22 research outputs found
Room-Temperature, Copper-Free Sonogashira Reactions Facilitated by Air-Stable, Monoligated Precatalyst [DTBNpP] Pd(crotyl)Cl
A novel application of [DTBNpP] PdÂ(crotyl)ÂCl
(DTBNpP = di-tert-butylneopentylphosphine) (P2), an air-stable,
commercially available palladium precatalyst that allows rapid access
to a monoligated state, has been identified for room-temperature,
copper-free Sonogashira couplings of challenging aryl bromides and
alkynes. The mild reaction conditions with TMP in dimethyl sulfoxide
afford up to 97% yields, excellent functional group tolerability,
and broad reaction compatibility with access to one-pot indole formation
Neural mechanism of spatio-chromatic opponency in the Drosophila amacrine neurons
Visual animals detect spatial variations of light intensity and wavelength composition. Opponent coding is a common strategy for reducing information redundancy. Neurons equipped with both spatial and spectral opponency have been identified in vertebrates but not yet in insects. The Drosophila amacrine neuron Dm8 was recently reported to show color opponency. Here, we demonstrate Dm8 exhibits spatio-chromatic opponency. Antagonistic convergence of the direct input from the UV-sensing R7s and indirect input from the broadband receptors R1-R6 through Tm3 and Mi1 is sufficient to confer Dm8's UV/Vis (ultraviolet/visible light) opponency. Using high resolution monochromatic stimuli, we show the pale and yellow subtypes of Dm8s, inheriting retinal mosaic characteristics, have distinct spectral tuning properties. Using 2D white-noise stimulus and reverse correlation analysis, we found that the UV receptive field (RF) of Dm8 has a center-inhibition/surround-excitation structure. In the absence of UV-sensing R7 inputs, the polarity of the RF is inverted owing to the excitatory input from the broadband photoreceptors R1-R6. Using a new synGRASP method based on endogenous neurotransmitter receptors, we show that neighboring Dm8s form mutual inhibitory connections mediated by the glutamate-gated chloride channel GluCla, which is essential for both Dm8's spatial opponency and animals' phototactic behavior. Our study shows spatio-chromatic opponency could arise in the early visual stage, suggesting a common information processing strategy in both invertebrates and vertebrates
SCORHE:A System for Automated Video-Based Assessment of Activity and Behavior for Mice Housed in a Home-Cage Environment
SCORHE:A System for Automated Video-Based Assessment of Activity and Behavior for Mice Housed in a Home-Cage Environment
High frequency of BRAF mutations in nevi
To evaluate the timing of mutations in BRAF (v-raf murine sarcoma viral oncogene homolog B1) during melanocytic neoplasia, we carried out mutation analysis on microdissected melanoma and nevi samples. We observed mutations resulting in the V599E amino-acid substitution in 41 of 60 (68%) melanoma metastases, 4 of 5 (80%) primary melanomas and, unexpectedly, in 63 of 77 (82%) nevi. These data suggest that mutational activation of the RAS/RAF/MAPK pathway in nevi is a critical step in the initiation of melanocytic neoplasia but alone is insufficient for melanoma tumorigenesis
The Neural Processes Underlying Self-Agency
Self-agency (SA) is the individual's perception that an action is the consequence of his/her own intention. The neural networks underlying SA are not well understood. We carried out a novel, ecologically valid, virtual-reality experiment using blood oxygen level–dependent functional magnetic resonance imaging (fMRI) where SA could be modulated in real-time while subjects performed voluntary finger movements. Behavioral testing was also performed to assess the explicit judgment of SA. Twenty healthy volunteers completed the experiment. Results of the behavioral testing demonstrated paradigm validity along with the identification of a bias that led subjects to over- or underestimate the amount of control they had. The fMRI experiment identified 2 discrete networks. These leading and lagging networks likely represent a spatial and temporal flow of information, with the leading network serving the role of mismatch detection and the lagging network receiving this information and mediating its elevation to conscious awareness, giving rise to SA
Proteomic Analysis of Nuclei Dissected from Fixed Rat Brain Tissue Using Expression Microdissection
Expression
microdissection (xMD) is a high-throughput, operator-independent technology
that enables the procurement of specific cell populations from tissue
specimens. In this method, histological sections are first stained
for cellular markers via either chemical or immuno-guided methods,
placed in close contact with an ethylene vinyl acetate (EVA) film,
and exposed to a light source. The focal, transient heating of the
stained cells or subcellular structures melts the EVA film selectively
to the targets for procurement. In this report, we introduce a custom-designed
flashcube system that permits consistent and reproducible microdissection
of nuclei across an FFPE rat brain tissue section in milliseconds.
In addition, we present a method to efficiently recover and combine
captured proteins from multiple xMD films. Both light and scanning
electron microscopy demonstrated captured nuclear structures. Shotgun
proteomic analysis of the samples showed a significant enrichment
in nuclear localized proteins, with an average 25% of recovered proteins
localized to the nucleus, versus 15% for whole tissue controls (<i>p</i> < 0.001). Targeted mass spectrometry using multiple
reaction monitoring (MRM) showed more impressive data, with a 3-fold
enrichment in histones, and a concurrent depletion of proteins localized
to the cytoplasm, cytoskeleton, and mitochondria. These data demonstrate
that the flashcube-xMD technology is applicable to the proteomic study
of a broad range of targets in molecular pathology
Proteomic Analysis of Nuclei Dissected from Fixed Rat Brain Tissue Using Expression Microdissection
Expression
microdissection (xMD) is a high-throughput, operator-independent technology
that enables the procurement of specific cell populations from tissue
specimens. In this method, histological sections are first stained
for cellular markers via either chemical or immuno-guided methods,
placed in close contact with an ethylene vinyl acetate (EVA) film,
and exposed to a light source. The focal, transient heating of the
stained cells or subcellular structures melts the EVA film selectively
to the targets for procurement. In this report, we introduce a custom-designed
flashcube system that permits consistent and reproducible microdissection
of nuclei across an FFPE rat brain tissue section in milliseconds.
In addition, we present a method to efficiently recover and combine
captured proteins from multiple xMD films. Both light and scanning
electron microscopy demonstrated captured nuclear structures. Shotgun
proteomic analysis of the samples showed a significant enrichment
in nuclear localized proteins, with an average 25% of recovered proteins
localized to the nucleus, versus 15% for whole tissue controls (<i>p</i> < 0.001). Targeted mass spectrometry using multiple
reaction monitoring (MRM) showed more impressive data, with a 3-fold
enrichment in histones, and a concurrent depletion of proteins localized
to the cytoplasm, cytoskeleton, and mitochondria. These data demonstrate
that the flashcube-xMD technology is applicable to the proteomic study
of a broad range of targets in molecular pathology
KDM5 histone demethylases repress immune response via suppression of STING
<div><p>Cyclic GMP-AMP (cGAMP) synthase (cGAS) stimulator of interferon genes (STING) senses pathogen-derived or abnormal self-DNA in the cytosol and triggers an innate immune defense against microbial infection and cancer. STING agonists induce both innate and adaptive immune responses and are a new class of cancer immunotherapy agents tested in multiple clinical trials. However, <i>STING</i> is commonly silenced in cancer cells via unclear mechanisms, limiting the application of these agonists. Here, we report that the expression of <i>STING</i> is epigenetically suppressed by the histone H3K4 lysine demethylases KDM5B and KDM5C and is activated by the opposing H3K4 methyltransferases. The induction of <i>STING</i> expression by KDM5 blockade triggered a robust interferon response in a cytosolic DNA-dependent manner in breast cancer cells. This response resulted in resistance to infection by DNA and RNA viruses. In human tumors, <i>KDM5B</i> expression is inversely associated with <i>STING</i> expression in multiple cancer types, with the level of intratumoral CD8<sup>+</sup> T cells, and with patient survival in cancers with a high level of cytosolic DNA, such as human papilloma virus (HPV)-positive head and neck cancer. These results demonstrate a novel epigenetic regulatory pathway of immune response and suggest that KDM5 demethylases are potential targets for antipathogen treatment and anticancer immunotherapy.</p></div