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991.
In a survey of endophytic fungi associated with medicinal plants, two species of the genus Sporormiella Ellis & Everh. were isolated in 2005. So far only one species S. minimoides was reported in China (Wang & Guo, 2004). The two species are found to be new records in China, and they are redescribed and illustrated herein. 相似文献
992.
LU Aiping LI Qing LIU Jingwen . Department of Pathology Peking University School of Oncology Beijing Cancer Hospital Beijing China . VA Palo alto Health Care System Palo Alto California CA USA 《中国科学:生命科学英文版》2006,49(4):403-408
Breast cancer specific gene 1, also referred as synu-clein γ, was originally isolated from a human breasttumor cDNA library[1]. It reveals extensive sequencehomology to a family of neuronal cytosolic proteins,synuclein α and synuclein β[2,3]. Synuclein… 相似文献
993.
Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003 总被引:16,自引:0,他引:16
Alexander C Andersson HS Andersson LI Ansell RJ Kirsch N Nicholls IA O'Mahony J Whitcombe MJ 《Journal of molecular recognition : JMR》2006,19(2):106-180
Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented. 相似文献
994.
995.
Approximately 60,000 microorganisms from Saskatchewan soil were screened for growth on the cytokinin N6-benzyladenine (BA) as C source. A single isolate, identified as Serratia proteamaculans, grew well on BA. The culture filtrates from S. proteamaculans were screened using reversed phase high performance liquid chromatography (RP-HPLC) for the presence of secondary metabolites. The analysis revealed a major metabolite and its chemical structure was deduced as 8-hydroxy-N6-benzyladenine (8-OHBA). Subsequently, the S. proteamaculans isolate was also found to metabolize N6-(2-isopentenyl)adenine and adenine through oxidation of C-8 of the purine ring. A clone of the S. proteamaculans xanthine dehydrogenase (Xdh, EC 1.1.1.204) encoding genes was isolated in Escherichia coli. This E. coli isolate metabolized BA to 8-OHBA. Similar to other bacterial Xdh, the S. proteamaculans enzyme was composed of two subunits. The derived amino acid sequences of these Xdh subunits were most similar (XdhA, 60%; XdhB, 72%) to those of Pseudomonas aeruginosa. 相似文献
996.
DI Osolodkin LI Kozlovskaya VA Palyulin VM Pentkovski GG Karganova NS Zefirov 《Biochemical and biophysical research communications》2012,423(2):207-211
Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca(2+) oscillation in pancreatic β-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca(2+) oscillation we designed and conducted experiments in intact primary pancreatic β-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic β-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca(2+) indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca(2+) oscillation. The pattern of glucose-induced Ca(2+) oscillation in the nucleus and cytosol was similar. The reduction of Ca(2+) oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca(2+) amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic β-cells. 相似文献
997.
Tauopathies are characterized by abnormal aggregation of the microtubule associated protein tau. This aggregation is thought to occur when tau undergoes shifts from its native conformation to one that exposes hydrophobic areas on separate monomers, allowing contact and subsequent association into oligomers and filaments. Molecular chaperones normally function by binding to exposed hydrophobic stretches on proteins and assisting in their refolding. Chaperones of the heat shock protein 70 (Hsp70) family have been implicated in the prevention of abnormal tau aggregation in adult neurons. Tau exists as six alternatively spliced isoforms, and all six isoforms appear capable of forming the pathological aggregates seen in Alzheimer's disease. Because tau isoforms differ in primary sequence, we sought to determine whether Hsp70 would differentially affect the aggregation and microtubule assembly characteristics of the various tau isoforms. We found that Hsp70 inhibits tau aggregation directly and not through inducer-mediated effects. We also determined that Hsp70 inhibits the aggregation of each individual tau isoform and was more effective at inhibiting the three repeat isoforms. Finally, all tau isoforms robustly induced microtubule formation while in the presence of Hsp70. The results presented herein indicate that Hsp70 affects tau isoform dysfunction while having very little impact on the normal function of tau to mediate microtubule assembly. This indicates that targeting Hsp70 to tau may provide a therapeutic approach for the treatment of tauopathies that avoids disruption of normal tau function. 相似文献
998.
Lezcano V Bellido T Plotkin LI Boland R Morelli S 《Archives of biochemistry and biophysics》2012,518(2):95-102
Bisphosphonates (BPs) inhibit osteocyte and osteoblast apoptosis via opening of connexin (Cx) 43 hemichannels and activating the extracellular signal regulated kinases ERKs. Previously, we hypothesized that intracellular survival signaling is initiated by interaction of BPs with Cx43. However, using whole cell binding assays with [(3)H]-alendronate, herein we demonstrated the presence of saturable, specific and high affinity binding sites in the Cx43-expressing ROS 17/2.8 osteoblastic cells, authentic osteoblasts and MLO-Y4 cells expressing Cx43 or not, as well as in HeLa cells lacking Cx43 expression and ROS 17/2.8 cells pretreated with agents that disassemble Cx channels. In addition, both BPs and the PTP inhibitor Na(3)VO(4) increased proliferation of cells expressing Cx43 or not. Furthermore, although BPs are internalized and inhibit intracellular enzymes in osteoclasts, whether the drugs penetrate non-resorptive bone cells is not known. To clarify this, we evaluated the osteoblastic uptake of AF-ALN, a fluorescently labeled analog of alendronate. AF-ALN was rapidly internalized in cells expressing Cx43 or not indicating that this process is not mediated via Cx43 hemichannels. Altogether, these findings suggest that although required for triggering intracellular survival signaling by BPs, Cx43 is dispensable for cellular BP binding, its uptake, as well as the proliferative effects of these agents. 相似文献
999.
The wheat seedling endonucleases WEN1 and WEN2 dependent on Mg2+, Ca2+, and S-adenosyl-L-methionine (SAM) and sensitive to the substrate DNA methylation status have an expressed processing action. The enzymes hydrolyze
DNA at a few subsequent stages: first, they split λ phage DNA specifically at CNG-sites (WEN1) with liberation of large fragments;
second, they hydrolyze these fragments to 120–140 bp oligonucleotides that finally are hydrolyzed to very short fragments
and mononucleotides. Initial stages of DNA hydrolysis may proceed in the absence of Mg2+, but subsequent hydrolysis stages are very strongly stimulated by Mg2+. It cannot be ruled out that modulation of enzymatic activity with Mg2+ and probably with DNA fragments formed is associated with reorganization of the structure of eukaryotic (wheat) endonucleases
with respective changes in their catalytic properties and site specificity of action. Michaelis constant value for WEN1 endonuclease
on hydrolysis of methylated λ phage DNA containing Cm5CWGG and Gm6ATC sites is four-fold lower compared with that observed on hydrolysis of unmethylated λ phage DNA. This may indicate that
affinity of WEN1 enzyme to methylated DNA is higher than that to unmethylated DNA. In the presence of SAM, the Michaelis constant
for WEN2 on the DNA hydrolysis stage characterized by formation of 120–140 bp fragments is decreased, but for WEN1 it is increased
by 1.5–2.0-fold. This means that SAM inhibits WEN1 but stimulates WEN2. Thus, wheat endonucleases WEN1 and WEN2 differ significantly
in affinities to substrate DNAs with different methylation status, in velocities of DNA hydrolysis, and time of production
of DNA fragments of similar length. It seems that the investigated plant endonucleases can hydrolyze DNA in the nucleus as
well to both large and very short fragments including mononucleotides, that is, in particular, essential for utilization of
cell nucleic acid material during apoptosis. 相似文献
1000.
Hüttemann M Helling S Sanderson TH Sinkler C Samavati L Mahapatra G Varughese A Lu G Liu J Ramzan R Vogt S Grossman LI Doan JW Marcus K Lee I 《Biochimica et biophysica acta》2012,1817(4):598-609
Cytochrome c (Cytc) and cytochrome c oxidase (COX) catalyze the terminal reaction of the mitochondrial electron transport chain (ETC), the reduction of oxygen to water. This irreversible step is highly regulated, as indicated by the presence of tissue-specific and developmentally expressed isoforms, allosteric regulation, and reversible phosphorylations, which are found in both Cytc and COX. The crucial role of the ETC in health and disease is obvious since it, together with ATP synthase, provides the vast majority of cellular energy, which drives all cellular processes. However, under conditions of stress, the ETC generates reactive oxygen species (ROS), which cause cell damage and trigger death processes. We here discuss current knowledge of the regulation of Cytc and COX with a focus on cell signaling pathways, including cAMP/protein kinase A and tyrosine kinase signaling. Based on the crystal structures we highlight all identified phosphorylation sites on Cytc and COX, and we present a new phosphorylation site, Ser126 on COX subunit II. We conclude with a model that links cell signaling with the phosphorylation state of Cytc and COX. This in turn regulates their enzymatic activities, the mitochondrial membrane potential, and the production of ATP and ROS. Our model is discussed through two distinct human pathologies, acute inflammation as seen in sepsis, where phosphorylation leads to strong COX inhibition followed by energy depletion, and ischemia/reperfusion injury, where hyperactive ETC complexes generate pathologically high mitochondrial membrane potentials, leading to excessive ROS production. Although operating at opposite poles of the ETC activity spectrum, both conditions can lead to cell death through energy deprivation or ROS-triggered apoptosis. 相似文献