AbstractSteroids are ubiquitous in natural environments and are a significant growth substrate for microorganisms. Steroid degradation is therefore relevant to global biogeochemistry. Microbial steroid metabolism is also important for some pathogens and for biotechnical applications. Moreover, the presence of steroid hormones in the environment has become a major issue in environmental science and policy because these compounds (e.g. estrogens at sub-ng/L concentrations) interfere with the endocrine system and alter diverse physiological functions including reproduction and development in animals, especially aquatic species. Biodegradation has been considered a crucial process for removing steroid hormones from the contaminated ecosystems. Thus far, numerous steroid degraders have been isolated and characterized. However, biochemical mechanisms underlying microbial steroid metabolism are largely unknown. Furthermore, literature on the ecophysiological relevance of steroid-degrading organisms in the environment is extremely limited. In the past decade, we have proposed several aerobic and anaerobic steroid degradation pathways in model organisms. We also studied the distribution of these degradation pathways in diverse environments. The current results show that steroid-degrading bacteria are globally distributed and prevalent in particular environments, such as wastewater treatment plants, soil, plant rhizospheres, and the marine environment, including marine sponges.
AbstractMountain lakes are natural and remoted lentic water bodies with unique ecosystem structure housing high level of biological endemism. Yet, only limited investigation has been undertaken in such ecologically important habitats in tropical/subtropical Asia. As the subtropical mountain lake ecosystems are strongly influenced by seasonal environmental perturbations, including periodic and stochastic hydrological disturbances due to heavy rainfall events, and the intense solar radiation during summer. This could be the major factor characterizing the energy basis for the lake food webs. In addition, mountain lakes are naturally fishless due to their oligotrophic status. Artificial introduction of fish into mountain lakes has been however commonly seen worldwide, this could result in effective modification of food web and trophic status of the lake ecosystems. Since most mountain lakes have been influenced by regional and globally climatic and environmental changes, it would be essential to enhance our ecological knowledge in the prestigious mountain lakes and determine the major factors causing the changes of ecosystem structure and functions therein. In this study, the trophic structure and food utilization patterns of different fish consumers in two subtropical mountain lakes in Taiwan, including Lake Tsuifeng and Lake Yuanyang were investigated using stable carbon and nitrogen isotope analyses in association with gut content analysis. Despite the high similarity in climatic influence, the two study lakes exhibited marked environmental differences. This resulted in distinct difference in the availability of different food sources to the food webs. Our findings indicated that allochthonous food sources, i.e. fine particulate organic matter and leaf litter were least utilized by most fish consumers despite their high availability. In contrast, fish consumers showed strong dependence on relatively rare autochthonous food sources (periphyton and phytoplankton) which represented the major primary production supporting the food web. Results could be further discussed.
AbstractHow good is our chance of surviving global warming and geopolitical disasters? To make good predictions that may boost our wellbeing, we should not only acquire knowledge and expertise in various fields, but also reflect on our attitude of coping with problems and issues in real life. Actually, Tetlock and Gardner in their co-authored book Superforecasting (2015) argue that non-experts may have a greater chance of making correct predictions than experts who have been working on specific areas of knowledge. They discover through their experiments and interviews that perceptive generalists or laypeople have the strong motive of absorbing wide-ranging information, and they are quite ready to revise their assumptions in relation to others’ feedback or actual happenings around the world. How may such intriguing discovery change our temperaments and styles of serving global academic communities? Following Tetlock and Gardner’s work, the speaker takes a further step to push for the urgency of cultivating foresight when it comes to our observation and appreciation of all life forms in nature and culture. In the world of eco-biology, predictability is also one of the key measures in mapping and manipulating the interactions between living beings found in diverse environments. In this presentation, the speaker illustrates how we can draw on our precious foresight to achieve stunning cooperation with life forms that certain experts may still find daunting and nerve-wracking. It is argued that our empathetic attitude governs not only our prospects of endearing diverse life forms, but also our strength of making correct predictions while dealing with thorny problems in real life.