INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Characterization of spontaneous electrical activity in developing spinal motor neurons of zebrafish embryos
Autor/es:
PAOLA V. PLAZAS; NICHOLAAS C SPITZER
Lugar:
San Diego
Reunión:
Congreso; Society for Neuroscience 40th Annual Meeting; 2010
Institución organizadora:
Society for Neuroscience
Resumen:
Calcium signals are key for many processes during
embryonic development. In the nervous system, fluctuations in intracellular
calcium levels play important roles in proliferation, migration and neuronal
differentiation. Moreover, spontaneous calcium transients in embryonic spinal
neurons of X. laevis have been shown
to regulate processes including growth cone motility and neurotransmitter
specification. However, our understanding of the way in which electrical
activity affects the structure and function of developing circuits is still
quite limited.
In this work,
we have taken advantage of the optical transparency and rapid development of
zebrafish (Danio rerio) to study the
patterns of intracellular calcium signals in spinal primary motor neurons (PMN)
of intact embryos during the entire process of axonogenesis, pathfinding and
establishment of early connections.
We
simultaneously tracked axon outgrowth and formation of connections in vivo in transgenic Hb9:eGFP zebrafish
embryos between 16 and 24 hpf and performed calcium imaging with calcium green-1
dextran during pathfinding behavior to determine the timing of electrical
activity. Embryos were paralyzed by exposure to 10 µM a-bungarotoxin. Midtrunk PMN from 16 hpf
(beginning of axon extension) to 24 hpf (when early connections are established
with muscle) displayed spontaneous intracellular calcium transients that are
restricted to single neurons. The calcium transients had an average peak
amplitude of 35 ± 3% above baseline and a duration of 42 ± 2 s. The average
frequency increased from 1.5 ± 0.4 per hour at 16 hpf to 6.2 ± 0.3 per hour at
18 hpf, when axons are reaching the horizontal myoseptum. These results provide
insight into when and where spontaneous electrical activity is expressed
and its relation to the establishment of PMN precise stereotypical axonal
branching patterns. We are now focusing on the activity patterns between 18 and
24 hpf.
Supported by NIH NS15918 to NCS.