(This was essentially written by Dr. Chris Gordon – see bottom for details, though “Heather” posted it here.)
Approximately 320 participants attended the second joint meeting of both the Japanese and French societies for developmental biology at the Institut Pasteur on May 26th to 28th, 2010. Of these, sixty Japanese developmental biologists made the voyage to mingle with their French colleagues, drawing on a long-standing and fruitful exchange of scientific trainees and expertise. The Sasakawa Fondation and the Riken Center for Developmental Biology provided lodging for the Japanese participants in Paris, which probably helped with the numbers.
Margaret Buckingham (Institut Pasteur, Paris) and Shinichi Aizawa (Riken Center for Developmental Biology, Kobe), two of the organizers, welcomed all attendees to the conference, entitled “From Cells to Organs”. Each day was divided into two non-concurrent major sessions which were grouped loosely according to theme, and for the first two days, interspersed with two alternate poster sessions. These were so many (168) that even the ample time allotted during coffee breaks, daily catered buffet lunches and evening wine and cheese did not seem to be enough to do them justice. Full presentation abstracts for both talks and posters are found here.
The oral presentations represented an even balance of junior and senior scientists from near and far, all of whom presented in a perfectly comprehensible, transcultural English.
Overall, diverse models were represented. For the posters, the technical approaches were even more diverse and impressive, but too numerous to summarize. Among the talks, models ranged from engineering (Yoshihiro Morishita [Kyushu University, Fukuoaka]) and mathematical approaches (Kenji Matsuno [Tokyo University of Science, Tokyo] ; Hiroki Nishida [Osaka University, Osaka]; Aki Kimura [National Institute of Genetics, Mishima]) to plants (Alexis Peaucelle [INRA, Versailles]) to a broad variety of invertebrate and vertebrate animal systems. For example, Masaaki Yamaguchi (Kanazawa University, Kanazawa) and Julien Behague (Institut Jacques Monod, Paris) spoke about highly conserved transcription factors in the sand dollar Peronella japonica and the annelid Platynereis dumerilii respectively, the study of which uncover evolutionary implications for body plan homologies among Bilaterian clades. Reiko Kuroda (University of Tokyo, Tokyo) presented work on blastomeric symmetry-breaking in the chiral snail, Lymnaeia stagnalis.
Other highlights from the talks, which were all of an excellent standard and most of which presented at least some unpublished work, are summarized below in no particular order, to represent the flavour of the conference.
Atsuo Kawahara (National Cardiovascular Center Research Institute, Osaka) reported his work on the role of sphingosine-1-phosphate (S1P) signalling in zebrafish heart morphogenesis. From a mutagenesis screen, a mutation was identified in spns2, an S1P transporter, in animals with bifid hearts – a phenotype resembling that previously described for an S1P receptor. Knockdown of spns2, or of a sphingosine kinase, specifically in the extraembryonic yolk syncytial layer, also produced cardia bifida. Kawahara’s elegant genetic manipulations suggest that S1P, released by the yolk, signals to migrating cardiac cells in the embryonic tissue above, ensuring coalescence of cardiac progenitors in the midline. For background, see this publication.
Yuuta Moriyama (University of Tokyo, Tokyo) presented data suggesting that in the medaka mutant Double anal fin (Da), in which externally visible dorsal trunk structures become ventralized, a transposon insertion adjacent to zic1 and zic4 disrupts the function of a somitic enhancer for the zic gene pair. Moriyama’s work indicates that via zic genes, the somite plays a key role in patterning a range of tissues in the dorsoventral trunk axis.
Otoliths are biomineralized crystals attached to cilia within the zebrafish inner ear. Their mass contributes to ciliary deflection, leading to transduction of signals for hearing and balance. Julien Vermot (Institut de Genetique et de Biologie Moleculaire et Cellulaire, Illkirch) has used advanced imaging techniques to shed light on how precursor particles of the otolith accumulate within the cavity of the inner ear. Although random diffusion predominates in the central portion of the cavity, local currents are created by beating cilia near the otoliths at the poles of the cavity, thereby attracting particles to the growing crystal. Also, Vermot demonstrated that normal otolith formation is dependent on these cilia, by laser ablation of cilia or knockdown of their components. For background, see this publication.
Mutations in RPGRIP1L, a gene encoding a ciliary protein, have previously been detected in patients with Joubert and Meckel syndromes. Sylvie Schneider-Maunoury (Université Pierre et Marie Curie, Paris) described her recent analysis of olfactory bulb and telencephalic defects in Rpgrip1l-null mice. Concomitant with ciliary defects in forebrain neuroepithelial cells, the mutant mice display a dorsal expansion of ventral telencephalon domains. Gli3, an effector of Hedgehog signalling, regulates dorsoventral patterning of the anterior telencephalon. Schneider-Maunoury presented data suggesting that the Rpgrip1l-null forebrain phenotype is mediated by a reduction of the repressor form of Gli3.
Another layer of complexity in the transmission of Hedgehog signals was discussed by Pascal Thérond (Institut de Biologie du Developpement et du Cancer, Nice). Using the Drosophila epithelial wing disc as a model, Thérond showed that there are apically- and basolaterally-secreted pools of Hedgehog, with Hedgehog activity from the apical pool extending further into the anterior compartment of the disc than that of the basolateral pool. This long-range apical activity is enhanced by the glypican Dally, an extracellular matrix protein, and by Notum, a hydrolase that releases Dally into the apical lumen. The specific readout in cells receiving Hedgehog may be the result of integration of both apical and basolateral inputs. For more information, see this recent publication.
These last presentations were timely in the light of feature articles from that particular issue of Development and also tied in well with a number of other talks and posters concerning Hedgehog signalling effects.
Among these, Koji Tamura (Tohoku University, Sendai) revisited the contribution of the zone of polarizing activity (ZPA) to digit cartilage. As shown by chick-quail chimera fate-mapping, hindlimb digit IV cartilage is directly derived from the Sonic hedgehog-producing ZPA, whereas in the forelimb, no cartilage comes directly from ZPA cells. Heterotopic grafting experiments demonstrated that hindlimb posterior digit identity can be imposed in the forelimb, but not the converse, and only during a restricted time window. A discussion ensued about digit homologies between theropod dinosaurs and birds, and during the questions, amphibians and mammals.
Yoshiko Takahashi (Nara Institute of Science and Technology, Nara) also used the chick embryo to explore the responsiveness of sub-populations of neural crest cells to environmental signals during their dissemination through the body, using the sympatho-adrenal (SA) sublineage as a model. Takahashi reported that SA cells respond to environmental signals that act first on guidepost tissues which thereby attract the neural crest. Subsequently, while sympathetic precursors remain behind to form ganglia, the adrenal precursors must carry on. SA progenitors are electroporated first with an elegant Tol2 transposon construction that mediates stable transgenesis of GFP expression, a helper plasmid with a transposase, and a tet-on inducible dominant-negative receptor. Upon judicious doxycycline stimulation, signal transduction is interrupted only after the labelled cells arrive at the level of the sympathetic ganglion, and the adrenal precursors no longer colonize their target.
Philippe Herbomel (Institut Pasteur, Paris) presented some exquisite examples of in vivo imaging in zebrafish embryos. Using embryos in which vascular cells were labelled with GFP, Herbomel demonstrated how hematopoietic stem cells arise within the aortic endothelium of the fish, in contrast with amniotes. Individual stem cells bend out from the endothelium, away from the lumen of the aorta, and pinch off. They subsequently pass through the underlying mesenchyme to enter the axial vein and go on to seed caudal hematopoietic tissue. Runx1, a key regulator of the emergence of hematopoietic stem cells, is required for this endothelial to hematopoietic transition. Further details can be found in this recent publication.
On the second day, during the general assembly meeting of the SFBD, its new website (http://www.sfbd.fr/) was launched and introduced by Stephan Zaffran. Douglas Sipp, representing the International Society for Developmental Biology also took the stage to encourage the contribution or support of new ideas relative to improving meeting attendance and participation by developmental biologists around the world, before the next ISDB conference in Cancun, Mexico, in 2013.
The meeting ended on a cheerful note with the distribution of poster awards, chosen with some difficulty among the many worthy possibilities by the members of the organizing committee. Meeting sponsors enabled these prizes to not only be a public honour, but to be attached to some prize money. These went to the following presentations:
Glenda Comai (Schedl group, Nice): Functional study of the role of the novel tumor suppressor gene WTX during mouse embryonic development
Mathieu Gouzi (Grapin-Botton group, Lausanne): Role of Neurogenin3 in migration of pancreatic endocrine cells during development
Benjamin Bonneau (Gillet group, Lyon): Member of Bcl2 family Nrz controls yolk cytoskeleton dynamics via regulation of calcium fluxes during zebrafish early development
Toshihiro Banjo (Ogura group, Sendai): MicroRNA-21 expression triggered by heartbeat contributes to zebrafish cardiac valve formation.
Finally, and importantly, the 2nd joint meeting of the British and French Societies for Developmental Biology will be in Nice, France, (yes, that’s the Côte d’Azur) from 3-6 septembre 2011. (The first was in 2003.) Hope to see you there!
About the authors:
Heather Etchevers is not quite sure what she is when it’s translated into English, but she’s tenured with the INSERM and they let her carry out research. She worked in the same group as Chris until June, 2010, when she moved to the INSERM unit 910 in Marseille, France.