Making sense of zebrafish neural development in the Minervois

The meeting 'From sensory perception to motor output: genetic bases of behavior in the zebrafish embryo' was held at Minerve (South of France) on March 16–18, 2007. The meeting site was beautifully situated in the heart of the Minervois wine country, and its remoteness promoted conversations and interaction over the course of the program. The meeting covered neurogenesis and eye development on day 1, ear and lateral line development on day 2, and brain connectivity and behavior on day 3. Underlying all sessions, however, ran the growing importance of live imaging, an approach that takes full advantage of the transparency of fish embryos and early larvae, as illustrated by several movies and links in this report

Control of cell migration in the development of the posterior lateral line: antagonistic interactions between the chemokine receptors CXCR4 and CXCR7/RDC1

BACKGROUND: The formation of the posterior lateral line of teleosts depends on the migration of a primordium that originates near the otic vesicle and moves to the tip of the tail. Groups of cells at the trailing edge of the primordium slow down at regular intervals and eventually settle to differentiate as sense organs. The migration of the primordium is driven by the chemokine SDF1 and by its receptor CXCR4, encoded respectively by the genes sdf1a and cxcr4b. cxcr4b is expressed in the migrating cells and is down-regulated in the trailing cells of the primordium. sdf1a is expressed along the path of migration. There is no evidence for a gradient of sdf1a expression, however, and the origin of the directionality of migration is not known. RESULTS: Here we document the expression of a second chemokine receptor gene, cxcr7, in the migrating primordium. We show that cxcr7 is highly expressed in the trailing cells of the primordium but not at all in the leading cells, a pattern that is complementary to that of cxcr4b. Even though cxcr7 is not expressed in the cells that lead primordium migration, its inactivation results in impaired migration. The phenotypes of cxcr4b, cxcr7 double morphant embryos suggest, however, that CXCR7 does not contribute to the migratory capabilities of primordium cells. We also show that, in the absence of cxcr4b, expression of cxcr7 becomes ubiquitous in the stalled primordium. CONCLUSION: Our observations suggest that CXCR7 is required to provide directionality to the migration. We propose that directionality is imposed on the primordium as soon as it comes in contact with the stripe of SDF1, and is maintained throughout migration by a negative interaction between the two receptors

The transmembrane inner ear (tmie) gene contributes to vestibular and lateral line development and function in the zebrafish ( Danio rerio )

The inner ear is a complex organ containing sensory tissue, including hair cells, the development of which is not well understood. Our long-term goal is to discover genes critical for the correct formation and function of the inner ear and its sensory tissue. A novel gene, transmembrane inner ear ( Tmie ), was found to cause hearing-related disorders when defective in mice and humans. A homologous tmie gene in zebrafish was cloned and its expression characterized between 24 and 51 hours post-fertilization. Embryos injected with morpholinos (MO) directed against tmie exhibited circling swimming behavior (∼37%), phenocopying mice with Tmie mutations; semicircular canal formation was disrupted, hair cell numbers were reduced, and maturation of electrically active lateral line neuromasts was delayed. As in the mouse, tmie appears to be required for inner ear development and function in the zebrafish and for hair cell maturation in the vestibular and lateral line systems as well. Developmental Dynamics 237:941–952, 2008. © 2008 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58082/1/21486_ftp.pd

Etude des mécanismes de régulation positive chez le bactériophage lambda

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Imagerie et développement de la ligne latérale chez le Poisson-zèbre

Le système de la ligne latérale du Poisson-zèbre présente les qualités de simplicité, d’accessibilité et de reproductibilité qui en font un système approprié pour l’analyse du développement neural et la formation d’un « modèle » chez les Vertébrés. De plus, la transparence de l’embryon permet l’utilisation, chez l’animal vivant, d’une batterie d’outils optiques et moléculaires, essentiels pour une analyse approfondie du système

The determination of sense organs in Drosophila: A search for interacting genes

The determination of sense organs in Drosophila requires the concerted action of a battery of genes, several of which have been identified. Previous experiments revealed that flies doubly heterozygous for mutations in two of these genes have a reduced number of sense organs, suggesting the existence of a direct interaction between the corresponding genes and/or their products. We have now used this observation to search for mutations in additional genes that would show similar interactions. We have detected 10 recessive mutations that show a dominant reduction in the number of bristles when simultaneously heterozygous for either Df(2)J27 or Df(4)M62f. Among these mutations, 3 are homozygous viable and show striking defects in their bristle patterns, confirming that the genes thus identified play a role in the patterning of sense organs. We conclude that the 'gene dose titration' method (Botas et al. 1982) is an efficient method for identifying interacting genes involved in a common process, provided one can identify a well-defined phenotype to look at, and at least one mutation that alters the process. Our experience suggests that its efficiency should be substantially improved by the use of insertional mutagenesis.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Le développement du système nerveux: de la mouche au poisson, du poisson à l’homme…

Le système nerveux des vertébrés est bien plus complexe, et moins facile d’approche, que celui d’organismes modèles comme la mouche et le nématode. Dans cet article, nous présentons un système sensoriel de vertébré de structure simple, accessible à l’expérimentation, et approprié pour une étude génétique: la ligne latérale du poisson zèbre. Notre travail récent sur le développement de ce système a mis en évidence le rôle majeur joué par les migrations cellulaires et nous a permis de montrer que certains des facteurs contrôlant ces migrations sont semblables aux facteurs responsables de la formation de métastases dans certains types de cancers humains. Ce parallélisme illustre une fois de plus la remarquable conservation des mécanismes du développement et des gènes qui les sous-tendent dans tout le règne animal.The nervous system of vertebrates is more complex and less tractable than that of current model organisms such as the fly and the nematode. Here we present a vertebrate sensory system which is structurally simple, experimentally accessible and genetically suitable: the lateral line of the zebrafish. We review our recent work on the development of this system, with a particular emphasis on the migration events that shape the pattern of sense organs. Some of the factors involved in these migration events turn out to be similar to the factors that direct the formation of metastases in specific types of human cancers, illustrating once again the remarkable conservation of developmental mechanisms and genes throughout the animal kingdom

A minor Q-independent pathway for the expression of the late genes in bacteriophage λ

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Genesis of the Drosophila peripheral nervous system

SCOPUS: re.jinfo:eu-repo/semantics/publishe