 This month in Science Roundup:
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  Spotlight on BiodiversityIn October 2010, scientists, nongovernmental organizations, and politicians will meet at the Convention on Biological Diversity (CBD) to assess the current condition of global biodiversity and to agree on priorities for its future conservation. In the 10 Sep 2010 Science, a Review article and special News Focus section discussed the issues at stake. Rands et al. reviewed recent patterns of biodiversity conservation, highlighting successes, as well as current and future threats. They argue that biodiversity should be treated as a public good -- with responsibility for its conservation integrated across sectors of society and government -- rather than be confined to the business of environmental agencies. In the News Focus section, E. Stokstad looked at new targets being set by the CBD in light of the failure to meet its previous goal of slowing biodiversity loss by 2010; E. Pennisi explained how botanic gardens are contributing to plant conservation, from sorting out plant names to cataloging seeds and growing threatened species (listen to the related podcast interview); and D. Normile highlighted steps that Indonesia is taking to preserve its forests and its biological heritage. Stem Cell Expansion Hematopoietic stem cell (HSC) transplants save tens of thousands of lives each year, but the procedure's full clinical potential has been limited by the ability to expand these cells ex vivo. In the 10 Sep 2010 Science (published online 5 Aug 2010), Boitano et al. reported the promising discovery of a small molecule called StemRegenin1 (SR1) that promotes robust expansion of human HSCs in culture (see the related Perspective by G. Sauvageau and R.K. Humphries). To find this molecule, the researchers screened a large drug library of some 100,000 small molecules, and then developed an assay based on primary HSCs enriched for primitive progenitors (cells that express the cell surface protein CD34). Treatment of HSCs with SR1 led to a 50-fold increase in cells expressing CD34 cells in culture, and a 12- to 17-fold increase in the number of transplanted HSCs capable of long-term repopulation in immunodeficient mice. Gene expression studies further revealed that SR1 acts by antagonizing the aryl hydrocarbon receptor, a transcription factor that induces expression of drug-metabolizing enzymes and has also been implicated in blood cell development. The findings may help improve clinical outcomes and expand the applications of HSC therapies.  Lunar Reconnaissance NASA's Lunar Reconnaissance Orbiter reached lunar orbit on 23 June 2009. Global data acquired since then, described in three Reports in the 17 Sep 2010 Science, are helping researchers better understand the impact history of the Moon and the geologic processes that have shaped it. Using measurements from the Lunar Orbiter Laser Altimeter, Head et al. produced a catalog of large lunar impact craters (more than 20 kilometers in diameter) and analyzed their distribution and population characteristics. In the lunar highlands, large impact craters have obliterated pre-existing craters of similar size, implying that crater counts in this region cannot be used effectively to determine the age of the underlying terrain. In addition, crater counts based on the global dataset indicate that the nature of the Moon's impactor population has changed over time. Greenhagen et al. and Glotch et al. analyzed data from the Diviner Lunar Radiometer Experiment, which analyzes chemical composition by reading the lunar soil's infrared emissions. They identified lunar soils rich in oxygen-bearing silicate minerals in a wide variety of landforms, which suggests the existence of more complex igneous processes on the Moon than previously assumed. A ScienceNOW story by P. Berardelli highlighted the findings. Optical Clocks and Relativity According to Einstein's theory of relativity, space and time are not fixed concepts, but instead are relative to an observer and their frame of reference. In the so-called twin paradox, a twin sibling who travels on a fast-moving rocket ship returns home younger than the other twin, and this "time dilation" can be quantified by comparing the tick rates of identical clocks that accompany the traveler and the stationary observer. Another consequence of Einstein's theory is that clocks run more slowly near massive objects like Earth owing to their gravitational fields. For example, if two identical clocks are separated vertically by 1 km near the surface of Earth, the higher clock emits about three more second-ticks than the lower one in a million years. In the 24 Sep 2010 Science, Chou et al. demonstrated the effects of relativity at distances and timeframes more familiar to our daily lives using super-accurate optical atomic clocks, which exploit the fact that the electrons in an atom occupy "states" with distinct energies and can hop between two states by emitting or absorbing electromagnetic waves of a set frequency (see the ScienceNOW story by A. Cho). By comparing two such clocks connected by a 75-meter length of optical fiber, the team was able to detect relativistic time dilation due to velocities of several meters per second and, separately, due to a change in height of just 33 centimeters meters (listen to the related podcast interview with lead author Chin-wen Chou). The technique might be useful in geodesy (measuring the size and shape of the Earth), hydrology, and space-based tests of fundamental physics.  Return of the Florida PantherFifteen years ago, Florida panthers (also called cougars, pumas, or mountain lions) were in dire straits: Only about 20 to 25 of the beleaguered predators roamed in southern Florida, and observations of reduced genetic variation due to inbreeding, heart defects, reproductive problems, and increased susceptibility to disease led researchers to predict a 95% likelihood that the species would be extinct within two decades (see the Perspective by C. Packer). But in 1995, biologists invigorated the panthers with some fresh blood, releasing eight female cougars from Texas into south Florida. In the 24 Sep 2010 Science, Johnson et al. provide a comprehensive analysis showing how the genetic reinforcement has dramatically improved the health of the panthers ( see the related ScienceNOW story by E. Stokstad). By comparing genetic data from 591 panthers sampled between 1978 and 2009, the researchers show that Texas-Florida hybrid offspring have now replaced the original inbred stock. Moreover, panther numbers have increased threefold, the level of genetic heterozygosity (having different versions of the same gene) has doubled, survival and fitness measures have improved, and inbreeding has declined. While the improvements are promising, the researchers stress that continued habitat loss, persistent inbreeding, and infectious agents pose new dilemmas that will require continued commitment to preserve the Florida panther for more than the next few decades. Antimalarial Drug Candidate Malaria causes more than 800,000 deaths each year, and despite the development of effective treatments, the malaria parasite continues to build resistance to many of the leading drugs. Thus, there is an urgent need for new drugs that can overcome the challenges of resistance. In a Research Article in the 3 Sep 2010 Science, Rottmann et al. reported on a promising new candidate. Using traditional screening methods involving whole malaria parasites and cells, the team identified a class of compounds, called spiroindolones, with potent activity against the malaria parasite Plasmodium falciparum. A particularly promising spiroindolone, NITD609, meets all of the criteria for an ideal antimalarial drug: it kills the parasite's blood stages; it is active against drug-resistant parasites; it is nontoxic; and it is compatible with once-daily oral dosing. Moreover, the researchers found that this compound acts by rapidly suppressing protein synthesis in the parasite -- a mechanism of action distinct from that of existing antimalarial drugs. An accompanying Perspective by T.N.C. Wells discussed the merits of parasite-based versus molecular screening approaches to antiparasitic drug development, and a News Focus by M. Enserink profiled François Nosten, one of the paper's co-authors, who has worked to treat and study malaria in Thailand for 25 years.  Aerosol AnalysesAtmospheric aerosols -- microscopic liquid or solid particles suspended in Earth's atmosphere -- can harm human health as well as influence climate by absorbing and reflecting solar radiation and modifying cloud formation. Whereas health-related monitoring typically focuses on measuring aerosol mass concentrations, a host of additional variables come into play when dealing with climate. In the 17 Sep 2010 Science, two studies shed new light on aerosol distribution and characteristics in relatively untested regions (see the Perspective by U. Baltensperger). In a Research Article, Clark and Kapustin used satellite-retrieved samples and climate models to examine vertical atmospheric profiles collected above the Pacific Ocean, where air quality is affected by the transport of polluted air from the west. They found that variables associated with carbon monoxide from combustion -- including enhanced light scattering, aerosol mass, and aerosol number -- were greatly enhanced, and in some cases, exceeded values in unperturbed regions by more than an order of magnitude. In a separate Report, Pöschl et al. studied one such unperturbed region: the atmosphere above the Amazon Basin, which, during its rainy season, is thought to approximate conditions in the pre-industrial era. Using a variety of microscopy and spectroscopy techniques, the researchers determined that the aerosols above the Amazon are derived mostly from gaseous biogenic precursors, plants, and microorganisms, and particle concentration is orders of magnitude lower than in polluted continental regions. Networks and Behavior An important question for policy-makers is how to communicate information -- for example, about a public health intervention -- and promote behavior change most effectively across a population. In a Report in the 3 Sep 2010 Science, Centola investigated how social networks affect the spread of behavior using a controlled experimental approach (listen to the related podcast feature). He created an Internet-based health community containing 1,528 participants recruited from health-interest Web sites, who were subsequently matched to other participants, or "health buddies," in the community. Participants were assigned to either a clustered-lattice network (characterized by fewer, but more redundant ties linking each participant's neighbors to one another) or a random network setup. A "seed" participant was randomly selected in each group, and that seed's health buddies received a message encouraging them to register for an online health forum. Every time a participant adopted that behavior and registered for the health forum, a message was sent out to that participant's buddies, and so on. The behavior was found to spread farther and faster across clustered-lattice networks than random ones, an indication that individual adoption was much more likely when participants received social reinforcement from multiple neighbors in the social network. Centola suggests that public health interventions aimed at the spread of new health behaviors -- such as improved diet, regular exercise, or condom use -- may thus do better to target clustered residential networks rather than casual contact networks. Introspection and the Brain The ability to introspect -- or think about your thinking -- is a key aspect of human consciousness, but little has been known about the biological basis of this ability. In the 17 Sep 2010 Science, Fleming et al. used a visual decision-making task to help measure individuals' introspective abilities, and to determine whether the variability between individuals is associated with a distinct neural basis. Participants were first asked to choose which patch in a series of images was brightest, with the difficulty of each trial adjusted to maintain equal performance levels across individuals. To measure introspection, participants were then asked to rate how confident they were in each of their decisions: the better the correlation between their confidence and accuracy, the better their introspective abilities. The researchers then related this measure to participants' brain scans obtained by magnetic resonance imaging. They found that introspective ability correlates positively with gray -matter volume in the anterior prefrontal cortex -- a brain region that shows marked evolutionary development in humans -- and with the integrity of white matter (neuronal fibers) connected with this area. The findings may help scientists understand how brain injuries affect reflection and introspection, and how to tailor treatments to patients who may not understand their own conditions. An accompanying Perspective by H. Lau and B. Maniscalco highlighted the Report.  Sunflower Origins The sunflower family, or Asteraceae -- which also includes daisies, chrysanthemums, lettuce, and artichokes -- is the most diverse family of flowering plants on Earth in terms of numbers of genera and species and widespread distribution. Where the Asteraceae first evolved and how they spread, however, is not well understood, in part because researchers have found relatively few fossils. Now, in a Brevium in the 24 Sep 2010 Science, Barreda et al. describe an unusually well-preserved new fossil that sheds light on the history of this successful plant family and adds to evidence that it originated in southern South America about 50 million years ago. While most known fossils of this family have been pollen grains, the new find shows several hallmark features of the Asteraceae including a capitulum -- a cluster of sessile flowers crowded onto a receptacle -- and leaflike structures called phyllaries surrounding the flowers. The fossil was found in northwestern Patagonia in southern South America, in rocks that are about 47.5 million years old. The researchers propose that an ancestral stock of Asteraceae may have arisen in the southern supercontinent of Gondwana before it broke apart into South America, Africa, India, Australia, and Antarctica. An accompanying Perspective by T. Stuessy noted that it is still unclear how the family quickly colonized the entire planet and became so incredibly diverse. Martian Carbon Dioxide Although the ice of a deeply frigid martian winter wrecked NASA's Mars Phoenix Lander last year, data it returned before its demise continue to shed new light on the planet's geologic past. In the 10 Sep 2010 Science, Niles et al. report, based on 2008 data on the isotopic composition of atmospheric carbon dioxide, that Mars's atmosphere has been heavily influenced by volcanic outgassing -- perhaps up to the very recent geologic past. In the planet's early days, a then-fierce solar wind preferentially removed the lighter, carbon-12 isotope from the atmosphere, leaving more of the heavier carbon-13 isotope. However, Niles et al. found that the current atmospheric carbon is lighter than expected, which suggests a contribution from volcanic outpourings from the planet's rocky interior whose carbon is isotopically lighter. Isotopic oxygen measurements further suggest that the carbon dioxide has been interacting with liquid water. Combined with previous work on martian meteorites, the results also suggest that low-temperature water-rock interaction has been dominant through martian history and that carbonate formation is active and ongoing. A related News story by R.A. Kerr highlighted the findings. In Science Signaling
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