INVESTIGADORES
VALENTINUZZI veronica Sandra
congresos y reuniones científicas
Título:
Photic synchronization and photoperiodic time measurement in subterranean rodents (Ctrenomys Knightii)
Autor/es:
FLORES DANILO EFL; VALENTINUZZI VERÓNICA S; ODA GISELE A
Lugar:
Natal, RN, Brazil
Reunión:
Simposio; X Latin American Symposium on Chronobiology; 2009
Institución organizadora:
Universidade Federal do Rio Grande do Norte-Brasil
Resumen:
The aim of our research is to investigate the mechanism of light/dark entrainment and photoperiodic time measurement in the solitary subterranean rodent Ctenomys knighti (tuco-tuco). Subterranean animals are interesting systems for the study of synchronization, because they spend most of their time underground in rather constant conditions. For this investigation, we intend to make a PRC in the laboratory and complete the study with field measurements on the temporal profiles of light exposure. These measurements will cover both the daily and annual scales. For the laboratory part, 15 animals in cages with running-wheels are being assayed for their activity-rest rhythm. After synchronization to LD 12:12, they were submitted to constant dim light in order to get free-running rhythms and then given 15 minutes light pulses (200 lux) covering 8 equally spaced phases within a circadian period. The field part of the study consists in recording the activity-rest rhythm and light exposure events of 5 animals maintained in their own burrow systems and equipped with an actigraph-luximeter device. Our main question is whether and to what extent the synchronization in the field, if it happens, may be explained by a nonparametric entrainment in the tuco-tuco clocks, as can be predicted from the PRC. Assuming that tuco-tucos expose themselves to light during short and few episodes per day, computer simulations will be performed to study entrainment by random light pulses, all concentrated in the light phase of the day. Computer simulations will help understanding how this kind of entrainment is dependent on the shape of the PRC and our experimental and particular PRC shape is going to be analyzed in this context. In future studies, we intend to use the field data to investigate a possible seasonal variation in the activity-rest rhythm. Could tuco-tucos, like other species, present shortening and lengthening of their daily activity phase accompanying yearly changes in photoperiod, despite living in a fairly constant micro-environment?. If the tuco-tucos’ activity rhythms show seasonal variations, we are going to investigate how these animals can measure photoperiod by random and few light pulses per day. Our hypothesis is that if photoperiodic measurement occurs, it is achieved by the external coincidence mechanism in subterranean organisms.