Characterization of the blue protein in the shell pattern of Japanese littleneck clam (Ruditapes philippinarum ) was performed by purification using anion-exchange chromatography, amino acid analysis, molecular weight measurements, quantification of ferric ions, etc. Blue colored two components were found by anion exchange chromatography. The blue colored shell protein and the colorless mantle protein were found to be homologous to each other in amino acid composition; they are acidic proteins rich in aspartic acid and glutamic acid and that the isoelectric point of the blue protein was estimated as pI =3.96. The secondary structures of the blue protein were estimated as α-helix (28.6%), β-sheet (20.1%), and random coil (51.3%). From combination of molecular weight measurements and quantification of ferric ions, it was found that the blue protein is formed as trimer or tetramer from the monomer proteins of about 10 kDa by complexing with ferric ion. It was also found that there are two kinds of ferric ion existing states and that reducing agents decompose the blue colored trimer or tetramer into dimer or smaller units accompanying decolorization.

Microscopic observation is one of the most basic and important skills for experiments in biology classes from compulsory education through to higher education. Microscopic observation in biology can help us better understand the microstructures of organisms and convey notions of beauty and fascination regarding the detailed nature of the microworld, which we cannot observe through our unaided eyes. However, many lab classes were postponed for the summer break because it was difficult for the faculty to conduct lab classes using equipment such as microscopes for non-face-toface learning at the university in the beginning of the COVID-19 pandemic. Under this situation, we planned that students do the experiment at home using handmade microscope. Students could make a simple Leeuwenhoek microscope very easily and use to understand the principle of the microscope. A non-face-to-face class required students to take the initiative in learning, which led to a better understanding of the principles of microscopy. Hence, the future integration of this nonface-to-face learning using a handmade microscope into an existing face-to-face lab class will be very useful for the teaching of science, especially biology, at many schools by science teachers and researchers.

A tide –generating force has two dynamic properties. One of them is a property as a vector with magnitude and direction, the other is a periodicity of force acting with a cycle of about 12 hours. If the tide-generating force is a periodic external force, the tides must be a kind of forced oscillation phenomena. Three proposals regarding the origin of tides will be suggested in this article. (1) The ocean tides can be divided into three types by the depth. They are ‘out of phase’ type (shallower than 22,000m), ‘in phase’ type (deeper than 22,000m) and ‘resonance’ type (equal to 22,000m). The actual ocean tides are classified into the ‘out of phase’ type. On the other hand, the Earth tides occurring on the solid Earth are classified into the ‘in phase’ type. (2) Dynamic movement pictures of each type of tides have been determined. Unlike the widely accepted explanation, the global form of the ocean surface repeats an oval and a circle in turn according to the Moon’s position. As a result, the tidal movements of the ocean will occur in fixed four areas with an angular distance of 90 degrees apart along the equator, and four spots escaping any tidal movements will appear between them. (3) A new concept of ‘tide burst’ is deduced and its scientific meanings are discussed. Judging from the delay of Earth’s rotation period, the tide burst will happen in the ocean about 4.5 billion years from the present.