Molecular Characterization of the Gastrula in the Turtle Emys orbicularis: An Evolutionary Perspective on Gastrulation

Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Anticoagulation régionale au citrate pour l’épuration extrarénale continue [Regional citrate anticoagulation for continuous renal replacement therapy]

Regional citrate anticoagulation (RCA) is currently the recommended anticoagulation modality for continuous renal replacement therapy. Indeed, compared with systemic heparinization, RCA is associated with a lower risk of bleeding, a longer circuit lifespan and a decrease nursing workload. However, RCA requires a strict protocol to be followed, as it might be associated with potentially severe complications, such as citrate accumulation. Citrate accumulation is rare and usually associated with specific situations : severe circulatory shock, liver failure and mitochondrial dysfunction. According to centers' expertise, these situations might represent contra-indications to RCA. This review presents RCA, its mode of action, associated risks and proposes an algorithm for patients' selection

A First Evaluation of OMNI®, A New Device for Continuous Renal Replacement Therapy.

Omni® (B. Braun, Germany) is a new-generation, continuous renal replacement therapy (CRRT) machine designed to improve user interface, minimize downtime and optimize renal dose delivery. It was never tested in humans. We used Omni® to provide CRRT in 10 critically ill patients. We collected therapy data, metabolic parameters and evaluated user's satisfaction with a survey. CRRT was delivered using Omni® in CVVH-heparin (6 patients) and CVVHD-citrate (4 patients) modes for a total duration of 617.7 h. No adverse event was observed. The mean filter life was 22.8 (CVVH-heparin) and 33.5 (CVVHD-citrate) h. Alarms-related downtime corresponded to 5.9% of total therapy time. Delivered renal dose was 96.6% of prescribed. Satisfactory metabolic control and fluid removal were achieved. Overall, users evaluated interface, design and usability as excellent. CRRT in CVVH-heparin and CVVHD-citrate modes was provided using Omni® in a safe and efficient way for 10 critically ill patients. Video Journal Club 'Cappuccino with Claudio Ronco' at http://www.karger.com/?doi=451053

A gradient of Bmp7 specifies the tonotopic axis in the developing inner ear

The auditory systems of animals that perceive sounds in air are organized to separate sound stimuli into their component frequencies. Individual tones then stimulate mechanosensory hair cells located at different positions on an elongated frequency (tonotopic) axis. During development, immature hair cells located along the axis must determine their tonotopic position in order to generate frequency-specific characteristics. Expression profiling along the developing tonotopic axis of the chick basilar papilla (BP) identified a gradient of Bmp7. Disruption of that gradient in vitro or in ovo induces changes in hair cell morphologies consistent with a loss of tonotopic organization and the formation of an organ with uniform frequency characteristics. Further, the effects of Bmp7 in determination of positional identity are shown to be mediated through activation of the Mapk, Tak1. These results indicate that graded, Bmp7-dependent, activation of Tak1 signaling controls the determination of frequency-specific hair cell characteristics along the tonotopic axis

MicroRNA-214 controls skin and hair follicle development by modulating the activity of the Wnt pathway

YesSkin development is governed by complex programs of gene activation and silencing, including microRNA-dependent modulation of gene expression. Here, we show that miR-214 regulates skin morphogenesis and hair follicle (HF) cycling by targeting β-catenin, a key component of the Wnt signaling pathway. miR-214 exhibits differential expression patterns in the skin epithelium, and its inducible overexpression in keratinocytes inhibited proliferation, which resulted in formation of fewer HFs with decreased hair bulb size and thinner hair production. The inhibitory effects of miR-214 on HF development and cycling were associated with altered activities of multiple signaling pathways, including decreased expression of key Wnt signaling mediators β-catenin and Lef-1, and were rescued by treatment with pharmacological Wnt activators. Finally, we identify β-catenin as one of the conserved miR-214 targets in keratinocytes. These data provide an important foundation for further analyses of miR-214 as a key regulator of Wnt pathway activity and stem cell functions during normal tissue homeostasis, regeneration, and aging

Evolutionary origin and functional divergence of totipotent cell homeobox genes in eutherian mammals

BACKGROUND: A central goal of evolutionary biology is to link genomic change to phenotypic evolution. The origin of new transcription factors is a special case of genomic evolution since it brings opportunities for novel regulatory interactions and potentially the emergence of new biological properties. RESULTS: We demonstrate that a group of four homeobox gene families (Argfx, Leutx, Dprx, Tprx), plus a gene newly described here (Pargfx), arose by tandem gene duplication from the retinal-expressed Crx gene, followed by asymmetric sequence evolution. We show these genes arose as part of repeated gene gain and loss events on a dynamic chromosomal region in the stem lineage of placental mammals, on the forerunner of human chromosome 19. The human orthologues of these genes are expressed specifically in early embryo totipotent cells, peaking from 8-cell to morula, prior to cell fate restrictions; cow orthologues have similar expression. To examine biological roles, we used ectopic gene expression in cultured human cells followed by high-throughput RNA-seq and uncovered extensive transcriptional remodelling driven by three of the genes. Comparison to transcriptional profiles of early human embryos suggest roles in activating and repressing a set of developmentally-important genes that spike at 8-cell to morula, rather than a general role in genome activation. CONCLUSIONS: We conclude that a dynamic chromosome region spawned a set of evolutionarily new homeobox genes, the ETCHbox genes, specifically in eutherian mammals. After these genes diverged from the parental Crx gene, we argue they were recruited for roles in the preimplantation embryo including activation of genes at the 8-cell stage and repression after morula. We propose these new homeobox gene roles permitted fine-tuning of cell fate decisions necessary for specification and function of embryonic and extra-embryonic tissues utilised in mammalian development and pregnancy.This work was supported primarily by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013 ERC grant 268513) to PWHH. In addition, support was provided by the Spanish Ministry of Economy and Competitiveness (BFU2014-55076-P) to MI and a fellowship from ‘la Caixa’-Severo Ochoa to CDR