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Temperature cycles trigger nocturnalism in the diurnal homeotherm Octodon degus.
Vivanco, Pablo; Rol, Maria Angeles; Madrid, Juan Antonio.
Afiliação
  • Vivanco P; Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, Murcia, Spain.
Chronobiol Int ; 27(3): 517-34, 2010 May.
Article em En | MEDLINE | ID: mdl-20524798
Body temperature regulation within a physiological range is a critical factor for guaranteeing the survival of living organisms. The avoidance of high ambient temperatures is a behavioral mechanism used by homeothermic animals living in extreme environmental conditions. As the circadian system is involved in these thermoregulatory responses, precise phase shifts and even complete temporal niche inversion have been reported. Octodon degus, a mainly diurnal rodent from Chile, has the ability to switch its phase preference for locomotor activity to coincide with the availability of a running wheel. The aims of this work are twofold: to determine whether ambient temperature cycles, with high values during the day and low values at night (HLT(a)), can induce nocturnal chronotypes in degus previously characterized as diurnal; and to learn whether HLT(a) cycles are able to act as a zeitgeber in this dual-phase species. To this end, degus were subjected to 24 h HLT(a) cycles under both 12:12 LD and DD conditions. Two experimental groups were used, one with previous wheel running experience and another naïve group, to study the influence of the thermal cycles and previous wheel running experience on the degus' dual-phasing behavior. Temperature cycles (31.3 +/- 1.5 degrees C during the day and 24.2 +/- 1.6 degrees C at night) induced a 100% nocturnalism in previously diurnal individuals. Indeed, both entrainment with nocturnal phase angle to LD and nocturnal rhythmicity induced by masking were observed. Moreover, HLT(a) cycles acted by masking, confining wheel-running activity to the cooler phase under DD conditions, with the naïve group being more sensitive than the experienced one.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Roedores / Temperatura Corporal / Octodon Limite: Animals País/Região como assunto: America do sul / Chile Idioma: En Revista: Chronobiol Int Assunto da revista: FISIOLOGIA Ano de publicação: 2010 Tipo de documento: Article País de afiliação: Espanha País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Roedores / Temperatura Corporal / Octodon Limite: Animals País/Região como assunto: America do sul / Chile Idioma: En Revista: Chronobiol Int Assunto da revista: FISIOLOGIA Ano de publicação: 2010 Tipo de documento: Article País de afiliação: Espanha País de publicação: Reino Unido