Minipodia and rosette contacts are adhesive organelles present in free-living amoebae.
Using scanning electron microscopy, Amoeba proteus cells migrating on the glass have been shown to develop dense coats of minipodia, which are discrete microprotrusions up to 8 microm long and approximately 0.5 microm across. They cover the middle-anterior area of the ventral cell surface, i.e. the region previously determined as the zone of most efficient adhesion of an amoeba to its substratum. Minipodia are sparse underneath the frontal zone and lacking from the tail region. In amoebae that adhere to the glass without moving, have just started moving, or show unstable motor polarity, minipodia are grouped in rosette contacts, cauliflower-like papillae composed of supporting platforms with crowns of minipodia emerging from them. Both structures abound with cytoskeletal F-actin, as shown by staining with fluorescein-conjugated phalloidin. Amoebae experimentally prevented from adhering to the substratum neither develop discrete minipodia nor rosette contacts.
Grebecki
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Department of Cell Biology, Nencki Institute of Experimental Biology, Warszawa, Poland. grebecki@nencki.gov.pl
Grebecka
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Wasik
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D000656:Amoeba / Q000648:ultrastructure*; D000818:Animals; D002478:Cells, Cultured; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D015388:Organelles / Q000648:ultrastructure*; D010587:Phagocytosis / Q000502:physiology; D012397:Rosette Formation