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[1] Evolution: Whale of a species (pp278-281)
A new species of whale has been discovered.
Eight specimens caught by Japanese whaling research vessels in the late 1970s have been identified by Shiro Wada, Masayuki Oishi and Tadasu K. Yamada as belonging to a new species of baleen whale (Balaenoptera omurai). They report in this week's Nature that their analysis has also separated the very similar Bryde's whale and Eden's whale into distinct species.
There were, until this new discovery, six known living species of baleen whale, the most familiar being the smallest, the common minke whale (Balaenoptera acutorostrata). Now there are eight baleens.
Estimates of the number of the Earth's species yet to be discovered vary wildly but all are high — of the order of 10 million to more than 100 million. These are thought to be mainly fish, fungi, microbes and insects. A new mammal species is a rarity, especially one the size of a whale.
[2] Evolution: Pinpointing dodo's date with extinction (p245; N&V)
The dodo's swan song was probably about 30 years later than the date of its last reliable sighting in 1662, commonly used as a marker for its extinction. So suggests a Brief Communication in this week's Nature.
Estimating the date of demise of a species with any accuracy is difficult, as rare individuals may survive undetected for years after the last sighting. Concerned that this was the case with the hapless dodo (Raphus cucullatus), David L. Roberts and Andrew R. Solow carried out a statistical test based on the timings of the last ten recorded sightings to estimate the actual point of extinction. Their statistical approach indicates that the last of the ungainly flightless birds probably died not in 1662 but 28 years later, in 1690.
Stuart Pimm discusses the implications of this technique for calculating the extinction dates of other deceased species, such as the long-dead dinosaurs, as well as currently endangered ones, in an accompanying News and Views article.
[3] Climate: Volcanoes make El Niño events more likely (pp274-278; N&V)
By spewing vast quantities of dust and greenhouse gases into the atmosphere, large volcanic eruptions can leave a fingerprint on global climate. In this week's Nature, J. Brad Adams of the University of Virginia and colleagues show that the eruption of tropical volcanoes may double the likelihood that an El Niño event will begin the following winter. As well as aiding climate forecasters, these observations might help scientists anticipate the response of the Earth's climate system to human influences.
El Niño events, which cause drought in some parts of the world and increased rainfall in others, are natural oscillations in climate that recur every 3"11 years. For an El Niño event to start, sea surface temperature in the western tropical Pacific Ocean must be warmer than usual. The climate effects of volcanic eruptions could kick-start such a change. Adams and colleagues have investigated this possibility by comparing records of volcanic activity and El Niño events in the historical past, dating back to the mid-seventeenth century.
Volcanic eruptions are not only recorded historically but also revealed by deposits of dust preserved in polar ice. El Niño oscillations are also documented in historical records and in various geological climate indicators, such as tree rings, coral growth and ice cores. A statistical comparison of these records, say the researchers, shows that tropical eruptions seem to be followed by El Niño events significantly more often than can be accounted for by mere chance. They think that the eruptions produce a veil of dust in the lower stratosphere, which exerts a cooling influence by reflecting the Sun's rays. Somewhat counter-intuitively, the complex interactions between the atmosphere and the oceans convert this into the kind of tropical ocean warming that makes an El Niño event more likely.
Shanaka de Silva emphasizes in an accompanying News and Views article that it will be a "tall order" to establish in more detail the statistical link between El Niño events and volcanoes.
[4] Developmental Biology: Gender benders (pp291-295; N&V)
A painstaking triple-gene-knockout study in mice reported in this week's Nature reveals new and unexpected roles for the insulin receptor family in male sexual development. It moves researchers a step closer to understanding how the Y chromosome gene Sry drives the development of testes.
Luis F. Parada and his colleagues produced mouse embryos that lacked the function of all three members of the insulin receptor family of genes; these genes regulate various aspects of growth and metabolism. None of the three single-knockout mouse strains had defects in sexual development.
Triple-knockout embryos with one X and one Y chromosome showed complete male-to-female sex reversal very early on in development. Their gonads resembled normal XX ovaries in appearance and in the expression of ovary-specific genes, but lacked the expression of testis marker genes.
It seems that the three insulin receptors act upstream of Sry to control sex determination but are not absolutely required for Sry expression, comments Peter Koopman in an accompanying News and Views article.
[5] Ecology: Scarab beetles trade heat for pollen (pp243-244)
Adult scarabs cut their energy bills by hanging around inside heat-producing flowers. The Cyclocephala colasi beetles of French Guiana need to generate 2- to 4.8-times more energy to eat and mate outside a Philodendron solimoesense flower than inside, reports a Brief Communication in this week's Nature. Partly because the insects are small, the hike in metabolic rate required to raise their temperature can be huge.
"This finding indicates that heat produced by the flower constitutes an important reward to pollinators," conclude Roger Seymour and colleagues. Thermogenesis in flowers fertilized by large scarabs is widespread in tropical forests. Around 900 plant species are visited by more than 220 beetle species. Such exchanges may have been even more important during the early evolution of the flowering plants.
[6] Genetics: A blue day for plants (pp302-306)
A blue-light photoreceptor, FKF1, is essential for day length measurement in the model plant Arabidopsis, researchers report in this week's Nature. Its expression late in the afternoon is critical for the induction of key regulators of flowering, say Steve A. Kay and his colleagues.
In plants, many vital processes such as photosynthesis are affected by the day/night cycle. To control these processes, plants have a circadian clock that coordinates the expression of key regulatory genes rhythmically. The clock also regulates seasonal processes such as flowering by measuring day length.
By characterizing a range of mutants with altered flowering patterns, the individual steps involved in this complex seasonal time-keeping system are beginning to be defined.
[7] Physics: How nanoparticles get their spots (pp271-274)
Like mud in a lake bed fragmenting into a complex pattern of cracks as water evaporates, so tiny, nanometre-scale particles clump together into various patterns as a suspension of them dries out. (A nanometre is a millionth of a millimetre.) This aggregation process may give rise to useful, spontaneously organized structures, such as complicated webs of material or clusters of more or less equal size and spacing. In this week's Nature, Eran Rabani and co-workers describe a simple model that can explain and predict the structures formed by the drying-induced aggregation of nanoparticles.
The researchers represent the system as a chequerboard grid. Each square is occupied by a solvent molecule, part of a nanoparticle (a cluster of squares represents a whole nanoparticle), or is empty (like a gas). Rabani and colleagues show that, depending on the type of solvent and nanoparticle and the rate of evaporation, their model can generate several different kinds of dry aggregate patterns. Some of these have been seen experimentally; the others, say the researchers, are structures that might be produced if the right experimental conditions are achieved. The model may help experimentalists select a certain kind of nanoparticle pattern from the palette available.
[8] Plant science: Flower arrangement (pp255-260)
In this week's Nature Cris Kulhemeier and colleagues show that the regulation of leaf and flower arrangement around plant stems depends on the activity of specific transport proteins for the plant hormone auxin. These proteins carry auxin towards the growing tip through the shoot's outer cell layers. Existing leaf positions influence auxin distribution to define future leaf positions.
The regular spiral arrangement of leaves and flowers around a plant's stem — phyllotaxis — follows the rules of the Fibonacci series, a sequence of numbers in which each term is the sum of the two terms preceding it. Computer simulations have successfully modelled the process, but the molecular mechanisms underpinning it had remained elusive.
[9] Ecology: Food webs in the picture (pp282-285)
Ecologists have theorized that plants and animals organize themselves, or at least become organized, into small groups. These groups are known as compartments, with strong interactions within compartments and weak interactions between them. Knowledge of how these compartments develop in food webs is an important factor in understanding biodiversity and ecosystem stability. Recent collaborations between ecologists and sociologists have turned up strong similarities between social networks and food webs.
Now Ann Krause and colleagues use methods developed for mapping social interactions to identify the food compartments in food webs. Pictures of the results reveal the tangled relationships between plant and animal species, and provide a model in which the possible effects of ecological change can be tested.
[10] Medicine: Biofilm barrier (pp306-310)
The lungs of cystic fibrosis patients are often colonized by the pathogen Pseudomonas aeruginosa, and the infection can be particularly difficult to treat. The bacterium's resistance to antibiotics seems to be linked to its propensity to grow in communities embedded in a protective sugar matrix or biofilm. Bacterial cells cocooned in this way can be up to 1,000 times more resistant to antibiotics than free-living cells.
Now the properties of a newly isolated mutant of P. aeruginosa outlined by George A. O'Toole and colleagues in this week's Nature suggest, however, that biofilms are not simply a diffusion barrier. The mutant gene codes for a glucan that binds specifically to the antibiotic tobramycin, holding it within the biofilm before it can reach its site of action.
This suggests that co-treatment, with an antibiotic and a compound that targets a specific glucan in the biofilm, might help to overcome antibiotic resistance.
[11] Insight into hydrocarbons research
This week's Nature Insight rounds up the diverse scientific challenges facing hydrocarbons research with a clutch of review articles exploring the following issues.
Naturally formed reservoirs of hydrocarbons occur in a variety of geological contexts, notably as oil and gas, and are exploited to satisfy the majority of our energy needs. These resources are finite, yet the demand for fossil fuels is growing apace. Meanwhile, fossil fuels are strongly implicated as the main driver of climate change.
Until we find economically viable alternative energy sources, research is needed to exploit diminishing supplies of hydrocarbons. A rethink is required concerning the location and nature of untapped reserves. The reservoirs that could be accessed easily were exhausted long ago, and greater ingenuity is required to both locate and extract the deposits of hydrocarbons that remain. Industry faces a host of unfamiliar scientific challenges as it extends its reach into increasingly hostile environments, such as deep water, and into previously ignored classes of hydrocarbon — such as gas hydrates.
So, despite the maturity of the industry as a whole, its academic needs have never been greater. The modern hydrocarbon engineer increasingly draws on physics, chemistry and biology to understand and successfully exploit previously intractable reservoirs.
PDFs of all the Insight papers can be found on http://press.nature.com from Friday
[12] And Finally"¦: The unified fielder theory (pp244-245)
A fielder needs to keep two angles in mind when running to catch a ball, suggest Peter McLeod and colleagues in a Brief Communication in this week's Nature. The fielder can then move to make the catch in a smooth, evenly paced arc, with a minimum of acceleration.
The two angles are the vertical elevation to the ball, and the horizontal angle towards the ball relative to the fielder's starting point. When the optimum path is followed, the first angle will increase at a decreasing rate, while the second will increase at a constant rate. So by satisfying these criteria, a fielder can intercept the ball without explicitly choosing a direction or speed in which to run.
McLeod and colleagues simulated fielders following these rules, and found that their trajectories closely matched those of real fielders. Children may learn these rules by comparing the experience of watching objects that hit them with what happens when they watch an object that misses them—and then recreating the hits to catch a falling ball, the researchers suggest.
ALSO IN THIS ISSUE"¦
[13] Eya protein phosphatase activity regulates Six1"Dach"Eya transcriptional effects in mammalian organogenesis (pp247-254; N&V)[14] A collimated, high-speed outflow from the dying star V Hydrae (pp261-264; N&V)[15] Demonstration of an all-optical quantum controlled-NOT gate (pp264-267)[16] Direct observation of attosecond light bunching (pp267-271)[17] Eyes absent represents a class of protein tyrosine phosphatases (pp295-298)[18] The transcription factor Eyes absent is a protein tyrosine phosphatase (pp299-302)[19] Transposon silencing in the Caenorhabditis elegans germ line by natural RNAi (pp310-314)
GEOGRAPHICAL LISTING OF AUTHORS"¦
The following list of places refers to the whereabouts of authors on the papers numbered in this release. For example, London: 4 - this means that on paper number four, there will be at least one author affiliated to an institute or company in London. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.
AUSTRALIAAdelaide: 5Brisbane: 15
FINLANDHelsinki: 4
FRANCEToulouse: 5Versailles: 8
GERMANYGarching: 16Tubingen: 8
GREECEHeraklion (Crete): 16
ISRAELTel Aviv: 7
JAPANMorioka: 1Tokyo: 1Yokohama: 1
THE NETHERLANDSUtrecht: 19
SWITZERLANDBern: 8Geneva: 4
UNITED KINGDOMBrighton: 12Nottingham: 8Oxford: 12Richmond: 2
UNITED STATES OF AMERICA
California Berkeley: 7 La Jolla: 6, 13 Los Angeles: 14 Pasadena: 14 Stanford: 6, 18Colorado Boulder: 3Georgia Valdosta: 14Illinois Urbana: 15Maryland Rockville: 18 Solomons: 9Massachusetts Boston: 13 Cambridge: 7, 10, 14, 18 Charlestown: 10 Woods Hole: 2Michigan Ann Arbor: 9 East Lansing: 9Montana Bozeman: 10New Hampshire Hanover: 10New Jersey Princeton: 14New York New York: 4, 7, 13Ohio Cincinnati: 17Texas Dallas: 4 Houston: 17Virginia Charlottesville: 3
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