Research Interest

This laboratory focuses on (1) seasonal adaptation in invertebrates, and (2) circadian rhythms in animal society. We approach these studies from a perspective of comparative physiology and always consider the animals’ wild life and diversity in the course of our studies. Thus, our interests are firmly in sync with those of ecologists.

(1) Seasonal adaptation in invertebrates
    Seasons come around once a year and include the hot summer, cold winter, and also, rainy season, dry season. The biotic environment also changes considerably in accordance with these abiotic environmental changes. Since these changes are profound, almost all invertebrates adapt their life cycles to these seasonal changes to survive and reproduce. We are trying to elucidate the complete picture of seasonal adaptation at various levels of analyses: individual, cellular, and molecular.

Two different research projects are in progress in our laboratory. The first involves physiological analysis of life cycles; we are investigating physiological responses to environmental factors like temperature, daylength, or food that underly an animal’s actual life cycle. The current models used are primarily insects such as flies (Diptera) and stink bugs (Heteroptera), but we are expanding our field to cover the tadpole shrimp (Crustacea), the two-spotted spider mite (Arachnida), and the terrestrial slug (Mollusca).

The second project is aimed to elucidate the neuronal and molecular mechanisms of “photoperiodism” that play a critical role in the seasonal adaptations of terrestrial animals. Photoperiodism is the physiological reaction of organisms to daylength. We are now trying to clarify the underlying mechanisms by analyzing photoreceptor(s) and endocrine effector systems as well as the expression of circadian clock genes, mostly in flies.

(2) Circadian rhythms in animal society
   A large variety of organisms show circadian rhythms. The forms of circadian rhythms vary among species and also among life-stages within a species. For example, some social insect species are active throughout the day when they take care of the brood, whereas they show rhythm when foraging; some migrating birds fly throughout the day during migration, whereas they are rhythmic during the non-migration season. We focus on adaptations of the circadian rhythm in social insects. We mainly use bees as a model system to understand the regulation of circadian systems in the insect society. Recently, we have been interested in the mechanism underlying the behavioral arrhythmicity in bees inside nests and in the resetting (entrainment) of the circadian clock by social interactions in a bee colony.