Algal cell response to laboratory-induced cadmium stress: a multimethod approach

Abstract

We examined the response of algal cells to laboratory-induced cadmium stress in terms of physiological activity, autonomous features (motility and fluorescence), adhesion dynamics, nanomechanical properties and protein expression by employing a multimethod approach. We develop a methodology based on the generalized mathematical model to predict free cadmium concentrations in culture. We used algal cells of Dunaliella tertiolecta, which are widespread in marine and freshwater systems, as a model organism. Cell adaptation to cadmium stress is manifested through cell shape deterioration, slower motility and an increase of physiological activity. No significant change in growth dynamics showed how cells adapt to stress by increasing active surface area against toxic cadmium in the culture. It was accompanied by an increase in green fluorescence (most likely associated with cadmium vesicular transport and/or beta carotene production), while no change was observed in the red endogenous fluorescence (associated with chlorophyll). To maintain the same rate of chlorophyll emission, the cell adaptation response was manifested through increased expression of the identified chlorophyll-binding protein(s) that are important for photosynthesis.Since production of these proteins represents cell defence mechanisms, they may also signal the presence of toxic metal in seawater. Protein expression affects the cell surface properties and therefore the dynamics of the adhesion process. Cells behave stiffer under stress with cadmium and thus the initial attachment and deformation are slower. Physicochemical and structural characterizations of algal cell surfaces are of key importance to interpret, rationalize and predict the behaviour and fate of the cell under stress in vivo.

Biosensing the Presence of Metal Nanoparticles by Spectrally- and Time-Resolved Endogenous Fluorescence in Water Moss Fontinalis antipyretica

“…Heavy metals are known to affect the chloroplast ultrastructure, causing lipid peroxidation in photosynthetic membranes, degradation of photosynthetic pigments, inhibition of photosystem II (PSII) activity and electron transport, thus restraining the net photosynthetic rate [49]. Previously, we have demonstrated the sensitivity of marine algae Dunalliela tertiolecta to laboratoryinduced stress with heavy metal cadmium [19,33], with the role of stress-related light-harvesting complexes (LHC). The comparable effect can also be involved in the observed actions, but the exact mechanisms involved still remain to be elucidated.…”

“…Heavy metals enter into the aquatic system through the agricultural runoff and industrial discharges [32]. Previously, we have demonstrated the sensitivity of marine algae Dunalliela tertiolecta to laboratory-induced stress with heavy metal cadmium [19,33]. The study showed an appearance of the stressrelated light-harvesting complex (LHC), as well as changes at the endogenous fluorescence levels.…”

Structural Features of the Algal Cell Determine Adhesion Behavior at a Charged Interface

“…The higher stiffness of D. tertiolecta cells in the exponential growth phase reflected on the slower cell adhesion kinetics at the interface. On the other hand, Dunaliella cells′ adaptation response when exposed to heavy metal stresses manifested with a significant increase in stiffness due to the expression of surface proteins associated with the photosynthetic activity, which was reflected on slower initial attachment and deformation [37].…”

Short-term effect of cadmium on the motility of three flagellated algal species

“…Stock solutions of Cd(NO 3 ) 2 were added to cultures on 19 days after the inoculum to reach concentrations of 1 mg L −1 . The selected concentration of cadmium was chosen based on the calculation of the free Cd(II) using the generalised mathematical model for the complex formation of a single ligand with several trace metals (Ivošević DeNardis et al 2019). The cadmium concentration of 1 mg L −1 corresponds to the 600 μg L −1 of free Cd(II) which acts toxic to cells and causes the reduction in growth (Ivošević DeNardis et al 2019).…”

“…However, a lack of sufficient data precluded the statistical significance (Danilov and Ekelund 2001;Liu et al 2011). Recently, we reported that green alga Dunaliella tertiolecta survived long-term exposure to cadmium by sustaining healthy photosynthetic apparatus through an expression of membrane proteins and carotenoid production, increased physiological activity and cell stiffness, but with slower motility (Ivošević DeNardis et al 2019). Concurrently, the accumulation of cadmium in D. tertiolecta cells was detected by the secondary ion mass spectroscopy demonstrating the main entry pathway of toxic metal into food chains (Pavlinska et al 2020).…”