Journal of Environmental Biology

Age effect on the antioxidant activity of Daphnia magna

(Anomopoda: Daphniidae): Does younger mean more sensitivity?

Author Details

Arzate-C?rdenas Mario Alberto

Laboratorio de Hidrobiolog?a Experimental, Departamento de Zoolog?a, Escuela Nacional de

Ciencias Biol?gicas-IPN, Plan de Ayala y Prolongaci?n de Carpio, M?xico D.F., C.P. 11340. M?xico

Ortiz-Butr?n Roc?o

Laboratorio de Fisiolog?a Humana, Departamento de Fisiolog?a, Escuela Nacional de

Ciencias Biol?gicas-IPN, Plan de Ayala y Prolongaci?n de Carpio, M?xico D.F., C.P. 11340. M?xico.

Mart?nez-Jer?nimo Fernando

(Corresponding author)

Laboratorio de Hidrobiolog?a Experimental, Departamento de Zoolog?a, Escuela Nacional de Ciencias

Biol?gicas-IPN, Plan de Ayala y Prolongaci?n de Carpio, M?xico D.F., C.P. 11340. M?xico

e-mail: fjeroni@ipn.mx

Publication Data

Paper received:

2 March 2010

Revised received:

28 July 2010

Accepted:

23 September 2010

Abstract

It has been accepted that for most species newborns and senescent organisms are more sensitive than other ages to environmental stressors. Nevertheless, it must be considered that there are several biochemical and physiological compensatory processes which are not expressed with the same magnitude during the whole life cycle. With this aim, Daphnia magna individuals of different age were exposed to hexavalent chromium, Cr (VI), at two different sublethal concentrations (0.032 and 0.0064 mg l^-1), and the activity of some antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) were evaluated during most of the life cycle of this cladoceran. The antioxidant enzymatic activity showed an inverse relationship with respect to age. The activity of CAT, GR and GPx were increased in the two treated groups, at all life stages tested. On the other hand, the activity of SOD decreased in the same groups. Both, increase and decrease in the antioxidant enzymatic activities, showed significant differences with respect to the control group, being higher for the 0.032 mg l^-1 group. The Cr (VI) LC₅₀ was also estimated for these age groups, finding statistical differences among them. Even though adults exhibited higher responses, these enzymatic activity changes should not be interpreted as higher sensitivity, since the daphnids acute chromium toxicity followed a different pattern, with increasing LC₅₀ values according to age.

Key words

Redox environment, antioxidant enzymes, ageing process, Cladocera, Cr (VI)

Copyright ? 2011 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).