A mimicking-enzyme-based colorimetric aptasensor was developed for the detection of kanamycin (KANA) in milk using magnetic loop-DNA-NMOF-Pt (m-L-DNA) probes and catalytic hairpin assembly ...(CHA)-assisted target recycling for signal amplification. The m-L-DNA probes were constructed via hybridization of hairpin DNA H1 (containing aptamer sequence) immobilized magnetic beads (m-H1) and signal DNA (sDNA, partial hybridization with H1) labeled nano Fe-MIL-88NH
-Pt (NMOF-Pt-sDNA). In the presence of KANA and complementary hairpin DNA H2, the m-L-DNA probes decomposed and formed an m-H1/KANA intermediate, which triggered the CHA reaction to form a stable duplex strand (m-H1-H2) while releasing KANA again for recycling. Consequently, numerous NMOF-Pt-sDNA as mimicking enzymes can synergistically catalyze 3,3',5,5'-tetramethylbenzidine (TMB) for color development. The aptasensor exhibited high selectivity and sensitivity for KANA in milk with a detection limit of 0.2 pg mL
within 30 min. The assay can be conveniently extended for on-site screening of other antibiotics in foods by simply changing the base sequence of the probes.
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•The retrograde eclogite in Danshuiquan locality recorded clockwise P–T path.•The extensive HP–UHT overprint eliminated most of the peak stage records.•The eclogite was exhumed from ...eclogite-facies to granulite-facies within 16 Ma.•The eastern and western SAT experienced differential exhumation process.•Local mantle heating contribute to the fast exhumation in the eastern segment.
South Altyn Tagh contains ultrahigh-pressure (UHP) terranes that have been exhumed from ~300 km mantle depth. Previous zircon U–Pb geochronology has yielded an eclogite-facies age of ca. 500 Ma and a high-pressure (HP) granulite-facies retrograde age of ca. 450 Ma in the Jianggalesayi area in the western segment of South Altyn Tagh. However, in the eastern segment (Yinggelisayi and Danshuiquan localities), an age range of 500–480 Ma has been determined, and it remains uncertain as to whether this age range represents the timing of the peak metamorphic stage or the retrograde overprint. Our study of newly discovered retrograde eclogite in the Danshuiquan locality shows that it underwent three stages of metamorphism, under eclogite-facies, HP granulite-facies and amphibolite-facies P–T conditions of 2.5–4.0 GPa and 870–1050 °C, 2.0–1.4 GPa and 830–940 °C, and 0.7–1.3 GPa and 704–880 °C, respectively. The decompression-dominated P–T path evolved mainly after crossing the solidus, indicating marked retrograde modification under melt-bearing conditions. LA–ICP–MS and SIMS zircon U–Pb dating yielded ca. 500 Ma eclogite-facies and ca. 484 Ma granulite-facies retrograde ages and a later retrograde age of ca. 452 Ma. The clockwise P–T–t path indicates rapid exhumation from eclogite-facies to granulite-facies within around 16 Myr, which is faster than that of the UHP rocks in the western segment. Thus, the HP–UHP rocks in South Altyn Tagh suggest a differential exhumation process for the eastern and western segments. The distinct HP–UHT metamorphism and rapid exhumation of (U)HP rocks in the eastern segment likely resulted from local mantle heating. The continuing P–T evolution of the (U)HP rocks under UHT conditions during exhumation led to a pervasive granulite-facies overprint in the eastern segment of the South Altyn Tagh. The rapid exhumation recorded in the eastern segment provides valuable insights into the exhumation mechanism of ultra-deep subducted UHP terranes.
A growing number of reports suggested that the inhibitor targeting cyclin-dependent kinases (CDK) 2/4/6 can act as a more feasible chemotherapy strategy. In the present paper, a novel PROTAC molecule ...was developed based on the structure of Ribociclib’s derivative. In malignant melanoma cells, the degrader can not only degrade CDK 2/4/6 simultaneously and effectively, but also remarkably induce cell cycle arrest and apoptosis of melanoma cells. Moreover, PROTAC molecules with CRBN ligands always have poor oral bioavailability. We developed the orally bioavailable prodrug for the first time. It would provide general solution for oral administration of the PROTAC molecules, derived from CRBN ligands, for animal test conveniently.
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•Compound 3 is an efficient PROTAC molecule which can degrade CDK 2/4/6 simultaneously and effectively.•Compound 3 Remarkably inhibit the growth of melanoma cells.•The first orally bioavailable prodrug was developed for the PROTAC molecules with CRBN ligands.•The oral bioavailability of compound 11 is up to 68%.
Four episodes of granitic rocks at 517, 501-496, 462-451, and 426-385 Ma occurred in the South Altyn subduction-collision complex. The first episode of granite emplacement predates the formation of ...the ophiolite type mafic rock （〉500 Ma）, and the three subsequent episodes can be temporally correlated to high-pressure （HP） to ultrahigh-pressure （UHP） metamorphism at ca 500 Ma, retrograde granulite-facies metamorphism at ca. 450 Ma, and amphibolite-facies metamorphism at ca. 420 Ma, re- spectively. A comprehensive study of these granitic rocks, along with the regional geological background, mafic-ultramafic rocks, and HP-UHP metamorphism, indicates that the four episodes of granitic magmatism are sequentially derived from the partial melting of the earlier subducted oceanic crust at 517 Ma, the thickened continental crust due to continental subduction at ca. 500 Ma, the mid-upper crust in response to slab breakoff at ca. 450 Ma, and the tectonic transition from contraction to extension at ca. 420 Ma. The formation age of 517 Ma for oceanic adakite provides a direct constraint on the time of the oce- anic subduction in South Altyn. In addition, there is a ca. i0 Myr interval between the oceanic subduction to the continental deep subduction, suggesting that the Early Paleozoic tectonic evolution might have been a successive process in South Altyn. The four episodes of formation of granitic rocks, mafic-ultramafic rocks, and HP-UHP metamorphic rocks have fully recorded the tectonic evolution, beginning with the oceanic subduction, followed by continental subduction, and later exhumation dur- ing the Early Paleozoic in South Altyn.
► Using Fe3O4@GO as the sorbent of MSPE. ► The first time using Fe3O4@GO to adsorb trace levels of PCBs in water samples. ► Investigation of Fe3O4@GO’s adsorption characteristics and sorption ...isotherm. ► Establishment of a highly selective and sensitive MSPE–GC–MS analytical method.
In this paper, Fe3O4 nanoparticle (Fe3O4 NPs) grafted graphene oxide (Fe3O4@GO), are successfully synthesized and used for the extraction of 2,4,4′-trichlorobiphenyl (PCB 28) from a large volume of water solution. With the magnetic solid-phase extraction (MSPE) technique based on the Fe3O4@GO sorbents, it requires only 30min to extract trace levels of PCB 28 from 200mL water samples. The Fe3O4@GO was analyzed by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier Transform infrared (FT-IR) spectroscopy, and Vibrating sample magnetometer (VSM), specific surface area analyzer. The adsorption kinetics, adsorption capacity of the adsorbent, and the effect of the solution pH and desorption conditions on the removal efficiency of PCB 28 were investigated. The second-order kinetic equation best describes the sorption kinetics. The results showed that Fe3O4@GO was a suitable material in the pre-concentration and immobilization of PCB 28 from large volumes of aqueous solutions in polychlorinated biphenyl pollution cleaning.
In this paper, we consider the graph signals are sparse in the graph Fourier domain and propose an iterative threshold compressed sensing reconstruction (ITCSR) algorithm to reconstruct sparse graph ...signals in the graph Fourier domain. The proposed ITCSR algorithm derives from the well-known compressed sensing by considering a threshold for sparsity-promoting reconstruction of the underlying graph signals. The proposed ITCSR algorithm enhances the performance of sparse graph signal reconstruction by introducing a threshold function to determine a suitable threshold. Furthermore, we demonstrate that the suitable parameters for the threshold can be automatically determined by leveraging the sparrow search algorithm. Moreover, we analytically prove the convergence property of the proposed ITCSR algorithm. In the experimental, numerical tests with synthetic as well as 3D point cloud data demonstrate the merits of the proposed ITCSR algorithm relative to the baseline algorithms.
Retrograde eclogite from the central part of the Qinling Complex, Zhaigen area of the North Qinling Belt, was studied using integrated petrology, mineral chemistry, pseudosection modeling, and ...geochronology. Microstructures and mineral relationships reveal five metamorphic stages and associated mineral assemblages as follows: (1) pre-peak stage M1, which is recorded by the inner cores of garnets together with mineral inclusions of clinopyroxene (Cpx1)+amphibole (Am1)+plagioclase (Pl1)±quartz±rutile, occurred under conditions of 760–770°C and 11.4–14.0kbar; (2) eclogite-facies stage M2, recorded by garnet cores+relic omphacite (with a high jadeite content up to 31%)+rutile+quartz under conditions of >16.7kbar and 679–765°C; (3) high-pressure granulite-facies stage M3, characterized by clinopyroxene (Cpx2)+plagioclase (Pl2) symplectites under conditions of 14.5–15.6kbar and 800–850°C; (4) medium-pressure granulite-facies stage M4, characterized by the growth of plagioclase+orthopyroxene coronas around garnet under conditions of 8.3–10kbar and 795–855°C; and (5) retrogressive amphibolite-facies stage M5, which is represented by amphibole (Am3)+plagioclase (Pl3) kelyphitic rims around garnet at conditions of <4kbar and <620°C. Based on Laser Raman analysis of mineral inclusions, cathodoluminescence images, in situ trace element concentrations from different domains within zircon grains, and LA-ICP-MS and SHRIMP U–Pb dating, the protolith age of the Zhaigen retrograde eclogite is suggested at 786±10Ma and the eclogite-facies metamorphic age recorded by metamorphic zircon cores is limited within 501–497Ma. The retrograde zircon rims display ages of 476–447Ma and 425Ma that probably reflect the timing of two stages of retrograde metamorphism, respectively. The mineral assemblages, P–T conditions, and zircon U–Pb data define a clockwise P–T–t path for the retrograde eclogite, suggesting that the Neoproterozoic protolith of the retrograde eclogite might evolved into continental subduction and eclogite-facies metamorphism during 501–497Ma before undergoing retrograde metamorphism during an initial stage of exhumation to middle–upper crust level at 474–447Ma and subsequent exhumation to shallow upper crust at ~420Ma.
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•A granulite-facies overprint eclogite is identified in North Qinling Belt.•Five metamorphic stages are recognized from this eclogite.•A clockwise P–T–t path is obtained by combining pseudosection and geochronology.•The eclogites record a single cycle of subduction and multiple stages of exhumation.
Background and aims
The plant growth promoting rhizobacteria have been extensively implicated in plant responses to changing environments. However, the action mechanisms still need to be elucidated. ...This study addressed the effect of
Paraburkholderia
sp. GD17 on rice seedlings in responses to salt stress.
Methods
The experiment consisted of GD17-inoculated and non-inoculated plants, with or without NaCl treatment. Physiological and biochemical parameters, and gene expression were analyzed.
Results
GD17 efficiently colonized inside roots, and provided a protection against salt stress. Following exposure to 68 mM of NaCl for 48 h, although the accumulation of Na
+
was not affected in GD17-inoculated (+ GD17) roots relative to non-inoculated ones, its concentration was substantially reduced in + GD17 shoots. The contents of K and other mineral elements were higher in + GD17 plants. The expression of Na
+
and K
+
transporter-encoding genes generally presented a higher level in + GD17 plants. The antioxidative defense especially related to the removal of H
2
O
2
was more strongly activated in + GD17 plants. Correspondingly, salt-induced oxidative damage was significantly ameliorated. A substantial increase in proline content and gene expression was observed in + GD17 plants. Additionally, the cell wall invertase-encoding gene displayed a dramatically higher expression level in + GD17 plants.
Conclusions
GD17 efficiently improved rice seedling tolerance to salt stress. The possible mechanisms might be associated with the absorption and redistribution of mineral elements, the vacuolar sequestration of Na
+
as well as exclusion of Na
+
, antioxidative defense, the production of proline, and the sucrose catabolism in apoplast.
Alkaline pectate lyases have biotechnological applications in plant fiber processing, such as ramie degumming. Previously, we characterized an alkaline pectate lyase from
S10, named BacPelA, which ...showed potential for enzymatic ramie degumming because of its high cleavage activity toward methylated pectins in alkaline conditions. However, BacPelA displayed poor thermo-alkaline stability. Here, we report the 1.78 Å resolution crystal structure of BacPelA in apo form. The enzyme has the characteristic right-handed β-helix fold of members of the polysaccharide lyase 1 family and shows overall structural similarity to them, but it displays some differences in the details of the secondary structure and Ca
-binding site. On the basis of the structure, 10 sites located in flexible regions and showing high B-factor and positive Δ
values were selected for mutation, aiming to improve the thermo-alkaline stability of the enzyme. Following site-directed saturation mutagenesis and screening, mutants A238C, R150G, and R216H showed an increase in the
value at pH 10.0 of 3.0 °C, 6.5 °C, and 7.0 °C, respectively, compared with the wild-type enzyme, interestingly accompanied by a 24.5%, 46.6%, and 61.9% increase in activity. The combined mutant R150G/R216H/A238C showed an 8.5 °C increase in the
value at pH 10.0, and an 86.1% increase in the specific activity at 60 °C, with approximately doubled catalytic efficiency, compared with the wild-type enzyme. Moreover, this mutant retained 86.2% activity after incubation in ramie degumming conditions (4 h, 60 °C, pH 10.0), compared with only 3.4% for wild-type BacPelA. The combined mutant increased the weight loss of ramie fibers in degumming by 30.2% compared with wild-type BacPelA. This work provides a thermo-alkaline stable, highly active pectate lyase with great potential for application in the textile industry, and also illustrates an effective strategy for rational design and improvement of pectate lyases.
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