Microfilaments inNaegleria fowleri amoebae

Abstract

Examination by electron microscopy has revealed 2 types of microfilament in the cytoplasm of 3 strains of axenically grown Naegleria fowleri amoebae. Thin, actin-like microfilaments 5-7 nm in diameter are randomly oriented in the nonmotile amoebae, and are concentrated near the plasma membrane. In the actively motile amoebae these microfilaments aggregate to form colateral bundles in close proximity to the plasma membrane. Thick, myosin-like microfilaments 17-19 nm in diameter also occur in the amoebae cytoplasm. The significance of these 2 kinds of microfilament in amoeboid motion is discussed.

Characterization of proteins in flagellates and growing amebae of Naegleria fowleri

“…Several polypeptide species are abundant in the cell, being present at an estimated concentration of 10' molecules/amebae. Cellular tubulin, for example, makes up about 12% of the total cell protein of Naegleria (9), actomyosin constitutes 0.7% (13), and flagellar tubulin constitutes 0.15% (9). The abundant polypeptides, therefore, are probably structural in nature and might be expected to be relatively stable.…”

5-HMF induces anaphylactoid reactions in vivo and in vitro

“…Coronins are highly conserved actin-binding proteins located in the frontal regions of motile cells [ 41 ]. Actin fibers, also known as microfilaments (MF), are spiral fibers composed of cytoskeleton actin, with a diameter of 5–7 nm [ 42 ]. Therefore, we also assessed the cytoskeleton of RBL-2H3 and P815 cells, before and after drug stimulation.…”

Biology of Naegleria spp.

“…The cytoskeletal structure of Naegleria amoeba has been examined by various investigators. Thick (17 to 19 nm) and thin (5 to 7 nm) microfilaments up to 256 nm in length, and morphologically similar to actin and myosin, have been seen in the cytoplasm of N. fjl1cri amoebae (125). Actin, the major polypeptide synthesized by N. gruiberi, has been purified to homogeneity (209).…”

“…Interaction between the microfilaments has been proposed as the mechanical means by which amoeboid locomotion is accomplished in Naegleria spp. (125,126). Amoeboid locomotion is perturbed by the addition of cytochalasin B (114).…”