Biol. Bull.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by McAuley, P. J.
Right arrow Search for Related Content
PubMed
Right arrow Articles by McAuley, P. J.

The Biological Bulletin, Vol 188, Issue 2 210-218, Copyright © 1995 by Marine Biological Laboratory

PHYSIOLOGY

Ammonium Metabolism in the Green Hydra Symbiosis

P. J. McAuley
School of Biological and Medical Sciences, Sir Harold Mitchell Building, University of St. Andrews, St. Andrews, Fife, KY16 9TH, United Kingdom

Inhibitors of enzymes of ammonium assimilation were used to test if assimilation of ammonium in the green hydra-Chlorella symbiosis was due to host or symbionts. Both methionine sulphoximine (MSX, an inhibitor of glutamine synthetase, found in both host and symbionts) and azaserine (AZS, an inhibitor of 2-oxoglutarate amido transferase, not found in the host) inhibited ammonium uptake by the intact symbiosis. MSX was taken up and caused predictable changes in pools of glutamate and glutamine in both freshly isolated symbionts and cultured ex-symbiotic Chlorella. However, after treatment of the intact symbiosis with MSX, no MSX was found in the symbiotic Chlorella, and glutamine and glutamate pools of both host and symbionts were unaffected. Although both MSX and AZS inhibited ammonium uptake by Chlorella, MSX caused seven times as much ammonium release from the intact symbiosis as did AZS. AZS treatment of the intact symbiosis caused an increase in glutamine pools in both host and symbionts, and AZS also competitively inhibited glutamine uptake by Chlorella. Further, ammonium treatment of intact hydra did not affect the nitrogen status of the algal symbionts, although it did cause a small increase in the number of algae in each digestive cell of the host. It is suggested that primary ammonium assimilation in the green hydra symbiosis occurs by means of animal glutamine synthetase, and that the resulting glutamine may be taken up and further processed by the symbiotic algae. Freshly isolated symbionts were able to process glutamine into glutamate even when incubated at low pH, which causes them to release a substantial proportion of fixed carbon as maltose.


This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
R. Lee, J. Robinson, and C. Cavanaugh
Pathways of inorganic nitrogen assimilation in chemoautotrophic bacteria-marine invertebrate symbioses: expression of host and symbiont glutamine synthetase
J. Exp. Biol., January 2, 1999; 202(3): 289 - 300.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1995 by the Marine Biological Laboratory.