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The microalga Haematococcus lacustris (formerly H. pluvialis) is able to accumulate high amounts of the carotenoid astaxanthin in the course of adaptation to stresses like salinity. Technologies aimed at production of natural astaxanthin for commercial purposes often involve salinity stress; however, after a switch to stressful conditions, H. lacustris experiences massive cell death which negatively influences astaxanthin yield. This study addressed the possibility to improve cell survival in H. lacustris subjected to salinity via manipulation of the levels of autophagy using AZD8055, a known inhibitor of TOR kinase previously shown to accelerate autophagy in several microalgae. Addition of NaCl in concentrations of 0.2% or 0.8% to the growth medium induced formation of autophagosomes in H. lacustris, while simultaneous addition of AZD8055 up to a final concentration of 0.2 µM further stimulated this process. AZD8055 significantly improved the yield of H. lacustris cells after 5 days of exposure to 0.2% NaCl. Strikingly, this occurred by acceleration of cell growth, and not by acceleration of aplanospore formation. The level of astaxanthin synthesis was not affected by AZD8055. However, cytological data suggested a role of autophagosomes, lysosomes and Golgi cisternae in cell remodeling during high salt stress.

Heavy metals (Fe, Zn, Mn, Cu, Ni, Co, Pb, and Cd) were analyzed in 61 samples of plant species of the family Cruciferae and 23 samples of North Caucasian soils developed on ultramafic, mafic, and felsic bedrocks. The study revealed the dependence between the chemical composition of plants, geochemical environments, and the taxonomic position of species. We identified two species, Arabis sagittata, an accumu lator of Zn, Cu, Ni, and Alyssum murale, a hyperaccumulator of Ni, which can be effective in phytoremedi ation of heavy metal contaminated soils.

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