Acclimatization of Thalassiosira pseudonana photosynthetic membranes to environmental temperature changes

Abstract

The greenhouse effect results in warming the planet's surface and a higher ocean heat content. It causes changes of the water circulation frequency and turbulent mixing, delivering warm water, phytoplankton nutrients and CO2 from deeper layers of water to the water surface. All of these changes can have an impact on Earth's ecosystems. In the present study the effect of changing environmental temperature on a model diatom species, Thalassiosira pseudonana was tested under laboratory conditions. The purpose of the work was to analyze the temperature effect on fluidity and chemical composition of the thylakoid membranes. The photosynthetic activity and photosynthetic pigment contents of diatoms adapted to different temperatures were also determined. Our result show decreases of the growth rate and chlorophylls concentration in diatom cells cultured at lower temperature. It was also detected that increases of the polyunsaturated and decreases of saturated fatty acids, as well as changes in lipids:proteins ratio, resulted in stabilization of the thylakoid membranes fluidity and photosynthetic efficiency (Fv/Fm) in a physiological range of the temperature. The result show that the regulation of the concentration and interaction of fatty acids, proteins and pigments is the most important factor in the adaptation strategies of diatoms to the environmental temperature changes. Additionally, the regulation of membrane fluidity was demonstrated as important mechanism of the diatom adaptation to greenhouse effects. We also postulate that the adaptive mechanisms to temperature changes are differently expressed in the polar or hydrophobic regions of photosynthetic membranes.