The ciliate Euplotidium itoi and its episymbionts (epixenosomes) influence each other
Rosati,G. and Verni, F.
Dipartimento Etologia, Ecologia, Evoluzione, Via A. Volta 4, I-56126 Pisa, Italy
The hypotrich ciliate Euplotidium itoi harbors, on its dorsal surface, enigmatic episymbiotic organisms referred to as epixenosomes. This association is constant in nature and the cell cycles of the two organisms are well coordinated. It appears not only that the host cell strong influences the epixenosomes but also that the epixenosomes themselves influence the ciliate at least to a certain extent. This implies that the two organisms in some way "communicate". By means of different technical procedures at the electron microscopical level, membrane-bound vesicles (70-100 nm in diameter) have often been observed as emerging from (or fusing with) the cell membrane of the epixenosomes and the cell membrane of Euplotidium in the region where the symbionts are lodged. Similar vesicles have been found inside the ciliate cytoplasm, just under the cortex while specialized sites on the epixenosomal surface (recalling those considered as "pinocytotic sites" in other organisms) have been revealed by freeze etching preparation. The involvement of these structures may be hypothesized as a direct passage of material between epixenosomes and Euplotidium. Considering that epixenosomes live externally to their host and that a contact between the membranes of the two organisms has never been observed these vesicles could represent an unusual "communication" way.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Wednesday, April 8 |
10:40 am |