Infectious particles in a marine ciliate

Abstract

INFECTIOUS, self-reproducing particles of unknown origin have been demonstrated in various tissues and cells^1,2, notably fresh water protozoa³, but not in marine protozoa. Advances in the development of culture media for marine ciliates⁴ and the need for simple model systems for biochemical study of intracytoplasmic particles have led us to survey marine protozoa. Of 104 isolates made from twenty-one seawater samples taken from tidal pools and brackish backwaters along the South Florida coast, twenty-six were cultivated axenically as described before⁴. Of these, four contained in their cytoplasm infectious, self-reproducing particles, which we have termed ‘xenosomes’ (xenos, alien; soma, body).