Two years have passed since last Limb meeting, which took place in Edinburgh. This year’s conference was hosted by EMBL Barcelona, located in the Barcelona Biomedical Research Park. James Sharpe (EMBL Barcelona) together with Marian Ros (CSIC-SODERCAN) and Miguel Torres (CNIC) organized a four-day meeting bringing together experts in the field of Limb Development.
The conference was divided in five specialized areas (Gene Regulation, Patterning and Regeneration, Morphogenesis and Modelling, Growth and Evolution), and hosted almost fifty talks and two poster sessions (including 64 posters).
Thanks to genome editing (CRISPR/CAS9), human mutations can be introduced in mice to understand the molecular interactions that give rise to limb-related diseases such as polydactyly or Nail-Patella Syndrome (NPS). Len Pennacchio and Kerby Oberg presented their work on this topic.
Single cell transcriptomics techniques are being used to investigate cell fate determination and differentiation in a spatio-temporal fashion during limb development and regeneration.
Patterning and Regeneration
During development, diffusible signals (morphogens) are known to generate gradients that pattern cells along embryonic axes. Nevertheless, since cells from the limb are in constant rearrangement over space and time during development and regeneration, the signalling pathways coupled with morphogen interactions are not completely understood at every embryological stage. Irene Delgado (CNIC, Madrid), Malcom Logan (King’s College London, UK) and Elly Tanaka (Research Institute of Molecular Pathology, Austria) gave some insights on this topic.
Morphogenesis and Modelling
During limb development, cells are exposed to constant molecular signalling but also cell interactions, tissue rearrangements, movement and mechanics. Thanks to improved imaging techniques and computer modelling, we have a better understanding of how cells interact with each other in order to shape the limb. Highlighted talks by Paula Murphy (Trinity College Dublin, Ireland), Jerome Gros (Institute Pasteur, France) and Miquel Marin-Riera (EMBL, Spain) summarized perfectly this section.
Cell proliferation and organisation are involved in tissue growth in order to pattern and shape bigger structures such as organs and later on full organisms. How proportions are maintained during these processes is still unknown.
Hanh Nguyen (CNRS, France) talked about using imaging techniques to achieve cell linage reconstruction of pectoral fin from Zebrafish at very early stages (28 to 48 hours post fertilization), exactly when embryos grow from 2D to 3D tissues during development.
Neil Vargesson (University of Aberdeen, UK) talked about how Thalidomide, a drug used to deal with nauseas in pregnant women during 1957 that produced limb malformations (phocomedia) to new-borns, affects limb development by avoiding the proper formation of the vascular system during limb development.
Fin to limb transition it has always been an intriguing question from an evolutionary point of view. Joost Woltering (University of Konstanz, Germany) investigates genetic markers for the anterior-posterior and proximo-distal axis of the lung fish fins, which are anatomically very different from the ray-finned fish and closer to the tetrapods.
Other scientists such as Karen Sears (University of California, Los Angeles) and Kimberly Cooper (University of California, San Diego) focused their research in using mammals with different limb morphologies such as bats and bipedal jerboa Jaculus jaculus to understand the regulatory changes in the genome of these species in the evolution of gene expression and limb morphology.
The poster sessions were a success and around 20 scientists presented their research in flash talks.
Science is evolving fast thanks to new techniques and this year’s Limb meeting was at the forefront of it discussing projects related to CRISPR/Cas9, single cell transcriptomics and live imaging.