bluuebunny/crossref_metadata_2025 huggingface dataset:
Silk feeding as an alternative foraging tactic in a kleptoparasitic spider under seasonally changing environments
Authors: Miyashita Tadashi , Maezono Yasunori , Shimazaki Aya
Published: February 2004

Spiders of the genus Argyrodes are kleptoparasites that steal prey from other web spiders. Recent studies have shown that in addition to stealing prey, they occasionally eat the silk of the host spider webs. How Argyrodes alters the two foraging tactics in the field is still unknown. The foraging behaviour of Argyrodes flavescens was observed in the south‐western part of Japan where prey availability changes greatly with season. Silk‐eating behaviour was commonly observed when insect prey availability on host webs was low, but when prey was abundant, only prey‐stealing behaviour was observed. Spiders spent more time feeding on silk than on prey when prey was scarce. Moreover, in the season when most individuals fed on silk, only a small portion of individuals consumed prey. These results suggest that silk eating is an important alternative foraging tactic under seasonally changing environments.
Use of space and movement patterns in monogamous adult Eurasian beavers (Castor fiber)
Authors: Herr Jan , Rosell Frank
Published: February 2004

Monogamy in mammals is characterized by reduced sexual dimorphism in morphology and behaviour. Ten pairs of Eurasian beaverCastor fiberwere radio‐tracked to test how far this concept can be applied to movement behaviour by focusing on sex‐related effects on territory sizes and movement patterns. Within monogamous pairs, males and females occupied territories of almost equal size during the whole radio‐tracking period and more specifically after parturition. The territories of pair members overlapped on average by 81.6±14.0%sdwhile the territory overlap between residents and their neighbours was small to non‐existent (on average between 0.5% and 2.2%). Males had larger 95% utility distributions than did females during the whole tracking period and after parturition. There was no significant difference between the 50% utility distributions for both sexes. Furthermore, males and females spent equal proportions of their time in territory border zones. There was a non‐significant trend for males to move greater distances at night than females. Nightly distance moved correlated positively with territory size in females but not in males. Nightly distance moved correlated with neither body weight nor colony size. These results suggest that beavers show reduced sexual dimorphism in space use and movement patterns within adult monogamous pairs.
Body temperature and above‐ground patterns during hibernation in European hamsters (Cricetus cricetus L.)
Authors: Wassmer Thomas
Published: February 2004

The purpose of this study was to determine whether hibernating European hamsters Cricetus cricetus, L., 1758 stay in their burrows all winter or if they occasionally spent time above ground. If ‘time (spent) above ground’ (TAG) occurred regularly throughout hibernation, the second objective of this work was to categorize and quantify the patterns of TAG during winter. For this purpose, 11 European hamsters were individually housed in wire mesh cages that were buried in the ground of an outdoor enclosure. Each cage was filled with soil up to ground level allowing the animals to construct their own burrows within the cages. Antennae in the bottom and top of the cage were calibrated to receive signals only when the hamsters were in their burrows or above the ground, respectively. This method enabled continuous recordings of the animal's TAG and provided ecologically meaningful results as the animals were housed in a way that closely resembled their natural habitat. About half of the hamsters stayed continuously below ground. Of these hamsters, almost all showed a dense pattern of episodes of reduced body temperature separated by only brief periods of normothermia. In contrast, the other half of the animals moved either episodically or even regularly above ground. For all of these hamsters, TAG was significantly reduced as compared to normothermic values. One hamster did not show any hibernation but did have a significantly reduced normothermic body temperature and did not leave its burrow for periods of up to 3 weeks.
Acoustic signals in cicada courtship behaviour (order Hemiptera, genus Tibicina)
Authors: Sueur Jérôme , Aubin Thierry
Published: February 2004

During pair formation, cicadas produce acoustic signals that allow sexual partners to meet. The male is generally the emitter, producing calling songs at long range and courtship songs at short range, and the female generally the receiver. The male–female courtship behaviour of seven taxa belonging to the Palaearctic genus Tibicina is described here for the first time. Male courtship songs consisted of a succession of groups of pulses arranged in two sub‐groups. They were short in duration with strong amplitude variations. In all taxa, courtship songs were preceded by a series of 1–5 audible wing‐flicks. Differences in courtship song structure between two pairs of sympatric species, respectively T. corsica corsica/T. nigronervosa and T. corsica fairmairei/T. tomentosa, suggest that courtship signals could act as distinctive species mating recognition systems. In response to male acoustic signalling, females of T. c. corsica, T. c. fairmairei and T. nigronervosa produced audible wing‐flicks such that both sexes established an acoustic duet ending in physical contact. In addition, males and females of T. tomentosa produced silent wing‐flicks, a previously unknown behaviour, which could facilitate pheromone diffusion. Females did not exhibit a species‐specific temporal pattern in acoustic reply to male courtship song and female wing‐flick behaviour does not seem necessary for pair formation. Nevertheless, this strategy through male and female signalling ensured a reciprocal phonotactic approach that probably enhanced the likelihood for the two sexes to meet in complex habitats.
Plans, planners and city images: place promotion and civic boosterism in British reconstruction planning
Authors: LARKHAM PETER J. , LILLEY KEITH D.
Published: February 2004

This article reviews an unusual and subtle form of place promotion, that contained in the series of British post-war reconstruction plans produced up to c. 1952. These were not explicitly designed as place-promotional literature, and we suggest that they should be seen as subverse promotion of towns and cities, as well as vehicles for civic boosterism. Evidence of this is discussed with respect to the production of these plans, for example in the commissioning of eminent and expensive consultants; in the texts of plans; and in the often striking and colourful imagery used.
Glasgow's going round and round: some recent Scottish urban history
Authors: CAMERON EWEN A.
Published: February 2004

If a rural historian who has few credentials to undertake the current review may begin this essay with a point from his own field of research: there is a view of Scottish rural history which argues that far too much attention has been paid to the Highlands. A similar view could be advanced about concentration on Glasgow in Scottish urban history; in addition to the volumes under consideration have been numerous other recent titles. As Professor Morris has noted in a recent review article in this journal, however, other Scottish cities, especially Aberdeen and Dundee, have recently been subjected to variants of the ‘urban biography’ approach. Aberdeen, in particular, has come under intense scrutiny with a two-volume history sponsored by the local authority and taking advantage of the rich resources of the city archives. Edinburgh, by contrast, and notwithstanding the recent culmination of Professor Rodger's extensive researches, remains the poor relation of Scottish urban history: aside from the classic account of the creation of the New Town by A.J. Youngson and the late R.Q. Gray's account of nineteenth-century social history, the existing historiography of Scotland's capital city remains interred in the pages of unpublished theses and scholarly journals.
Current trends in nineteenth- and twentieth-century Spanish urban history
Authors: WALTON JOHN K.
Published: February 2004

It is now several years since José Luis Oyón presented an overview of recent trends in Spanish urban history, and this article seeks to communicate a sense of developments in the field since the mid-1990s, dealing with publications covering the nineteenth and twentieth centuries: ‘contemporary’ rather than ‘modern’ history, in Spanish terminology. The question of what constitutes ‘urban history’ in Spain remains problematic, in the absence of a ‘Dyos phenomenon’, a distinctive urban history teaching enterprise and a sustained and successful dedicated journal. Four annual issues of Historia Urbana, a ‘review of the history of ideas and of urban transformations’, appeared in the mid-1990s, but the final one dates from 1997, and most of the articles presented general theoretical perspectives or articles based on research in countries other than Spain. As Beascoechea and Novo have recently remarked, it seemed in the early 1990s that urban history (or, as they put it, ‘the history of the city’) was becoming established as a recognized discipline in Spain, but subsequent developments have failed to match the expectations that were aroused. Their themed urban history issue of Historia Contemporánea, produced in 2002, is aimed at regaining the lost momentum. Meanwhile, librarians still do not respond to ‘historia urbana’ as a category, seeking to redefine it as ‘urbanismo’, a narrower concept focused on town planning and urban design.
Industry watch
Authors: DALE ROBERT
Published: February 2004

If you wanted to make some money out of natural language processing, an appropriate strategy might be to identify an area of technology that was relatively mature—one where the more fundamental technical problems had been resolved through a significant amount of research activity—and then identify potential applications for that technology.
The Religious and Cultural Roles of Dreams and Visions in Islam
Authors: Green Nile
Published: February 2004

Since “visions appear material to spiritual persons only, the vulgar herd of historians and annalists cannot hope to be so favoured by Heaven”. So, in his nineteenth-century account of the sūfīs of Sind, Sir Richard Burton expressed the dilemma of scholars researching Muslim dream and visionary experiences in his characteristic style. But while scholarly discussion of the visionary activities of premodern sūfīs and other Muslims is still no straightforward matter we need no longer be deterred by Burton's sardonic pessimism. Despite the reticence of earlier generations of positivist scholarship, the past two decades have witnessed a flourishing of research into the visionary aspects of Muslim religious and cultural practice, chiefly through the analysis of the extensive literature surrounding the dream and vision in Islam. For, from the very beginning of Islamic history, there has developed a rich and varied discourse on the nature of the imagination and its expression in the form of dreams and waking visions. The theoretical approaches to the imagination developed by early Muslim philosophers and mystical theorists were always accompanied by the activities of a more active sodality of dreamers and vision seekers. For this reason, Islamic tradition is especially rich for its contributions to both theories of the imagination and the description of its expression in dream and visionary experience. The abundant yields from this rich research field in recent years afford new insight into the Muslim past, allowing an often intimate encounter with past individuals and private experiences scarcely granted by the analysis of other kinds of documentation.
Professor Annemarie Schimmel (April 7, 1922 to January 26, 2003)
Authors: Waghmar Burzine K.
Published: February 2004

Annemarie Brigitte Schimmel, who died aged 80 on 26th January 2003, was the West's most outstanding expert on Sufism, classical and folk Islamic poetry, Indo-Pakistani literature, and calligraphy.
Anniversary General Meeting of the Royal Asiatic Society, Thursday 8 May 2003
Authors: Stockwell A. J.
Published: February 2004

I should like to start by thanking the Honorary Treasurer for presenting his report for 2002. This time last year he likened 2001 to an annus horribilis and this year has been no better for the financial markets. Notwithstanding world crisis and depression, however, the Society's performance, as the Honorary Treasurer has pointed out, has borne comparison with appropriate benchmarks. I congratulate the Honorary Treasurer on his judicious management of the Society's finances. We have also benefited immensely from the wisdom and experience of the other members of the Finance Committee and Investment Sub-Committee.
Suizidalität in Kindheit und Jugend - Einführung in den Themenschwerpunkt
Authors: Becker Katja
Published: February 2004

Zusammenfassung. Vom Thema Suizid im Jugendalter sind neben Kinder- und Jugendpsychiatern auch Ärzte anderer Fachrichtungen betroffen. Vermeidbare Fehler in der medizinischen Erstversorgung parasuizidaler Kinder und Jugendlicher sind z. B. eine unzureichende Abklärung der Suizidalität oder eine zu späte oder ausbleibende Anforderung eines psychiatrischen Konsiliars. Gerade aber in den ersten Stunden nach einem Parasuizid sind Patienten gegenüber Exploration und Intervention am zugänglichsten. Neben der Optimierung dieser Kooperation ist eine bessere Vernetzung der Helfersysteme notwendig. Eltern, Geschwister, Peers und Lehrer sollten Risikofaktoren und Frühwarnzeichen sowie Anlaufstellen zur Hilfe kennen. Den Medien kommt durch die Berichterstattung über suizidales Verhalten mit der Gefahr der Initiierung von Nachahmungstaten und durch Verbreitung von Informationen über Frühwarnzeichen und Hilfeangebote eine besondere Rolle zu.
Side‐scan sonar along the north wall of the Hess Deep Rift: Processing, texture analysis, and geologic ground truth on an oceanic escarpment
Authors: Hurst Stephen D. , Karson Jeffrey A.
Published: February 2004

Side‐scan sonar data collected along the steep, faulted north wall of the Hess Deep Rift provide images of a cross section of the upper oceanic crust. These data are integrated with ground truth from the submersible Alvin and the Argo II remotely operated vehicle (ROV) to evaluate faulting and mass wasting associated with the opening of the rift and to help trace geologic contacts between widely spaced dives and ROV surveys. Initial shipboard and subsequently processed data show excellent backscatter returns with well‐imaged textures and distinctive patterns corresponding to specific rock units and surficial deposits. Four backscatter textures are widely developed and found to correspond to outcrops of basaltic lavas, outcrops of sheeted dikes and gabbroic rocks, surficial talus and rubble deposits, and pelagic sedimentary material. Using test areas identified by Alvin dives, the side‐scan sonar data were processed to automatically classify the backscatter returns in terms of major rock units. The resultant processed image is used for further manual and computer‐aided classification of the scarp geology. These techniques are evaluated for mapping the geology in rugged terrains similar to the steep walls of Hess Deep Rift.
Adding Gaussian noise to inaccurate digital elevation models improves spatial fidelity of derived drainage networks
Authors: Gatziolis Demetrios , Fried Jeremy S.
Published: February 2004

An economical approach to improving predictions of hydrological models produced highly accurate representations of ephemeral and perennial stream networks. Traditional drainage network extraction from digital elevation models (DEMs) often yields inaccurate and inconsistent results because of elevation errors. Topographic wetness index maps calculated from alternative terrain representations, produced by adding random errors to a DEM of a subwatershed with low relief, were combined to delineate a stream network that matches one produced by more time‐intensive (and costly) differential Global Positioning System (GPS) field methods, particularly with respect to the ephemeral component of the drainage network.
Nitrous oxide emissions following incorporation of improved‐fallow residues in the humid tropics
Authors: Millar N. , Ndufa J. K. , Cadisch G. , Baggs E. M.
Published: February 2004

The rotation of crops with fast‐growing tree, shrub, and herbaceous N2‐fixing legume species (improved fallows) is a central agroforestry technology for soil fertility management in the humid tropics. Maize yields are increased following improved fallows compared with continuous maize cropping or traditional natural‐fallow systems consisting of broadleaved weeds and grasses. However, the effect of these improved‐fallow systems on N availability and N2O emissions following residue application has yet to be determined. Emissions from these systems not only have a detrimental effect on the environment, but are of additional concern in that they represent a potentially significant loss of N and a reduction in N‐use efficiency. Emissions of N2O were measured from improved‐fallow agroforestry systems in western Kenya, being characteristic of agroforestry systems in the humid tropics. Emissions were increased after incorporation of fallow residues and were higher after incorporation of improved‐fallow legume residues (Sesbania sesban, Crotalaria grahamiana, Macroptilium atropurpureum) than natural‐fallow residues (mainly consisting of Digitaria abyssibica, Habiscus cannabinus, Bidens pilosa, Guizotia scabra, Leonotis nepetifolia, Commelina benghalensis). Following incorporation of Sesbania and Macroptilium residues (7.4 t dry matter ha−1; 2.9% N) in a mixed fallow system, 4.1 kg N2O‐N ha−1 was emitted over 84 days. The percentages of N applied emitted as N2O following residue incorporation in these tropical agroforestry systems were of the same magnitude as in temperate agricultural systems. N2O (loge) emissions were positively correlated with residue N content (r = 0.93; P < 0.05), and thus the residue composition, particularly its N content, is an important consideration when proposing management practices to mitigate N2O emissions from these systems.
The 226Ra enrichment in oceanic basalts: Evidence for melt‐cumulate diffusive interaction processes within the oceanic lithosphere
Authors: Saal Alberto E. , Van Orman James A.
Published: February 2004

U‐Th decay chains in young volcanic rocks have become a unique geochemical tool with the potential to constrain the physical processes involved in the generation and transport of magmas. Among the different isotopes of the decay series, the measured disequilibrium between 226Ra and 230Th isotopes in basaltic melts has been a crucial player in the interpretation of the U‐series data as a whole. However, the key assumption proposed in all previous models, that the origin of 226Ra‐230Th disequilibrium in oceanic basalts is only produced during mantle melting processes, has remained largely unchallenged. Here we present an alternative process for the origin of the 226Ra‐230Th disequilibrium in oceanic basalts. We argue that diffusive interaction of magmas with cumulates formed in the oceanic crust beneath mid ocean ridges or oceanic islands may be responsible for the observed 226Ra‐230Th disequilibrium in oceanic basalts. Hence the inferences drawn from (226Ra)/(230Th) activity ratios about mantle melting and melt transport processes beneath mid‐ocean ridges and ocean islands are at best equivocal.
Pluto's kinetic interaction with the solar wind
Authors: Delamere P. A. , Bagenal F.
Published: February 2004

Pluto's interaction with the solar wind is determined by photoionization of escaping neutrals, the spatial extent of which depends on the magnitude of the atmospheric escape, and is characterized as Venus‐like to comet‐like for small to large escape rates. The weak magnetic field at >30 AU means that ion kinetic effects play a crucial role at Pluto given both large ion gyroradii and upstream ion inertial lengths that are comparable to the size of the obstacle (2–4 RP). The nature of this highly kinetic interaction has been studied using a three‐dimensional hybrid code (particle ions, fluid electrons). For small, but plausible, neutral escape rates we find that a bow shock structure forms with considerable upstream asymmetry and the velocity distribution of heated protons in the shock region is characterized as a partial ring beam. The downstream wake is highly structured with a density enhanced “arm” of deflected solar wind protons.
Stable carbon isotope composition of atmospheric methyl bromide
Authors: Bill Markus , Conrad Mark E. , Goldstein Allen H.
Published: February 2004

Methyl bromide (CH3Br) constitutes the largest source of bromine atoms to the stratosphere and plays an important role in stratospheric ozone depletion. However, the CH3Br atmospheric budget remains uncertain. We report the first measurements of stable carbon isotope ratios for atmospheric CH3Br and explore the constraints they provide for the atmospheric budget. The measured δ13C of CH3Br ranged from −44.8‰ to −41.2‰ (mean value −43.1‰, N = 7). This isotopic value is less negative than the anthropogenic source signature (−53.2 to −47.5‰), but is indistinguishable from the only quantified natural source signature (−43.0‰). Based on known source signatures and our atmospheric measurements, we predict that the mean kinetic isotope effect associated with sinks must be small (2–4‰). We further estimate that a total phaseout of anthropogenic sources would likely change the isotopic composition of atmospheric CH3Br by 2–4‰, and that this change would be difficult to detect with current measurement techniques.
Passive and active detection of clouds: Comparisons between MODIS and GLAS observations
Authors: Mahesh Ashwin , Gray Mark A. , Palm Stephen P. , Hart William D. , Spinhirne James D.
Published: February 2004

The Geoscience Laser Altimeter System (GLAS), launched on board the Ice, Cloud and Land Elevation Satellite in January 2003 provides space‐borne laser observations of atmospheric layers. GLAS provides opportunities to validate passive observations of the atmosphere for the first time from space with an active optical instrument. Data from the Moderate Resolution Imaging Spectroradiometers aboard the Terr and Aqua satellites are examined along with GLAS observations of cloud layers. In more than three‐quarters of the cases, MODIS scene identification from spectral radiances agrees with GLAS. Disagreement between the two platforms is most significant over snow‐covered surfaces in the northern hemisphere. Daytime clouds detected by GLAS are also more easily seen in the MODIS data as well, compared to observations made at night. These comparisons illustrate the capabilities of active remote sensing to validate and assess passive measurements, and also to complement them in studies of atmospheric layers.
Tectonic evolution of fault‐bounded continental blocks: Comparison of paleomagnetic and GPS data in the Corinth and Megara basins (Greece)
Authors: Mattei M. , D'Agostino N. , Zananiri I. , Kondopoulou D. , Pavlides S. , Spatharas V.
Published: February 2004

We report on new paleomagnetic and anisotropy of magnetic susceptibility (AMS) data from Plio‐Pleistocene sedimentary units from Corinth and Megara basins (Peloponnesus, Greece). Paleomagnetic results show that Megara basin has undergone vertical axis CW rotation since the Pliocene, while Corinth has rotated CCW during the same period of time. These results indicate that the overall deformation in central Greece has been achieved by complex interactions of mostly rigid, rotating, fault bounded crustal blocks. The comparison of paleomagnetic results and existing GPS data shows that the boundaries of the rigid blocks in central Greece have changed over time, with faulting migrating into the hanging walls, sometimes changing in orientation. The Megara basin belonged to the Beotia‐Locris block in the past but has now been incorporated into the Peloponnesus block, possibly because the faulting in the Gulf of Corinth has propagated both north and east. Paleomagnetic and GPS data from Megara and Corinth basins have significant implications for the deformation style of the continental lithosphere. In areas of distributed deformation the continental lithosphere behaves instantaneously like a small number of rigid blocks with well‐defined boundaries. This means that these boundaries could be detected with only few years of observations with GPS. However, on a larger time interval the block boundaries change with time as the active fault moves. Paleomagnetic studies distinguishing differential rotational domains provide a useful tool to map how block boundaries change with time.
Observational evidence against mountain‐wave generation of ice nuclei as a prerequisite for the formation of three solid nitric acid polar stratospheric clouds observed in the Arctic in early December 1999
Authors: Pagan Kathy L. , Tabazadeh Azadeh , Drdla Katja , Hervig Mark E. , Eckermann Stephen D. , Browell Edward V. , Legg Marion J. , Foschi Patricia G.
Published: February 2004

A number of recently published papers suggest that mountain‐wave activity in the stratosphere, producing ice particles when temperatures drop below the ice frost point, may be the primary source of large NAT particles. In this paper we use measurements from the Advanced Very High Resolution Radiometer (AVHRR) instruments on board the National Oceanic and Atmospheric Administration (NOAA) polar‐orbiting satellites to map out regions of ice clouds produced by stratospheric mountain‐wave activity inside the Arctic vortex. Lidar observations from three DC‐8 flights in early December 1999 show the presence of solid nitric acid (Type Ia or NAT) polar stratospheric clouds (PSCs). By using back trajectories and superimposing the position maps on the AVHRR cloud imagery products, we show that these observed NAT clouds could not have originated at locations of high‐amplitude mountain‐wave activity. We also show that mountain‐wave PSC climatology data and Mountain Wave Forecast Model 2.0 (MWFM‐2) raw hemispheric ray and grid box averaged hemispheric wave temperature amplitude hindcast data from the same time period are in agreement with the AVHRR data. Our results show that ice cloud formation in mountain waves cannot explain how at least three large‐scale NAT clouds were formed in the stratosphere in early December 1999.
Residue 182 influences the second step of protein-tyrosine phosphatase-mediated catalysis
Authors: PEDERSEN Anja K. , GUO Xiao-Ling , MØLLER Karin B. , PETERS Günther H. , ANDERSEN Henrik S. , KASTRUP Jette S. , MORTENSEN Steen B. , IVERSEN Lars F. , ZHANG Zhong-Yin , MØLLER Niels Peter H.
Published: February 2004

Previous enzyme kinetic and structural studies have revealed a critical role for Asp181 (PTP1B numbering) in PTP (protein-tyrosine phosphatase)-mediated catalysis. In the E-P (phosphoenzyme) formation step, Asp181 functions as a general acid, while in the E-P hydrolysis step it acts as a general base. Most of our understanding of the role of Asp181 is derived from studies with the Yersinia PTP and the mammalian PTP1B, and to some extent also TC (T-cell)-PTP and the related PTPα and PTP∊. The neighbouring residue 182 is a phenylalanine in these four mammalian enzymes and a glutamine in Yersinia PTP. Surprisingly, little attention has been paid to the fact that this residue is a histidine in most other mammalian PTPs. Using a reciprocal single-point mutational approach with introduction of His182 in PTP1B and Phe182 in PTPH1, we demonstrate here that His182-PTPs, in comparison with Phe182-PTPs, have significantly decreased kcat values, and to a lesser degree, decreased kcat/Km values. Combined enzyme kinetic, X-ray crystallographic and molecular dynamics studies indicate that the effect of His182 is due to interactions with Asp181 and with Gln262. We conclude that residue 182 can modulate the functionality of both Asp181 and Gln262 and therefore affect the E-P hydrolysis step of PTP-mediated catalysis.
The negative regulator of Gli, Suppressor of fused (Sufu), interacts with SAP18, Galectin3 and other nuclear proteins
Authors: PACES-FESSY Mélanie , BOUCHER Dominique , PETIT Emile , PAUTE-BRIAND Sandrine , BLANCHET-TOURNIER Marie-Françoise
Published: February 2004

Sufu (Suppressor of fused) is a negative regulator of the Hedgehog signal-transduction pathway, interacting directly with the Gli family of transcription factors. However, its function remains poorly understood. In the present study, we determined the expression, tissue distribution and biochemical properties of mSufu (mouse Sufu) protein. We identified several mSufu variants of which some were phosphorylated. A yeast two-hybrid screen with mSufu as bait allowed us to identify several nuclear proteins as potential partners of mSufu. Most of these partners, such as SAP18 (Sin3-associated polypeptide 18), pCIP (p300/CBP-cointegrator protein) and PIAS1 (protein inhibitor of activated signal transduction and activators of transcription 1), are involved in either repression or activation of transcription and two of them, Galectin3 and hnRNPA1 (heterogeneous nuclear ribonucleoprotein A1), have a nuclear function in pre-mRNA splicing. We confirmed the mSufu–SAP18 and mSufu–Galectin3 interactions by independent biochemical assays. Using a cell transfection assay, we also demonstrated that mSufu protein (484 amino acids) is predominantly cytoplasmic but becomes mostly nuclear when a putative nuclear export signal is mutated or after treatment of the cells with leptomycin B. Moreover, mSufu is translocated to the nucleus when co-expressed with SAP18, which is normally found in this compartment. In contrast, Galectin3 is translocated to the cytoplasm when it is co-expressed with mSufu. Our findings indicate that mSufu is a shuttle protein that appears to be extremely versatile in its ability to bind different proteins in both the cytoplasm and nucleus.
Human meprin alpha and beta homo-oligomers: cleavage of basement membrane proteins and sensitivity to metalloprotease inhibitors
Authors: KRUSE Markus-N. , BECKER Christoph , LOTTAZ Daniel , KÖHLER Danny , YIALLOUROS Irene , KRELL Hans-Willi , STERCHI Erwin E. , STÖCKER Walter
Published: February 2004

Meprin is a zinc endopeptidase of the astacin family, which is expressed as a membrane-bound or secreted protein in mammalian epithelial cells, in intestinal leucocytes and in certain cancer cells. There are two types of meprin subunits, α and β, which form disulphide-bonded homo- and hetero-oligomers. Here we report on the cleavage of matrix proteins by hmeprin (human meprin) α and β homo-oligomers, and on the interactions of these enzymes with inhibitors. Despite their completely different cleavage specificities, both hmeprin α and β are able to hydrolyse basement membrane components such as collagen IV, nidogen-1 and fibronectin. However, they are inactive against intact collagen I. Hence the matrix-cleaving activity of hmeprin resembles that of gelatinases rather than collagenases. Hmeprin is inhibited by hydroxamic acid derivatives such as batimastat, galardin and Pro-Leu-Gly-hydroxamate, by TAPI-0 (tumour necrosis factor α protease inhibitor-0) and TAPI-2, and by thiol-based compounds such as captopril. Therapeutic targets for these inhibitors are MMPs (matrix metalloproteases), TACE (tumour necrosis factor α-converting enzyme) and angiotensin-converting enzyme respectively. The most effective inhibitor of hmeprin α in the present study was the naturally occurring hydroxamate actinonin (Ki=20 nM). The marked variance in the cleavage specificities of hmeprin α and β is reflected by their interaction with the TACE inhibitor Ro 32-7315, whose affinity for the β subunit (IC50=1.6 mM) is weaker by three orders of magnitude than that for the α subunit (Ki=1.6 µM). MMP inhibitors such as the pyrimidine-2,4,6-trione derivative Ro 28-2653 that are more specific for gelatinases do not bind to hmeprin, presumably due to the subtle differences in the mode of zinc binding and active-site structure between the astacins and the MMPs.
Metallothionein is crucial for safe intracellular copper storage and cell survival at normal and supra-physiological exposure levels
Authors: TAPIA Lucía , GONZÁLEZ-AGÜERO Mauricio , CISTERNAS Mónica F. , SUAZO Miriam , CAMBIAZO Verónica , UAUY Ricardo , GONZÁLEZ Mauricio
Published: February 2004

MTs (metallothioneins) increase the resistance of cells to exposure to high Cu (copper) levels. Characterization of the MT–Cu complex suggests that MT has an important role in the cellular storage and/or delivery of Cu ions to cuproenzymes. In this work we investigate how these properties contribute to Cu homoeostasis by evaluating the uptake, accumulation and efflux of Cu in wild-type and MT I/II null rat fibroblast cell lines. We also assessed changes in the expression of Cu metabolism-related genes in response to Cu exposure. At sub-physiological Cu levels (0.4 µM), the metal content was not dependent on MT; however, when extracellular Cu was increased to physiological levels (10 µM), MTs were required for the cell's ability to accumulate the metal. The subcellular localization of the accumulated metal in the cytoplasm was MT-dependent. Following supra-physiological Cu exposure (>50 µM), MT null cells had a decreased capacity for Cu storage and an elevated sensitivity to a minor increment in intracellular metal levels, suggesting that intracellular Cu toxicity is due not to the metal content but to the interactions of the metal with cellular components. Moreover, MT null cells failed to show increased levels of mRNAs encoding MT I, SOD1 (superoxide dismutase 1) and Ccs1 (Cu chaperone for SOD) in response to Cu exposure. These results support a role for MT in the storage of Cu in a safe compartment and in sequestering an intracellular excess of Cu in response to supra-physiological Cu exposure. Gene expression analysis suggests the necessity of having MT as part of the signalling pathway that induces gene expression in response to Cu.
Haematopoietic protein tyrosine phosphatase (HePTP) phosphorylation by cAMP-dependent protein kinase in T-cells: dynamics and subcellular location
Authors: NIKA Konstantina , HYUNH Huong , WILLIAMS Scott , PAUL Surojit , BOTTINI Nunzio , TASKÉN Kjetil , LOMBROSO Paul J. , MUSTELIN Tomas
Published: February 2004

The HePTP (haematopoietic protein tyrosine phosphatase) is a negative regulator of the ERK2 (extracellular signal-regulated protein kinase 2) and p38 MAP kinases (mitogen-activated protein kinases) in T-cells. This inhibitory function requires a physical association of HePTP through an N-terminal KIM (kinase-interaction motif) with ERK and p38. We previously reported that PKA (cAMP-dependent protein kinase) phosphorylates Ser-23 within the KIM of HePTP, resulting in dissociation of HePTP from ERK2. Here we follow the phosphorylation of this site in intact T-cells. We find that HePTP is phosphorylated at Ser-23 in resting T-cells and that this phosphorylation increases upon treatment of the cells with agents that elevate intracellular cAMP, such as prostaglandin E2. HePTP phosphorylation occurred at discrete regions at the cell surface. Phosphorylation was reduced by inhibitors of PKA and increased by inhibitors of protein phosphatases PP1 and PP2A, but not by inhibitors of calcineurin. In vitro, PP1 efficiently dephosphorylated HePTP at Ser-23, while PP2A was much less efficient. Activation of PP1 by treatment of the cells with ceramide suppressed Ser-23 phosphorylation, as did transfection of the catalytic subunit of PP1. Phosphorylation at Ser-23 is also increased in a transient manner upon T-cell antigen receptor ligation. In contrast, treatment of cells with phorbol ester had no effect on HePTP phosphorylation at Ser-23. We conclude from these results that HePTP is under continuous control by PKA and a serine-specific phosphatase, probably PP1, in T-cells and that this basal phosphorylation at Ser-23 can rapidly change in response to external stimuli. This, in turn, will affect the ability of HePTP to inhibit the ERK and p38 MAP kinases.
A novel omega3-fatty acid desaturase involved in the biosynthesis of eicosapentaenoic acid
Authors: PEREIRA Suzette L. , HUANG Yung-Sheng , BOBIK Emil G. , KINNEY Anthony J. , STECCA Kevin L. , PACKER Jeremy C. L. , MUKERJI Pradip
Published: February 2004

Long-chain n−3 PUFAs (polyunsaturated fatty acids) such as EPA (eicosapentaenoic acid; 20:5n−3) have important therapeutic and nutritional benefits in humans. In plants, cyanobacteria and nematodes, ω3-desaturases catalyse the formation of these n−3 fatty acids from n−6 fatty acid precursors. Here we describe the isolation and characterization of a gene (sdd17) derived from an EPA-rich fungus, Saprolegnia diclina, that encodes a novel ω3-desaturase. This gene was isolated by PCR amplification of an S. diclina cDNA library using oligonucleotide primers corresponding to conserved regions of known ω3-desaturases. Expression of this gene in Saccharomyces cerevisiae, in the presence of various fatty acid substrates, revealed that the recombinant protein could exclusively desaturate 20-carbon n−6 fatty acid substrates with a distinct preference for ARA (arachidonic acid; 20:4n−6), converting it into EPA. This activity differs from that of the known ω3-desaturases from any organism. Plant and cyanobacterial ω3-desaturases exclusively desaturate 18-carbon n−6 PUFAs, and a Caenorhabditis elegans ω3-desaturase preferentially desaturated 18-carbon PUFAs over 20-carbon substrates, and could not convert ARA into EPA when expressed in yeast. The sdd17-encoded desaturase was also functional in transgenic somatic soya bean embryos, resulting in the production of EPA from exogenously supplied ARA, thus demonstrating its potential for use in the production of EPA in transgenic oilseed crops.
Anthrax lethal factor-cleavage products of MAPK (mitogen-activated protein kinase) kinases exhibit reduced binding to their cognate MAPKs
Authors: BARDWELL A. Jane , ABDOLLAHI Mahsa , BARDWELL Lee
Published: February 2004

Anthrax lethal toxin is the major cause of death in systemic anthrax. Lethal toxin consists of two proteins: protective antigen and LF (lethal factor). Protective antigen binds to a cell-surface receptor and transports LF into the cytosol. LF is a metalloprotease that targets MKKs [MAPK (mitogen-activated protein kinase) kinases]/MEKs [MAPK/ERK (extracellular-signal-regulated kinase) kinases], cleaving them to remove a small N-terminal stretch but leaving the bulk of the protein, including the protein kinase domain, intact. LF-mediated cleavage of MEK1 and MKK6 has been shown to inhibit signalling through their cognate MAPK pathways. However, the precise mechanism by which this proteolytic cleavage inhibits signal transmission has been unclear. Here we show that the C-terminal LF-cleavage products of MEK1, MEK2, MKK3, MKK4, MKK6 and MKK7 are impaired in their ability to bind to their MAPK substrates, suggesting a common mechanism for the LF-induced inhibition of signalling.
Role of YHM1, encoding a mitochondrial carrier protein, in iron distribution of yeast
Authors: LESUISSE Emmanuel , LYVER Elise R. , KNIGHT Simon A. B. , DANCIS Andrew
Published: February 2004

Mitochondrial carrier proteins are a large protein family, consisting of 35 members in Saccharomyces cerevisiae. Members of this protein family have been shown to transport varied substrates from cytoplasm to mitochondria or mitochondria to cytoplasm, although many family members do not have assigned substrates. We speculated whether one or more of these transporters will play a role in iron metabolism. Haploid yeast strains each deleted for a single mitochondrial carrier protein were analysed for alterations in iron homoeostasis. The strain deleted for YHM1 was characterized by increased and misregulated surface ferric reductase and high-affinity ferrous transport activities. Siderophore uptake from different sources was also increased, and these effects were dependent on the AFT1 iron sensor regulator. Mutants of YHM1 converted into rho°, consistent with secondary mitochondrial DNA damage from mitochondrial iron accumulation. In fact, in the Δyhm1 mutant, iron was found to accumulate in mitochondria. The accumulated iron showed decreased availability for haem synthesis, measured in isolated mitochondria using endogenously available metals and added porphyrins. The phenotypes of Δyhm1 mutants indicate a role for this mitochondrial transporter in cellular iron homoeostasis.
Amino acid residue 247 in canine sulphotransferase SULT1D1: a new determinant of substrate selectivity
Authors: TSOI Carrie , WIDERSTEN Mikael , MORGENSTERN Ralf , SWEDMARK Stellan
Published: February 2004

The SULT (sulphotransferase) family plays a critical role in the detoxification and activation of endogenous and exogenous compounds as well as in the regulation of steroid hormone actions and neurotransmitter functions. The structure–activity relationships of the human SULTs have been investigated with focus on the amino acid 146 in hSULT1A3 and its impact on dopamine/PNP (p-nitrophenol) specificity. In the present study, we have generated canine SULT1D1 (cSULT1D1) variants with mutations at amino acid residues in the substrate-binding pocket [A146E (Ala-146→Glu), A146D, A146Q, I86D or D247L]. These mutation sites were chosen with regard to their possible contribution to the marked dopamine/PNP preference of cSULT1D1. After characterization, we found that the overall sulphation efficiencies for the cSULT1D1 A146 and the I86 mutants were strongly decreased for both substrates compared with wild-type cSULT1D1 but the substrate preference was unchanged. In contrast, the D247L mutant was found to be more than 21-fold better at sulphating PNP (120-fold decrease in Km value) but 54-fold less efficient in sulphating dopamine (8-fold increase in Km value) and the preference was switched from dopamine to PNP, indicating the importance of this amino acid in the dopamine/PNP preference in cSULT1D1. Our results show that Asp-247 has a pronounced effect on the substrate specificity of cSULT1D1 and thus we have identified a previously unrecognized contributor to active-site selectivity.
A novel copper site in a cyanobacterial metallochaperone
Authors: BORRELLY Gilles P. M. , BLINDAUER Claudia A. , SCHMID Ralf , BUTLER Clive S. , COOPER Chris E. , HARVEY Ian , SADLER Peter J. , ROBINSON Nigel J.
Published: February 2004

The thylakoid lumen of the cyanobacterium Synechocystis PCC 6803 is supplied with copper via two copper-transporting ATPases and a metallochaperone intermediary. We show that the copper site of this metallochaperone is unusual and consists of two cysteine residues and a histidine imidazole located on structurally dynamic loops. Substitution of this histidine residue enhances bacterial two-hybrid interaction with the cytosolic copper exporter, but not the copper importer, suggesting that the interacting surfaces are distinct, with implications for metal transfer.
Enalapril attenuates cardiorenal damage in nitric-oxide-deficient spontaneously hypertensive rats
Authors: PEREIRA Leila M. M. , BEZERRA Daniele G. , MACHADO Denise L. , MANDARIM-DE-LACERDA Carlos A.
Published: February 2004

Stereological structural alterations of the heart and kidney were studied in four groups (n=5) of spontaneously hypertensive rats (SHRs) treated for 30 days: (i) control, (ii) NG-nitro-L-arginine methyl ester [L-NAME; nitric oxide (NO) synthesis inhibitor] alone, (iii) enalapril alone and (iv) L-NAME plus enalapril. Blood pressure (BP) was elevated significantly in NO-deficient SHRs (rats receiving L-NAME) or significantly lower in enalapril-treated SHRs. Co-administration of L-NAME and enalapril caused a 20% decrease in BP compared with untreated SHRs. NO-deficient SHRs had a decrease in body mass, but this loss of body mass was prevented efficiently in the enalapril-treated group. Enalapril treatment decreased the left ventricular (LV) mass index in SHRs, even in animals with NO synthesis blocked. NO deficiency in SHRs caused a larger decrease in the number of LV cardiomyocyte nuclei, which had a negative correlation with both LV mass index and BP. The volume-weighted glomerular volume (VWGV) separated the SHRs into two groupings: (i) control and NO-deficient SHRs, and (ii) enalapril- and L-NAME plus enalapril-treated SHRs. There was a significant difference between these two groupings, with VWGV being more than 15% smaller in the latter compared with the former grouping. The present findings reinforce the evidence that enalapril efficiently treats genetic hypertension, and demonstrate that this effect is observed even when NO synthesis is inhibited. Enalapril administration also decreases cardiac and renal structural damage caused by genetic hypertension, as well as by the interaction between genetic hypertension and NO deficiency.
Sex steroid receptors in rheumatoid arthritis
Authors: ISHIZUKA Masato , HATORI Masahito , SUZUKI Takashi , MIKI Yasuhiro , DARNEL Andrew D. , TAZAWA Chika , SAWAI Takashi , UZUKI Miwa , TANAKA Yasuhisa , KOKUBUN Shoichi , SASANO Hironobu
Published: February 2004

Rheumatoid arthritis (RA) is a disease characterized primarily by chronic inflammatory synovitis and is well-known to be associated with significant sex differences in its prevalence and clinical features. Sex steroids have been proposed to be involved in the pathogenesis of RA, but details pertaining to the expression of sex steroid receptors in RA synovial tissue have yet to be fully characterized. In the present study, we examined oestrogen receptor (ER) α, ERβ, progesterone receptor (PR) and androgen receptor (AR) mRNA expression using real-time reverse transcriptase–PCR (RT-PCR) in eight female RA synovial tissues and six female synovial tissues without inflammation, and determined immunolocalization of ERα, ERβ, PR-A, PR-B and AR using immunohistochemistry in synovial tissues obtained from 22 RA patients. Real-time RT-PCR analysis demonstrated the expression of ER, PR and AR mRNAs in both RA and non-inflamed synovial tissues. Relative abundance of ER mRNAs was significantly higher in RA synovial tissue than non-inflamed synovial tissue (P<0.05). In addition, the relative ERα/ERβ mRNA expression ratio was significantly lower in RA than non-inflamed synovial tissue (RA, 2.34±1.60; and non-inflamed, 20.7±19.1; P<0.05). There were no significant differences in relative abundance of PR mRNA. Relative abundance of AR mRNA was significantly lower in RA (P<0.05). Immunoreactivity for ERα, ERβ, PR-B and AR was detected in the lining cells, inflammatory cells and fibroblasts in all the patients examined. The labelling indices for ERβ and PR-B were more abundant in both lining cells (ERβ, 54.2±12.2%; PR-B, 73.6±18.9%) and inflammatory cells (ERβ, 74.6±16.2%; PR-B, 75.9±16.1%) than in fibroblasts (ERβ, 36.5±15.6%; PR-B, 49.4±18.0%). Labelling indices for ERα and AR were significantly higher in lining cells (ERα, 14.4±8.6%; AR, 31.2±11.3%) and fibroblasts (ERα, 12.1±7.5%; AR, 20.1±9.6%) than those in inflammatory cells (ERα, 5.7±3.3%; AR, 9.2±4.4%). There were significant differences (P<0.05) in the labelling indices for ERα, ERβ and PR-B between men and women under 50 years of age in fibroblasts of RA synovial tissues. These results indicate that sex steroid receptors are present in RA and non-inflamed synovial tissues, including inflammatory cells in RA, and suggest that sex steroids may play important roles in the regulation of inflammation of RA synovial tissue.