The embryonic node functions as an instructive stem cell niche

In warm-blooded vertebrate embryos (mammals and birds), the body forms from a growth zone at the tail end. Hensen’s node, a region which induces and patterns the neural axis is located within this growth zone. The node also contains the precursors of neural, mesodermal and endodermal structures along the midline and has been suggested to contain a small population of resident stem cells. However, it is unknown whether the rest of the node constitutes an instructive stem cell niche, specifying stem cell behaviour. Here we combine transplantation of a single cell in vivo with single-cell mRNA sequencing in the chick and show that when made to enter the node, non-node-progenitor cells become resident and gain stem cell behaviour. These cells preferentially express G2/M phase cell-cycle related genes and are concentrated in posterior sub-regions of the node. The posterior part of the node therefore behaves as an instructive stem cell niche. These results demonstrate a new function for the vertebrate node during development

Development of ultrasound detection in American shad (Alosa sapidissima)

It has recently been shown that a few fish species, including American shad (Alosa sapidissima; Clupeiformes), are able to detect sound up to 180 kHz, an ability not found in most other fishes. Initially, it was proposed that ultrasound detection in shad involves the auditory bullae, swim bladder extensions found in all members of the Clupeiformes. However, while all clupeiformes have bullae, not all can detect ultrasound. Thus, the bullae alone are not sufficient to explain ultrasound detection. In this study, we used a developmental approach to determine when ultrasound detection begins and how the ability to detect ultrasound changes with ontogeny in American shad. We then compared changes in auditory function with morphological development to identify structures that are potentially responsible for ultrasound detection. We found that the auditory bullae and all three auditory end organs are present well before fish show ultrasound detection behaviourally and we suggest that an additional specialization in the utricle (one of the auditory end organs) forms coincident with the onset of ultrasound detection. We further show that this utricular specialization is found in two clupeiform species that can detect ultrasound but not in two clupeiform species not capable of ultrasound detection. Thus, it appears that ultrasound-detecting clupeiformes have undergone structural modification of the utricle that allows detection of ultrasonic stimulation

From Citywide to Neighborhood-Based: Two Decades of Learning, Prioritization, and Strategic Action to Build the Skillman Foundation’s Youth-Development Systems

· This article explores the Skillman Foundation’s shift in its approach to fulfilling its mission to improve the lives of children and youth and to making grants – moving from a traditional grantmaker to a place-based investor and change-maker. · Three aspects of Skillman’s approach have directly shaped the evolution of its youth-development investments: recognizing Detroit’s economic, social, political, and environmental challenges; articulating overarching goals to provide direction and setting priorities for the scope and focus of its programmatic work; and using rapid learning to inform strategic decisions and social-innovation practices designed to tackle deeply entrenched problems. · This article reflects on the foundation’s evolution over two decades of learning, prioritization, and strategic action in its efforts to build and sustain outcome-focused youth-development systems

Föderalismuskommission II: Neue Schuldenregelung für Bund und Länder und Altschuldenhilfe - wie sollten die Finanzbeziehungen von Bund und Ländern neu geordnet werden?

Um die öffentliche Verschuldung in Deutschland tatsächlich zurückzuführen, ist eine grundsätzliche Neuordnung der Bund-Länder-Finanzbeziehungen nötig. Nach Meinung von Jörg-Uwe Hahn, FDP Hessen und Mitglied der Föderalismuskommission II, bedarf es, neben eines möglichst strikten Neuverschuldungsverbots, einer Stärkung der Finanzautonomie insbesondere der Bundesländer, aber auch von Bund und Gemeinden. Notwendig sei es, im Sinne einer echten Steuerautonomie den Ländern dort, wo ihnen der Steuerertrag zusteht, auch die Gesetzgebungskompetenz einzuräumen. Kai A. Konrad, Wissenschaftszentrum Berlin für Sozialforschung und Freie Universität Berlin, sieht weniger beim Bund, sondern vor allem bei den Ländern das zentrale Problem. Sie könnten in der extremen Haushaltsnotlage auf eine Rettung durch die Bund-Länder-Gemeinschaft hoffen. Die Reform werde anscheinend von vielen Akteuren "als willkommene Chance gesehen, damit Umverteilungsgewinne zu Lasten anderer Gebietskörperschaften zu erzielen". Eckhard Janeba, Universität Mannheim und Mitglied des wissenschaftlichen Beirats beim Bundesministerium für Wirtschaft und Technologie, unterstreicht, dass konstitutionelle Regeln zur Begrenzung von Verschuldung ein wichtiges Instrument seien, um eine langfristig solide Finanzpolitik zu erreichen, sieht aber darin die Gefahr, "dass die Entscheidung über den Haushalt und damit die Verschuldung zu einem Expertenproblem wird, von der die politische Öffentlichkeit abgekoppelt ist. Diesem sollte entgegengewirkt werden. Der Vorschlag des Wissenschaftlichen Beirats beim BMWI geht in die richtige Richtung, indem er auf eine Identifikation der Verschuldungsursachen verzichtet und durch eine qualifizierte Mehrheitsentscheidung den Haushaltsbeschluss in den politischen Mittelpunkt zurückführt." Max Groneck und Robert C. Plachta, Universität zu Köln, stellen ein Reformkonzept vor.Föderalismus, Reform, Öffentliche Schulden, Deutschland

Body Composition Characteristics of a Load-Capacity Model: Age-Dependent and Sex-Specific Percentiles in 5- To 17-Year-Old Children

Introduction: Body composition assessment is superior to the use of body mass index (BMI) to characterize the nutritional status in pediatric populations. For data interpretation, suitable reference data are needed; hence, we aimed to generate age-dependent and sex-specific body composition reference data in a larger population of children and adolescents in Germany. Methods: This is a cross-sectional study on a representative group of 15,392 5- to 17-year-old children and adolescents. Body composition was assessed by bioelectrical impedance analysis using a population-specific algorithm validated against air displacement plethysmography. Age- and sex-specific percentiles for BMI, fat mass index (FMI), fat-free mass index (FFMI), and a “load-capacity model” (characterized by the ratios of fat mass [FM]/ fatt-free mass [FFM] and FM/FFM2) were modeled using the LMS method. Results: BMI, FMI, FFMI, FM/FFM, and FM/FFM2 curves showed similar shapes between boys and girls with steady increases in BMI, FMI, and FFMI, while FM/FFM2-centiles decreased during early childhood and adolescence. Sex differences were observed in FMI and FM/FFM percentiles with increases in FMI up to age 9 years followed by a steady decrease in FM/FFM during and after puberty with a fast-growing FFMI up to age 17 in boys. The prevalence of low FFM relative to FM reached more than 60% in overweight children and adolescents. Conclusion: These pediatric body composition reference data enable physicians and public health scientists to monitor body composition during growth and development and to interpret individual data. The data point out to an early risk of sarcopenia in overweight children and adolescents

Large-Scale Demonstration of Liquid Hydrogen Storage with Zero Boiloff for In-Space Applications

Cryocooler and passive insulation technology advances have substantially improved prospects for zero-boiloff cryogenic storage. Therefore, a cooperative effort by NASA s Ames Research Center, Glenn Research Center, and Marshall Space Flight Center (MSFC) was implemented to develop zero-boiloff concepts for in-space cryogenic storage. Described herein is one program element - a large-scale, zero-boiloff demonstration using the MSFC multipurpose hydrogen test bed (MHTB). A commercial cryocooler was interfaced with an existing MHTB spray bar mixer and insulation system in a manner that enabled a balance between incoming and extracted thermal energy

Gastric Emphysema: An Etiologic Classification

I Gas within the wall of the stomach is a rare radiologic finding. The stomach has been the least often reported site of intramural gas in the hollow viscera. Based on etiology, gas in the wall of the stomach can be classified as either gastric emphysema or emphysematous gastritis. Gastric emphysema may be classified into traumatic, pulmonary or obstructive types depending upon the mechanism and pathogenesis. Three cases of gastric emphysema, each of different etiology, are presented to emphasize the subclassification of gastric emphysema. The clinical and prognostic significance of this classification is emphasized.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72543/1/j.1440-1673.1984.tb02363.x.pd

The nuclear lamina couples mechanical forces to cell fate in the preimplantation embryo via actin organization

During preimplantation development, contractile forces generated at the apical cortex segregate cells into inner and outer positions of the embryo, establishing the inner cell mass (ICM) and trophectoderm. To which extent these forces influence ICM-trophectoderm fate remains unresolved. Here, we found that the nuclear lamina is coupled to the cortex via an F-actin meshwork in mouse and human embryos. Actomyosin contractility increases during development, upregulating Lamin-A levels, but upon internalization cells lose their apical cortex and downregulate Lamin-A. Low Lamin-A shifts the localization of actin nucleators from nucleus to cytoplasm increasing cytoplasmic F-actin abundance. This results in stabilization of Amot, Yap phosphorylation and acquisition of ICM over trophectoderm fate. By contrast, in outer cells, Lamin-A levels increase with contractility. This prevents Yap phosphorylation enabling Cdx2 to specify the trophectoderm. Thus, forces transmitted to the nuclear lamina control actin organization to differentially regulate the factors specifying lineage identity