2,013 research outputs found
1-(4-Methylbenzylideneamino)pyridinium iodide
The title compound, C13H13N2
+·I−, is a derivative of 1-aminopyridinium iodide. The pyridine and benzene rings are oriented at a dihedral angle of 45.78 (3)°. In the crystal structure, weak intermolecular C—H⋯I hydrogen bonds link the molecules
An oligonucleotide microarray for microRNA expression analysis based on labeling RNA with quantum dot and nanogold probe
MicroRNAs (miRNAs) play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. They have diverse expression patterns and might regulate various developmental and physiological processes. Profiling miRNA expression is very helpful for studying biological functions of miRNAs. We report a novel miRNA profiling microarray, in which miRNAs were directly labeled at the 3′ terminus with biotin and hybridized with complementary oligo-DNA probes immobilized on glass slides, and subsequently detected by measuring fluorescence of quantum dots labeled with streptavidin bound to miRNAs through streptavidin–biotin interaction. The detection limit of this microarray for miRNA was ∼0.4 fmol, and the detection dynamic range spanned about 2 orders of magnitude. We made a model microarray to profile 11 miRNAs from leaf and root of rice (Oryza sativa L. ssp. indica) seedlings. The analysis results of the miRNAs had a good reproducibility and were consistent with the northern blot result. To avoid using high-cost detection equipment, colorimetric detection, a method based on nanogold probe coupled with silver enhancement, was also successfully introduced into miRNA profiling microarray detection
Insight-HXMT Measurements of the Diffuse X-ray Background
We present an X-ray spectrum of the diffuse X-ray background (DXRB) between
1.5 and 120 keV, as measured with the Low-Energy Detector (LE) and the
High-Energy Detector (HE) aboard the Insight-HXMT satellite, based on
'blank-sky' observations. LE covers a nominal energy range of 1-15 keV and HE
20-250 keV, but calibration issues and data quality narrowed the energy range
for this work. The LE background was directly measured with `blind' detector
modules, while the HE background was derived from Earth-occultation data. With
the LE data alone, the measured DXRB spectrum can be well described by a power
law; fitting the LE and HE data jointly, however, a spectral cut-off must be
introduced in the model to account for the measurements above 30 keV. Modelling
the combined spectrum with a cut-off power law, the best-fit photon index is
1.40, normalisation ~ (at 1
keV), and cut-off energy 55 keV, after correcting for the effects of the Earth
albedo and atmospheric emission (which are significant in the HE band). Based
on the best-fit cut-off power law, we derived the spectral energy distribution
(SED) of the DXRB. The shape of the SED is in general agreement with the
published measurements, but the overall normalization is lower by varying
amounts, except for the HEAO-1 result, with which our result is in good
agreement.Comment: 9 pages, 14 figures, published in MNRA
CAMKs support development of acute myeloid leukemia.
BACKGROUND: We recently identified the human leukocyte immunoglobulin-like receptor B2 (LILRB2) and its mouse ortholog-paired Ig-like receptor (PirB) as receptors for several angiopoietin-like proteins (Angptls). We also demonstrated that PirB is important for the development of acute myeloid leukemia (AML), but exactly how an inhibitory receptor such as PirB can support cancer development is intriguing. RESULTS: Here, we showed that the activation of Ca (2+)/calmodulin-dependent protein kinases (CAMKs) is coupled with PirB signaling in AML cells. High expression of CAMKs is associated with a poor overall survival probability in patients with AML. Knockdown of CAMKI or CAMKIV decreased human acute leukemia development in vitro and in vivo. Mouse AML cells that are defective in PirB signaling had decreased activation of CAMKs, and the forced expression of CAMK partially rescued the PirB-defective phenotype in the MLL-AF9 AML mouse model. The inhibition of CAMK kinase activity or deletion of CAMKIV significantly slowed AML development and decreased the AML stem cell activity. We also found that CAMKIV acts through the phosphorylation of one of its well-known target (CREB) in AML cells. CONCLUSION: CAMKs are essential for the growth of human and mouse AML. The inhibition of CAMK signaling may become an effective strategy for treating leukemia
The human mediodorsal thalamus: Organization, connectivity, and function
The human mediodorsal thalamic nucleus (MD) is crucial for higher cognitive functions, while the fine anatomical organization of the MD and the function of each subregion remain elusive. In this study, using high-resolution data provided by the Human Connectome Project, an anatomical connectivity-based method was adopted to unveil the topographic organization of the MD. Four fine-grained subregions were identified in each hemisphere, including the medial (MDm), central (MDc), dorsal (MDd), and lateral (MDl), which recapitulated previous cytoarchitectonic boundaries from histological studies. The subsequent connectivity analysis of the subregions also demonstrated distinct anatomical and functional connectivity patterns, especially with the prefrontal cortex. To further evaluate the function of MD subregions, partial least squares analysis was performed to examine the relationship between different prefrontal-subregion connectivity and behavioral measures in 1012 subjects. The results showed subregion-specific involvement in a range of cognitive functions. Specifically, the MDm predominantly subserved emotional-cognition domains, while the MDl was involved in multiple cognitive functions especially cognitive flexibility and inhibition. The MDc and MDd were correlated with fluid intelligence, processing speed, and emotional cognition. In conclusion, our work provides new insights into the anatomical and functional organization of the MD and highlights the various roles of the prefrontal-thalamic circuitry in human cognition
Detection of spin bias in four-terminal quantum-dot ring
In this work, we show that in a four-quantum-dot ring, via introducing a
local Rashba spin-orbit interaction the spin bias in the transverse terminals
can be detected by observing the charge currents in the longitudinal probes. It
is found that due to the Rashba interaction, the quantum interference in this
system becomes spin-dependent and the opposite-spin currents induced by the
spin bias can present different magnitudes, so charge currents emerge. Besides,
the charge currents rely on both the magnitude and spin polarization direction
of the spin bias. It is believed that this method provides an electrical but
practical scheme to detect the spin bias (or the spin current).Comment: 6 pages, 5 figure
Restoration of mutant K-Ras repressed miR-199b inhibits K-Ras mutant non-small cell lung cancer progression
Background: miRNAs play crucial role in the progression of K-Ras-mutated nonsmall cell lung cancer (NSCLC). However, most studies have focused on miRNAs that target K-Ras. Here, we investigated miRNAs regulated by mutant K-Ras and their functions. Methods: miRNAs regulated by mutant K-Ras were screened using miRNA arrays. miR-199b expression levels were measured by qRT-PCR. The protein expression levels were measured using Western blot and immunohistochemistry. The effects of miR-199b on NSCLC were examined both in vitro and in vivo by overexpressing or inhibiting miR-199b. DNA methylation was measured by bisulfite sequencing. Results: An inverse correlation was observed between K-Ras mutation status and miR-199b levels in NSCLC specimens and cell lines. The inhibition of miR-199b stimulated NSCLC growth and metastasis, while restoration of miR-199b suppressed K-Ras mutation-driven lung tumorigenesis as well as K-Ras-mutated NSCLC growth and metastasis. miR-199b inactivated ERK and Akt pathways by targeting K-Ras, KSR2, PIK3R1, Akt1, and Rheb1. Furthermore, we determined that mutant K-Ras inhibits miR-199b expression by increasing miR-199b promoter methylation. Conclusion: Our findings suggest that mutant K-Ras plays an oncogenic role through downregulating miR-199b in NSCLC and that overexpression of miR-199b is a novel strategy for the treatment of K-Ras-mutated NSCLC.This work was supported by the National Natural Science Foundation of China (81672283 to H.J.) and the Startup Fund for Talented Scholars of Daping Hospital and Research Institute of Surgery, Third Military Medical University (to H.J. and C.-X.X).
Investigation of Spatial and Temporal Trends in Water Quality in Daya Bay, South China Sea
The objective is to identify the spatial and temporal variability of the hydrochemical quality of the water column in a subtropical coastal system, Daya Bay, China. Water samples were collected in four seasons at 12 monitoring sites. The Southeast Asian monsoons, northeasterly from October to the next April and southwesterly from May to September have also an important influence on water quality in Daya Bay. In the spatial pattern, two groups have been identified, with the help of multidimensional scaling analysis and cluster analysis. Cluster I consisted of the sites S3, S8, S10 and S11 in the west and north coastal parts of Daya Bay. Cluster I is mainly related to anthropogenic activities such as fish-farming. Cluster II consisted of the rest of the stations in the center, east and south parts of Daya Bay. Cluster II is mainly related to seawater exchange from South China Sea
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