Strabismus-mediated primary archenteron invagination is uncoupled from Wnt/β-catenin-dependent endoderm cell fate specification in Nematostella vectensis (Anthozoa, Cnidaria): Implications for the evolution of gastrulation

<p>Abstract</p> <p>Background</p> <p>Gastrulation is a uniquely metazoan character, and its genesis was arguably the key step that enabled the remarkable diversification within this clade. The process of gastrulation involves two tightly coupled events during embryogenesis of most metazoans. Morphogenesis produces a distinct internal epithelial layer in the embryo, and this epithelium becomes segregated as an endoderm/endomesodermal germ layer through the activation of a specific gene regulatory program. The developmental mechanisms that induced archenteron formation and led to the segregation of germ layers during metazoan evolution are unknown. But an increased understanding of development in early diverging taxa at the base of the metazoan tree may provide insights into the origins of these developmental mechanisms.</p> <p>Results</p> <p>In the anthozoan cnidarian <it>Nematostella vectensis</it>, initial archenteron formation begins with bottle cell-induced buckling of the blastula epithelium at the animal pole. Here, we show that bottle cell formation and initial gut invagination in <it>Nematostella </it>requires NvStrabismus (NvStbm), a maternally-expressed core component of the Wnt/Planar Cell Polarity (PCP) pathway. The NvStbm protein is localized to the animal pole of the zygote, remains asymmetrically expressed through the cleavage stages, and becomes restricted to the apical side of invaginating bottle cells at the blastopore. Antisense morpholino-mediated NvStbm-knockdown blocks bottle cell formation and initial archenteron invagination, but it has no effect on Wnt/ß-catenin signaling-mediated endoderm cell fate specification. Conversely, selectively blocking Wnt/ß-catenin signaling inhibits endoderm cell fate specification but does not affect bottle cell formation and initial archenteron invagination.</p> <p>Conclusions</p> <p>Our results demonstrate that Wnt/PCP-mediated initial archenteron invagination can be uncoupled from Wnt/ß-catenin-mediated endoderm cell fate specification in <it>Nematostella</it>, and provides evidence that these two processes could have evolved independently during metazoan evolution. We propose a two-step model for the evolution of an archenteron and the evolution of endodermal germ layer segregation. Asymmetric accumulation and activation of Wnt/PCP components at the animal pole of the last common ancestor to the eumetazoa may have induced the cell shape changes that led to the initial formation of an archenteron. Activation of Wnt/ß-catenin signaling at the animal pole may have led to the activation of a gene regulatory network that specified an endodermal cell fate in the archenteron.</p

An Asphalt Emulsion Modified by Compound of Epoxy Resin and Styrene-Butadiene Rubber Emulsion

Abstract-A modified asphalt emulsion with superior performances will be produced after compound of waterborne epoxy resin and styrene-butadiene rubber are mixed in emulsified asphalt. This paper describes the method and technique for preparation of the material as well as the test and research on aspects like adhesion, various performances of evaporation residues and durability, and the results from which reveal that this modified asphalt emulsion shows road performances and indexes better than those of ordinary asphalt emulsion and asphalt emulsion modified by styrene-butadiene rubber latex and will find application in engineering

Congestion behavior and tolls in a bottleneck model with stochastic capacity

In this paper we investigate a bottleneck model in which the capacity of the bottleneck is assumed stochastic and follows a uniform distribution. The commuters’ departure time choice is assumed to follow the user equilibrium principle according to mean trip cost. The analytical solution of the proposed model is derived. Both the analytical and numerical results show that the capacity variability would indeed change the commuters’ travel behavior by increasing the mean trip cost and lengthening the peak period. We then design congestion pricing schemes within the framework of the new stochastic bottleneck model, for both a time-varying toll and a single-step coarse toll, and prove that the proposed piecewise time-varying toll can effectively cut down, and even eliminate, the queues behind the bottleneck. We also find that the single-step coarse toll could either advance or postpone the earliest departure time. Furthermore, the numerical results show that the proposed pricing schemes can indeed improve the efficiency of the stochastic bottleneck through decreasing the system’s total travel cost

An agent-based approach to assess drivers’ interaction with pre-trip information systems.

This article reports on the practical use of a multi-agent microsimulation framework to address the issue of assessing drivers’ responses to pretrip information systems. The population of drivers is represented as a community of autonomous agents, and travel demand results from the decision-making deliberation performed by each individual of the population as regards route and departure time. A simple simulation scenario was devised, where pretrip information was made available to users on an individual basis so that its effects at the aggregate level could be observed. The simulation results show that the overall performance of the system is very likely affected by exogenous information, and these results are ascribed to demand formation and network topology. The expressiveness offered by cognitive approaches based on predicate logics, such as the one used in this research, appears to be a promising approximation to fostering more complex behavior modelling, allowing us to represent many of the mental aspects involved in the deliberation process

A new multi-anticipative car-following model with consideration of the desired following distance

We propose in this paper an extension of the multi-anticipative optimal velocity car-following model to consider explicitly the desired following distance. The model on the following vehicle’s acceleration is formulated as a linear function of the optimal velocity and the desired distance, with reaction-time delay in elements. The linear stability condition of the model is derived. The results demonstrate that the stability of traffic flow is improved by introducing the desired following distance, increasing the time gap in the desired following distance or decreasing the reaction-time delay. The simulation results show that by taking into account the desired following distance as well as the optimal velocity, the multi-anticipative model allows longer reaction-time delay in achieving stable traffic flows

Analysis of road network pattern considering population distribution and central business district.

This paper proposes a road network growing model with the consideration of population distribution and central business district (CBD) attraction. In the model, the relative neighborhood graph (RNG) is introduced as the connection mechanism to capture the haracteristics of road network topology. The simulation experiment is set up to illustrate the effects of population distribution and CBD attraction on the characteristics of road network. Moreover, several topological attributes of road network is evaluated by using coverage, circuitness, treeness and total length in the experiment. Finally, the suggested model is verified in the simulation of China and Beijing Highway networks

Heterogeneous bone-marrow stromal progenitors drive myelofibrosis via a druggable alarmin axis

Functional contributions of individual cellular components of the bone-marrow microenvironment to myelofibrosis (MF) in patients with myeloproliferative neoplasms (MPNs) are incompletely understood. We aimed to generate a comprehensive map of the stroma in MPNs/MFs on a single-cell level in murine models and patient samples. Our analysis revealed two distinct mesenchymal stromal cell (MSC) subsets as pro-fibrotic cells. MSCs were functionally reprogrammed in a stage-dependent manner with loss of their progenitor status and initiation of differentiation in the pre-fibrotic and acquisition of a pro-fibrotic and inflammatory phenotype in the fibrotic stage. The expression of the alarmin complex S100A8/S100A9 in MSC marked disease progression toward the fibrotic phase in murine models and in patient stroma and plasma. Tasquinimod, a small-molecule inhibiting S100A8/S100A9 signaling, significantly ameliorated the MPN phenotype and fibrosis in JAK2V617F-mutated murine models, highlighting that S100A8/S100A9 is an attractive therapeutic target in MPNs.Leimkühler and colleagues demonstrate that mesenchymal stromal progenitor cells are fibro

Plasmonic DNA: Towards Genetic Diagnosis Chips

"Plasmonics and DNA" special issueInternational audienc

The interannual variability of east asian winter monsoon and its relation to the summer monsoon

The interannual variability of East Asian winter monsoon (EAWM) is studied based on a mon- soon intensity index with the data from the NCEP/NCAR reanalysis for the period of 1968- 1997. The results show that both the regional Hadley Circulation along the East Asian coast and the Walker Circulation over equatorial latitudes are more intense in a strong monsoon winter than in a weak monsoon winter. This difference corresponds to the shift of major tropical con- vection centres. In a strong monsoon winter the convection is much enhanced over the maritime continent and reduced over the central Pacific, the situation is reverse in a weak monsoon win- ter. These anomalous heat source distributions force opposite phases of the PNA pattern. It is suggested that the barotropic instability of the extratropical zonal flow, which is associated with the interannual variation of EAWM, is important for the propagation of stationary waves along the route of the PNA pattern. There also seems to be a stationary wave originating over the trop- ical western Pacific which propagates eastward and reaches the central and eastern Pacific dur- ing strong monsoon winters. ' The lag-correlations between the EAWM intensity index and tropical Pacific sea surface tem- perature anomaly (SSTA) indicate that the interannual variability of EAWM is mainly influ- enced by the SST As over the tropical Pacific of the preceding summer. These SST As disappear in the following spring. Generally a cool (warm) sea surface temperature in the tropical central and eastern Pacific corresponds to a strong (weak) EAWM. Thus the processes of tropical ocean-atmosphere interactions are suggested to be the dominant mechanism which influence the interannual variations of EAWM. However, the instability processes at midlatitudes can also cause anomalous winter monsoon, such as the 76/77 and 78/79 winter. On the other hand, the SSTA in the South China Sea has been shown to be influenced mainly by the EAWM and may persist to the following summer. Both the circulation at 850 hPa and the rainfall in China confirm that an anomalous East Asian summer monsoon is closely related to the preceding EAWM

A study of R2 measure under the accelerated failure time models

For right-censored data the accelerated failure time (AFT) model is an alternative to the commonly used proportional hazards regression model. It is a linear model for the (log-transformed) outcome of interest, and is particularly useful for censored outcomes that are not time-to-event, such as laboratory measurements. We provide a general and easily computable definition of the R2 measure of explained variation under the AFT model for right-censored data. We study its behavior under different censoring scenarios and under different error distributions; in particular, we also study its robustness when the parametric error distribution is misspecified. Based on Monte Carlo investigation results, we recommend the log-normal distribution as a robust error distribution to be used in practice for the parametric AFT model when the R2 measure is of interest. We apply our methodology to an alcohol consumption during pregnancy data set from Ukraine