Heavy Metal Detoxification in Eukaryotic Microalgae
Heavy metal detoxification in eukaryotic microalgae
Hugo Virgilio Perales-Vela, Julia´n Mario Pen˜a-Castro,
Rosa Olivia Can˜izares-Villanueva *


Abstract
Microalgae are aquatic organisms possessing molecular mechanisms that allow them to discriminate non-essential heavy metals from those essential ones for their growth. The different detoxification processes executed by algae are reviewed with special emphasis on those involving the peptides metallothioneins, mainly the post transcriptionally synthesized class III metallothioneins or phytochelatins. Also, the features that make microalgae suitable organisms technologies specially to treat water that is heavily polluted with metals is
discussed.
2005 Elsevier Ltd. All rights reserved.

Contents
1. Introduction
2. General characteristics of MtIII
2.1. General structure
2.2. Identification of PCS genes
2.3. Class III metallothionein biosynthesis and regulation
2.4. Sulfide ions and metallothionein function
2.5. Sequestration and compartamentalization to the vacuole
3. Class III metallothionein (MtIII) in algae
3.1. Synthesis
3.2. Physiological function and ecological importance
3.3. Sulfide ions
3.4. Sequestration into the vacuole
3.5. Sequestration to the chloroplast and mitochondria
3.6. The chain size
3.7. MtIII and other related mechanisms for heavy metal detoxification
3.8. Functional genomics of heavy metal stress in algae
4. Gene encoded metallothioneins in algae
5. Heavy metal removal by microalgae
5.1. Heavy metals in waste water
5.2. Algae-based biotechnologies for heavy metal remediation
5.3. Capability of different microalgal species to remove heavy metals
6. Conclusions
Acknowledgements
References
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