The bacterium Caulobacter crescentus secretes an adhesive polysaccharide called holdfast, which is the known strongest underwater adhesive in nature. The deacetylase encoded by hfs (holdfast ...synthesis) H gene is a key factor affecting the adhesion of holdfast. Its structure and function are not yet clear, and whether other polysaccharide deacetylases exist in C. crescentus is still unknown. The screening of both HfsH and its structural analogue as well as their purification from the artificial expression products of Escherichia coli is the first step to clarify these questions. Here, we determined the conserved domains of HfsH via sequence alignment among carbohydrate esterase family 4 enzymes and screened out its structural analogue (CC_2574) in C. crescentus. The recombinant HfsH and CC_2574 were effectively expressed in E. coli. Both of them were purified by chromatography from their corresponding productions in E. coli and were then functionally analyzed. The results indicated that a high deacetylase activity (61.8 U/mg) was observed in recombinant HfsH but not in CC_2574, which suggesting that HfsH might be the irreplaceable gene mediating adhesion of holdfast in C. crescentus. Moreover, the divalent metal ions Zn2+, Mg2+, and Mn2+ could promote the activity of recombinant HfsH at the concentration from 0.05 to 1 mM, but inhibit its activity when the concentration exceeds 1 mM. In sum, our study first realized the artificial production of polysaccharide deacetylase HfsH and its structural analogue, and further explored their functions, both of which laid the foundation for the development of new adhesive materials.
Calcium signal plays an important role in a variety of cancer cell metabolism, but knowledge on its role in head and neck squamous cell carcinoma (HNSCC) is limited. Store-operated calcium entry ...(SOCE) is the principal Ca2+ entry mechanism that maintains calcium concentration and produces calcium signal in non-excitable cells. SOCE is triggered by stromal interaction molecule 1 (STIM1), which is located in endoplasmic reticulum (ER) as Ca2+ sensor. Although, many studies demonstrated that STIM1 and SOCE play important functions in the regulation of many cancer progressions, their clinical relevance in HNSCC remains unclear. In this study, STIM1 expression levels notably increased in 89% HNSCC tissues compared with those in adjacent normal tissues. Meanwhile, this overexpression was close associated with tumor size but not with neck lymph node metastasis. Thus, this study mainly focuses on STIM1 function in HNSCC tumor growth. Three HNSCC cell lines, namely, TSCCA (oral cancer cell line) and Hep2 (laryngeal cell line) with high STIM1 expression levels and Tb3.1 (oral cancer cell line) with STIM1 expression level lower than previous two cell lines, were selected for in vitro study. Downregulated STIM1 expression levels in TSCCA and Hep2 arrested cells in G0/G1 stages, promoted cell apoptosis, and inhibited cell proliferation. By contrast, upregulated STIM1 expression in Tb3.1 inhibited cell apoptosis and promoted cell proliferation. Induced by thapsigargin (TG), ER stress was amplified when STIM1 expression was downregulated but was attenuated as STIM1 expression was upregulated. Furthermore, TSCCA cell xenograft models confirmed that STIM1 could promote HNSCC tumor growth in vivo. The present study provides new insight into HNSCC molecular mechanism and potential therapeutic target through targeting SOCE-dependent process. However, whether STIM1 participates in HNSCC metastasis requires further study.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
To characterize a recombinant isomerase that can catalyze the isomerization of sucrose into isomaltulose and investigate its application for the enzymatic production of isomaltulose.
...Results
A sucrose isomerase gene from
Erwinia sp
. Ejp617 was synthesized and expressed in
Escherichia coli
BL21(DE3). The enzymatic characterization revealed that the optimal pH and temperature of the purified sucrose isomerase were 6.0 and 40 °C, respectively. The enzyme activity was slightly activated by Mn
2+
and Mg
2+
, but partially inhibited by Ca
2+
, Ba
2+
, Cu
2+
, Zn
2+
and EDTA. The kinetic parameters of
K
m
and
V
max
for sucrose were 69.28 mM and 118.87 U/mg, respectively. The time course showed that 240.9 g/L of isomaltulose was produced from 300 g/L of sucrose, and the yield reached 80.3% after bioreaction for 180 min.
Conclusions
This recombinant enzyme showed excellent capability for biotransforming sucrose to isomaltulose at the substrate concentration of 300 g/L. Further investigations should be carried out focusing on selection of suitable heterologous expression system with the aim to improve its expression level.
Abstract Polar materials, with intrinsic polarization effects, present significant potential for photo(electro)catalysis. However, the available natural polar materials in this field are quite ...scarce, due to the requisite structural non‐centrosymmetry. Defect engineering emerges as a promising avenue for tuning material symmetry, yet achieving the transition from centrosymmetric to non‐centrosymmetric structures and optimizing associated polarization effects remains challenging. This study demonstrates symmetry breaking in centrosymmetric 3R‐delafossite AgFeO 2 through ordered oxygen defects introduction, yielding substantial macroscopic polarization. The transition is achieved via annealing post‐treatment of co‐precipitation‐hydrothermal AgFeO 2 samples, with precision in oxygen defects control by tailoring annealing conditions. Experimental characterizations reveal ordered interstitial oxygen and disordered oxygen vacancies. Density functional theory calculations indicate a higher propensity for the formation of disordered oxygen vacancies compared to ordered ones, while ordered interstitial oxygen is more easily formed than its disordered counterpart. Resultant macroscopic polarization enhances photoelectrochemical performance, with photocurrent density increasing from 0.79 to 2.95 µA cm −2 . Coupling macroscopic and spin polarization via external electric and magnetic fields further enhances photocurrent density (≈18.44 µA cm −2 ). These findings provide reference cases and strategies for applying polarization effects in photo(electro)catalytic technology.
Many long non-coding RNAs (lncRNAs) have been identified in several types of human pituitary adenomas and normal anterior pituitary, some of which are involved in the pathogenesis of pituitary ...adenomas. However, a systematic analysis of lncRNAs expressed at different developmental stages of normal pituitary, particularly in rats, has not been performed. Therefore, we contrasted two cDNA libraries of immature (D15) and mature (D120) anterior pituitary in rat that were sequenced on an Illumina HiSeq Xten platform, and a total of 29,568,806,352 clean reads were identified. Notably, 7039 lncRNA transcripts corresponded to 4442 lncRNA genes, and 1181 lncRNA transcripts were significantly differentially expressed in D15 and D120. In addition, 6839 protein-coding genes (<100 kb upstream and downstream) were the nearest neighbors of 4074 lncRNA genes. An interaction network of lncRNAs and the follicle-stimulating hormone beta-subunit (FSHb) gene was constructed using the lncRNATargets platform, and three novel lncRNAs were obtained. Furthermore, we detected the expression of the novel lncRNAs and ten highly expressed lncRNAs that were randomly selected through quantitative PCR (qPCR). The rat anterior pituitary lncRNA content identified in this study provides a more in-depth understanding of the roles of these lncRNAs in hormone and reproduction development and regulation in mammals.
Graphene nanoribbons (GNRs) are promising in nanoelectronics for their quasi‐1D structures with tunable bandgaps. The methods for controllable fabrication of high‐quality GNRs are still limited. Here ...a way to generate sub‐5‐nm GNRs by annealing single‐walled carbon nanotubes (SWCNTs) on Cu(111) is demonstrated. The structural evolution process is characterized by low‐temperature scanning tunneling microscopy. Substrate‐dependent measurements on Au(111) and Ru(0001) reveal that the intermediate strong SWCNT‐surface interaction plays a pivotal role in the formation of GNRs.
A novel approach is reported to facilely prepare graphene nanoribbons (GNRs) through the simple annealing of single‐walled carbon nanotubes (SWCNTs) on Cu(111). The surface‐catalyzed unzipping of SWCNTs occurs along a longitudinal line which directly contacts with Cu(111), affording straight GNRs. The structural evolution process is characterized by low‐temperature scanning tunneling microscopy with atom resolution.
Hexi Corridor is one of the most important base of vegetable producing areas in China. Livestock manure (LM) applied to agricultural field could lead to soil heavy metal (HM) pollution. Previous ...studies have focused on HM pollution following LM application in acidic polluted soils; however, fewer studies have been conducted in alkaline unpolluted soils. A 4-year field vegetable production experiment was conducted using pig manure (PM) and chicken manure (CM) at five application rates (0, 15, 30, 45, and 60 t ha
) to elucidate potential risks of HMs in an alkaline unpolluted soil in the Hexi Corridor oasis agricultural area and HM uptake by Chinese cabbage. The results showed that LM application caused a significant build-up of Cu, Zn, Pb, Cd, and Ni content in topsoil by 30.6-99.7%, 11.4-51.7%, 1.4-31.3%, 5.6-44.9%, 14%-40.8%, respectively. The Cd, Cu, Zn could potentially exceed the soil threshold in next 8-65 years after 15-60 t ha
LM application. Under LM treatment, the soil DTPA-extractable Cu, Zn, Fe, the acid-extractable fraction of Cu, Zn, Fe, Cd, Ni, and the Oxidable fraction of Cu, Zn, Fe, Mn, Cd, Ni significantly increased, but the DTPA-extractable Pb, Cd, the acid-extractable fraction of Pb, and the reducible fraction of Cd significantly decreased. Cu and Zn could migrate to the deeper soil and relatively increase in DTPA-extracted Cu, Zn were found in 20-40 cm soil depth after LM application. The pH and SOM could influence the bioavailability of HMs in soil. The bioaccumulation factor and transfer factor (TF) values were <1 except Mn (TF > 1). HMs in leaf did not approach the threshold for HM toxicity due to the "dilution effect". Recommend the type of manure was the PM and the annual PM application rate was 30 t ha
to ensure a 20-year period of clean production in alkaline unpolluted Fluvo-aqiuc vegetable soils.
The nerves were exposed from the front side of the axillary region or at the quadrilateral foramen from the back side of the axillary region Figure 1. Because these surgical incisions were in the ...flexible upper arm, the anterior approach could be completed with shoulder abduction, and the posterior approach could be completed with shoulder flexion and adduction, without changing patient position. ...the receptor nerves and their branches were assessed with compound muscle action potential (CMAP) with the parameters of 3.0 mA, three times for average Supplementary Figure 3, http://links.lww.com/CM9/A399. ...the CMAP test of deltoid muscle indicated that the posterior part was innervated mainly by the posterior branches of the axillary nerve Supplementary Table 2, http://links.lww.com/CM9/A399. ...the ulnar nerve was transferred to the posterior branches of axillary nerve, innervating the posterior deltoid.
The present communication reports a novel strategy to fabricate reversible shape‐memory polymer that operates without the aid of external force on the basis of a two‐phase structure design. The ...proof‐of‐concept material, crosslinked styrene‐butadiene‐styrene block copolymer (SBS, dispersed phase)/polycaprolactone‐based polyurethane (PU, continuous phase) blend, possesses a closely connected microphase separation structure. That is, SBS phases are chemically bonded to crosslinked PU by means of a single crosslinking agent and two‐step crosslinking process for increasing integrity of the system. Miscibility between components in the blend is no longer critical by taking advantage of the reactive blending technique. It is found that a suitable programming leads to compressed SBS, which serves as internal expansion stress provider as a result. The desired two‐way shape‐memory effect is realized by the joint action of the temperature‐induced reversible opposite directional deformabilities of the crystalline phase of PU and compressed SBS, accompanying melting and orientated recrystallization of the former. Owing to the broadness of material selection and manufacturing convenience, the proposed approach opens an avenue toward mass production and application of the smart polymer.
A reversible shape‐memory polymer is prepared, simply by reactive blending of semicrystalline polymer and elastomer. Temperature‐induced reversible shrinkage and extension of the components leads to a reversible shape‐memory effect of the programmed polymer blend without the intervention of external stress. The proposed approach is easy to be popularized due to the broad scope of raw materials and convenient procedures of material preparation.
► Sargassum patens C. Agardh was converted to bio-oil through hydrothermal liquefaction. ► A modified reactor was used for accurate reaction time. ► A maximum yield of 32.1±0.2wt.% bio-oil was ...obtained. ► The higher heating value of the bio-oil was 27.1MJ/kg.
The marine brown alga, Sargassum patens C. Agardh, floating on the Yellow Sea, was collected and converted to bio-oil through hydrothermal liquefaction with a modified reactor. A maximum yield of 32.1±0.2wt.% bio-oil was obtained after 15min at 340°C, at a feedstock concentration of 15g biomass/150ml water, without using a catalyst. The bio-oil had a heating value of 27.1MJ/kg and contained water, lipid, alcohol, phenol, esters, ethers and aromatic compounds. The solid residue obtained had a high ash and oxygen content. The results suggest that S. patens C. Agardh has potential as biomass feedstock for fuel and chemical products.
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