Photic Responses and Sensory Transduction in Motile Protists. In: Autrum H, editor. Comparative Physiology and Evolution of Vision in Invertebrates. Berlin: Springer Berlin Heidelberg; 1979. pp. 23-68. [DOI: 10.1007/978-3-642-66999-6_2]

Photoperception and photomovement

The photoperception systems in photomovement show a great diversity at several levels, (i) Different types of photomovement (namely photokinesis, photophobic response, phototaxis) make use of completely different perception systems even in the same organism, (ii) In different organisms a given type of photomovement is mediated by different and unrelated systems, as is shown in this paper particularly for phototaxis, (iii) In certain cases, a single response in one organism can be controlled by two separate and independent photoperception systems, which may even be located in different compartments. This diversity sets photomovement apart from photosynthesis and vision, which are highly uniform and stable in evolution. Possible consequences for considering the evolution are discussed.

Microcomputerized measurement of the circadian locomotor rhythm in microorganisms

A computerized close-up video/photoamplifier system was implemented for the study of circadian locomotor rhythm in a population of a ciliate protozoan, Paramecium. This fully microcomputerized system facilitated automatic long-term measurement of three parameters in parallel: (1) numbers of specimens per 10 min traversing beneath a fixed point in an experimental vessel, (2) times taken by specimens to traverse the point, and (3) interval times between subsequent specimens traversing the point. Stochastic analyses using these parameters can derive the circadian fluctuation of physiological variables, such as swimming speed and the frequency of avoiding reaction (abrupt change in swimming direction). The computerized system simultaneously accomplished the acquisition of these three sets of data, their transient storage, and their graphic display according to given format. The system software was constituted so that an experimenter with little computer knowledge, could easily operate the system by answering questions displayed on the computer monitor.