Characterization of sulfur-compound metabolism underlying wax-ester fermentation in Euglena gracilis

Euglena gracilis is a microalga, which has been used as a model organism for decades. Recent technological advances have enabled mass cultivation of this species for industrial applications such as feedstock in nutritional foods and cosmetics. E. gracilis degrades its storage polysaccharide (paramylon) under hypoxic conditions for energy acquisition by an oxygen-independent process and accumulates high amount of wax-ester as a by-product. Using this sequence of reactions referred to as wax-ester fermentation, E. gracilis is studied for its application in biofuel production. Although the wax-ester production pathway is well characterized, little is known regarding the biochemical reactions underlying the main metabolic route, especially, the existence of an unknown sulfur-compound metabolism implied by the nasty odor generation accompanying the wax-ester fermentation. In this study, we show sulfur-metabolomics of E. gracilis in aerobic and hypoxic conditions, to reveal the biochemical reactions that occur during wax-ester synthesis. Our results helped us in identifying hydrogen sulfide (H2S) as the nasty odor-producing component in wax-ester fermentation. In addition, the results indicate that glutathione and protein degrades during hypoxia, whereas cysteine, methionine, and their metabolites increase in the cells. This indicates that this shift of abundance in sulfur compounds is the cause of H2S synthesis

Distribution and Ecology of Birds of Japan

The effects of island biogeography are clearly seen in the avifauna of Japan. Species composition and distribution reflect Japan's geographic, climatic, vegetational, topographical, and geological characteristics. It is a country composed primarily of mountainous, forested islands that lies off the coast of a continent rich in bird life. Though Japan has a wide range of climates and diverse forest habitats, the terrestrial and freshwater avifauna is depauperate when compared with species, family, and order diversity on the nearby continent, which is both larger in total area and more diverse in habitats. However, the bird groups that do have higher species diversity in Japan than in the Asian mainland are seabirds. The large, productive ocean area and small, isolated islands provide them with foraging and nesting sites, and the long geographic range of Japan allows seabirds from both northern and southern regions to nest in the Islands. Island biogeography also affects the ecology of many terrestrial species. Niche shift and expansion of foraging and parasitic behaviors are seen in populations established on islands where the species composition does not include certain competitors. The terrestrial species resident on small islands have developed unique breeding behavior, in comparison with their conspecifics on larger islands, such as smaller clutch size, exaggerated begging behavior, and longer parental care in small-island populations of Varied Tits, Parus varius Temminck & Schlegel