Cadmium is one of the most dangerous environmental pollutants, affecting, among other things, plant mineral composition. It easily interacts with iron, one of the most important elements for plant growth and metabolism. This interaction, including modifying effects of lowered or excessive Fe supply on Cd-exposed plants and its consequences for the photosynthetic apparatus is reviewed. The influence of modified Fe and Cd supply on the uptake of both metals, their distribution, plant growth, and photosynthesis is also explained. Moderate Fe excess has a beneficial influence on Cd-treated plants, resulting in more intensive growth, photosynthetic pigments accumulation, and more efficient light phase of photosynthesis. Nutrient-medium Fe deficiency increases plant susceptibility to Cd. The main open questions of Cd/Fe interaction are: (1) the strong Fe-dependency of Cd mobility within the plant, and (2) photosynthetic dark phase adaptation to Cd stress. and A. Siedlecka, Z. Krupa.
Thylakoid membranes (TM) of the cyanobacterium Synechococcus elongatus were exposed for 30 min to the influence of 0, 10, 100, and 1 000 mM CdCl2 (= Cd0, Cd10, Cd100, and Cd1000). Cd10 and Cd100 caused some increase in activity of photosystem 2, PS2 (H2O → DCPIP), while distinct inhibition was observed with Cd1000. We also observed a similar effect when measuring oxygen evolution (H2O → PBQ + FeCy). Chloroplasts of spinach (Spinacia oleracea L.) were incubated for 30 min with 0, 15, 30, and 60 mM CdCl2 (= Cd0, Cd15, Cd30, and Cd60). All concentrations studied inhibited the PS2 activity, the effect being stronger with increasing concentration of Cd2+. The photosynthetic oxygen evolution activity was also influenced most distinctly by the highest concentration employed, i.e. Cd60. Electrophoretic analysis of the protein composition of cyanobacterium TM showed chief changes in the molecular mass regions of Mr 29 000 and 116 000, while with spinach chloroplasts the most distinct differences were observed in the regions of Mr 15 000 and 50 000. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity in cyanobacterial spheroplasts still remained on the 40 % level in the case of Cd1000, but it decreased down to approx. 2.5 % in the Cd60 sample of spinach chloroplasts. and M. Nováková, E. Matějová, D. Sofrová.
The CD8+ natural killer (NK) subpopulation has recently been identified as a fast and reliable biodosimetric indicator within human peripheral blood mononuclear cells (PBMC) in vitro. In irradiated and subsequently cultivated PBMC, a decrease of the relative number of intact CD3-CD8+ lymphocytes 16 and 48 h after treatment has allowed for estimating the received dose in the range of 0 - 10 Gy and lethal/sublethal dose discrimination, respectively. Here we show that suitable biodosimeters can also be found in the peripheral blood B-cell compartment. Multiparameter flow cytometric analysis of irradiated and subsequently cultivated human PBMC revealed that both the CD27+ and CD21- B-cell subpopulations can be used as biodosimeters and the CD19+CD27+ lymphocytes have proved useful for retrospective determination of the received dose in the range of 0 - 6 Gy. In addition, several CD19+ lymphocyte subsets characterized by co-expression of CD21, CD27 and CD38 have been shown to bear biodosimetric potential, too. However, when important parameters like the original size within the CD19+ compartment, its radiation-induced changes and data variation had been taken into account, the CD27+ subpopulation proved superior to the other B-cell subpopulations and subsets. It appears that, in the dose range of 0 - 6 Gy, the relative decrease of CD27+ B lymphocytes provides more sensitive and reliable data than that of CD8+ NK-cells due mainly to lower data variation. In contrast to CD27+ B-cells, the proportions of CD27+ subpopulations of T-cells were not affected by irradiation. We have also proposed a simple experimental protocol based on full blood cultivation and three-color CD27/CD3/CD19 immuno-phenotyping as a time-saving and inexpensive approach for practical biodosimetric evaluations on simple, three-to-four color flow cytometers., Z. Řeháková, J. Šinkora, M. Vlková, D. Vokurková, J. Österreicher, J. Vávrová, D. Driák., and Obsahuje bibliografii a bibliografické odkazy
In the current study, we tested a hypothesis that CD36 fatty acid (FA) transporter might affect insulin sensitivity by indirect effects on FA composition of adipose tissue. We examined the effects of CD36 downregulation by RNA interference in 3T3-L1 adipocytes on FA transport and composition and on sensitivity to insulin action. Transfected 3T3-L1 adipocytes, without detectable CD36 protein, showed reduced neutral lipid levels and significant differences in FA composition when levels of essential FA and their metabolites were lower or could not be detected including gamma linolenic (C18:3 n6), eicosadienic (C20:2 n6), dihomo-gamma linolenic (C20:3 n6), eicosapentaenoic (EPA) (C20:5 n3), docosapentaenoic (DPA) (C22:5 n3), and docosahexaenoic (DHA) (C22:6 n3) FA. Transfected 3T3-L1 adipocytes exhibited a significantly higher n6/n3 FA ratio, reduced Δ5-desaturase and higher Δ9-desaturase activities. These lipid profiles were associated with a significantly reduced insulin-stimulated glucose uptake (4.02±0.1 vs. 8.42±0.26 pmol.10-3 cells, P=0.001). These findings provide evidence that CD36 regulates FA composition thereby affecting sensitivity to insulin action in 3T3-L1 adipocytes., K. Kontrová, J. Zídková, B. Bartoš, V. Skop, J. Sajdok, L. Kazdová, K. Mikulík, P. Mlejnek, V. Zídek, M. Pravenec., and Obsahuje bibliografii a bibliografické odkazy
Protective immunity against murine malaria infection depends largely on the establishment of effective Th1 immune response during the early stages of infection. Experimental data suggest that the death of Plasmodium yoelii 17XL (P.y 17XL) susceptible BALB/c mice results from the suppression of Th1 immune response mediated by CD4+CD25+Foxp3+regulatory T cells (Tregs). However, the mechanism by which Tregs regulate Th1 immune response is poorly understood. Since immunity is initiated by dendritic cells (DCs), we analysed DC responses to P.y 17XL in control and Treg-depleted BALB/c mice. Myeloid DC proliferation, phenotypic maturation and interleukin-12 (IL-12) production were strongly inhibited in control BALB/c mice. In contrast, plasmacytoid DC proliferation and IL-10 production were strongly enhanced in control BALB/c mice. In-vivo depletion of Tregs resulted in significantly reversed inhibition of DC response, which may contribute to the establishment of Th1 immune response, indicating that Tregs contribute to the suppression of Th1 immune response during malaria. These findings suggest Tregs contribute to prevent Th1 immune response establishment during the early stage of P.y 17XL infection by inhibiting DC response.