tailieunhanh - Báo cáo y học: "Fine-scale differences in diel activity among nocturnal freshwater planarias (Platyhelminthes: Tricladida)"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Fine-scale differences in diel activity among nocturnal freshwater planarias (Platyhelminthes: Tricladida). | Lombardo et al. Journal of Circadian Rhythms 2011 9 2 http content 9 1 2 JOURNAL OF CIRCADIAN RHYTHMS RESEARCH Open Access Fine-scale differences in diel activity among nocturnal freshwater planarias Platyhelminthes Tricladida Paola Lombardo Marco Giustini Francesco Paolo Miccoli and Bruno Cicolani Abstract Background Although most freshwater planarias are well known photonegative organisms their diel rhythms have never been quantified. Differences in daily activity rhythms may be particularly important for temperate-climate freshwater planarias which tend to overlap considerably in spatial distribution and trophic requirements. Methods Activity of stress-free individually tested young adults of three common planarian species was recorded at 3-h intervals in a 10-d experiment under natural sunlight and photoperiod during autumnal equinox D L 12 12 . Individual activity status was averaged over the 10-d experiment each tested individual thus serving as a true replicate. Twelve individuals per species were tested. Food was provided every 36 h resulting in alternating day- and nighttime feeding events. Activity during the first post-feeding h was recorded and analyzed separately. Statistical procedures included ANOVAs correlations and second-order analyses of angles. Results Dugesia Girardia tigrina Girard 1850 exhibited clear nocturnal behavior Dugesia Schmidtea polychroa Schmidt 1861 was predominantly but not exclusively nocturnal and Polycelis tenuis Ijima 1884 was relatively more active from midnight through noon. Species-specific activity peaks were statistically similar with peaks at dawn for P. tenuis and just before midnight for the two dugesiids however D. tigrina was comparatively more active in the early night hours while D. polychroa was more active than D. tigrina during daytime. D. tigrina also responded less readily to daytime food addition. P. tenuis remained poorly active and unresponsive throughout the experiment. Individual

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