ISSN:
1432-0878
Keywords:
Photoreceptor cells
;
Lysosomes
;
Membrane retrieval
;
Calcium ions
;
Crayfish
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Light-induced degradation of photoreceptor membrane in the crayfish was studied by quantitative light and electron microscopy. The production of lysosomal organelles within the photoreceptor cells was enhanced by presenting the light stimulus intermittently (i.e., flicker) or by doubling its intensity. The enhancement was seen primarily as an increase in the number and size of multivesicular bodies. As these stimulus conditions are likely to facilitate intracellular Ca++ fluxes, the results are compatibl with recent speculations that Ca++ ions may regulate membrane degradation. To test the possibility that Ca++ acts as a signal coupling receptor stimulation with membrane loss, retinas were incubated in the dark with the ionophore A23187 in the presence or absence of external Ca++. The results demonstrate that A23187 produces a Ca++-dependent increase in lysosomal organelles, predominantly multivesicular bodies. These data are consistent with a role for intracellular Ca++ in the degradative process; however, the exact locus of the effect is unclear.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00221869
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