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Zoological Science



Zoological Science 9(3):529-532. June 1992
10.34425/zs000984


Step-Up and Step-Down Photoresponses In Blepharisma

Matsuoka Tatsuomi, Taneda Koji

Department of Biology, Faculty of Science, Kochi University, Kochi 780, Japan


The cells of Blepharisma responded to a step-up in light intensity (step-up response) by ciliary reversal, while the cells showed a temporal repression of ciliary reversal which was accompanied by swimming acceleration when light intensity was suddenly decreased (step-down response). The step-up response occurred only in anterior fragments obtained by bisection of the cells, while the step-down response occurred in both of fragments. The topographical difference in photosensitivity indicates that the photoreceptor systems responsible for the step-up photophobic response might be different from those for the step-down photoresponse (repression of ciliary reversal accompanied by acceleration of swimming velocity).

Received: October 21, 1991 ;   Acccepted: March 2, 1992

Keywords: 


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