No abstract available

No abstract available

[en] The absorption spectra of model 2-Fe ferredoxins are examined within the Intermediate Neglect of Differential Overlap method parametrized for spectroscopy utilizing a methodology developed earlier based on the restricted open-shell Hartree-Fock method and a subsequent configuration interaction. We demonstrate that this approach, that estimates the low energy spectroscopy of low-spin ground state complexes from simpler calculations assuming that the ground state is the corresponding high-spin complex, successfully reproduces the ligand-to-metal charge-transfer spectra of compounds that contain two weakly coupled transition metal atoms

[en] This study investigated the kinetics of Cd bioaccumulation, detoxification, subcellular distribution, and efflux in the nereid polychaete Perinereis aibuhitensis after Cd pre-exposure. Cd pre-exposure increased the Cd body burden in the worms, but did not affect the overall Cd uptake and efflux rates and metallothionein-like protein (MTLP) concentrations. During short-term exposure to dissolved Cd, Cd in the cytosolic fraction increased after Cd pre-exposure, and this fraction also increased during the Cd efflux period, indicating that the insoluble fraction of Cd was presumably lost at a faster rate than the loss of cytosolic Cd. Even though the MTLP concentration remained comparable after Cd pre-exposure, both the MTLP synthesis rate and the degradation rate increased, thus leading to a high MTLP turnover in the Cd-exposed worms. However, Cd uptake and efflux into different protein size fractions did not follow the patterns of MTLP synthesis and degradation, strongly suggesting that Cd kinetics is decoupled from the MTLP kinetics in the worms. Our study adds to an increasing body of evidence on the complicated relationship between metal biokinetics and MTLP kinetics in different groups of marine invertebrates which have strong contrasts in their metal handling strategies

[en] A previous study on transient expression of oil palm tissues has shown that the oil palm metallothionein- like type 3 (MT3-A) gene promoter is specifically expressed in the mesocarp and not in other tissues. This study was conducted to determine whether or not Arabidopsis can be used as a model system to study oil palm promoter. Functional characterisation of the oil palm MT3-A promoter was performed using promoter: GUS fusion analysis in transgenic Arabidopsis. The localisation of beta-glucuronidase (GUS) expression in several different tissues of transgenic Arabidopsis homozygous lines driven by the oil palm MT3-A promoter was determined. Histochemical GUS analysis in transgenic Arabidopsis revealed the highest expression in the cotyledon and hypocotyls as well as at the early stage of plant development and gradually decreased as the plant grew. Lower expression was detected in organs of mature plant and no expression was observed in reproductive tissues. This observation may suggest that MT3-A promoter might be involved during early stage of plant development. Since we use Arabidopsis which is neither a fruit nor mesocarp plant to check mesocarp-specific promoter it might not give a faithful pattern of expression but it may be suited to study oil palm specific promoter derived from other tissues. (author)

[en] A mild and novel process including on one-step chromatography was developed for the preparation of transferrin reference material with high purity.And function from Cohn fraction IV, by product of the Cohn fraction process.The method we have established is simple in operation and easy to enlarge.The transferrin product obtained with purity greater than 93% and a yield above 85%. Then the Tf secondary structure as well as function evaluated by circular dichroism (CD) proved no significantly varied. (paper)

[en] Metallothioneins are the proteins containing seven Cd atoms in tetrahedral arrangement of S atoms. For this compound full multiple scattering XAFS calculations have been used as a tool for verification of structural models generated using molecular dynamic. To determine the sensitivity of the spectrum to different structural parameters and to check does the best-fit XANES spectrum correspond to the correct structure of the complex we have tested method for Cd(SPh)₄ model compound

[en] Short communication

[en] Subcellular metal distribution has received increasing attention in aquatic toxicology studies, but the relationship between metal distribution and metal biokinetics remains largely unexplored. A series of short-term experiments on different concentrations of dissolved and dietary metals and on metal elimination were conducted to investigate the dynamics of subcellular distribution of Cd and Zn in the scallop Chlamys nobilis, a bivalve species that is known to accumulate very high concentrations of Cd and Zn in its tissues. Our results showed that, in general, both Cd and Zn were sequestered in insoluble forms (organelles, metal-rich granules, and cellular debris). The main binding pool for the newly acquired metals was organelles for Cd and cellular debris for Zn. Metallothionein-like protein (MTLP) was the most important storage pool for Cd in the scallops. Storage in the non-toxic form both in organelles and MTLP instead of through exocytosis was the major detoxification strategy to control Cd and accounted for the low efflux rate of Cd from scallops. In contrast to Cd, the main binding pool for Zn was cellular debris. Significant changes were found in the scallops when they were challenged with different concentrations of metals in the aqueous and food phases. Such changes provide important information on how scallops handle metals when there is increasing metal uptake. The redistribution of Zn among each subcellular compartment was much faster than the redistribution of Cd, suggesting an effective regulation mechanism for Zn in scallops. Thus, knowing subcellular metal distribution helps in studying the toxicity of both waterborne and dietborne metals

[en] Yellow-lupin (Lupinus luteus L.) was grown on soils contaminated with heavy metals during two parallel studies. In the first one, the soil was contaminated by industrial activities whereas, in the second one, the soil was artificially contaminated with a single metal including Cd, Pb, Zn, Ni (in nitrate form), and Ag (in nitrate and nanoparticles form). The study was performed to assess a plant’s response to contamination including its antioxidative response and molecular mechanisms involved in metal detoxification through the expression level of metallothioneins (MTs). Overall, the study provided insights into identification and validation of housekeeping genes (HKG) in L. luteus under exposure to metal stress and showed the effects of selected heavy metals and silver nanoparticles on the expression of metallothioneins, the activity of guaiacol peroxidase (GPX) and bioaccumulation of metals in leaves of L. luteus. As such, HKG validation using BestKeeper, NormFinder, and geNorm software allowed for the selection of four most stable reference genes in a context metal contamination for the selected plant. Moreover, a significant increase in the expression levels of MT was observed in plants grown under heavy metal stress and none on plants grown on 25 mg kg⁻¹ of silver nanoparticles. Also, the GPX activity and MT expression showed statistically significant changes between different conditions and doses which means that they can be used as highly sensitive stress markers for planning the phytoremediation process on a large scale.