Thinking about flagellar oscillation

Bending of cilia and flagella results from sliding between the microtubular outer doublets, driven by dynein motor enzymes. This review reminds us that many questions remain to be answered before we can understand how dynein-driven sliding causes the oscillatory bending of cilia and flagella. Does oscillation require switching between two distinct, persistent modes of dynein activity? Only one mode, an active forward mode, has been characterized, but an alternative mode, either inactive or reverse, appears to be required. Does switching between modes use information from curvature, sliding direction, or both? Is there a mechanism for reciprocal inhibition? Can a localized capability for oscillatory sliding become self-organized to produce the metachronal phase differences required for bend propagation? Are interactions between adjacent dyneins important for regulation of oscillation and bend propagation? Cell Motil. Cytoskeleton 2008. (c) 2008 Wiley-Liss, Inc.     

Thinking big about global health

The Gates Foundation is funding high-risk research into new ways to improve health in developing countries, but ensuring that the fruits of these studies reach the people who need them most may be the biggest challenge of all.     

Thinking about Death Reduces Delay Discounting

The current study tested competing predictions regarding the effect of mortality salience on delay discounting. One prediction, based on evolutionary considerations, was that reminders of death increase the value of the present. Another prediction, based in part on construal level theory, was that reminders of death increase the value of the future. One-hundred eighteen participants thought about personal mortality or a control topic and then completed an inter-temporal choice task pitting the chance to gain $50 now against increasingly attractive rewards three months later. Consistent with the hypothesis inspired by construal theory, participants in the mortality salience condition traded $50 now for $66.67 in three months, whereas participants in the dental pain salience condition required $72.84 in three months in lieu of $50 now. Thus, participants in the mortality salience condition discounted future monetary gains less than other participants, suggesting that thoughts of death may increase the subjective value of the future.     

现代生物技术引发的几点思考

现代生物技术正在改变着人类生活与思维方式,其发展有可能重新实现了人与自然的共存与进化,但也不可避免地产生生物战争、伦理道德、法律、社会、食品安全、工农业生产、能源、环境等一些新的问题,令人们深思。     

Transforming Our Thinking about Transitional Forms

A common misconception of evolutionary biology is that it involves a search for “missing links” in the history of life. Relying on this misconception, antievolutionists present the supposed absence of transitional forms from the fossil record as evidence against evolution. Students of biology need to understand that evolution is a branching process, paleontologists do not expect to find “missing links,” and evolutionary research uses independent lines of evidence to test hypotheses and make conclusions about the history of life. Teachers can facilitate such learning by incorporating cladistics and tree-thinking into the curriculum and using evograms to focus on important evolutionary transitions.     

Thinking about mind and matter from biology

In biology, man is an object of research; therefore the question might be asked whether inspirations can go from biological data to the reflections on the mind-matter relation in man. The social aspect of man, as treated by sociobiology, is left out of consideration. The knowledge that man is mind, or has a mind, is no result of biological research. It is a datum from philosophy. The biologist, however, is living in a culture which knows about the mental character of man, and this is incorporated in his investigations. He knows that mental activities are connected with processes in the central nervous system and that, especially in the brain, localizations of mental activities are found. As a result of the split-brain experiments with patients and animals, some have arrived at the conclusion that there is a double consciousness. An approach from biology can lead to statements of a philosophical character, as, for example, statements about the unity, or even identity, of mind and matter. The theories of identity meet with great interest in scientific circles, and the truth value of identity statements is investigated. The system theory is taken into consideration. On a philosophical level a revaluation of the concept of matter can lead to a different sort of identity theory.     

关于动物放生监管的思考

放生活动作为一种宗教习俗在我国有着悠久的历史和一定的群众基础。由于缺乏专业指导和监管,放生引起了环境污染、生态入侵等危害自然生态系统和生态安全的事件,造成大量放生动物无效死亡、危害公共安全、助长非法猎捕等,影响放生地居民正常的生产生活,给野生动物保护与管理带来隐患,同时也违背了放生"尊重生命"的本意。2016年新修订的《中华人民共和国野生动物保护法》将动物放生纳入管理范围,使对动物放生的监管有了明确的法律依据和支持,切合我国自然保护的现实需求。为实现对放生活动的科学监管,本文建议继续完善法规来加强放生管理,明确监管部门,制定放生管理的技术标准和管理制度,提出包括放生环境选址、放生动物规模、放生动物适合度、放生时间地点和放生监测方案等指标的放生技术标准,以期为放生提供制度和技术保障,使动物放生得以科学、有序、安全开展。同时,放生本质上仍然是人类对自然生态系统的干扰,科学放生的终极目标应为取消放生,建议通过更新观念、开展动物及栖息地保护来实现关爱动物的放生目的。     

Sociality Motivation and Anthropomorphic Thinking about Pets

Sociality motivation, the need to feel socially connected with others, has been proposed as an important determinant of individual variation in anthropomorphic thinking. Specifically, it has been suggested that people who are socially isolated or disconnected will tend to infer more human-like mental states in animals and other nonhuman agents (computers, robots, metaphysical beings, etc.), than those who have higher levels of contact with other people. We investigated this hypothesis in a community-based sample of cat and dog owners, measuring degree of anthropomorphism by asking them which emotions they believed their pet was capable of experiencing, how likely they were to rely on it for social support, and how attached they were to it. Structural measures of social disconnection, including the number of other adults living in the household and the number of social contacts outside the home, were not generally associated with the tendency to think anthropomorphically about pets. However, owners living in households with no children (under the age of 16 years) reported higher levels of attachment to their pet than did those with children (B = 1.678, p < 0.001), and felt that they derived relatively more social support from it than they did from humans (F_(1,244) = 4.997, p < 0.05, partial η² = 0.020). In addition, a trait-based indicator of social disconnection (self-reported anxiety about human social relationships) was associated with a heightened tendency for owners to report turning to their pet for support (F_(1,244) = 19.617, p < 0.001, partial η² = 0.074), and attributing more human-like emotions to it (F_(1,244) = 8.354, p < 0.005, partial η² = 0.033). These findings support a link between social disconnection and anthropomorphic thinking in a community setting; they also suggest that different forms of social disconnection (structural and trait-based) may generate different types of sociality motivation, and thereby influence different facets of anthropomorphic thinking.     

When We Stop Thinking about Microbes as Cells

Microbes are often thought of as individual cells. However, in their natural habitats, they typically exist in the context of other cells, be they of the same or different species. How these cells interact in space and time is key to their ecology and evolution. In this perspective, we consider the implications of this in terms of the future of microbiological research.This article is part of the special issue "Microbiology: how to bridge mechanisms and phenomenology" edited by Suckjoon Jun.     

Thinking about Bacillus subtilis as a multicellular organism

Initial attempts to use colony morphogenesis as a tool to investigate bacterial multicellularity were limited by the fact that laboratory strains often have lost many of their developmental properties. Recent advances in elucidating the molecular mechanisms underlying colony morphogenesis have been made possible through the use of undomesticated strains. In particular, Bacillus subtilis has proven to be a remarkable model system to study colony morphogenesis because of its well-characterized developmental features. Genetic screens that analyze mutants defective in colony morphology have led to the discovery of an intricate regulatory network that controls the production of an extracellular matrix. This matrix is essential for the development of complex colony architecture characterized by aerial projections that serve as preferential sites for sporulation. While much progress has been made, the challenge for future studies will be to determine the underlying mechanisms that regulate development such that differentiation occurs in a spatially and temporally organized manner.     

Modeling Historical Ecology, Thinking about Contemporary Systems

One way to make archaeological trajectories compelling to contemporary audiences is through detailed computer simulation with graphical interfaces that allow students or researchers to explore historical sequences and ask "what if" questions of them. We discuss progress on modeling coupled human systems and ecosystems over long periods in the Mesa Verde region of the U.S. Southwest, a project developed with both research and educational products in mind. The project has many foci, but here we concentrate on fuel-wood availability and its pre-Hispanic use in the pygmy forests of this region. Our preliminary results tend to indicate that wood for fuels became sufficiently limited in this sequence to become a factor of considerable importance in decisions about where to live, how to build, and even whether to remain in the region. The same logic of modeling can be used to study problems of contemporary forest use in other parts of the world.