Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

The Function of TIF2/GRIP1 in Mouse Reproduction Is Distinct from Those of SRC-1 and p/CIP

Abstract: Human TIF2 (hTIF2) is a member of the p160 family of nuclear receptor coactivators, which includes SRC-1 and p/CIP. Although the functions of hTIF2 and of its mouse homolog (GRIP1 or mTIF2) have been clearly established in vitro, their physiological role remains elusive. Here, we have generated mice lacking mTIF2/GRIP1 and examined their phenotype with a particular emphasis on reproductive functions. TIF2−/− mice are viable, but the fertility of both sexes is impaired. Male hypofertility is due to defects in both spermiogenesis (teratozoospermia) and age-dependent testicular degeneration, and TIF2 expression appears to be essential for adhesion of Sertoli cells to germ cells. Female hypofertility is due to a placental hypoplasia that most probably reflects a requirement for maternal TIF2 in decidua stromal cells that face the developing placenta. We conclude that TIF2 plays a critical role in mouse reproductive functions, whereas previous reports have not revealed serious fertility impairment in SRC-1−/− or p/CIP−/− mutants. Thus, even though the three p160 coactivators exhibit strong sequence homology and similar activity in assays in vitro, they play distinct physiological roles in vivo, as their genetic eliminations result in distinct pathologies.

Generating entangled microwave radiation over two transmission lines.

Abstract: Using a superconducting circuit, the Josephson mixer, we demonstrate the first experimental realization of spatially separated two-mode squeezed states of microwave light. Driven by a pump tone, a first Josephson mixer generates, out of quantum vacuum, a pair of entangled fields at different frequencies on separate transmission lines. A second mixer, driven by a π-phase shifted copy of the first pump tone, recombines and disentangles the two fields. The resulting output noise level is measured to be lower than for the vacuum state at the input of the second mixer, an unambiguous proof of entanglement. Moreover, the output noise level provides a direct, quantitative measure of entanglement, leading here to the demonstration of 6 Mebit · s(-1) (mega entangled bits per second) generated by the first mixer.

Molecular and Clinical Correlations in Spinocerebellar Ataxia 2: A Study of 32 Families

Abstract: Spinocerebellar ataxia 2 (SCA2) is caused by the ex-pansion of an unstable CAG repeat encoding a poly-glutamine tract. One hundred and eighty four indexpatients with autosomal dominant cerebellar ataxiatype I were screened for this mutation. We found ex-pansion in 109 patients from 30 families of differentgeographical origins (15%) and in two isolated caseswith no known family histories (2%). The SCA2chromosomes contained from 34 to 57 repeats andconsisted of a pure stretch of CAG, whereas all testednormal chromosomes (14–31 repeats), except one with14 repeats, were interrupted by 1–3 repeats of CAA. Asin other diseases caused by unstable mutations, astrong negative correlation was observed between theage at onset and the size of the CAG repeat ( r = –0.81).The frequency of several clinical signs such as myo-clonus, dystonia and myokymia increased with thenumber of CAG repeats whereas the frequency ofothers was related to disease duration. The CAG repeatwas highly unstable during transmission with vari-ations ranging from –8 to +12, and a mean increase of+2.2, but there was no significant difference accordingto the parental sex. This instability was confirmed bythe high degree of gonadal mosaicism observed insperm DNA of one patient.INTRODUCTIONAutosomal dominant cerebellar ataxias (ADCAs) are a clinicallyheterogeneous group of neurodegenerative disorders. Type IADCA, characterized by the variable association of cerebellarataxia with supranuclear ophthalmoplegia, optic atrophy, extra-pyramidal signs, dementia and amyotrophy (1,2), is geneticallyheterogeneous. Five different loci have been mapped: SCA1 on6p ( 3), SCA2 on 12q ( 4), SCA3/MJD (Machado–Joseph disease)on 14q ( 5,6), SCA4 on 16q ( 7) and SCA5 on 11cen ( 8). SCA1 ( 9)and SCA3/MJD ( 10) were the first to be identified. The mutationis the expansion of an unstable CAG repeat encoding apolyglutamine tract. Recently, Trottier et al. (11), using amonoclonal antibody which specifically recognizes proteins withpolyglutamine expansions, detected an abnormal 150 kDa proteinin SCA2 patients, suggesting that this disorder was caused bytranslated CAG expansions. Very recently, three independentgroups (12–14) identified the SCA2 gene which carries anexpanded CAG repeat in its coding sequence in patients,confirming this hypothesis. The gene encodes a 1312 amino acidprotein of unknown function (12,14).

Water-mediated structuring of bone apatite

Abstract: It is well known that organic molecules from the vertebrate extracellular matrix of calcifying tissues are essential in structuring the apatite mineral. Here, we show that water also plays a structuring role. By using solid-state nuclear magnetic resonance, wide-angle X-ray scattering and cryogenic transmission electron microscopy to characterize the structure and organization of crystalline and biomimetic apatite nanoparticles as well as intact bone samples, we demonstrate that water orients apatite crystals through an amorphous calcium phosphate-like layer that coats the crystalline core of bone apatite. This disordered layer is reminiscent of those found around the crystalline core of calcified biominerals in various natural composite materials in vivo. This work provides an extended local model of bone biomineralization.

Towards systems materials engineering.

Abstract: System-level planning of theoretical and experimental efforts is increasingly important for the development of modern materials science.