460 research outputs found
A New Cationic Fluorescent Probe for HSO3− Based on Bisulfite Induced Aggregation Self-Assembly
In comparison with the numerous studies that have centered on developing molecular frameworks for the functionalization of fluorescent materials, less research has addressed the influence of the side chains, despite such appendages contributing significantly to the properties and applications of fluorescent materials. In this work, a new series of cationic fluorescent probes with AIE characteristics have been developed, which exhibit unique sensitivity for charge-diffusion anions, namely HSO3−, via the interactions of ions and the cooperation of the controllable hydrophobicity. The impact of the alkyl chain length attached at the cationic probes suggested that the fluorescent intensity and sensitivity of the probes could be partially enhanced by adjusting their aggregation tendency through the action of the hydrophobic effect under aqueous conditions. DLS and SEM images indicated that different particle sizes and new morphologies of the probes were formed in the anion-recognition-triggered self-assembly process, which could be attributed to the composite effect of electrostatic actions, Van der Waals forces and π-π stacking
Evaluation of parameters affecting Agrobacterium-mediated transient expression in citrus
Abstract Agrobacterium-mediated transient expression assays are a convenient alternative to stable expression because they are simple, easy to perform, and achieve gene expression rapidly. This study investigated the factors affecting transient gene expression efficiency in citrus by observing the cryo-sectioning of leaf samples under a laser confocal microscope. These factors included the composition of the infiltration buffer, the Agrobacterium cell density, the leaf development stage, the incubation temperature, and plant genotype. The highest transient expression level of yellow fluorescent protein (YFP) was detected in Mexican lime (Citrus aurantifolia) on the third day after the intermediate-aged leaves were infiltrated with the improved infiltration buffer 1 (15 mmol L−1 2-(N-morpholino) ethanesulfonic acid, 10 mmol L−1 MgCI2, and 200 pmol L−1 acetosyringone), which had an optical density of 0.8 and was incubated at 22°C. Additionally, this transient expression assay was applied to other citrus genotypes. Of note, trifoliate orange (Poncirus trifoliata) and kumquat (Fortunella obovate) had higher expression efficiency than other six genotypes of the Citrus genus. Our study provides research basis for the selection of optimization strategies in transient gene expression and improves the method for available genome investigation in citrus
Different physiological roles of insulin receptors in mediating nutrient metabolism in zebrafish
Insulin, the most potent anabolic hormone, is critical for somatic growth and metabolism in vertebrates. Type 2 diabetes, which is the primary cause of hyperglycemia. results from an inability of insulin to signal glycolysis and gluconeogenesis. Our previous study showed that double knockout of insulin receptor a (insra) and b (insrb) caused beta-cell hyperplasia and lethality from 5 to 16 days postfertilization (dpf) (Yang BY, Zhai G, Gong YL, Su JZ, Han D, Yin Z, Xie SQ. Sci Bull (Beijing) 62: 486-492, 2017). In this study, we characterized the physiological roles of Insra and Insrb. in somatic growth and fueling metabolism, respectively. A high-carbohydrate diet was provided for insulin receptor knockout zebrafish from 60 to 120 dpf to investigate phenotype inducement and amplification. We observed hyperglycemia in both insra-/- fish and insrb-/- fish. Impaired growth hormone signaling, increased visceral adiposity, and fatty liver were detected in insrb-/- fish, which are phenotypes similar to the lipodystrophy observed in mammals. More importantly, significantly diminished protein levels of P-PPAR alpha, P-STATS, and IGF-1 were also observed in insrb-/- fish. In insra-/- fish, we observed increased protein content and decreased lipid content of the whole body. Taken together, although Insra and Insrb show overlapping roles in mediating glucose metabolism through the insulin-signaling pathway, Insrb is more prone to promoting lipid catabolism and protein synthesis through activation of the growth hormone-signaling pathway, whereas Insra primarily acts to promote lipid synthesis via glucose utilization.</p
Coherent phonon dynamics in spatially separated graphene mechanical resonators
Vibrational modes in mechanical resonators provide a promising candidate to
interface and manipulate classical and quantum information. The observation of
coherent dynamics between distant mechanical resonators can be a key step
towards scalable phonon-based applications. Here we report tunable coherent
phonon dynamics with an architecture comprising three graphene mechanical
resonators coupled in series, where all resonators can be manipulated by
electrical signals on control gates. We demonstrate coherent Rabi oscillations
between spatially separated resonators indirectly coupled via an intermediate
resonator serving as a phonon cavity. The Rabi frequency fits well with the
microwave burst power on the control gate. We also observe Ramsey interference,
where the oscillation frequency corresponds to the indirect coupling strength
between these resonators. Such coherent processes indicate that information
encoded in vibrational modes can be transferred and stored between spatially
separated resonators, which can open the venue of on-demand phonon-based
information processing
BCL11A overexpression predicts survival and relapse in non-small cell lung cancer and is modulated by microRNA-30a and gene amplification
The Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Release Six to Nine
We report the fourth installment in the series of the Large Sky Area
Multi-Object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey, which
includes quasars observed between September, 2017 and June, 2021. There are in
total 13,066 quasars reliably identified, of which 6,685 are newly discovered
that are not reported in the SDSS DR14 quasar catalog or Million Quasars
catalog. Because LAMOST does not provide accurate absolute flux calibration, we
re-calibrate the spectra with the SDSS/Pan-STARRS1 multi-band photometric data.
The emission line properties of H, H, Mg\,{\sc ii} and C\,{\sc
iv}, and the continuum luminosities are measured by fitting the re-calibrated
spectra. We also estimate the single-epoch virial black hole masses () using the derived emission line and continuum parameters. This is the
first time that the emission line and continuum fluxes were estimated based on
LAMOST re-calibrated quasar spectra. The catalog and spectra for these quasars
are available online. After the nine-year LAMOST quasar survey, there are in
total 56,175 identified quasars, of which 24,127 are newly discovered. The
LAMOST quasar survey not only discovers a great number of new quasars, but also
provides a database for investigating the spectral variability of the quasars
observed by both LAMOST and SDSS, and finding rare quasars including
changing-look quasars and broad absorption line quasars.Comment: arXiv admin note: text overlap with arXiv:1811.01570, Accepted by
ApJ
Lobocrassins A–E: New Cembrane-Type Diterpenoids from the Soft Coral Lobophytum crassum
Five new cembrane-type diterpenoids, lobocrassins A–E (1–5), were isolated from the soft coral Lobophytum crassum. The structures of cembranes 1–5 were established by spectroscopic and chemical methods and by comparison of the spectral data with those of known cembrane analogues. Lobocrassin A (1) is the first cembranoid possessing an α-chloromethyl-α-hydroxy-γ-lactone functionality and is the first chlorinated cembranoid from soft corals belonging to the genus Lobophytum. Lobocrassins B (2) and C (3) were found to be the stereoisomers of the known cembranes, 14-deoxycrassin (6) and pseudoplexaurol (7), respectively. Lobocrassin B (2) exhibited modest cytotoxicity toward K562, CCRF-CEM, Molt4, and HepG2 tumor cells and displayed significant inhibitory effects on the generation of superoxide anion and the release of elastase by human neutrophils
Menelloides C and D, New Sesquiterpenoids from the Gorgonian Coral Menella sp
Two new metabolites, including a lindenane-type sesquiterpenoid, menelloide C (1), and a germacrane-type sesquiterpenoid, menelloide D (2), were isolated from a Formosan gorgonian coral identified as Menella sp. The structures of 1 and 2 were established by spectroscopic methods and 2 displayed a weak inhibitory effect on the release of elastase by human neutrophils
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