7 research outputs found
Tbx6 Regulates Left/Right Patterning in Mouse Embryos through Effects on Nodal Cilia and Perinodal Signaling
Background: The determination of left/right body axis during early embryogenesis sets up a developmental cascade that coordinates the development of the viscera and is essential to the correct placement and alignment of organ systems and vasculature. Defective left-right patterning can lead to congenital cardiac malformations, vascular anomalies and other serious health problems. Here we describe a novel role for the T-box transcription factor gene Tbx6 in left/right body axis determination in the mouse. Results: Embryos lacking Tbx6 show randomized embryo turning and heart looping. Our results point to multiple mechanisms for this effect. First, Dll1, a direct target of Tbx6, is down regulated around the node in Tbx6 mutants and there is a subsequent decrease in nodal signaling, which is required for laterality determination. Secondly, in spite of a lack of expression of Tbx6 in the node, we document a profound effect of the Tbx6 mutation on the morphology and motility of nodal cilia. This results in the loss of asymmetric calcium signaling at the periphery of the node, suggesting that unidirectional nodal flow is disrupted. To carry out these studies, we devised a novel method for direct labeling and live imaging cilia in vivo using a genetically-encoded fluorescent protein fusion that labels tubulin, combined with laser point scanning confocal microscopy for direct visualization of cilia movement. Conclusions: We conclude that the transcription factor gene Tbx6 is essential for correct left/right axis determination in th
Measurement of ZZ production in leptonic final states at {\surd}s of 1.96 TeV at CDF
In this paper we present a precise measurement of the total ZZ production
cross section in pp collisions at {\surd}s= 1.96 TeV, using data collected with
the CDF II detector corresponding to an integrated luminosity of approximately
6 fb-1. The result is obtained by combining separate measurements in the
four-charged (lll'l'), and two-charged-lepton and two-neutral-lepton (llvv)
decay modes of the Z. The combined measured cross section for pp {\to} ZZ is
1.64^(+0.44)_(-0.38) pb. This is the most precise measurement of the ZZ
production cross section in 1.96 TeV pp collisions to date.Comment: submitted to Phys. Rev. Let
All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run
We present results from a search for gravitational-wave bursts in the data
collected by the LIGO and Virgo detectors between July 7, 2009 and October 20,
2010: data are analyzed when at least two of the three LIGO-Virgo detectors are
in coincident operation, with a total observation time of 207 days. The
analysis searches for transients of duration < 1 s over the frequency band
64-5000 Hz, without other assumptions on the signal waveform, polarization,
direction or occurrence time. All identified events are consistent with the
expected accidental background. We set frequentist upper limits on the rate of
gravitational-wave bursts by combining this search with the previous LIGO-Virgo
search on the data collected between November 2005 and October 2007. The upper
limit on the rate of strong gravitational-wave bursts at the Earth is 1.3
events per year at 90% confidence. We also present upper limits on source rate
density per year and Mpc^3 for sample populations of standard-candle sources.
As in the previous joint run, typical sensitivities of the search in terms of
the root-sum-squared strain amplitude for these waveforms lie in the range 5
10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs
entails the most sensitive all-sky search for generic gravitational-wave bursts
and synthesizes the results achieved by the initial generation of
interferometric detectors.Comment: 15 pages, 7 figures: data for plots and archived public version at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=70814&version=19, see
also the public announcement at
http://www.ligo.org/science/Publication-S6BurstAllSky
Retinoic acid coordinates somitogenesis and leftâright patterning in vertebrate embryos
Cardiac Looping and the Left-Right Axis: Integrating Morphologic, Molecular, and Genetic Analyses of Vertebrate Left-Right Asymmetry
Left-right axis development: examples of similar and divergent strategies to generate asymmetric morphogenesis in chick and mouse embryos
Search for gravitational waves from binary black hole inspiral, merger, and ringdown
We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1â99Mâ and total masses of 25â100Mâ. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19Mââ€m1, m2â€28Mâ binary black-hole systems with negligible spin to be no more than 2.0ââMpcâ3âMyrâ1 at 90% confidence