We studied cadmium toxicity in murine hepatocytes in vitro. Cadmium effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with a fluorescent probe, Fluo-3/AM. The results showed that administration of cadmium chloride (CdCl2, 5, 10, 25 μM) resulted in a dose-dependent decrease of hepatocyte viability and an elevated aspartate aminotransfe rase (AST) activity in the culture medium (p<0.05 for 25 μM CdCl2 vs. control). Significant increases of lactate dehydrogenase (LDH) activities in 10 and 25 μM CdCl2-exposed groups were observed (p<0.05 and p<0.01, respectively). A greatly decreased albumin content and a more malondialdehyde (MDA) formation also occurred after CdCl2 treatment. The Ca2+ concentrations in the culture medium of CdCl2-exposed hepatocytes were significantly decreased, while [Ca2+]i appeared to be significantly elevated (p<0.05 or p<0.01 vs. control). We found that in Ca2+-containing hydroxyethyl piperazine ethanesulfonic acid-buffered salt solution (HBSS) only, CdCl2 elicited [Ca2+]i increases, which comprised an initially slow ascent and a strong elevated phase. However, in Ca2+-containing HBSS with addition of 2-aminoethoxydiphenyl borane (2-APB), CdCl2 caused a mild [Ca 2+] i elevation in the absence of an initial rise phase. Removal of extracellular Ca2+ showed that CdCl2 induced an initially slow [Ca2+]i rise alone without being followed by a markedly elevated phase, but in a Ca2+-free HBSS with addition of 2-APB, CdCl2 failed to elicit the [Ca2+]i elevation. These results suggest that abnormal Ca2+ homeostasis due to cadmium may be an important mechanism of the development of the toxic effect in murine hepatocytes. [Ca2+]i elevation in acutely cadmium-exposed hepatocytes is closely related to the extracellular Ca2+ entry and an excessive release of Ca2+ from intracellular stores., S. S. Wang, L. Chen, S. K. Xia., and Obsahuje bibliografii a bibliografické odkazy
According to previous studies, integrins play an important role in the mechanotransduction. The aim of this study was to examine the role of integrin subunits and its down-stream signaling molecules in the cyclic hydrodynamic pressure-induced proliferation of human bladder smooth muscle cells (HBSMCs) cultured in scaffolds. The HBSMCs cultured in scaffolds were subjected to four different levels of cyclic hydrodynamic pressure for 24 hours, which were controlled by a BOSE BioDynamic bioreactor. Flow cytometry was used to examine cell cycle distribution. Real-time RT-PCR and western blotting were used to examine the expression levels of integrin subunits and their downstream signaling molecules. Integrin α 5 siRNA was applied to validate the role of integrin α 5 in cell proliferation. Here, we showed that cyclic hydrodynamic pressure promoted proliferation of HBSMCs. The cyclic hydrodynamic pressure also increased expression of integrin α 5 and phosphorylation of FAK, the key mediator of integrin α 5 signaling, but not that of integrin α 1, α 3, α 4, α v, β 1 and β 3. Moreover, inhibition of integrin α 5 decreased the level of p-FAK and abolished proliferation of HBSMCs stimulated by cyclic hydrodynamic pressure. Taken together, we demonstrate for the fi rst time that the integrin α 5-FAK signaling pathway controls the proliferation of HBSMCs in response to cyclic hydrodynamic pressure., T.-Q. Wei ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
B cell-activating factor belonging to the TNF family (BAFF, also called BLyS, TALL-1, zTNF-4, or THANK) is an important survival factor for B lymphocytes. In this study, we injected mouse abdominal cavity with human soluble BAFF (hsBAFF, 0.01, 0.1, 0.5, 2 mg/kg body mass) synthesized in Escherichia coli. On the 8th day after injection, we investigated the effects of hsBAFF on immune functional activities of splenic B lymphocytes, CD4+ and CD8+ T lymphocytes and natural killer (NK) cells in mice. The results showed that B lymphocyte proliferation significantly increased in hsBAFF-treated groups with dosages of 0.1 mg/kg (p<0.05), 0.5 and 2 mg/kg (p<0.01). We observed a dose-dependent increase of CD4+ T lymphocyte percentage and significantly higher values in 0.5 and 2 mg/kg hsBAFF-treated groups (p<0.05 and p<0.001, respectively) compared to control group, but CD8+ T lymphocyte percentage remained unchanged. The ratio of CD4+ to CD8+ T lymphocytes rose with increasing hsBAFF dosage (p<0.05 for 2 mg/kg hsBAFF vs. control). Significantly stronger NK cell activities were found in 0.5 and 2 mg/kg hsBAFF-treated groups (p<0.05). The main finding of this study is that the hsBAFF can enhance immune responses in the body by increasing B lymphocyte and CD4+ T lymphocyte function as well as elevating NK cell activity.
We studied hsBAFF activity in in vitro mouse splenic B cells. hsBAFF effects on intracellular free Ca 2+ concentration ([Ca 2+ ] i ) were assayed, using a laser scanning confocal microscope with fluorescent probe, Fluo-3/AM. We showed that treatment of B cells with 0.5-5 μ g/ml hsBAFF resulted in significantly higher [Ca 2+ ] i levels in a dose-dependent fashion at 12 and 24 h, respectively (p<0.05 or p<0.01 vs. control). Furthermore, we noticed that 2.5 μ g/ml hsBAFF-treated cells were significantly resistant to decrease of cellular viability induced by thapsigargin (Tg), an endoplasmic reticulum (ER) Ca 2+ -ATPase inhibitor (p<0.05 hsBAFF plus Tg group vs. Tg group). Thus hsBAFF may promote B cell survival by direct upregulation of [Ca 2+ ] i physiological homeostasis contri buting to prevention of [Ca 2+ ] i dysfunction. Using immunocytochemistry and Western blot analysis, we found that the activation of ERK1/2 due to hsBAFF was triggered by a [Ca 2+ ] i -dependent pathway, leading to elevation of B cell proliferation. This is supported by the findings that intracellular Ca 2+ chelator BAPTA/AM attenuated phosphorylated ERK1/2 expression and cell proliferation in hsBAFF-stimulated B cells. hsBAFF-stimulated B cell proliferation was obviously reduced by mitogen extracellular kinase 1/2 (MEK1/2, upstream of ERK1/2) inhibitor U0126. Taken together, the main finding of this study is that hsBAFF elicits higher but homeostatic [Ca 2+ ] i levels, which regulates ERK1/2 activity and cell proliferation in in vitro B cells., J. Q. Liang, W. Zhang, L. Wen, W. Gao, S. Q. Zhang, L. Chen., and Obsahuje bibliografii
The Amur Grape (Vitis amurensis Rupr.) cultivars ’shuangFeng’ and ‘ZuoShanyi’ were grown in shelter greenhouse under natural sunlight and subjected to drought. Sap flow rate, net photosynthetic rate (PN), and chlorophyll (Chl) fluorescence were measured on Amur Grape leaves subjected to different drought treatments. Significant decreases in P N were associated with increasing intercellular CO2 concentration (Ci), suggesting that the reduction in PN was caused by nonstomatal limitation. Analysis of OJIP transients according to the JIP-test protocol revealed that specific (per PSII reaction center) energy fluxes for light absorption, excitation energy trapping and electron transport have significantly changed. The appearance of a pronounced K-step and J-step in polyphasic rise of fluorescence transient suggested the oxygen-evolving complex and electron transport were inhibited. Drought stress has relatively little effect on the parameter maximal quantum yield of PSII photochemistry (Fv/Fm), but the performance index (PIABS) is more sensitive in different drought treatment. There are cultivar differences in the response of PSII activity to drought, the photosynthetic apparatus of ‘ZuoShanyi’ cultivar is more resistant to drought than that of ‘ShuangFeng’, and JIP-test could be a useful indicator for evaluation and selection to drought tolerance., Z. X. Wang ... [et al.]., and Obsahuje bibliografii
We examined the physiological and biochemical responses of two halophytic grasses with different photosynthetic pathways, Puccinellia tenuiflora (C3) and Chloris virgata (C4), to saline-alkaline stresses. Plants were grown at different Na2CO3 concentrations (from 0 to 200 mM). Low Na2CO3 (< 12.5 mM) enhanced seed germination and plant growth, whereas high Na2CO3 concentrations (> 100 mM) reduced seed germination by 45% in P. tenuiflora and by 30% in C. virgata. Compared to C. virgata, P. tenuiflora showed lower net photosynthesis, stomatal conductance, intercellular CO2 concentration, and water-use efficiency under the same treatment. C. virgata exhibited also relatively higher ATP content, K+ concentration, and the K+/Na+ ratio under the stress treatments implying that salt tolerance may be the main mechanism for salt resistance in this species. Our results demonstrated that the C. virgata was relatively more resistant to saline-alkaline stress than the co-occurring P. tenuiflora; both two species adapt to their native saline-alkaline habitat by different physiological mechanisms., C. Y. Guo, X. Z. Wang, L. Chen, L. N. Ma, R. Z. Wang., and Obsahuje bibliografii