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91.
Uhram Song Minjoo Shin Gisuk Lee Jinkyu Roh Younghun Kim Eun Ju Lee 《Biological trace element research》2013,155(1):93-103
Titanium dioxide nanoparticles (nano-TiO2) are manufactured and used worldwide in large quantities. However, phytotoxicity research on nano-TiO2 has yielded confusing results, ranging from strong toxicity to positive effects. Therefore, in this research, the effects of nano-TiO2 on the germination and root elongation of seed and seedlings were studied. Additionally, the uptake and physiological responses of mature plants were investigated. Physical chemistry data were analyzed to assess the availability of nano-TiO2. Finally, a hydroponic system designed to overcome nano-TiO2 precipitation was used to reproduce the environmental conditions of actual fields. Nano-TiO2 did not have any effect on seed germination or on most of the plant species tested. Nano-TiO2 had positive effects on root elongation in some species. No physiological differences in enzyme activities or chlorophyll content were detected, even though the plants absorbed nano-TiO2. Physical chemistry data showed that nano-TiO2 agglomerated rapidly and formed particles with much bigger hydrodynamic diameters, even in distilled water and especially in a hydroponic system. Furthermore, agglomerated nano-TiO2 formed precipitates; this would be more severe in an actual field. Consequently, nano-TiO2 would not be also readily available to plants and would not cause any significant effects on plants. Our results and other reports suggest that titanium itself is not phytotoxic, even though plants absorb titanium. In conclusion, nano-TiO2 is not toxic to the three plant species, in vitro or in situ. 相似文献
92.
Davide Randazzo Emiliana Giacomello Stefania Lorenzini Daniela Rossi Enrico Pierantozzi Bert Blaauw Carlo Reggiani Stephan Lange Angela K. Peter Ju Chen Vincenzo Sorrentino 《The Journal of cell biology》2013,200(4):523-536
Obscurin is a large myofibrillar protein that contains several interacting modules, one of which mediates binding to muscle-specific ankyrins. Interaction between obscurin and the muscle-specific ankyrin sAnk1.5 regulates the organization of the sarcoplasmic reticulum in striated muscles. Additional muscle-specific ankyrin isoforms, ankB and ankG, are localized at the subsarcolemma level, at which they contribute to the organization of dystrophin and β-dystroglycan at costameres. In this paper, we report that in mice deficient for obscurin, ankB was displaced from its localization at the M band, whereas localization of ankG at the Z disk was not affected. In obscurin KO mice, localization at costameres of dystrophin, but not of β-dystroglycan, was altered, and the subsarcolemma microtubule cytoskeleton was disrupted. In addition, these mutant mice displayed marked sarcolemmal fragility and reduced muscle exercise tolerance. Altogether, the results support a model in which obscurin, by targeting ankB at the M band, contributes to the organization of subsarcolemma microtubules, localization of dystrophin at costameres, and maintenance of sarcolemmal integrity. 相似文献
93.
JAK2 mediates the acute response to decreased cell volume in mouse preimplantation embryos by activating NHE1 总被引:1,自引:0,他引:1
Preimplantation mouse embryos are particularly sensitive to increased osmolarity within their normal physiological range. The detrimental effects can be alleviated by organic osmolytes such as glycine transported into early embryos, an effect thought to be due to the organic osmolyte replacing a portion of intracellular inorganic ions accumulated during acute cell volume regulation. However, no mechanism of cell volume regulation dependent on inorganic ions has been identified in preimplantation embryos. We found that decreased cell volume rapidly activated Na+/H+ exchange in preimplantation mouse embryos. This activity was likely mediated by the NHE1 (Slc9a1) isoform, since it was blocked by the highly selective NHE1 inhibitor, cariporide, which also inhibited the ability of the 1‐cell embryo to maintain cell volume. How NHE1 is activated by decreased cell volume is not generally well understood. Full activation of NHE1 by decreased cell volume in 2‐cell mouse embryos required the activity of the tyrosine kinase Janus kinase 2 (Jak2), since NHE1 activation was inhibited by the general tyrosine kinase inhibitor genistein, several selective inhibitors of Jak2, and dominant negative Jak2 expressed in 2‐cell embryos. Decreased cell volume furthermore resulted in increased tyrosine phosphorylation of proteins in 2‐cell embryos detected both by anti‐phosphotyrosine antibody and an antibody directed against active phospho‐Jak2. Thus, Jak2 apparently serves as a cell volume sensor in embryos. Evidence from pharmacological inhibitors further indicated that NHE1 activation by decreased cell volume was dependent on calmodulin activity, likely downstream of Jak2, and required active phospholipase C. J. Cell. Physiol. 228: 428–438, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
94.
95.
Ju Chu Jiangchao Qian Yingping Zhuang Siliang Zhang Yourong Li 《Applied microbiology and biotechnology》2013,97(1):41-49
This minireview mainly aims at the study of S-adenosyl-l-methionine (SAM) production by microbial fermentation. A brief introduction of the biological role and application of SAM was presented. In general, SAM production can be improved by breeding of the producing strain through the conventional mutation or genetic engineering approach in the molecular or cellular scale, by optimization of culture conditions in the cellular scale or bioreactor engineering scale, or by multiscale approach. The productivity of SAM fermentation has been improved greatly through the efforts of many researchers using the methods previously mentioned. The SAM-producing strains used extensively are Pichia pastoris and Saccharomyces cerevisiae. The effect of SAM on antibiotic production was also exemplified. The skill and scheme beneficial to the improvement of SAM production involves the enhancement of SAM synthetase (methionine adenosyltransferase) activity and selection of engineered constitutive promoters with appropriate strength; seeking for and eliminating the rate-limiting factors in SAM synthesis, namely, knocking off the genes that transform SAM and l-methionine (L-Met) to cysteine; release the feedback inhibition of SAM to methylenetetrahydrofolate reductase; blocking the transsulfuration pathway by interfering the responsible enzymes; enhancing ATP level through pulsed feeding of glycerol; and optimizing the L-Met feeding strategy. Precise control of gene expression and quantitative assessment of physiological parameters in engineered P. pastoris were highlighted. Finally, a discussion of the prospect of SAM production was presented. 相似文献
96.
Xunlong Shi Zhihui Shi Hai Huang Hongguang Zhu Haiyan Zhu Dianwen Ju Pei Zhou 《Applied microbiology and biotechnology》2013,97(23):10025-10033
Therapeutic recombinant human catalase (rhCAT) can quench infection-induced reactive oxygen species (ROS), thereby alleviating the associated tissue damage. Although the intranasal route is efficient to deliver native rhCAT to the lung, the therapeutic effect is limited by rapid elimination from the blood. In this study, we modified rhCAT with the active polymer, polyethylene glycol monomethyl ether (PEG)-5000, and analyzed the pharmacokinetics of PEGylated rhCAT in mice. The high tetra-PEGylation ratio was about 60 %, and PEGylation prolonged the half-life of rhCAT in serum (75 vs. 13.5 min for native rhCAT). The protective effects of PEG-rhCAT were investigated in a mouse model of influenza virus A (H1N1)-associated pneumonia. PEG-rhCAT was more effectively delivered than native rhCAT and was associated with higher survival ratio, less extensive lung injuries, reduced ROS levels, and lower viral replication. Collectively, these findings indicate that PEGylation can enhance the therapeutic efficacy of native rhCAT and suggest that PEGylated rhCAT may represent a novel complement therapy for H1N1 influenza-induced pneumonia. 相似文献
97.
98.
A. Juárez‐Escario J. Valls X.O. Solé‐Senan J.A. Conesa 《The Annals of applied biology》2013,162(2):200-213
In addition to their impact on natural habitats, invasive alien plants can have a significant negative effect on agricultural systems and cause economic losses. Flood‐irrigated orchards in the Mediterranean Basin are vulnerable to the invasion of alien weeds, primarily because of the traditional management practices used in the orchards, which are characterized by high soil moisture during the dry summer period, nutrient availability and high levels of disturbance. This study sought to determine whether their biological traits can explain the success of alien weed species. To answer this question, 408 floristic relevés were conducted in 136 flood‐irrigated orchards on the Plains of Lleida (Catalonia, NE of Spain). Richness and cover of native and alien weeds were compared. Furthermore, a set of biological traits were compared between successful and non‐successful weeds for the whole data and separately between native and alien weeds using logistic regression and classification trees. In flood‐irrigated orchards, alien species covered most of their area, even though the richness of alien species was lower than that of the native species. The most important species were C4 species with seeds dispersed by water, and on the other hand, rosulate and caespitose‐reptant hemicryptophytes with long flowering period. Most of these traits fitted with those of the invasive alien weeds, which were mostly C4 species with seeds dispersed by water. Perennial life form characterized successful native weeds. In this study, we discuss how the traditional management of flood irrigation in fruit‐tree orchards favours invasive alien weeds that have specific traits, acting as a reservoir for the spread of alien weeds into other crops and surrounding riparian habitats. We also propose changing management practices in order to avoid the selection of alien weeds and to promote native species. 相似文献
99.
Kyong-Cheol Ko Ju Hee LeeJong Hyun Choi Jae Jun Song 《Biochemical and biophysical research communications》2013
Metagenomic resources representing ruminal bacteria were screened for novel exocellulases using a robotic, high-throughput screening system, the novel CelEx-BR12 gene was identified and the predicted CelEx-BR12 protein was characterized. The CelEx-BR12 gene had an open reading frame (ORF) of 1140 base pairs that encoded a 380-amino-acid-protein with a predicted molecular mass of 41.8 kDa. The amino acid sequence was 83% identical to that of a family 5 glycosyl hydrolase from Prevotella ruminicola 23. Codon-optimized CelEx-BR12 was overexpressed in Escherichia coli and purified using Ni–NTA affinity chromatography. The Michaelis–Menten constant (Km value) and maximal reaction velocity (Vmax values) for exocellulase activity were 12.92 μM and 1.55 × 10−4 μmol min−1, respectively, and the enzyme was optimally active at pH 5.0 and 37 °C. Multifunctional activities were observed against fluorogenic and natural glycosides, such as 4-methylumbelliferyl-β-d-cellobioside (0.3 U mg−1), CMC (105.9 U mg−1), birch wood xylan (132.3 U mg−1), oat spelt xylan (67.9 U mg−1), and 2-hydroxyethyl-cellulose (26.3 U mg−1). Based on these findings, we believe that CelEx-BR12 is an efficient multifunctional enzyme as endocellulase/exocellulase/xylanase activities that may prove useful for biotechnological applications. 相似文献
100.
Kishan?Kumar Chudasama Jonathon Winnay Stefan Johansson Tor Claudi Rainer K?nig Ingfrid Haldorsen Bente Johansson Ju?Rang Woo Dagfinn Aarskog J?rn?V. Sagen C.?Ronald Kahn Anders Molven P?l?Rasmus Nj?lstad 《American journal of human genetics》2013,93(1):150-157
The phosphatidylinositol 3 kinase (PI3K) pathway regulates fundamental cellular processes such as metabolism, proliferation, and survival. A central component in this pathway is the p85α regulatory subunit, encoded by PIK3R1. Using whole-exome sequencing, we identified a heterozygous PIK3R1 mutation (c.1945C>T [p.Arg649Trp]) in two unrelated families affected by partial lipodystrophy, low body mass index, short stature, progeroid face, and Rieger anomaly (SHORT syndrome). This mutation led to impaired interaction between p85α and IRS-1 and reduced AKT-mediated insulin signaling in fibroblasts from affected subjects and in reconstituted Pik3r1-knockout preadipocytes. Normal PI3K activity is critical for adipose differentiation and insulin signaling; the mutated PIK3R1 therefore provides a unique link among lipodystrophy, growth, and insulin signaling. 相似文献