Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 546
Filtrar
2.
Int J Radiat Biol ; : 1-9, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31692404

RESUMO

Purpose: Heavy-ion beams and γ-rays are popular physical mutagenesis to generate mutations in higher plants. It has been found that they show different mutation frequencies and spectrums of phenotype induction, however, the characteristics of heavy-ion beams on genetic polymorphism have not been clarified by comparing with γ-rays.Materials and methods: In the present study, seeds of Arabidopsis thaliana were exposed to carbon-ion beams (with linear energy transfer (LET) of 50 keV/µm) and γ-rays (with average LET of 0.2 keV/µm) irradiation. By using inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) analysis, the genetic polymorphism of both M1 and M3 plants were investigated, respectively.Results: Carbon-ion beams induced relatively higher polymorphism rate in both M1 and M3 generation than γ-rays: the polymorphism rates of M1 plants derived from carbon-ion beams irradiation are 12.87% (ISSR-C) and 9.01% (RAPD-C), while are 7.67% (ISSR-γ) and 1.45% (RAPD-γ) of plants derived from γ-rays. In M3 generation, the polymorphism rates of ISSR-C, RAPD-C, ISSR-γ, and RAPD-γ are 17.64%, 22.79%, 12.10%, and 2.82%, respectively.Conclusions: In summary, the exposure to carbon-ion beams and γ-rays lead to the change of genomic DNA of A. thaliana, which could be tested in M1 plants and M3 plants by ISSR and RAPD technology. So, both carbon-ion beams and γ-rays can induce variations of genetic polymorphisms in M1 plants and M3 plants. The genetic polymorphisms of M1 plants and M3 plants induced by carbon-ion beams are higher than γ-rays, indicating that heavy-ion beams irradiations mutation breeding is more advantageous than conventional ionizing radiations. Average molecular polymorphism of M1 plants is lower than M3 mutants, by nearly 4.77% (ISSR-C), 13.78% (RAPD-C), 4.43% (ISSR-γ), and 1.37% (RAPD-γ). We hope our study will provide basic information for understanding the effects of carbon-ion beams and γ-rays for plant mutation breeding.

3.
Sci Total Environ ; 700: 134999, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31739272

RESUMO

There is an urgent need to develop low-cost and effective adsorbents for enhanced removal of phosphate from contaminated waters. In this study, nanosized Zr(IV) oxide particles were immobilized on the amino modified corn staw (MCS) to fabricate a novel nanocomposite (Zr@MCS) with superior application capability. Compared with the widely used commercial anion exchangers in previous studies, the modified agricultural residue was empolyed as the host to avoid the high costs and secondary pollution in the preparation. Zr@MCS displayed remarkable selective removal of phosphate from water even in the presence of coexisting anions (Cl-, SO42-, NO3-) at high levels, as well as with a high adsorption capacity, fast adsorption kinetics and high availability in the wide range of pH 2-8 toward phosphate. The excellent adsorption performance of Zr@MCS is attributed to the synergistic effect of the electrostatic attraction of the quaternary ammonium groups fixed on the host skeleton and the specific adsorption of phosphate derived from the hydroxyl functional groups of Zr(IV) oxide. The exhausted Zr@MCS can be effectively regenerated by 5% NaOH-NaCl solution for sustainably utilized, and phosphorus in the desorption effluent could be recovered as high-quality struvite by a simple struvite recovery process. Furthermore, the considerable treatment volume for the synthetic solution and real wastewater in a fixed-bed flow system indicated that Zr@MCS is of great potential for phosphate removal in practice.

4.
Can J Cardiol ; 35(11): 1546-1556, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31679624

RESUMO

BACKGROUND: Endothelial progenitor cell (EPC) therapy has been suggested as a major breakthrough in the treatment of ischemic diseases. However, the molecular mechanism that underlies EPC functional regulation is still unclear. METHODS: We examined the angiogenic capacity of EPCs in a hindlimb ischemia model of wild-type and ClC-3 knockout mice. RESULTS: Mice lacking of ClC-3 exhibited reduced blood flow recovery and neovascularization in ischemic muscles 7 and 14 days after hind limb ischemia. Moreover, compared with wild-type EPCs, the hindlimb blood reperfusion in mice receiving ClC-3 knockout EPCs was significantly impaired, accompanied by reduced EPC homing and retention. In vitro, EPCs derived from ClC-3 knockout mice displayed impaired migratory, adhesive, and angiogenic activity. CXC chemokine receptor 4 (CXCR4) expression was significantly reduced in EPC from ClC-3 knockout mice compared with wild-type. Moreover, the expression and phosphorylation of Janus kinase 2 (JAK-2), a downstream signalling of CXCR4, was also reduced in ClC-3 knockout EPC, indicating that CXCR4/JAK-2 signalling is dysregulated by ClC-3 deficiency. Consistent with this assumption, the migratory capacity of wild-type EPCs was attenuated by either CXCR4 antagonist AMD3100 or JAK-2 inhibitor AG490. More importantly, the impaired migratory capacity of ClC-3 knockout EPCs was rescued by overexpression of CXCR4. CONCLUSIONS: ClC-3 plays a critical role in the angiogenic capacity of EPCs and EPC-mediated neovascularization of ischemic tissues. Disturbance of CXCR4/JAK-2 signalling may contribute to the functional impairment of ClC-3 deficient EPCs. Thus, ClC-3 may be a potential therapeutic target for modulating neovascularization in ischemic diseases.

5.
Colloids Surf B Biointerfaces ; : 110641, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31759778

RESUMO

Rapid hemostasis is crucial to saving the lives of traumatic patients in emergency medical treatment. To improve the hemostatic performance of the gelatin microspheres (GMs) in vivo and in vitro, in the study, porous gelatin microspheres (PGMs) were prepared through water-in-oil emulsion method combined with vacuum freeze-drying after cross-linking with glutaraldehyde and prefreeze in liquid nitrogen. Owing to the porous structure and rough surface, the obtained PGMs were effective to induce red blood cells aggregation and promote fibrin generation, which led to improved hemostatic potential than GMs in blood coagulation time, whole blood clotting rate, and the hemostatic efficiency of rabbit liver wound and ear vein cut models tests. The potent hemostatic effect of the PGMs could be attributed to the synergistic effects of the physiological blood coagulation activated by negatively charged surface and physical barriers reinforced by fibrin. Moreover, PGMs with high water absorption rate and porous structure showed better hemostatic performance than commercial hemostatic powder (chitosan hemostasis power and Yunnan Baiyao) in vitro and in vivo. Cytotoxicity tests with bone marrow mesenchymal stem cells of murine showed that PGMs with excellent cytocompatibility were conducive to cell proliferation. Therefore, it could be concluded that PGMs were more suitable for rapid hemostasis than GMs and had a great potential for hemostatic applications.

6.
Acta Biomater ; 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31760222

RESUMO

Natural and synthetic hydrogels have been widely investigated as biomaterial scaffolds to promote tissue repair and regeneration. Nevertheless, the scaffold alone is often insufficient to drive new tissue growth, instead requiring continuous delivery of therapeutics, such as proteins or other biomolecules that work in concert with structural support provided by the scaffold. However, because of the high-water content, hydrogels tend to be permeable and cause rapid release of the encapsulated drug, which could lead to serious complications from local overdose and may result in the significant waste of encapsulated therapeutic(s). To this end, we designed an oligonucleotide-functionalized hydrogel that can provide sustained and controlled delivery of therapeutics for up to 4 weeks. To prove this concept, we successfully achieved sustained release (for over 28 days) of model anti-Nogo receptor (anti-NgR) RNA aptamer from oligonucleotide-functionalized hyaluronic acid-based hydrogel by changing the complementarity between the short antisense sequences and the aptamer. Furthermore, the released aptamer successfully blocked neuro-inhibitory effects of myelin-derived inhibitors and promoted neurite outgrowth from rat dorsal root ganglia in vitro. Because antisense sequences can be designed to bind to proteins, peptides, and aptamer, our oligonucleotide-functionalized hydrogel offers a promising therapeutic delivery system to obtain controlled release (both bolus and sustained) of various therapeutics for the treatment of complex diseases and injury models, such as spinal cord injury. Statement of Significance Producing a therapeutic effect often requires the administration of multiple injections with high dosages. This regimen causes discomfort to the patient and raises cost of treatment. Additionally, systemic delivery of therapeutics often results in adverse effects; therefore, local delivery at the site of injury is desirable. Therefore, in this study, we designed an oligonucleotide-functionalized biomaterial platform using ssDNA oligonucleotides (immobile species) as antisense sequences to increase residence time and fine-tune the release of anti-nogo receptor aptamer (mobile species) for spinal cord injury application. Because antisense sequences can be designed to bind proteins, peptides, and aptamer, our hydrogel offers a promising delivery system to obtain controlled release of various therapeutics for the treatment of complex diseases and injury models.

7.
BMC Evol Biol ; 19(1): 203, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31694538

RESUMO

BACKGROUND: The flood of genomic data to help build and date the tree of life requires automation at several critical junctures, most importantly during sequence assembly and alignment. It is widely appreciated that automated alignment protocols can yield inaccuracies, but the relative impact of various sources error on phylogenomic analysis is not yet known. This study employs an updated mammal data set of 5162 coding loci sampled from 90 species to evaluate the effects of alignment uncertainty, substitution models, and fossil priors on gene tree, species tree, and divergence time estimation. Additionally, a novel coalescent likelihood ratio test is introduced for comparing competing species trees against a given set of gene trees. RESULTS: The aligned DNA sequences of 5162 loci from 90 species were trimmed and filtered using trimAL and two filtering protocols. The final dataset contains 4 sets of alignments - before trimming, after trimming, filtered by a recently proposed pipeline, and further filtered by comparing ML gene trees for each locus with the concatenation tree. Our analyses suggest that the average discordance among the coalescent trees is significantly smaller than that among the concatenation trees estimated from the 4 sets of alignments or with different substitution models. There is no significant difference among the divergence times estimated with different substitution models. However, the divergence dates estimated from the alignments after trimming are more recent than those estimated from the alignments before trimming. CONCLUSIONS: Our results highlight that alignment uncertainty of the updated mammal data set and the choice of substitution models have little impact on tree topologies yielded by coalescent methods for species tree estimation, whereas they are more influential on the trees made by concatenation. Given the choice of calibration scheme and clock models, divergence time estimates are robust to the choice of substitution models, but removing alignments deemed problematic by trimming algorithms can lead to more recent dates. Although the fossil prior is important in divergence time estimation, Bayesian estimates of divergence times in this data set are driven primarily by the sequence data.

8.
Gene ; : 144196, 2019 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-31669648

RESUMO

Accumulating evidence has indicated the important roles of circular RNAs (circRNAs) in different tumors. However, their detailed regulatory mechanisms in glioma are not fully understood. In this study, the functional role of a novel circRNA, circ-EZH2, was investigated by cell counting kit-8 (CCK-8), colony formation, flow cytometry, and transwell experiments. The regulatory mechanism of circ-EZH2 was explored by bioinformatics analysis, quantitative real-time PCR (qRT-PCR), Western blot and dual-luciferase reporter assay. We identified that circ-EZH2 was overexpressed in glioma tissues and cell lines. Further studies revealed that ectopic expression of circ-EZH2 significantly promoted cell growth, migration and invasion but inhibited cell apoptosis. By contrast, silencing of circ-EZH2 induced the opposite effects. Additionally, we found circ-EZH2 served as a miRNA sponge for miR-1265 to release its suppression on DDAH1 and CBX3. Rescue assays further revealed that the oncogenic function of circ-EZH2 was partly dependent on its modulation of DDAH1 and CBX3. Our study unraveled a novel molecular pathway in glioma and may provide a new perspective for the treatment of glioma.

9.
JMIR Mhealth Uhealth ; 7(11): e14452, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31682586

RESUMO

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a major public health burden. Self-management of diabetes including maintaining a healthy lifestyle is essential for glycemic control and to prevent diabetes complications. Mobile-based health data can play an important role in the forecasting of blood glucose levels for lifestyle management and control of T2DM. OBJECTIVE: The objective of this work was to dynamically forecast daily glucose levels in patients with T2DM based on their daily mobile health lifestyle data including diet, physical activity, weight, and glucose level from the day before. METHODS: We used data from 10 T2DM patients who were overweight or obese in a behavioral lifestyle intervention using mobile tools for daily monitoring of diet, physical activity, weight, and blood glucose over 6 months. We developed a deep learning model based on long short-term memory-based recurrent neural networks to forecast the next-day glucose levels in individual patients. The neural network used several layers of computational nodes to model how mobile health data (food intake including consumed calories, fat, and carbohydrates; exercise; and weight) were progressing from one day to another from noisy data. RESULTS: The model was validated based on a data set of 10 patients who had been monitored daily for over 6 months. The proposed deep learning model demonstrated considerable accuracy in predicting the next day glucose level based on Clark Error Grid and ±10% range of the actual values. CONCLUSIONS: Using machine learning methodologies may leverage mobile health lifestyle data to develop effective individualized prediction plans for T2DM management. However, predicting future glucose levels is challenging as glucose level is determined by multiple factors. Future study with more rigorous study design is warranted to better predict future glucose levels for T2DM management.

10.
Opt Express ; 27(21): 29639-29648, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31684221

RESUMO

Realization of the highly efficient hybrid atom-photon gates is vital to the quantum interface that integrates atoms and superconducting resonators. Here we propose a scheme to realize the hybrid state transfer and controlled-PHASE gate based on Raman chirped shortcut to adiabatic passage. The scheme is fast to protect the quantum state from the decoherence effects in the hybrid interface, as well as is robust due to the geometric phase. We show that this two-qubit gate is more resilient than the Raman pulse and Raman chirped adiabatic passage against the variations in the vacuum coupling strength and two-photon detuning. Its fast and robust features make it especially suitable for long-term storage and optical readout of superconducting qubits, and moreover, entanglement swapping between two disparate components.

11.
Int J Biol Macromol ; 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31726167

RESUMO

The occurrence of Maillard reaction in protein - polysaccharide coacervated microcapsules and its effects on microcapsule properties were investigated. Vitamin E microcapsules were prepared by soybean protein isolate - chitosan coacervation at 50 °C, 70 °C, or 90 °C for 12 h in the presence of maltose. Chromatic and furosine measurements revealed that Maillard reaction occurred in the microcapsules and was favored by high incubation temperatures. The three coacervation temperatures did not destroy the microcapsule structure, but improved the microencapsulation efficiency and microencapsulation yield instead. The microcapsules exhibited decreased aggregation and the increased absolute zeta potential and particle size were believed contribute to this improvement. Stability analysis demonstrated that the microcapsules possessed enhanced resistance to dissolution in water and improved storage stability than control microcapsules. It is concluded that coacervation at a temperature high enough to initiate Maillard reaction is a promising way to improve the physiochemical properties of protein - polysaccharide coacervated microcapsules.

12.
Se Pu ; 37(11): 1157-1161, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31642267

RESUMO

A method using ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of nine B vitamins in peptone. The samples were extracted with water. The analytes were separated on a Syncronis C18 column (100 mm×2.1 mm, 1.7 µm). The nine B vitamins were detected by ESI-MS/MS under the multiple reaction monitoring (MRM) mode, and the analysis was completed in 8 min. Quantification analysis was performed by using the external standard method. The correlation coefficients (R2) of the nine B vitamins in their linear ranges were greater than 0.999. The limits of detection were 0.09-1.67 µg/L. The relative standard deviations of the method were less than 3% (n=6). The mean recoveries of the nine B vitamins were 80.2%-103.9% at different spiked levels. The method is simple, accurate and sensitive, and is suitable for the determination of the nine B vitamins in peptone.


Assuntos
Peptonas/química , Complexo Vitamínico B/análise , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas em Tandem
13.
Proc Natl Acad Sci U S A ; 116(44): 22353-22358, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31611414

RESUMO

An Australian estuarine isolate of Penicillium sp. MST-MF667 yielded 3 tetrapeptides named the bilaids with an unusual alternating LDLD chirality. Given their resemblance to known short peptide opioid agonists, we elucidated that they were weak (K i low micromolar) µ-opioid agonists, which led to the design of bilorphin, a potent and selective µ-opioid receptor (MOPr) agonist (K i 1.1 nM). In sharp contrast to all-natural product opioid peptides that efficaciously recruit ß-arrestin, bilorphin is G protein biased, weakly phosphorylating the MOPr and marginally recruiting ß-arrestin, with no receptor internalization. Importantly, bilorphin exhibits a similar G protein bias to oliceridine, a small nonpeptide with improved overdose safety. Molecular dynamics simulations of bilorphin and the strongly arrestin-biased endomorphin-2 with the MOPr indicate distinct receptor interactions and receptor conformations that could underlie their large differences in bias. Whereas bilorphin is systemically inactive, a glycosylated analog, bilactorphin, is orally active with similar in vivo potency to morphine. Bilorphin is both a unique molecular tool that enhances understanding of MOPr biased signaling and a promising lead in the development of next generation analgesics.

14.
Opt Lett ; 44(19): 4801-4804, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31568446

RESUMO

We propose a controlled-PHASE gate for neutral atoms in which one of the qubit state components adiabatically evolves along the multiple-atom eigenstate formed by the chirped laser pulse coupling to Rydberg states and intrinsic dipole-dipole exchange interactions and, consequently, accumulates an interaction-induced geometric phase. The geometric Rydberg gate is not limited by an adiabatic condition, which is sped up by shortcuts to adiabaticity (STA). Analyses show that an STA scheme is more robust than a non-adiabatic case against the variations of control parameters and faster than an adiabatic case, which protects from the decay of Rydberg states. Furthermore, an intermediate value of dipole-dipole interaction strength is enough for our scheme.

15.
Rev Sci Instrum ; 90(9): 095102, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31575248

RESUMO

In this paper, we demonstrate the use of a surface condensation sensor board for characterizing interior space in a damp heat chamber. The sensor board is approximately 18 in. × 12 in. in dimension. A total of 324 sense electrodes are designed on the board. The uniform gap between the sense electrodes is 250 µm throughout the surface area of the board. First, the surface leakage current of the sensor board is characterized with other commercially available humidity sensors. The relationship of leakage current to humidity is determined. Surface leakage current is spatially measured inside the chamber, and localized condensation spots are identified at 85 °C/85%RH stress condition. The main goal of this article is to characterize interior space and identify less-risky locations prior to qualification of semiconductor components, optical subassemblies, and optical modules.

16.
J Food Sci ; 84(10): 2812-2819, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31546282

RESUMO

This study was aimed to assess the effect of membrane structure on the stability of peanut oil bodies extracted by enzyme-assisted extraction. The influence of pH, NaCl concentration, and temperature on the physicochemical properties of peanut oil bodies was characterized using ζ-potential and particle size. The results indicated that the peanut oil bodies had strong stability (ζ-potential, >20 mV) at pH values away from the isoelectric point (pH 4.8), at a low salt concentration (NaCl concentration, <10 mM), and in a certain temperature range (35 to 55 °C). The stable structure of the oil body was closely related to its structure. Phospholipids, along with membrane proteins, were major components of the oil body membrane. Therefore, the phospholipid composition and content were measured and the types of membrane proteins of the oil bodies were identified. The results showed that phosphatidylcholine and phosphatidylserine were major components of the oil body phospholipids. Two-dimensional electrophoresis showed that the oil bodies contained both intrinsic proteins and extrinsic proteins, which might play an important role in the stability of oil bodies during enzyme-assisted extraction processing.

17.
Artigo em Inglês | MEDLINE | ID: mdl-31520876

RESUMO

OBJECTIVES: To determine the risk factors for development of caesarean scar defect (CSD), compare the efficacy of transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) for CSD assessment, and investigate the association between CSD size and clinical symptoms. STUDY DESIGN: One hundred and eighty-nine women with CSD and 378 women without CSD with a history of caesarean section (CS) at the Obsterics and Gynaecology Hospital of Fudan University between January 2008 and February 2016 were enrolled. The potential risk factors for CSD were investigated using multivariate logistic regression analysis. TVS and MRI were performed for CSD measurements, including residual myometrial thickness, and depth, length and width of CSD. Associations between CSD size by TVS/MRI and symptoms were evaluated. RESULTS: CS time ≥85 min, peripartum fever or infection, and retroflexed uterus were risk factors for CSD, and age at last CS < 30 years, intraoperative blood loss <150 ml and double-layer closure were protective factors for CSD. Prolonged menstruation, dysmenorrhoea, chronic pelvic pain and infertility were the main clinical manifestations. Women with a larger CSD presented with more prolonged menstruation. Compared with TVS, measurements by MRI showed better prediction of the clinical symptoms of CSD. CONCLUSIONS: Various factors contribute to the development of CSD. Prevention of peripartum infection, reduction of CS time, reduction of blood loss and more careful uterine closure are needed to decrease the risk of developing CSD. MRI is a reliable method for the diagnosis and measurement of CSD, and can be utilized in clinical practice.

18.
Anal Chim Acta ; 1079: 171-179, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387708

RESUMO

Recent study proves that the combination of loop mediated isothermal nucleic acid amplification (LAMP) with one-step strand displacement (OSD) is of great help to improve the sequence specificity during genetic detection. However, because OSD is incapable of signal amplification, the signal-to-noise ratio or the observable signal change may be usually not significant enough to satisfy practical usage. With the purpose to overcome this challenge, herein a more advanced and practical sensing principle is developed with the OSD replaced by an amplifiable nucleic acid circuit, hybridization chain reaction (HCR). The very contagious norovirus (NoV) was employed as the model target. Compared with LAMP-OSD, the LAMP-HCR can detect as few as 30 copies of NoV gene in 2% fecal samples with significantly enlarged signal change and signal-to-background ratio. Therefore, more reliable detection is achieved. Moreover, due to the high compatibility of HCR, the final LAMP-HCR products can be flexibly transduced into different types of readouts, including fluorescence, flow cytometer (FCM) and even a personal glucose meter (PGM). This further enlarges the operating environments for the detection from hospital labs, bedsides, to potential off-the-shelf devices in local pharmacies. Especially when using FCM or PGM, with the assistance of magnetic beads (MBs), the detection shows even higher tolerance capability to complicated biological matrices.

19.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2267-2274, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418229

RESUMO

The variation of soil enzyme activity and relevance with soil nutrients was examined in multistable grazing alpine Kobresia grassland, including Gramineae-Kobresia humilis community, K. humilis community, K. pygmaea community at thickened stage, K. pygmaea community at cracked stage and forb-black soil type secondary bare land. The results showed that the vegetation coverage and aboveground biomass successively decreased with degenerative succession. The belowground biomass was the highest in the K. pygmaea community at thickened and cracked stages. The activities of soil sucrase, urease, cellulase, alkaline phosphatase and aryl sulfatase were higher at the surface soil layer (0-10 cm) than those at the subsurface soil layer (10-20 cm), while the pattern of chitinase activity was contrary. The activities of cellulase, alkaline phosphatase and aryl sulfatase were the highest in the Gramineae-K. humilis community and the lowest at the forb-black soil type secondary bare land, and they slightly increased during the thickened stage of K. pygmaea community. Chitinase activity was relatively high at the middle three stages, while urease and sucrase activity had an obvious increase in the forb-black soil type secondary bare land. Soil moisture, ammonium, alkali-hydrolyzable nitrogen, total nitrogen, total carbon and organic carbon successively decreased with degenerative succession, whereas the concentrations of nitrate and available phosphorus increased at the latter two succession stages. The activities of the other enzymes, except for chitinase, were significantly positively correlated with the soil available phosphorus, ammonium, alkali-hydrolyzed nitrogen, total carbon, and organic carbon, and negatively correlated with soil pH. The activities of cellulose, alkaline phosphatase and aryl sulfatase were significantly positively correlated with soil moisture and total nitrogen. The main factors affecting soil enzyme activity were available phosphorus and ammonium. Soil enzymes showed different evolutionary trends influenced by grazing degradation succession in the alpine grassland, with a synergistic effect with soil nut-rients. Moreover, severely degraded extreme environments may stimulate soil enzyme activities related to nitrogen and carbon transformation.


Assuntos
Enzimas/análise , Pradaria , Solo , Biomassa , Carbono , China , Nitrogênio , Nutrientes
20.
Oncogene ; 38(46): 7113-7132, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31417182

RESUMO

Collective invasion into adjacent tissue is a hallmark of luminal breast cancer, and ~20% of these cases eventually undergo metastasis. How less aggressive luminal-like breast cancer transitions to invasive cancer remains unclear. Our study revealed that CD44hi cancer cells are the leading subpopulation in collectively invading luminal cancer cells and efficiently promote the collective invasion of CD44lo/follower cells. The CD44hi/leader subpopulation showed a specific gene signature of various hybrid epithelial/mesenchymal genes and key functional coregulators of collective invasion, which was distinct from that of CD44lo/follower cells. However, the CD44hi/leader cells, which showed a partial epithelial-mesenchymal transition (EMT) phenotype, readily switched to the CD44lo phenotype along with collective migration and vice versa; this phenomenon was spontaneous and sensitive to the tumor microenvironment. The CD44lo-to-CD44hi conversion was accompanied by a shift in CD44s to CD44v but not a conversion of non-cancer stem cells to cancer stem cells (CSCs). Therefore, the CD44hi leader cells, as currently identified, are not a stable subpopulation in breast tumors. This plasticity and ability to generate CD44hi carcinoma cells with enhanced migratory and invasive behavior might be responsible for the transition from in situ to invasive behavior of luminal-type breast cancer.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA