organisation - the Instituto Gulbenkian de Ciência

ION DYNAMICS
FACILITY
Ana Catarina Certal Head (until May 2011)
José Feijó Head (from June 2011)
PhD in Cell Biology, Universidade de Lisboa
Post-doc at IGC (C. Certal)
PI of Cell Biophysics and Development (J. Feijó)
Head of Facility since 2010
The Ion Dynamics Facility provides researchers with non-invasive technology for
measuring electric currents and specific ion fluxes in biological systems. We are
equipped with a Scanning Voltage Probe (SVET) and three Ion-Specific Probes
(SIET), all from Applicable Electronics. Both probes are set-up in inverted fluorescence
microscopes with high-resolution CCD cameras allowing the coupling
of real-time electrophysiological measurements with intracellular ion imaging.
In close collaboration with the Cell Imaging Unit, we also provide assistance and
advice for advanced ion imaging using both commercial dyes or genetically-encoded
ion probes. At present we have several projects being developed in plant
development (pollen tube growth), fly development (drosophila oogenesis) and
vertebrate organogenesis (zebrafish fin regeneration).
FACILITY STAFF
Teresa Gomes (Research Technician)
PUBLIC ENGAGEMENT IN SCIENCE
Talks for school students, IGC (April, October, December)
MAJOR PROJECTS AND ACCOMPLISHMENTS
ION DYNAMICS DURING DROSOPHILA OOGENESIS I
In Drosophila the establishment of both the anterior-posterior and dorsal-ventral
axes of the embryo depends on signalling provided by the Tgfa-like ligand
Gurken (Grk). When the oocyte nucleus lies close to the posterior pole of the
oocyte, an unknown signal leads to the repolarisation of the oocyte cytoskeleton.
As a consequence, the oocyte nucleus migrates to an anterior cortical
position where EGF signalling leads to the differentiation of the follicle cells
establishing DV polarity. Ion currents have been associated with processes that
contribute to the establishment of polarity in several biological systems. The
aim of this project is to determine if ion dynamics contribute to microtubule repolarisation
in Drosophila early development. Both the SIET technique to measure
ion fluxes and the SVET technique to measure total current are being used
in a histone-GFP line, on egg chambers during stages 4, 5 and 6 of oogenesis.
ION DYNAMICS DURING DROSOPHILA OOGENESIS II
With the results from the project developed by the group of Evolution and
Development we are measuring ion fluxes in 3 lines of histone-GFP Gurken mutant
egg chambers during stages 4, 5 and 6. Both techniques are used, SIET to
measure the ion fluxes and SVET to measure total current.
Ion dynamics as part of the regeneration mechanism of complex organs in vertebrates.
It has long been known that endogenous electric currents and electric
fields are important for vertebrate organ regeneration. Nevertheless, many
questions remain:
1. What is the ion nature of these currents?;
2. How is cellular ion dynamics during the regeneration process?;
3. Which are the molecular signalling pathways that transduce electric cues
into cellular responses?
We use zebrafish caudal fins as an adult regeneration model in vertebrates. Our
approach couples specific extracellular ion flux measurements, carried out using
a non-invasive Scanning Ion-Specific Electrode Technique (SIET), with transcriptional
profiling and genetic functional analysis.
Using SIET we detected dynamic fluxes for potassium (K+), calcium (Ca2+), chloride
(Cl-) and proton (H+) at different stages of the regeneration process. We
are now looking for candidate genes encoding transporters that mediate such
ion-specific fluxes. Microarray analysis revealed the proton pump V-ATPase as a
putative mediator of H+ fluxes. We are validating these data with both genetic
and pharmacological approaches, as well as advanced ion imaging. Overall, our
results suggest tightly-regulated ion-driven phenomena as part of the mechanism
of adult tissue regeneration.
IGC ANNUAL REPORT ‘11
FACILITIES AND SERVICES
95