Skip to main content

Role of oxidative stress and thiol antioxidant enzymes in nickel toxicity and resistance in strains of the green alga Scenedesmus acutus f. alternans

Buy Article:

$50.00 plus tax (Refund Policy)

Abstract:

Treatment with Ni(NO3)2 leads to the formation of reactive oxygen species (ROS) in the green alga Scenedesmus acutus f. alternans, causing lipid peroxidation. This effect was stronger in a Ni-sensitive strain, UTEX72, than in a Ni-resistant strain, B4. In the resistant strain, Ni induced an increased ratio of reduced to oxidized glutathione (GSH:GSSG), whereas it caused a lowered ratio in the sensitive strain. Enzymes involved in the control of ROS were studied in these strains as well as two others that have shown different degrees of nickel resistance. The resistant strain, B4, which grows while containing large amounts of internal Ni, had much higher levels of glutathione reductase and catalase than the other strains. The sensitive strain, UTEX72, had higher levels of glutathione peroxidase, superoxide dismutase, and glucose-6-phosphate dehydrogenase than did strain B4. The resistant strains, Ni-Tol and Cu-Tol, derived from strain UTEX72, which are partly able to exclude Ni, had enzyme profiles that resembled that of UTEX72 more closely than that of B4. Treatment with 10 and 100 µM Ni for 4 or 22 h had complex effects on enzyme levels in all four strains. Ni decreased glutathione reductase in B4, slightly increased it in Ni-Tol and Cu-Tol, and did not affect the low levels of this enzyme in UTEX72. Ni lowered glutathione peroxidase in B4 and either did not affect it or slightly raised it in the other strains. Ni lowered catalase in B4 and did not affect the other strains. Superoxide dismutase was raised in B4 and Ni-Tol and lowered in Cu-Tol and UTEX72, and glucose-6-phosphate dehydrogenase was lowered in all four strains. These results suggest that one major mechanism of Ni resistance, especially in strain B4, may be the ability to combat the formation of ROS when exposed to this metal, likely by maintaining a high GSH:GSSG ratio.Key words: Scenedesmus acutus f. alternans, glutathione reductase, glutathione peroxidase, catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, lipid peroxidation, nickel, reactive oxygen species.

Un traitement avec du Ni(NO3)2 entraîne l'apparition d'espèces qui réagissent avec l'oxygène (ROS) causant une suroxydation des lipides chez l'algue verte Scenedesmus acutus f. alternans. Cet effet était plus prononcé chez la souche UTEX72 sensible au Ni que chez la souche B4 résistante à ce métal. Chez la souche résistante, le Ni causait une augmentation du ratio glutathion réduit en glutathion oxydé (GSH:GSSG), alors que ce ratio diminuait chez la souche sensible. Les enzymes impliquées dans le contrôle de ROS ont été étudiées chez ces souches ainsi que chez deux autres souches présentant des niveaux différents de résistance au Ni. La souche résistante B4, capable de pousser même si elle contient du Ni interne en quantité importante, présentait des niveaux de catalase et de glutathion réductase plus élevés que les autres souches. La souche sensible UTEX72 possédait des quantités plus élevées de glutathion peroxydase, de superoxyde dismutase et de glucose-6-phosphate déshydrogénase que la souche B4. Les souches résistantes Ni-Tol et Cu-Tol, dérivées de la souche UTEX72, en partie capables d'exclure le Ni, présentaient des profils enzymatiques qui ressemblaient plus à ceux de UTEX72 qu'à ceux de la souche B4. Un traitement avec 10 ou 100 µM de Ni pendant 4 ou 22 h avait des effets variables sur les niveaux enzymatiques chez chacune des quatre souches. Le Ni abaissait la glutathion réductase chez B4, l'augmentait légèrement chez Ni-Tol et Cu-Tol et ne modifiait pas les faibles niveaux de cette enzyme chez UTEX72. Le Ni causait une diminution de la glutathion peroxydase chez B4 mais n'avait pas d'influence sur les autres souches. La superoxyde dismutase augmentait chez B4 et Ni-Tol et diminuait chez Cu-Tol et UTEX72. Quant à la glucose-6-phosphate déshydrogénase, elle diminuait chez les quatre souches. Les résultats de cette étude suggèrent qu'un des principaux mécanismes de résistance au Ni, spécialement chez la souche B4, pourrait être la capacité à empêcher la formation de ROS lors d'une exposition à ce métal, probablement en maintenant un ratio GSH:GSSG élevé.Mots clés : Scenedesmus acutus f. alternans, glutathion réductase, glutathion peroxydase, catalase, superoxyde dismutase, glucose-6-phosphate déshydrogénase, suroxydation des lipides, nickel, espèces réagissant à l'oxygèn

Keywords: Scenedesmus acutus f

Document Type: Research Article

Publication date: November 1, 2001

More about this publication?
  • Published since 1954, this monthly journal contains new research in the field of microbiology including applied microbiology and biotechnology; microbial structure and function; fungi and other eucaryotic protists; infection and immunity; microbial ecology; physiology, metabolism and enzymology; and virology, genetics, and molecular biology. It also publishes review articles and notes on an occasional basis, contributed by recognized scientists worldwide.
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Terms & Conditions
  • Sample Issue
  • Reprints & Permissions
  • ingentaconnect is not responsible for the content or availability of external websites
nrc/cjm/2001/00000047/00000011/art00003
dcterms_title,dcterms_description,pub_keyword
6
5
20
40
5

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more