Yeasts are extensively used in molecular genetics as model eukaryotic organisms, and thus are sometimes called “eukaryotic E. coli”. Unfortunately only a small number of attempts have been made at adapting yeasts as a teaching material of genetics in high school. I report here the results of molecular genetic experiments using a yeast as a material, which may be utilized in practical education in high school. Major results are summarized as follows :

1. A wild-type strain of yeast having functional mitochondria (ρ⁺) was treated with ethidium bromide to isolate mutants that have functionally abberrant mitochondria (ρ^–). Optimal concentration of ethidium bromide was about 50 µg/ml per 10⁶ cells/ml.

2. The activity of succinate dehydrogenase was used as a markar of mitochondrial function. The two types of cells were found to be clearly different in the enzymatic activity in the logarithmic growth phase.

3. These experiments were introduced into the class as student experiments. All of the experiments planned were successful. The reports of students and the results of preexperiment test and post-experiment test indicated that the students understood clearly the meaning of the experiments. Most of the students (total number was 43) expressed positive impressions to this practice of experiments.

A scientific specimen of macro algae is made generally in a dried or a liquid immersed form. However, these specimens are not satisfactory for the conservation of three dimensional structure and color of algal thalli. In this study, we attempted to make a 3-dimensional specimen embedded in polyester resin for a useful teaching material in biology education. This 3-dimensional specimen has high resistance to environmental light and oxygen. It keeps the structure and color of algal thalli for a long time.

For macro Chlorophyta, the members of Ulvales having a membranous thallus were successfully dried with far infrared radiation and embedded in the resin. However, in the case of coenocytic algae such as Codium or Valonia, algal thalli were extremely shrank and could not be used as a specimen. For Phaeophyta, though algae with thick or tough thallus were successfully dried, their color had changed when embedded in the resin. In the case of Fucales algae, their floating bladders were shrank and also discolored. For Rhodophyta, algae with tough thallus such as the members of Corallinaceae or Cryptonemiaceae, were easily made into the resin embedded 3-dimensional specimen.

Introducing 3-dimensional algal specimen as a teaching material into a biology education curriculum, the learner’s concept of plants should be extended.

Population of Paramecium bursaria cells exhibits a circadian rhythm of photoaccumulation. The mean period of the rhythm is about 25.3 hours in LL at 25°C. In this experiment, the photoaccumulation rhythms of some strains of P. bursaria are measured automatically by using the microcomputer. The period of photoaccumulation rhythm in the strain of BG is about 22.2 hours, which is shorter than the mean level. The period of T316 is about 27.4 hours, which is longer than the mean level. The correlation between the period of mating reactivity rhythm of this strain, which was about 27.0 hours, is almost similar to that of photoaccumulation rhythm in the strain of T316, This result shows the possibility that there is an endgeneous circadian oscillator which controls both of two rhythms photoaccumulation and mating reactivity.