Differential responses to cadmium induced oxidative stress in marine macroalga Ulva lactuca (Ulvales, Chlorophyta)

Manoj Kumar, Puja Kumari, Vishal Gupta, P. A. Anisha, C. R.K. Reddy, Bhavanath Jha

Research output: Contribution to journalArticlepeer-review

76 Citations (Scopus)

Abstract

This study describes various biochemical processes involved in the mitigation of cadmiumtoxicity in green alga Ulva lactuca. The plants whenexposed to 0.4 mM CdCl2 for 4 days showed twofold increase in lipoperoxides and H2O2 content that collectively decreased the growth and photosynthetic pigments by almost 30% over the control. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione peroxidase (GPX) enhanced by twofold to threefold and that of catalase (CAT) diminished. Further, the isoforms of these enzymes, namely, Mn-SOD (̃85 kDa), GR (̃180 kDa) and GPX (̃50 kDa) responded specifically to Cd2+ exposure. Moreover, the contents of reduced glutathione (3.01 fold) and ascorbate (1.85 fold) also increased substantially. Lipoxygenase (LOX) activity increased by two fold coupled with the induction of two new isoforms upon Cd2+ exposure. Among the polyunsaturated fatty acids, although n - 3 PUFAs and n - 6 PUFAs (18:3n - 6 and C18:2n - 6) showed relatively higher contents than control, the latter ones showed threefold increase indicating their prominence in controlling the cadmium stress. Both free and bound soluble putrescine increased noticeably without any change in spermidine. In contrast, spermine content reduced to half over control. Among the macronutrients analysed in exposed thalli, the decreased K content was accompanied by higher Na and Mn with no appreciable change in Ca, Mg, Fe and Zn. Induction of antioxidant enzymes and LOX isoforms together with storage of putrescine and n - 6 PUFAs in cadmium exposed thallus in the present study reveal their potential role in Cd 2+ induced oxidative stress in U. lactuca.

Original languageEnglish
Pages (from-to)315-325
Number of pages11
JournalBiometals
Volume23
Issue number2
DOIs
Publication statusPublished - Apr 2010

Keywords

  • Antioxidant enzymes
  • Cadmium
  • LOX
  • Minerals
  • Oxidative stress
  • PUFAs
  • Ulva lactuca

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