bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transgenic Brassica napus plants overexpressing aluminium‐induced mitochondrial manganese superoxide dismutase cDNA are resistant to aluminium
Authors: Basu U. , Good A. G. , Taylor G. J. 
Published: March 2003

AbstractWe investigated the role that manganese superoxide dismutase (MnSOD, EC 1·15·1·1), an important enzyme of the antioxidant pathway, may play in aluminium (Al) toxicity/resistance. A wheat (Triticum aestivum) cDNA (WMnSOD) was cloned and up‐regulation of the transcript was observed in root tips after 24 h exposure to 100 µm Al. The WMnSOD1 under the control of the CaMV35S promoter was expressed in canola (Brassica napus). Transgenic plants were phenotypically normal. Northern analyses showed enhanced levels of the WMnSOD1 and WMnSOD1‐GUS transcripts and total SOD activity was 1·5‐ to 2·5‐fold greater in transgenic plants than in wild type (WT) plants. Transgenic (T1) leaf discs showed increased retention of chlorophyll and reduced electrolyte leakage when exposed to methyl viologen (MV) as compared with WT leaf discs, suggesting that transgenic plants were more resistant to oxidative stress. When WT canola plants were exposed to aluminium (0–200 µm), inhibition of root growth, higher SOD activity and increased levels of malondialdehyde (MDA, an indicator of lipid peroxidation) were observed in roots. Aluminium‐induced inhibition of root growth and accumulation of MDA was lower in homozygous transgenic plants (T2) compared with WT plants. Transgenic lines also showed lower synthesis of 1,3‐β‐glucans (callose, a sensitive marker for Al injury) as compared with WT. These data suggest that resistance to Al toxicity can be improved by overexpressing WMnSOD1.
Local annual survival of booming male Great Bittern Botaurus stellaris in Britain, in the period 1990–1999
Authors: Gilbert Gillian , Tyler Glen A. , Smith Ken W. 
Published: March 2003

Male Great Bitterns Botaurus stellaris have individually distinctive boom vocalizations which have been used since 1990 to count the British population accurately. We used vocal individuality to identify birds between years and analyse the survival of the British booming population. We used six instances of Great Bitterns known to be the same birds (from radio tracking and re‐sighting of darvic rings) in successive years to provide a means of identification independent from vocalizations. All of these birds remained in the same territory from one year to the next. Seven spectrogram measures were chosen as quantitative descriptors of Great Bittern booms. Boom similarity was expressed in terms of Euclidean ‘acoustic’ distance between descriptors of pairs of birds. Great Bitterns that were known to be the same birds had more similar booms across years than those known to be different. The acoustic distances and knowledge of site fidelity were used to construct parsimonious rules on which to base re‐identification decisions and to build survival histories. Great Bittern local survival in Britain as a whole was estimated as 70% (± 5.1 se) with survival in north‐west England (at Leighton Moss) higher (82.8%, ± 7.3 se) than that in East Anglian sites (65.2%, ± 5.4 se) (χ12 = 3.4, P = 0.07). Movements of males between years were apparent between sites within the Suffolk and Norfolk coastal regions but not on a large scale. Survival of adult males in East Anglia was positively related to winter rainfall, but there was no significant relationship with winter temperature. There was a positive relationship between the annual population change in East Anglia and the annual local adult survival rate.
Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases define the migratory characteristics of human monocyte‐derived dendritic cells
Authors: Osman Mohamed , Tortorella Micky , Londei Marco , Quaratino Sonia 
Published: March 2003

SummaryDendritic cells (DCs) have an essential role in the initiation of immune responses as they deliver antigen/epitope and the appropriate signals to activate naïve T cells and thus start an immune response. In order to fulfil their function, DCs have to patrol different part of the body, thus migrating through the extracellular matrix to sample the local ‘antigenic’ environment. In the present study, we have investigated which enzymes might be involved in this process using the Matrigel trans‐well migration assay, an in vitro model of extracellular matrix migration. In this assay we analysed the migratory ability of interleukin‐4 (IL‐4)/granulocyte macrophage–colony‐stimulating factor (GM‐CSF)‐derived immature DCs as well as mature DCs, induced by tumour necrosis factor‐α (TNF‐α) and modified vaccinia virus Ankara (MVA). The ‘mature’ DCs showed an increased migration through Matrigel, which was significantly inhibited by inhibitors of matrix metalloproteinases (MMP). We also observed that the dominant MMP involved in this process was MMP‐9, and a concomitant decrease of the endogenous tissue inhibitors of metalloproteinases (TIMP)‐1 and TIMP‐2 was also observed. Collectively these data suggest that the balance between MMP/TIMP determines the net migratory capacity of human DCs. Surprisingly, TIMP‐3 was significantly increased in mature DC. Our data thus indicate that MMP and TIMP play a role in the migratory ability of human DCs. Our results also suggest that TIMP‐3 expression might represent a new marker of maturation of human DCs.
Morphometric and immunohistochemical characterization of the intimal layer throughout the arterial system of elderly humans
Authors: Vink Aryan , Schoneveld Arjan H. , Poppen Marieke , De Kleijn Dominique P. V. , Borst Cornelius , Pasterkamp Gerard 
Published: March 2003

AbstractThe purpose of the present study was to obtain insight into the natural development of adaptive intimal thickening and atherosclerosis in the arterial tree of human species. The morphometry and composition of the intimal layer were studied in the arterial system of elderly individuals. Post mortem, a total of 703 arterial segments were dissected from 24 subjects (age 81.9 ± 9.9 years). From each subject, segments were dissected from 31 different arteries. Area stenosis [(plaque area/vessel area) × 100%] was determined in each segment. By (immuno)histochemistry, lipid content and the presence of inflammatory cells (macrophages) were assessed in the coronary, common carotid, brachial, radial and internal iliac arteries. Adaptive intimal thickening or advanced atherosclerosis was observed in all studied artery types. Area stenosis was highest in the coronary arteries (median, 30%) and lowest in the arteries supplying the brain (median, ≤ 7%). Plaques hiding a lipid‐rich core and plaques with macrophage infiltration were observed in all five selected artery types. In summary, the present observation demonstrates that intimal thickening is a systemic process involving most artery types. Within elderly humans, features of advanced atherosclerotic disease, a lipid‐rich core and macrophages, can be observed in the intimal layer of artery types that are recognised for their relation with clinical syndroms as well as artery types that remain clinically silent.
Behavioural factors affecting foraging effort of breeding wandering albatrosses
Authors: Shaffer Scott A. , Costa Daniel P. , Weimerskirch Henri 
Published: March 2003

Summary

The study examined the behavioural factors that influence variation in foraging costs of wandering albatrosses (Diomedea exulans Linnaeus) during two consecutive years. This was performed by measuring simultaneously foraging activities and metabolic rates (W kg−1) of breeding birds during the incubation periods of 1998 and 1999.
A total of 38 birds (19 in each year) were injected with doubly labelled water, equipped with satellite transmitters to measure foraging distance and flight speed, and equipped with activity recorders to measure landings and take‐offs from the water surface.
In 1999, birds spent on average 30% more time at sea (11·07 ± 3·53 SD, days), travelled 43% further (5473 ± 2348 SD, km) and increased the number of landings and take‐offs per day by 66% (28·1 ± 11·4 SD, landings per day) compared to 1998.
Energy expenditure rates during foraging were significantly higher in 1999 (5·3 ± 0·8 SD, W kg−1, n = 8) compared to 1998 (4·5 ± 0·5 SD, W kg−1, n = 11).
Landing and take‐off rates explained the greatest proportion of variation in energy expenditure rates of wandering albatrosses, rather than total distance travelled, flight speed or time in flight.
Despite 18% higher foraging costs in 1999, the daily rate of food intake was similar between years, suggesting that energy acquisition per unit effort was lower.
The energetic cost of flight for wandering albatrosses was estimated to fall between 3·4 and 5·1 W kg−1, or 1·4–2·0 × measured BMR, one of the lowest flight cost yet reported for any seabird.
Do female coleopteran parasitoids enhance their reproductive success by selecting high‐quality oviposition sites?
Authors: Fournet S. , Poinsot D. , Brunel E. , Nénon J. P. , Cortesero A. M. 
Published: March 2003

Summary

Female parasitoids that lay their eggs away from potential host insects are supposed to have only a minor influence on the fitness of their own progeny, as they do not select and evaluate directly the quality of hosts for their offspring. Aleochara bilineata Gyll. (Coleoptera: Staphylinidae) females oviposit near to cabbage plants infested by larvae of Delia radicum L. (Diptera: Anthomyiidae). Once the mobile A. bilineata larva emerges from the egg, it must then search the soil to find and select a suitable fly pupa. The beetle larvae have a limited time to found pupae and can only parasitize one host pupa during their lifetime. Moreover, because A. bilineata is a solitary parasitoid whether or not the host pupa is parasitized, has a strong influence on the successful development of the beetle larva.
We studied the oviposition behaviour of A. bilineata females in laboratory experiments in which females could choose between a range of several oviposition sites.
Our results reveal that A. bilineata females, like hymenopteran parasitoid females, show an adaptive oviposition behaviour in response to the quality of the oviposition site. The female beetles adapt their oviposition decisions and their clutch size based on information associated with the presence of a host. Furthermore, our results reveal that the Aleochara females can discriminate between specific cues related to the stage and parasitization status of the host. Such behaviours may greatly enhance the parasitization success of the larvae, and thereby female fitness.
Ecology of fruit‐colour polymorphism in Myrtus communis and differential effects of birds and mammals on seed germination and seedling growth
Authors: Traveset Anna , Riera Núria , Mas Rafael E. 
Published: March 2003

Summary

The fruit‐colour polymorphism of Myrtus communis, a common Mediterranean shrub, is examined. We investigate whether frugivores affect the maintenance of the polymorphism, whether morphs differ in germination or seedling growth, and whether passage through frugivores’ gut affects seed behaviour and seedling growth.
Blue berries are very similar in morphological traits and nutrient composition to the rarer white morph. Rates of fruit removal by birds, the main dispersers of this species, did not differ between morphs, suggesting that a colour preference is not involved in maintenance of the polymorphism.
Seeds of the two morphs showed the same germinability (final percentage germination) as well as similar rates of germination under controlled conditions (in growth chamber and greenhouse). Outdoors, seeds from blue berries tended to germinate slightly faster (which might give them an early advantage) but differences between morphs disappeared after several weeks of growth.
The germination of myrtle seeds is differently affected by passage through the digestive tract of birds, which appeared to significantly increase germinability, and of the carnivorous pine marten, Martes martes, which did not. The different seed retention time in the gut or the chemical composition of the food ingested along with the seeds may be responsible for such differences.
The detection of a positive effect of bird ingestion in outdoor conditions, but not in the growth chamber or in the greenhouse, demonstrates the importance of performing germination tests in the natural habitat.
Seed size, irrespective of morph, affects the response to passage through the bird gut. Large seeds, which are more rapidly ejected, and are thus less abraded, germinated at a similar speed to non‐ingested controls. Variation in seed size within a single species should thus be considered in future studies.
Abrupt vegetation changes in the Segura Mountains of southern Spain throughout the Holocene
Authors: Carrión J. S. , Munuera M. , Dupré M. , Andrade A. 
Published: March 2003

Summary

The fossil pollen record of Cañada de la Cruz in the Segura mountains of southern Spain yields insights into high‐elevation vegetational dynamics over the last c. 8320 years. Phases of xerophytic grassland alternate with high‐mountain open pine forests and expansion of deciduous forests and Mediterranean scrub at lower altitudes.
Longer‐term stable vegetation patterns are interrupted by multidecadal to century‐scale shifts at about 7770, 3370, 2630, 1525 and 790 years BP.
Some of the vegetation types have no modern analogues and represent high‐altitude remnants of widespread last‐glacial xerophytic communities. Other species patterns, characteristic of current scrub associations, appeared only within the last 800 years.
The sequence fits within the regional context of a generally wet mid‐Holocene (c. 7700–3300 years BP) characterized by spread of mesophilous vegetation, between drier conditions characterized by greater abundance of xerophytes.
The pollen record and current ecological studies on high‐elevation vegetation of Mediterranean Spain suggest that control of vegetation is primarily climatic although grazing pressure, which would have pushed vegetation over a threshold for change, cannot be discounted.
Forest canopy and community dynamics in a temperate old‐growth evergreen broad‐leaved forest, south‐western Japan: a 7‐year study of a 4‐ha plot
Authors: Miura Masahiro , Manabe Tohru , Nishimura Naoyuki , Yamamoto Shin‐ichi 
Published: March 2003

Summary

Forest canopy gap and community dynamics were studied in a 4‐ha permanent plot of an old‐growth evergreen broad‐leaved forest dominated by Castanopsis cuspidata var. sieboldii and Distylium racemosum in the Tatera Forest Reserve, Tsushima Islands, south‐western Japan. The forest was affected by a powerful typhoon in 1987 and was monitored from 1990 to 1997.
In 1990, all woody stems ≥ 5 cm diameter at breast height (d.b.h.) in the plot were identified, mapped and marked, and the state of 1600 5 m × 5 m contiguous quadrats used to locate canopy gaps. Gaps occupied 17.1% of the plot, which contained 4494 tree and shrub stems (total basal area 63.48 m2 ha−1). Gaps were re‐censused in 1997 and both marked and newly recruited (≥ 5 cm d.b.h.) stems were recorded in 1992 and 1997.
Over 7 years the rates of canopy gap formation and closure were 0.72% year−1 and 1.61% year−1, respectively, mortality and recruitment rates were 0.97% year−1 and 0.99% year−1, and the rates of loss and gain in basal area were 0.95% year−1 and 0.83% year−1.
The mortality of stems was size‐dependent, with those in middle size classes having the lowest rates. Mortality of stems was lower in canopy and higher in the understorey, while the proportion of stems killed by disturbances increased with height.
Stems that died during the 7 years were predominantly located in newly created gaps, whereas stems were recruited into both established and new gaps. Deciduous broad‐leaved species were largely restricted to gaps that remained open throughout the study.
Both composition and structure of the forest changed in response to disturbance‐related effects on canopy dynamics.
Rapid recent range‐margin rise of tree and shrub species in the Swedish Scandes
Authors: Kullman Leif 
Published: March 2003

SummaryRecent elevational range‐margin performance of tree and shrub species was studied at a site in the Swedish Scandes. The methods included comparisons of historical and present‐day range‐margin records (m a.s.l.) in conjunction with age‐determination of newly established saplings.Since the early 1950s, the range‐margins ofBetula pubescensssp.tortuosa(mountain birch),Picea abies(Norway spruce),Pinus sylvestris(Scots pine),Sorbus aucuparia(rowan) andSalixspp. (willows) have advanced by 120–375 m to colonize moderate snow‐bed communities. The non‐nativeAcer platanoides(Norway maple) has become established just below the birch forest‐limit. In concert with tree‐limit rises by 100–150 m in the same region, the present results suggest a shift in reproduction and a significant break in the late‐Holocene vegetation history.Ring‐counting (in 2000) of a subsample of the recovered saplings revealed that, with one exception, they were aged between 7 and 12 years, i.e. they germinated after 1987. Since 1988 there has been strong and consistent winter warming, with some very warm summers, and this may ultimately have forced the vegetational changes.Reduced summer snow‐retention has favoured seedling establishment and juvenile growth, and mild winters, with reduced risk of frost‐desiccation, have enhanced survivorship and height increment.Certain seed‐regenerating tree and shrub species have tracked recent climate change quite rapidly and more sensitively than vegetatively propagating field‐layer species. Such species‐specific responses may give rise to novel high‐elevation vegetational patterns in a hypothetically warmer future world.
Measurement of the three‐dimensional microscope point spread function using a Shack–Hartmann wavefront sensor
Authors: Beverage J. L. , Shack R. V. , Descour M. R. 
Published: March 2003

SummaryWe present a technique to measure the wavefront in the exit pupil of a microscope to determine the microscope’s three‐dimensional point spread function (PSF) experimentally. The wavefront yields the microscope PSF through a Fourier transform that models propagation of light from the exit pupil to the image plane. A Shack–Hartmann wavefront sensor is used to measure the wavefront shape by recording lateral displacements of a grid of focused spots created by a lenslet array. The displacement of each spot is related to the local wavefront slope. Thus, with appropriate sampling across the exit pupil, the entire wavefront can be reconstructed. This technique does not require the use of a sub‐resolution object to obtain the three‐dimensional microscope PSF. Consequently, larger, brighter fluorescent objects may be imaged, thereby reducing the requirements for detector sensitivity and leading to a three‐fold increase in the axial range over which the PSF is measured. The Shack–Hartmann technique results in a description of the PSF as a continuous function whose sampling is not dependent on the size of the CCD pixels. The Shack–Hartmann sensor is not limited by the numerical aperture of the objective and can easily be calibrated to measure the PSF at any wavelength.
Study of carbon fibres and carbon–carbon composites by scanning thermal microscopy
Authors: Blanco C. , Appleyard S. P. , Rand B. 
Published: March 2003

SummaryScanning thermal microscopy (SThM) is a relatively new technique based on atomic force microscopy in which the tip is replaced by an ultra‐miniature temperature probe. This paper reports on a preliminary investigation of the application of SThM in the characterization of the thermal properties of carbon fibres and carbon–carbon (CC) composites. The technique enabled a comparative study to be made of discrete fibre and matrix thermal properties in a series of model unidirectional composites. The thermal images revealed a marked increase in thermal conductivity of the matrix with increasing temperature of treatment and hence confirmed the development of a highly ordered carbon matrix. The results were in qualitative agreement with previously determined values of thermal conductivity from which the separate values of fibre and matrix thermal conductivity had been derived. The technique was also applied to the characterization of samples of unknown processing history, enabling an estimation to be made of the heat treatment and type of the fibres and matrix present in the composite. It was concluded that SThM promises to be a powerful technique for the study of the thermal properties of CC composites and carbon fibres, as it uniquely enables variations in local thermal conductivity to be detected and resolved. Absolute quantification of the technique remains the key to its future widespread acceptance in materials characterization.
Phase evolution in cholesterol/DPPC monolayers: atomic force microscopy and near field scanning optical microscopy studies
Authors: Yuan C. , Johnston L. J. 
Published: March 2003

SummaryA combination of atomic force microscopy (AFM) and near field scanning optical microscopy has been used to study domain formation in dipalmitoylphosphatidylcholine (DPPC)/cholesterol monolayers with cholesterol concentrations ranging from 0 to 50%. The results show a clear evolution from a mixture of liquid expanded and liquid condensed phases for cholesterol concentrations < 10% to a mixture of liquid expanded and two cholesterol‐containing phases at intermediate concentrations, and finally to a single homogeneous liquid ordered phase for 33% cholesterol. Mixtures of the various phases are clearly identified by height differences in AFM and in some cases by fluorescence imaging for samples containing 0.5% BODIPY dye, which localizes preferentially in the more fluid phase. Note that fluorescence imaging, at least with the dye used here, is unable to distinguish between the cholesterol‐rich and cholesterol‐poor phases detected at intermediate cholesterol concentrations. The combination of fluorescence and AFM imaging provides a more complete picture of the phase evolution for cholesterol/DPPC monolayers than could be obtained by either technique alone, and presents substantial advantages over conventional fluorescence microscopy in that submicrometre‐sized domains can be readily detected.
Functional expression of corticotropin‐releasing hormone (CRH) receptor 1 in cultured rat microglia
Authors: Wang Wei , Ji Ping , Riopelle Richard J. , Dow Kimberly E. 
Published: March 2003

AbstractCorticotropin‐releasing hormone (CRH), known as a key regulator of the hypothalamic–pituitary–adrenal axis response to stress, elicits its biological effects by binding to two membrane receptors (CRH‐R1 and CRH‐R2). The present studies examined the presence of functional expression of CRH receptors in cultured microglia of rat. CRH‐R1 mRNA and protein were detected by reverse transcriptase polymerase chain reaction (RT‐PCR), western blotting and receptor chemical cross‐linking assay in cultured microglia. CRH‐R2 mRNA was undectable by RT‐PCR. The radioligand binding analysis using [125I]Tyr‐rat/human CRH revealed a high affinity binding site (Kd of 1.2 nm and Bmax of 84 fmol/mg of protein). Competition studies using CRH and related peptides indicated kinetic and pharmacological characteristics consistent with the CRH‐R1 receptor subtype. Receptor chemical cross‐linking assay demonstrated a single band of CRH receptor with a molecular weight of ∼77 kDa, which was inhibited in the presence of excess unlabeled rat/human CRH in a dose‐dependent manner and inhibited by a CRH receptor␣antagonist astressin. Functional coupled cAMP production in cultured microglia was stimulated by exogenous addition of CRH and related peptides in a dose‐dependent manner and blocked by astressin. Our findings suggest the functional expression of CRH‐R1 receptor in rat microglia, indicating an important mechanism of interaction between immune and neuroendocrine systems in brain physiological and␣pathological conditions.