Listening to music reduces eye movements

Listening to music can change the way that people visually experience the environment, probably as a result of an inwardly directed shift of attention. We investigated whether this attentional shift can be demonstrated by reduced eye movement activity, and if so, whether that reduction depends on absorption. Participants listened to their preferred music, to unknown neutral music, or to no music while viewing a visual stimulus (a picture or a film clip). Preference and absorption were significantly higher for the preferred music than for the unknown music. Participants exhibited longer fixations, fewer saccades, and more blinks when they listened to music than when they sat in silence. However, no differences emerged between the preferred music condition and the neutral music condition. Thus, music significantly reduces eye movement activity, but an attentional shift from the outer to the inner world (i.e., to the emotions and memories evoked by the music) emerged as only one potential explanation. Other explanations, such as a shift of attention from visual to auditory input, are discussed

Concomitant effects of light and temperature diel variations on the growth rate and lipid production of Dunaliella salina

International audienceThe microalgae Dunaliella salina has the capacity to grow in salterns at high salinity. In this particular shallow environment, D. salina is exposed to strong light and temperature variations and has developed various strategies such as cell cycle adaptation and storage of dedicated metabolites. The effects of light/dark cycles have already been studied, but few works focused on the concomitant effects of light and temperature variations characterizing salterns and outdoor conditions. In this study, growth, carbon and nitrogen storage, pigments and lipid production of D. Salina were measured in laboratory conditions mimicking the outdoor light and temperature conditions. A control experiment with constant temperature was carried out with light variations only. During the night, cell respiration was correlated with temperature, following an Arrhenius law. Many differences with the control at constant temperature confirmed that temperature variations are a crucial parameter in outdoor conditions and should be taken into account to predict growth. Triglyceride and pigment production was tightly linked to the light dark cycle

Polyoxometalates as a Novel Class of Artificial Proteases: Selective Hydrolysis of Lysozyme under Physiological pH and Temperature Promoted by a Cerium(IV) Keggin-Type Polyoxometalate

Hen-egg-white lysozyme (HEWL) is specifically cleaved at the Trp28-Val29 and Asn44-Arg45 peptide bonds in the presence of a Keggin-type [Ce(α-PW11O39)2]10- polyoxometalate (POM; 1) at pH 7.4 and 37 °C. The reactivity of 1 towards a range of dipeptides was also examined and the calculated reaction rates were comparable to those observed for the hydrolysis of HEWL. Experiments with α-lactalbumin (α-LA), a protein that is structurally highly homologous to HEWL but has a different surface potential, showed no evidence of hydrolysis, which indicates the importance of electrostatic interactions between 1 and the protein surface for the hydrolytic reaction to occur. A combination of spectroscopic techniques was used to reveal the molecular interactions between HEWL and 1 that lead to hydrolysis. NMR spectroscopy titration experiments showed that on protein addition the intensity of the 31P NMR signal of 1 gradually decreased due to the formation of a large protein/polyoxometalate complex and completely disappeared when the HEWL/1 ratio reached 1:2. Circular dichroism (CD) measurements of HEWL indicate that addition of 1 results in a clear decrease in the signal at λ=208 nm, which is attributed to changes in the α-helical content of the protein. 15N-1H heteronuclear single quantum coherence (HSQC) NMR measurements of HEWL in the presence of 1 reveal that the interaction is mainly observed for residues that are located in close proximity to the first site in the α-helical part of the structure (Trp28-Val29). The less pronounced NMR spectroscopic shifts around the second cleavage site (Asn44-Arg45), which is found in the β-strand region of the protein, might be caused by weaker metal-directed binding, compared with strong POM-directed binding at the first site. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

Molecular origin of the hydrolytic activity and fixed regioselectivity of a Zr(IV)-substituted polyoxotungstate as artificial protease

A multitechnique approach has been applied in order to identify the thermodynamic and kinetic parameters related to the regioselective hydrolysis of human serum albumin (HSA) promoted by the Wells-Dawson polyoxometalate (POM), K15H[Zr(α2-P2W17O 61)2]. Isothermal titration calorimetry (ITC) studies indicate that up to four POM molecules interact with HSA. While the first interaction site is characterized by a 1:1 binding and an affinity constant of 2×108M-1, the three remaining sites are characterized by a lower global affinity constant of 7×10 5M-1. The higher affinity constant at the first site is in accordance with a high quenching constant of 2.2×108M -1 obtained for fluorescence quenching of the Trp214 residue located in the only positively charged cleft of HSA, in the presence of K 15H[Zr(α2-P2W17O 61)2]. In addition, EuIII luminescence experiments with an EuIII-substituted POM analogue have shown the replacement of water molecules in the first coordination sphere of Eu III due to binding of the metal ion to amino acid side chain residues of HSA. All three interaction studies are in accordance with a stronger POM dominated binding at the positive cleft on the one hand, and interaction mainly governed by metal anchoring at the three remaining positions, on the other hand. Hydrolysis experiments in the presence of K15H[Zr(α 2-P2W17O61)2] have demonstrated regioselective cleavage of HSA at the Arg114-Leu115, Ala257-Asp258, Lys313-Asp314 or Cys392-Glu393 peptide bonds. This is in agreement with the interaction studies as the Arg114-Leu115 peptide bond is located in the positive cleft of HSA and the three remaining peptide bonds are each located near an upstream acidic residue, which can be expected to coordinate to the metal ion. A detailed kinetic study has evidenced the formation of additional fragments upon prolonged reaction times. Edman degradation of the additional reaction products has shown that these fragments result from further hydrolysis at the initially observed cleavage positions, indicating a fixed selectivity for K 15H[Zr(α2-P2W17O 61)2]. Making the cut: A multitechnique approach has been applied to the identification of the thermodynamic and kinetic parameters related to the regioselective hydrolysis of human serum albumin promoted by the Wells-Dawson polyoxometalate (POM), K15H[Zr(α2- P2W17O61)2] (see figure). All interaction studies are in accordance with the observed hydrolysis fragments which are the result of combined POM-dominated binding and interactions governed by metal anchoring. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe