1,626 research outputs found
CRISPR/Cas9-mediated gene manipulation to create single-amino-acid-substituted and floxed mice with a cloning-free method.
Clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology is a powerful tool to manipulate the genome with extraordinary simplicity and speed. To generate genetically modified animals, CRISPR/Cas9-mediated genome editing is typically accomplished by microinjection of a mixture of Cas9 DNA/mRNA and single-guide RNA (sgRNA) into zygotes. However, sgRNAs used for this approach require manipulation via molecular cloning as well as in vitro transcription. Beyond these complexities, most mutants obtained with this traditional approach are genetically mosaic, yielding several types of cells with different genetic mutations. Recently, a growing body of studies has utilized commercially available Cas9 protein together with sgRNA and a targeting construct to introduce desired mutations. Here, we report a cloning-free method to target the mouse genome by pronuclear injection of a commercial Cas9 protein:crRNA:tracrRNA:single-strand oligodeoxynucleotide (ssODN) complex into mouse zygotes. As illustration of this method, we report the successful generation of global gene-knockout, single-amino-acid-substituted, as well as floxed mice that can be used for conditional gene-targeting. These models were produced with high efficiency to generate non-mosaic mutant mice with a high germline transmission rate
Development of a high-density CHO-C system enables rapid protein production in 10 days
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The Clumpy Structure Of Five Star-bursting Dwarf Galaxies In The MaNGA Survey
The star-forming clumps in star-bursting dwarf galaxies provide valuable
insights into the understanding of the evolution of dwarf galaxies. In this
paper, we focus on five star-bursting dwarf galaxies featuring off-centered
clumps in the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA)
survey. Using the stellar population synthesis software FADO, we obtain the
spatially-resolved distribution of the star formation history, which allows us
to construct the -band images of the five galaxies at different ages. These
images can help us to probe the evolution of the morphological structures of
these galaxies. While images of stellar population older than 1 Gyr are
typically smooth, images of stellar population younger than 1 Gyr reveal
significant clumps, including multiple clumps which appear at different
locations and even different ages. To study the evolutionary connections of
these five galaxies to other dwarf galaxies before their star-forming clumps
appear, we construct the images of the stellar populations older than three age
nodes, and define them to be the images of the "host" galaxies. We find that
the properties such as the central surface brightness and the effective radii
of the hosts of the five galaxies are in between those of dwarf ellipticals
(dEs) and dwarf irregulars (dIrrs), with two clearly more similar to dEs and
one more similar to dIrrs. Among the five galaxies, 8257-3704 is particularly
interesting, as it shows a previous starburst event that is not quite visible
from its image, but only visible from images of the stellar population at
a few hundred million years. The star-forming clump associated with this event
may have appeared at around 600 Myr and disappeared at around 40 Myr.Comment: 21 pages, 16 figures, accepted for publication in RA
Pathophysiology of Neuropathic Pain in Type 2 Diabetes: Skin denervation and contact heat–evoked potentials
OBJECTIVE: Neuropathic pain due to small-fiber sensory neuropathy in type 2 diabetes can be diagnosed by skin biopsy with quantification of intra- epidermal nerve fiber ( IENF) density. There is, however, a lack of noninvasive physiological assessment. Contact heat-evoked potential ( CHEP ) is a newly developed approach to record cerebral responses of A fiber- mediated thermonociceptive stimuli. We investigated the diagnostic role of CHEP. RESEARCH DESIGN AND METHODS: From 2006 to 2009, there were 32 type 2 diabetic patients (20 males and 12 females, aged 51.63 10.93 years) with skin denervation and neuropathic pain. CHEPs were recorded with heat stimulations at the distal leg, where skin biopsy was performed. RESULTS: CHEP amplitude was reduced in patients compared with age- and sex-matched control subjects (14.8 15.6 vs. 33.7 10.1 V, P < 0.001). Abnormal CHEP patterns ( reduced amplitude or prolonged latency) were noted in 81.3 % of these patients. The CHEP amplitude was the most significant parameter correlated with IENF density (P = 0. 003) and pain perception to contact heat stimuli (P = 0.019) on multiple linear regression models. An excitability index was derived by calculating the ratio of the CHEP amplitude over the IENF density. This excitability index was higher in diabetic patients than in control subjects (P = 0.023), indicating enhanced brain activities in neuropathic pain. Among different neuropathic pain symptoms, the subgroup with evoked pain had higher CHEP amplitudes than the subgroup without evoked pain (P = 0.011). CONCLUSIONS: CHEP offers a noninvasive approach to evaluate the degeneration of thermonociceptive nerves in diabetic neuropathy by providing physiological correlates of skin denervation and neuropathic pain
FRBs' Brownian Motion on Time-Energy Bivariate Space
The origin of fast radio bursts (FRBs), the brightest cosmic explosion in
radio bands, remains unknown. Magnetar-related mechanisms are currently
favored. The searches for short-term periodicity that is naturally expected for
such fast-spinning compact objects, however, have failed. We introduce here a
novel method for a comprehensive analysis of active FRBs' behaviors in the
time-energy domain. Using ``Pincus Index'' and ``Maximum Lyapunov Exponent'',
we were able to quantify the stochasticity and chaos, respectively, of the
bursting events and put FRBs in the context of common transient physical
phenomena, such as pulsars, earthquakes, and solar flares. In the bivariate
time-energy domain, repeated FRB bursts' behaviors deviate significantly (more
random, less chaotic) from pulsars, earthquakes, and solar flares. FRB bursts
wander in time-energy space stochastically, akin to Brownian motions. The high
degree of stochasticity suggests complex and even multi-origins for FRBs.Comment: 6 pages, 4 figures, submitte
Sliding of coherent twin boundaries
Coherent twin boundaries (CTBs) are internal interfaces that can play a key role in markedly enhancing the strength of metallic materials while preserving their ductility. They are known to accommodate plastic deformation primarily through their migration, while experimental evidence documenting large-scale sliding of CTBs to facilitate deformation has thus far not been reported. We show here that CTB sliding is possible whenever the loading orientation enables the Schmid factors of leading and trailing partial dislocations to be comparable to each other. This theoretical prediction is confirmed by real-Time transmission electron microscope experimental observations during uniaxial deformation of copper pillars with different orientations and is further validated at the atomic scale by recourse to molecular dynamics simulations. Our findings provide mechanistic insights into the evolution of plasticity in heavily twinned face-centered cubic metals, with the potential for optimizing mechanical properties with nanoscale CTBs in material design
A Workflow to Predict the Present-day in-situ Stress Field in Tectonically Stable Regions
Knowledge of the present-day in-situ stress distribution is greatly important for better understanding of conventional and unconventional hydrocarbon reservoirs in many aspects, e.g., reservoir management, wellbore stability assessment, etc. In tectonically stable regions, the present-day in-situ stress field in terms of stress distribution is largely controlled by lithological changes, which can be predicted through a numerical simulation method incorporating specific mechanical properties of the subsurface reservoir. In this study, a workflow was presented to predict the present-day in-situ stress field based on the finite element method (FEM). Sequentially, it consists of: i) building a three-dimensional (3D) geometric framework, ii) creating a 3D petrophysical parameter field, iii) integrating the geometric framework with petrophysical parameters, iv) setting up a 3D heterogeneous geomechanical model, and finally, v) calculating the present-day in-situ stress distribution and calibrating the prediction with measured stress data, e.g., results from the extended leak-off tests (XLOTs). The approach was successfully applied to the Block W in Ordos Basin of central China. The results indicated that the workflow and models presented in this study could be used as an effective tool to provide insights into stress perturbations in subsurface reservoirs and geological references for subsequent analysis
SIMD Everywhere Optimization from ARM NEON to RISC-V Vector Extensions
Many libraries, such as OpenCV, FFmpeg, XNNPACK, and Eigen, utilize Arm or
x86 SIMD Intrinsics to optimize programs for performance. With the emergence of
RISC-V Vector Extensions (RVV), there is a need to migrate these performance
legacy codes for RVV. Currently, the migration of NEON code to RVV code
requires manual rewriting, which is a time-consuming and error-prone process.
In this work, we use the open source tool, "SIMD Everywhere" (SIMDe), to
automate the migration. Our primary task is to enhance SIMDe to enable the
conversion of ARM NEON Intrinsics types and functions to their corresponding
RVV Intrinsics types and functions. For type conversion, we devise strategies
to convert Neon Intrinsics types to RVV Intrinsics by considering the vector
length agnostic (vla) architectures. With function conversions, we analyze
commonly used conversion methods in SIMDe and develop customized conversions
for each function based on the results of RVV code generations. In our
experiments with Google XNNPACK library, our enhanced SIMDe achieves speedup
ranging from 1.51x to 5.13x compared to the original SIMDe, which does not
utilize customized RVV implementations for the conversions
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