QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online February 29, 2008
Journal of Experimental Biology 211, 860-865 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.012807

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Grover, R. Articles by Ferrier-Pagès, C. PubMed PubMed Citation Articles by Grover, R. Articles by Ferrier-Pagès, C.

Uptake of dissolved free amino acids by the scleractinian coral Stylophora pistillata

Renaud Grover^1,*, Jean-François Maguer², Denis Allemand¹ and Christine Ferrier-Pagès¹

¹ Centre Scientifique de Monaco, Avenue Saint Martin, MC-98000, Monaco
² Laboratoire de Chimie Marine, Institut Universitaire Européen de la Mer, Place Nicolas Copernic, F-29280 Plouzane, France

^* Author for correspondence (e-mail: rgrover{at}centrescientifique.mc)

Accepted 19 January 2008

This study was designed to assess the importance of dissolved free amino acids (DFAA) as a nitrogen source for the scleractinian coral Stylophora pistillata. For this purpose, experiments were performed using ¹⁵N-enriched DFAAs, and %¹⁵N enrichment was measured both in animal tissue and zooxanthellae at different DFAA concentrations, incubation time and light levels. As previously observed for urea, which is another source of organic nitrogen, DFAA uptake exhibited a biphasic mode consisting of an active carrier-mediated transport for concentrations below 3 µmol l^–1 and a linear uptake for higher concentrations. The value of the carrier affinity (K_m=1.23 µmol l^–1 DFAA) indicated good adaptation of the corals to the low levels of DFAA concentrations measured in most oligotrophic waters. DFAA uptake was also correlated with light. The DFAA contribution to the nitrogen requirements for tissue growth was compared to the contribution of ammonia, nitrate and urea, for which uptake was also measured in S. pistillata. Inorganic sources (NH₄⁺ and NO₃^–) contributed 75% of the daily nitrogen needs against 24% for organic sources. Taken altogether, dissolved organic and inorganic nitrogen can supply almost 100% of the nitrogen needs for tissue growth.

Key words: coral, isotopic enrichment, uptake, kinetics, dissolved free amino acid