Peroxisome proliferator-activated receptor-γ (PPAR- γ), a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors, possesses anti-inflammatory properties. The purpose of the present study was to investigate the profile of PPAR- γ expression in the lung and to explore its functional significance in lipopolysaccharide (LPS)-induced acute lung injury. Thirty male Wistar rats were randomly assigned to one of the following five groups: saline control group and different LPS groups (2 h, 4 h, 6 h and 8 h after LPS 6 mg/kg i.v.). At predefined time points, blood samples were collected to measure plasma level of tumor necrosis factor (TNF)-α and lungs were removed to assay histopathological changes, wet-to-dry weight (W/D) ratio, myeloperoxidase (MPO) activity and TNF-α level. Expression of PPAR- γ and activation of nuclear factor (NF)- κB p65 in lung tissues were also examined in each group. LPS injection resulted in marked lung damage and elevated levels of W/D ratio and MPO activity in the lung. Increased levels of TNF-α were also observed in the plasma and lung. These inflammatory events were associated with reduced expression of PPAR-γ protein and with activation of NF-κB in the lung. Our data suggest that decreased expression of PPAR-γ protein in lungs may contribute to the ongoing pulmonary inflammation and tissue injury in endotoxemia.
5-aminolevulinic acid (ALA) is an essential precursor for the biosynthesis of tetrapyrrols such as heme and chlorophyll (Chl). Previous studies have focused mainly on promotive effects of exogenous ALA on plant growth, while regulatory mechanisms affecting Chl biosynthesis have been only partially discussed. In the present study, the ameliorative role of exogenous ALA was investigated on Chl and endogenous ALA biosynthesis in six-day-old etiolated oilseed rape (Brassica napus L.) cotyledons during the de-etiolation stage. We showed that exogenously applied ALA of a low dosage enhanced Chl and ALA accumulation in cotyledons, while 600 µM ALA treatment inhibited the accumulation of Chl and ALA severely. However, the gene expression levels of glutamyl-tRNA reductase (HEMA) and glutamate-1-semialdehyde aminotransferase (GSA) were not affected under either low or high ALA concentrations. Furthermore, water deficit induced by polyethylene glycol 6000 (PEG) suppressed the Chl and ALA accumulation in cotyledons, while the inhibition was partially alleviated in the cotyledons pretreated with ALA. The decrease in Chl biosynthesis induced by PEG stress was assumed to be related to downregulation of HEMA and Mg-chelatase ChlH (ChlH), and upregulation of ferrochelatase (FC) genes. Moreover, exogenously applied ALA did not show any effect on the expression of Chl synthesis-related genes under the PEG treatment. These results showed a difference in suppressing ALA synthesis due to the high concentration of ALA and PEG. Exogenously applied ALA did not affect the expression of HEMA and GSA, thus exogenous ALA regulated Chl synthesis not via the regulation of transcriptional level in ALA biosynthesis. However, the inhibition in Chl and endogenous ALA accumulation by the PEG treatment may be attributed to downregulation of HEMA and ChlH, and upregulation of FC., D. Liu, D. D. Kong, X. K. Fu, B. Ali, L. Xu, W. J. Zhou., and Seznam literatury
Xerophytic stomatal traits may help plants maintain photosynthetic rates under water deficit; however, such adaptations are not well understood. A pot experiment was conducted with two winter wheat cultivars (Pubing 143, Zhengyin 1) during the grain-filling period. Net photosynthetic rate (PN) and chlorophyll (Chl) content were significantly less affected by water deficit in Pubing 143 than that in Zhengyin 1, and the variation in both PN and Chl content were more stable in spikes compared to flag leaves. At 18 days after anthesis, stomatal conductance of spikes in Pubing 143 were 28% lower than that of the control, while transpiration rate was 34% lower in Zhengyin 1 under water deficit. We provided the first evidence of amphistomatous stomata on the lemma of winter wheat spikes through scanning electron microscopic observations. The finding of the amphistomatous stomata is an important contribution to stomatal distribution and may help explain how wheat spikes can maintain high photosynthetic rates even under drought conditions., H. Ding, D. Liu, X. Liu, Y. Li, J. Kang, J. Lv, G. Wang., and Obsahuje bibliografii