Departament de Genètica 


Jaume Baguñà
Cristian Cañestro
Jordi Garcia
Pere Martínez
Marta Riutort
Iñaki Ruiz-Trillo
Joan Antoni Vela




1) The origin of bilateral animals, a multigenic approach

The origin of bilateral animals has been debated for more than a hundred years. At the centre of this discussion has been the understanding of mechanisms that would lead the transition from radial to bilateral animals. At the core of most proposals there is a different inferred ancestral bilaterian, either a morphologically simple or a complex animal. During many years, the prevalent view has been that basal bilaterian groups didn’t exist and s complex organism was the better representation of the bilaterian ancestor. But in 1999 Ruiz-Trillo and collaborators suggested the possibility that an ancient group of bilaterians exists with us: the acoel flatworms. This position has been challenged recently by a phylogenomic stud¥ that suggests that acoels are, perhaps, a group of deuterostomes.

In order to understand both the phylogenetic position of these animals and the mechanisms that control their development (plus the relationship between genome structure and development) we have characterized the genes and genomes of two acoels, Symsagittifera roscoffensis and Isodiametra pulchra. From the control of their axis formation to the specification of the tissues, these problems have been dealt with using diverse techniques, from morphology to immunochemistry, molecular biology and genomics.

Dr. Pere Martínez
Dr. Jaume Baguñà

Dr. Marta Chiodin

PhD students
Alexander Alsén
Elena Perea

Dr. Max Telford (University College, London, UK)
Dr. Albert Poustka (Max-Planck Institute of Molecular Genetics, Berlin, Germany)

2) The development of the acoel nervous system

Over the last few years many authors have speculated with the possibility that the acoels have a simple (or simplified) nervous system. The degree of simplicity of this nervous system has, most probably, being exaggerated by some of these authors, who have used for their study only immunochemical methods. We have initiated a program of exhaustive analysis of the structure and development of two acoel nervous systems. Symsagittifera roscoffensis and Isodiametra pulchra. Detailed studies using confocal and electronic microscopy have revealed that the nervous system of the acoels, and the brain, is pretty complex. Currently we are in the process of characterizing a great number of regulatory (transcription factors) and terminal effectors genes (G-protein coupled receptors; GPCRs), using both, bioinformatics procedures plus immunochemistry and in situ hybridization. All of this has been possible thanks to the recent sequencing of the S. roscoffensis genome, a task done by our group and our collaborators.

For the first time we would be able to study the formation of a nervous system of some complexity like that of acoels using the tools of genomics and trancriptomics.

Dr. Pere Martínez

Dr. Marta Chiodin

PhD Student
Elena Perea

Master Student
Brenda Gavilán

3) ParaHox genes involved in echinoderm gut regionalization

Over the last few years we have isolated and characterized a new group of genes with homeobox in the sea urchin Strongylocentrotus purpuratus and the sea star Patiria miniata. This group of genes is used, mostly, in the gut regulating the formation of the different compartments. The ParaHox genes are three, Gsx, Xlox and Cdx. There are homologues of all of them in most bilateral groups and in deuterostomes they are arranged in a genomic cluster. The relative position of the genes within the cluster matches their relative domains along the digestive system. Knowdown experiments have shown that in the absence of Splox and SpCdx the sea urchin gut fails to regionalize. The gene network that controls the specification of the different domains of the gut is being studied now.

We have shown, independently, that the ParaHox genes are not arranged in a cluster in the sea urchin. Strikingly in the genome of the sea star Patiria miniata we have shown that there is a compact genomic cluster. The break of the sea urchin cluster doesn't seem to modify the basic aspects of the expression domain of its constitutive genes. The relative domains of expression for the three ParaHox are maintained in both groups.

Dr. Pere Martínez

Dr. Maria Ina Arnone (Stazione Zoologica, Nàpols, Itàlia)