Cloe Taddei-Ferretti

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It has been hypothesized that the mechanism responsible for the rhythmic contraction-relaxation activity of Hydra attenuata is oscillatory. This nature is confirmed by the possibility of obtaining the suppression of overt behaviour by high frequency photic stimulation, which entrains the behaviour at a phase different from that giving rise to overt(More)
The cnidarian Hydra does not possess identified photoreceptive structures or specialized cells for light detection; nevertheless, it shows a marked photosensitivity. So far no evidence has been previously reported about the localization of the proteins involved in the photoresponse. We used polyclonal antibodies and immunofluorescence microscopy on(More)
The morpho-functional organization correlated to photosensitivity in Cnidaria is that of ocelli and extraocular photoreception. Several examples of the second type of organization are reported. The photosensitivity of the cnidarian Hydra is of the extraocular (neural or dermal) type. The effects of photic stimulation (applied according to various(More)
We investigated in Hydra attenuata the possibility of altering more or less permanently and in different environmental conditions, the frequency of Contraction Pulse Trains (CPT's) associated with the rhythmic spontaneous contraction activity, by repetitive light stimuli of variable duration, frequency and amplitude. The CPT's activity of various pieces of(More)
1. The behaviours of monocular and binocular flies are compared with respect to the landing reaction. It is found that landing reaction is elicited through different mechanisms by stimulating the zones of single or of double vision: M onocular stim ulation in the field of single vision evokes reactions with both ipsilateral and contralateral legs; monocular(More)
We investigated the effect of photic stimulation on the frequency of Hydra attenuata column contractions. We used positive or negative abrupt light transitions, single or repetitive light or darkness pulses, and alternation of light and darkness periods. The main results are: (a) The frequency of the contraction pulse trains (CPTs) varies transiently in(More)
mals, p. 412 (Busnel, R.G., ed.). New York: Elsevier 1963 4. Bailey, W.J., Thompson, P.: J. Exp. Biol. 67, 61 (1977) 5. Murphey, R.K., Zaretsky, M.D.: ibid. 56, 335 (1972) 6. Larsen, O.N., Michelsen, A.: J. Comp. Physiol. 123, 217 (1978) 7. Moiseff, A., Pollack, G.S., Hoy, R.R. : Proc. Nat. Acad. Sci. USA 75, 4052 (1978) 8. Hill, K.G., Boyan, G.S. : J.(More)
Spontaneous figure reversal of ambiguous patterns was analyzed in humans. A) With Necker-"cube"-like, or "drum"-like figures, having square or round shaped "front" and "rear" surfaces, and either large or small "depth", the perceptual intervals corresponding to both interpretations of "drum" were longer than those of "cube"; the perceived "depth" of the(More)
Hydra’s response to a light pulse is a phase shift of the state of bioelectric activity correlated with the periodic shortening-elongation behaviour. The direction and absolute value of a phase shift depend on intensity, direction, application phase (along the periodic activity state), and wavelength of the light pulse. Repetitive pulses entrain the(More)