“If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made,” Allan Rechtschaffen said. Studies of sleep and sleep deprivation suggest that the functions of sleep include recovery at the cellular, network, and endocrine system levels, energy conservation and ecological adaptations, and a role in learning and synaptic plasticity.
A long-standing general principle in vision research holds that single photoreceptors always contain a single type of rhodopsin, although occasional examples of co-expressed rhodopsins, as the authors have now demonstrated for Drosophila, have cropped up in both vertebrates and invertebrates.
Food webs, which depict the networks of feeding interactions among co-occurring species, display many regularities in their structure. For example, the distributions of links to prey and links from predators, the percentages of omnivores and herbivores, and the mean trophic level of species change systematically with the number of taxa and feeding links in a web. Such “scale-dependent” regularities are formalized by network models based on a few simple link distribution rules that successfully predict the network structure of complex food webs from a variety of habitats. To explore how long such regularities may have persisted, we compiled and analyzed detailed food-web data for two ancient fossil assemblages from the early Paleozoic, when rapid diversification of multicellular species, body plans, and trophic roles occurred. Our analyses show that for most aspects of network structure, the Early Cambrian Chengjiang Shale and Middle Cambrian Burgess Shale food webs are very similar to modern webs. This suggests that there are strong and enduring constraints on the organization of feeding interactions in ecosystems. However, a few differences, particularly in the Chengjiang Shale web, suggest that some aspects of network structure were still in flux during early phases of de novo ecosystem construction.
PLoS Medicine aims to publish important studies from all medical disciplines that provide a substantial advance either in clinical practice, public heath policy, or basic pathophysiology. Though this is a lofty aim it is possible to see the journal’s role as primarily a passive one; presubmission inquiries and research articles arrive unsolicited, by which time evaluation by editors and reviewers for rigor, originality, and importance can do little to improve deficiencies in study methodology (largely a fait accompli by that point). However, we would argue that medical journals such as PLoS Medicine should seek to go beyond merely reflecting current trends in medical practice and research, by actively working to establish and promote standards that aim to improve the quality of research that is done.
In a new systematic review published in this issue of PLoS Medicine, Ian Sinha and colleagues examined studies that involved the selection of outcomes for use in paediatric clinical trials . As they say in their report, the choice of outcome is important because choosing inappropriate outcomes may lead to “wasted resources or misleading information which either overestimates, underestimates or completely misses the potential benefits of an intervention.”