Search results for "Behavior"

Orbitally induced limestone/marlstone rhythms in the Albian—Cenomanian Cismon section (Venetian region, northern Italy): Sedimentology, calcareous an…

1996

Abstract A multidisciplinary study of the upper Albian—Cenomanian portion of the Cismon section (Venetian region, northern Italy) was undertaken in order to characterize the cyclic alternations of carbonate-rich and carbonate-poor layers and to investigate their possible origin and cyclic patterns. Limestone semicouplets are characterized by abundant radiolarians and micarbs (micron-sized calcitic fragments), common planktonic foraminifera, strong bioturbation, good oxygenation as expressed by the Mn* and V/(V+Ni) parameters, high Si/Al ratio, low K/Al, in the absence of pyrite and organic matter. The marlstone semicouplets are, on the contrary, frequently laminated, rich in pyrite and orga…

Novel host-specific iron acquisition system in the zoonotic pathogenVibrio vulnificus

2015

Summary Vibrio vulnificus is a marine bacterium associated with human and fish (mainly farmed eels) diseases globally known as vibriosis. The ability to infect and overcome eel innate immunity relies on a virulence plasmid (pVvbt2) specific for biotype 2 (Bt2) strains. In the present study, we demonstrated that pVvbt2 encodes a host-specific iron acquisition system that depends on an outer membrane receptor for eel transferrin called Vep20. The inactivation of vep20 did not affect either bacterial growth in human plasma or virulence for mice, while bacterial growth in eel blood/plasma was abolished and virulence for eels was significantly impaired. Furthermore, vep20 is an iron-regulated ge…

Molecular response to TBT stress in marine sponge Suberites domuncula: proteolytical cleavage and phosphorylation of KRS_SD protein kinase

2003

Abstract Marine sponges as sessile filter feeders are inevitably under a constant influence of changes in their environment. Mediation of extracellular signals and regulation of cellular response to environmental stress is a key function of cellular protein kinases. Expression, proteolytical cleavage and phosphorylation of stress-responsive KRS_SD protein kinase, in control and tributyl-tin (TBT) treated sponges were investigated. In control sponge, two KRS_SD proteins were expressed: KRS_SD1 (54 kDa) corresponding to KRS_SD calculated molecular weight, and KRS_SD2 (50 kDa). Exposure of sponges to TBT resulted in alteration of KRS_SD1 and KRS_SD2 expression levels and their phosphorylation …

Bleaching of color of kraft pulp mill effluents and natural organic matter in lakes

2002

In situ changes in the color of lake water and biologically treated kraft pulp mill effluents mixed in lake water were examined in three lakes. In 1.7 m3 enclosures, the color (400–700 g Pt·m–3) of the mixture of pulp mill effluent and lake water remained similar for 4 months in darkness, whereas exposure to solar radiation resulted in 17–42% bleaching of color. During the summer stratification of a humic lake, the color (160 g Pt·m–3) of hypolimnetic water remained similar to that found during spring turnover, but the color of epilimnion decreased 13%. The measured rates of photochemical bleaching of color by solar radiation could explain the decrease of epilimnetic color. Attenuation of …

Steroidal saponins and flavan-3-ol glycosides from Dioscorea villosa

2006

Triterpene saponins from Schefflera abyssinica

2006

Solid State NMR Structure Analysis of the Antimicrobial Peptide Gramicidin S in Lipid Membranes: Concentration-Dependent Re-alignment and Self-Assemb…

2008

Antimicrobial peptides can kill bacteria by permeabilizing their cell membrane, as these amphiphilicmolecules interact favourably with lipid bilayers. This mechanism of action is attributed eitherto the formation of a peptide “carpet” on the membrane surface, or to a transmembranepore. However, the structure of such a pore has not yet been resolved under relevant conditions.Gramicidin S is a symmetrical cyclic β-sheet decapeptide, which has been previouslyshown by solid state NMR to lie flat on the membrane surface at low peptide:lipid ratios (≤ 1:80).Using highly sensitive 19F-NMR, supported by 15N-labelling,we found that gramicidin S can flip into an upright transmembrane alignment at hig…

Glycoside derivatives of scopoletin and β-sitosterol from Hymenodictyon floribundum

2003

Fatty acid composition of the seed lipids ofChamaerops humilisL. natural populations and its relation with the environment

2014

Seed lipids composition is a tool to discriminate among plant taxa and is related to phylogeny and biogeographic distribution. Aim of the present study was to evaluate the fatty acid (FA) composition of the seed lipids from nine natural Chamaerops humilis L. population and its relation with the climatic traits of the collection sites. The average seed lipids content was 54.8 g kg21 and the most represented FAs were oleic (478 g kg21 oil) and linoleic (230 g kg21 oil), with significant differences among the accessions. Most of the lipid traits significantly correlated with climatic traits. In particular, oleic acid negatively correlated with year potential evapotranspiration. These relations…

Peat humic acid properties and factors influencing their variability in a temperate bog ecosystem

2013

Studies of the properties of soil organic matter are essential for understanding the humification reactions and soil diagenesis processes. The aim of this study is to analyse properties of peat and peat humic acids as well as factors influencing their variability. Humic acids isolated from an ombrotrophic bog peat profile were used as study objects. Relations among peat age, decomposition and humification degree, botanical composition, and properties of peat humic acids (elemental, functional composition, spectral characteristics) were studied. The variability of peat properties was found to be less significant than the differences in the properties of peat-forming living matter, which indi…