bluuebunny/crossref_metadata_2025 huggingface dataset:
Exoplanets – search methods, discoveries, and prospects for astrobiology
Authors: Jones B.W.
Published: December 2008

Whereas the Solar System has Mars and Europa as the best candidates for finding fossil/extant life as we know it – based on complex carbon compounds and liquid water – the 263 (non-pulsar) planetary systems around other stars as known at 15 September 2008 could between them possess many more planets where life might exist. Moreover, the number of these exoplanetary systems is growing steadily, and with this growth there is an increase in the number of planets that could bear carbon–liquid water life. In this brief review the main methods by which exoplanets are being discovered are outlined, and then the discoveries that have so far been made are presented. This is followed by an account of likely future discoveries. Habitability is then discussed, and an outline presented of how a planet could be studied from afar to determine whether it is habitable, and whether it is indeed inhabited. This review is aimed at the astrobiology community, which spans many disciplines, few of which involve exoplanets. It is therefore at a basic level and concentrates on the major topics.
Bacteria variabilities in a Tibetan ice core and their relations with climate change
Authors: Yao Tandong , Liu Yongqin , Kang Shichang , Jiao Nianzhi , Zeng Yonghui , Liu Xiaobo , Zhang Yongjun
Published: December 2008

Bacterial abundances in ice cores vary in response to climatic conditions. This paper presents annual bacterial abundances measured in ice deposited over the past 70 years and trapped within a core retrieved from Mount Geladaindong, on the central Tibetan Plateau. The bacterial abundance was lowest in 1938 and highest in 1997. Analyses of correlations between bacterial abundance and δ18O and Ca2+ concentrations indicate that bacterial abundance correlates positively with both temperature and amount of dust transported onto the glacier. These correlations imply that both higher temperatures and more frequent dust deposition influence bacterial abundance in the Geladaindong ice core. Bacterial genetic diversity also changes seasonally, and the diversity during the monsoon season appears much higher than during the nonmonsoon season. Bacterial sequences representing the monsoon season were related to bacteria originating from various environmental conditions while these, representing the nonmonsoon season, were typically related to microorganisms coming from cold environments and soils.
Inferring D region parameters using improved incoherent scatter radar techniques at Arecibo
Authors: Raizada Shikha , Sulzer Michael P. , Tepley Craig A. , Gonzalez Sixto A. , Nicolls Michael J.
Published: December 2008

With the increased sensitivity and bandwidth, Arecibo 430 MHz incoherent scatter radar was run on 23 July 2006 using two radar modes with a focus on measuring D region parameters. One mode measured the ion line spectra over D region altitudes; the other mode was used as a new way to calibrate the electron densities in the D region and also to correct the ion line spectra. The ion line primarily provided a power profile connecting the D region to altitudes where the plasma line is useful. The plasma line provided the absolute electron density, used in the lower altitudes for calibration, and at F region altitudes for determining the baseline level in the D region spectra due to the folding‐in of F region scattered power. It is found that the electron line contribution is about 1–3 times the ion line between 60–75 km altitude ranges. Electron concentration was found to be in the range of a few hundred to 5000 cm−3 in the 65–90 km altitude range. The new technique agrees well with the previous measurements. The D region spectral widths were used to calculate the ratio of negative ion to electron concentration (λ). Between 0900 and 1100 LT, a 4 km thick layer of negative ions was observed with λ ∼ 1.6 ± 0.3 around 73–77 km. In the altitude range of 81–91 km, we inferred temperatures ∼ 195–215 K using ion‐neutral collision frequencies determined from the spectral widths.
Seismology Across the Northeastern Edge of the Tibetan Plateau
Authors: Zhao W. , Brown L. , Wu Z. , Klemperer S. L. , Shi D. , Mechie J. , Su H. , Tilmann F. , Karplus M. S. , Makovsky Y.
Published: December 2008

On 12 May, a great earthquake (Ms=8.0) on the Longmenshan thrust fault rumbled through Chinas Sichuan province, killing more than 69,000 people and injuring 374,000. The Longmenshan thrust is part of the eastern border of the Tibetan Plateau, but it is not the plateaus only restless margin. An even larger earthquake (Ms=8.1) on the Kunlun fault shook northeastern Tibet in 2001, fortunately in a sparsely populated area. These massive quakes underscore the importance of understanding the tectonic response of Asia to collision by India.

The International Deep Profiling of Tibet and the Himalaya (INDEPTH) program explores the dynamics of the India‐Asia collision. Though many past geophysical studies have focused on the Himalayas and the southern Tibetan Plateau, the INDEPTH IV project examines the deep structure of the northeastern margin of the Tibetan Plateau.
The 2008 AGU Fall Meeting
Authors: Johnson Catherine
Published: December 2008

The 2008 AGU Fall Meeting, to be held 15–19 December in San Francisco, is likely to be the largest AGU meeting to date. More than 15,800 presentations are scheduled, and more than 11,000 participants registered prior to the early‐bird deadline of 14 November.

This year, all oral sessions and the exhibit hall will be in Moscone West, and all poster sessions will be in Moscone North. (The American Society for Cell Biology will be holding its annual meeting in Moscone South.) Meeting attendees will receive general information including an author index, maps, and a list of sessions by discipline, cosponsors, day, time, and location.

To reduce the environmental impact of the meeting, hard‐copy programs will no longer contain detailed session information—this is available on the Fall Meeting Web site, and terminals will be available to look up the meeting schedule on‐site. To increase accessibility of meeting highlights to those who cannot attend, approximately one Union session per day will be available as a live webcast (see the Fall Meeting Web site for details). Named lectures at the meeting will also be recorded; webcasts of these lectures will be posted after the talk.
Examining Arctic Ice Shelves Prior to the 2008 Breakup
Authors: Mueller Derek R. , Copland Luke , Hamilton Andrew , Stern Doug
Published: December 2008

The last time researchers stood on the surface of the Serson Ice Shelf, at the northern end of Ellesmere Island, Canada, it was a chilly 26°C April day in 2008. On a relatively warm 8°C day 3 months later, the ice shelf began to break apart and within 3 weeks lost 122 square kilometers (60%) of its area. This past summer, Ellesmere's 50‐square‐kilometer Markham Ice Shelf also broke away, and there was major fracturing throughout the eastern half and well into the western half of the Ward Hunt Ice Shelf, which is the largest remaining ice shelf in the Northern Hemisphere.
Boron and chlorine contents of upper oceanic crust: Basement samples from IODP Hole 1256D
Authors: Sano Takashi , Miyoshi Masaya , Ingle Stephanie , Banerjee Neil R. , Ishimoto Mitsunori , Fukuoka Takaaki
Published: December 2008

Boron, Cl, Ti, K, Sm, and Gd concentrations of oceanic crust samples were determined by prompt gamma neutron activation analysis. The samples include 63 basalts and 5 gabbros obtained at various depths (369–1503 m below seafloor) from Hole 1256D during Ocean Drilling Program Leg 206 and Integrated Ocean Drilling Program Expedition 309 and 312. The results show stepwise downhole variations, B content and B/K decrease, and Cl content and Cl/K increase with increasing depth. High B content (>1.5 ppm) in shallower rocks (extrusive lavas) is probably achieved by low‐temperature seawater alteration, and high Cl contents (up to 1400 ppm) in the deeper rocks (plutonic section) would show result of high‐temperature hydrothermal alteration. Average B and Cl values for the upper oceanic crust in Hole 1256D are 1.5 ppm and 334 ppm, respectively.
Semiannual oscillations in the atmosphere of Mars
Authors: Kuroda Takeshi , Medvedev Alexander S. , Hartogh Paul , Takahashi Masaaki
Published: December 2008

We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day‐ and night‐time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving mechanisms of the SAO between Mars and Earth. On Mars, unlike on Earth, equatorial Kelvin waves supply only small retrograde torque to the mean circulation. Instead, thermal tides and quasi‐stationary planetary waves induced by Martian topography contribute strongly to the prograde (super‐rotation) acceleration. The existence of the SAO on Mars suggests that this phenomenon is not a result of the unique terrestrial environment, but a more general consequence of wave‐mean flow interactions in atmospheres of fast‐rotating planets.
Determination of the substorm initiation region from a major conjunction interval of THEMIS satellites
Authors: Lui A. T. Y. , Angelopoulos V. , LeContel O. , Frey H. , Donovan E. , Sibeck D. G. , Liu W. , Auster H. U. , Larson D. , Li X. , Nosé M. , Fillingim M. O.
Published: December 2008

We investigate in detail the time history of substorm disturbances in the magnetotail observed during a major tail conjunction of Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites on 29 January 2008, 0700–0900 UT. During this interval, all THEMIS satellites were closely aligned along the tail axis near midnight and were bracketed in local time by GOES 11 and 12. The radial distance covered ranges from the geosynchronous altitude to ∼30 RE in the tail. This interval consists of three activations detected by the THEMIS satellites with good ground all‐sky‐camera observations of auroral activity. The first activation is a small substorm with spatially limited disturbance in the tail. The onset arc was equatorward of an undisturbed arc. The second activation is a moderate size substorm with the onset arc also being equatorward of an undisturbed arc. The third activation is an intensification of the substorm with its onset indicated by the second activation. The active auroral arc for this intensification was near the poleward boundary of the auroral oval. Analysis of these observations indicates that the first activation is a small substorm initiated in the near‐Earth plasma sheet and does not involve magnetic reconnection of open magnetic field lines. Magnetic reconnection on closed field lines can be ruled out for this substorm because it cannot generate the observed high‐speed plasma flow. The second and third activations are part of a moderate size substorm initiated also in the near‐Earth plasma sheet, with a subsequent substorm intensification involving activity initiated tailward of ∼30 RE. Overall, the time history of substorm activity for these two substorms is consistent with the near‐Earth initiation model.
Radiative effect of ozone change on stratosphere‐troposphere exchange
Authors: Xie Fei , Tian Wenshou , Chipperfield Martyn P.
Published: December 2008

The potential radiative impact of ozone changes on stratosphere‐troposphere exchange (STE) is investigated by a series of climate model simulations. The impact of an arbitrary 15% O3 change on temperature, stratospheric water vapor, and cross‐tropopause mass flux are compared to the corresponding effects from a doubling of atmospheric CO2. Our analysis shows that a 15% global O3 decrease can cause a maximum cooling of 2.4 K in the stratosphere and ∼7.2% increase in the tropical upwelling. This cooling also results in a higher tropical tropopause and lower tropopause temperatures, and hence less stratospheric water vapor and smaller amplitude of the so‐called tape recorder signal. A global 15% O3 increase gives rise to ∼2.1 K stratospheric warming and ∼4% decrease in the tropical upwelling. This O3 increase results in more water vapor entering the stratosphere owing to a lower tropopause and higher tropopause temperatures. The effect of a ±15% change in O3 below 100 hPa is relatively small. However, the effect of a 15% O3 increase between 200 and 70 hPa is similar to that of a 15% O3 increase through the whole domain, suggesting that ozone increases in the UTLS dominate the impacts on temperature and tropical upwelling. Sea surface temperature (SST) changes associated with increasing atmospheric greenhouse gases (GHG) have a profound impact on the STE. Without corresponding SST changes, the radiative effects of the CO2 doubling on the STE is less significant than a global 15% O3 increase. When the SST changes are considered in the doubled CO2 experiment, the tropical upwelling is significantly increased (by 20.4%) with a much higher, but warmer, tropopause.
Changes in mixing ratio and isotopic composition of CO2 in urban air from the Los Angeles basin, California, between 1972 and 2003
Authors: Newman Sally , Xu Xiaomei , Affek Hagit P. , Stolper Edward , Epstein Samuel
Published: December 2008

Atmospheric CO2 mixing ratios and C and O isotopic compositions are reported for the Los Angeles basin in southern California, a region renowned for its air pollution. Air samples collected midday on the Caltech campus in Pasadena, California, contained ∼30 ppm more CO2 in 1998–2003 than in 1972–1973 (averaging 397 ppm in 1998–2003 and 366 ppm in 1972–1973) compared to a 47 ppm change in background air CO2, yet the ranges of the carbon and oxygen isotopic compositions remained essentially constant. Because the 1998–2003 data show a significant progression through time, analysis was done on data from 2002 to 2003 complete calendar years (CO2 mixing ratios increased 41 ppm between 1972 and 1973 and 2002–2003). Both 1972–1973 and 2002–2003 data sets display significant correlation between δ13C and 1/[CO2] with local CO2 source end‐member δ13C values of −30.9 ± 0.5‰ for 1972–1973 and −29.9 ± 0.2‰ for 2002–2003 (1σ errors). Mass balance calculations explain that this apparently coincidental similarity reflects a change in the relative proportion of natural gas and petroleum products burned in the region combined with a change in the origin, and thus isotopic composition, of the petroleum burned. The δ13C of the average CO2 inventory in Pasadena can be explained by local addition to background air of 38 ± 4 ppm CO2 in 1972–1973 and 29 ± 3 ppm in 2002–2003 from anthropogenic sources, in seeming contradiction to the known increase in CO2 emissions between these two time periods.
Modeling optical properties of mineral dust over the Indian Desert
Authors: Mishra S. K. , Tripathi S. N.
Published: December 2008

The direct radiative forcing (DRF) of dust particles is most uncertain among all the major aerosol species because of the large regional variation in their shapes and composition. The Indian Desert is known to be a source of natural mineral dust of nonspherical shapes. Particle shape and exact mineralogical information are essential for modeling dust optical properties as the latter governs their refractive indices. The realistic dust shapes, namely, sphere, spheroid, Chebyshev, and cylinder, based on Scanning Electron Microscope (SEM) images, have been used to model the mineral dust optics of the Indian Desert using the T‐matrix method. The particle radius from 0.1 to 5.0 μm has been considered at wavelengths ranging from ultraviolet to near infrared (0.38–1.2 μm). Using Bruggman's effective medium mixing rule, the refractive index of composite dust particle has been calculated, accounting for both nonmetallic and metallic component (as hematite). Our calculations show that increasing the hematite percentage from 0% to 10% results in reduction of 0.477 and 0.013 in single scattering albedo (SSA) for cylindrical particle of radius 1 μm at 0.38 and 1.02 μm wavelengths, respectively, while the same for volume equivalent spherical particle were 0.484 and 0.022, respectively. The scattering signature of sharp‐edged cylindrical particle showed the largest deviation to sphere compared with that of other relatively smooth particles (spheroid and Chebyshev). Changes in dust optical properties because of nonsphericity and varying hematite percentage were estimated for two cases: background dust and dust storm at visible wavelength. The change in SSA between the above two cases was insignificant for particles of radii <0.4 μm for each hematite percentage considered. On the other hand, for particles of size range 0.4–1 μm, the change in SSA increases with increasing hematite percentage. A 6% increase in hematite leads to an SSA reduction of more than 0.2 for particle radius of 1 μm for both background dust and dust storm cases. Optical properties of polydisperse dust distribution at visible wavelength suggest the likely hematite percentage as 0%–4% in the Indian mineral desert dust. The effect of hematite variation on SSA is found to be stronger than particle nonsphericity. The present work will lead to a better estimation of the radiative forcing imposed by dusts as well as their satellite retrieval over the Indian Desert region.
Seasonal variations of CO2 near the tropopause observed by commercial aircraft
Authors: Sawa Yousuke , Machida Toshinobu , Matsueda Hidekazu
Published: December 2008

We present variations of CO2 in the tropopause region obtained by frequent in situ measurements aboard commercial aircraft. The data were obtained from a total of 373 flights between Japan and Europe during the period November 2005 to September 2007. The local phase and amplitude of the CO2 seasonal cycle varied with distance from the tropopause. In the upper troposphere and in the region just above the dynamical tropopause, a strong seasonal cycle with a springtime maximum and a relatively sharp minimum in July was observed. In the region bounded by potential temperatures 10 K to 30 K above the extratropical tropopause, no significant seasonal cycles were found. In the region greater than 30 K from the tropopause (i.e., at higher altitudes), sharp CO2 increases in summer followed by gradual decreases were found, resulting in a slightly increasing seasonal cycle amplitude with distance from the tropopause. The observed CO2 distributions also showed that CO2 isopleths followed the tropopause during the winter and spring, whereas in the summer they tracked potential temperature surfaces crossing the tropopause. The observed seasonal variation in CO2 suggests that the lowermost stratospheric region is influenced by a combination of (1) fast meridional transport of high CO2 from the tropical troposphere in the summer, (2) active subsidence of low CO2 from higher altitudes in the spring, and (3) relatively weak vertical mixing near the tropopause.
Elevated stream inorganic nitrogen impacts on a dominant riparian tree species: Results from an experimental riparian stream system
Authors: Hultine K. R. , Jackson T. L. , Burtch K. G. , Schaeffer S. M. , Ehleringer J. R.
Published: December 2008

The release of inorganic nitrogen from intensive agricultural practices and urbanization has resulted in significant alterations of the aquatic nitrogen cycle in riparian ecosystems. Nevertheless, impacts of stream nitrogen inputs on the terrestrial nitrogen cycle and the water and carbon cycles are unclear. Information on terrestrial ecosystem responses to stream N loading is largely absent in part because of the difficulty in controlling for temporal and spatial variation in streamflow, geomorphology, climate, and vegetation. To address these issues, we constructed a dual‐plot artificial stream riparian system within a 10‐year‐old plantation of a dominant riparian tree species, box elder (Acer negundo). The dual‐plot design allowed for different concentrations of stream inorganic nitrogen between plots while controlling for ecohydrologic and geohydrologic variability. The system was used to investigate elevated inorganic stream nitrogen impacts on water use patterns, above‐ground productivity, and leaf chemistry of streamside box elder trees over two consecutive growing seasons (2006 and 2007). One plot received inorganic soluble fertilizer that brought the NO3 concentration of stream water from 5 μmol l−1 to about 100 μmol l−1, while the second plot received no additional nitrogen. Relative stem sap flux density (Js) did not vary between plots until near the conclusion of the 2006 growing season, when trees in the fertilized plot showed a steep upswing in Js relative to trees in the control plot. Sap flux in 2007 increased consistently by 0.4% day−1 in the fertilized plot relative to the control plot over a 75‐day period, before leveling off near the conclusion of the growing season. At the onset of the experiment, leaf nitrogen per unit mass and leaf nitrogen per unit area were significantly higher in the control plot, and leaf C:N ratios were lower. In 2007, however, differences in leaf chemistry disappeared, suggesting that leaf nitrogen increased in the fertilized trees relative to the control trees. Stem diameter growth in 2007 was 15% greater in the fertilized trees, although there were no differences in either canopy radial or canopy height growth throughout the experiment. Results from this investigation suggest that increases in stream inorganic nitrogen affect water use, litter quality, and productivity of dominant riparian vegetation. These effects may have important feedbacks on several ecohydrological processes.
Gastric Electrical Stimulation for Obesity: The Need for a New Device Using Wider Pulses
Authors: Zhang Jing , Tang Ming , Chen Jiande D.Z.
Published: December 2008

Gastric electrical stimulation (GES) has been proposed as a therapeutic option for obesity. However, its clinical efficacy is not proven, and its mechanisms remain largely unknown. To compare the peripheral and central neural and behavioral effects in rats of GES with a pulse width currently used in clinical trials (GES‐A: 6 mA, 0.3 ms, 40 Hz, 2 s on, 3 s off) and GES with a wider pulse (GES‐B: same as GES‐A, except that the pulse width is 3 ms). Experiment 1: assessing gastric volume changes as a result of GES. Experiment 2: recording the extracellular potentials of a single neuron in the paraventricular nucleus (PVN) with GES. Experiment 3: determining the effects of GES on oxytocin‐immunoreactive (OT‐IR) neuron expression in the hypothalamus. Experiment 4: determining the effects of GES on food intake and body weight. GES‐B, but not GES‐A, significantly increased gastric volume. GES‐B activated a higher percentage of gastric distention‐responsive neurons in the PVN (93% vs. 81%, P = 0.021) and elicited more intensive neuronal responses than GES‐A. The number of OT‐IR neurons was significantly increased in the PVN and supraoptic nucleus with both methods of GES compared with control groups. The increase in OT‐IR neurons in the PVN was higher with GES‐B than with GES‐A. A 1‐week GES treatment significantly reduced daily food intake and body weight. GES‐B was more potent than GES‐A in producing weight loss (P < 0.001). The effects of GES depend on the stimulation pulse width. GES with a wider pulse is more effective both peripherally and centrally and more potent in reducing body weight in rats.
Association Analyses Between Type 2 Diabetes Genes and Obesity Traits in Pigs
Authors: Du Zhi‐Qiang , Fan Bin , Zhao Xia , Amoako Randy , Rothschild Max F.
Published: December 2008

To investigate candidate genes involved in human type 2 diabetes (T2D) for obesity‐related phenotypes in pigs. Statistical association analyses of genes with fat deposition were realized in a pig reference family constructed by two breeds, Berkshire and Yorkshire. Extensive sequencing was then attempted to discover the causative polymorphism. Genes implied in human T2D development, TCF7L2, WFS1, FTO, SLC30A8, and GCKR, were mapped on Sus scrofa chromosomes 14, 8, 6, 4, and 3, respectively. Only TCF7L2 was significantly associated with five fat traits in pigs. Further investigation demonstrated that one haplotype (HapB), but not the HapA (homologous to the region for human T2D susceptibility where single‐nucleotide polymorphism (SNP) rs7903146 is located), is significantly associated with the fat‐related traits. In HapB, two SNPs in TCF7L2 exon 8 and intron 10 are significantly associated with five fat traits, and may be in linkage disequilibrium with the causative variant with additive effects on all four backfat traits, and the total lipid percentage. Pigs of genotype TT for the SNP in exon 8 have only one transcript isoform (the one without exon 4), and lower backfat depth. Candidate gene analyses could provide novel ideas about how these genes function in T2D susceptibility in human, and support that the pig can be a suitable model for human obesity and T2D research. Further replication of this research in other pig populations should be considered, so that the possibility of utilizing these genetic markers in pig breeding or in animal model research can be explored.
A fragment of the envelope protein from dengue‐1 virus, fused in two different sites of the meningococcal P64k protein carrier, induces a functional immune response in mice
Authors: Hermida Lisset , Rodríguez Rayner , Lazo Laura , Bernardo Lídice , Silva Ricardo , Zulueta Aída , López Carlos , Martín Jorge , Valdés Iris , Del Rosario Delfina , Guillén Gerardo , Guzmán María G.
Published: December 2008

Previously we have reported the capacity of the fusion protein PD3, composed of the P64k protein and the envelope (E) fragment from amino acids (aa) 286–426 of dengue‐2 virus (DEN‐2), to induce a functional immune response in mice against the homologous virus. In that case, the E fragment was inserted within the lipoyl‐binding domain of the meningococcal P64k protein. In the present study, to test the functionality of the same E region from dengue‐1 (DEN‐1), a similar construct was made. Furthermore, another alternative of fusion protein was also constructed where the same E fragment from DEN‐1 was fused to the C‐terminus of the P64k protein. The recombinant proteins obtained (PD11 and PD10) were semi‐purified and analysed for their antigenicity, immunogenicity and the ability to protect mice against lethal challenge. Both molecules exhibited the same recognition patterns against anti‐DEN‐1 polyclonal antibodies. In addition, when administered to mice, they elicited high levels of neutralizing antibodies and induced significant protection against lethal challenge with DEN‐1 after intracerebral inoculation. These results reveal the availability of two sites within the P64k for the further insertion of DEN fragments, enabling a construct carrying two fragments from heterologous serotypes within the same molecule of this protein carrier.
Determination of gibberellins in fermentation broth produced by Fusarium verticilliodes MTCC 156 by high‐performance liquid chromatography tandem mass spectrometry
Authors: Sharma Rohit , Iyer Jitesh P. , Chakraborti Asit K. , Banerjee Uttam Chand
Published: December 2008

A method for the detection of gibberellins produced by Fusarium verticilliodes is described using HPLCMS/MS (HPLC tandem MS). A Hypersil (5 μm) octadecylsilane column with methanol/water as eluent in the ratio 3:1 at a flow rate of 0.5 ml/min was used. In the HPLCMS, GA3 (gibberellic acid; m/z 346.3) eluted at retention time tr=3.08 min, with the corresponding mass chromatogram having peaks at m/z 346.7 and 328.8 corresponding to the M+ and M+−H2O ions respectively. The ethyl acetate extract from the broth, subjected to HPLCMS analysis under similar conditions, showed a constituent with tr=2.13 min, the mass chromatogram of which exhibited peaks at m/z 348.9 and 331.9 corresponding to the MH+ and MH+−H2O ions respectively. Comparison of the MS and MS/MS results (direct infusion) of an authentic sample of GA3 and the ethyl acetate extract from the broth revealed the formation of reduced GA3 in the broth. The present study, utilizing HPLCMS/MS, describes an improved methodology for the unambiguous determination and estimation of gibberellins from fermentation broth.
Xenopus death‐domain‐containing proteins FADD and RIP1 synergistically activate JNK and NF‐κB
Authors: Ishizawa Yo‐hei , Tamura Kei , Yamaguchi Tadayuki , Matsumoto Ken , Komiyama Masaru , Takamatsu Nobuhiko , Shiba Tadayoshi , Ito Michihiko
Published: December 2008

Background information. Death receptors (DRs) induce intracellular signalling upon engagement of their cognate ligands, leading to apoptosis, cell survival or pro‐inflammatory responses. In mammals, DR signalling is mediated by the recruitment of several DD (death domain)‐containing molecules, such as FADD (Fas‐associated DD) and RIP1 (receptor‐interacting protein 1).

Results. To elucidate the molecular mechanisms of intracellular DR signalling in Xenopus, we have isolated cDNAs encoding xFADD (Xenopus FADD), and xRIP1 and its short isoform xRIP1β, which is produced by alternative splicing of the xRIP1 gene. These DD‐containing proteins interacted with Xenopus DR members xDR‐M1 and xDR‐M2 through their DDs in co‐transfected HEK‐293T cells. Overexpression of xFADD activated not only xCaspase 8, but also AP‐1 (activator protein 1), which reflects activation of JNK (c‐Jun N‐terminal kinase) and NF‐κB (nuclear factor κB). A comparative analysis of xRIP1, a kinase‐dead mutant of xRIP1 and xRIP1β indicated that the kinase activity of xRIP1 was required for the activation of AP‐1 and NF‐κB. Interestingly, xFADD and xRIP1 interacted with each other via their DDs, and the expression of a mutant xRIP1 containing only the DD (xRIP1‐DD) repressed the xFADD‐induced activation of NF‐κB and AP‐1. xFADD and xRIP1 synergistically induced the activation of AP‐1 and NF‐κB, both of which were partially mediated by TRAF2 (tumour‐necrosis‐factor‐receptor‐associated factor 2) and TAK1 (transforming‐growth‐factor‐β‐activated kinase 1). We also found that the activation pathways of NF‐κB induced by xDR‐M2 were inhibited by xRIP1‐DD.

Conclusions. Xenopus FADD, RIP1 and its splice variant RIP1β have been characterized. Interaction of xFADD and xRIP1 induced synergistic activation of JNK and NF‐κB. In addition, the NF‐κB activation induced by xDR‐M2 was partially mediated by xRIP1.
Ultrastructural changes of the carp (Cyprinus carpio) hepatocyte nucleolus during seasonal acclimatization
Authors: Alvarez Marco , Quezada Claudia , Molina Alfredo , Krauskopf Manuel , Vera M. Ines , Thiry Marc
Published: December 2008

Background information. The eurythermal fish carp (Cyprinus carpio) adjusts to the seasonal changes in the temperature and photoperiod of its habitat through diverse cellular and molecular mechanisms. We have observed that ribosomal biogenesis is modulated during the acclimatization process and correlates with profound phenotypic changes, reflecting a seasonal‐dependent ultrastructural appearance of the nucleolar components. Previous studies using classical techniques showed that in winter‐adapted carp the nucleolus appears to be segregated. In the present work, we have reassessed the nucleolar ultrastructural organization of the carp in summer‐ and winter‐adapted fish by using more specific cytochemical and immunocytological techniques.

Results. The acetylation method provided evidence that the nucleolar organization is different between winter‐ and summer‐adapted carp. In winter‐adapted fish the fibrillar component appears as a unique mass surrounded by several granular caps, whereas in summer‐adapted carp the fibrillar component forms few cordons surrounded by granular masses. The nucleolar structure and distribution of the condensed chromatin observed varies upon seasonal acclimatization. In winter the nucleolar chromatin is densely packed in masses that surround the nucleolus, whereas during summer it displays a rather looser organization formed by filaments that not only surround the nucleolus, but also go through the nucleolar body. Using the TdT (terminal deoxynucleotidyl transferase)‐immunogold labelling technique, we detected condensed and decondensed nucleolar chromatin, and found some labelling of fibrillar components in both seasons. When liver tissue from summer‐adapted carp was treated with AMD (actinomycin D), we observed that the rearrangement of the nucleolar components and condensed chromatin were similar to that found in winter‐adapted fish, with differences in the distribution of the perinucleolar chromatin.

Conclusions. The acetylation and TdT—immunogold labelling experiments indicated that the rearrangement of the nucleolar components of winter‐adapted carp is very similar to the AMD‐treated summer‐adapted carp nucleolus, with the latter representing the repression of the ribosomal biogenesis that occurs during the cold season. Nevertheless, the distribution of the condensed perinucleolar chromatin in winter‐adapted carp compared with AMD‐treated cells suggests that the transcription of rRNA genes in winter‐adapted fish is less strongly inhibited and does not lead to the classical segregation of the nucleolus of that described after AMD treatment. In addition, we have confirmed that carp hepatocyte nucleoli comprise only two main structural compartments: a fibrillar component and a granular component. Fibrillar centres were not observed.
Growth suppression induced by Notch1 activation involves Wnt—β‐catenin down‐regulation in human tongue carcinoma cells
Authors: Duan Li , Yao Jun , Wu Xinxing , Fan Mingwen
Published: December 2008

Background information. Involvement of Notch1 signalling in several cancers is well known, but its role in human tongue squamous cell carcinoma, one of the most common carcinomas of the human oral cavity, remains poorly characterized.

Results. Our studies demonstrated that constitutively over‐expressed active Notch1, via stable transfection of exogenous ICN (intracellular fragment of Notch), resulted in growth suppression of the human tongue cancer cell line Tca8113 in vitro and in vivo, accompanied by G0‐G1 cell cycle arrest and apoptosis. Moreover, down‐regulation of β‐catenin protein expression was observed in Tca8113 cells stably expressing active Notch1. Activated Notch1 also led to dramatic increase in p21WAF1/CIP1 and p53 expression with decreases in Skp2 (S‐phase kinase‐associated protein 2) and Bcl‐2 (B‐cell lymphocytic‐leukaemia proto‐oncogene 2) expression, which may participate in the induction of apoptosis and cell cycle arrest.

Conclusions. Since the effects of the Notch1 pathway are cell‐type specific and context‐dependent in cell types where Notch1 has an anti‐proliferative effect, down‐regulation of Wnt/β‐catenin signalling may be one of the mechanisms which induces apoptosis and cell cycle arrest.
BCR‐bound antigen is targeted to exosomes in human follicular lymphoma B‐cells1
Authors: Rialland Pascale , Lankar Danielle , Raposo Graça , Bonnerot Christian , Hubert Pascale
Published: December 2008

Background information. Exosomes are small membrane vesicles secreted by several cell types during exocytic fusion of multivesicular bodies with the plasma membrane. Exosomes from tumour cells can transfer antigens from cell to cell, a property favouring antigen‐specific immune responses in vitro and in vivo, and are thus an interesting putative therapeutic tool in human cancers. Exosomes have been well studied in EBV (Epstein—Barr virus)‐transformed human B‐cell lines; however, biological stimuli regulating exosome secretion quantitatively and/or qualitatively still remain poorly defined.

Results. We analysed the effect of the BCR stimulation on exosome release in the human follicular lymphoma B‐cell line DOHH2. We found that BCR (B‐cell receptor) triggering of DOHH2 cells induced the polarization of CD63+ MHC class II compartments. Moreover, BCR stimulation increased the release of exosome‐associated proteins in the extracellular space. Finally, we found that the BCR was expressed at the surface of exosomes, and could target a bound anti‐human IgG to these vesicles.

Conclusions. BCR can modulate the protein content of exosomes upon stimulation, and can target its bound antigen to these vesicles.
G1 phase‐dependent nucleolar accumulation of human histone H1x
Authors: Stoldt Stefan , Wenzel Dirk , Schulze Ekkehard , Doenecke Detlef , Happel Nicole
Published: December 2008

Background information: H1 histones are a protein family comprising several subtypes. Although specific functions of the individual subtypes could not be determined so far, differential roles are indicated by varied nuclear distributions as well as differential expression patterns of the H1 subtypes. Although the group of replication‐dependent H1 subtypes is synthesized during S phase, the replacement H1 subtype, H1°, is also expressed in a replication‐independent manner in non‐proliferating cells. Recently we showed, by protein biochemical analysis, that the ubiquitously expressed subtype H1x is enriched in the micrococcal nuclease‐resistant part of chromatin and that, although it shares common features with H1°, its expression is differentially regulated, since, in contrast to H1°, growth arrest or induction of differentiation did not induce an accumulation of H1x.

Results: In the present study, we show that H1x exhibits a cell‐cycle‐dependent change of its nuclear distribution. This H1 subtype showed a nucleolar accumulation during the G1 phase, and it was evenly distributed in the nucleus during S phase and G2. Immunocytochemical analysis of the intranucleolar distribution of H1x indicated that it is located mainly in the condensed nucleolar chromatin. In addition, we demonstrate that the amount of H1x protein remained nearly unchanged during S phase progression, which is in contrast to the replication‐dependent subtypes.

Conclusion: These results suggest that the differential localization of H1x provides a mechanism for a control of H1x activity by means of shuttling between nuclear subcompartments instead of a controlled turnover of the protein.
Trafficking of immature ΔF508-CFTR to the plasma membrane and its detection by biotinylation
Authors: Luo Yishan , McDonald Ken , Hanrahan John W.
Published: December 2008

Recent studies suggest that immature, core-glycosylated ΔF508-CFTR [the predominant mutant form of the CFTR (cystic fibrosis transmembrane conductance regulator)] can reach the plasma membrane under some conditions. In the present study we investigated this possibility since it has implications for understanding how therapeutics rescue the trafficking of mutant CFTR and perhaps other misfolded proteins. Core-glycosylated CFTR was labelled and pulled down on streptavidin beads after exposure to sulfo-NHS-SS-biotin [biotin attached to a reactive NHS (N-hydroxysuccinimide) ester with a disulfide spacer; molecular mass=606.7 Da]; however, intracellular proteins were also detected in the precipitates. When the R domain of CFTR was expressed in the cytosol of BHK (baby-hamster kidney) cells as a soluble polypeptide it was also labelled after surface biotinylation and pulled down on streptavidin beads. Intracellular biotinylation was reduced when cells were treated with sulfo-NHS-LC-biotin (biotin attached to a reactive NHS ester with an aminocaproic acid spacer) or sulfo-NHS-PEO12-biotin [biotin attached to a reactive NHS ester with a poly(ethylene glycol) spacer], but the reduction could be explained by the lower reactivity of these reagents. The R domain was detected on Western blots after loading <0.25% of the pulldown sample (∼0.01% of total lysate protein), a fraction that could be ascribed to cells that were permeable to ethidium homodimer-1 (molecular mass=856.8 Da) and propidium iodide (molecular mass=668.6 Da). When BHK cells were incubated at 29 °C to rescue ΔF508-CFTR trafficking, and then biotinylated and sorted to remove permeable cells, labelling of core-glycosylated ΔF508-CFTR was no longer detected although a weak signal was still observed using CFBE (cystic fibrosis bronchial epithelial) cells. These results suggest that there is weak surface expression of immature ΔF508-CFTR on airway epithelial cells and demonstrate the need to remove permeable cells when studying CFTR glycoforms by surface biotinylation.
Remote Hearing Screenings via Telehealth in a Rural Elementary School
Authors: Lancaster Paul , Krumm Mark , Ribera John , Klich Richard
Published: December 2008

Purpose

Telehealth (telepractice) is the provision of health care services using telecommunications. Telehealth technology typically has been employed to increase the level of health care access for consumers living in rural communities. In this way, audiologists can use telehealth to provide services in the rural school systems. This is important because school hearing screening programs are the foundation of educational audiology programs. Therefore, the goal of this study was to determine the feasibility of providing hearing screening services by telehealth technology to school-age children.

Method

Hearing screening services—including otoscopy, pure-tone, and immittance audiometry—were conducted on 32 children in 3rd grade attending an elementary school in rural Utah. Each child received 1 screening on-site and another through telehealth procedures.

Results

Immittance and otoscopy results were identical for on-site and telehealth screening protocols. Five children responded differently to pure-tone stimuli presented by the telehealth protocol than by the on-site protocol. However, no statistically significant difference was found for pure-tone screening results obtained by telehealth or on-site screening procedures (binomial test,
p
= .37). Likewise, overall screening results obtained by traditional and telehealth procedures were not statistically significant (binomial test,
p
= .37).

Conclusion

The results of this study suggest that school hearing screenings may be provided using telehealth technology. This study did find that 5 students performed differently to pure-tone screenings administered by the telehealth protocol in contrast to on-site hearing screening services. Further research is necessary to identify factors leading to false responses to pure-tone hearing screening when telehealth technology is used. In addition, telehealth hearing screening protocols should be conducted with participants of different age groups and experiencing a wide range of hearing loss to further clarify the value of telehealth technology.
Mechanisms of Synaptic Plasticity in the Dorsal Cochlear Nucleus: Plasticity-Induced Changes That Could Underlie Tinnitus
Authors: Tzounopoulos Thanos
Published: December 2008

Purpose

Tinnitus is the persistent perception of a subjective sound. Tinnitus is almost universally experienced in some forms. In most cases, recovery may occur in seconds, hours, or days. How does tinnitus shift from a transient condition to a lifelong disorder? Several lines of evidence, including clinical studies and animal models, indicate that the brain, rather than the inner ear, may in some cases be the site of maintenance of tinnitus. One hypothesis is that normal electrical activity in the auditory system becomes pathologically persistent due to plasticity-like mechanisms that can lead to long-term changes in the communication between neurons. A candidate site for the expression of this so-called synaptic plasticity is a region of the brainstem called the dorsal cochlear nucleus (DCN), a site of integration of acoustic and multimodal, sensory inputs.

Conclusions

Here we review recent findings on cellular mechanisms observed in the DCN that can lead to long-term changes in the synaptic strength between different neurons in the DCN. These cellular mechanisms could provide candidate signaling pathways underlying the induction (ignition) and/or the expression (maintenance) of tinnitus.
Solitary waves with weak transverse perturbations in quantum dusty plasmas
Authors: Ur-Rehman H. , Khan S. A. , Masood W. , Siddiq M.
Published: December 2008

Using the quantum hydrodynamic model, quantum dust ion-acoustic solitary waves are investigated in the presence of weak transverse perturbations. The linear dispersion relation is obtained using the Fourier analysis. The two-dimensional (2D) propagation of small amplitude nonlinear waves is studied by deriving the Kadomtsev–Petviashvili (KP) equation. The traveling wave solution of the KP equation is obtained by employing the tanh method. By dint of this solution, the effects of quantum Bohm pressure and the dust concentration on the 2D solitary structure are studied. The effect of quantum Bohm potential on the stability of the KP soliton is also investigated. The results are supported by the numerical analysis and the relevance of the present investigation in dense astrophysical environments is also pointed out.
Self-diffusion coefficients for water and organic solvents at high temperatures along the coexistence curve
Authors: Yoshida Ken , Matubayasi Nobuyuki , Nakahara Masaru
Published: December 2008

The self-diffusion coefficients D for water, benzene, and cyclohexane are determined by using the pulsed-field-gradient spin echo method in high-temperature conditions along the liquid branch of the coexistence curve: 30–350 °C (1.0–0.58 g cm−3), 30–250 °C (0.87–0.56 g cm−3), and 30–250 °C (0.77–0.48 g cm−3) for water, benzene, and cyclohexane, respectively. The temperature and density effects are separated and their origins are discussed by examining the diffusion data over a wide range of thermodynamic states. The temperature dependence of the self-diffusion coefficient for water is larger than that for organic solvents due to the large contribution of the attractive hydrogen-bonding interaction in water. The density dependence is larger for organic solvents than for water. The difference is explained in terms of the van der Waals picture that the structure of nonpolar organic solvents is determined by the packing effect due to the repulsion or exclusion volumes. The dynamic solvation shell scheme [K. Yoshida et al., J. Chem. Phys. 127, 174509 (2007)] is applied for the molecular interpretation of the translational dynamics with the aid of molecular dynamics simulation. In water at high temperatures, the velocity relaxation is not completed before the relaxation of the solvation shell (mobile-shell type) as a result of the breakdown of the hydrogen-bonding network. In contrast, the velocity relaxation of benzene is rather confined within the solvation shell (in-shell type).
Effect of interfacial roughness on dewetting behavior of polystyrene/poly(methyl methacrylate) bilayer film
Authors: Xue Longjian , Hu Benhui , Han Yanchun
Published: December 2008

The dewetting behavior of polystyrene (PS) film on poly(methyl methacrylate) (PMMA) sublayer was investigated by changing the short-range roughness of the PMMA sublayer systemically. When the bilayer film was heated to the temperature above both Tgs, the protuberances formed in both layers to reduce the system energy. By tracing the dewetting process of the PS up-layer, the dewetting velocity was found to increase with the roughness of the sublayer. It was demonstrated theoretically and experimentally that the equilibrium contact angle, the apparent equilibrium contact angle, and dewetting velocity of PS film on PMMA sublayer were determined by the roughness of PMMA sublayer.