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Hydrobiologia

, Volume 38, Issue 2, pp 165–184 | Cite as

Ecophysiologie de quelques Desmidiées: II. Perturbations expérimentales de la nitrate — respiration

  • C. van der Ben
Article

Résumé

L'étude porte sur deux Desmidiées dont l'activité nitrate-respiratoire a déjà fait l'objet d'un travail précédent.

On observe que les algues carencées en azote perdent leur activité nitrate-réductrice, tandis qu'elles utilisent des quantités de nitrite beaucoup plus grandes que dans les conditions expérimentales habituelles.

En présence d'acide ascorbique, on note une modification fréquente, mais variable, des activités nitrate- et nitrite-réductrices. Les algues protègent cet acide et les nitrites contre une oxydo-réduction réciproque.

Les algues étudiées semblent pouvoir utiliser, suivant les circonstances, différents systèmes énergétiques.

Summary

Previous experiments (C. van der Ben, 1970) have shown that several species of Desmids are able to reduce nitrates to nitrites in vivo. This reducing property depends greatly on various environmental factors such as pH, temperature, light and nitrate concentration.

The present paper analyses some conditions of this nitrate-reducing capacity, i.e. nitrate-respiration. The factors investigated are nitrogen-privation and action of ascorbic acid. It has been found that Staurastrum cultures deprived of nitrogen after exponential growth phase become unable to reduce nitrates but their nitrite-reduction is enhanced. The present observations show that algal suspensions protect ascorbic acid and nitrites against mutual destruction.

In the presence of ascorbic acid, the nitrate- and nitrite-reducing activity of the algae is frequently and variably modified. Staurastrum and Cosmarium seem to have the ability to switch to various energetic sources according to environmental conditions.

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Bibliographie

  1. Ben, C. van der - 1970 - Ecophysiologie de quelques Desmidiées. I. Un mode d'utilisation des nitrates. Hydrobiologia, 36, 3–4: 419–442.Google Scholar
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Copyright information

© Dr. W. Junk n.v. Publishers 1971

Authors and Affiliations

  • C. van der Ben
    • 1
  1. 1.Laboratoire de Physiologie VégétaleFaculté des Sciences de RennesFrance

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