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991.
992.
Bart M. G. Smits Jill D. Haag Anna I. Rissman Deepak Sharma Ann Tran Alexi A. Schoenborn Rachael C. Baird Dan S. Peiffer David Q. Leinweber Matthew J. Muelbl Amanda L. Meilahn Mark R. Eichelberg Ning Leng Christina Kendziorski Manorama C. John Patricia A. Powers Caroline M. Alexander Michael N. Gould 《PLoS genetics》2013,9(6)
993.
Jingwei Sheng Winston Shim Heming Wei Sze Yun Lim Reginald Liew Tien Siang Lim Boon Hean Ong Yeow Leng Chua Philip Wong 《Journal of cellular and molecular medicine》2013,17(10):1345-1354
Cardiac fibroblasts are crucial in pathophysiology of the myocardium whereby their aberrant proliferation has significant impact on cardiac function. Hydrogen sulphide (H2S) is a gaseous modulator of potassium channels on cardiomyocytes and has been reported to attenuate cardiac fibrosis. Yet, the mechanism of H2S in modulating proliferation of cardiac fibroblasts remains poorly understood. We hypothesized that H2S inhibits proliferative response of atrial fibroblasts through modulation of potassium channels. Biophysical property of potassium channels in human atrial fibroblasts was examined by whole‐cell patch clamp technique and their cellular proliferation in response to H2S was assessed by BrdU assay. Large conductance Ca2+‐activated K+ current (BKCa), transient outward K+ current (Ito) and inwardly rectifying K+ current (IKir) were found in human atrial fibroblasts. Current density of BKCa (IC50 = 69.4 μM; n = 6), Ito (IC50 = 55.1 μM; n = 6) and IKir (IC50 = 78.9 μM; n = 6) was significantly decreased (P < 0.05) by acute exposure to NaHS (a H2S donor) in atrial fibroblasts. Furthermore, NaHS (100–500 μM) inhibited fibroblast proliferation induced by transforming growth factor‐β1 (TGF‐β1; 1 ng/ml), Ang II (100 nM) or 20% FBS. Pre‐conditioning of fibroblasts with NaHS decreased basal expression of Kv4.3 (encode Ito), but not KCa1.1 (encode BKCa) and Kir2.1 (encode IKir). Furthermore, H2S significantly attenuated TGF‐β1–stimulated Kv4.3 and α‐smooth muscle actin expression, which coincided with its inhibition of TGF‐β–induced myofibroblast transformation. Our results show that H2S attenuates atrial fibroblast proliferation via suppression of K+ channel activity and moderates their differentiation towards myofibroblasts. 相似文献
994.
黑毛石斛和长距石斛的光合特性 总被引:3,自引:0,他引:3
以黑毛组的黑毛石斛(Dendrobium williamsonii)和长距石斛(D. longicornu)为材料, 对其光合生理特性进行了系统研究。2种石斛叶片的解剖结构为异面叶, 气孔仅分布在下表面, 具气孔盖, 叶脉维管束鞘不含叶绿体, 无花环型结构。2种石斛的光强、CO2浓度和温度的响应研究表明, 它们的光补偿点(LCP)和光饱和点(LSP)分别为5–10 μmol·m−2·s−1和800–900μmol·m−2·s−1,表观量子效率为0.02; CO2补偿点和CO2饱和点分别为80–90 μmol·mol−1和800 μmol·mol−1, 羧化效率在0.015–0.021之间; 光合作用的最适温度为28–30°C。光合特性的研究表明, 2种石斛的净光合速率(Pn)日变化均呈双峰型曲线, 首峰出现在12:00, 最大光合速率为5 μmolCO2·m−2·s−1, 次峰出现在15:00, 夜间不吸收CO2。2种石斛叶片的叶绿素a/叶绿素b比值在2.51–2.66之间。酶活性的测定结果表明, 2种石斛的PEPCase活性极低, 但RuBPCase和GO酶活性较高。以上的研究结果均表明, 黑毛石斛和长距石斛光合作用碳同化途径属C3植物类型, 具有半阴生植物的特点。 相似文献
995.
Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD) in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT), soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC) and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC) and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools. 相似文献
996.
Huanxing Sun Rayman Choo-Wing Angara Sureshbabu Juan Fan Lin Leng Shuang Yu Dianhua Jiang Paul Noble Robert J. Homer Richard Bucala Vineet Bhandari 《PloS one》2013,8(4)
Background
The role and mechanism of action of MIF in hyperoxia-induced acute lung injury (HALI) in the newborn lung are not known. We hypothesized that MIF is a critical regulatory molecule in HALI in the developing lung.Methodology
We studied newborn wild type (WT), MIF knockout (MIFKO), and MIF lung transgenic (MIFTG) mice in room air and hyperoxia exposure for 7 postnatal (PN) days. Lung morphometry was performed and mRNA and protein expression of vascular mediators were analyzed.Results
MIF mRNA and protein expression were significantly increased in WT lungs at PN7 of hyperoxia exposure. The pattern of expression of Angiopoietin 2 protein (in MIFKO>WT>MIFTG) was similar to the mortality pattern (MIFKO>WT>MIFTG) in hyperoxia at PN7. In room air, MIFKO and MIFTG had modest but significant increases in chord length, compared to WT. This was associated with decreased expression of Angiopoietin 1 and Tie 2 proteins in the MIFKO and MIFTG, as compared to the WT control lungs in room air. However, on hyperoxia exposure, while the chord length was increased from their respective room air controls, there were no differences between the 3 genotypes.Conclusion
These data point to the potential roles of Angiopoietins 1, 2 and their receptor Tie2 in the MIF-regulated response in room air and upon hyperoxia exposure in the neonatal lung. 相似文献997.
998.
Li Zhang Ruijing Xiao Jie Xiong Jun Leng Altaf Ehtisham Yi Hu Qianshan Ding Hui Xu Shengwu Liu Jin Wang Dean G. Tang Qiuping Zhang 《PloS one》2013,8(1)
We have previously demonstrated that the CCR9/CCL25 signaling pathway plays an important role in drug resistance in human acute T-lymphocytic leukemia (T-ALL) by inducing activation of ERM protein with polarized distribution in T-ALL cell line MOLT4. However, the mechanism of action of the activated ERM protein in the drug resistance of MOLT4 cells induced by CCL25 remains uncharacterized. Here we investigated the mechanism of CCR9/CCL25-initiated drug resistance in CCR9-high-expressing T-ALL cells. Our results showed that 1) the function of P-gp was increased after treatment with CCL25; 2) P-gp colocalized and co-immunoprecipitated with p-ERM and F-actin in CCL25 treated cells; and 3) ERM-shRNA conferred drug sensitivity coincident with release of ERM interactions with P-gp and F-actin after treatment with CCL25. These data suggest it is pivotal that P-gp associate with the F-actin cytoskeleton through p-ERM in CCR9/CCL25 induced multidrug resistance of T-ALL cells. Strategies aimed at inhibiting P-gp-F-actin cytoskeleton association may be helpful in increasing the efficiency of therapies in T-ALL. 相似文献
999.
1000.
Nana Zhang Maoqiang Zhuang Aixia Ma Guochang Wang Ping Cheng Yajun Yang Xiaofeng Wang Juan Zhang Xingdong Chen Ming Lu 《PloS one》2013,8(12)