Ameboid Movement and Related Phenomenal

Mechanical transformations of living cavitary bodies

“…Bereiter-Hahn and Lüers (1998) found a weakening of the connections between cortical filaments and the peripheral plasmalemma in lamellipodia of keratocytes. The destruction of the cortex or its detachment from the membrane was observed at the leading edge of moving cells (Stossel, 1993), during formation of evaginations in amoebae (Stockem and Kłopocka, 1988;Grębecki, 1990), Dictyostelium (Merkel et al, 2000;Yoshida and Inouye, 2001), the protist Vampyrella lateritia (Hüls-mann and Grębecki, 1995), macrophages, astrocytes and thyroid cells (see Grębecki, 1994). It seems that only Keller and Eggli (1998) contradistinguished lamellipodia and blebs indicating that in carcinosarcoma cells the association between the plasmalemma and the cortex did not loosen at the edge of lamellipodia.…”

“…Parts of the tail sheath get inside the cell by intensive endocytosis (pinocytosis). The flow of endoplasm transports this material to the evaginating edges where it is used for the construction of new sheath areas (Stockem and Kłopocka, 1988). This means that the cytoplasmic flow plays the key role in locomotion and pseudopodial growth, exercising the mechanical impact on the plasmalemma and delivering the building material.…”

“…It has been suggested, for instance, that the weakening of the evaginating apical sheath occurs as a result of the destruction of the cortex or its detachment from the plasmalemma (Stockem, Kłopocka, 1988;Grębecki, 1990). We also know now that the cortex of a moving amoeba is periodically destroyed not only at the leading edge but also at the posterior end (Stockem and Kłopocka, 1988). However, the nature of the cytoplasmic flow largely remains a mystery.…”

“…There is an opinion that the circulation indeed occurs: while the central part of the cytoplasm (the endoplasm) is flowing forward, its peripheral layer (the ectoplasm) is moving backwards. This phenomenon is referred to as the fountain streaming (Stockem and Kłopocka, 1988). I said "opinion", not observation, and I mean it.…”

Characterization of Amoeba proteus myosin VI immunoanalog

“…It locomotes almost 500 times faster than mammalian fibroblasts and contains a large amount of vesicles, granules, and vacuoles that move back and forth with a speed comparable to that of the entire cell locomotion. This trafficking is based solely on the actin cytoskeleton as amoebae do not form cytoplasmic microtubules during interphase [Stockem and Kłopocka, 1988]. While there is a substantial amount of data regarding the structure and regulation of the actin-based cytoskeleton of Acanthamoeba castellanii and Dictyostelium discoideum (these cells are nota bene ten to twenty times smaller than A. proteus), there is very little information on the molecular nature of the actin-based system of Amoeba proteus [for references see Jeon, 1995;Oh and Jeon, 1998].…”