Speed of reaction diffusion in embryogenesis

Reaction diffusion systems have been proposed as mechanisms for patterning during many stages of embryonic development. While much attention has been focused on the study of the steady state patterns formed and the robustness of pattern selection, much less is known about the time scales required for pattern formation. Studies of gradient formation by the diffusion of a single morphogen from a localized source have shown that patterning can occur on realistic time scales over distances of a millimeter or less. Reaction diffusion has the potential to give rise to patterns on a faster time scale, since all points in the domain can act as sources of morphogen. However, the speed at which patterning can occur has hitherto not been explored in depth. In this paper, we investigate this issue in specific reaction diffusion models and address the question of whether patterning via reaction diffusion is fast enough to be applicable to morphogenesis

Complex pattern formation in reaction diffusion systems with spatially-varying parameters

Spontaneous pattern formation in reaction–diffusion systems on a spatially homogeneous domain has been well studied. However, in embryonic development and elsewhere, pattern formation often takes place on a spatially heterogeneous background. We explore the effects of spatially varying parameters on pattern formation in one and two dimensions using the Gierer–Meinhardt reaction–diffusion model. We investigate the effect of the wavelength of a pre-pattern and demonstrate a novel form of moving pattern. We find that spatially heterogeneous parameters can both increase the range and complexity of possible patterns and enhance the robustness of pattern selection

Easy as 1,2,3: Create your own journal/ event pages with DigitalCommons@UNO

Creating a journal or event page with DigitalCommons is as easy as 1,2,3! Journal/ event pages on DigitalCommons@UNO possess similar features. These features help you to: •Create more impact •Create opportunities for outreach •Save time on administrative task

Using Creative Commons Licenses and Creative Commons Licensed Works

Understanding the difference between collections and derivative works is key to your reuse and adaptation of existing material. It is often useful to create collections and derivative works for educational purposes; for instance, you may wish to compile a collection of articles or adapt an existing educational source to serve as a course text. However, it is not always possible to do both or any, depending on copyright restrictions. This presentation will guide your use and re-use of material that hold a Creative Commons license. In this presentation we will answer the questions What are collections and what are derivative works? We will also provide examples of collections and derivative works, along with providing tools for how to navigate reuse with the adapter\u27s license chart and the license compatibility chart

A NuSTAR observation of the fast symbiotic nova V745 Sco in outburst

The fast recurrent nova V745 Sco was observed in the 3-79 keV X-rays band with NuSTAR 10 days after the optical discovery. The measured X-ray emission is consistent with a collisionally ionized optically thin plasma at temperature of about 2.7 keV. A prominent iron line observed at 6.7 keV does not require enhanced iron in the ejecta. We attribute the X-ray flux to shocked circumstellar material. No X-ray emission was observed at energies above 20 keV, and the flux in the 3-20 keV range was about 1.6 $\times$ 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$. The emission measure indicates an average electron density of order of 10$^7$ cm$^{-3}$. The X-ray flux in the 0.3-10 keV band almost simultaneously measured with Swift was about 40 times larger, mainly due to the luminous central supersoft source emitting at energy below 1 keV. The fact that the NuSTAR spectrum cannot be fitted with a power law, and the lack of hard X-ray emission, allow us to rule out Comptonized gamma rays, and to place an upper limit of the order of 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$ on the gamma-ray flux of the nova on the tenth day of the outburst.Comment: in press in Monthly Notices of the Royal Astronomical Society, 201

N terminus is key to the dominant negative suppression of CaV2 calcium channels: implications for episodic ataxia type 2

Expression of the calcium channels CaV2.1 and CaV2.2 is markedly suppressed by co-expression with truncated constructs containing Domain I. This is the basis for the phenomenon of dominant negative suppression observed for many of the episodic ataxia type 2 mutations in CaV2.1 that predict truncated channels. The process of dominant negative suppression has been shown previously to stem from interaction between the full-length and truncated channels and to result in downstream consequences of the unfolded protein response and endoplasmic reticulum-associated protein degradation. We have now identified the specific domain that triggers this effect. For both CaV2.1 and CaV2.2, the minimum construct producing suppression was the cytoplasmic N terminus. Suppression was enhanced by tethering the N terminus to the membrane with a CAAX motif. The 11-amino acid motif (including Arg52 and Arg54) within the N terminus, which we have previously shown to be required for G protein modulation, is also essential for dominant negative suppression. Suppression is prevented by addition of an N-terminal tag (XFP) to the full-length and truncated constructs. We further show that suppression of CaV2.2 currents by the N terminus-CAAX construct is accompanied by a reduction in CaV2.2 protein level, and this is also prevented by mutation of Arg52 and Arg54 to Ala in the truncated construct. Taken together, our evidence indicates that both the extreme N terminus and the Arg52, Arg54 motif are involved in the processes underlying dominant negative suppression