In optogenetics, not only channelrhodopsins but also animal opsins have been used as efficient optical control tools. Animal opsins have been extensively investigated using various spectroscopic, biochemical, electrophysiological, and biophysical research techniques for more than 150 years. Based on the accumulated insights, I introduce functional characteristics of animal opsins, and discuss their potentials as optical control tools to expand our understanding of biological phenomena. In particular, I summarize advantages of “invertebrate-type” opsins as optical control tools, because they can function without supply of “cis-” retinal isomers and they can be activated and inactivated by stimulation of different color of light.
Since protists are single-celled organisms, one might think that these organisms live a solitary life, independent of other organisms. In reality, however, many protists develop complex interrelationships with other unicellular and multicellular organisms. For example, predatory protists recognize and capture other organisms as prey. On the other hand, to escape from predators, they need to recognize their enemies correctly. Some protists recognize cells of the same species of different cell types for sexual reproduction. Some are symbiotic with other eukaryotes or prokaryotes in their cells, and some are symbiotic in the bodies of other larger organisms. There are also protozoa that can infect animals and cause disease. Recent studies have revealed the mechanisms by which protists recognize other organisms. As a result, we have gained many unique insights into the molecular mechanisms of cellular interactions between protists and other organisms, and the aspects of biological evolution driven by these interactions. This review provides an overview of the latest research findings on cell-cell interactions in protist prey recognition, with a particular focus on their molecular and evolutionary perspectives.
Eusocial hymenopteran insects including bees and ants consist of a kin group centered on a queen, which are known as colony. Their society, which is based on kin, is extremely advanced, and high productivity is achieved by not only the division of labor such as foraging and brood care, but also role of reproduction between individuals. The evolution of society and mechanism backgrounds maintaining it are closely related to their mating system, which influences their kinship within colony that promote the incentive for cooperation between individuals, and likelihood of inbreeding in relation to the colonies’survivorship. Honeybee (Apis mellifera) is well known as eusocial insects, and numerous knowledges for their mating have accumulated. This article reviews the mating behavior and system of honeybees, and also some problems on reproduction and the functionality for avoiding them.