Navegando por Autor "Menezes, Alexandre A. L."
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Artigo Circadian activity rhythm in pre-pubertal and pubertal marmosets (callithrix jacchus) living in family groups(Elsevier, 2016) Melo, Paula R.; Gonçalves, Bruno S. B.; Menezes, Alexandre A. L.; Azevedo, Carolina V. M.In marmosets, a phase advancewas observed in activity onset in pubertal animals living in captivity under seminatural conditions which had stronger correlation with the times of sunrise over the course of the year than the age of the animal. In order to evaluate the effect of puberty on the circadian activity rhythm in male and female marmosets living in family groups in controlled lighting conditions, the activity of 5 dyads of twins (4 ♀/♂and 1 ♂/♂) and their respective parents was continuously monitored by actiwatches between the 4th and 12th months of age. The families were kept under LD 12:12 h with constant humidity and temperature. The onset of puberty was identified by monitoring fecal steroids. Juveniles showed higher totals of daily activity and differences in the daily distribution of activity in relation to parents, in which the bimodal profile was characterized by higher levels in evening activity in relation to morning activity. Regarding the phase, the activity onset and offset, occurred later in relation to parents. After entering puberty, the activity onset and offset occurred later and there was an increase in total daily activity. On the other hand, when assessing the effect of sex, only females showed a delay in the activity offset and an increase in total daily activity. Therefore, the circadian activity rhythmin marmosets has peculiar characteristics in the juvenile stage in relation to the total of daily activity, the onset and offset of the active phase, and the distribution of activity during this phase. Besides, the entering puberty was associated with a phase delay and increase on total daily activity, with differences between sexes, possibly due to hormonal influences and/or social modulation on rhythmArtigo Evidence for age-related changes in the circadian activity rhythm of the diurnal primate Callithrix jacchus: a case report(Taylor and Francis, 2016-01-29) Gonçalves, Fabiana Barbosa; Borges, Galileu R.; Gonçalves, Bruno S. B.; Cavalcante, Jeferson de Souza; Menezes, Alexandre A. L.; Azevedo, Carolina Virginia Macedo deMany cross-sectional studies have shown that circadian rhythms change with age, but such age-related modifications are gradual and may be insufficiently described by cross- sectional studies. In the present case study, circadian activity rhythm (CAR) was evaluated longitudinally, in both LD (12:12) and LL conditions, on two occasions in a single male marmoset: when “adult” (3 y.o.) and when “old” (9 y.o.). When adult, the CAR synchronized with positive phase angles for the onset and offset of activity. In LL, the rhythm free-ran with τ < 24 h. When old, the animal showed a significant phase delay of its activity rhythm with respect to the LD cycle (t-test, p<0.01) and a reduction on total daily activity (t-test, p<0.01), with signs of lesser stability, greater fragmentation and some loss of photic synchronization. In LL, the period free-ran with τ > 24 h. We conclude that aging attenuates photic synchronization and the expression of a circadian activity rhythm in LL in the marmoset. Further studies with a larger number of individuals are needed to confirm these findings