Some Recent Findings
- Neurula rotation determines left-right asymmetry in ascidian tadpole larvae "Tadpole larvae of the ascidian Halocynthia roretzi show morphological left-right asymmetry. ... We suggest that chemical, and not mechanical, signals from the vitelline membrane promote nodal expression. Neurula rotation is also conserved in other ascidian species."
- Creating 3D digital replicas of ascidian embryos from stacks of confocal images. "During embryonic development, cell behaviors that are tightly coordinated both spatially and temporally integrate at the tissue level and drive embryonic morphogenesis. Over the past 20 years, advances in imaging techniques, in particular, the development of confocal imaging, have opened a new world in biology, not only giving us access to a wealth of information, but also creating new challenges. It is sometimes difficult to make the best use of the recordings of the complex, inherently three-dimensional (3D) processes we now can observe. In particular, these data are often not directly suitable for even simple but conceptually fundamental quantifications. This article describes a process whereby image stacks gathered from live or fixed ascidian embryos are digitalized and segmented to produce 3D embryo replicas. These replicas can then be interfaced via a 3D Virtual Embryo module to a model organism database (Aniseed) that allows one to relate the geometrical properties of cells and cell contacts to additional parameters such as cell lineage, cell fates, or the underlying genetic program. Such an integrated system can serve several general purposes. First, it makes it possible to quantify and better understand the dynamics of cell behaviors during embryonic development, including, for instance, the automatic detection of asymmetric cell divisions or the evolution of cell contacts. Second, the 3D Virtual Embryo software proposes a panel of mathematical shape descriptors to precisely quantify cellular geometries and generate a 3D identity card for each embryonic cell. Such reconstructions open the door to a detailed 3D simulation of morphogenesis."
- ascidians lack a segmented hindbrain, but have restricted expression patterns of anterior Hox genes.
Alfonso Natale, Carrie Sims, Maria L Chiusano, Alessandro Amoroso, Enrico D'Aniello, Laura Fucci, Robb Krumlauf, Margherita Branno, Annamaria Locascio Evolution of anterior Hox regulatory elements among chordates. BMC Evol. Biol.: 2011, 11;330 PubMed 22085760
| BMC Evol Biol.
Kazuhiko Nishide, Michio Mugitani, Gaku Kumano, Hiroki Nishida Neurula rotation determines left-right asymmetry in ascidian tadpole larvae. Development: 2012, 139(8);1467-75 PubMed 22399684
François B Robin, Delphine Dauga, Olivier Tassy, Daniel Sobral, Fabrice Daian, Patrick Lemaire Creating 3D digital replicas of ascidian embryos from stacks of confocal images. Cold Spring Harb Protoc: 2011, 2011(10);1251-61 PubMed 21969625
A Locascio, F Aniello, A Amoroso, M Manzanares, R Krumlauf, M Branno Patterning the ascidian nervous system: structure, expression and transgenic analysis of the CiHox3 gene. Development: 1999, 126(21);4737-48 PubMed 10518491
Tetsuya Kominami, Hiromi Takata Gastrulation in the sea urchin embryo: a model system for analyzing the morphogenesis of a monolayered epithelium. Dev. Growth Differ.: 2004, 46(4);309-26 PubMed 15367199
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