bluuebunny/crossref_metadata_2025 huggingface dataset:
A Revision of Siphoneugena Berg
Authors: Proença Carolyn
Published: April 2010

Siphoneugena Berg (Myrtaceae, Myrteae) is a small eugenioid genus with eight species ranging from Puerto Rico to Northern Argentina with the centre of diversity in Southeastern Brazil. Keys to the species and varieties are provided, as well as synonyms, descriptions, illustrations and a map of geographical occurrence. Two new taxa are described from Brazil: Siphoneugena guilfoyleiana C. Proença, the only species to occur in sandy maritime vegetation on the Ilha do Cardoso, state of São Paulo and S. densiflora Berg var. cipoensis C. Proença, an endemic of the Serra do Cipó mountain range in the state of Minas Gerais. A new combination S. dussii (Krug & Urban) C. Proença based on Marlierea dussii, is made for a species that grows in Venezuela, Guyana, Surinam and the West Indies. This study confirms current opinions as to the low taxonomic value of open versus closed calyces in establishing natural genera within the Myrtaceae.Revisão de Siphoneugena BergSiphoneugena Berg (Myrtaceae, Myrteae) é um pequeno gênero eugenióide que se distribuide Porto Rico ao Norte da Argentina com centro de diversidade no Sudeste do Brasil. São fornecidas chaves para o gênero e para as oito espécies e duas variedades, bem como sinonimia completa, descrições, ilustrações, e mapa de distribuçião geográfica. Dois novos taxons brasileiros são descritos: Siphoneugena guilfoyleiana C. Proença, que ocorre nas restingas da Ilha do Cardoso (São Paulo) e S. densiflora Berg var. cipoensis C. Proença, endêmica da Serra do Cipó (Minas Gerais). A nova combinação S. dussii (Krug & Urban) C. Proença, baseada em Marlierea dussii é feita para uma espécie da Venezuela, Guiana, Suriname e Antilhas. Este trabalho confirma o baixo valor taxonômico da forma de antese (botões florais fechados ou abertos) na delimitação de gêneros naturais em Myrtaceae.
A Review of the infraspecific taxa of Paeonia Suffruticosa Andrews
Authors: Haw S. G. , Lauener L. A.
Published: April 2010

A review of the infraspecific taxa of Paeonia suffruticosa Andr. is presented. Three subspecies are recognized, subsp. suffruticosa, subsp. spontanea (Rehder) Haw & Lauener stat. nov., and subsp. rockii Haw & Lauener, subsp. nov., with one further doubtful subspecies. The distinguishing features of all the subspecies are described.
Four new species of Zingiberaceae from Borneo
Authors: Smith R. M.
Published: April 2010

Four new species of Bornean Zingiberaceae are described:- Amomum sceletescens, Hedychium borneense from Sabah, H. lineare which occurs in Sabah, Sarawak and Kalimantan, and Elettariopsis kerbyi from the Gunong Mulu National Park in Sarawak.
EJB volume 48 issue 1 Cover
Authors: Editor Journal
Published: April 2010

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Notes relating to the Flora of Bhutan: XVII. Zingiberaceae
Authors: Smith R. M.
Published: April 2010

A new species of Hedychium, H. griersonianum, is described and its relationship to H. ellipticum discussed. Two new combinations are made in Stahlianthus, S. inrolucratus (King ex Baker) R. M. Smith, for which a lectotype is selected, and S. andersonii (Baker) R. M. Smith.
New taxa and transfers in Indian Umbelliferae
Authors: Mukherjee P. K. , Constance L.
Published: April 2010

Two new species from the eastern Himalaya are described, one in Physospermopsis and one in Sinocarum. Additionally, new combinations are proposed for the Indian area in Bupleurum. Schulzia, Meeboldia, Sinocarum, Pimpinellu, and Angelica.
Cytological observations inAlbuca, including a survey of polymorphic variation in the Sat-chromosome pair
Authors: Jong Kwiton
Published: April 2010

Chromosome numbers for 14 South African species ofAlbucaL. (Liliaceae) have been determined. Ten of these are first reports, including counts for three new species. Members of all three sections of the genus are represented in this study, and all have a diploid number of 2n = 18. No polyploids or dysploids were encountered in this survey. There is no evidence that the sectional subdivisions ofAlbucacan be readily distinguished on differences in basic chromosome number or karyotype, for all taxa are characterized by a common basic number of x = 9 and by a remarkably uniform, strongly asymmetric and bimodal complement of three long chromosomes and six markedly shorter ones. Special attention is focused on the hitherto largely overlooked variability of the longest chromosome pair which, in a large proportion of the species examined, shows heterozygous variation in the size, morphology and stainability of its satellite and in some cases, also in the short chromosome arm that bears it. This unusually high incidence of polymorphism, and the diversity of form observed in this satellited (Sat-chromosome) pair is discussed in relation to similar patterns reported elsewhere.
EJB volume 53 issue 3 Cover and Front matter
Authors: Editor Journal
Published: April 2010

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Cortinarius subgenus Phlegmacium section Phlegmacium in Europe: Descriptive part
Authors: Brandrud T. E.
Published: April 2010

The taxonomy of Cortinarius subgen. Phlegmacium sect. Phlegmacium in Europe is emended to include 17 species, classified in three subsections: Subsect. Triumphantes: C. saginus ( = C. subvalidus), C. triumphans (=C. crocolitus). C. varius (here neotypified). C. variiformis ( = C luteocingulatus), C. tiliae sp. nov., C. pini sp. nov. and C. norrlandicus; Subsect. Arguti: C. argutus (here neotypified), C. fraudulosus var. fraudulosus. C. fraudulosus var. rosargutus comb, nov., C. paracephalixus ( = C. rioussctiae) and C. herculeus: Subsect. Vulpini: C. vulpinus ( = C. rufoalbus. C. fluryi). C. pseudontlpimts, C. maculosus, C. caligatus (=C. crustulinus) and C. aremoricus. Species descriptions are provided, with emphasis on formerly little studied micromorphological characters. Most species are well delimitated and normally easily distinguished from closely related taxa. Their diagnostic characters are presented. The circumscription of a number of the species deviates from the one most frequently used, and many taxa are synonymized. Altogether, 18 species names which have been in use after 1900 are reduced to synonyms. The delimitation of the section towards the neighbouring sect. Phlegmacioides (= Variecolores) is discussed, as well as the typification of the name Phlegmacium.
Forest structure, floristic composition and soils of an Amazonian monodominant forest on maracá Island, Roraima, Brazil
Authors: Nascimento M. T. , Proctor J , Villela D. M.
Published: April 2010

Maracá is a riverine island located in the Rio Uraricoera in Roraima State (Brazil) and has an area of about 100,000ha. A forest type dominated by Peltogyne gracilipes Ducke (Caesalpiniaceae) occurs on Maracá Island on a range of soil types. This study compares the structure, floristic composition and soils of the Peltogyne forest with the most widespread lowland forest type on Maracá. Three 0.25ha plots were set up in each of three forest types: Peltogyne-rich forest (PRF), Peltogyne-pooi forest (PPF) and forest without Peltogyne (FWP). Within each plot all trees (≤ 10cm dbh) were recorded. Seedlings and saplings were sampled in subplots of 2m × 1m (seedlings) and 4m × 4m (saplings). In the PPF and FWP, Sapotaceae were the most important family with the highest relative dominance and relative density values. Caesalpiniaceae showed high values in the PRF and PPF. Licania kunthiana, Pradosia surinamensis and Simarouba amara occurred in the canopy layer in all the forest types. Peltogyne dominated the canopy in the PRF and comprised 20% of stems and 53% of the total basal area of all trees ≥ 10cm dbh, and 91% of the stems and 97% of the total basal area of individuals ≥ 50cm dbh. In PPF, Lecythis corrugata and Tetragastris panamensis were the most abundant species, followed by Peltogyne. In the FWP the most abundant trees (≥ 10cm dbh) were Licania kunthiana and Pradosia surinamensis. In all forest types, the soils were sandy and acid with low concentrations of extractable phosphorus and exchangeable cations, but the soils under PRF were notably richer in magnesium.
Floral biometry, floral rewards and pollen-ovule ratios in some Vicia from Extremadura, Spain
Authors: Olivencia A. Ortega , Ramos S. , Rodríguez T. , Devesa J. A.
Published: April 2010

A biometric study of the flower, floral rewards (nectar and pollen) and pollen-ovule ratios in 14 taxa of Vicia (Fabaceae) from Extremadura (Spain) has been evaluated. Almost all floral characteristics are directly correlated and it has been found that flower size is a good indicator of the reward production, and the pollen-ovule ratios are positively correlated to seed size. A direct correlation between pollen size (volume) and style length has likewise been observed. This may show the importance of the pollen food reserves in sustaining the growth of its pollen tube along the style.
Corydalis in China I: Some new species
Authors: Zhi-Yun Su , Lidén M.
Published: April 2010

Twenty-nine new species of Corydalis (Fumariaceae) from China, mainly from Tibet, Sichuan and Yunnan, are described.
ilk Tree, Guanacaste, Monkey's Earring. A Generic System for the Synandrous Mimosaceae of the Americas. Part 1. Abarema, Albizia and Allies. Rupert C. Barneby & James W. Grimes.
Authors: Hughes C. E.
Published: April 2010

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Polyploidy: a factor in the evolution of Dicerandra Benth. (Labiatae)
Authors: Huck R. B. , Chambers H. L.
Published: April 2010

Chromosome counts are reported for the first time in Dicerandra Benth. (Labiatae), a genus endemic to the south-eastern United States. Representative taxa are tetraploid (n = 16) and hexaploid (n = 24). Diploids were not found. The systematic, phytogeographic and conservation implications of polyploidy in this genus are discussed. The monophyletic nature of the genus is upheld by the discovery that both sections have a presumed base number of x = 8. Hexaploidy has apparently evolved independently in all branches of sect. Dicerandra, but not in sect. Lecontea.
Macromycetes from the state of Paraná, Brazil: 5. Poroid and lamellate boletes
Authors: Watling R. , De Meijer A. R.
Published: April 2010

Nine species of tubulate and two species of lamellate boletes are recognized in the mycota of Paraná State, Brazil, of which five are considered introduced.Gloeocantharellus corneri and a further genus of boletes are noted, the latter based on immature material. These records are new to South America, Brazil or Paraná State. Three new combinations are made in the genus Boletinellus for species previously placed in Gyrodon: Boletinellus exiguus, B. monticola and B. rompelii.
A taxonomic revision of Schisandra section Sphaerostema (Schisandraceae)
Authors: Saunders R. M. K.
Published: April 2010

The classification of Schisandra Michx. sect. Sphaerostema (Blume) Nakai is revised, using multivariate statistical analyses as required. Only two species are recognized, viz. Schisandra plena A.C. Sm. and S. propinqua (Wall.) Baill., following reduction of S. axillaris (Blume) Hook.f. & Thorns, to a subspecies of the latter taxon. Four subspecies are recognized in S. propinqua, viz.: subsp. propinqua (N W India and Nepal); subsp. intermedia (A.C. Sm), stat. nov. (NE India, Burma and Yunnan); subsp. sinensis (Oliv.), stat. nov. (central and southern China); and subsp. axillaris (Blume), comb, et stat. nov. (Java and Bali). The biogeographical origin of the vicariant distribution of S. propinqua is discussed. A key is provided for the identification of taxa, with new taxonomic descriptions.
A revision of the genus Oreorchis (Orchidaceae)
Authors: Pearce N. , Cribb P.
Published: April 2010

A taxonomic revision of Oreorchis is presented. A key to the species and synonymies, descriptions, illustrations and distributions for each taxon are provided. The status of the genera Kitigorchis F. Maek. and Diplolabellum F. Maek. are discussed. The former is redefined as a monotypic genus, with three of the four species included by Maekawa being returned to Oreorchis; the latter is considered congeneric with Oreorchis. Three species, O. angustata, O. aurantiaca and O. nepalensis, are newly described here and O. indica is reduced to varietal status within O. foliosa. Some outstanding problems in the taxonomy of the genus are noted.
New Flora of the British Isles. 2nd edition. Clive Stace, with line drawings mainly by Hilli Thompson.
Authors: McKean D. R.
Published: April 2010

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Systematic studies of Bornean Zingiberaceae I. Amomum in Lambir Hills, Sarawak
Authors: Sakai Shoko , Nagamasu Hidetoshi
Published: April 2010

Twelve species of Amomum (Zingiberaceae) are reported from Lambir Hills, Sarawak, with systematic and ecological notes based on field observations for more than one year. Five species, Amomum angustipetalum, A. bilabiatum, A. calyptratum, A. durum and A. somniculosum, are described as new to science. A key to all species of Amomum in Borneo is provided. The first report of andromonoecy and sexual dimorphism of inflorescence in Zingiberaceae is given for A. polycarpum.
ON PRODUCTS OF PSEUDO-ANOSOV MAPS AND DEHN TWISTS OF RIEMANN SURFACES WITH PUNCTURES
Authors: ZHANG C.
Published: April 2010

Let S be a Riemann surface of type (p,n) with 3p+n>4 and n≥1. We investigate products of some pseudo-Anosov maps θ and Dehn twists tα on S, and prove that under certain conditions the products tkα∘θ are pseudo-Anosov for all integers k. We also give examples that show that tkα∘θ are not pseudo-Anosov for some integers k.
ON CARMICHAEL NUMBERS IN ARITHMETIC PROGRESSIONS
Authors: BANKS WILLIAM D. , POMERANCE CARL
Published: April 2010

Assuming a conjecture intermediate in strength between one of Chowla and one of Heath-Brown on the least prime in a residue class, we show that for any coprime integers a and m≥1, there are infinitely many Carmichael numbers in the arithmetic progression a mod m.
Interaction of Saturn's magnetosphere and its moons: 2. Shape of the Enceladus plume
Authors: Jia Y.‐D. , Russell C. T. , Khurana K. K. , Ma Y. J. , Najib D. , Gombosi T. I.
Published: April 2010

The Saturnian moons in the inner magnetosphere are immersed in a plasma disk that rotates much faster than the moon's Keplerian speed. The interaction of the rotating plasma with the moons results in a disturbance in the Saturnian magnetospheric plasma that depends on the nature of obstacle that the moon represents. In particular at Enceladus, such perturbations in the magnetic field and flowing plasma enable us to infer the 3‐D shape of the Enceladus plume and its outgassing rate. In this paper, we apply our 3‐D magnetohydrodynamic model to extensively study the effects of different plume and disk plasma conditions on the interaction. By finding the best agreement with the observations of two diagnostic flybys, one with its point of closest approach on the upstream side and the other on the downstream side, we determine the plume intensity and configuration. We find that mass loading in the plume is less efficient close to the surface of the moon, where the neutral density is the highest. For E2 and E5, the opening angle of the plume is about 20°, and the plume is tilted toward the corotating direction. The upstream density has a significant effect on the mass loading rate, while its effect on the magnitude of the magnetic perturbation is less significant. An upstream velocity component in the Saturn direction helps to explain the observed magnetic perturbation in the By component and signals the need to consider Enceladus's effect on the global plasma circulation in addition to the local effect. Quantitative comparisons of the simulated and observed interaction are provided.
A multiscale model of partial melts: 1. Effective equations
Authors: Simpson G. , Spiegelman M. , Weinstein M. I.
Published: April 2010

Developing accurate and tractable mathematical models for partially molten systems is critical for understanding the dynamics of magmatic plate boundaries as well as the geochemical evolution of the planet. Because these systems include interacting fluid and solid phases, developing such models can be challenging. The composite material of melt and solid may have emergent properties, such as permeability and compressibility that are absent in each phase alone. Previous work by several authors have used multiphase flow theory to derive macroscopic equations based on conservation principles and assumptions about interphase forces and interactions. Here we present a complementary approach using homogenization, a multiple scale theory. Our point of departure is a model of the microstructure, assumed to possess an arbitrary, but periodic, microscopic geometry of interpenetrating melt and matrix. At this scale, incompressible Stokes flow is assumed to govern both phases, with appropriate interface conditions. Homogenization systematically leads to macroscopic equations for the melt and matrix velocities, as well as the bulk parameters, permeability and bulk viscosity, without requiring ad hoc closures for interphase forces. We show that homogenization can lead to a range of macroscopic models depending on the relative contrast in melt and solid properties such as viscosity or velocity. In particular, we identify a regime that is in good agreement with previous formulations, without including their attendant assumptions. Thus, this work serves as independent verification of these models. In addition, homogenization provides a consistent machinery for computing consistent macroscopic constitutive relations such as permeability and bulk viscosity that are consistent with a given microstructure. These relations are explored numerically in the companion paper.
A multiscale model of partial melts: 2. Numerical results
Authors: Simpson G. , Spiegelman M. , Weinstein M. I.
Published: April 2010

In the companion paper, equations for partially molten media were derived using two‐scale homogenization theory. This approach begins with a grain‐scale description and then coarsens it through multiple scale expansions into a macroscopic model. One advantage of homogenization is that effective material properties, such as permeability and the shear and bulk viscosity of the two‐phase medium, are characterized by cell problems, boundary value problems posed on a representative microstructural cell. The solutions of these problems can be averaged to obtain macroscopic parameters that are consistent with a given microstructure. This is particularly important for estimating the “compaction length” which depends on the product of permeability and bulk viscosity and is the intrinsic length scale for viscously deformable two‐phase flow. In this paper, we numerically solve ensembles of cell problems for several geometries. We begin with simple intersecting tubes, as this is a one parameter family of problems with well‐known results for permeability. Using the data, we estimate relationships between the porosity and all of the effective parameters by curve fitting. For the model of intersecting tubes, permeability scales as ϕn, n ∼ 2, as expected, and the bulk viscosity scales as ϕ−m, m ∼ 1, which has been speculated but never shown directly for deformable porous media. The second set of cell problems adds spherical inclusions where the tubes intersect. For these geometries, the permeability is controlled the pore throats and not by the total porosity, as expected. However, the bulk viscosity remains inversely proportional to the porosity, and we conjecture that this quantity is insensitive to the specific microstructure. The computational machinery developed can be applied to more general geometries, such as texturally equilibrated pore shapes. However, we suspect that the qualitative behavior of our simplified models persists in these more realistic structures. In particular, our hybrid numerical‐analytical model predicts that for purely mechanical coupling at the microscale, all homogenized models will have a compaction length that vanishes as porosity goes to zero. This has implications for numerical simulations, and it suggests that these models might not resist complete compaction.
A unified deep‐to‐shallow water wave‐breaking probability parameterization
Authors: Filipot Jean‐François , Ardhuin Fabrice , Babanin Alexander V.
Published: April 2010

Breaking probabilities and breaking wave height distributions (BWHDs) in deep, intermediate, and shallow water depth are compared, and a generic parameterization is proposed to represent the observed variability of breaking parameters as a function of the nondimensional water depth. In intermediate and deep water, where waves of different scales may have markedly different breaking probabilities, a BWHD as a function of wave frequency is proposed and validated with intermediate‐depth and deep water observational data. The current study focuses on waves with frequencies between 0.55 and 3.45 times the peak frequency fp. For the dominant frequency, the integration of the frequency‐dependent BWHD provides a breaking probability that reproduces the known threshold‐type behavior of the breaking probability for dominant waves. In shallow water, the present breaking statistics parameterization is consistent with other independent formulations validated by shallow water‐breaking observations.
Cloud cover increase with increasing aerosol absorptivity: A counterexample to the conventional semidirect aerosol effect
Authors: Perlwitz Jan , Miller Ron L.
Published: April 2010

We reexamine the aerosol semidirect effect using a general circulation model and four cases of the single‐scattering albedo of dust aerosols. Contrary to the expected decrease in low cloud cover due to heating by tropospheric aerosols, we find a significant increase with increasing absorptivity of soil dust particles in regions with high dust load, except during Northern Hemisphere winter. The strongest sensitivity of cloud cover to dust absorption is found over land during Northern Hemisphere summer. Here even medium and high cloud cover increase where the dust load is highest. The cloud cover change is directly linked to the change in relative humidity in the troposphere as a result of contrasting changes in specific humidity and temperature. More absorption by aerosols leads to larger diabatic heating and increased warming of the column, decreasing relative humidity. However, a corresponding increase in the specific humidity exceeds the temperature effect on relative humidity. The net effect is more low cloud cover with increasing aerosol absorption. The higher specific humidity where cloud cover strongly increases is attributed to an enhanced convergence of moisture driven by dust radiative heating. Although in some areas our model exhibits a reduction of low cloud cover due to aerosol heating consistent with the conventional description of the semidirect effect, we conclude that the link between aerosols and clouds is more varied, depending also on changes in the atmospheric circulation and the specific humidity induced by the aerosols. Other absorbing aerosols such as black carbon are expected to have a similar effect.
Land surface insulation response to snow depth variability
Authors: Ge Yan , Gong Gavin
Published: April 2010

The existing literature on heat diffusion through a snow‐covered land surface deals primarily with snow cover presence or duration; however, the insulation property of a snowpack can vary substantially owing to the changes in snow thickness. Using SNTHERM, a one‐dimensional snowpack energy and mass balance model, we have isolated the heat diffusion response to varying initial snow depths, including snow‐free conditions, and assessed the magnitude of associated temperature and insulative energy flux anomalies within the entire snowpack‐soil column system. A clear and substantial land surface insulative response to snow depth is identified over hourly, intraseasonal, and interannual time scales. The overall snow‐soil system warms with increasing snow depth, but the surface snow layer cools slightly, generating decreased ground heat flux and increased sensible heat flux responses. This land surface thermal response is attributable to the increased insulative capacity of deeper snowpacks, which makes the underlying soil less responsive to solar radiation and air temperature fluctuations, and facilitates sustained warming by the bottom soil layer boundary. Furthermore, the overall effect of increasing snow depth due to insulation is comparable in magnitude to the effect of snow presence versus snow absence due to albedo.
Satellite Observations From the International Polar Year
Authors: Jezek Kenneth , Drinkwater Mark
Published: April 2010

To realize the benefit of the growing number of international satellites to the scientific objectives of the 2007–2008 International Polar Year (IPY), the Global Interagency IPY Polar Snapshot Year (GIIPSY) was established in November 2005 to develop a consensus on polar science requirements and objectives for IPY that could best and perhaps only be met using the Earth‐observing satellites. Requirements focused on all aspects of the cryosphere and ranged from sea ice and ice sheets to permafrost and snow cover. Individual topics included how best to develop high‐resolution digital elevation models of outlet glaciers using stereo‐optical systems, measure ice sheet surface velocity using interferometric synthetic aperture radar (InSAR), and repeatedly measure sea ice motion using optical and microwave imaging instruments.

Because of this foresight, several IPY science objectives were well met using satellite observations, allowing a wealth of valuable data to be collected on cryospheric processes (Figure 1). Further, the framework for coordinating these remote sensing efforts serves as a valuable model for future coordinated efforts to monitor cryospheric dynamics.
Hubble 3D: A Science and Hollywood Collaboration Made (Nearly) in Heaven
Authors: Showstack Randy
Published: April 2010

Just 2 days after the 2010 Academy Awards® ceremony in early March bestowed Oscars® for motion picture achievements, NASA deputy administrator Lori Garver touted a new film about the Hubble Space Telescope, Hubble 3D, for best drama, special effects, screenplay, actors and actress, and director and producer. The 43‐minute IMAX and Warner Brothers Pictures production, which opened in theaters on 19 March, is an example of the ability of Hollywood and the science community to partner in providing a dynamic educational and entertaining product, according to a number of people associated with the film.

Sharing the red carpet at the Smithsonian National Air and Space Museum in Washington, D.C., with astronauts and others to mark the world premiere, Garver said the film shows the drama of the astronauts' efforts to repair the telescope while traveling 17,000 miles per hour and performing grueling space walks (see Figure 1). “We have literally opened our eyes on the universe through this telescope,” she said. “This is a taxpayer‐funded agency, and we are giving back to the public the very story that they paid for.”
Vithanage Receives 2009 Natural Hazards Focus Group Award for Graduate Research
Authors: Anonymous
Published: April 2010

Meththika Vithanage has been awarded the Natural Hazards Focus Group Award for Graduate Research, given annually to recent Ph.D. recipients for outstanding contributions to natural hazards research. Vithanage's thesis is entitled “Effect of tsunami on coastal aquifers: Field studies and tank experiments.” She was formally presented with the award at the Natural Hazards Focus Group reception during the 2009 AGU Fall Meeting, held 14–18 December in San Francisco, Calif.

Vithanage received her B.S. in natural resources from Sabaragamuwa University of Sri Lanka in 2002 and an M.S. in environmental science from the University of Peradeniya, Sri Lanka, in 2005. In 2009, she attained a Ph.D. in hydrogeology under the supervision of Karsten Jensen and Peter Engesgaard in the Department of Geology and Geography at University of Copenhagen, Denmark.
Monitoring the Antarctic Circumpolar Current in the Drake Passage: Oceanography in Drake Passage: Wherefrom, Whereto and What in Between? Liverpool, United Kingdom, 26–27 October 2009
Authors: Maqueda Miguel Angel Morales , Heywood Karen J. , Meredith Michael P.
Published: April 2010

The Antarctic Circumpolar Current (ACC), the world's largest oceanic fl ow (∼135 million cubic meters per second), is an important component of the ocean climate, as it connects the three major oceanic basins. Deep Atlantic water upwells between the ACC and Antarctica and returns to the Atlantic, thus contributing to the closure of the global overturning circulation. The Drake Passage, between the southern tip of South America and Antarctica, is the region where the ACC is most constricted by landmasses and, owing to its narrowness, is the most convenient place to monitor the ACC. The Drake Passage also has considerable oceanographic interest because it lies along the cold, returning route of the global overturning circulation and is a region of strong deepwater mixing.
Reconciling Differing Views of Tropical Pacific Climate Change
Authors: DiNezio Pedro , Clement Amy , Vecchi Gabriel
Published: April 2010

Recent analyses of global warming projections simulated with global climate models (GCMs) suggest that the tropical Pacific does not become El Niño‐ or La Niña‐like in response to increased greenhouse gases (GHGs). Rather, the physical mechanisms that drive tropical Pacific climate change depart substantially from the El Niño‐Southern Oscillation (ENSO) analogy often invoked for interpreting future climate changes [e.g., Knutson and Manabe, 1995; Meehl and Washington, 1996; Cane et al., 1997; Collins et al., 2005; Meehl et al., 2007; Lu et al., 2008; Cox et al., 2004] and past climate changes [e.g. Lea et al., 2001; Koutavas et al., 2002]. This presents an opportunity for reconciling theory, models, and observations.

An ENSO analogy typically is invoked for interpreting tropical Pacific climate change because if an external forcing introduces some east‐west asymmetry, this asymmetry can be amplified in the same way as interannual perturbations are, through the positive ocean‐atmosphere Bjerknes feedback. This then would lead to an altered mean state of the tropical Pacific resembling El Niño or La Niña [Dijkstra and Neelin, 1995]. For instance, the model projections used for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) anticipate tropical Pacific climate change in response to increased GHGs that has been described as El Niño—like [Meehl et al., 2007]. These models project robust enhanced equatorial warming [Liu et al., 2006; DiNezio et al., 2009] and a weakening of the overturning atmosphere circulation across the tropical Pacific, i.e., the Walker circulation [Vecchi and Soden, 2007], both of which occur during El Niño events. However, these experiments also show a shoaling and sharpening of the equatorial thermocline [Vecchi and Soden, 2007; DiNezio et al., 2009] (Figure 1a). This is in contrast to El Niño events, when the thermocline response is heavily dominated by a relaxed tilt (Figure 1b).
Volcanic vents found in deep Caribbean waters
Authors: Showstack Randy
Published: April 2010

Scientists surveying the Cayman Trough in the Caribbean Sea have discovered the world's deepest undersea volcanic vents, or “black smokers,” the National Oceanography Center (NOC) in Southampton, UK, announced on 11 April. The vents were found at a depth of 5000 meters, about 800 meters deeper than any previously discovered.

Jon Copley, a marine biologist at the University of Southampton's School of Ocean and Earth Science, said, “Seeing the world's deepest black‐smoker vents looming out of the darkness was awe‐inspiring.” Geochemist Doug Connelly of NOC, principal scientist of the expedition, noted, “We hope our discovery will yield new insights into biogeochemically important elements in one of the most extreme naturally occurring environments on our planet.” Researchers used an NOC‐developed Autosub6000 robot submarine, which was remotely controlled from the Royal Research Ship James Cook.
Updated International Geomagnetic Reference Field
Authors: Showstack Randy
Published: April 2010

The latest release of International Geomagnetic Reference Field (IGRF‐11) was published online at the end of 2009. IGRF is a standard reference model of Earth's internal magnetic field. The reference field is typically updated every 5 years by an international team of geomagnetic field modelers working under the auspices of the International Association of Geomagnetism and Aeronomy and in collaboration with institutions collecting and disseminating magnetic field measurements from satellites and a worldwide network of ground‐based observatories.

As with earlier versions of the reference field, IGRF‐11 provides a global picture of the past and present geomagnetic field as well as a linear prediction of field changes over the upcoming 5 years. IGRF is widely used in navigation and heading systems, geophysical surveying, and space weather modeling and prediction.
Recommendations for Interdisciplinary Study of Tipping Points in Natural and Social Systems
Authors: Jordan Teresa E. , Sala Osvaldo E. , Stafford Susan G. , Bubier Jill L. , Crittenden John C. , Cutter Susan L. , Kay Alan C. , Libecap Gary D. , Moore John C. , Rabalais Nancy N. , Shepherd J. Marshall , Travis Jospeh
Published: April 2010

In September 2009, the U.S. National Science Foundation's (NSF) Advisory Committee for Environmental Research and Education (AC‐ERE) released “Transitions and Tipping Points in Complex Environmental Systems,” a report that advocates sweeping change in the way environmental research and education are sponsored and conducted. The conviction of the committee that physical and life scientists, engineers, educators, and social scientists must work collaboratively to understand the dynamics of complex environmental systems should resonate with AGU's membership.

A major theme of the AC‐ERE report is that scientists need to understand environmental systems that, partly owing to human activity, may be approaching thresholds for irreversible change. This theme echoes sentiments expressed in the geosciences community, such as by Rockström et al. [2009], who estimate the magnitudes of thresholds for irreversible changes in nine key Earth subsystems and focus on how human activities have driven systems closer—or even past—some thresholds. The AC‐ERE report argues that understanding natural systems will require integrated research among geoscientists, social scientists, ecologists, and others.
2009 Mineral and Rock Physics Graduate Research Award to Yu and Austin
Authors: Anonymous
Published: April 2010

Yonggang Yu and Nicholas J. Austin have been awarded the Mineral and Rock Physics Graduate Research Award, given annually to one or more promising young scientists for outstanding contributions achieved during their Ph.D. research. Recipients of this award are engaged in experimental and/or theoretical studies of Earth and planetary materials with the purpose of unraveling the physics and chemistry that govern their origin and physical properties. Yu's thesis is entitled “Structure properties and phase transitions in earth minerals: A first principles study.” Austin's thesis is entitled “Grain size evolution and strain localization in deformed marbles.” They were both formally presented with the award at the Mineral and Rock Physics focus group reception during the 2009 AGU Fall Meeting, held 14–18 December in San Francisco, Calif.
Solute transporters and aquaporins are impaired in celiac disease
Authors: Laforenza Umberto , Miceli Emanuela , Gastaldi Giulia , Scaffino Manuela F. , Ventura Ulderico , Fontana Jacopo M. , Orsenigo Maria N. , Corazza Gino R.
Published: April 2010

Background information. Celiac disease is a chronic inflammatory disorder of the small bowel induced in genetically susceptible subjects by gluten ingestion. Diarrhoea, weight loss and malabsorption represent the major clinical presentation of the disease. Here we examined the possible alteration in the expression and localization of water channels [AQPs (aquaporins)] and some solute transporters in duodenal mucosa of celiac disease patients. Duodenal biopsies from untreated celiacs, treated celiacs, healthy controls and disease controls were considered in the present study. The expressions of some AQPs and transporter mRNAs in human duodenal biopsies were determined by semi‐quantitative RT—PCR (reverse transcription PCR) and real‐time RT—PCR. The localization of AQPs 3, 7 and 10 and of SGLT1 (Na+/glucose co‐transporter 1), PEPT1 (H+/oligopeptide transporter 1) and NHE3 (Na+/H+ exchanger 3) was evaluated by immunohistochemistry.

Results. AQPs 3, 7, 10 and 11, SGLT, PEPT and NHE, CFTR (cystic fibrosis transmembrane conductance regulator) and NKCC (Na‐K‐2Cl co‐transporter) mRNAs were expressed in duodenal biopsies of healthy controls, treated celiac patients and disease controls. The expression of transcripts was virtually absent in duodenal biopsies of untreated celiac disease patients except for CFTR and NKCC. In healthy controls, immunohistochemistry revealed a labelling in the apical membrane of surface epithelial cells of the duodenum. The immunolabelling was heavily reduced or absent in untreated celiac patients, while it was normal in patients consuming a gluten‐free diet for at least 12 months.

Conclusions. Our results indicate that the main routes for water and solute absorption are deficient in celiac disease and may play a role in the onset of malabsorption symptoms.
Two-step and one-step secretion mechanisms in Gram-negative bacteria: contrasting the type IV secretion system and the chaperone-usher pathway of pilus biogenesis
Authors: Rêgo Ana Toste , Chandran Vidya , Waksman Gabriel
Published: April 2010

Gram-negative bacteria have evolved diverse secretion systems/machineries to translocate substrates across the cell envelope. These various machineries fulfil a wide variety of functions but are also essential for pathogenic bacteria to infect human or plant cells. Secretion systems, of which there are seven, utilize one of two secretion mechanisms: (i) the one-step mechanism, whereby substrates are translocated directly from the bacterial cytoplasm to the extracellular medium or into the eukaryotic target cell; (ii) the two-step mechanism, whereby substrates are first translocated across the bacterial inner membrane; once in the periplasm, substrates are targeted to one of the secretion systems that mediate transport across the outer membrane and released outside the bacterial cell. The present review provides an example for each of these two classes of secretion systems and contrasts the various solutions evolved to secrete substrates.
Structure and function of the GINS complex, a key component of the eukaryotic replisome
Authors: MacNeill Stuart A.
Published: April 2010

High-fidelity chromosomal DNA replication is fundamental to all forms of cellular life and requires the complex interplay of a wide variety of essential and non-essential protein factors in a spatially and temporally co-ordinated manner. In eukaryotes, the GINS complex (from the Japanese go-ichi-ni-san meaning 5-1-2-3, after the four related subunits of the complex Sld5, Psf1, Psf2 and Psf3) was recently identified as a novel factor essential for both the initiation and elongation stages of the replication process. Biochemical analysis has placed GINS at the heart of the eukaryotic replication apparatus as a component of the CMG [Cdc45–MCM (minichromosome maintenance) helicase–GINS] complex that most likely serves as the replicative helicase, unwinding duplex DNA ahead of the moving replication fork. GINS homologues are found in the archaea and have been shown to interact directly with the MCM helicase and with primase, suggesting a central role for the complex in archaeal chromosome replication also. The present review summarizes current knowledge of the structure, function and evolution of the GINS complex in eukaryotes and archaea, discusses possible functions of the GINS complex and highlights recent results that point to possible regulation of GINS function in response to DNA damage.
Identification of the structural motif responsible for trimeric assembly of the C-terminal regulatory domains of polycystin channels PKD2L1 and PKD2
Authors: Molland Katrina L. , Narayanan Anoop , Burgner John W. , Yernool Dinesh A.
Published: April 2010

Polycystin 2-type cation channels PKD2 and PKD2L1 interact with polycystin 1-type proteins PKD1 and PKD1L3 respectively, to form receptor–cation-channel complexes. The PKD2L1–PKD1L3 complex perceives sour taste, whereas disruption of the PKD2–PKD1 complex, responsible for mechanosensation, leads to development of ADPKD (autosomal-dominant polycystic kidney disease). Besides modulating channel activity and related signalling events, the CRDs (C-terminal regulatory domains) of PKD2 and PKD2L1 play a central role in channel oligomerization. The present study investigates the aggregation state of purified full-length PKD2L1-CRD as well as truncations of CRDs from PKD2 channels. Far- and near-UV CD spectroscopy show that the full-length PKD2L1 CRD (PKD2L1-198) and the truncated PKD2 CRD (PKD2-244) are α-helical with no β-sheet, the α-helix content agrees with sequence-based predictions, and some of its aromatic residues are in an asymmetric environment created at least by partially structured regions. Additionally, the CRD truncations exhibit an expected biochemical function by binding Ca2+ in a physiologically relevant range with Kd values of 2.8 μM for PKD2-244 and 0.51 μM for PKD2L1-198. Complimentary biophysical and biochemical techniques establish that truncations of the PKD2 and PKD2L1 CRDs are elongated molecules that assemble as trimers, and the trimeric aggregation state is independent of Ca2+ binding. Finally, we show that a common coiled-coil motif is sufficient and necessary to drive oligomerization of the PKD2 and PKD2L1 CRD truncations under study. Despite the moderate sequence identity (39%) between CRDs of PKD2 and PKD2L1, they both form trimers, implying that trimeric organization of CRDs may be true of all polycystin channels.
The reconstituted Escherichia coli MsbA protein displays lipid flippase activity
Authors: Eckford Paul D. W. , Sharom Frances J.
Published: April 2010

The MsbA protein is an essential ABC (ATP-binding-cassette) superfamily member in Gram-negative bacteria. This 65 kDa membrane protein is thought to function as a homodimeric ATP-dependent lipid translocase or flippase that transports lipid A from the inner to the outer leaflet of the cytoplasmic membrane. We have previously shown that purified MsbA from Escherichia coli displays high ATPase activity, and binds to lipids and lipid-like molecules, including lipid A, with affinity in the low micromolar range. Bacterial membrane vesicles isolated from E. coli overexpressing His6-tagged MsbA displayed ATP-dependent translocation of several fluorescently NBD (7-nitrobenz-2-oxa-1,3-diazole)-labelled phospholipid species. Purified MsbA was reconstituted into proteoliposomes of E. coli lipid and its ability to translocate NBD-labelled lipid derivatives was characterized. In this system, the protein displayed maximal lipid flippase activity of 7.7 nmol of lipid translocated per mg of protein over a 20 min period for an acyl chain-labelled PE (phosphatidylethanolamine) derivative. The protein showed the highest rates of flippase activity when reconstituted into an E. coli lipid mixture. Substantial flippase activity was also observed for a variety of other NBD-labelled phospholipids and glycolipids, including molecules labelled on either the headgroup or the acyl chain. Lipid flippase activity required ATP hydrolysis, and was dependent on the concentration of ATP and NBD–lipid. Translocation of NBD–PE was inhibited by the presence of the putative physiological substrate lipid A. The present paper represents the first report of a direct measurement of the lipid flippase activity of purified MsbA in a reconstituted system.
SUMO modification regulates the transcriptional activity of XBP1
Authors: Chen Hui , Qi Ling
Published: April 2010

The UPR (unfolded protein response), a cellular defence mechanism against misfolded protein accumulation in the ER (endoplasmic reticulum), is associated with many human diseases such as aging, cancer and diabetes. XBP1 (X-box-binding protein 1), a key transcription factor of the UPR, is critical in maintaining ER homoeostasis. Nevertheless, the mechanism by which XBP1 transcriptional activity is regulated remains unexplored. In the present study we show that XBP1s, the active spliced form of XBP1 protein, is SUMOylated, mainly by PIAS2 [protein inhibitor of activated STAT (signal transducer and activator of transcription) 2] at two lysine residues located in the C-terminal transactivation domain. Ablation of these SUMOylation events significantly enhances the transcriptional activity of XBP1s towards UPR target genes. Thus our results reveal an unexpected role for SUMO (small ubiquitin-related modifier) in the regulation of UPR activation and ER homoeostasis.
Transferrin-iron routing to the cytosol and mitochondria as studied by live and real-time fluorescence
Authors: Shvartsman Maya , Fibach Eitan , Cabantchik Z. Ioav
Published: April 2010

In the present study we analysed the mechanism of intracellular routing of iron acquired by erythroid cells via receptor-mediated endocytosis of Tf-Fe [Tf (transferrin)-iron]. Using real-time fluorimetry and flow cytometry, in conjunction with targeted fluorescent metal sensors, we monitored concurrently the cytosolic and mitochondrial changes in labile iron evoked by endocytosed Tf-Fe. In K562 human erythroleukaemia cells, most of the Tf-Fe was found to be delivered to the cytosolic labile iron pool by a saturable mechanism [60–120 nM Km (app)] that was quantitatively dependent on: Tf receptor levels, endosomal acidification/reduction for dislodging iron from Tf and ensuing translocation of labile iron into the cytosolic compartment. The parallel ingress of iron to mitochondria was also saturable, but with a relatively lower Km (app) (26–42 nM) and a lower maximal ingress per cell than into the cytosol. The ingress of iron into the mitochondrial labile iron pool was blocked by cytosol-targeted iron chelators, implying that a substantial fraction of Tf-Fe delivered to these organelles passes through the cytosol in non-occluded forms that remain accessible to high-affinity ligands. The present paper is the first report describing intracellular iron routing measured in intact cells in real-time and in quantitative terms, opening the road for also exploring the process in mixed-cell populations of erythroid origin.
Characterization of novel VEGF (vascular endothelial growth factor)-C splicing isoforms from mouse
Authors: Wang Zhen-Guo , Puri Tipu S. , Quigg Richard J.
Published: April 2010

VEGF (vascular endothelial growth factor)-C is a major growth factor implicated in various physiological processes, such as angiogenesis and lymphangiogenesis. In the present paper, we report the identification of three short VEGF-C splicing isoforms (VEGF-C62, VEGF-C129 and VEGF-C184) from immortalized mouse kidney PTECs (proximal tubular epithelial cells). Semi-quantitative RT (reverse transcription)–PCR analysis showed these isoforms were universally expressed to varying degrees in different tissues with high expression levels in the kidney. In immortalized PTECs and podocytes, VEGF-C62 can activate phosphorylation of FAK (focal adhesion kinase) and promote cell adhesion to substratum. Cell survival was also increased by VEGF-C62 treatment in the absence of serum. VEGF-C62 can also reduce cell proliferation in PTECs and podocytes. Nucleolin was one of the proteins that associated with VEGF-C62 in pull-down assays using GST (glutathione transferase) fusion proteins as bait, indicating different protein binding requirements for VEGF-C62 compared with VEGF-C. In conclusion, these newly identified VEGF-C isoforms represent a new class of proteins, which are potentially involved in epithelial cell adhesion and proliferation through novel receptor pathways.