Restoration of morphological and functional integrity in the regenerating eye of the giant African land snail Achatina fulica

Abstract

 Abstract Bobkova, M.V., Tartakovskaya, O.S., Borissenko, S.L., Zhukov, V.V. & Meyer-Rochow, V.B. 2004. Restoration of morphological and functional integrity in the regenerating eye of the giant African land snail Achatina fulica . -Acta Zoologica (Stockholm) 85 : 1-14To determine whether vision returns to its original state following eye removal in Achatina fulica , light and electron microscope examinations, electrophysiological recordings and behavioural tests were carried out on the regenerating snails. Reparative morphogenesis can result in the restoration of the peripheral sense organ even in the absence of complete regrowth of the tentacle, but it can also lead to the formation of aberrant regenerates. We found that anatomically and ultrastructurally the eyes of the 'most normal' regenerates were basically the same as the original eyes. Under normal conditions each eye is composed of a principal and an accessory eye, both sharing a common cornea. The only difference between regenerated and native eyes is the smaller size of the former, as a result of a reduced number of retinal cells. Electroretinographic responses revealed that the molecular mechanism of phototransduction is restored, in principle, but that flicker fusion frequency in the regenerated eye is significantly lower than in the normal eye. The directional movement to a visual stimulus (a black stripe of 45 ° width) had not completely recovered even 6 months after amputation. This suggests that the central projections of the optic nerve had not become fully re-established at the time of testing.

Eyes and vision in Arion rufus and Deroceras agreste (Mollusca; Gastropoda; Pulmonata): What role does photoreception play in the orientation of these terrestrial slugs?

“…The mean vector of movement was determined as a segment of the straight line between the centre of the tank bottom and the point of the tank wall that the test animal reached. Values of ‘ U ’, describing the deviation of animals from the predicted direction ‘ U crit ’ were calculated according to Bobkova et al . (2004b) and to determine statistical significance the ‘Table of Significance’ ( P = 0.05) in Batschelet (1972) was used.…”

Regional expression of neuropeptides in the retina of the terrestrial slug Limax valentianus (Gastropoda, Stylommatophora, Limacidae)

“…The cells in the retina of terrestrial slugs and snails consist of two types of photoreceptor cells (Type-I and Type-II photoreceptors), supportive pigment cells, and ganglion cells, according to the morphological characteristics (Bobkova et al, 2004;Brandenburger, 1975;Katagiri et al, 2001;Kataoka, 1975). Based on our present immunohisto- axons projecting to the brain (Brandenburger, 1975;Kataoka, 1975).…”

“…The cells in the retina of terrestrial slugs and snails consist of two types of photoreceptor cells (Type‐I and Type‐II photoreceptors), supportive pigment cells, and ganglion cells, according to the morphological characteristics (Bobkova et al., 2004; Brandenburger, 1975; Katagiri et al., 2001; Kataoka, 1975). Based on our present immunohistochemical and in situ hybridization experiments, it is difficult to determine which type of cells express the neuropeptides examined in this study due to the limitation in the spatial resolution.…”

A flashing light may not be that flashy: A systematic review on critical fusion frequencies

“…Reported values of CFF varied from a maximum of between 300 Hz and 500 Hz for the beetle Melanophila acuminata D. [56] to a mean (± SD) of 0.57 (± 0.08) Hz for the snail Lissachatina fulica B. [57].…”