bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Triton X‐100 and Acyclovir on Human Serum Albumin Structure
Authors: Liu Tianqing , Guo Rong
Published: December 2007

The effects of acyclovir and Triton X‐100 on the behavior of human serum albumin (HSA) in a acyclovir/HSA/H2O system were studied by UV spectroscopy, fluorescence spectroscopy and polarization, conductivity, zeta potential, and circular dichroism. Both acyclovir and Triton X‐100 affect the structure and behavior of HSA. The intrinsic fluorescence intensity, net charge of HSA and the conductivity of the system increase initially with increased acyclovir concentration, and the zeta potential of HSA decreases initially. The effects of Triton X‐100 are similar to those of acyclovir except for the non‐radiant energy transfer in the quenching process of Triton X‐100 to HSA. The associating site of HSA with acyclovir is the same as that of HSA with Triton X‐100.
Deacidification of Soybean Oil Using Membrane Processing and Subcritical Carbon Dioxide
Authors: Lai Louise L. , Soheili Kambiz C. , Artz William E.
Published: December 2007

Vegetable oils have been deacidified using supercritical carbon dioxide and membrane processing. However, the pressures required are substantially greater than those used in industry. Therefore, the feasibility of using subcritical carbon dioxide (at much lower pressures) and membrane processing to separate free fatty acids (FFA) from triacylglycerols (TAGs) was examined. First, FFA/TAG solubility tests were completed (10–25 °C and 68–136 atm). The oil samples were separated using a FilmTec NF90 or a FilmTec BW30 membrane in a dead‐end type cell. Within the range examined, the greatest solubility for oleic acid was at 25 °C and 136 atm. For soybean oil TAGs, the greatest solubility was at 20 °C and 136 atm. However, for the separation of the two components, 20 °C and 68 atm was best among the condition combinations examined. The solubility of oleic acid ranged from 0.294 to 0.455 mg/mL in subcritical carbon dioxide, while the solubility of triacylglycerols ranged from 0.066 to 0.139 mg/mL. The FilmTec BW30 membrane provided significantly better separation of FFAs from TAGs than did the NF90 membrane. Both membranes were selective for oleic acid, although the BW30 had greater selectivity for oleic acid (βoleic acid = 2.12, βTAGs = 0.24) than the NF90 membrane (βoleic acid = 1.26, βTAGs = 0.81).
Anxieties in Mainland Chinese and Singapore Chinese adolescents in comparison with the American norm
Authors: Li Huijun , Ang Rebecca P. , Lee Jiyoon
Published: December 2007

There is a growing literature base on child and adolescent anxiety. Cross‐cultural research on child and adolescent anxiety, however, has been relatively limited. This study examined whether there were similarities and differences in the self reported anxieties in Mainland Chinese and Singapore Chinese adolescents (12–17 years of age), and whether these similarities or differences were related to gender and/or grade. This study also compared anxiety levels of Mainland Chinese and Singapore Chinese adolescents with the American normative sample (12–17 years of age). The results indicate that the levels of anxieties did not differ based on country (China and Singapore). Gender differences were evident. Gender and grade interaction effects were found on the anxiety scales. Mixed results were found when comparing Mainland Chinese and Singapore Chinese with the American normative sample on the different anxiety scales.
The influence of natural enemies on wing induction in Aphis fabae and Megoura viciae (Hemiptera: Aphididae)
Authors: Kunert G. , Schmoock-Ortlepp K. , Reissmann U. , Creutzburg S. , Weisser W.W.
Published: December 2007

Previous studies have shown that the aphid species, Aphis fabae Scopoli and Megoura viciae Buckton, do not produce winged offspring in the presence of natural enemies, in contrast to results for the pea aphid (Acyrthosiphon pisum (Harris)) and the cotton aphid (Aphis gossypii Glover); but these studies did not involve exposing aphids directly to natural enemies. We exposed colonies of both A. fabae and M. viciae to foraging lacewing (Chrysoperla carnea (Stephens)) larvae and found that the predators did not induce winged morphs among offspring compared to unexposed controls. Colonies of A. fabae responded to an increase in aphid density with increasing winged morph production, while such response was not found for M. viciae. We suggest that different aphid species differ in their susceptibility to natural enemy attack, as well as in their sensitivity to contact.
Comparison of five allopatric fruit fly parasitoid populations (Psyttaliaspecies) (Hymenoptera: Braconidae) from coffee fields using morphometric and molecular methods
Authors: Billah M.K. , Kimani-Njogu S.W. , Wharton R.A. , Woolley J.B. , Masiga D.
Published: December 2007

Morphometric studies of five allopatric parasitoid populations (genusPsyttaliaWalker) from coffee plantations in Cameroon (Nkolbisson), Ghana (Tafo) and Kenya (Rurima, Ruiru and Shimba Hills) and one non-coffee population (from Muhaka, Kenya) were compared with individuals ofPsyttalia concolor(Szépligeti), a species released in several biological control programmes in the Mediterranean Region since the 20th Century. Analyses of wing vein measurements showed the second submarginal cell of the fore wing and its adjoining veins had the heaviest principal component weights and served as the main contributing variables in the diagnostic differentiation of the populations. Two populations (Rurima and Ruiru) were found to be the closest to each other and with the strongest phenetic affinity towardP.concolor(and forming one cluster). Populations from Shimba Hills (of unknown identity), Nkolbisson (P. perproximus(Silvestri)) and Tafo formed a second cluster and were separated fromP. concolor. Comparison using amplified fragment length polymorphism (AFLP) also showed the Shimba, Nkolbisson and Tafo populations forming a cluster in a dendrogram generated from their genetic distances, with the Shimba and Tafo populations placed as the most closely related species. Based on consistent morphological similarities, morphometric and ecological data coupled with the genetic evidence from AFLP data, the Shimba population is suggested as belonging to theP. perproximusgroup and, thus, represents a new occurrence record in Kenya. Our results also support earlier conclusion from cross mating data that populations from Rurima and Ruiru belong to thePsyttalia concolorspecies-group.
Effects ofHelicoverpa armigera(Noctuidae, Lepidoptera) host stages on some developmental parameters of the uniparental endoparasitoidMeteorus pulchricornis (Braconidae, Hymenoptera)
Authors: Ya-hui Liu , Bao-ping Li
Published: December 2007

A single choice test was performed to examine developmental strategies in the uniparental endoparasitoidMeteorus pulchricornisand its host, the cotton bollwormHelicoverpa armigera. The results support the dome-shaped model in which the fitness functions are ‘dome-shaped’ relative to size (and age) of host at parasitism. Older and, hence, larger host larvae were simply not better hosts for the developing parasitoids. Although parasitoid size (measured as cocoon weight and adult hind tibia length) was positively correlated with host instars at parasitism, parasitoids developing in larger hosts (L5and L6) suffered much higher mortality than conspecifics developing in smaller hosts (L2–L4). Furthermore, egg-to-adult development time inM. pulchricorniswas significantly longer in older host larvae (L4–L6) than in the younger. Performance ofM. pulchricornis, as indicated by fitness-related traits, strongly suggests that the L3host is the most suitable for survival, growth and development of the parasitoid, followed by both L2and L4hosts; whereas, L1, L5and L6are the least favourable hosts. The oviposition tendency ofM. pulchricornis, represented by parasitism level, was not perfectly consistent with the performance of the offspring; L2–L4hosts, although with the same parasitism level, had offspring parasitoids with differences in fitness-related performance. Larval development inHelicoverpa armigerawas usually suspended, but occasionally advanced, in the final instar.
A radar study of emigratory flight and layer formation by insects at dawn over southern Britain
Authors: Reynolds D.R. , Smith A.D. , Chapman J.W.
Published: December 2007

Radar observations have consistently shown that high-altitude migratory flight in insects generally occurs after mass take-off at dusk or after take-off over a more extended period during the day (in association with the growth of atmospheric convection). In this paper, we focus on a less-studied third category of emigration – the ‘dawn take-off’ – as recorded by insect-monitoring radars during the summer months in southern England. In particular, we describe occasions when dawn emigrants formed notable layer concentrations centred at altitudes ranging fromca. 240 m to 700 m above ground, very probably due to the insects responding to local temperature maxima in the atmosphere, such as the tops of inversions. After persisting for several hours through the early morning, the layers eventually merged into the insect activity building up later in the morning (from 06.00–08.00 h onwards) in conjunction with the development of daytime convection. The species forming the dawn layers have not been positively identified, but their masses lay predominantly in the 16–32 mg range, and they evidently formed a fauna quite distinct from that in flight during the previous night. The displacement and common orientation (mutual alignment) characteristics of the migrants are described.
Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds
Authors: Saska P. , van der Werf W. , de Vries E. , Westerman P.R.
Published: December 2007

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris,Lamium amplexicaule,Poa annuaandStellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order:C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.
Hearing a voice in the noise: auditory hallucinations and speech perception
Authors: Vercammen A. , de Haan E. H. F. , Aleman A.
Published: December 2007

Background

It has recently been suggested that auditory hallucinations are the result of a criterion shift when deciding whether or not a meaningful signal has emerged. The approach proposes that a liberal criterion may result in increased false-positive identifications, without additional perceptual deficit. To test this hypothesis, we devised a speech discrimination task and used signal detection theory (SDT) to investigate the underlying cognitive mechanisms.

Method

Schizophrenia patients with and without auditory hallucinations and a healthy control group completed a speech discrimination task. They had to decide whether a particular spoken word was identical to a previously presented speech stimulus, embedded in noise. SDT was used on the accuracy data to calculate a measure of perceptual sensitivity (Az) and a measure of response bias (β). Thresholds for the perception of simple tones were determined.

Results

Compared to healthy controls, perceptual thresholds were higher and perceptual sensitivity in the speech task was lower in both patient groups. However, hallucinating patients showed increased sensitivity to speech stimuli compared to non-hallucinating patients. In addition, we found some evidence of a positive response bias in hallucinating patients, indicating a tendency to readily accept that a certain stimulus had been presented.

Conclusions

Within the context of schizophrenia, patients with auditory hallucinations show enhanced sensitivity to speech stimuli, combined with a liberal criterion for deciding that a perceived event is an actual stimulus.
Examining rhythmic and metric practices in Led Zeppelin’s musical style
Authors: BRACKETT JOHN
Published: December 2007

In this essay, I examine how aspects of rhythm and metre play a fundamental role in shaping and defining Led Zeppelin’s musical style. At the same time, I will show how Led Zeppelin was able to modify, manipulate, and develop pre-existing musical models and forms through various rhythmic and metric strategies. Comparative analyses will be used in an effort to show how Led Zeppelin’s flexible conception of rhythm and metre enabled the band to put their own stylistic ‘stamp’ on (i) specific musical genres (‘The Crunge’ and the song’s relation to James Brown-style funk), (ii) their riff constructions (‘Black Dog’ in relation to Fleetwood Mac’s ‘Oh Well’), and (iii) their cover versions (‘Dazed and Confused’). Drawing upon my analytical points, I re-visit the complex issues that persist regarding the possibility that Led Zeppelin even has an ‘original’ or ‘unique’ style given their often overt reliance upon earlier musical models and forms. Therefore, in my conclusion, I argue that the development of any artist or group’s individual style necessarily involves the ability to assimilate and transform pre-existing musical features – features such as rhythm and metre – in novel ways and where issues relating to musical style intersect with influence.
2·5×6 metres of space: Japanese music coffeehouses and experimental practices of listening
Authors: NOVAK DAVID
Published: December 2007

This article describes a specific history of technological mediation in the circulation of popular music by examining local practices of listening to recordings in Japanese kissaten (often shortened to kissa and meaning, loosely, ‘coffeehouse’). In postwar music kissaten, Japanese listeners were socialised to recordings of foreign music through new modes of hyper-attentive listening. While jazz kissa (though famous as crucibles for radical pro-democracy politics and the explosion of modern urban cool in post-war Japanese cities) encouraged local listeners to develop musical appreciation through the stylistic classification of distant recorded sources, later experimental music kissa helped forge unique local performance scenes by disturbing received modes of generic classification in favour of ‘Noise’. I recount the emergence of a genre called ‘Noise’ in the story of a 1970s Kyoto ‘free’ kissa Drugstore, whose countercultural clientele came to represent ‘Noise’ as a new musical style in its transnational circulation during the 1990s. This ethnographic history presents the music kissa as a complicated translocal site that articulates the cultural marginality of Japanese popular music reception in an uneven global production; but which also helps to develop virtuosic experimental practices of listening through which imported recordings are recontextualised, renamed and recreated.
Ontology-based models in pervasive computing systems
Authors: YE JUAN , COYLE LORCAN , DOBSON SIMON , NIXON PADDY
Published: December 2007

Pervasive computing is by its nature open and extensible, and must integrate the information from a diverse range of sources. This leads to a problem of information exchange, so sub-systems must agree on shared representations. Ontologies potentially provide a well-founded mechanism for the representation and exchange of such structured information. A number of ontologies have been developed specifically for use in pervasive computing, none of which appears to cover adequately the space of concerns applicable to application designers. We compare and contrast the most popular ontologies, evaluating them against the system challenges generally recognized within the pervasive computing community. We identify a number of deficiencies that must be addressed in order to apply the ontological techniques successfully to next-generation pervasive systems.
WEIGHT OF THE SHORTEST PATH TO THE FIRST ENCOUNTERED PEER IN A PEER GROUP OF SIZE m
Authors: Van Mieghem P. , Tang S.
Published: December 2007

We model the weight (e.g., delay, distance, or cost) from an arbitrary node to the nearest (in weight) peer in a peer-to-peer (P2P) network. The exact probability generating function and an asymptotic analysis is presented for a random graph with independent and identically distributed exponential link weights. The asymptotic distribution function is a Fermi–Dirac distribution that frequently appears in statistical physics. The good agreement with simulation results for relatively small P2P networks makes the asymptotic formula for the probability density function useful for estimating the minimal number of peers to offer an acceptable quality (delay or latency).
Spatial mapping of the b value at Mount Etna, Italy, using earthquake data recorded from 1999 to 2005
Authors: Murru M. , Console R. , Falcone G. , Montuori C. , Sgroi T.
Published: December 2007

The spatial pattern of the b value of the frequency‐magnitude relation has been analyzed using gridding techniques beneath Mount Etna, Italy. A regional data set of 2900 events with Md (duration magnitude) ≥1.5 up to 15 km depth occurring between August 1999 and December 2005 has been used. Two regions with an abnormally high b value have been found, one centered beneath the southern part of the Valle del Bove, above the 6 km below sea level (bsl) deep basement, and the other beneath the summit region 2 km bsl east of the Central Craters. We can infer that these high b value anomalies are regions of increased crack density, and/or high pore pressure, related to the presence of nearby magma storage. This interpretation is supported by all the available geophysical evidence, such as tomographic studies and geodetic deformation measurements. The data set has also been subdivided into five periods, corresponding to different phases of volcanic activity: 2001 preeruption, 2001 eruptive, 2002–2003 preeruption, 2002–2003 eruptive, and 2002–2003 posteruption. The minimum magnitude of completeness, Mc, and the b value were computed for each period. A volume of anomalously high b values can be observed in each of these periods (except for the 2002–2003 preeruption interval). This approach has allowed the detection of the transient presence of magmatic intrusions during the various periods evaluated.
Spatial interpolation and filtering of surface current data based on open‐boundary modal analysis
Authors: Kaplan David M. , Lekien Francois
Published: December 2007

The use of high‐frequency (HF) radar surface current measurements are limited by spatial coverage gaps and sparse sampling. The normal mode (NMA) and open‐boundary mode (OMA) current decomposition techniques developed by Lipphardt et al. (2000) and Lekien et al. (2004), respectively, produce smooth two‐dimensional current fields by fitting data to a set of spatial modes. These methods have the advantages of incorporating the coastal boundary condition and providing a controllable level of spatial smoothing. While computation of and fitting to modes has been previously examined, variations and limitations of the technique have not been fully explored. Here we expand on the original OMA algorithm to incorporate radial currents produced by individual HF radars. Assimilating radial measurements maximizes use of available data and avoids the additional step and error of creating vector currents from radial data. We also develop techniques for dealing with spatially nonuniform data distributions and data gaps. Estimates of measurement error are propagated to evaluate the uncertainty of interpolated current fields. We illustrate our findings and assess the robustness of the OMA technique for calculating currents, divergences, and vorticities using HF radar data from Bodega Bay and Monterey Bay, California. Though care must be taken when using the technique as occasional shortage of data (e.g., temporary failure of a radar station) can produce erroneous fitted currents, OMA provides a robust mechanism for interpolating and filtering two‐dimensional velocity measurements. Furthermore, OMA‐derived errors provide a transparent and useful estimate of spatial patterns of uncertainty.
Variability of recent ground surface temperature changes in the Albuquerque basin, central New Mexico
Authors: Reiter Marshall
Published: December 2007

Subsurface temperature measurements have been taken at four sites over a large area within the Albuquerque basin, central New Mexico. These data were taken in the unsaturated zone in order to avoid potential water movement in the saturated zone, so that a better estimate of surface temperature change might be realized. The data imply surface temperature change is not constant across the area. Unexpectedly, large upward water flow is suggested at one site having a very unique hydrogeologic environment. Different amounts of surface warming, likely caused by land cover change and encroaching urbanization, are estimated at two other sites. Data from a fourth site do not indicate a statistically significant surface temperature change, although the effects of urbanization and possibly increased evaporation in the past several years add ambiguity to the interpretation. These four sites indicate the potential variability of phenomena affecting subsurface temperatures in the Albuquerque basin.
Sensitivity of global CO simulations to uncertainties in biomass burning sources
Authors: Bian H. , Chin M. , Kawa S. R. , Duncan B. , Arellano A. , Kasibhatla P.
Published: December 2007

One of the largest uncertainties for the modeling of tropospheric carbon monoxide (CO) concentration is the timing, location, and magnitude of biomass burning emissions. We investigate the sensitivity of simulated CO in the Unified Chemistry Transport Model (UCTM) to several biomass burning emissions, including four bottom‐up and two top‐down inventories. We compare the sensitivity experiments with observations from MOPITT, surface and airborne NOAA Global Monitoring Division network data, and the TRACE‐P field campaign. The variation of the global annual emissions of these six biomass burning inventories is within 30%; however, their regional variations are often much higher (factor of 2–5). These uncertainties translate to about 6% variation in the global simulated CO but more than a 100% variation in some regions. The annual mean CO variation is greater in the Southern Hemisphere (>12%) than in the Northern Hemisphere (<5%), largely because biomass burning is a higher percentage of the total source in the Southern Hemisphere. Comparisons with CO observations indicate that each model inventory has its strengths and shortcomings, and these regional variations are examined. Overall the model CO concentrations are within the observed range of variability at most stations including Ascension Island, which is strongly influenced by fire emissions. In addition, we discuss the systematic biases that exist in the inventories developed by the similar methodologies and original satellite data.
Geodynamic evolution of the SW Europe Variscides
Authors: Ribeiro António , Munhá José , Dias Rui , Mateus António , Pereira Eurico , Ribeiro Luísa , Fonseca Paulo , Araújo Alexandre , Oliveira Tomás , Romão José , Chaminé Hélder , Coke Carlos , Pedro Jorge
Published: December 2007

The early evolution of SW Europe Variscides started by opening of the Rheic ocean at ∼500 Ma, splitting Avalonia from Armorica/Iberia. Subduction on the SE side of Rheic generated the Paleotethys back‐arc basin (430–390 Ma, splitting Armorica from Iberia), with development of Porto‐Tomar‐Ferreira do Alentejo (PTFA) dextral transform defining the boundary between continental Armorica and Finisterra microplate to the W. Obduction of Paleotethys was followed by Armorica/Iberia collision and emplacement of NW Iberian Allochthonous Units at 390–370 Ma, whereas toward the west of PTFA, there was antithetic ophiolite obduction (Beja‐Acebuches and Rheic ophiolites plus Finisterra continental slices) on top of Ossa‐Morena Zone, with simultaneous development of eclogites and orogenic magmatism under a flake–double wedge tectonic regime. Continued convergence (<370 Ma) proceeded by intracontinental deformation, with progressive tightening of the Ibero‐Armorican Arc through dextral transpression on the Cantabrian Indentor, from Iberia to Armorica. The proposed model is discussed at the light of the driving mechanism of “soft plate tectonics.”
Comparison of height‐averaged and point‐measured capillary pressure–saturation relations for sands using a modified Tempe cell
Authors: Sakaki Toshihiro , Illangasekare Tissa H.
Published: December 2007

Tempe cells and similar devices are often used for measurements of capillary pressure versus saturation relationships (retention curves) of soils. Average water saturation within the sample is often used as the representative saturation. For cases where the saturation distribution along the cell height is nonuniform, use of the height‐averaged water saturation artificially smoothes the retention curve when the capillary pressure head reaches the displacement pressure head. This leads to an inaccurate representation of the retention curve in flow modeling. For nine test sands with a wide range of displacement pressure head values (6–78 cm of water), height‐averaged and point‐measured retention curves were simultaneously obtained to investigate the effect of the height‐averaging procedure. A Tempe cell was used, which was modified by installing a small time domain reflectometry probe and a tensiometer at the midpoint of the sample height to measure water saturation and pressure, respectively. When the sample height is large relative to the displacement pressure head, the bulk drainage (initial drainage at the top of the sample) leads to inaccuracies in the determination of retention curves. For such cases, point‐measured saturation should be used, otherwise height correction is necessary.
A slab in depth: Three‐dimensional geometry and evolution of the Indo‐Australian plate
Authors: Richards Simon , Lister Gordon , Kennett Brian
Published: December 2007

Geoscientists use plate tectonics to explain many aspects of both continental evolution and evolution of the planet as a whole. The subduction of material at convergent plate boundaries forms a fundamental component to the theory of plate tectonics. Plates, continents, subduction zones, and spreading centers all exhibit motion and geometric evolution, so to try and resolve the past geometries of the planet, geologists have utilized plate tectonic reconstructions. Here we present a three‐dimensional image of the subducted Indo‐Australian plate below southeast Asia and show that the geometry of the subducted slab at depth is intimately related to the geometric evolution of SE Asia over the past 50 Ma, including the collision of India with the Asian continent. We show how the once semicontinuous subducting Indo‐Australian plate has been segmented during collision between India, Australian, and the subduction margin to the north. Thus we have found that the geometry of the subducted plate should form a key component to the interpretation of the evolution of Earth's surface, as complexities and evolution of the subducted plate are manifest in the evolution of the overriding plate.
Quantifying the influence of anthropogenic surface processes and inhomogeneities on gridded global climate data
Authors: McKitrick Ross R. , Michaels Patrick J.
Published: December 2007

Local land surface modification and variations in data quality affect temperature trends in surface‐measured data. Such effects are considered extraneous for the purpose of measuring climate change, and providers of climate data must develop adjustments to filter them out. If done correctly, temperature trends in climate data should be uncorrelated with socioeconomic variables that determine these extraneous factors. This hypothesis can be tested, which is the main aim of this paper. Using a new database for all available land‐based grid cells around the world we test the null hypothesis that the spatial pattern of temperature trends in a widely used gridded climate data set is independent of socioeconomic determinants of surface processes and data inhomogeneities. The hypothesis is strongly rejected (P = 7.1 × 10−14), indicating that extraneous (nonclimatic) signals contaminate gridded climate data. The patterns of contamination are detectable in both rich and poor countries and are relatively stronger in countries where real income is growing. We apply a battery of model specification tests to rule out spurious correlations and endogeneity bias. We conclude that the data contamination likely leads to an overstatement of actual trends over land. Using the regression model to filter the extraneous, nonclimatic effects reduces the estimated 1980–2002 global average temperature trend over land by about half.
Developmentally regulated association of plastid division protein FtsZ1 with thylakoid membranes in Arabidopsis thaliana
Authors: El-Kafafi El-Sayed , Karamoko Mohamed , Pignot-Paintrand Isabelle , Grunwald Didier , Mandaron Paul , Lerbs-Mache Silva , Falconet Denis
Published: December 2007

FtsZ is a key protein involved in bacterial and organellar division. Bacteria have only one ftsZ gene, while chlorophytes (higher plants and green alga) have two distinct FtsZ gene families, named FtsZ1 and FtsZ2. This raises the question of why chloroplasts in these organisms need distinct FtsZ proteins to divide. In order to unravel new functions associated with FtsZ proteins, we have identified and characterized an Arabidopsis thaliana FtsZ1 loss-of-function mutant. ftsZ1-knockout mutants are impeded in chloroplast division, and division is restored when FtsZ1 is expressed at a low level. FtsZ1-overexpressing plants show a drastic inhibition of chloroplast division. Chloroplast morphology is altered in ftsZ1, with chloroplasts having abnormalities in the thylakoid membrane network. Overexpression of FtsZ1 also induced defects in thylakoid organization with an increased network of twisting thylakoids and larger grana. We show that FtsZ1, in addition to being present in the stroma, is tightly associated with the thylakoid fraction. This association is developmentally regulated since FtsZ1 is found in the thylakoid fraction of young developing plant leaves but not in mature and old plant leaves. Our results suggest that plastid division protein FtsZ1 may have a function during leaf development in thylakoid organization, thus highlighting new functions for green plastid FtsZ.
The essential role for c-Ski in mediating TGF-β1-induced bi-directional effects on skin fibroblast proliferation through a feedback loop
Authors: Liu Xia , Li Ping , Liu Ping , Xiong Renping , Zhang En , Chen Xingyun , Gu Dayong , Zhao Yan , Wang Zhengguo , Zhou Yuanguo
Published: December 2007

The bi-directional regulation of TGF-β1 (transforming growth factor-β1) on fibroblast proliferation with stimulation at low concentration, but inhibition at high concentration, has important significance during tissue repair. The mechanism has not been defined. c-Ski is a major co-repressor of TGF-β1/Smad3 signalling; however, the exact role of c-Ski in the bi-directional regulation of fibroblast proliferation remains to be determined. In the present study, we established a dose–effect relationship of bi-directional regulation of TGF-β1-mediated proliferation in rat skin fibroblasts, and found that c-Ski overexpression promoted fibroblast proliferation by inhibiting Smad3 activity. Importantly, c-Ski expression was decreased at the high concentration of TGF-β1, but increased at the low concentration of TGF-β1. This dose-dependent change in TGF-β1 action did not affect Smad3 phosphorylation or nuclear translocation, but altered Smad3 DNA-binding activity, transcriptional activity and expression of the downstream gene p21 that both increased at the high concentration and decreased at the low concentration. Furthermore, c-Ski overexpression exerted synergistic stimulation with TGF-β1 at the low concentration, but reversed the inhibitory effect of TGF-β1 at high concentrations, while knockdown of c-Ski by RNA interference abrogated bi-directional role of TGF-β1 on fibroblast proliferation. Thus our data reveal a new mechanism for this bi-directional regulation, i.e. c-Ski expression change induced by low or high TGF-β1 concentration in turn determines the promoting or inhibiting effects of TGF-β1 on fibroblast proliferation, and suggests an important role of c-Ski that modulates the local availability of TGF-β1 within the wound repair microenvironment.
The far and distal enhancers in the CYP3A4 gene co-ordinate the proximal promoter in responding similarly to the pregnane X receptor but differentially to hepatocyte nuclear factor-4α
Authors: Liu Fu-Jun , Song Xiulong , Yang Dongfang , Deng Ruitang , Yan Bingfang
Published: December 2007

CYP3A4 (cytochrome P450 3A4) is involved in the metabolism of more than 50% of drugs and other xenobiotics. The expression of CYP3A4 is induced by many structurally dissimilar compounds. The PXR (pregnane X receptor) is recognized as a key regulator for the induction, and the PXR-directed transactivation of the CYP3A4 gene is achieved through a co-ordinated mechanism of the distal module with the proximal promoter. Recently, a far module was found to support constitutive expression of CYP3A4. The far module, like the distal module, is structurally clustered by a PXR response element (F-ER6) and elements recognized by HNF-4α (hepatocyte nuclear receptor-4α). We hypothesized that the far module supports PXR transactivation of the CYP3A4 gene. Consistent with the hypothesis, fusion of the far module to the proximal promoter of CYP3A4 markedly increased rifampicin-induced reporter activity. The increase was synergistically enhanced when both the far and distal modules were fused to the proximal promoter. The increase, however, was significantly reduced when the F-ER6 was disrupted. Chromatin immunoprecipitation detected the presence of PXR in the far module. Interestingly, HNF-4α increased the activity of the distal-proximal fused promoter, but decreased the activity of the far-proximal fused promoter. Given the fact that induction of CYP3A4 represents an important detoxification mechanism, the functional redundancy and synergistic interaction in supporting PXR transactivation suggest that the far and distal modules ensure the induction of CYP3A4 during chemical insults. The difference in responding to HNF-4α suggests that the magnitude of the induction is under control through various transcriptional networks.
Hypoxia, via stabilization of the hypoxia-inducible factor HIF-1α, is a direct and sufficient stimulus for brain-type natriuretic peptide induction
Authors: Weidemann Alexander , Klanke Bernd , Wagner Michael , Volk Tilmann , Willam Carsten , Wiesener Michael S. , Eckardt Kai-Uwe , Warnecke Christina
Published: December 2007

BNP (brain-type natriuretic peptide) is a cardiac hormone with systemic haemodynamic effects as well as local cytoprotective and antiproliferative properties. It is induced under a variety of pathophysiological conditions, including decompensated heart failure and myocardial infarction. Since regional hypoxia is a potential common denominator of increased wall stretch and myocardial hypoperfusion, we investigated the direct effects of hypoxia on BNP expression, and the role of the HIF (hypoxia-inducible transcription factor) in BNP regulation. Using an RNase protection assay we found a strong hypoxic induction of BNP mRNA expression in different cell lines and in cultured adult rat cardiomyocytes. Systemic hypoxia and exposure to 0.1% CO induced BNP expression in the rodent myocardium in vivo, although this was at a lower amplitude. BNP promoter-driven luciferase expression increased 10-fold after hypoxic stimulation in transient transfections. Inactivation of four putative HREs (hypoxia-response elements) in the promoter by site-directed mutagenesis revealed that the HRE at −466 nt was responsible for hypoxic promoter activation. A functional CACAG motif was identified upstream of this HRE. The HIF-1 complex bound specifically and inducibly only to the HRE at −466 nt, as shown by EMSA (electrophoretic mobility-shift assay) and ChIP (chromatin immunoprecipitation). siRNA (small interfering RNA)-mediated knockdown of HIF-1α, but not HIF-2α, interfered with hypoxic BNP mRNA induction and BNP promoter activation, confirming that BNP is a specific HIF-1α target gene. In conclusion, BNP appears to be part of the protective program steered by HIF-1 in response to oxygen deprivation. Induction of BNP may therefore contribute to the potential benefits of pharmacological HIF inducers in the treatment of ischaemic heart disease and heart failure.
Genomic location of the human RNA polymerase II general machinery: evidence for a role of TFIIF and Rpb7 at both early and late stages of transcription
Authors: Cojocaru Marilena , Jeronimo Célia , Forget Diane , Bouchard Annie , Bergeron Dominique , Côte Pierre , Poirier Guy G. , Greenblatt Jack , Coulombe Benoit
Published: December 2007

The functions ascribed to the mammalian GTFs (general transcription factors) during the various stages of the RNAPII (RNA polymerase II) transcription reaction are based largely on in vitro studies. To gain insight as to the functions of the GTFs in living cells, we have analysed the genomic location of several human GTF and RNAPII subunits carrying a TAP (tandem-affinity purification) tag. ChIP (chromatin immunoprecipitation) experiments using anti-tag beads (TAP-ChIP) allowed the systematic localization of the tagged factors. Enrichment of regions located close to the TIS (transcriptional initiation site) versus further downstream TRs (transcribed regions) of nine human genes, selected for the minimal divergence of their alternative TIS, were analysed by QPCR (quantitative PCR). We show that, in contrast with reports using the yeast system, human TFIIF (transcription factor IIF) associates both with regions proximal to the TIS and with further downstream TRs, indicating an in vivo function in elongation for this GTF. Unexpectedly, we found that the Rpb7 subunit of RNAPII, known to be required only for the initiation phase of transcription, remains associated with the polymerase during early elongation. Moreover, ChIP experiments conducted under stress conditions suggest that Rpb7 is involved in the stabilization of transcribing polymerase molecules, from initiation to late elongation stages. Together, our results provide for the first time a general picture of GTF function during the RNAPII transcription reaction in live mammalian cells and show that TFIIF and Rpb7 are involved in both early and late transcriptional stages.
SFH2 regulates fatty acid synthase activity in the yeast Saccharomyces cerevisiae and is critical to prevent saturated fatty acid accumulation in response to haem and oleic acid depletion
Authors: Desfougères Thomas , Ferreira Thierry , Bergès Thierry , Régnacq Matthieu
Published: December 2007

The yeast Saccharomyces cerevisiae is a facultative anaerobic organism. Under anaerobiosis, sustained growth relies on the presence of exogenously supplied unsaturated fatty acids and ergosterol that yeast is unable to synthesize in the absence of oxygen or upon haem depletion. In the absence of exogenous supplementation with unsaturated fatty acid, a net accumulation of SFA (saturated fatty acid) is observed that induces significant modification of phospholipid profile [Ferreira, Régnacq, Alimardani, Moreau-Vauzelle and Bergès (2004) Biochem. J. 378, 899–908]. In the present paper, we focus on the role of SFH2/CSR1, a hypoxic gene related to SEC14 and its involvement in lipid metabolism upon haem depletion in the absence of oleic acid supplementation. We observed that inactivation of SFH2 results in enhanced accumulation of SFA and phospholipid metabolism alterations. It results in premature growth arrest and leads to an exacerbated sensitivity to exogenous SFA. This phenotype is suppressed in the presence of exogenous oleic acid, or by a controlled expression of FAS1, one of the two genes encoding FAS. We present several lines of evidence to suggest that Sfh2p and oleic acid regulate SFA synthase in yeast at different levels: whereas oleic acid acts on FAS2 at the transcriptional level, we show that Sfh2p inhibits fatty acid synthase activity in response to haem depletion.
Diacylglycerol kinases: at the hub of cell signalling
Authors: Mérida Isabel , Ávila-Flores Antonia , Merino Ernesto
Published: December 2007

DGKs (diacylglycerol kinases) are members of a unique and conserved family of intracellular lipid kinases that phosphorylate DAG (diacylglycerol), catalysing its conversion into PA (phosphatidic acid). This reaction leads to attenuation of DAG levels in the cell membrane, regulating a host of intracellular signalling proteins that have evolved the ability to bind this lipid. The product of the DGK reaction, PA, is also linked to the regulation of diverse functions, including cell growth, membrane trafficking, differentiation and migration. In multicellular eukaryotes, DGKs provide a link between lipid metabolism and signalling. Genetic experiments in Caenorhabditis elegans, Drosophila melanogaster and mice have started to unveil the role of members of this protein family as modulators of receptor-dependent responses in processes such as synaptic transmission and photoreceptor transduction, as well as acquired and innate immune responses. Recent discoveries provide new insights into the complex mechanisms controlling DGK activation and their participation in receptor-regulated processes. After more than 50 years of intense research, the DGK pathway emerges as a key player in the regulation of cell responses, offering new possibilities of therapeutic intervention in human pathologies, including cancer, heart disease, diabetes, brain afflictions and immune dysfunctions.
Getting to grips with the plant metabolic network
Authors: Sweetlove Lee J. , Fell David , Fernie Alisdair R.
Published: December 2007

Research into plant metabolism has a long history, and analytical approaches of ever-increasing breadth and sophistication have been brought to bear. We now have access to vast repositories of data concerning enzymology and regulatory features of enzymes, as well as large-scale datasets containing profiling information of transcripts, protein and metabolite levels. Nevertheless, despite this wealth of data, we remain some way off from being able to rationally engineer plant metabolism or even to predict metabolic responses. Within the past 18 months, rapid progress has been made, with several highly informative plant network interrogations being discussed in the literature. In the present review we will appraise the current state of the art regarding plant metabolic network analysis and attempt to outline what the necessary steps are in order to further our understanding of network regulation.
Annexins sense changes in intracellular pH during hypoxia
Authors: Monastyrskaya Katia , Tschumi Fabian , Babiychuk Eduard B. , Stroka Deborah , Draeger Annette
Published: December 2007

The pHi (intracellular pH) is an important physiological parameter which is altered during hypoxia and ischaemia, pathological conditions accompanied by a dramatic decrease in pHi. Sensors of pHi include ion transport systems which control intracellular Ca2+ gradients and link changes in pHi to functions as diverse as proliferation and apoptosis. The annexins are a protein family characterized by Ca2+-dependent interactions with cellular membranes. Additionally, in vitro evidence points to the existence of pH-dependent, Ca2+-independent membrane association of several annexins. We show that hypoxia promotes the interaction of the recombinant annexin A2–S100A10 (p11) and annexin A6 with the plasma membrane. We have investigated in vivo the influence of the pHi on the membrane association of human annexins A1, A2, A4, A5 and A6 tagged with fluorescent proteins, and characterized this interaction for endogenous annexins present in smooth muscle and HEK (human embryonic kidney)-293 cells biochemically and by immunofluorescence microscopy. Our results show that annexin A6 and the heterotetramer A2–S100A10 (but not annexins A1, A4 and A5) interact independently of Ca2+ with the plasma membrane at pH 6.2 and 6.6. The dimerization of annexin A2 within the annexin A2–S100A10 complex is essential for the pH-dependent membrane interaction at this pH range. The pH-induced membrane binding of annexins A6 and A2–S100A10 might have consequences for their functions as membrane organizers and channel modulators.
Structure of the A20 OTU domain and mechanistic insights into deubiquitination
Authors: Komander David , Barford David
Published: December 2007

The NF-κB (nuclear factor κB) regulator A20 antagonises IKK [IκB (inhibitor of κB) kinase] activation by modulating Lys63-linked polyubiquitination of cytokine-receptor-associated factors including TRAF2/6 (tumour-necrosis-factor-receptor-associated factor 2/6) and RIP1 (receptor-interacting protein 1). In the present paper we describe the crystal structure of the N-terminal OTU (ovarian tumour) deubiquitinase domain of A20, which differs from other deubiquitinases but shares the minimal catalytic core with otubain-2. Analysis of conserved surface regions allows prediction of ubiquitin-binding sites for the proximal and distal ubiquitin molecules. Structural and biochemical analysis suggests a novel architecture of the catalytic triad, which might be present in a subset of OTU domains including Cezanne and TRABID (TRAF-binding domain). Biochemical analysis shows a preference of the isolated A20 OTU domain for Lys48-linked tetraubiquitin in vitro suggesting that additional specificity factors might be required for the physiological function of A20 in cells.
Therapeutic potential of stem cells in lung disease: progress and pitfalls
Authors: Loebinger Michael R. , Aguilar Susana , Janes Sam M.
Published: December 2007

There has been increasing excitement over the last few years with the suggestion that exogenous stem cells may offer new treatment options for a wide range of diseases. Within respiratory medicine, these cells have been shown to have the ability to differentiate and function as both airway and lung parenchyma epithelial cells in both in vitro and increasingly in vivo experiments. The hypothesis is that these cells may actively seek out damaged tissue to assist in the local repair, and the hope is that their use will open up new cellular and genetic treatment modalities. Such is the promise of these cells that they are being rushed from the benchside to the bedside with the commencement of early clinical trials. However, important questions over their use remain and the field is presently littered with controversy and uncertainty. This review evaluates the progress made and the pitfalls encountered to date, and critically assesses the evidence for the use of stem cells in lung disease.