6,220 research outputs found
Identification of caspase 3 motifs and critical aspartate residues in human Phospholipase D1b and Phopsholipase D2a
Stimulation of mammalian cells frequently initiates phospholipase D-catalysed
hydrolysis of phosphatidylcholine in the plasma membrane to yield phosphatidic acid
(PA) a novel lipid messenger. PA plays a regulatory role in important cellular
processes such as secretion, cellular shape change and movement. A number of
studies have highlighted that PLD-based signalling also plays a pro-mitogenic and
pro-survival role in cells and therefore anti-apoptotic. We show that human PLD1b
and PLD2a contain functional caspase-3 cleavage sites and identify the critical
aspartate residues within PLD1b that affect its activation by phorbol esters and
attenuate phosphatidylcholine hydrolysis during apoptosis
MethylPurify: tumor purity deconvolution and differential methylation detection from single tumor DNA methylomes
We propose a statistical algorithm MethylPurify that uses regions with bisulfite reads showing discordant methylation levels to infer tumor purity from tumor samples alone. MethylPurify can identify differentially methylated regions (DMRs) from individual tumor methylome samples, without genomic variation information or prior knowledge from other datasets. In simulations with mixed bisulfite reads from cancer and normal cell lines, MethylPurify correctly inferred tumor purity and identified over 96% of the DMRs. From patient data, MethylPurify gave satisfactory DMR calls from tumor methylome samples alone, and revealed potential missed DMRs by tumor to normal comparison due to tumor heterogeneity. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0419-x) contains supplementary material, which is available to authorized users
Global Coronal Waves
After the {\em Solar and Heliospheric Observatory} ({\em SOHO}) was launched
in 1996, the aboard Extreme Ultraviolet Imaging Telescope (EIT) observed a
global coronal wave phenomenon, which was initially named "EIT wave" after the
telescope. The bright fronts are immediately followed by expanding dimmings. It
has been shown that the brightenings and dimmings are mainly due to plasma
density increase and depletion, respectively. Such a spectacular phenomenon
sparked long-lasting interest and debates. The debates were concentrated on two
topics, one is about the driving source, and the other is about the nature of
this wavelike phenomenon. The controversies are most probably because there may
exist two types of large-scale coronal waves that were not well resolved before
the {\em Solar Dynamics Observatory} ({\em SDO}) was launched: one is a
piston-driven shock wave straddling over the erupting coronal mass ejection
(CME), and the other is an apparently propagating front, which may correspond
to the CME frontal loop. Such a two-wave paradigm was proposed more than 13
years ago, and now is being recognized by more and more colleagues. In this
paper, we review how various controversies can be resolved in the two-wave
framework and how important it is to have two different names for the two types
of coronal waves.Comment: 14 pages, 6 figures, a review pape
Photoactivated chemotherapy (PACT) : the potential of excited-state d-block metals in medicine
The fields of phototherapy and of inorganic chemotherapy both have long histories. Inorganic photoactivated chemotherapy (PACT) offers both temporal and spatial control over drug activation and has remarkable potential for the treatment of cancer. Following photoexcitation, a number of different decay pathways (both photophysical and photochemical) are available to a metal complex. These pathways can result in radiative energy release, loss of ligands or transfer of energy to another species, such as triplet oxygen. We discuss the features which need to be considered when developing a metal-based anticancer drug, and the common mechanisms by which the current complexes are believed to operate. We then provide a comprehensive overview of PACT developments for complexes of the different d-block metals for the treatment of cancer, detailing the more established areas concerning Ti, V, Cr, Mn, Re, Fe, Ru, Os, Co, Rh, Pt, and Cu and also highlighting areas where there is potential for greater exploration. Nanoparticles (Ag, Au) and quantum dots (Cd) are also discussed for their photothermal destructive potential. We also discuss the potential held in particular by mixed-metal systems and Ru complexes
CRISPR-Cas9-Based Functional Interrogation of Unconventional Translatome Reveals Human Cancer Dependency on Cryptic Non-Canonical Open Reading Frames
Emerging evidence suggests that cryptic translation beyond the annotated translatome produces proteins with developmental or physiological functions. However, functions of cryptic non-canonical open reading frames (ORFs) in cancer remain largely unknown. To fill this gap and systematically identify colorectal cancer (CRC) dependency on non-canonical ORFs, we apply an integrative multiomic strategy, combining ribosome profiling and a CRISPR-Cas9 knockout screen with large-scale analysis of molecular and clinical data. Many such ORFs are upregulated in CRC compared to normal tissues and are associated with clinically relevant molecular subtypes. We confirm the in vivo tumor-promoting function of the microprotein SMIMP, encoded by a primate-specific, long noncoding RNA, the expression of which is associated with poor prognosis in CRC, is low in normal tissues and is specifically elevated in CRC and several other cancer types. Mechanistically, SMIMP interacts with the ATPase-forming domains of SMC1A, the core subunit of the cohesin complex, and facilitates SMC1A binding to cis-regulatory elements to promote epigenetic repression of the tumor-suppressive cell cycle regulators encoded by CDKN1A and CDKN2B. Thus, our study reveals a cryptic microprotein as an important component of cohesin-mediated gene regulation and suggests that the \u27dark\u27 proteome, encoded by cryptic non-canonical ORFs, may contain potential therapeutic or diagnostic targets
Application of Graphene within Optoelectronic Devices and Transistors
Scientists are always yearning for new and exciting ways to unlock graphene's
true potential. However, recent reports suggest this two-dimensional material
may harbor some unique properties, making it a viable candidate for use in
optoelectronic and semiconducting devices. Whereas on one hand, graphene is
highly transparent due to its atomic thickness, the material does exhibit a
strong interaction with photons. This has clear advantages over existing
materials used in photonic devices such as Indium-based compounds. Moreover,
the material can be used to 'trap' light and alter the incident wavelength,
forming the basis of the plasmonic devices. We also highlight upon graphene's
nonlinear optical response to an applied electric field, and the phenomenon of
saturable absorption. Within the context of logical devices, graphene has no
discernible band-gap. Therefore, generating one will be of utmost importance.
Amongst many others, some existing methods to open this band-gap include
chemical doping, deformation of the honeycomb structure, or the use of carbon
nanotubes (CNTs). We shall also discuss various designs of transistors,
including those which incorporate CNTs, and others which exploit the idea of
quantum tunneling. A key advantage of the CNT transistor is that ballistic
transport occurs throughout the CNT channel, with short channel effects being
minimized. We shall also discuss recent developments of the graphene tunneling
transistor, with emphasis being placed upon its operational mechanism. Finally,
we provide perspective for incorporating graphene within high frequency
devices, which do not require a pre-defined band-gap.Comment: Due to be published in "Current Topics in Applied Spectroscopy and
the Science of Nanomaterials" - Springer (Fall 2014). (17 pages, 19 figures
Visualizing Individual Nitrogen Dopants in Monolayer Graphene
In monolayer graphene, substitutional doping during growth can be used to
alter its electronic properties. We used scanning tunneling microscopy (STM),
Raman spectroscopy, x-ray spectroscopy, and first principles calculations to
characterize individual nitrogen dopants in monolayer graphene grown on a
copper substrate. Individual nitrogen atoms were incorporated as graphitic
dopants, and a fraction of the extra electron on each nitrogen atom was
delocalized into the graphene lattice. The electronic structure of
nitrogen-doped graphene was strongly modified only within a few lattice
spacings of the site of the nitrogen dopant. These findings show that chemical
doping is a promising route to achieving high-quality graphene films with a
large carrier concentration.Comment: Science 201
Measurement of the Masses and Widths of the Sigma_c^++ and Sigma_c^0 Charmed Baryons
Using data recorded by the CLEO II and CLEO II.V detector configurations at
CESR, we report new measurements of the masses of the Sigma_c^{++} and
Sigma_c^0 charmed baryons, and the first measurements of their intrinsic
widths. We find M(Sigma_c^{++}) - M(Lambda_c^+) = 167.4 +- 0.1 +- 0.2 MeV,
Gamma(Sigma_c^{++}) = 2.3 +- 0.2 +- 0.3 MeV, and M(Sigma_c^0) - M(Lambda_c^+) =
167.2 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^0) = 2.5 +- 0.2 +- 0.3 MeV, where the
uncertainties are statistical and systematic, respectively.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid
Communications. Reference [13] correcte
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