e (C-14 from Type 2) and protein-N (N-15 from Types 1 and 2). In each experiment, mussels ingested similar quantities of capsule Types 1 and 2. However, the C-14-assimilation efficiency for carbohydrate (16 to 20%) was significantly greater than the C-14-assimilation efficiency for protein (7 to 15%). In contrast, protein-N was always assimilated with greater efficiency (25 to 82%) than either carbohydrate or protein-C. The difference in assimilation efficiency between protein-N and protein-C indicates that a large proportion of amino acids from dietary protein were hydrolyzed, with amino-N being preferentially assimilated. The relatively poor assimilation of amino-C indicates that mussels were not nutritionally Limited by energy since amino-C generated by the energy-intensive digestion process was not fully catabolized in the tricarboxylic acid cycle (i.e. not respired). The conservation of protein-N relative to protein-C was particularly noticeable in July when rates of ingestion and ammonia excretion were lowest, <1% of absorbed [N-15]protein was excreted, and [N-15]protein assimilation was 5 times more efficient than [C-14]protein assimilation. Further, rates of protein synthesis were greatest in July (71.2 mg d(-1)), compared vith April, September and January (39.2, 58.9 and 20.5 mg d(-1)). These findings suggest that seasonal variation in dietary protein utilization in M. edulis is governed chiefly by changing anabolic demands for amino-N, rather than by requirements for energy or essential amino acids.

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Ecology
Marine & Freshwater Biology
Oceanography
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