title: Circadian rhythms and time measurement in locomotor activity of the scorpion Leiurus quinquestriatus (Buthidae).
abstract: The circadian rhythms of locomotor activity of the scorpion Leiurus quinquestriatus were examined under different light-dark cycles and in free-running conditions. The circadian rhythm is bimodal in LD 12:12 with alternating cycles of temperature (35 degrees-25 degrees C) with high intensity (1300 lux) or in LD 12:12 with constant temperature 35 degrees C with 300 lux. In LD 12:12 (1300 lux), in long or in short light spans with constant temperature, the bimodal pattern is slightly changed with the appearance of a third minor peak of activity. In free-running conditions, the bimodal rhythm of locomotor activity persists in DD with T about 24 hr, but in LL the rhythm becomes unimodal with T about 24 hr. Cosinor and power spectrum analysis showed the presence of more than one periodic component. It seems that there is a correlation between the range of light regimens, temperature, light intensity and the coincidence of these components. These components are independently entrained by the environmental light cycle. The mechanism of entrainment of components is discussed.
authors.affiliation: Laboratoire de Biologie de l'Insecte, Université de Paris-Sud, Orsay, France.
authors.forename: Z
authors.initials: Z
authors.lastname: el Bakary
authors.forename: S
authors.initials: S
authors.lastname: Fuzeau-Braesch
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D009043:Motor Activity; D012605:Scorpions / Q000502:physiology*; D013696:Temperature