Cyanidiales as Polyextreme Eukaryotes.

Cyanidiales were named enigmatic microalgae due to their unique polyextreme properties, considered for a very long time unattainable for eukaryotes. Cyanidiales mainly inhabit hot sulfuric springs with high acidity (pH 0-4), temperatures up to 56°C, and ability to survive in the presence of dissolved heavy metals. Owing to the minimal for eukaryotes genome size, Cyanidiales have become one of the most important research objects in plant cell physiology, biochemistry, molecular biology, phylogenomics, and evolutionary biology.

State 1 and State 2 in Photosynthetic Apparatus of Red Microalgae and Cyanobacteria.

Imbalanced light absorption by photosystem I (PSI) and photosystem II (PSII) in oxygenic phototrophs leads to changes in interaction of photosystems altering the linear electron flow. In plants and green algae, this imbalance is mitigated by a partial migration of the chlorophyll a/b containing light-harvesting antenna between the two photosystem core complexes. This migration is registered as fluorescence changes of the pigment apparatus and is termed the reverse transitions between States 1 and 2.

[Antenna replacement in the evolutionary origin of chloroplasts].

Endosymbiotic origin of chloroplasts from unicellular cyanobacteria is presently beyond doubt. Oxygenic photosynthesis is based on coordinated action of two photosystems (PS), PS I and PS II, cooperating with several variants of the pigment antenna. In cyanobacteria, red algae, and glaucophytes, phycobilisomes (PBS) act as antennae, while in terrestrial plants, as well as most macro- and microalgae antennae are formed by chlorophyll a/b- and chlorophyll a/c-containing proteins.

[Changes in parameters of Ascophyllum nodosum dark respiration induced by different salinities].

The changes in the rates of O2 consumption and CO2 release by Ascophyllum nodosum thalli in the dark were studied during a 12 day incubation at 34, 20, and 10/1000 salinity as well as at different pH. Depending on the initial pH of the medium, the algae demonstrated antipodal functional responses to the same salinities and, as a consequence, different capacity to overcome hypoosmotic stress. In addition, we observed a more pronounced effect of pH on the rate of O2 consumption than on the rate of CO2 release.

[The influence of salinity on the rate of dark respiration and structure of the cells of brown algae thallus from the Barents sea littoral].

We studied the changes in the rate of dark respiration (DR) and structure of the cells in Ascophyllum nodosum and Fucus vesiculosus thalluses during the incubation at 40, 34, 20, 10, and 2@1000 salinity for 14 days. The changes in salinity affect the rate of DR and the structure of the thallus apical cells: the organelles swell and later are destroyed. The effect of decreased salinity on the algae was more pronounced as compared to the increase.