The pollen receptor kinase LePRK2 mediates growth-promoting signals and positively regulates pollen germination and tube growth

In flowering plants, the process of pollen germination and tube growth is required for successful fertilization. A pollen receptor kinase from tomato (Solanum lycopersicum), LePRK2, has been implicated in signaling during pollen germination and tube growth as well as in mediating pollen (tube)-pistil communication. Here we show that reduced expression of LePRK2 affects four aspects of pollen germination and tube growth. First, the percentage of pollen that germinates is reduced, and the time window for competence to germinate is also shorter. Second, the pollen tube growth rate is reduced both in vitro and in the pistil. Third, tip-localized superoxide production by pollen tubes cannot be increased by exogenous calcium ions. Fourth, pollen tubes have defects in responses to style extract component (STIL), an extracellular growth-promoting signal from the pistil. Pollen tubes transiently overexpressing LePRK2-fluorescent protein fusions had slightly wider tips, whereas pollen tubes coexpressing LePRK2 and its cytoplasmic partner protein KPP (a Rop-GEF) had much wider tips. Together these results show that LePRK2 positively regulates pollen germination and tube growth and is involved in transducing responses to extracellular growth-promoting signals.Fil: Zhang, Dong. Chinese Academy of Sciences; República de ChinaFil: Wengier, Diego Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; Argentina. University of California at Berkeley; Estados UnidosFil: Shuai, Bin. University of California at Berkeley; Estados UnidosFil: Gui, Cai Ping. Chinese Academy of Sciences; República de ChinaFil: Muschietti, Jorge Prometeo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; ArgentinaFil: McCormick, Sheila. University of California at Berkeley; Estados UnidosFil: Tang, Wei Hua. Chinese Academy of Sciences; República de China. University of California at Berkeley; Estados Unido

A new model for the double well potential

A new model for the double well potential is presented in the paper. In the new potential, the exchanging rate could be easily calculated by the perturbation method in supersymmetric quantum mechanics. It gives good results whether the barrier is high or sallow. The new model have many merits and may be used in the double well problem.Comment: 3pages, 3figure

Experimental study on fatigue performance of adhesively bonded anchorage system for CFRP tendons

This study is concerned with the fatigue performance of adhesively bonded anchorage for carbon fiber reinforced polymer (CFRP) tendons subjected to cyclic loading. Series of monotonous and cyclic experiments under different stress amplitudes and loading frequencies were carried out in order to investigate the mechanical performance of bonded anchorage systems for CFRP tendons and to study the influence of cyclic loading on the anchoring performance. The fatigue damage and the relationships between damage, loading frequency and interfacial temperature rise of anchorage systems were analyzed. The results show that cyclic tension-tension loading is instrumental in enhancing the synergistic interaction between the anchorage components and it also stabilizes the entire anchorage system performance provided that the stress amplitude is kept lower than 10% of the ultimate tensile capacity of the anchorage systems and the maximum stress is less than 50% of the ultimate capacity of the anchorage system. The loading frequency influences significantly the temperature variation in the anchorage system. A high loading frequency may result in a sharp temperature rise at the early-stage and mid-stage of cyclic tension-tension loading, followed by a rather stable late stage. This phenomenon of temperature rise during fatigue tests may indicate the extent of fatigue damage in the anchorage system

Limonoids and triterpenoids from the twigs and leaves of Dysoxylum hainanense

Four new limonoids, dysohainanins A–D (1–4), and two new triterpenoids, dysohainanins E and F (5 and 6), together with seven known ones were isolated from the twigs and leaves of Dysoxylum hainanense Merr. The structures of the new compounds were determined by a variety of spectroscopic methods. The cytotoxic activities of these compounds were evaluated, and the known compound ent-19-nor-4,16,18-trihydroxy-8(14)-pomaren-15-one (13) showed in vitro cytotoxicity against HL-60, A-549, MCF-7, and SW480 cells, with IC(50) values of 24.3, 28.1, 30.7, and 22.5 µM, respectively. Compounds 2 and 3 were tested their insecticidal activities using brine shrimp and both of them were inactive. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s13659-011-0030-8 and is accessible for authorized users

Overexpression of the Tomato Pollen Receptor Kinase LePRK1 Rewires Pollen Tube Growth to a Blebbing Mode

The tubular growth of a pollen tube cell is crucial for the sexual reproduction of flowering plants. LePRK1 is a pollen-specific and plasma membrane–localized receptor-like kinase from tomato (Solanum lycopersicum). LePRK1 interacts with another receptor, LePRK2, and with KINASE PARTNER PROTEIN (KPP), a Rop guanine nucleotide exchange factor. Here, we show that pollen tubes overexpressing LePRK1 or a truncated LePRK1 lacking its extracellular domain (LePRK1ΔECD) have enlarged tips but also extend their leading edges by producing “blebs.” Coexpression of LePRK1 and tomato PLIM2a, an actin bundling protein that interacts with KPP in a Ca2+-responsive manner, suppressed these LePRK1 overexpression phenotypes, whereas pollen tubes coexpressing KPP, LePRK1, and PLIM2a resumed the blebbing growth mode. We conclude that overexpression of LePRK1 or LePRK1ΔECD rewires pollen tube growth to a blebbing mode, through KPP- and PLIM2a-mediated bundling of actin filaments from tip plasma membranes. Arabidopsis thaliana pollen tubes expressing LePRK1ΔECD also grew by blebbing. Our results exposed a hidden capability of the pollen tube cell: upon overexpression of a single membrane-localized molecule, LePRK1 or LePRK1ΔECD, it can switch to an alternative mechanism for extension of the leading edge that is analogous to the blebbing growth mode reported for Dictyostelium and for Drosophila melanogaster stem cells.Fil: Gui, Cai Ping. Chinese Academy of Sciences; República de ChinaFil: Dong, Xin. Chinese Academy of Sciences; República de ChinaFil: Liu, Hai Kuan. Chinese Academy of Sciences; República de ChinaFil: Huang, Wei Jie. Chinese Academy of Sciences; República de ChinaFil: Zhang, Dong. Chinese Academy of Sciences; República de ChinaFil: Wang, Shu Jie. Chinese Academy of Sciences; República de ChinaFil: Barberini, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Gao, Xiao Yan. Chinese Academy of Sciences; República de ChinaFil: Muschietti, Jorge Prometeo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: McCormick, Sheila. University of California at Berkeley; Estados UnidosFil: Tang, Wei Hua. Chinese Academy of Sciences; República de China. University of California at Berkeley; Estados Unido

RbCa2Nb3O10 from X-ray powder data

Rubidium dicalcium triniobate(V), RbCa2Nb3O10, has been synthesized by solid-state reaction and its crystal structure refined from X-ray powder diffraction data using Rietveld analysis. The compound is a three-layer perovskite Dion–Jacobson phase with the perovskite-like slabs derived by termination of the three-dimensional CaNbO3 perovskite structure along the ab plane. The rubidium ions (4/mmm symmetry) are located in the inter­stitial space

Performance optimisation of room temperature magnetic refrigerator with layered/multi-material microchannel regenerators

Abstract A hybrid numerical model of the magnetic refrigerator with multi-material microchannel regenerator has been developed. The magnetocaloric effect was implemented using instantaneous temperature rise/drop (discrete method). Two pipe-in-pipe heat exchangers at two ends of the regenerator were treated using ε-NTU method. The commercially available compounds of LaFe 13-xy Co x Si y as well as hypothetical compounds of Gadolinium were considered as the magnetocaloric materials Optimised Curie temperatures difference of two consecutive MCMs is found in a given range. Influence of hot end temperature on the cooling capacity is investigated

Lipopolysaccharide Stimulated the Migration of NIH3T3 Cells Through a Positive Feedback Between β-Catenin and COX-2

How β-catenin/COX-2 contribute to inflammation-induced fibroblasts migration remains poorly understood. Therefore, in this study, lipopolysaccharide (LPS) was used as a stimulus to accelerate the migration of NIH3T3 cells, which mimicked the tissue repair process. LPS treatment increased the cell migration in concentration-and time-dependent manner. And NS398, a COX-2 inhibitor, inhibited LPS-induced NIH3T3 cells migration. DKK-1, an antagonist of the Wnt/β-catenin signaling, also inhibited that migration. However, TWS119, an inducer of β-catenin via GSK-3β, increased the cell migration. LPS or TWS119 treatment increased COX-2, β-catenin, TGF-β1, and HMGB-1 expressions, and that could be attenuated by NS398 or DKK-1 addition. LPS induced the PGE2 production, and PGE2 increased the expression and nuclear translocation of β-catenin, while EP2 blocker, AH6809, alleviated those effects. TWS119 increased the luciferase activity in the COX-2 promoter. In conclusion, LPS stimulated the NIH3T3 fibroblasts migration through a positive feedback between β-catenin and COX-2, in which PGE2, EP2, TGF-β1, and HMGB-1 played as signal molecules

Multidrug resistance-selective antiproliferative activity of Piper amide alkaloids and synthetic analogues

Twenty-five amide alkaloids (1–25) from Piper boehmeriifolium and 10 synthetic amide alkaloid derivatives (39–48) were evaluated for antiproliferative activity against eight human tumor cell lines, including chemosensitive and multidrug-resistant (MDR) cell lines. The results suggested tumor type-selectivity. 1-[7-(3,4,5-Trimethoxyphenyl)heptanoyl]piperidine (46) exhibited the best inhibitory activity (IC50 = 4.94 µM) against the P-glycoprotein (P-gp)-overexpressing KBvin MDR sub-line, while it and all other tested compounds, except 9, were inactive (IC50 >40 µM) against MDA-MB-231 and SK-BR-3. Structure-activity relationships (SARs) indicated that (i) 3,4,5-trimethoxy phenyl substitution is critical for selectivity against KBvin, (ii) the 4-methoxy group in this pattern is crucial for antiproliferative activity, (iii) double bonds in the side chain are not needed for activity, and (iv), in arylalkenylacyl amide alkaloids, replacement of an isobutylamino group with pyrrolidin-1-yl or piperidin-1-yl significantly improved activity. Further study on Piper amides is warranted, particularly whether side chain length affects the ability to overcome the MDR cancer phenotype

The addition of a pH-sensitive gel improves microemulsion stability for the targeted removal of colonic ammonia

<p>Abstract</p> <p>Background</p> <p>We prepared an oral W/O microemulsion for the removal of colonic ammonia (ME-RCA). The effect of this microemulsion was influenced by the digestion process in the gastrointestinal tract. In this paper, we aim to show that stability was improved by using a microemulsion-based gel for the removal of colonic ammonia (MBG-RCA).</p> <p>Methods</p> <p>MBG-RCA was prepared by adding sodium alginate to the ME-RCA. MBG-RCA and ME-RCA were passed through a simulated gastrointestinal environment, and the amount of colonic ammonia present was then determined by titration with a standard solution of hydrochloric acid. The pH of the gastrointestinal fluid was measured using a pH test paper and the size and form of the microemulsions were examined under the microscope. 18 healthy rats were randomly divided into three groups, fasted for 24 hours and allowed to drink normally. Three-way pipes were placed at the gastroduodenal junction in Group I, and at the terminal ileum in Group II. After the intragastric administration of ME-RCA, the stomach contents in Group I, the effluent from the terminal ileum in Group II and discharge from the anus in Group III were collected. The pH values of the gastrointestinal juice were measured by the pH test paper and those of the colon were determined by a universal indicator. These animal experiments were also used to test the effect of MBG-RCA.</p> <p>Results</p> <p>MBG-RCA showed a better removal rate of artificial colonic ammonia than ME-RCA (P < 0.05). The decrease in pH value of the artificial small intestinal fluid due to ME-RCA did not occur when MBG-RCA was used. In the simulated gastrointestinal process, MBG-RCA maintained greater stability and released the emulsion (ME-RCA) in the colonic fluid. In the gastrointestinal tract of normal SD rats, ME-RCA decreased in size and lost its stable form after entering the small intestine, while MBG-RCA remained stable and intact emulsion-drops were observed from the anus. Neither substance had any effect on the pH of the stomach or colon of normal rats (partly because normal rats were fasted for 24 hours and allowed to drink normally, which resulted in a low level of ammonia production in the colon). Unlike ME-RCA, MBG-RCA did not reduce the pH of the small intestine.</p> <p>Conclusions</p> <p>MBG-RCA was more stable in the gastrointestinal tract and more effective at removing colonic ammonia when a higher concentration of ammonia was present. This made it possible to achieve the targeted removal of colonic ammonia and is a promising method to prevent hepatic encephalopathy (HE) in future studies.</p