Characterization of NvLWamide-like neurons reveals stereotypy in Nematostella nerve net development.

The organization of cnidarian nerve nets is traditionally described as diffuse with randomly arranged neurites that show minimal reproducibility between animals. However, most observations of nerve nets are conducted using cross-reactive antibodies that broadly label neurons, which potentially masks stereotyped patterns produced by individual neuronal subtypes. Additionally, many cnidarians species have overt structures such as a nerve ring, suggesting higher levels of organization and stereotypy exist, but mechanisms that generated that stereotypy are unknown.

Spatiotemporal regulation of nervous system development in the annelid .

Background: How nervous systems evolved remains an unresolved question. Previous studies in vertebrates and arthropods revealed that homologous genes regulate important neurogenic processes such as cell proliferation and differentiation. However, the mechanisms through which such homologs regulate neurogenesis across different bilaterian clades are variable, making inferences about nervous system evolution difficult.

A cell-based model of Nematostella vectensis gastrulation including bottle cell formation, invagination and zippering.

The gastrulation of Nematostella vectensis, the starlet sea anemone, is morphologically simple yet involves many conserved cell behaviors such as apical constriction, invagination, bottle cell formation, cell migration and zippering found during gastrulation in a wide range of more morphologically complex animals. In this article we study Nematostella gastrulation using a combination of morphometrics and computational modeling. Through this analysis we frame gastrulation as a non-trivial problem, in which two distinct cell domains must change shape to match each other geometrically, while maintaining the integrity of the embryo.

Cell-cell adhesion in the cnidaria: insights into the evolution of tissue morphogenesis.

Cell adhesion is a major aspect of cell biology and one of the fundamental processes involved in the development of a multicellular animal. Adhesive mechanisms, both cell-cell and between cell and extracellular matrix, are intimately involved in assembling cells into the three-dimensional structures of tissues and organs. The modulation of adhesive complexes could therefore be seen as a central component in the molecular control of morphogenesis, translating information encoded within the genome into organismal form.

The Hedgehog gene family of the cnidarian, Nematostella vectensis, and implications for understanding metazoan Hedgehog pathway evolution.

Hedgehog signaling is an important component of cell-cell communication during bilaterian development, and abnormal Hedgehog signaling contributes to disease and birth defects. Hedgehog genes are composed of a ligand ("hedge") domain and an autocatalytic intein ("hog") domain. Hedgehog (hh) ligands bind to a conserved set of receptors and activate downstream signal transduction pathways terminating with Gli/Ci transcription factors.

Gastrulation in the cnidarian Nematostella vectensis occurs via invagination not ingression.

Gastrulation is a central event in metazoan development, involving many cellular behaviors including invagination, delamination, and ingression. Understanding the cell biology underlying gastrulation in many different taxa will help clarify the evolution of gastrulation mechanisms. Gastrulation in the anthozoan cnidarian Nematostella vectensis has been described as a combination of invagination and unipolar ingression through epithelial to mesenchymal transitions (EMT), possibly controlled by snail genes, important regulators of EMT in other organisms.

Coordination of microtubule and microfilament dynamics by Drosophila Rho1, Spire and Cappuccino.

The actin-nucleation factors Spire and Cappuccino (Capu) regulate the onset of ooplasmic streaming in Drosophila melanogaster. Although this streaming event is microtubule-based, actin assembly is required for its timing. It is not understood how the interaction of microtubules and microfilaments is mediated in this context.

Genomic inventory and expression of Sox and Fox genes in the cnidarian Nematostella vectensis.

The Sox and Forkhead (Fox) gene families are comprised of transcription factors that play important roles in a variety of developmental processes, including germ layer specification, gastrulation, cell fate determination, and morphogenesis. Both the Sox and Fox gene families are divided into subgroups based on the amino acid sequence of their respective DNA-binding domains, the high-mobility group (HMG) box (Sox genes) or Forkhead domain (Fox genes). Utilizing the draft genome sequence of the cnidarian Nematostella vectensis, we examined the genomic complement of Sox and Fox genes in this organism to gain insight into the nature of these gene families in a basal metazoan.

Rho GTPase function in flies: insights from a developmental and organismal perspective.

Morphogenesis is a key event in the development of a multicellular organism and is reliant on coordinated transcriptional and signal transduction events. To establish the segmented body plan that underlies much of metazoan development, individual cells and groups of cells must respond to exogenous signals with complex movements and shape changes. One class of proteins that plays a pivotal role in the interpretation of extracellular cues into cellular behavior is the Rho family of small GTPases.

Rho1 regulates signaling events required for proper Drosophila embryonic development.

The Rho small GTPase has been implicated in many cellular processes, including actin cytoskeletal regulation and transcriptional activation. The molecular mechanisms underlying Rho function in many of these processes are not yet clear. Here we report that in Drosophila, reduction of maternal Rho1 compromises signaling pathways consistent with defects in membrane trafficking events.

Rho1 interacts with p120ctn and alpha-catenin, and regulates cadherin-based adherens junction components in Drosophila.

Rho GTPases are important regulators of cellular behavior through their effects on processes such as cytoskeletal organization. Here we show interactions between Drosophila Rho1 and the adherens junction components alpha-catenin and p120(ctn). We find that while Rho1 protein is present throughout the cell, it accumulates apically, particularly at sites of cadherin-based adherens junctions.