Experiments were conducted in the equatorial Pacific Ocean to assess role of Fe and grazing regulating use NO3− by phytoplankton community. Nitrate uptake rates situ slow because NH4+ concentrations inhibitory biomass was kept low grazing. When feeding grazers artificially suppressed, net growth rate increased, accumulated, consumed. Rapid [40 µmol (g Chl a)−1 h−1] decreased an order magnitude 1–2 d after added, demonstrating that these under physiological regulation elevated response...

Phytochelatin has been quantified in Thalassiosira weissflogii, a marine diatom after exposure to series of trace metals (Cd, Pb, Ni, Cu, Zn, Co, Ag, and Hg) at concentrations similar those the environment. Within range relevant natural waters, Cd, lesser extent Cu are most effective inducers phytochelatins. The generality this result was confirmed by short-term experiments with two other phytoplankton species. Quantification intracellular Zn shows that phytochelatin production does not...

Phytochelatins are metal-binding peptides produced enzymatically by higher plants, fungi, and algae in response to many metals, particularly Cd. We have studied phytochelatin production several marine phytoplankton exposed a range of free Cd ion concentrations. As result increased analytical resolution, we found that all the species contain phytochelatin, even when there is no added Cd, elevated concentrations induced at very low environmentally relevant (as as 10−12 M concn). In some but...

Phytochelatins are small metal-binding polypeptides synthesized by algae in response to high metal concentrations. Using a very sensitive HPLC method, we have quantified phytochelatins from phytoplankton laboratory cultures at environmentally relevant concentrations and marine field samples. Intracellular of phytochelatin, the diatom Thalassiosira weissflogii, exhibit distinct dose-response relation with free Cd2+ concentration medium--not total Cd(2+)--and detectable even when is less than...

Cadmium is one of the most toxic trace metals and induces high concentrations metal-binding polypeptide phytochelatin, (γ-Glu-Cys)nGly where n ≥ 2, in marine diatom Thalassiosira weissflogii. Here we show that at inorganic cadmium there an efflux from T. weissflogii so large over half taken up by cell returned to medium. At cadmium, also phytochelatin cell. The both stops when external concentration reduced. occurs a molar ratio approximately 4 γ-Glu-Cys subunits per stoichiometry similar...

Abstract The Thermobifida fusca cel6A gene encoding an endoglucanase was fused to three different downstream box (DB) regions generate genes with 14 amino acid fusions. DB‐Cel6A fusions were inserted into the tobacco ( Nicotiana tabacum cv. Samsun) chloroplast genome for protein expression. Accumulation of Cel6A in transformed leaves varied over approximately two orders magnitude, dependent on identity DB region open reading frame (ORF). Additionally, ORF affected accumulation aging leaves,...

ABSTRACT Phytochelatins are enzymatically synthesized peptides involved in metal detoxification and have been measured plants grown at very high Cd concentrations, but few studies examined the response of lower environmentally relevant concentrations. Using an ethylenediaminetetraacetic acid (EDTA)–buffered nutrient medium, we varied exposure phytochelatin glutathione concentrations romaine lettuce ( Lactuca sativa L. var. longifolia Lam. Parris Island) a flow‐through hydroponic (FTH)...

In surface seawater, dissolved copper (Cu) is predominantly bound by a small pool of strong ligands, with further complexation larger weaker ligands. Although the chemical structure both classes ligands observed in open ocean remains unknown, it believed that stronger are biological origin, and has been hypothesized they thiols. Using precolumn derivatization high‐performance liquid chromatography electrospray ionization ion‐trap mass spectrometry, we found ubiquitous coccolithophorid...

Cultures of the ubiquitous coccolithophore Emiliania huxleyi grown at field-relevant fixed free ion concentrations Cu, Cd, and Zn exude a broad array thiols, some which increase with increasing metal concentration. The primary thiols released are contingent on particular or combination metals added to culture media. Exposure Cu results in release arginine-cysteine, glutamine-cysteine, cysteine; Cd causes these glutathione be released; high synthesis exudation predominantly γ-glutamate-...

Emiliania huxleyi, a ubiquitous marine algae, was cultured under replete and Cu-limiting conditions to investigate Cu uptake strategies involving thiols associated redox reactions; comparisons model diatom, Thalassiosira pseudonana, were also drawn. Cu-limitation increased rates of cell surface reduction Cu(II) Cu(I) in E. huxleyi but not T. pseudonana. Furthermore, Cu-limited cells took up more when cysteine present compared no ligand added, although dependence on concentration observed. In...

Abstract The tace metal (Cu, Zn, Cd, Mn) and phytochelatin(an intracellular chelator for ions) cellular content were determined in phytoplankton samples originating from four lakes (Greifen, Sempach, Lucerne, Orta). differ their concentrations other conditions (pH, trophic state, organic matter). Total contents of Cu Cd related to the experimentally free ion concentration total Mn dissolved Mn. Zn was tightly regulated over a broad range [Zn 2+ ]. Phytochelatin measurable communities three...

The effect of metal interactions on phytochelatin production by marine phytoplankton has received little attention but yet is critical to understanding the biochemical this potentially important metal-binding ligand in field. Cd, Cu, and Zn additions were made singly combination three species laboratory cultures a natural algal assemblage from pristine coastal seawater. In intracellular varied with exposure demonstrated metal- concentration-dependent synergisms antagonisms. Most notably,...

Glutathione is an abundant intracellular thiol that involved in the detoxification of reactive oxygen species generated presence light. We used short‐term continuous cultures Emiliania huxleyi and Thalassiosira pseudonana to show a diurnal light cycle causes glutathione undergo at least twofold variations, with maximum concentrations occurring during periods. Cysteine also appear vary E. similar extent, highest night. A complementary field study conducted Salt Pond Falmouth, Massachusetts,...

Cadmium is a nonessential trace metal and frequent soil contaminant. Because plants vary in their accumulation of Cd, an understanding the specific processes that control uptake could reveal methods for reducing Cd levels edible plant tissues conversely increasing used phytoremediation. Phytosiderophores are iron chelators excreted by graminaceous under conditions limitation, but they also complex other metals including cadmium. Here we examine influence exposure on phytosiderophore...