Behavioral rhythms in the lab and acute effect of light and darkness in tucotuco (Ctenomys aff. knighti), a subterranean rodent

YASSUMOTO TI; ODA GA; VALENTINUZZI VS

Sao Paulo

Workshop; International Workshop on Organism-environment interactions: timing, plasticity and metabolic adjustments; 2018

The running wheel is commonly used in rhythm studies assuming that the wheel-running time corresponds to the activity time in nature. However, the tuco-tuco (Ctenomys aff. knighti) is a subterranean rodent which is diurnal in the field and nocturnal in the lab. Because of this peculiarity, our first goal is to verify which are their behaviors in the lab, their distribution throughout the 24 hours, and how much the running wheel activity contributes to the total activity. The second goal is to verify what are the acute effects of light and darkness on their rhythms. 18 adult males and females (150-250g) had their behaviors recorded by cameras. Their running wheel activity, general activity and body temperature were also monitored. They were kept in a LD 12:12 (L = 100 lux) regimen and received light and darkness pulses to verify possible masking effects in their rhythms, going through the same protocol three times: 1) without wheel, 2) with wheel, and 3) with a blocked wheel. Most of animals demonstrated little to no rhythmicity in specific lab behaviors, except for running wheel activity. The wheel activity is also the main component of the general activity that is inhibited by the light pulse, but we found some masking on body temperature rhythm as well. Interestingly, there was a single individual that switched from nocturnal to diurnal when kept without a running wheel, and presented the masking patterns expected for diurnal animals.