AMg2+ -dependent class of thick filaments and correlated nuclear chromatin condensation in catfish photoreceptors.
Photoreceptor cells of excised catfish retinae show morphological differences when incubated in Ringer's solutions of varying ionic composition. Two striking changes were observed in photoreceptor cells incubated in a high Mg2+ (25 mM) Ringer's: (1) Thick filaments appeared in the cytoplasm of receptor terminals and myoids; (2) A pronounced condensation of nuclear chromatin occurred in certain nuclei in the outer nuclear layer. The filaments occurred in lattices or bundles. The bundles had a diameter of approximately 0.05--0.2 micrometer and had either tapered or frayed ends. They were observed with somewhat higher incidence in tissue incubated in a 25 mM Mg2+ Ringer's with EGTA added to chelate Ca2+. A common basis for the cytoplasmic and nuclear changes may lie in a redistribution of fibrous protiens brought about by the increased Mg2+ concentration.
D000199:Actins / Q000378:metabolism; D000818:Animals; D002843:Chromatin / Q000187:drug effects*; D005399:Fishes / Q000033:anatomy & histology*; D008274:Magnesium / Q000494:pharmacology*; D008854:Microscopy, Electron; D009218:Myosins / Q000378:metabolism; D009454:Neurofibrils / Q000648:ultrastructure*; D010786:Photoreceptor Cells / Q000378:metabolism / Q000648:ultrastructure*
D000199:Actins; D002843:Chromatin; D009218:Myosins; D008274:Magnesium