Cell size, chlorophyll fluorescence and cadmium bioaccumulation between wild-type and mutant strains of Chlamydomonas reinhardtii upon exposure to cadmium

Heavy metal contamination presents a constant threat to biological systems. Simultaneously, heavy metals have become one of the major contaminants in the aquatic ecosystem. In this regard, the investigation of heavy metal-tolerance genes in algae is relevant. Chlamydomonas reinhardtii is a unicellular green alga, and an excellent model organism used in heavy metal studies. In C. reinhardtii, a novel gene designated as Cia7, was hypothesized to play a role in heavy metal homeostasis due to CIA7’s conserved cysteine-residue motif. This study compared two strains of C. reinhardtii, cc4425, the wild-type possessing the functional CIA7 protein and cc5013, the mutant strain possessing the disrupted cia7- gene. The hypothesis was that the expression of Cia7 contributes to an increased cadmium (Cd)-tolerance in C. reinhardtii. The Cd-tolerance would be described by physiological markers of microalgae health, and by intracellular accumulation of the metal. Methods: The objectives of this study w...