Investigation of toxic effect of mercury on Microcystis aeruginosa: Correlation between intracellular mercury content at single cells level and algae physiological responses

Transformation of Mercuric Ions to Mercury Nanoparticles in Diatom Chaetoceros curvisetus

“…This ensured intracellular Hg(II) concentrations were environmentally relevant concentrations, owing to the bioaccumulation of cells in a realistic environment. 17,18,38 Chaetoceros curvisetus in the midexponential growth phase was harvested by centrifugation (2000g, 25 °C, 10 min), then rinsed with 5 mL of PBS (10 mmol L −1 ) three times, and finally resuspended in the exposure medium with the addition of HgCl 1, 2, 3, and 4 days. Similarly, to investigate Hg accumulation and transformation with concentration changes, Chaetoceros curvisetus was exposed to 0.5, 1.0, 5.0, 10.0, and 100.0 μg L −1 Hg(II) for 4 days.…”

“…To investigate the sizes and distribution of particulate HgS, diatom Chaetoceros curvisetus was subjected to acute exposure to 0.5–100.0 μg L –1 Hg­(II) at one time and without changing the medium during exposure. This ensured intracellular Hg­(II) concentrations were environmentally relevant concentrations, owing to the bioaccumulation of cells in a realistic environment. ,, Chaetoceros curvisetus in the midexponential growth phase was harvested by centrifugation (2000 g , 25 °C, 10 min), then rinsed with 5 mL of PBS (10 mmol L –1 ) three times, and finally resuspended in the exposure medium with the addition of HgCl 2 . To investigate Hg accumulation and transformation with time extension, Chaetoceros curvisetus was exposed to 10.0 μg L –1 Hg­(II) for 0, 1, 2, 3, and 4 days.…”

“…Also, regarding the total Hg, Hg(II) was rapidly accumulated and adsorbed by diatom cells after a short period of Hg(II) exposure on day 0, consisting with the rapid adsorption of Hg (30 min) in previous studies. 38,45 In the next few days, most of the total Hg(II) was intracellular Hg (59−71% of total Hg) (Figure S4B and Table S4). The diatom could uptake inorganic Hg by passive transport, and around 91% of inorganic Hg was distributed on the inner membrane.…”

Bioconcentration of Inorganic and Methyl Mercury by Algae Revealed Using Dual-Mass Single-Cell ICP-MS with Double Isotope Tracers

“…In previous single-cell studies of algae, the cells were directly resuspended in UPW without considering the impact on their physiological states and morphology. 17,23,36 Resuspension of freshwater algae in UPW seemed not to significantly affect their cellular granularity and size (Figure S7). Nevertheless, the time-resolved profiles of endogenous P signals showed that the fixation of freshwater algae facilitated a lower baseline and, thus, a higher signal-to-noise ratio (Figure S8A,B).…”

“…Cell events were identified according to the established iteration algorithm (μ + 5σ). 17,22 Hg standard solutions of natural isotopic abundance were measured in the dual-mass time-resolved mode to plot external standard curves for 199 Hg and 201 Hg. Accordingly, the Hg masses (m) on single algae cells (fg cell −1 ) were calculated by the following equation…”