Ref ID : 3677
Takahashi Tadao; Reorganization in Amicronuleates with Defective Mouth of the Ciliate Pseudourostyla levis. J.Protozool. 35(1):142-150, 1988
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The purpose of this work is to examine the reorganization process in amicronuleates with defective mouth of the multimicronuclear ciliate, Pseudourostyla levis. The amicronulceates were derived from fragments obtained by transection of normal micronucleates. The cell size of the amicronuleates was extremely unstable and varied from 57.5 to 276.3 µm long (n=146), whereas the micronucleates kept rather stable cell lengths with a range from 162.5 to 266.3 µm (mean+/-SD=213.1+/-19.6 µm, n=206). The renucleates obtained by transplantation of a micronucleus to an amicronuleate returned to almost normal cell size (mean+/-SD=203.7+/-16.5 µm long, n=54). Under the usual culture conditions in the amicronucleate cell line, the number of abnormal cells with defective mouth rapidly increased, up to about 60%, until a stationary phase. Similarly, abnormal cells also appeared in micronuleates although the frequency was always less than 10%. The mean number of membranelles in the normal adoral zone of membranelles (AZM) was 82.6+/-3.9 (+/-SD, n=49) vs. 57.3+/-7.9 (n=81) in ciliates with defective mouths. The missing part of the AZM was always the anterior part of the lapel. Cells with defective mouth underwent reorganization (= physiological regeneration) under the usual culture conditions. During reorganization, the lapel part of the old AZM was transformed into a new collar part. The defective mouth was repaired through this developmental process. These results suggest that in P. levis the decrease of food supply often leads to the loss of a specific part of the AZM and that this membranellar loss is suppressed by the existence of micronuclei.