Production and characterization of three polyclonal antibodies raised against cyst wall proteins of a hypotrichous ciliate

Three polyclonal antibodies raised against Paraurostyla sp. cyst wall polypeptides of molecular weight 110,000 (p110), 66,000 (p66) and 52,000 (p52) have been obtained. The specificity of the antisera was tested by immunoblotting. Anti-p110 antibody detected five bands of 300, 170, 135, 110 and 40 kDa, respectively. Antiserum obtained against p66 recognized only this protein. Anti-p52 antiserum showed reaction for two different bands of 52 and 44 kDa, respectively. The precise localization of these proteins in the cyst wall was assessed by light microscope immunocytochemistry. Anti-p110 antiserum produced a strong positive reaction in both the ectocyst and endocyst. Both anti-p66 and anti-p52 antibodies recognized the ectocyst.

Reversibility of encystment in the ciliate, Histriculus cavicola (kahl, 1935) (ciliophora: stichotrichia)

An early phase of encystment of the ciliate, Histriculus cavicola is subdivided into 5 stages, stages A to E. Resorption of feeding organelles, undulating membranes (UM) and the adorai zone of membranelles (AZM) start from stage B. In stage E cells, resorption of UM is completed and that of the AZM reaches to the level of anterior end of left marginal cirral row from its posterior end. When stage A cells are transferred in culture medium with or without food organisms, or in normal or 10 times concentrated Osterhout's solutions with food, most cells do not encyst. More than half of stage C cells do not encyst at 20°C after transfer in culture medium. All stage E cells encyst, irrespective of the medium or of the presence or -the absence of food into which they are transferred. About half of stage A cells and all stage B to E cells contain ectocyst precursors. Our results indicate that initiation of ectocyst precursor formation does not necessarily direct the cells to encyst but cells in stage E are determined to encyst.

Towards a generalized model of encystment (cryptobiosis) in ciliates: a review and a hypothesis

In this work we propose a generalized model to explain encystment (cryptobiosis) in ciliates. The model is elaborated from both structural and physiological studies previously reported, and some hypothetical considerations. The main features of this model are the following: (a) starvation is considered as the most important inducer of ciliate encystment, and it constitutes the first trigger of this cell differentiation process; (b) the "switch on" of encystment genes involves the appearance of several new transcripts; (c) starvation involves cell autophagy and protein turnover, which provides material to synthesize the new cystic proteins; (d) cytoplasmic dehydration has an important role during the resting cyst formation; (e) a gradual loss of intracellular water can inactivate cell metabolism, leading to an ametabolic state (cryptobiosis); (f) as a late precystic event, the encysting cell forms a barrier (cyst wall), that isolates the cell from the hostile environment.