Responses of the Antarctic microalga Koliella antarctica (Trebouxiophyceae, Chlorophyta) to cadmium contamination

Abstract

Ultrastructural and physiological effects of exposure to 1 ppm and 5 ppm of cadmium (Cd) on cultured cells of Koliella antarctica, a green microalga from Antarctica, were investigated. The amount of Cd in the alga rose with the increase of the metal concentration in the growth medium and most Cd remained outside the cells, bound to the components of the cell walls. The increase of Cd in the microalga was concomitant with the decrease of other elements, mainly calcium (Ca). Exposure to 1 ppm Cd slowed culture growth by inhibiting cell division and also caused the development of some misshapen cells with chloroplast showing disordered thylakoids. However, this concentration did not substantially affect the chlorophyll (Chl) content or photosystem (PS) activity. At 5 ppm, Cd cell growth suddenly stopped and some cells lysed. After a week of Cd contamination, the cells were enlarged and severely damaged. The chloroplasts showed great ultrastructural alterations and a reduced Chl content. Cd exposure negatively affected PSII, whose activity was almost completely lost after four days.

A novel species in the genusHeveochlorella(Trebouxiophyceae, Chlorophyta) witnesses the evolution from an epiphytic into an endophytic lifestyle in tree-dwelling green algae

“…Algae inhabit a wide variety of ecosystems including marine, freshwater, terrestrial and even extreme environments La Rocca et al, 2009). Some microalgae have established symbiotic associations with other organisms, such as Chlorella with green hydra and Paramecium bursaria (Kovačević et al, 2005(Kovačević et al, , 2007Kodama et al, 2007), in which the algae provide energy and even detoxification to the hosts (Pardy, 1976;Reisser, 1976;Kovačević et al, 2005).…”

Toxicity of cadmium and zinc on two microalgae, Scenedesmus obliquus and Desmodesmus pleiomorphus, from Northern Portugal

“…Aquatic ecosystems have become increasingly contaminated by heavy metals as a consequence of release of wastewaters containing such pollutants generated by anthropogenic sources; this poses a serious threat to human beings owing to their toxicity (even at minute concentrations), bioaccumulation and biomagnification in the food web (Herpin et al 1996;Mohammed and Markert 2006;la Rocca et al 2009). In fact, cadmium induces a wide spectrum of toxic effects upon plant physiology: it alters enzymatic activities via binding to functional groups or by displacing the metal therein (Báscik-Remisiewicz et al 2009;Sanitá di Toppi and Gabbrielli 1999).…”

Differential effects of cadmium and chromium on growth, photosynthetic activity, and metal uptake of Linum usitatissimum in association with Glomus intraradices

“…Decreased biomass of both inoculated and noninoculated plants under metal stress is due to the changes in various biochemical processes taking place at cellular and molecular level (Shanker et al 2005). Moreover, production of reactive oxygen species results in the blockage or inactivation of various enzymes and functional groups that regulate the normal functioning of plants (La Rocca et al 2009). The abovementioned findings were also obtained in the present research work.…”