Three-dimensional sub-100 nm resolution fluorescence microscopy of thick samples

Imaging volumes as thick as whole cells at three-dimensional (3D) super-resolution is required to reveal unknown features of cellular organization. We report a light microscope that generates images with translationally invariant 30 x 30 x 75 nm resolution over a depth of several micrometers. This method, named biplane (BP) FPALM, combines a double-plane detection scheme with fluorescence photoactivation localization microscopy (FPALM) enabling 3D sub-diffraction resolution without compromising speed or sensitivity.     

Library of electrocatalytic sites in nano-structured domains: electrocatalysis of hydrogen peroxide

Electrochemical detection of hydrogen peroxide at eight types of ormosil-modified electrodes, referred as hexacyanoferrate-system; Prussian blue systems (PB-1, PB-2, and PB-3), palladium (Pd-) system, graphite (Gr-) system, gold nanoparticle (AuNPs) system and palladium-gold nanoparticle (Pd-AuNPs) system were studied. The results on electrochemical detection suggested that hydrogen peroxide does not undergo homogeneous electrochemical mediation; however, the presence of redox mediator within nano-structured domains facilitates the electro-analysis of the same via redox electrocatalysis. Four approaches causing manipulation in nano-structured domains are described: (a) increase in the molecular size of the components generating nano-structured domains; (b) modulation via chemical reactivity; (c) modulation by non-reactive moieties and known nanoparticles; and (d) modulation by mixed approaches (a-c), all leading to decrease in a nano-structured domains. The results demonstrated that an increase in the size of nano-structured domains or decrease in micro-porous geometry increases the efficiency of electrocatalysis. The basic reaction protocol adopted in generating nano-structured domains, followed by manipulation protocols, supported the introduction of a library for creating electrocatalytic sites with varying electrocatalytic efficiency within the same basic nano-structured platform.     

Natural monomeric form of fetal bovine serum acetylcholinesterase lacks the C-terminal tetramerization domain

Acetylcholinesterase isolated from fetal bovine serum (FBS AChE) was previously characterized as a globular tetrameric form. Analysis of purified preparations of FBS AChE by gel permeation chromatography revealed the presence of a stable, catalytically active, monomeric form of this enzyme. The two forms could be distinguished from each other based on their molecular weight, hydrodynamic properties, kinetic properties, thermal stability, and the type of glycans they carry. No differences between the two forms were observed for the binding of classical inhibitors such as edrophonium and propidium or inhibitors that are current or potential drugs for the treatment of Alzheimer's disease such as (-) huperzine A and E2020; tacrine inhibited the monomeric form 2-3-fold more potently than the tetrameric form. Sequencing of peptides obtained from an in-gel tryptic digest of the monomer and tetramer by tandem mass spectrometry indicated that the tetramer consists of 583 amino acid residues corresponding to the mature form of the enzyme, whereas the monomer consists of 543-547 amino acid residues. The subunit molecular weight of the protein component of the monomer (major species) was determined to be 59 414 Da and that of the tetramer as 64 239 Da. The N-terminal of the monomer and the tetramer was Glu, suggesting that the monomer is not a result of truncation at the N-terminal. The only differences detected were at the C-terminus. The tetramer yielded the expected C-terminus, CSDL, whereas the C-terminus of the monomer yielded a mixture of peptides, of which LLSATDTLD was the most abundant. These results suggest that monomeric FBS AChE is trimmed at the C-terminus, and the results are consistent with the involvement of C-terminal amino acids in the assembly of monomers into tetramers.     

温度和光周期影响两种同域发生瓢虫同种和异种组合时的猎物消耗量和利用率（英文）

【目的】印度次大陆是世界上最脆弱的地理景观。气候条件的略微变动可能对其季节周期可能产生不良影响,并引起农业生态系统中蚜虫的大暴发。七星瓢虫Coccinella septempunctata L.和狭臀瓢虫C.transversalis Fab.是该次大陆上广泛分布、同域发生的两种食蚜性瓢虫。【方法】设计异地试验,来探究同种和/或异种组合时的这两种瓢虫用共同的猎物资源(豌豆蚜)饲养时,对增加的温度(15,20,25,30和35℃)和光周期(8L∶16D,12L∶12D和16L∶8D)的响应。【结果】结果表明,在这5个不同温度和3个不同光周期条件下,同种或异种组合时这两种瓢虫表现出了拮抗作用。尽管表现出拮抗作用,但是同种或异种组合的两捕食动物在25℃和长光周期(16L∶8D)条件下消耗、转化和利用的猎物生物量最大。然而,它们的猎物消耗率、转化效率和生长速率在异种组合中最高。在5个不同温度下,4龄幼虫均更有效地利用猎物生物量,将其转变成自身生物量,而雌成虫在3个不同光周期条件下也是如此。【结论】因此可以推断,增加的温度和光周期条件可能不会阻止同种和异种组合中的瓢虫发生拮抗作用,但是在25℃和长光周期(16L∶8D)条件下,相互作用的瓢虫的猎物消耗量和利用率为最佳。     

Mitochondrial DNA Polymerase POLG1 Disease Mutations and Germline Variants Promote Tumorigenic Properties

Germline mutations in mitochondrial DNA polymerase gamma (POLG1) induce mitochondrial DNA (mtDNA) mutations, depletion, and decrease oxidative phosphorylation. Earlier, we identified somatic mutations in POLG1 and the contribution of these mutations in human cancer. However, a role for germline variations in POLG1 in human cancers is unknown. In this study, we examined a role for disease associated germline variants of POLG1, POLG1 gene expression, copy number variation and regulation in human cancers. We analyzed the mutations, expression and copy number variation in POLG1 in several cancer databases and validated the analyses in primary breast tumors and breast cancer cell lines. We discovered 5-aza-2''-deoxycytidine led epigenetic regulation of POLG1, mtDNA-encoded genes and increased mitochondrial respiration. We conducted comprehensive race based bioinformatics analyses of POLG1 gene in more than 33,000 European-Americans and 5,000 African-Americans. We identified a mitochondrial disease causing missense variation in polymerase domain of POLG1 protein at amino acid 1143 (E1143G) to be 25 times more prevalent in European-Americans (allele frequency 0.03777) when compared to African-American (allele frequency 0.00151) population. We identified T251I and P587L missense variations in exonuclease and linker region of POLG1 also to be more prevalent in European-Americans. Expression of these variants increased glucose consumption, decreased ATP production and increased matrigel invasion. Interestingly, conditional expression of these variants revealed that matrigel invasion properties conferred by these germline variants were reversible suggesting a role of epigenetic regulators. Indeed, we identified a set of miRNA whose expression was reversible after variant expression was turned off. Together, our studies demonstrate altered genetic and epigenetic regulation of POLG1 in human cancers and suggest a role for POLG1 germline variants in promoting tumorigenic properties.     

Molecular microbial diversity of a soil sample and detection of ammonia oxidizers from Cape Evans, Mcmurdo Dry Valley, Antarctica

The aim of our study was to estimate the uncultured eubacterial diversity of a soil sample collected below a dead seal, Cape Evans, McMurdo, Antarctica by an SSU rDNA gene library approach. Our study by sequencing of clones from SSU rDNA gene library approach revealed high diversity in the soil sample from Antarctica. More than 50% of clones showed homology to Cytophaga-Flavobacterium-Bacteroides group; sequences also belonged to alpha, beta, gamma proteobacteria, Thermus-Deinococcus and high GC gram-positive group; Phylogenetic analysis of the SSU rDNA clones showed the presence of species belonging to Cytophaga spp., Vitellibacter vladivostokensis, Aequorivita lipolytica, Aequorivita crocea, Flavobacterium spp., Flexibacter sp., Subsaxibacter broadyi, Bacteroidetes, Roseobacter sp., Sphingomonas baekryungensis, Nitrosospira sp., Nitrosomonas cryotolerans, Psychrobacter spp., Chromohalobacter sp., Psychrobacter okhotskensis, Psychrobacter fozii, Psychrobacter urativorans, Rubrobacter radiotolerans, Marinobacter sp., Rubrobacteridae, Desulfotomaculum aeronauticum and Deinococcus sp. The presence of ammonia oxidizing bacteria in Antarctica soil was confirmed by the presence of the amoA gene. Phylogenetic analysis revealed grouping of clones with their respective groups.     

Development of piperazine-tethered heterodimers as potent antimalarials against chloroquine-resistant P. falciparum strains. Synthesis and molecular modeling

The design, synthesis, and antiplasmodial activity of antimalarial heterodimers based on the 1,4-bis(3-aminopropyl)piperazine linker is reported. In this series key structural elements derived from quinoline antimalarials were coupled to fragments capable of coordinating metal ions. Biological evaluation included determination of activity against chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum strains. Some of the novel compounds presented high activity in vitro against chloroquine-resistant strains, more potent than chloroquine and clotrimazole. Computational studies revealed that the activity is likely due to the ability of the compounds to assume a multisite iron coordinating geometry.     

Synthesis and antibacterial activity of 4,5,6,7-tetrahydro-thieno[3,2-c]pyridine quinolones

Synthesis and antibacterial activity of a number of substituted 4,5,6,7-tetrahydro-thieno[3,2-c]pyridine quinolones is reported. The antibacterial activities were evaluated in standard in vitro MIC assay method. Some of the compounds showed in vitro (MIC) antibacterial activity comparable to those of Gatifloxacin, Ciprofloxacin, and Sparfloxacin.     

Effect of hydrophilic polymers on buccoadhesive eudragit patches of propranolol hydrochloride using factorial design

The purpose of this study was to develop formulations and systematically evaluate in vitro performances of buccoadhesive patches of propranolol hydrochloride using the hydrophobic polymer Eudragit L-100 as the base matrix. The hydrophilic polymers Carbopol 934 and polyvinyl pyrrolidone (PVP) K30 were incorporated into the Eudragit patches, to provide the patches with bioadhesive properties and to modify the rate of drug release. The patches, which were prepared by the solvent casting method, were smooth and elegant in appearance; were uniform in thickness, weight, and drug content; showed no visible cracks; and showed good folding endurance. A 3² full factorial design was employed to study the effect of independent variables like hydrophilic polymers Carbopol 934 and PVP K30, which significantly influenced characteristics like swelling index, ex vivo mucoadhesive strength, in vitro drug release, and ex vivo residence time. A stability study of optimized Eudragit patches was done in natural human saliva; it was found that both drug and buccal patches were stable in human saliva. It can be concluded that the present buccal formulation can be an ideal system to improve the bioavailability of the drug by avoiding hepatic first-pass metabolism. Published: June 22, 2007