Bioaccumulation and transformation of cadmium by Phaeodactylum tricornutum

Abstract

In this paper, we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration, which conformed to the prediction of the Free Ion Activity Model (FIAM). However, extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys, while intracellular uptake increased under Cys concentrations from the blank value to 4.45 A mu mol/L, and then tended to remain at the same level when the Cys concentration was greater than 4.45 A mu mol/L, and this deviated remarkably from the FIAM. The interactions of Cd with-Si-OH, -C-OH and NH2(CO)-OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2, Cd-EDTA and Cd-Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd, as is EDTA, but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore, the discovery of in vivo PCs and oxidized-PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs, reducing Cd-toxicity to P. tricornutum.National Natural Science Foundation of China [20535020, 20775062]; National 863 Hi-Tech Project of China [2006AA06Z404]; National Basic Research Program [2009CB421605

Free cadmium ions released from CdTe-based nanoparticles and their cytotoxicity on Phaeodactylum tricornutum

“…This was in accordance with the results observed in the cytotoxicity studies. Moreover, it should be noted that the uptake of Cd by P. tricornutum cells in the case of CdCl 2 exposure was the lowest compared with those of the CdTe-NPs, suggesting that P. tricornutum take up Cd 2+ and CdTe-NPs in different ways, in which that Cd 2+ is taken up via regulation of the ion-channels on the cell membrane 23 while CdTe-NPs are more easily taken up via cell endocytosis and release of Cd 2+ inside the cells thus causing damage.…”

“…Representing one of two major classes of diatoms, P. tricornutum is the most widely utilized as a model for studying the ecology, physiology, biochemistry and molecular biology of diatoms. 20,21 The tolerance of P. tricornutum to Cd 2+ has been studied, 22,23 and the results obtained suggest that P. tricornutum has a detoxifying mechanism for chelating Cd 2+ by in vivo synthesized phytochelatins (PCs) and proteins similar to that of higher plants. [24][25][26] However, the cytotoxicity of CdTe-NPs to this typical diatom has not been reported.…”

Investigation of Metal Toxicity on Microalgae Phaeodactylum tricornutum, Hipersaline Zooplankter Artemia salina, and Jellyfish Aurelia aurita

“… Comparison of the EC 50 values (mg/L) of Phaeodactylum tricornutum from other studies to the present study: ( a ) the EC 50 values of potassium dichromate at 72 h; ( b ) the Cu values at 72 h; ( c ) the Cd values at 72 h [ 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. …”

“…Some authors reported that, at 72 h, the Cd EC 50 value for P. tricornutum was as high as 22.39 mg/L, which reveals its excellent tolerance to Cd. Compared with other microalgae species, they reported lower EC 50 values: 1.87 µg/L of Cd for Scenedesmus quadricauda , 2.13 µg/L for Aulacoseira granulate , and 1.8 mg/L for Teraselmis gracilis [ 60 , 61 ]. According to our results, EC 50 for Cd(NO 3 ) 2 was far-removed from the reference values of the aforementioned papers.…”

Photocatalytical reduction of disulphide bonds in peptides on Ag-loaded nano-TiO2 for subsequent derivatization and determination

“…27 Under the flow injection mode, the reduction efficiencies of GSSG, vasopressin and insulin before and after UV-Ag/TiO 2 -HCOOH reduction with 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic Finally, we applied UV-Ag/TiO 2 -HCOOH together with DTNB derivatization to the determination of Cd-induced PCs in P. tricornutum. 28,29 Typical chromatograms obtained are shown in Fig. 3.…”