Lots of new articles in four of seven PLoS journals. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Mendeley, Connotea, Stumbleupon, Facebook and Digg) with just one click. Here are my own picks for the week - you go and look for your own favourites:
As the oceans simultaneously warm, acidify and increase in PCO2, prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming. We examined the interactive effects of near-future ocean warming and increased acidification/PCO2 on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/PCO2 treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/PCO2 and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3°C) stimulated growth, producing significantly bigger larvae across all pH/PCO2 treatments up to a thermal threshold (+6°C). Increased acidity (-0.3-0.5 pH units) and hypercapnia significantly reduced larval calcification. A +3°C warming diminished the negative effects of acidification and hypercapnia on larval growth. This study of the effects of ocean warming and CO2 driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization) shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high PCO2 ocean would likely impair their performance with negative consequent effects for benthic adult populations.
Response of the Arctic Pteropod Limacina helicina to Projected Future Environmental Conditions:
Thecosome pteropods (pelagic mollusks) can play a key role in the food web of various marine ecosystems. They are a food source for zooplankton or higher predators such as fishes, whales and birds that is particularly important in high latitude areas. Since they harbor a highly soluble aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The effect of changes in the seawater chemistry was investigated on Limacina helicina, a key species of Arctic pelagic ecosystems. Individuals were kept in the laboratory under controlled pCO2 levels of 280, 380, 550, 760 and 1020 µatm and at control (0°C) and elevated (4°C) temperatures. The respiration rate was unaffected by pCO2 at control temperature, but significantly increased as a function of the pCO2 level at elevated temperature. pCO2 had no effect on the gut clearance rate at either temperature. Precipitation of CaCO3, measured as the incorporation of 45Ca, significantly declined as a function of pCO2 at both temperatures. The decrease in calcium carbonate precipitation was highly correlated to the aragonite saturation state. Even though this study demonstrates that pteropods are able to precipitate calcium carbonate at low aragonite saturation state, the results support the current concern for the future of Arctic pteropods, as the production of their shell appears to be very sensitive to decreased pH. A decline of pteropod populations would likely cause dramatic changes to various pelagic ecosystems.
Nonadaptive Fluctuation in an Adaptive Sensory System: Bacterial Chemoreceptor:
Sensory systems often exhibit an adaptation or desensitization after a transient response, making the system ready to receive a new signal over a wide range of backgrounds. Because of the strong influence of thermal stochastic fluctuations on the biomolecules responsible for the adaptation, such as many membrane receptors and channels, their response is inherently noisy, and the adaptive property is achieved as a statistical average. Here, we study a simple kinetic model characterizing the essential aspects of these adaptive molecular systems and show theoretically that, while such an adaptive sensory system exhibits a perfect adaptation property on average, its temporal stochastic fluctuations are able to be sensitive to the environmental conditions. Among the adaptive sensory systems, an extensively studied model system is the bacterial receptor responsible for chemotaxis. The model exhibits a nonadaptive fluctuation sensitive to the environmental ligand concentration, while perfect adaptation is achieved on average. Furthermore, we found that such nonadaptive fluctuation makes the bacterial behavior dependent on the environmental chemoattractant concentrations, which enhances the chemotactic performance. This result indicates that adaptive sensory systems can make use of such stochastic fluctuation to carry environmental information, which is not possible by means of the average, while keeping responsive to the changing stimulus.
The History of Makassan Trepang Fishing and Trade:
The Malayan term trepang describes a variety of edible holothurians commonly known as sea cucumbers. Although found in temperate and tropical marine waters all over the world, the centre of species diversity and abundance are the shallow coastal waters of Island Southeast Asia. For at least 300 years, trepang has been a highly priced commodity in the Chinese market. Originally, its fishing and trade was a specialized business, centred on the town of Makassar in South Sulawesi (Indonesia). The rise of trepang fishing in the 17th century added valuable export merchandize to the rich shallow seas surrounding the islands of Southeast Asia. This enabled local communities to become part of large trading networks and greatly supported their economic development. In this article, we follow Makassan trepang fishing and trading from its beginning until the industrialization of the fishery and worldwide depletion of sea cucumbers in the 20th century. Thereby, we identify a number of characteristics which trepang fishing shares with the exploitation of other marine resources, including (1) a strong influence of international markets, (2) the role of patron-client relationships which heavily influence the resource selection, and (3) the roving-bandit-syndrome, where fishermen exploit local stocks of valuable resources until they are depleted, and then move to another area. We suggest that understanding the similarities and differences between historical and recent exploitation of marine resources is an important step towards effective management solutions.
Toward a Mouse Neuroethology in the Laboratory Environment:
In this report we demonstrate that differences in cage type brought unexpected effects on aggressive behavior and neuroanatomical features of the mouse olfactory bulb. A careful characterization of two cage types, including a comparison of the auditory and temperature environments, coupled with a demonstration that naris occlusion abolishes the neuroanatomical changes, lead us to conclude that a likely important factor mediating the phenotypic changes we find is the olfactory environment of the two cages. We infer that seemingly innocuous changes in cage environment can affect sensory input relevant to mice and elicit profound effects on neural output. Study of the neural mechanisms underlying animal behavior in the laboratory environment should be broadened to include neuroethological approaches to examine how the laboratory environment (beyond animal well-being and enrichment) influences neural systems and behavior.
In many songbirds the larger vocal repertoire of males is associated with sexual dimorphism of the vocal control centers and muscles of the vocal organ, the syrinx. However, it is largely unknown how these differences are translated into different acoustic behavior. Here we show that the sound generating structures of the syrinx, the labia and the associated cartilaginous framework, also display sexual dimorphism. One of the bronchial half rings that position and tense the labia is larger in males, and the size and shape of the labia differ between males and females. The functional consequences of these differences were explored by denervating syringeal muscles. After denervation, both sexes produced equally low fundamental frequencies, but the driving pressure generally increased and was higher in males. Denervation strongly affected the relationship between driving pressure and fundamental frequency. The syringeal modifications in the male syrinx, in concert with dimorphisms in neural control and muscle mass, are most likely the foundation for the potential to generate an enhanced frequency range. Sexually dimorphic vocal behavior therefore arises from finely tuned modifications at every level of the motor cascade. This sexual dimorphism in frequency control illustrates a significant evolutionary step towards increased vocal complexity in birds.
Movies and TV Influence Tobacco Use in India: Findings from a National Survey:
Exposure to mass media may impact the use of tobacco, a major source of illness and death in India. The objective is to test the association of self-reported tobacco smoking and chewing with frequency of use of four types of mass media: newspapers, radio, television, and movies. We analyzed data from a sex-stratified nationally-representative cross-sectional survey of 123,768 women and 74,068 men in India. All models controlled for wealth, education, caste, occupation, urbanicity, religion, marital status, and age. In fully-adjusted models, monthly cinema attendance is associated with increased smoking among women (relative risk [RR]: 1·55; 95% confidence interval [CI]: 1·04-2·31) and men (RR: 1·17; 95% CI: 1·12-1·23) and increased tobacco chewing among men (RR: 1·15; 95% CI: 1·11-1·20). Daily television and radio use is associated with higher likelihood of tobacco chewing among men and women, while daily newspaper use is related to lower likelihood of tobacco chewing among women. In India, exposure to visual mass media may contribute to increased tobacco consumption in men and women, while newspaper use may suppress the use of tobacco chewing in women. Future studies should investigate the role that different types of media content and media play in influencing other health behaviors.
Animals constantly detect and encode the location of sound sources in the environment. In order to determine the location of sounds in the horizontal plane, or azimuth, the auditory system employs the interaural time differences (ITDs) that arise when sound reaches one ear before the other. Given the tiny time differences involved, animals are remarkably accurate at localizing sounds. The range of time differences that are useful to the animal depends on the head size--for humans, it's about 600 µs, for gerbils about 150 µs. Humans and barn owls are both localization champions, with an ability to resolve sounds about 2° apart [1]. The task is easier for humans than for barn owls, because our heads are bigger (we have more microseconds per degree of azimuth), but all localizing animals detect time differences on the order of tens of microseconds. This temporal accuracy is remarkable, especially considering that individual neurons fire action potentials that can last a millisecond or more in duration.
Clinical trials conducted in developing countries differ in many respects to those carried out in the West; for example, they are usually conducted in vulnerable populations, focus mainly on infectious diseases, and often have severe endpoints. In these regions, trial capacity lags behind that of wealthier nations, particularly in terms of the ability of research sites to lead broad and independent clinical research programmes. Product development trials are important for the registration of new treatments and vaccines, yet do not leave sites with the skills to run their own trials, as protocol design, operational planning, and data management are typically conducted remotely by the sponsor. There is also a need for more disease management trials to examine and then improve health outcomes, but the capacity to design and execute such studies is often absent. The process of increasing clinical trial capacity should be led by the research sites and tailored to their needs, as trial methods and guidelines need to be appropriately designed and crafted to be fit for purpose in the developing country context. We discuss the need to address the deficit in capacity and training and propose a collaborative solution for identifying the gaps and then designing methods, guidance, and sharing approaches to make clinical trials less daunting and cumbersome, particularly when being planned for resource-limited settings.
The Centennial of the Discovery of Chagas Disease: Facing the Current Challenges:
One hundred years after Carlos Chagas' discovery [1] WHO defines Chagas disease as one of the most important infectious diseases of poverty. Beyond its biological determinants (interplays among the parasite, vector, and human), the social determinants of Chagas disease are of utmost importance; poor housing and working conditions, low salaries, and malnutrition are directly linked to Chagas disease in Latin American [2]. This article highlights the current state on research and innovation related to control and care of Chagas disease, as well as the challenges for the next decade.
Pay-for-performance is an increasingly popular approach to improving health care quality, and the US government will soon implement pay-for-performance in hospitals nationwide. Yet hospital capacity to perform (and improve performance) likely depends on local resources. In this study, we quantify the association between hospital performance and local economic and human resources, and describe possible implications of pay-for-performance for socioeconomic equity. We applied county-level measures of local economic and workforce resources to a national sample of US hospitals (n = 2,705), during the period 2004-2007. We analyzed performance for two common cardiac conditions (acute myocardial infarction [AMI] and heart failure [HF]), using process-of-care measures from the Hospital Quality Alliance [HQA], and isolated temporal trends and the contributions of individual resource dimensions on performance, using multivariable mixed models. Performance scores were translated into net scores for hospitals using the Performance Assessment Model, which has been suggested as a basis for reimbursement under Medicare's "Value-Based Purchasing" program. Our analyses showed that hospital performance is substantially associated with local economic and workforce resources. For example, for HF in 2004, hospitals located in counties with longstanding poverty had mean HQA composite scores of 73.0, compared with a mean of 84.1 for hospitals in counties without longstanding poverty (p<0.001). Hospitals located in counties in the lowest quartile with respect to college graduates in the workforce had mean HQA composite scores of 76.7, compared with a mean of 86.2 for hospitals in the highest quartile (p<0.001). Performance on AMI measures showed similar patterns. Performance improved generally over the study period. Nevertheless, by 2007--4 years after public reporting began--hospitals in locationally disadvantaged areas still lagged behind their locationally advantaged counterparts. This lag translated into substantially lower net scores under the Performance Assessment Model for hospital reimbursement. Hospital performance on clinical process measures is associated with the quantity and quality of local economic and human resources. Medicare's hospital pay-for-performance program may exacerbate inequalities across regions, if implemented as currently proposed. Policymakers in the US and beyond may need to take into consideration the balance between greater efficiency through pay-for-performance and socioeconomic equity.
Closing the Gaps: From Science to Action in Maternal, Newborn, and Child Health in Africa:
The previous papers in the PLoS Medicine series [1],[2] demonstrate that the technical basis for improving maternal, newborn, and child health (MNCH) in sub-Saharan Africa is largely known, but too often policy and practice are not well informed by science. There are two distinct aspects to this "gap." First there is a "science to policy and practice" gap. Accumulated scientific research on the severity of MNCH problems and strategies to promote MNCH has, at least in part, failed to ensure that MNCH reaches the domestic policy agendas of African countries, and stays there. Furthermore, local, context-specific evidence frequently is not applied in planning and programming interventions to address MNCH. Second there is a "policy to practice" gap: even where clear policy commitments to MNCH are made, there may be substantial challenges to getting such policies implemented. These include challenges related to stakeholder management through the implementation process and challenges associated with the negotiation of health system constraints. Many African countries face weakened health systems characterized by human resource shortages, dysfunctional drug supply systems, decaying health infrastructure, and weak supervisory and governance mechanisms. Consequently, the global community is currently strongly focused on strengthening health systems [3] so that they can provide adequate platforms for the delivery of a range of services, including MNCH.
Evolution is iffy business. Between one generation and the next, the millions or billions of base pairs that make up an organism's genetic material go through subtle but sometimes significant changes, with bits added, deleted, and moved around in the off chance that the new combination may serve its owner better than the previous one did its parents. Clearly some do--we are here, and so are nematodes, giraffes, jellyfish, and dandelions, all cut from the same cloth and shaped by such random alterations. But far many more do not. The road to biodiversity is littered with the fleeting memory of genetic remixes that rendered their short-lived owners incapable of survival.
Improving Bioscience Research Reporting: The ARRIVE Guidelines for Reporting Animal Research:
In the last decade the number of bioscience journals has increased enormously, with many filling specialised niches reflecting new disciplines and technologies. The emergence of open-access journals has revolutionised the publication process, maximising the availability of research data. Nevertheless, a wealth of evidence shows that across many areas, the reporting of biomedical research is often inadequate, leading to the view that even if the science is sound, in many cases the publications themselves are not "fit for purpose," meaning that incomplete reporting of relevant information effectively renders many publications of limited value as instruments to inform policy or clinical and scientific practice [1]-[21]. A recent review of clinical research showed that there is considerable cumulative waste of financial resources at all stages of the research process, including as a result of publications that are unusable due to poor reporting [22]. It is unlikely that this issue is confined to clinical research [2]-[14],[16]-[20].
Reporting Animal Studies: Good Science and a Duty of Care:
Estimates of the number of non-human animals used in research vary between 10 million and 50 million [1],[2]. As a publisher, we receive submissions from scores of research groups in numerous different countries that report experimental results or observational data about a huge variety of organisms. Each field, each location, each type of experiment, and each organism may carry a different set of standards governing how the research is approved at an institutional or national level and how the study is reported. Despite this eclectic mix of guidelines and standards, many species used in research are not regulated in any formal manner.
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