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991.
A pregnane glycoside fraction from the roots of Asclepias tuberosa L. caused normal human skin fibroblasts to proliferate. This fraction contained 21 pregnane glycosides whose structures were established using NMR spectroscopic analysis and chemical evidence. The aglycones of most of these compounds were identified as 8,12;8,20-diepoxy-8,14-secopregnanes, such as tuberogenin or 5,6-didehydrotuberogenin, the same aglycones as constituents of the aerial parts of this plant. Some of these compounds also caused proliferation of skin fibroblasts. 相似文献
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993.
Unmarked gene deletions facilitate studies of Legionella pneumophila multicomponent processes, such as motility and exonuclease activity. For this purpose, FRT-flanked alleles constructed in Escherichia coli using λ-Red recombinase were transferred to L. pneumophila by natural transformation. Resistance cassettes were then efficiently excised using the Flp site-specific recombinase encoded on a plasmid that is readily lost. 相似文献
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996.
Yoko Kudo-Sakamoto Hiroshi Akazawa Kaoru Ito Jiro Takano Masamichi Yano Chizuru Yabumoto Atsuhiko T. Naito Toru Oka Jong-Kook Lee Yasushi Sakata Jun-ichi Suzuki Takaomi C. Saido Issei Komuro 《The Journal of biological chemistry》2014,289(28):19408-19419
Enzymatic proteolysis by calpains, Ca2+-dependent intracellular cysteine proteases, has been implicated in pathological processes such as cellular degeneration or death. Here, we investigated the role of calpain activation in the hearts subjected to myocardial infarction. We produced myocardial infarction in Cast−/− mice deficient for calpastatin, the specific endogenous inhibitory protein for calpains, and Cast+/+ mice. The activity of cardiac calpains in Cast+/+ mice was not elevated within 1 day but showed a gradual elevation after 7 days following myocardial infarction, which was further pronounced in Cast−/− mice. Although the prevalence of cardiomyocyte death was indistinguishable between Cast−/− and Cast+/+ mice, Cast−/− mice exhibited profound contractile dysfunction and chamber dilatation and showed a significant reduction in survival rate after myocardial infarction as compared with Cast+/+ mice. Notably, immunofluorescence revealed that at 28 days after myocardial infarction, calpains were activated in cardiomyocytes exclusively at the border zone and that Cast−/− mice showed higher intensity and a broader extent of calpain activation at the border zone than Cast+/+ mice. In the border zone of Cast−/− mice, pronounced activation of calpains was associated with a decrease in N-cadherin expression and up-regulation of molecular markers for cardiac hypertrophy and fibrosis. In cultured rat neonatal cardiomyocytes, calpain activation by treatment with ionomycin induced cleavage of N-cadherin and decreased expression levels of β-catenin and connexin 43, which was attenuated by calpain inhibitor. These results thus demonstrate that activation of calpains disassembles cell-cell adhesion at intercalated discs by degrading N-cadherin and thereby promotes left ventricular remodeling after myocardial infarction. 相似文献
997.
Jun Oyanagi Nako Kojima Haruki Sato Shouichi Higashi Keiji Kikuchi Katsuya Sakai Kunio Matsumoto Kaoru Miyazaki 《Experimental cell research》2014
Interaction between tumor cells and stromal fibroblasts plays essential roles in tumor progression. However, its detailed molecular mechanism remains unclear. To understand the mechanism, we investigated molecules mediating this interaction using the three-dimensional (3D) co-culture system of Panc-1 pancreatic carcinoma cells with normal fibroblasts. When the two kinds of cells were placed on the top of collagen gel, the tumor cells scattered into the fibroblast layer, apparently undergoing epithelial‐mesenchymal transition. When fibroblasts were placed within collagen gel, Panc-1 cells actively invaded into the collagen gel, extending a microtubule-based long protrusion. Although transforming growth factor-β (TGF-β) and hepatocyte growth factor (HGF) individually stimulated the tumor cell invasion into collagen gel without fibroblasts, TGF-β signaling inhibitors (SB431542 and LY2157299) significantly enhanced the Panc-1 cell invasion in the 3D co-culture with fibroblasts. Experiments with HGF/Met signaling inhibitors or with the fibroblast conditioned medium revealed that HGF was a major invasion-promoting factor secreted from fibroblasts and SB431542 increased the HGF secretion by blocking the HGF-suppressing activity of cancer cell-derived TGF-β. These results indicate that HGF and TGF-β are critical regulators for both tumor–stroma interaction and tumor invasion. The results also suggest that TGF-β signaling inhibitors may promote tumor progression under some pathological conditions. 相似文献
998.
Ayumi Koike-Takeshita Kaoru Mitsuoka Hideki Taguchi 《The Journal of biological chemistry》2014,289(43):30005-30011
The Escherichia coli chaperonin GroEL is a double-ring chaperone that assists protein folding with the aid of GroES and ATP. Asp-398 in GroEL is known as one of the critical residues on ATP hydrolysis because GroEL(D398A) mutant is deficient in ATP hydrolysis (<2% of the wild type) but not in ATP binding. In the archaeal Group II chaperonin, another aspartate residue, Asp-52 in the corresponding E. coli GroEL, in addition to Asp-398 is also important for ATP hydrolysis. We investigated the role of Asp-52 in GroEL and found that ATPase activity of GroEL(D52A) and GroEL(D52A/D398A) mutants was ∼20% and <0.01% of wild-type GroEL, respectively, indicating that Asp-52 in E. coli GroEL is also involved in the ATP hydrolysis. GroEL(D52A/D398A) formed a symmetric football-shaped GroEL-GroES complex in the presence of ATP, again confirming the importance of the symmetric complex during the GroEL ATPase cycle. Notably, the symmetric complex of GroEL(D52A/D398A) was extremely stable, with a half-time of ∼150 h (∼6 days), providing a good model to characterize the football-shaped complex. 相似文献
999.
Mycorrhizal symbiosis and Lygodium microphyllum Invasion in South Florida—a biogeographic comparison
Pushpa G. Soti Krish Jayachandran Matthew Purcell John C. Volin Kaoru Kitajima 《Symbiosis (Philadelphia, Pa.)》2014,62(2):81-90
Lygodium microphyllum (Old World Climbing Fern) is one of the most problematic weeds in south Florida, invading numerous habitats from mangroves to pine flatwoods natural ecosystems. Much of the research efforts on L. microphyllum has been focused on reproductive potential, spore release, growth under different environmental conditions, belowground rhizome dormancy and survival strategies that describes its invasiveness. However, the role of an important mutualistic association with arbuscular mycorrhizal fungi (AMF) in the competitive ability and successful invasion of L. microphyllum by enhancing nutrient uptake has not been previously considered. Analysis of field root and soil samples from the ferns introduced and native range as well as a 7-week growth chamber experiment were done to determine the level of mycorrhizal colonization in the roots of L. microphyllum and the dependency on mycorrhizal fungi for growth and phosphorus (P) uptake. The field root samples showed that L. microphyllum was heavily colonized by AMF in relatively drier conditions, which are commonly found on some Florida sites compared to more common wetter sites where the fern is found in its native Australia. The results from the growth chamber experiment showed that the mycorrhizal treatment plants had significantly higher relative growth rate and biomass compared to the non-mycorrhizal plants. Similarly, L. microphyllum was highly dependent on the mycorrhizal fungi for growth and P uptake. Our results suggest that AMF play a significant role in vegetative reproduction and likely enhance the invasiveness of L. microphyllum in south Florida natural areas. 相似文献
1000.
Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012 总被引:1,自引:0,他引:1
Yoshihiro Ohmori Yayoi Inui Masataka Kajikawa Atsumi Nakata Naoyuki Sotta Koji Kasai Shimpei Uraguchi Nobuhiro Tanaka Sho Nishida Takahiro Hasegawa Takuya Sakamoto Yuko Kawara Kayoko Aizawa Haruka Fujita Ke Li Naoya Sawaki Koshiro Oda Ryuichiro Futagoishi Takahiro Tsusaka Satomi Takahashi Junpei Takano Shinji Wakuta Akira Yoshinari Masataka Uehara Shigeki Takada Hayato Nagano Kyoko Miwa Izumi Aibara Takuya Ojima Kaoru Ebana Satoru Ishikawa Kuni Sueyoshi Hiroshi Hasegawa Tetsuro Mimura Mari Mimura Natsuko I. Kobayashi Jun Furukawa Daisuke Kobayashi Toshiyasu Okouchi Keitaro Tanoi Toru Fujiwara 《Journal of plant research》2014,127(1):57-66
After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice. 相似文献