PROGRESS IN PROTOZOOLOGY

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270 H. PLATTNER ET AL» Some time ago we have documenlted the occurrence of some ill defined, electron dense "connecting material" between trichocyst and cell membrane (Plattner et al. 1975, 1977). This material has now been further characterized by group- and charge-specific electron stains in conjunction with enzymatic extraction experiments (W e s t p h a 1 and Plattner 1981 a, b; see Fig 4); it represents protein(s) with a surplus of negative charges. Similar analyses with nd 9 cells grown under permissive or non-permissive conditions, revealed that the simultaneous presence (or absence) of "connecting material" (and of "rosettes"; see above) is correlated with the (un-) capability for exocytosis performance (Beisson et al. 1980, Matt et al. 1980, Plattner et al. 1980). We have chosen the term "connecting material" because of our ignorance on its precise nature and function (for possible speculations see below) and to indicate that it connects physically the trichocyst and cell membrane (selectively in those strains which are capable of membrane fusion: Plattner et al. 1980); this holds for a variety of exocytosis trigger procedures (Matt et al. 1980). Furthermore, microinjection studies using exocytotically normal and defective Paramecium tetraurelia strains as donors and/or receptors gave independent support for the functional importance of a kind of "connecting material" (Beisson et al. 1980). Table 1 summarizes some of the features relevant for exocvtotic membrane fusion in Paramecium tetraurelia. Not only the "connecting material" between trichocyst and cell membrane is sensitive selectively to proteolytic enzymes (W e s t p h a 1 and Plattner, 1981 a, b; Fig. 4) but also the "rosette" (and the "ring") MIP when analyzed by freeze-fracturing (V i 1 m a r t and P la 11 n e r 1983). In conclusion, the potential exocytotic fusion sites in paramecia contain both membrane-integrated and membrane-associated proteins. This is quite opposite to what was almost generally believed to be essential for membrane fusion in metazoan cells (for MIP c.f. Orci and Perrelet 1978; for membrane associated material c.f. Laws on and Raff 1979). Studies with model systems (liposomes) had also come to the conclusion of a primary role of membrane lipids for the determination of fusion capacity (c.f. Papahadjopoulos 1978). How can these discrepancies be reconciled? Some points were recently discussed within a broader frame (Plattner 1981) and ithe most crucial aspects pertinent to membrane fusions in protozoa will be discussed in more detail in the following. What might be the functional role of (this assembly of membraneintegrated and membrane-attached proteins for membrane fusion? With certain expectations in mind we localized a Ca 2 +-stimulated ATPase http://rcin.org.pl
Table 1 Characterization of exocytotic membrane fusion in Paramecium tetraurelia strains* Ciliary reversal upon triggering Matrix stretching in vitro (/3 •115 E w +' » a« .2 OQ Ô c/3 y, «.- X g > § « § » g a ^ Ultra thin sect Freeze-fra cture 2 + Ca ATPase "connecting material" "rings" "rosettes" Exocytosis capacity Trichocyst attachment to cell membrane Strain + + + + + 1 higher lower + 1 + 1 lower i 1 | 1 + 1 u + + * • + + 1 1 + 1 1 + + 1 7 S, K401 nd 9 (18°C) nd 6, nd 1 nd 9 (28°C) tarn 38, tl (trichless) http://rcin.org.pl I * Data pooled from B e i s s o n et al. (1976, 1980), B i 1 i n s k i et al. (1981), Lefort-Tran et al. (1980), Plattner et al. (1973 1975, 1977, 1980), Matt et al. (1980), Westphal and Plattner (in press) and Beisson et al. (unpublished results). ** In form of "parentheses".
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POLISH ACADEMY OF SCIENCES NENCKI I
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PROGRESS IN PROTOZOOLOGY Proceeding
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INTRODUCTORY REMARKS This Part II o
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PROGRESS IN PROTOZOOLOGY Proceeding
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183 In his abstract Mignot (1981) s
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PHYLOGENETIC RELATIONSHIPS AMONG PR
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187 algae by phycologists (Bourelly
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195 The foregoing subdivisions of A
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209 vine et al. 1980), there is no
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213 evidence for the assumption of
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REFERENCES 215 Bardele C. F. 1977:
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Page 51 and 52: 225 brate cycle in vitro. Further c
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Page 55 and 56: 229 for the development of methods
Page 57 and 58: IN VITRO CULTIVATION OF PARASITIC P
Page 59 and 60: Malaria IN VITRO CULTIVATION OF PAR
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Page 63 and 64: 237 Rai Choudhuri A. N.. Chowdhuri
Page 67 and 68: 241 Only those with 9-type 1 fronto
Page 71 and 72: THE MOLECULAR DIVERSITY OF TETRAHYM
Page 73 and 74: 247 in eukaryotes. It is about the
Page 75 and 76: Table 2 Mating species of Tetrahyme
Page 83 and 84: Table 8 Percentage of DNA reanneali
Page 85 and 86: 259 pattern; they do confirm our ju
Page 89 and 90: Table 13 Two-dimensional electropho
Page 91 and 92: 265 Cuny M., Milet M. and Hayes D.
Page 95: MEMBRANE FUSIONS IN PROTOZOA 269 It
Page 99 and 100: Fig. 3. Freeze fractured trichocyst
Page 101 and 102: * 1 ^MBBHBBHBBBBI jgf'- Fig. 5. Tan
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Page 105 and 106: MEMBRANE FUSIONS IN PROTOZOA 275 ba
Page 107 and 108: 277 B i 1 i n s k i M., Plattner H.
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Page 111 and 112: 281 structure and cytochemistry of
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Page 123 and 124: 293 Co-Chairman: Jan Kućera, Czech
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WARSAW 1981 http://rcin.org.pl
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CONTENTS Introductory Remarks 179 B
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