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

Towards An Agriculture Information Ecosystem

Stakeholders of a domain in their day today activities generate information which is a valuable resource. To obtain full value of this information it should reach right people at the right time. To investigate how this can be achieved we developed an information flow model for agriculture domain by mapping information needed by stakeholders to information generated by others using set of aggregation and disaggregation operators. We found majority of information needs of stakeholders can be fulfilled by applying these operators to information produced by some other stakeholders thus creating a direct benefit to encourage sharing information. This information flow model had many similarities to biological ecosystems where nutrient cycles and energy flows are replaced by information flows. Based on this information ecosystem model we are developing a mobile based information system for farmers in Sri Lanka. Like biological ecosystems information ecosystems will also need time to grow and become sustainable

Towards using ICT to Enhance Flow of Information to aid Farmer Sustainability in Sri Lanka

Farmers need information at all stages of the farming life cycle to make optimal decisions. The required information includes not only prior knowledge but also real time (dynamic) information such as market prices and current production levels. Some valuable information needed by the farmers is produced by government organizations and is available in different locations in different formats. Although farmer is the most important stakeholder in agriculture, there has not been much effort to provide the essential information to farmers on a real time basis. This lack of information is creating many difficulties for farmers as they are not being able to make the correct decisions relating to their farming activities. Through field studies we have identified information required by farmers at various stages of the farming cycle and official sources where this information is available. Next we developed an information flow model that connects various information sources to farmers’ information needs. Based on these findings we are now developing a mobile phone based information system to deliver the required information to farmers in real time

Towards using ICT to enhance flow of information to aid farmer sustainability in Sri Lanka

Farmers need information at all stages of the farming life cycle to make optimal decisions. The required information includes not only prior knowledge but also real time (dynamic) information such as market prices and current production levels. Some valuable information needed by the farmers is produced by government organizations and is available in different locations in different formats. Although farmer is the most important stakeholder in agriculture, there has not been much effort to provide the essential information to farmers on a real time basis. This lack of information is creating many difficulties for farmers as they are not being able to make the correct decisions relating to their farming activities. Through field studies we have identified information required by farmers at various stages of the farming cycle and official sources where this information is available. Next we developed an information flow model that connects various information sources to farmers&rsquo; information needs. Based on these findings we are now developing a mobile phone based information system to deliver the required information to farmers in real time.<br /

A resorcinarene for inhibition of Aβ fibrillation.

Amyloid-β peptides (Aβ) fibrillation is the hallmark of Alzheimer's disease (AD). However, it has been challenging to discover potent agents in order to inhibit Aβ fibrillation. Herein, we demonstrated the effect of resorcinarene on inhibiting Aβ fibrillation in vitro via experimental and computational methods. Aβ were incubated with different concentrations of resorcinarene so as to monitor the kinetics by using thioflavin T binding assay. The results, which were further confirmed by far-UV CD spectroscopy and atomic force microscopy, strongly indicated that the higher concentration of resorcinarene, the more effective the inhibition of Aβ fibrillation. A cytotoxicity study showed that when sea urchin embryos were exposed to the resorcinarene, the majority survived due to the resorcinarene low toxicity. In addition, when the resorcinarene was added, the formation of toxic Aβ 42 species was delayed. Computational studies of Aβ fibrillation, including docking simulations and MD simulations, illustrated that the interaction between inhibitor resorcinarene and Aβ is driven by the non-polar interactions. These studies display a novel strategy for the exploration of promising antiamyloiddogenic agents for AD treatments

Towards an agriculture knowledge ecosystem :A social life network for farmers in Sri Lanka

We have developed and successfully trialled a Social Life Network (SLN); a Mobile Based Information System to support farming activities in Sri Lanka. It provides information required to support activities such as crop selection and cultivation planning in the context of farmer, farm location, season and task being performed. The system also provides a facility for farmers to sell farming related products and services to other farmers. The final system architecture evolved through a series of iterative relevance and design cycles based on Design Science Research methodology. In the first relevance cycle we identified farmer information needs, their current decision making patterns, and some possible ways to enhance their decision making process. In the first design cycles we developed the initial prototype to visualise a possible solution and in subsequent cycles a crop ontology to reorganise published crop information that would be queried in context and processes to empower farmers. Next we went through 2 cycles of creating functional prototypes, field testing with farmers and improving these to arrive at the final system. We noted that this system can enhance the flow of information in the agriculture domain by aggregating or disaggregating information produced by some stakeholders to be consumed by others. Based on this observation the overall architecture was reconceptualised as a Digital Knowledge Ecosystem

Autonomous Cell Specification: Overview

Autonomous cell specification is a form of specification in which the developing cell is able to differentiate (express proteins typical of the mature cell) without receiving external signals. This is possible when cytoplasmic determinants (the cytoplasmic regulatory factors necessary for specification) are partitioned into the cell during cleavage.Autonomous cell specification is a form of specification in which the developing cell is able to differentiate (express proteins typical of the mature cell) without receiving external signals. This is possible when cytoplasmic determinants (the cytoplasmic regulatory factors necessary for specification) are partitioned into the cell during cleavage

How to grow a gut: ontogeny of the endoderm in the sea urchin embryo

Gastrulation is the process of early development that reorganizes cells into the three fundamental tissue types of ectoderm, mesoderm, and endoderm. It is a coordinated series of morphogenetic and molecular changes that exemplify many developmental phenomena. In this review, we explore one of the classic developmental systems, the sea urchin embryo, where investigators from different backgrounds have converged on a common interest to study the origin, morphogenesis, and developmental regulation of the endoderm. The sea urchin embryo is remarkably plastic in its developmental potential, and the endoderm is especially instructive for its morphological and molecular responsiveness to inductive cell interactions. We start by examining and integrating the several models for the morphogenetic mechanisms of invagination and tissue elongation, the basic processes of endoderm morphogenesis in this embryo. We next critique the proposed mechanisms of inductive gene regulation in the endoderm that exemplifies a concept of modular transcriptional regulation. Finally, we end with an examination of the current molecular models to explain cell fate determination of the endoderm. Recent progress at the molecular level should soon allow us to explain the seminal experimental observations made in this embryo over a hundred years ago. BioEssays 21:459–471, 1999. © 1999 John Wiley & Sons, Inc