The cytoskeleton of microvilli of leech photoreceptors. A stable bundle of actin microfilaments

The microvilli of leech photoreceptors have diameters in the range of 60-100 nm. Each contains a bundle of microfilaments extending into the photoreceptor soma as a rootlet (Walz 1979 b). Apparent thicknesses of individual filaments are estimated to be 4-5 nm, consonant with those of identified acti...

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Bibliographic Details
Published in:Cell and tissue research 1983-01, Vol.234 (1), p.9-16
Main Authors: BLEST, A. D, DE COUET, H. G, SIGMUND, C
Format: Article
Language:English
Subjects:
Actins - analysis
Animals
Annelida and closely related phyla: sipuncula. Echiura. Nemertinea
Biological and medical sciences
Calcium - pharmacology
Cytoskeleton - ultrastructure
Fundamental and applied biological sciences. Psychology
Invertebrates
Leeches - ultrastructure
Microscopy, Fluorescence
Microvilli - ultrastructure
Photoreceptor Cells - ultrastructure
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Summary:The microvilli of leech photoreceptors have diameters in the range of 60-100 nm. Each contains a bundle of microfilaments extending into the photoreceptor soma as a rootlet (Walz 1979 b). Apparent thicknesses of individual filaments are estimated to be 4-5 nm, consonant with those of identified actin filaments in the basement membranes of blowflies (Blest and De Couet 1983). Frozen sections of leech photoreceptors labelled with antibodies against scallop actin exhibited strong binding to the rootlet region but not to the microvilli, which are destroyed by the severe saponin or acetone extraction needed to permeabilise the preparation. NBD-phallacidin binds strongly but non-specifically to the photoreceptors and does not allow positive identification of F-actin. The cytoskeletons of the microvilli and rootlets are adequately preserved by conventional routines of fixation, and similar results were obtained when retinae were pretreated with either 0.5 mM Ca2+, 10 mM EGTA, 2 mM Ep-475 (a specific inhibitor of thiol proteases) or 2 mM Ep-475 combined with 0.5 mM Ca2+. Unlike the axial cytoskeletons of arthropod photoreceptor microvilli, those of the leech are stable to cellular insult.
ISSN:0302-766X
1432-0878
DOI:10.1007/BF00217398