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Find video protocols related to scientific articles indexed in Pubmed.
Directional properties of fluorenylidene moieties in unsymmetrically substituted N-heterocyclic carbenes. Unexpected CH activation of a methylfluorenyl group with palladium. Use in palladium catalysed Suzuki-Miyaura cross coupling of aryl chlorides.
Dalton Trans
PUBLISHED: 06-14-2014
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Benzimidazolium salts having their two nitrogen atoms substituted by different 9-alkylfluorenyl groups ( and , alkyl(1)/alkyl(2) = Me/Et, Me/Pr, Me/n-Bu, Me/i-Pr, Me/Bn, Me/CH2SMe have been synthesised in high yields in two or three steps from N,N'-bis(9H-fluoren-9-ylidene)benzene-1,2-diamine (). The imidazolium salts were converted readily into the corresponding PEPPSI-type palladium complexes (PEPPSI = pyridine-enhanced precatalyst preparation stabilisation and initiation), while reaction of the methylthioether-substituted salt with PdCl2/K2CO3/pyridine afforded the palladacycle resulting from metallation of the methyl group attached to the fluorenylidene moiety. NMR and X-ray diffraction studies revealed that the carbene ligands in behave as clamp-like ligands, the resulting metal confinement arising from a combination of the orientational properties of the fluorenylidene moieties that push the alkyl groups towards the metal centre and attractive anagostic interactions involving CH2(fluorenyl) groups. Complexes were assessed in Suzuki-Miyaura cross-coupling reactions. Like their symmetrical analogues they displayed high activity in the coupling of phenyl boronic acid with p-tolylchloride but their performance remained slightly inferior to that of the related, symmetrical Et/Et complex .
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Origin of a novel regulatory module by duplication and degeneration of an ancient plant transcription factor.
Mol. Phylogenet. Evol.
PUBLISHED: 04-04-2014
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It is commonly believed that gene duplications provide the raw material for morphological evolution. Both the number of genes and size of gene families have increased during the diversification of land plants. Several small proteins that regulate transcription factors have recently been identified in plants, including the LITTLE ZIPPER (ZPR) proteins. ZPRs are post-translational negative regulators, via heterodimerization, of class III Homeodomain Leucine Zipper (C3HDZ) proteins that play a key role in directing plant form and growth. We show that ZPR genes originated as a duplication of a C3HDZ transcription factor paralog in the common ancestor of euphyllophytes (ferns and seed plants). The ZPRs evolved by degenerative mutations resulting in loss all of the C3HDZ functional domains, except the leucine zipper that modulates dimerization. ZPRs represent a novel regulatory module of the C3HDZ network unique to the euphyllophyte lineage, and their origin correlates to a period of rapid morphological changes and increased complexity in land plants. The origin of the ZPRs illustrates the significance of gene duplications in creating developmental complexity during land plant evolution that likely led to morphological evolution.
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An undergraduate study of two transcription factors that promote lateral root formation.
Biochem Mol Biol Educ
PUBLISHED: 01-06-2014
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We present a lab that enables students to test the role of genes involved in the regulation of lateral roots growth in the model plant Arabidopsis thaliana. Here, students design an experiment that follows the effects of the hormone auxin on the stimulation of genes involved in the formation of lateral root initials. These genes, known as lateral organ boundary domain containing protein (LBD) genes, are upregulated in the presence of auxin as part of a multistep molecular and biochemically controlled pathway. Depending on which LBD gene is tested, and the stage of root development, expression patterns are localized in a discrete and punctate fashion at the site of lateral root initials (LBD33), or reveal a broader localization pattern (LBD16). Students view expression using the reporter gene GUS (beta-glucuronidase). Before GUS staining, students view root growth in a "pseudo-aseptic" agar-based environment that allows complete visualization of whole root development to determine the proper stage to test molecular expression.
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Genetic analysis of resistance to six virus diseases in a multiple virus-resistant maize inbred line.
Theor. Appl. Genet.
PUBLISHED: 01-03-2014
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Novel and previously known resistance loci for six phylogenetically diverse viruses were tightly clustered on chromosomes 2, 3, 6 and 10 in the multiply virus-resistant maize inbred line, Oh1VI. Virus diseases in maize can cause severe yield reductions that threaten crop production and food supplies in some regions of the world. Genetic resistance to different viruses has been characterized in maize populations in diverse environments using different screening techniques, and resistance loci have been mapped to all maize chromosomes. The maize inbred line, Oh1VI, is resistant to at least ten viruses, including viruses in five different families. To determine the genes and inheritance mechanisms responsible for the multiple virus resistance in this line, F1 hybrids, F2 progeny and a recombinant inbred line (RIL) population derived from a cross of Oh1VI and the virus-susceptible inbred line Oh28 were evaluated. Progeny were screened for their responses to Maize dwarf mosaic virus, Sugarcane mosaic virus, Wheat streak mosaic virus, Maize chlorotic dwarf virus, Maize fine streak virus, and Maize mosaic virus. Depending on the virus, dominant, recessive, or additive gene effects were responsible for the resistance observed in F1 plants. One to three gene models explained the observed segregation of resistance in the F2 generation for all six viruses. Composite interval mapping in the RIL population identified 17 resistance QTLs associated with the six viruses. Of these, 15 were clustered in specific regions of chr. 2, 3, 6, and 10. It is unknown whether these QTL clusters contain single or multiple virus resistance genes, but the coupling phase linkage of genes conferring resistance to multiple virus diseases in this population could facilitate breeding efforts to develop multi-virus resistant crops.
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Calix[4]arenes with one and two N-linked imidazolium units as precursors of N-heterocyclic carbene complexes. Coordination chemistry and use in Suzuki-Miyaura cross-coupling.
Dalton Trans
PUBLISHED: 08-30-2011
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The calix[4]arene-imidazolium salts 5-(3-butyl-1-imidazolylium)-25,26,27,28-tetrabenzyloxy-calix[4]arene bromide (cone) (2), and 5,11-bis(3-alkyl-1-imidazolylium)-25,26,27,28-tetrabenzyloxycalix[4]arene diiodide (cone) (R = methyl, 3a; R = n-butyl, 3b) have been synthesised. Reaction of 2 in dioxane with PdCl(2) in the presence of CsCO(3) and KBr (80 °C, 24 h) gives the carbene complex trans-[PdBr(2)(calix-monocarbene)(2)] (14), containing two N-heterocyclic carbene ligands derived from 2 (yield: 63%). Repeating the reaction in pyridine instead of dioxane gives the mixed pyridine-carbene complex trans-[PdBr(2)(calix-carbene)(pyridine)] (15) in 75% yield. Treatment of the bis-imidazolium salt 3a with [Pd(OAc)(2)] affords a chelate complex, trans-[PdI(2){calix-bis(carbene)}] (16), in which a metallo-(bis-carbene) fragment caps the upper rim of the calixarene basket. Complex 16, as well as its analogue 17, obtained from 3b, display apparent C(s)-symmetry in solution. This is not the case in the solid state, a single X-ray diffraction study carried out for 16 revealing a pinced cone structure for the calixarene skeleton, which reduces the symmetry to C(1). The chelate complex 17 shows poor activity in Suzuki-Miyaura cross-coupling of phenyl boronic acid and p-tolyl halides, an observation that suggests the presence of a strained metallocyclic unit preventing easy stereochemical rearrangement to an active species. Unlike 17, complexes 14 and 15 show good activities in cross-coupling. A comparative study using the carbene precursor 1-butyl-3-(2,6-diisopropylphenyl)imidazolium bromide (18), which is devoid of the receptor fragment, strongly suggests that the carbene ligands of 14 and 15 operate typically as bulky NHC-ligands.
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The impact of outgroup choice and missing data on major seed plant phylogenetics using genome-wide EST data.
PLoS ONE
PUBLISHED: 04-16-2009
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Genome level analyses have enhanced our view of phylogenetics in many areas of the tree of life. With the production of whole genome DNA sequences of hundreds of organisms and large-scale EST databases a large number of candidate genes for inclusion into phylogenetic analysis have become available. In this work, we exploit the burgeoning genomic data being generated for plant genomes to address one of the more important plant phylogenetic questions concerning the hierarchical relationships of the several major seed plant lineages (angiosperms, Cycadales, Gingkoales, Gnetales, and Coniferales), which continues to be a work in progress, despite numerous studies using single, few or several genes and morphology datasets. Although most recent studies support the notion that gymnosperms and angiosperms are monophyletic and sister groups, they differ on the topological arrangements within each major group.
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A mutation in the Proteosomal Regulatory Particle AAA-ATPase-3 in Arabidopsis impairs the light-specific hypocotyl elongation response elicited by a glutamate receptor agonist, BMAA.
Plant Mol. Biol.
PUBLISHED: 02-10-2009
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BMAA is a cycad-derived glutamate receptor agonist that causes a two- to three-fold increase in hypocotyl elongation on Arabidopsis seedlings grown in the light. To probe the role of plant glutamate receptors and their downstream mediators, we utilized a previously described genetic screen to identify a novel, BMAA insensitive morphology (bim) mutant, bim409. The normal BMAA-induced hypocotyl elongation response observed on wild-type seedlings grown in the light is impaired in the bim409 mutant. This BMAA-induced phenotype is light-specific, as the bim409 mutant exhibits normal hypocotyl elongation in etiolated (dark grown) plants (+ or - BMAA). The mutation in bim409 was identified to be in a gene encoding the Proteosomal Regulatory Particle AAA-ATPase-3 (RPT3). Possible roles of the proteosome in Glu-mediated signaling in plants is discussed.
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Kinetic modeling and occupancy measures of the norepinephrine transporters in baboons using single photon emission computed tomography with (123)I-INER.
Synapse
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This study aims to investigate the pharmacokinetics of a recently developed radiotracer for imaging of the norepinephrine transporter (NET) in baboon brain, (123)I-INER, using single photon emission computed tomography (SPECT). In addition, it also aims to determine NET occupancy by atomoxetine and reboxetine, two selective norepinephrine reuptake inhibitors, using (123)I-INER in baboons. Baseline and preblocking studies with a high dose of atomoxetine (0.85 mg/kg) were conducted in three baboons using SPECT with (123)I-INER administered as a bolus. Kinetic modeling analysis was investigated for different models, namely invasive and reference tissue models. Bolus plus constant infusion experiments with displacement at equilibrium using six different doses of atomoxetine (0.03-0.85 mg/kg) and four different doses of reboxetine (0.5-3.0 mg/kg) were carried out in several baboons to obtain occupancy measurements as a function of dose for the two NET selective drugs. Results showed that reference tissue models can be used to estimate binding potential values and occupancy measures of (123)I-INER in different brain regions. In addition, the apparent volume of distribution was estimated by dividing concentration in tissue by the concentration in blood at 3 hours postinjection. After administration of atomoxetine or reboxetine, a dose-dependent occupancy was observed in brain regions known to contain high densities of NET. In conclusion, pharmacokinetic properties of (123) I-INER were successfully described, and obtained results may be used to simplify future data acquisition and image processing. Dose-dependent NET occupancy for two selective norepinephrine reuptake inhibitors was successfully measured in vivo in baboon brain using SPECT and (123) I-INER.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.