Modulation of ultradian rhythms and fractal dynamics of locomotor activity induced by heat stress and dietary supplementation in Japanese quail

FERNANDEZ, M. E.; CORDOBA, F.V.; ANA GEORGINA FLESIA; PAULA SOFIA NIETO; MARIN, RAUL H.; LABAQUE, M. C.; KEMBRO, J. M.

Simposio; Biological Time Keeping. LXXXV Cold Spring Harbor Symposium on Quantitative Biology; 2021

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Dietary supplementation with thymol (2-isopropyl-5-methylphenol) in quail has potential to alleviate physiological and behavioral consequences of heat stress in a time-dependent manner. However, whether these factors can modulate periodic rhythms and fractal dynamics of behavior remainselusive. Herein we assess the effect of chronic cyclic heat stress (HS) and thymol dietary supplementation on the temporal dynamics of behavior in Japanese quail under a LD 14:10 cycle. Starting at 109 days of age, 12 adult females were fed ad libitum with a diet supplemented with thymol and 12 remained on a control basal diet . Between 120 and 129 days of age, withineach group half remained at the standard temperature (24°C) while the other half was submitted to HS (34°C from 8 to 17h). Locomotor activity was recorded every 0.5s during the last 3 days of experimentation. Complementary, on the last day, all behaviors displayed were recorded between 13:30-14 h. A 4-step wavelet approach was used for detection and characterization of locomotor rhythms. Detrended Fluctuation analysis was used to study autocorrelation (fractal) properties of locomotion. As expected, all birds exhibited synchronized circadian rhythms. Moreover, allbirds under standard temperature and basal diet presented synchronized 12 and 8h ultradian rhythms. However, at these time scales among thymol supplemented animals, synchronization was lower and variation coefficient was higher, associated with ≤80% showing evidence of these rhythms. HS in comparison to standard conditions showed modulation of the acrophaseof 12 h rhythms, higher levels of autocorrelation associated with a smoother and less complex locomotor dynamics, and spent less time performing recreational behaviors (i.e.: dust bathing or spreading wings), suggesting that HS would be a powerful modulator of ultradian rhythms and theautocorrelation (fractality) properties of locomotion. However, thymol was not able to alleviate the effects of HS on the overall temporal dynamics of locomotion, and could even in itself promote ultradian rhythm disruption. These results emphasize the importance of evaluating temporal dynamics when assessing the effects of HS and dietary supplementation on behavior.