Increasing copper alters cellular elemental composition (Mo and P) of marine diatom

Abstract

The elemental composition (surface adsorbed and internalized fraction of Cu, Mo and P) in marine phytoplankton was first examined in cultures of the diatom Phaeodactylum tricornutum which were exposed to various levels of Cu concentrations ranging from 0.25 to 16 μmol/L with equivalent free [Cu2+] concentrations of 0.4–26 nmol/L. We observed an acceleration of algal growth rates (20–40%) with increasing ambient Cu levels, as well as slightly increased levels of internalized Cu in cells (2–13 × 10−18 mol/cell) although cellular Cu mostly accumulated onto the cell surface (>50% of the total: intracellular + surface adsorbed). In particular, we documented for the first time that the elemental composition (Mo and P) in algal cells varies dynamically in response to increased Cu levels: (1) Cellular P, predominantly in the intracellular compartment (>95%), shows with a net consumption as indicated by a gradual decrease with increasing [Cu2+] (120→50 × 10−15 mol P/cell) probably due to the fact that P, a backbone bioelement, is largely required in forming biological compartments such as cell membranes; and (2) cellular Mo, predominantly encountered in the intracellular compartment, showed up to tenfold increase in concentration in the cultures exposed to Cu, with a peak accumulation of 1.1 × 10−18 mol Mo/cell occurring in the culture exposed to [Cu2+] at 3.7 nmol/L. Such a net cellular Mo accumulation suggests that Mo might be specifically required in biological processes, probably playing a counteracting role against Cu.

Aerobic methane oxidation under copper scarcity in a stratified lake

“…Cu holds an important role in the photosynthetic and respiratory electron transport in phytoplankton 48 . Extended Redfield ratios of marine and freshwater phytoplankton centre around a total Cu content of 10 −16 –10 −18 mol cell −1 and a Cu:C ratio of ~10 −6 49 – 51 . This Cu:C ratio is similar to the theoretical stoichiometric ratio of a MOB cell, but phytoplankton, being significantly larger than MOB, contains much more Cu per cell (factor 10 2 –10 4 ).…”

The Toxicity of Copper to Crocosphaera watsonii and Other Marine Phytoplankton: A Systematic Review

“…Nitrogen and phosphorus availability altered Cu sensitivity in Ditylum brightwellii, Thalassiosira pseudonana, and Phaeodactylum tricornutum (Rijstenbil and Wijnholds, 1991;Rijstenbil et al, 1998;Wang D. et al, 2017), and mediation of Cu toxicity by high silicic acid concentrations was observed in T. pseudonana and Skeletonema costatum (Morel et al, 1978;Rueter et al, 1981). Likewise, the availability of other trace metals can ameliorate Cu toxicity.…”

Increasing Temperature Alters the Effects of Extracellular Copper on Thalassiosira Pseudonana Physiology and Transcription

“…Cu is essential for many physiological processes in phytoplankton, including electron-transfer reactions and high-affinity Fe transport systems, therefore low-Cu concentrations can also limit phytoplankton growth, as observed in the coccolithophore and T. oceanic [7]. Therefore, slight increases in ambient Cu concentrations have been shown to trigger the growth of P. tricornutum [25]. We found that increased Cu concentrations appeared to stimulate the growth of T. pseudonana at lower concentrations, which is consistent with previous studies [43,44].…”

“…Consequently, diatoms were used as optimal-biological models to investigate ecotoxicological and environmental effects arising from stressors on marine ecosystems [21][22][23]. Cu influences phytoplankton growth [24,25] and cellular-elemental stoichiometry, as well as a range of biochemical process such as pigmentation, photosynthesis and biochemical composition [26]. Furthermore, variation in physicochemical factors including temperature, salinity and pH, can impose additional stress on marine organisms, while also influencing metal contaminants, thereby affecting their availability and toxicity to organisms.…”