endogenous rhythm

endogenous rhythm

a pattern of activity that is controlled from within an organism, rather than from an external stimulus such as the movements of the sun.
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The study tested the new model for entrainment in subtidal crabs, which proposes that the female perceives the environmental cycles and entrains the endogenous rhythm in the embryos.
melanogaster individuals in weak light of the light-dark cycle, and found an oviposition rhythm under 12:12 h L:D conditions, which he held to be the hourglass timing mechanism, not an endogenous rhythm. Many recent studies, however, have found that wild and mutant varieties of fruit flies also display rhythmic oviposition (McCabe & Birley 1998; Sheeba et al.
In grass rats, neurons expressing orexin (ORX) showed a significant daily endogenous rhythm in the expression of Fos that correlated with the rhythm in sleep and wakefulness, and was reversed when compared to that seen in lab rats.
The researchers wrote in Nature, "We have discovered a surprising external cue that helps to optimise this bird's chances of successful migration, and which works in concordance with orientation behaviour and endogenous rhythm to provide precise information about geographical position when such information is crucial.
For the endogenous rhythm to develop in the embryos, it is assumed that the embryos' sensory systems become functional toward the end of development, and the rhythm develops as they entrain to external environmental cycles (Forward, 1987).
argus visual system and testing whether light plays a proximate role in its DVM as an exogenous cue and as an entrainment cue for an endogenous rhythm in vertical migration.
and lighting in the laboratory, females continue to release larvae at specific times, which suggests the presence of an endogenous rhythm in larval release.
Uca crenulata, the California fiddler crab, also has an endogenous rhythm that may be synchronized by tidal cues (Honegger, 1973).
Females with embryos that possessed less than 25% yolk were used to determine the presence of an endogenous rhythm in egg hatching.
Two series of experiments were performed, one testing time of day (TOD) on emergence duration and the other testing for the existence of an endogenous rhythm. In the first series, 100 snails were placed in water-filled trays (see Effects of host inundation) at constant temperature (21[degrees]C) and light (40 [micro]mol/[m.sup.2]/s) for 4 h, starting at a different time each day (0900, 1200, 1500, and 1800).
The period of the endogenous rhythm was about 23.5 h, which is less than 24 h, indicative of a circadian rather than a circatidal clock.