PROGRESS IN PROTOZOOLOGY

PROGRESS IN PROTOZOOLOGY
Proceedings of VI International Congress of Protozoology
Special Congress Volume of ACTA PROTOZOOLOGICA
part II, pp. 267-278, 1984
Membrane Fusions in Protozoa.
A Survey Lecture with Special Emphasis on
Exocytosis in Ciliates
Helmut PLATTNER, Christel WESTPHAL,
Rolf TIGGEMANN and Heinrich MATT
Symposium C
Faculty of Biology, University of Konstanz, P.O.B. 5560, D-7750 Konstanz, FRG
General Remarks
As in metazoan cells, membrane fusion events are involved in a variety
of processes also in protist cells (see Fig. 1, see also Allen 1978 a).
Among them one can list the discharge (exocytosis) or uptake (endocytosis)
of molecules or bulk materials (pino- and phagocytosis), the
insertion and recycling of membrane components, fusion and fission processes
between certain intracellular compartments (e.g., lysosomes and
phagosomes etc.), certain osmoregulatory functions and the fusion of
cells (mating reactions). Some protozoa have at their disposition a highly
efficient and sophisticated "machinery" for membrane fusion-fission processes.
Such structures may be permanently "installed" either at operationally
favourable and, eventually in high redundancy, at precisely
predictable sites. This is in conitrast to most (not all) metazoan cells and
should facilitate correlated structural and functional analyses. This is
also the main reason why ciliated protozoa, notably Tetrahymena and
Paramecium, became important model systems for the situdy of membrane
fision events, particularly for the study of exocytosis; another
reason is the unique occurrence of exocytotic mutations in paramecia.
Paper presented at Symposium C on July 9 at VI International Congress of
Protozoology, Warsaw, Poland, 5-11 July, 1981.
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