Nuclear structures: Twinning and modulation in crystals

Crystal structure analysis is a standard technique routinely applied to single crystals as well as powders. However the process is not so straightforward if the crystal sample is affected by twinning or if the structure is modulated. In such cases the standard procedures are not directly applicable. The main purpose of this contribution is to show how to solve and refine such difficult structures. While for twinned structures the basic property of crystal – translation symmetry in three dimensional space–remains valid, for modulated crystals a special superspace theory must be exploited in order to describe the atomic structure with crystallographic methods generalized for superspace

Crystallographic textures

In material science, crystallographic texture is an important microstructural parameter which directly determines the anisotropy degree of most physical properties of a polycrystalline material at the macro scale. Its characterization is thus of fundamental and applied importance, and should ideally be performed prior to any physical property measurement or modeling. Neutron diffraction is a tool of choice for characterizing crystallographic textures: its main advantages over other existing techniques, and especially over the X-ray diffraction techniques, are due to the low neutron absorption by most elements. The obtained information is representative of a large number of grains, leading to a better accuracy of the statistical description of texture

Diffuse scattering

Diffuse neutron scattering covers a wide range of phenomena related to short range nuclear and magnetic orderings. Although it is “a priori” simple to measure, the underlying physics is often quite complex. Extracting useful and reliable information requires careful corrections and calibrations, and appropriate models of analysis, specifics for each physical case. This paper yields a partial and subjective glance on this specific subject, showing studies about chemical orderings in binary alloys and magnetic correlations in frustrated “spin ices” as examples

Purification de la vitellogénine d'une espèce de salmonidé (Oncorhynchus mykiss) et de deux espèces de cyprinidés (Gobio gobio et Leuciscus cephalus)

A two step purification protocol was developed to purify rainbow trout (Oncorhynchus mykiss) Vitellogenin (Vtg) and was successfully applied to Vtg of chub (Leuciscus cephalus) and gudgeon (Gobio gobio). Capture and intermediate purification were performed by anion exchange chromatography on a Resource Q column and a polishing step was performed by gel permeation chromatography on Superdex 200 column. This method is a rapid two step purification procedure that gave a pure solution of Vtg as assessed by silver staining electrophoresis and immunochemical characterisation.L'induction et la purification de la vitellogénine chez la truite, le chevaine et le goujon a été réalisée. Le but de ces expériences est de disposer de la protéine purifiée utilisable dans la méthode ELISA pour quantifier la vitellogénine présente dans les échantillons à partir d'une calibration spécifique pour chaque espèce. Le travail réalisé a permis la mise au point d'une méthode de purification à deux étapes chromatographiques

Evaluation des risques associés aux perturbateurs endocriniens.

International audienc

Development and validation of an enzyme-linked immunosorbent assay to measure vitellogenin in the zebrafish (Danio rerio)

International audienceIn this study, an enzyme-linked immunosorbent assay (ELISA) was developed to quantify vitellogenin (Vtg) in zebrafish (Danio rerio). Zebrafish Vtg (zf-Vtg) was purified from whole-body homogenates of estradiol-ex posed zebrafish, and polyclonal antibodies against zf-Vtg were raised. Using purified zf-Vtg as a standard and anti-zf-Vtg antibodies (DR-264), a competitive ELISA method was set up and validated, The working range of the assay is from 1 to 30 ng/ml (20-80% binding), and the detection limit is 0.4 ng/ml for purified zf-Vtg. In whole-body homogenates samples, the practical detection limit is higher than that for purified Vtg (40 ng/ml) due to matrix effect. The intra- and interassay variations were 4.7% and 14%, respectively, at 50% binding (n = 36). Its usefulness to detect changes in Vtg concentration in other cyprinid fish was also tested. In addition, the assay was used to assess Vtg induction in male zebrafish exposed to 17beta-estradiol (E-2). Exposure of male zebrafish to 0.1, 1, 10, and 100 mug/L of E-2 for 7 d led to a Vtg induction from the lowest concentration. The results show the suitability of the developed ELISA to quantify Vtg inductions in zebrafish, the cross-reactivity of DR264 antibodies with commonly used cyprinids, and the potential of zf-Vtg induction as a sensitive biochemical endpoint that could be used to detect estrogenic properties of chemical substances

Caractérisation histologique et anatomique de la gamétogenèse de Radix balthica (linnaeus, 1758) en comparaison avec Lymnaea stagnalis (linnaeus, 1758)

International audienceFreshwater gastropods are frequently used as model organisms to assess the effects of certain chemical substances. Among them Radix balthica and Lymnaea stagnalis are commonly used in the laboratory, mesocosm and fields tests. In order to determine the effects of pollutants and more particularly endocrine disrupting substances on the reproduction of these organisms, histopathological analyses can be used. Because data are still scarce in the literature, knowledge development on anatomy of reproductive tissues and gametogenesis is a preliminary step before any studies on the impact of contaminants on the reproduction of these gastropods. The characterization of the anatomy and gametogenesis of Radix balthica and Lymnaea stagnalis was thus performed in this study. Important morphological differences exist between the two species. Despite this, the gonads of the two gastropods species have similar histological structure. In both species, spermatogonia are clustered; spermatozoids are anchored in the Sertoli cells and the male cells alternate with the female cells that rest on the epithelium of the hermaphroditic gland. This study is a prerequisite for any further histopathological studies on contaminated individuals

Foreword

The international thematic school on “Crystallography and Neutrons” was organized in order to celebrate the International Year of Crystallography in 2014, under the patronage of the “Société Française de la Neutronique” (SFN) with the support of the CNRS and the European neutron facilities network NMI3. The school took place in September 2014 in Oléron, France, as first part of the “22ème Journées de la Neutronique” (JDN22). The school gathered participants from European countries and therefore the lectures were given in English. It intended to promote cooperation and networking among users of large scale facilities with researchers involved in the field of Crystallography

Biochemical effects of nonyphenol polyethoxylate adjuvant and two adjuvant-herbicide mixtures on three-spined stickleback (gasterosteus aculeatus L.).

Biochemical effects of nonyphenol polyethoxylate adjuvant and two adjuvant-herbicide mixtures on three-spined stickleback (gasterosteus aculeatus L.).. 13. International Symposium Pollutant Responses in Marine Organism