Ciliates of a group of closely related species of the genus Euplotes harbor Polynucleobacter bacteria, and apparently need them in order to successfully reproduce. In the present paper we investigate the possible metabolic correlation between the two partners in this symbiosis. We examine and compare behavioral, ultrastructural and cytochemical analysis specimens of E. harpa, with and without their symbionts. The results show that aposymbiotic cells do not undergo a sharp blockage of their cell cycle: they are able to start and go on with DNA replication and, in some cases, nuclear division; in a few cases they can even start cytoplasmic division. Electron microscopical observation reveals that these cells are no longer able to perform glycogenolysis. A similar deficiency was observed in aposymbiotic E. aediculatus. In all likelihood, this failure deprives them of an important energy source useful for the accomplishment of the energetically costly fission process. These results are in agreement with the assumption that the bacteria compensate for their hosts’ metabolic disorder and prove that this disorder concerns glycogen metabolism. The fact that Polynucleobacter-like bacteria are present in every organism of several different, closely correlated, Euplotes species and are vertically transmitted from generation to generation, indicates that we are dealing with a hereditary disorder, possibly an enzymatic deficiency, as happens in the human genetic diseases referred to as glycogenosis, and that the bacteria make up for this deficiency.
|Autori:||VANNINI C; LUCCHESI S; ROSATI G|
|Titolo:||Polynucleobacter: Symbiotic bacteria in ciliates compensate for a genetic disorder in glycogenolysis|
|Anno del prodotto:||2007|
|Appare nelle tipologie:||1.1 Articolo in rivista|