Salinity-induced chemical, mechanical, and behavioral changes in marine microalgae

Abstract

This study examines how salinity reduction triggers the response of three marine microalgae at the molecular and unicellular levels in terms of chemical, mechanical, and behavioral changes. At the lowest salinity, all microalgal species exhibited an increase in membrane sterols and behaved stiffer. The glycocalyx-coated species Dunaliella tertiolecta was surrounded by a thick actin layer and showed the highest physiological activity, negatively affecting cell motility and indicating the formation of the palmella stage. The lipid content of membrane and the hydrophobicity of cell were largely preserved over a wide range of salinity, confirming the euryhaline nature of Dunaliella. The species with calcite-encrusted theca Tetraselmis suecica exhibited the highest hydrophobicity at the lowest salinity of all cells examined. At salinity of 19, the cells of T. suecica showed the lowest growth, flagellar detachment and the lowest cell speed, the highest physiological activity associated with a dense network of extracellular polymeric substances, and a decrease in membrane lipids, which could indicate develepment of cyst stage. The organosilicate encrusted species Cylindrotheca closterium appeared to be salinity tolerant. It behaved hydrophobically at lower salinity, whereas becoming hydrophilic at higher salinity, which might be related to a molecular change in the released biopolymers. This study highlighted the interplay between chemistry and mechanics that determines functional cell behavior and shows that cell surface properties and behavior could serve as stress markers for marine biota under climate change. Graphical Abstract

Nanoplastic-Induced Nanostructural, Nanomechanical, and Antioxidant Response of Marine Diatom Cylindrotheca closterium

“…Another important property of the cell surface that may change, depending on growth conditions, is the rigidity of the cell wall. Indeed, several studies have shown that a specific stress or a change in environmental conditions (such as a change in pH, temperature, or salinity) can have an important effect on the composition or remodeling of the cell wall, thereby changing its nanomechanical properties [60][61][62][63][64][65][66]. Our nanoindentation measurements, performed on C. closterium cells exposed to nanoplastics, showed a significant decrease in cell wall rigidity compared to cells grown without nanoplastics (Figure 7).…”

“…A change in the Young modulus of cells was also observed when the pH of the culture medium changed, and it increased significantly at a higher pH [61]. In addition, previous studies by our group [64,65,68] have shown that the exposure of cells to temperature stress, salinity stress, and cadmium causes changes in cell rigidity, as a consequence of a molecular modification to the cell barrier. It is therefore not surprising that exposure to nanoplastics also alters the nanomechanical properties of cells.…”

What are the criteria for morphological cell death inDunaliella salina?

“…Glycocalyx acts as an intermediate and protects cell membrane against direct physical forces and environmental stresses allowing it to maintain its integrity. The attachment of cell membrane to cell cover takes place by membrane proteins (74)(75). D. salina alga which lives in hypersaline environments, adjusts itself to these ecosystems by cell plasma membrane protein kinases and also by internal glycerol synthesis which help cells to make osmotic adjustment to high external saline conditions (76).…”

A Green Revolution in Antioxidant Research: Harnessing Microalgae for Wellness and Longevity

“…Microalgae have different tolerance levels for salinity. Changes in salinity can affect the production of antioxidants in marine and halotolerant microalgae [34].…”