Dynamic Analysis of Vascular Morphogenesis Using Transgenic Quail Embryos

Background: One of the least understood and most central questions confronting biologists is how initially simple clusters or sheet-like cell collectives can assemble into highly complex three-dimensional functional tissues and organs. Due to the limits of oxygen diffusion, blood vessels are an essential and ubiquitous presence in all amniote tissues and organs. Vasculogenesis, the de novo self-assembly of endothelial cell (EC) precursors into endothelial tubes, is the first step in blood vessel formation [1]. Static imaging and in vitro models are wholly inadequate to capture many aspects of vascular pattern formation in vivo, because vasculogenesis involves dynamic changes of the endothelial cells and of the forming blood vessels, in an embryo that is changing size and shape. Methodology/Principal Findings: We have generated Tie1 transgenic quail lines Tg(tie1:H2B-eYFP) that express H2B-eYFP in all of their endothelial cells which permit investigations into early embryonic vascular morphogenesis with unprecedented clarity and insight. By combining the power of molecular genetics with the elegance of dynamic imaging, we follow the precise patterning of endothelial cells in space and time. We show that during vasculogenesis within the vascular plexus, ECs move independently to form the rudiments of blood vessels, all while collectively moving with gastrulating tissues that flow toward the embryo midline. The aortae are a composite of somatic derived ECs forming its dorsal regions and the splanchnic derived ECs forming its ventral region. The ECs in the dorsal regions of the forming aortae exhibit variable mediolateral motions as they move rostrally; those in more ventral regions show significant lateral-to-medial movement as they course rostrally. Conclusions/Significance: The present results offer a powerful approach to the major challenge of studying the relative role(s) of the mechanical, molecular, and cellular mechanisms of vascular development. In past studies, the advantages of the molecular genetic tools available in mouse were counterbalanced by the limited experimental accessibility needed for imaging and perturbation studies. Avian embryos provide the needed accessibility, but few genetic resources. The creation of transgenic quail with labeled endothelia builds upon the important roles that avian embryos have played in previous studies of vascular development

High temperature antimony ion implantation in strained silicon-on-insulator

We present experimental results on shallow junction formation in strained silicon-on-insulator by antimony ion implantation and standard rapid thermal processing. An attempt is made to obtain Sb activation without layer amorphization by implanting Sb at elevated temperature. The focus is on studying the Sb activation during implantation at high temperature. Rutherford backscattering spectrometry and secondary ion mass spectroscopy are employed for characterization of Sb diffusion in amorphous and crystalline Si. The results are discussed in terms of the defect reaction kinetics involved. (C) 2009 Elsevier Ltd. All rights reserved

Evidence for ion beam induced attenuations of the static hyperfine field at recoil implanted 56^{56}Fe ions in Fe host

It is now considered that the information available in bibliographical databases is dated, validated through a long process which does not make it very innovative. Furthermore, database processing is normally performed using boolean operators : the results obtained from a query provides a sum of expected information which, in itself, does not deliver any novelty. Don Swanson's work demonstrates the unsuspected potential of bibliographical databases in revealing and discovering knowledge.The interest of his approach lies less on the available information itself than on the methodology used to disclose new knowledge. This general methodology fits perfectly well within an environment of validated and structured information, as is the case for bibliographical data. The expression Knowledge Discovery in Databases (KDD) indicates a methodology which creates new knowledge based upon bibliographical data. In this article, we will cover the principals of KDD based on Don Swanson's work as well as the method used to disclose knowledge within biomedical bibliographical databases

Boron activation and diffusion in silicon and strained silicon-on-insulator by rapid thermal and flash lamp annealings

We present experimental results on the activation and diffusion behaviors of boron in silicon-on-insulator and strained silicon-on-insulator using standard rapid thermal processing treatments as well as flash lamp annealing. After boron implantation at different doses and at a low energy of 1 keV, samples were annealed to activate the dopants, and secondary ion mass spectrometry and Hall measurements were carried out to determine boron diffusion and the amount of activated dopants, respectively. In contrast to rapid thermal annealing, flash lamp annealing enables the activation without significant diffusion of dopants. In addition, we investigated the effect of coating the samples with antireflection layers to increase the absorbed energy during flash annealing. As a result, the activation was increased significantly to values comparable with the activation obtained with standard annealing. Furthermore, the relation between the observed boron diffusion and activation as a function of the implantation and annealing parameters is discussed in terms of the kinetics of the defects involved in these processes. (C) 2008 American Institute Of Physics

Oekotoxikologie von Agrochemikalien. Biologische Risikoabschaetzung mit Hilfe terrestrischer Multi-Spezies-Testsysteme (Mesocosmen)

Available from TIB Hannover: F00B532+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Oekotoxikologie von Agrochemikalien. Biologische Risikoabschaetzung mit Hilfe terrestrischer Multi-Spezies-Testsysteme (Mesocosmen)

Available from TIB Hannover: F00B532+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman