ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS An ameba, bearing a fringe of scales on the plasmalemma surface, dwells among the filaments of the colonial, blue-green alga Trichodesmium thiebautii (Sournia), and preys upon bacteria growing within the colony. The cytoplasm is clearly differentiated into a fine fibrillar ectoplasm at the periphery of the cell and a central endoplasm containing most of the membranous organelles. The nucleus contains a spheroidal nucleolus which is centrally located, and a double membrane containing pores. The tubular mitochondria, microbodies, lysosomes, and endoplasmic reticulum are typical for protozoa. The Golgi apparatus consists of an array of elongate flattened cisternae. One surface is associated with a fine fibrillar layer and the opposite surface contains electron-dense vesicles (perhaps primary lysosomes) and scale-containing vesicles that appear to be the origin of the scales deposited on the plasma membrane. Three kinds of bacteria-containing vacuoles are presnt: (a) vacuoles surrounded by 3 membranes and containing bacteria that are either healthy or in an early stage of digestion, (b) singlemembrane vacuoles which are food vacuoles that become converted to digestive vacuoles, and (c) larger vacuoles resembling those in (b) which contain prey in an advanced stage of digestion. The presence of amebae within pelagic algal communities provides further evidence for the diversity of their habitats in the ocean.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1977.tb04753.x
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