Binding of DNA by a dinitro-diester calix[4]arene: denaturation and condensation of DNA

A study of a dinitro-diester calix[4]arene (5,17-(3-nitrobenzylideneamino)-11,23-di-tert-butyl- 25,27-diethoxycarbonyl methyleneoxy-26,28-dihydroxycalix[4]arene) interaction with calf-thymus DNA was carried out using several techniques. The measurements were done at various molar ratios X=[calixarene]/[DNA]. Results show diverse changes in the DNA conformation depending on the X value. Thus, at low macrocycle concentration, the calixarene binds to the polynucleotide. This interaction, mainly in groove mode, weakens the hydrogen bonds between the base pairs of the helix inducing the denaturation of the double strands, as well as the condensation of the macromolecule, from an extended coil state to a globular state. An opposite effect is observed at X molar ratios higher than 0.07. The de-condensation of DNA happens, that is, the transition from a compact state to a more extended conformation, probably due to the stacking of calixarene molecules in the solution. Results also show the importance of making a proper choice of the system under consideration

A Novel Communication Platform to Enable the Collaboration of Autonomous Underwater Vehicles

Abstract -A novel communication platform is introduced to enable the collaboration of a set of Autonomous Underwater Vehicles (AUV´

Carbon and nitrogen limitation increase chitosan antifungal activity in Neurospora crassa and fungal human pathogens

Chitosan permeabilizes plasma membrane and kills sensitive filamentous fungi and yeast. Membrane fluidity and cell energy determine chitosan sensitivity in fungi. A five-fold reduction of both glucose (main carbon (C) source) and nitrogen (N) increased 2-fold Neurospora crassa sensitivity to chitosan. We linked this increase with production of intracellular reactive oxygen species (ROS) and plasma membrane permeabilization. Releasing N. crassa from nutrient limitation reduced chitosan antifungal activity in spite of high ROS intracellular levels. With lactate instead of glucose, C and N limitation increased N. crassa sensitivity to chitosan further (4-fold) than what glucose did. Nutrient limitation also increased sensitivity of filamentous fungi and yeast human pathogens to chitosan. For Fusarium proliferatum, lowering 100-fold C and N content in the growth medium, increased 16-fold chitosan sensitivity. Similar results were found for Candida spp. (including fluconazole resistant strains) and Cryptococcus spp. Severe C and N limitation increased chitosan antifungal activity for all pathogens tested. Chitosan at 100 μg ml-1 was lethal for most fungal human pathogens tested but non-toxic to HEK293 and COS7 mammalian cell lines. Besides, chitosan increased 90% survival of Galleria mellonella larvae infected with C. albicans. These results are of paramount for developing chitosan as antifungal.This work was supported by Grants from the Spanish Ministries of Economy and Competitiveness (AGL 2011-29297/AGR) and (BFU 2010-16548)

Chitosan inhibits septin‐mediated plant infection by the rice blast fungus Magnaporthe oryzae in a protein kinase C and Nox1 NADPH oxidase‐dependent manner

Summary Chitosan is a partially deacetylated linear polysaccharide composed of β‐1,4‐linked units of d‐glucosamine and N‐acetyl glucosamine. As well as a structural component of fungal cell walls, chitosan is a potent antifungal agent. However, the mode of action of chitosan is poorly understood. Here, we report that chitosan is effective for control of rice blast disease. Chitosan application impairs growth of the blast fungus Magnaporthe oryzae and has a pronounced effect on appressorium‐mediated plant infection. Chitosan inhibits septin‐mediated F‐actin remodelling at the appressorium pore, thereby preventing repolarization of the infection cell. Chitosan causes plasma membrane permeabilization of M. oryzae and affects NADPH oxidase‐dependent synthesis of reactive oxygen species, essential for septin ring formation and fungal pathogenicity. We further show that toxicity of chitosan to M. oryzae requires the protein kinase C‐dependent cell wall integrity pathway, the Mps1 mitogen‐activated protein kinase and the Nox1 NADPH oxidase. A conditionally lethal, analogue (PP1)‐sensitive mutant of Pkc1 is partially remediated for growth in the presence of chitosan, while ∆nox1 mutants increase their glucan : chitin cell wall ratio, rendering them resistant to chitosan. Taken together, our data show that chitosan is a potent fungicide which requires the cell integrity pathway, disrupts plasma membrane function and inhibits septin‐mediated plant infection. </jats:p

Beyond Prejudice as Simple Antipathy: Hostile and Benevolent Sexism Across Cultures

The authors argue that complementary hostile and benevolent componen:s of sexism exist ac ro.ss cultures. Male dominance creates hostile sexism (HS). but men's dependence on women fosters benevolent sexism (BS)-subjectively positive attitudes that put women on a pedestal but reinforce their subordination. Research with 15,000 men and women in 19 nations showed that (a) HS and BS are coherenl constructs th at correlate positively across nations, but (b) HS predicts the ascription of negative and BS the ascription of positive traits to women, (c) relative to men, women are more likely to reject HS than BS. especially when overall levels of sexism in a culture are high, and (d) national averages on BS and HS predict gender inequal ity across nations. These results challenge prevailing notions of prejudice as an antipathy in that BS (an affectionate, patronizing ideology) reflects inequality and is a cross-culturally pervasive complement to HS