Expression pattern of arenicins—the antimicrobial peptides of polychaete Arenicola marina

Immune responses of invertebrate animals are mediated through innate mechanisms, among which production of antimicrobial peptides play an important role. Although evolutionary Polychaetes represent an interesting group closely related to a putative common ancestor of other coelomates, their immune mechanisms still remain scarcely investigated. Previously our group has identified arenicins - new antimicrobial peptides of the lugworm Arenicola marina, since then these peptides were thoroughly characterized in terms of their structure and inhibitory potential. In the present study we addressed the question of the physiological functions of arenicins in the lugworm body. Using molecular and immunocytochemical methods we demonstrated that arencins are expressed in the wide range of the lugworm tissues - coelomocytes, body wall, extravasal tissue and the gut. The expression of arenicins is constitutive and does not depend on stimulation of various infectious stimuli. Most intensively arenicins are produced by mature coelomocytes where they function as killing agents inside the phagolysosome. In the gut and the body wall epithelia arenicins are released from producing cells via secretion as they are found both inside the epithelial cells and in the contents of the cuticle. Collectively our study showed that arenicins are found in different body compartments responsible for providing a first line of defence against infections, which implies their important role as key components of both epithelial and systemic branches of host defence

Light scattering spectra of supercooled molecular liquids

The light scattering spectra of molecular liquids are derived within a generalized hydrodynamics. The wave vector and scattering angle dependences are given in the most general case and the change of the spectral features from liquid to solidlike is discussed without phenomenological model assumptions for (general) dielectric systems without long-ranged order. Exact microscopic expressions are derived for the frequency-dependent transport kernels, generalized thermodynamic derivatives and the background spectra.Comment: 12 page

THERMAL AND STIMULATED MOLECULAR SCATTERING OF LIGHT IN LIQUIDS

On étudie la dépendance en fonction de la température du spectre de la lumière diffusée par les fluctuations d'anisotropie dans des liquides (salol et benzophénone). On observe deux branches pour l'écartement entre les composantes du doublet dû aux ondes transverses. Il y a branche à basse température, pour laquelle l'écartement entre composantes décroît quand la température croît, et il y a une branche à haute température, pour laquelle l'écartement décroît quand la température décroît. Dans les ailes de la raie Rayleigh des liquides que nous avons étudiés, on peut distinguer deux lorentziennes dont les largeurs diffèrent de deux ordres de grandeur. On définit deux temps de relaxation à partir de ces données. En se servant de ces mesures et des données de la dépendance en fonction de la température d'un autre paramètre, on montre que la théorie de Rytov avec deux temps de relaxation pour l'anisotropie décrit très bien la dépendance en fonction de la température de l'écartement entre les composantes de la structure fine des ailes de la raie Rayleigh. On a aussi mesuré le gain dû à la diffusion Rayleigh stimulée dépolarisée. On a observé le phénomène de la diffusion thermique stimulée due à l'effet électrocalorique dans les liquides qu'on a étudiés.The temperature dependence of the spectrum of the light scattered by anisotropy fluctuations is studied in liquids (salol and benzophenone). Two branches are observed in the temperature dependence of the splitting between the components of the doublet induced by shear waves. There is a low temperature branch, in which the splitting between the compoments decreases when temperature increases, and there is a high temperature branch, in which this splitting decreases when temperature decreases. In the Rayleigh line wing of the liquids that were studied one can distinguish two lorentzians the width of which differed by two orders. Two relaxation times and their temperature dependence are defined from these data. With the use of these measurements and data of the temperature dependence of an other parameter it is shown that Rytov's theory with two times of anisotropy relaxation describes very well the temperature behaviour of the splitting between components of Rayleigh wing fine structure. The gain of stimulated Rayleigh line wing light scattering is measured as well. The phenomenon of stimulated temperature light scattering due to an electrocalorical effect is observed in the liquids that were studied