During gastrulation, a cascade of inductive tissue interactions converts pre-existing polarity in the mammalian embryo into antero-posterior pattern. This process is triggered by Nodal, a protein related to transforming growth factor-beta (TFG-beta) that is expressed in the epiblast and visceral endoderm, and its co-receptor Cripto, which is induced downstream of Nodal. Here we show that the proprotein convertases Spc1 and Spc4 (also known as Furin and Pace4, respectively) are expressed in adjacent extraembryonic ectoderm. They stimulate Nodal maturation after its secretion and are required in vivo for Nodal signalling. Embryo explants deprived of extraembryonic ectoderm phenocopy Spc1(-/-); Spc4(-/-) double mutants in that endogenous Nodal fails to induce Cripto. But recombinant mature Nodal, unlike uncleaved precursor, can efficiently rescue Cripto expression. Cripto is also expressed in explants treated with bone morphogenetic protein 4 (BMP4). This indicates that Nodal may induce Cripto through both a signalling pathway in the embryo and induction of Bmp4 in the extraembryonic ectoderm. A lack of Spc1 and Spc4 affects both pathways because these proteases also stimulate induction of Bmp4.

Cold seep ecosystems occur on active and passive continental margins. Chemosynthesisbased communities depend on autochtonous and local chemical energy and produce organic carbon in large quantities through microbial chemosynthesis. The high organic carbon production leads to the large size of the fauna and the high biomass of the communities. The remarkable abundance of giant tubeworms (vestimentiferans) and large bivalves (i.e. Vesicomyidae, Myt ilidae and others) is one of the most striking features of such communities and one of the best indicators or tracers of fluid emissions at the seafloor. Cold seep communities are known since about 15 years and have shown that the chemoautotrophy and many symbiont containing organisms are not unique to hydrothermal vents . Ecosystem characteristics and functioning in continental margin habitats are incompletely understood and we do not know how detritus and chemosynthesis-based ecosystems interact. There is a clear need of more field investigations. But with progress in deep-sea submersible technology, our understanding continues to grow. Following a recent review that focused on biogeographical trends and comparisons with hydrothermal vent communities (Sibuet and Olu 1998), we review here the ecology of chemosynthesis-based communities from several cold seep areas. Our synthesis addresses biodiversity and abundance fluctuations and distribution patterns linked to geological and fluid venting features. The diversity of the "symbiotic" fauna expressed as species richness decreases with ocean depth. Species composition is an indicator of the biotope variability. The spatial extension of active seep areas is highly variable from hundreds of square meters to several hectares. Three distinct categories of cold seep sites are recognised. The shape, density and biomass of aggregations reflect the intensity of fluid flow, and characterise fluid circulation and different expulsion pathways through geological structures.

The novel automatic mapping system was rapid, safe, and efficacious in mapping a variety of cardiac arrhythmias in humans. Further clinical research is needed to optimize its use in the ablation of complex arrhythmias.

Diagnosis of arrhythmic disorders is challenging because of their short-lasting, intermittent character. Conventional technologies of noninvasive ambulatory rhythm monitoring are limited by modest sensitivity. We present a novel form of wearable electrocardiogram (ECG) sensors providing an alternative tool for long-term rhythm monitoring with the potential of increased sensitivity to detect intermittent or subclinical arrhythmia. The objective was to assess the signal quality and R-R coverage of a wearable ECG sensor system compared to a standard 3-lead Holter. In this phase-1 trial, healthy individuals underwent 24-h simultaneous rhythm monitoring using the OMsignal system together with a 3-lead Holter recording. The OMsignal system consists of a garment (bra or shirt) with integrated sensors recording a single-lead ECG and an acquisition module for data storage and processing. Head-to-head signal quality was assessed regarding adequate P-QRS-T distinction and was performed by three electrophysiologists blinded to the recording technology. The accuracy of signal coverage was assessed using Bland-Altman analysis. Fifteen individuals underwent simultaneous 24-h recording. Signal quality and accuracy of the OMgaments was equivalent to Holter-monitoring (84% vs 93% electrophysiologists rating, p = 0.06). Signal coverage of R-R intervals showed a very close overlay between the OMsignal system and Holter signals, mean difference in heart rate of 2 5 bpm. The noise level of OMgarments was comparable to Holter recording. OMgarments provide high signal quality for adequate rhythm analysis, representing a promising novel technology for long-term non-invasive ECG monitoring.