Structural reconstruction of a membrane at absorption of Mn2+, Zn2+, Cu2+, and Pb2+ with green algae Chlorella vulgaris BEIJ.

Abstract

We investigated the structural and functional features of membranes at absorption of Mn 2+ , Zn 2+ , Cu 2+ and Pb 2+ by unicellular green algae Chlorella vulgaris Beij. The accumulation of metals ions is fluctuating. There are four stages: the stage of protective self-isolation of cells as a result of the primary stress response, the stage of the active accumulation (decrease in resistance and destruction of outer membrane), the stage of inhibition of the accumulation (formation of the secondary concentric membrane), and the stage of uncontrolled accumulation (destruction of secondary con- centric membrane). The process of a concentric double membrane system formation is universal and does not depend on the nature of the toxicant (biogenic Mn 2+ , Zn 2+ , and Cu 2+ , toxic Pb 2+ ). Kinetic parameters of accumu- lation (K m , V max , E a ) show that the process of absorption of ions Mn 2+ , Zn 2+ ,Cu 2+ , and Pb 2+ goes according to mixed type of inhibition and is deter- mined by the affinity of metal-binding proteins to ions, and after saturation of their binding sites the process becomes uncontrolled. During absorption of metals happens structural reconstruction the cell wall chlorella by form- ing double concentric membrane system, which is an adaptive mechanism for regulating the absorption of metals, which functions to further protect cells from toxic levels of metal.