bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental investigation of oxygen isotope exchange between CO2 and O(1D) and its relevance to the stratosphere
Authors: Chakraborty Subrata , Bhattacharya S. K.
Published: December 2003

Stratospheric CO2 is found to be enriched in heavy oxygen isotopes relative to tropospheric CO2 values caused by photo‐induced isotopic exchange with stratospheric ozone, a gas highly enriched in heavy isotopes relative to the ambient oxygen. The transfer of isotopic enrichment from the ozone pool to the CO2 pool takes place through CO*3 formed by reaction of CO2 with O(1D) derived from O3 photolysis. Recent stratospheric measurements indicate that the transfer process results in CO2 getting more enriched in 17O compared to 18O. Experiments, reported here, investigate this exchange and determine the effects of the initial isotopic composition of CO2 and O3 on the final isotopic composition of the exchanged CO2. It is seen that the slope relating 17O and 18O enrichments in CO2 depends on the initial isotopic composition of the two gases. Interestingly, with CO2 of tropospheric composition and O3 of stratospheric composition the observed slope (1.82 ± 0.04) is close to the value (1.71) found for stratospheric CO2. The apparent extra 17O enrichment in CO2 resulting in slope higher than that of O3 can be explained by simple mixing if one assumes that O(1D) originates mainly from the asymmetric ozone species and if additional fractionation occurs because of differences in collision frequencies of isotopic species and possibly also during dissociation of CO*3 to CO2 and O atom.
Multiobjective calibration of land surface model evapotranspiration predictions using streamflow observations and spaceborne surface radiometric temperature retrievals
Authors: Crow W. T. , Wood E. F. , Pan M.
Published: December 2003

Physically based models of surface water and energy balance processes typically require a large number of soil and vegetation parameters as inputs. Accurate specification of these parameters is often difficult without resorting to calibration of model predictions against independent observations. Along with streamflow observations from gauging stations, spaceborne surface radiometric temperature retrievals offer the only independent observation of land surface model output commonly available at regional spatial scales (i.e., >502 km2). This analysis examines the potential benefits of incorporating spaceborne radiometric surface temperature retrievals and streamflow observations in a multiobjective calibration framework to accurately constrain regional‐scale model evapotranspiration predictions. Results for the VIC (Variable Infiltration Capacity) model over the Southern Great Plains of the United States suggest that multiobjective model calibration against radiometric skin temperatures and steamflow observations can reduce error in model monthly evapotranspiration predictions by up to 20% relative to single‐objective model calibration against streamflow alone.
Late Holocene variability of upper North Atlantic Deep Water temperature and salinity
Authors: Marchitto Thomas M. , deMenocal Peter B.
Published: December 2003

Magnesium/calcium ratios in benthic foraminifera (Cibicidoides pachyderma) from a sediment core on the Laurentian Slope (1854 m) exhibit strong millennial‐scale fluctuations during the past 4000 years. We convert these data to seawater paleotemperatures using a new monospecific linear equation. Results suggest that the temperature of upper North Atlantic Deep Water (dominated by Labrador Seawater today) has varied by at least 2°C during the late Holocene. Millennial scale coolings coincide with previously identified periods of increased drift ice and regional glacier advances, including the Little Ice Age. Paired oxygen isotope measurements indicate that salinity and perhaps density were reduced during the cold periods. We discuss possible mechanisms for transmitting this cold, fresh signal from surface waters to intermediate depths. Our reconstructed late Holocene ranges in upper North Atlantic Deep Water properties greatly exceed those of the instrumental record and imply that large changes may be yet to come.
Very early chlorine activation and ozone loss in the Arctic winter 2002–2003
Authors: Tilmes Simone , Müller Rolf , Grooß Jens‐Uwe , Höpfner Michael , Toon Geoffrey C. , Russell James M.
Published: December 2003

Chlorine activation and chemical ozone destruction is investigated in the Arctic winter 2002–03 using the tracer‐tracer correlation technique. Consistent with very low temperatures in the early vortex, strong chlorine activation at 520 K potential temperature was observed already in mid‐December 2002 by the MkIV balloon and at 400–500 K in early January 2003 from HALOE satellite measurements. Large column ozone loss was derived inside the outer vortex in January (23 ± 9 DU) and substantially greater losses in February (51 ± 9 DU) inside the vortex core in 380–550 K. Calculated ozone loss is similar in February in the two completely separated parts of the vortex. Little influence of mixing in of mid‐latitude is noticeable after the reunification of the vortex. Further, some ozone loss at lower altitudes likely occurred during March and April consistent with polar stratospheric clouds detected by MIPAS‐ENVISAT towards the end of March.
A new explanation of persistent double meteor trains
Authors: Kelley M. C. , Kruschwitz C. , Drummond J. , Gardner C. , Gelinas L. , Hecht J. , Murad E. , Collins S.
Published: December 2003

Persistent meteor trains, studied for more than a century, remain somewhat mysterious [Newton, 1869; Trowbridge, 1907; Chapman, 1955; Hapgood, 1980]. The Leonids meteor showers of recent years afforded opportunities to apply new research technologies, including lidars and sophisticated cameras. Here we explore a particularly curious but common feature: double trains. Since the traditional hollow cylinder explanation has been shown to be untenable, we suggest a new explanation, arguing that one train is due to gaseous vapor train emissions behind the meteor while the other is due to heterogeneous chemistry associated with recoagulated dust. In this model the separation is caused by gravitational sedimentation of dust particles, an idea supported by rocket‐based observations of recoagulated dust behind a meteor, by rocket‐based observations of enhanced sodium emissions in a dust layer, by rocket observations of a dusty trail, and by recent theoretical estimates of chemical reactions on dust.
Cluster four spacecraft measurements of small traveling compression regions in the near‐tail
Authors: Slavin J. A. , Owen C. J. , Dunlop M. W. , Borälv E. , Moldwin M. B. , Sibeck D. G. , Tanskanen E. , Goldstein M. L. , Fazakerley A. , Balogh A. , Lucek E. , Richter I. , Reme H. , Bosqued J. M.
Published: December 2003

Cluster observations taken during a substorm on September 19, 2001 have revealed the presence of small traveling compression regions (TCRs) in the near tail. These measurements are used to determine directly the speed and direction of TCR propagation and the amplitude of the underlying bulge in the plasma sheet. The time‐of‐flight speeds derived from the arrival times of the magnetic perturbations at the different Cluster s/c yielded a mean speed of 413 km/s. For 2 of the TCRs s/c 1, 2 and 4 were located sufficiently close to the plasma sheet that they were immersed in the central plasma sheet plasma as the TCR swept over s/c 3. In this manner the Cluster measurements directly demonstrated that these small TCRs are caused by moving bulges in the plasma sheet‐lobe interface. In summary, our analysis of the Cluster measurements has directly demonstrated the existence of moving bulges in the north‐south thickness of the plasma sheet, most probably due to the formation of flux ropes, and their role in producing traveling compression regions.
Forecasting summer rainfall over India using genetic algorithm
Authors: Kishtawal C. M. , Basu Sujit , Patadia Falguni , Thapliyal P. K.
Published: December 2003

In this study we have assessed the feasibility of a nonlinear technique based on genetic algorithm for the prediction of summer rainfall over India. The genetic algorithm finds the equations that best describe the temporal variations of the seasonal rainfall over India, and therefore enables the forecasting of the future rainfall. The forecast equation developed in the present study uses the monthly mean rainfall during June, July, and August for past years over five rainfall homogeneous zones of India to predict the seasonal rainfall (JJA combined) over the Indian landmass.
Salt‐finger driven enhancement of upper ocean nutrient supply
Authors: Oschlies A. , Dietze H. , Kähler P.
Published: December 2003

In the subtropics, estimates of upper‐ocean nitrate supply by turbulent mixing have been found insufficent to balance estimated nutrient loss through organic‐matter export. Most mixing‐rate estimates as well as numerical turbulence closure schemes commonly employed in numerical models have, however, neglected salt‐finger induced mixing. Here we examine the potential contribution of salt‐finger induced mixing to nutrient fluxes. Our model results suggest that salt‐fingering instabilities generate substantial nutrient fluxes (on average 0.03 mol N m−2 yr−1) which are of similar magnitude as fluxes associated with mechanically induced turbulence or with mesoscale eddies. Because salt‐fingering activity depends on the proportion of temperature versus salinity effects on stratification rather than on the stability of stratification itself, its sensitivity to climate change will differ from that of “ordinary” mixing processes and needs to be considered in the context of global change.
Formation region of North Pacific subtropical mode water in the late winter of 2003
Authors: Oka Eitarou , Suga Toshio
Published: December 2003

The mixed layer structure and properties in the formation region of the North Pacific Subtropical Mode Water (STMW) east of Japan in the late winter of 2003 were examined using temperature and salinity data primarily from Argo profiling floats. The formation region extends south of the Kuroshio Extension, between 30°N and 35°N and as far east as 175°E. It is characterized by a mixed layer with depths greater than 200db and meridionally uniform temperature between 16.5°C and 18.2°C, associated with a mixed layer front at its southern edge. The mixed layer in the formation region becomes colder, fresher, and denser toward the east, leading to the formation of warmer, saltier, and lighter STMW in the western part of the region. The spatial variation of the mixed layer depth in the formation region corresponds well with the underlying permanent thermocline depth.
Nonlinear dynamics of electrostatic and electromagnetic drift modes in dusty plasmas
Authors: Haque Q. , Saleem H.
Published: December 2003

Coupling of low‐frequency electrostatic and electromagnetic modes in the presence of stationary dust in an electron‐ion plasma is investigated. In the nonlinear case, dipolar vortex structures associated with these perturbations are studied. Comparisons with previous research are presented in several limiting cases, and it is pointed out that dipolar vortex structures seem to be a very common phenomenon in dusty plasmas. Relevance of this work to space and astrophysical plasmas is discussed.
Substorm onset by plasma sheet divergence
Authors: Lyons L. R. , Wang C.‐P. , Nagai T.
Published: December 2003

It is necessary to understand current wedge formation in order to understand the cause of the substorm expansion phase. In the companion paper we used Geotail spacecraft observations to show that the cross‐tail current reduction within the inner‐plasma‐sheet current wedge results from a process that leads to a reduction in equatorial plasma pressure and a substantial reduction in flux tube ion content. Here we use the single‐species continuity equation for plasma sheet particles to identify a plausible cause of these plasma reductions and thus for current wedge formation and the initiation of the substorm expansion phase. Specifically, we find that a convection reduction, which follows a growth phase period of enhanced convection, should cause a divergence of plasma sheet particles driven by diamagnetic drift that leads to flux tube content reduction. We find that the reduction in flux tube content should be longitudinally localized to the premidnight to midnight region where the current wedge has been observed to initially form and that the reduction must initiate within the region of the equatorial mapping of the Harang discontinuity, consistent with ionospheric observations of substorm onset. We also find that the reduction in flux tube content should initially develop slowly and then develop more rapidly as the current wedge forms. This is consistent with observations which show that expansion phase aurora, and thus also the current wedge, develops slowly for a few minutes before brightening rapidly, and it is as required if plasma sheet divergence driven by diamagnetic drift leads to current wedge formation and initiation of the substorm expansion phase.
Global Ozone Monitoring Experiment ozone profile characterization using interpretation tools and lidar measurements for intercomparison
Authors: Meijer Y. J. , van der A R. J. , van Oss R. F. , Swart D. P. J. , Kelder H. M. , Johnston P. V.
Published: December 2003

Global ozone profiles are derived from the ultraviolet and visible part of the spectra of the nadir‐viewing Global Ozone Monitoring Experiment (GOME), which is mounted on the polar orbiting second Earth Remote Sensing satellite (ERS‐2). These profiles need to be characterized, especially since the product includes a priori knowledge and so‐called averaging kernels. This additional information needs to be taken into account when comparing the profiles to correlative measurements. We perform an intercomparison between the ground‐based stratospheric lidar system in Lauder, New Zealand, and collocated GOME data. Here, the satellite profiles are retrieved with the algorithm of the Royal Netherlands Meteorological Institute (KNMI), which uses the optimal estimation method. In the comparison study significant differences are revealed which vary with season and altitude, indicating errors in the retrieval system. However, any quality assessment will just be one part of characterizing an ozone profile product that includes averaging kernels and a priori information. Data users need to be aware of the inherently complicated nature of such products that can only be fully understood when taking into account this additional information. In the second part of the study, the complex relation between the retrieved and the true profile is clarified using several interpretation tools. Applying these tools, we conclude that below 17‐km altitude the GOME profiles can only be used with appropriate use of averaging kernels (e.g., in data assimilation). Above 17 km up to 50 km the GOME spectra contain useful profile information, but the retrieved profiles have a moderate vertical resolution of about 11 km and contain a substantial fraction of a priori information of about 50%.
Heterologous expression of cry2 gene from a local strain of Bacillus thuringiensis isolated in Nigeria
Authors: Ogunjimi Abiodun A. , Chandler John M. , Gbenle George O. , Olukoya Daniel K. , Akinrimisi Ezekiel O.
Published: December 2003

A cry2 gene encoding a larvicidal crystal protein was isolated from a strain of Bacillus thuringiensis found in soil samples in Nigeria. This gene was cloned into plasmid pUC19 and subcloned into both pBluescript (sk+/−) and pPICZαB placed under a T7/AOXI (alcohol oxidase I) promoter respectively and transformed into Escherichia coli and Pichia pastoris. Clones were induced for expression, and the cellular proteins extracted and analysed by SDS/PAGE. Integration of an insert into the yeast chromosome was confirmed by PCR amplification using AOXI primers designed to monitor the intactness of the insertion into the chromosome. The expression cassettes constructed were both expressed in E. coli strain (XL1‐blue) and P. pastoris (SMD1168) respectively. A ≈70 kDa recombinant toxin was obtained both in P. pastoris and E. coli in different quantities. Expression was confirmed by Northern‐blot analysis of 2.0 kb transcripts, obtained from clones induced for RNA transcripts, which hybridized with a [32P]dCTP‐labelled probe prepared from a 641 bp fragment of restriction‐endonuclease‐HaeII‐digested PCR product of the cry2 gene.
Modification of phospholipase C-γ-induced Ca2+ signal generation by 2-aminoethoxydiphenyl borate
Authors: MA Hong-Tao , VENKATACHALAM Kartik , RYS-SIKORA Krystyna E. , HE Li-Ping , ZHENG Fei , GILL Donald L.
Published: December 2003

The mechanisms by which Ca2+-store-release channels and Ca2+-entry channels are coupled to receptor activation are poorly understood. Modification of Ca2+ signals by 2-aminoethoxydiphenyl borate (2-APB), suggests the agent may target entry channels or the machinery controlling their activation. In DT40 B-cells and Jurkat T-cells, complete Ca2+ store release was induced by 2-APB (EC50 10–20 µM). At 75 µM, 2-APB emptied stores completely in both lymphocyte lines, but had no such effect on other cells. In DT40 cells, 2-APB mimicked B-cell receptor (BCR) cross-linking, but no effect was observed in mutant DT40 lines devoid of inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) or phospholipase C-γ2 (PLC-γ2). Like the BCR, 2-APB activated transfected TRPC3 (canonical transient receptor potential) channels, which acted as sensors for PLC-γ2-generated diacylglycerol in DT40 cells. The action of 2-APB on InsP3Rs and TRPC3 channels was prevented by PLC-inhibition, and required PLC-γ2 catalytic activity. However, unlike BCR activation, no increased InsP3 level could be measured in response to 2-APB. Also, calyculin A-induced cytoskeletal reorganization prevented 2-APB-induced InsP3R and TRPC3-channel activation, but not that induced by the BCR. 2-APB still activated TRPC3 channels in DT40 cells with fully depleted Ca2+ stores, indicating its action was not via Ca2+ release. Significantly, 2-APB-induced InsP3R and TRPC3 activation was prevented in DT40 knockout cells devoid of the BCR- and PLC-γ2-coupled adaptor/kinases, Syk, Lyn, Btk or BLNK. The results suggest that 2-APB activates Ca2+ signals in lymphocytes by initiating and enhancing coupling between components of the BCR–PLC-γ2 complex and both Ca2+-entry and Ca2+-release channels.
Investigation into the diet of the central rock-rat (Zyzomys pedunculatus)
Authors: Nano Theresa J. , Smith Cate M. , Jefferys Elizabeth
Published: December 2003

The diet of the rare central rock-rat, Zyzomys pedunculatus, was assessed by microscopic analysis of 18 faecal pellet samples collected from four different sites in the west MacDonnell Ranges in the Northern Territory. Samples were collected from the four sites in summer (n = 13), one site in winter (n = 3), and two sites in spring (n = 2). Four major food categories were observed in the samples: seed, leaf, stem and insect. Seed was by far the most dominant food in the overall diet of Z. pedunculatus, making up 72% of identifiable particles, leaf was secondary (21%), while stem and insects contributed only 3% and 4% respectively. Although the sample size was small, no major seasonal shift between seed and invertebrate dominance was evident. Seed dominated the diet in both summer and winter, though winter seed consumption was lower (78% v. 58%). The level of seed consumption in the two spring samples was highly divergent (38% v. 93%), stressing the need for more samples to be collected from dry periods. Lowered rates of seed consumption during winter and in one of the spring samples were accompanied by increases in leaf consumption. Insect consumption remained low across all sampled seasons, suggesting that this species is not an omnivore. Rather, the dominance of seed in the diet suggests that Z. pedunculatus is primarily a granivore, a finding that has implications for the conservation status and management of this little-known species.
Environmental factors affecting the capture of southern hairy-nosed wombats (Lasiorhinus latifrons) by stunning
Authors: Taggart David A. , Finlayson Graeme R. , Richings Nadine , Shimmin Glenn , Dibben Ron , Adcock Justin , Temple-Smith Peter D.
Published: December 2003

A 'stunning' technique, combining a rifle shot with spotlighting and hand netting was used for the live-capture of southern hairy-nosed wombats. A successful stun was defined as a rifle shot that resulted in the temporary deafening and disorientation of a wombat. When combined with spotlighting, this technique enabled catchers with nets to approach the wombat undetected to secure an easy capture. Environmental factors (temperature, humidity, dew point, light and wind) were examined in order to determine the optimal conditions for the use of this capture procedure. In all, 558 shots were fired, resulting in ~25% of successful stuns. Stunning was primarily affected by temperature and humidity in a normally distributed manner. Stunning was greatest between 12°C and 18°C with a success rate of 40–51%. At temperatures either side of this significantly fewer stuns were achieved, and below 6°C or above 24°C no successful stuns were recorded. Likewise, stunning worked best at humiditys of 70–90%, declined when humidity was >90% and did not work at all at a humidity of 40% or less. Together, temperature and humidity data suggest that air density, for which these parameters are correlates, may be the key component in the success of this capture technique. Variation in stunning success resulting from changes in temperature and humidity may affect either the frequency spectrum of the sound created by the shot or perhaps the manner in which the eardrum receives the sound. Other factors, including dew point and light, also varied significantly with stunning, but were considered of less importance. Whatever the controlling factors, it was clear that stunning, in combination with spotlighting and netting is a rapid, highly effective, and potentially much less stressful method of capturing southern hairy-nosed wombats than the methods that have been used previously.
Public and stakeholder values of wildlife in Victoria, Australia
Authors: Miller Kelly K.
Published: December 2003

This paper explores the management implications of a recent study that was designed to explore public and stakeholder values of wildlife in Victoria, Australia. Questionnaires (n = 1431) were used to examine values and knowledge of wildlife held by residents from seven Victorian municipalities and members of six wildlife management stakeholder groups. The results suggest that most Victorians have a relatively strong emotional attachment to individual animals (the humanistic value) and are interested in learning about wildlife and the natural environment (the curiosity/learning/interacting value). In comparison, the negativistic, aesthetic, utilitarian-habitat and dominionistic/wildlife-consumption values were not expressed as strongly. These findings suggest that wildlife managers should expect support for wildlife management objectives that reflect the relatively strong humanistic orientation of Victorians and tailor management and education programs to appeal to this value and Victorians' interest in learning about wildlife.
Developing a census method based on sight counts to estimate rabbit (Oryctolagus cuniculus) numbers
Authors: Poole Dylan W. , Cowan Dave P. , Smith Graham C.
Published: December 2003

A rabbit-census method, based on systematic counts conducted at night or at dawn and dusk, was developed and validated in terms of estimating the total number of rabbits present in a given area. Initially, models were developed under semi-natural conditions to describe the relationships between the numbers of rabbits counted and population size. Confidence limits were also calculated. The models were developed by comparing rabbit counts with the actual number of rabbits present, from a known population of animals. Only spotlight counts at night were considered reliable enough to estimate rabbit population size. During the autumn and winter months these represented ~60% of the population present. The model was subsequently validated, in two different exercises, following a series of field trials conducted under a variety of conditions on commercial farms. Initially, population estimates derived from the model were compared with those calculated using an alternative census technique. Population estimates, using the two techniques, were very similar at nine of the ten study sites. A second validation exercise was also conducted whereby the number of rabbits removed at each of the sites was compared with the difference between the mean pre- and post-removal spotlight counts. The results further supported the proposition that spotlight counts represent ~60% of the population present, with the difference between the two mean spotlight counts representing 61.2% (± 11.0, s.d.) of the number of rabbits removed. The census method therefore shows considerable promise as a means to estimate rabbit numbers under a range of agricultural conditions and therefore has the potential to predict accurately the economic costs of rabbit damage and also to gauge the effectiveness of various methods of rabbit control.
The effects of a low-intensity fire on small mammals and lizards in a logged, burnt forest
Authors: Penn Angela M. , Sherwin William B. , Lunney Daniel , Banks Peter B.
Published: December 2003

This study summarises the results of a patchy, low-intensity hazard-reduction burn on the small mammals and lizards of Mumbulla State Forest and Biamanga National Park. About half of the study sites in the patchwork of alternate logging regrowth and unlogged forest had been burnt in April 1999. Prior to burning (winter 1998), there were significantly more Antechinus agilis in those north-west-facing sites that burnt in 1999, than in the south-east sites that burnt. By 15 months post-burning this trend had reversed, with more A. agilis in the burnt south-east sites. In contrast, burning had an initially positive effect on the abundance of Rattus fuscipes, with significantly more in the burnt south-east than burnt north-west sites four months post-burning compared with 1998 (pre-burning). This influence of aspect may be attributable to the fact that fires generally burn more intensely on the drier north-west slopes, removing more of the leaf litter and vegetative cover and making post-fire conditions harsher. Antechinus swainsonii became extremely scarce in the forest after the burning. Twenty months post-burning (summer 2000), there were significantly more Lampropholis delicata in the unburnt sites than in the burnt sites compared with 1999 (10 months post-burn). Lampropholis guichenoti were affected to a much lesser extent and recovered quickly, and Eulamprus heatwolei were generally unaffected by the burning. The hazard-reduction burn came 19 years after a high-intensity bushfire and logging operation in this forest. The results of the two fires were similar for the two Antechinus species and the Eulamprus species but contrasted for the other species. Hazard-reduction burning is widespread and accepted as a management tool and, following the New South Wales bushfires of 1994–95 and 2001–02, will probably increase in use. Our results, however, suggest that the biodiversity impacts of burning are complex and multidirectional, posing a significant challenge to conservation managers.
Reproduction of Lumholtz's tree-kangaroo, Dendrolagus lumholtzi (Marsupialia : Macropodidae) in captivity, with age estimation and development of the pouch young
Authors: Johnson Peter M. , Delean Steven
Published: December 2003

Reproduction in Lumholtz's tree kangaroo, Dendrolagus lumholtzi, was studied in captivity. The length of the oestrous cycle was 47–64 days and the gestation period was 42–48 days. Post partum oestrus and embryonic diapause were not observed in this study. The interval between loss of a pouch young and a return mating was 22 days. Pouch life was 246–275 days long and weaning occurred 87–240 days later. Sexual maturity was obtained in females as early as 2.04 years and in males at 4.6 years. Linear mixed-effects models are used to describe polynomial growth equations for age determination of pouch young using both head and pes length. The relationship between error in age prediction and each body measurement is also defined. Head and pes measurements provide equally accurate estimates of the age of pouch young.
Satellite cells attract monocytes and use macrophages as a support to escape apoptosis and enhance muscle growth
Authors: Chazaud Bénédicte , Sonnet Corinne , Lafuste Peggy , Bassez Guillaume , Rimaniol Anne-Cécile , Poron Françoise , Authier François-Jérôme , Dreyfus Patrick A. , Gherardi Romain K.
Published: December 2003

Once escaped from the quiescence niche, precursor cells interact with stromal components that support their survival, proliferation, and differentiation. We examined interplays between human myogenic precursor cells (mpc) and monocyte/macrophages (MP), the main stromal cell type observed at site of muscle regeneration. mpc selectively and specifically attracted monocytes in vitro after their release from quiescence, chemotaxis declining with differentiation. A DNA macroarray–based strategy identified five chemotactic factors accounting for 77% of chemotaxis: MP-derived chemokine, monocyte chemoattractant protein-1, fractalkine, VEGF, and the urokinase system. MP showed lower constitutive chemotactic activity than mpc, but attracted monocytes much strongly than mpc upon cross-stimulation, suggesting mpc-induced and predominantly MP-supported amplification of monocyte recruitment. Determination of [3H]thymidine incorporation, oligosomal DNA levels and annexin-V binding showed that MP stimulate mpc proliferation by soluble factors, and rescue mpc from apoptosis by direct contacts. We conclude that once activated, mpc, which are located close by capillaries, initiate monocyte recruitment and interplay with MP to amplify chemotaxis and enhance muscle growth.
ARF6 controls post-endocytic recycling through its downstream exocyst complex effector
Authors: Prigent Magali , Dubois Thierry , Raposo Graça , Derrien Valérie , Tenza Danièle , Rossé Carine , Camonis Jacques , Chavrier Philippe
Published: December 2003

The small guanosine triphosphate (GTP)–binding protein ADP-ribosylation factor (ARF) 6 regulates membrane recycling to regions of plasma membrane remodeling via the endocytic pathway. Here, we show that GTP–bound ARF6 interacts with Sec10, a subunit of the exocyst complex involved in docking of vesicles with the plasma membrane. We found that Sec10 localization in the perinuclear region is not restricted to the trans-Golgi network, but extends to recycling endosomes. In addition, we report that depletion of Sec5 exocyst subunit or dominant inhibition of Sec10 affects the function and the morphology of the recycling pathway. Sec10 is found to redistribute to ruffling areas of the plasma membrane in cells expressing GTP-ARF6, whereas dominant inhibition of Sec10 interferes with ARF6-induced cell spreading. Our paper suggests that ARF6 specifies delivery and insertion of recycling membranes to regions of dynamic reorganization of the plasma membrane through interaction with the vesicle-tethering exocyst complex.
Chromosome instability in colorectal tumor cells is associated with defects in microtubule plus-end attachments caused by a dominant mutation in APC
Authors: Green Rebecca A. , Kaplan Kenneth B.
Published: December 2003

The attachment of microtubule plus ends to kinetochores and to the cell cortex is essential for the fidelity of chromosome segregation. Here, we characterize the causes underlying the high rates of chromosome instability (CIN+) observed in colorectal tumor cells. We show that CIN+ tumor cells exhibit inefficient microtubule plus-end attachments during mitosis, accompanied by impairment of chromosome alignment in metaphase. The mitotic abnormalities associated with CIN+ tumor cells correlated with status of adenomatous polyposis coli (APC). Importantly, we have shown that a single truncating mutation in APC, similar to mutations found in tumor cells, acts dominantly to interfere with microtubule plus-end attachments and to cause a dramatic increase in mitotic abnormalities. We propose that APC functions to modulate microtubule plus-end attachments during mitosis, and that a single mutant APC allele predisposes cells to increased mitotic abnormalities, which may contribute to tumor progression.
Phage display reveals 52 novel extracellular and transmembrane proteins from Lactobacillus reuteri DSM 20016T
Authors: Wall Torun , Roos Stefan , Jacobsson Karin , Rosander Anna , Jonsson Hans
Published: December 2003

Extracellular and transmembrane proteins are important for the binding of bacteria to intestinal surfaces and for their interaction with the host. The aim of this study was to identify genes encoding extracellular and transmembrane proteins from the probiotic bacterium Lactobacillus reuteri by construction and screening of a phage display library. This library was constructed by insertion of randomly fragmented DNA from L. reuteri into the phagemid vector pG3DSS, which was previously developed for screening for extracellular proteins. After affinity selection of the library, the L. reuteri inserts were sequenced and analysed with bioinformatic tools. The screening resulted in the identification of 52 novel genes encoding extracellular and transmembrane proteins. These proteins were classified as: transport proteins; enzymes; sensor–regulator proteins; proteins involved in host/microbial interactions; conserved hypothetical proteins; and unconserved hypothetical proteins. Further characterization of the extracellular and transmembrane proteins identified should contribute to the understanding of the probiotic properties of L. reuteri.
The surface (S-) layer is a virulence factor of Bacteroides forsythus
Authors: Sabet M. , Lee S.-W. , Nauman R. K. , Sims T. , Um H.-S.
Published: December 2003

Bacteroides forsythus has emerged as a crucial periodontal pathogen with possible implications for systemic disease. The aim of this study was to isolate the S-layer from B. forsythus and examine its virulence potential as a part of efforts to characterize virulence factors of B. forsythus. The role of the S-layer in the haemagglutinating and adherent/invasive activities was evaluated. It was observed that the S-layer alone was able to mediate haemagglutination. In adherent and invasive studies, transmission electron microscopy clearly revealed that B. forsythus cells were able to attach to and invade KB cells, showing the formation of a microvillus-like extension around adherent and intracellular bacteria. The quantitative analysis showed that five different B. forsythus strains exhibited attachment (1·9–2·3 %) and invasion (0·4–0·7 %) capabilities. It was also observed through antibody inhibition assays that adherent/invasive activities of B. forsythus are mediated by the S-layer. Furthermore, an in vivo immunization study adopting a murine abscess model was used to prove that the S-layer is involved in the infectious process of abscess formation. While mice immunized with purified S-layer and B. forsythus whole cells did not develop any abscesses when challenged with viable B. forsythus cells, unimmunized mice developed abscesses. Collectively, the data obtained from these studies indicate that the S-layer of B. forsythus is a virulence factor.
The CepIR quorum-sensing system contributes to the virulence of Burkholderia cenocepacia respiratory infections
Authors: Sokol P. A. , Sajjan U. , Visser M. B. , Gingues S. , Forstner J. , Kooi C.
Published: December 2003

ThecepIRgenes encode anN-acyl homoserine lactone (AHL)-dependent quorum-sensing system consisting of an AHL synthase that directs the synthesis ofN-octanoyl-l-homoserine lactone (ohl) andn-hexanoyl-l-homoserine lactone and a transcriptional regulator. The virulence ofcepIRmutants was examined in two animal models. Rats were infected with agar beads containingBurkholderia cenocepaciaK56-2, K56-I2 (cepI : : Tpr) or K56-R2 (cepR : : Tn5-OT182). At 10 days post-infection, the extent of lung histopathological changes was significantly lower in lungs infected with K56-I2 or K56-R2 compared to the parent strain. Intranasal infections were performed inCftr(−/−)mice and their wild-type siblings. K56-2 was more virulent in both groups of mice. K56-I2 was the least virulent strain and was not invasive in theCftr(−/−)mice. OHL was readily detected in lung homogenates fromCftr(−/−)mice infected with K56-2 but was only detected at levels slightly above background in a few mice infected with K56-I2. Lung homogenates from mice infected with K56-2 had significantly higher levels of the inflammatory mediators murine macrophage inflammatory protein-2,KC/N51, interleukin-1βand interleukin-6 than those from K56-I2-infected animals. These studies indicate that a functional CepIR quorum-sensing system contributes to the severity ofB. cenocepaciainfections. A zinc metalloprotease gene (zmpA) was shown to be regulated by CepR and may be one of the factors that accounts for the difference in virulence between thecepImutant and the parent strain.
A polyketide synthase gene required for ochratoxin A biosynthesis in Aspergillus ochraceus
Authors: O'Callaghan J. , Caddick M. X. , Dobson A. D. W.
Published: December 2003

Ochratoxin A is an important nephrotoxic and nephrocarcinogenic mycotoxin, produced by Aspergillus ochraceus as a polyketide-derived secondary metabolite. A portion of a putative polyketide synthase gene (pks) involved in the biosynthesis of this mycotoxin was cloned by using a suppression subtractive hybridization PCR-based approach. The predicted amino acid sequence of the 1·4 kb clone shared 28–35 % identity to acyl transferase regions from fungal polyketide synthases found in the databases. Based on reverse transcription PCR studies, the pks gene is expressed only under ochratoxin A permissive conditions and only during the early stages of the mycotoxin synthesis. A mutant in which the pks gene has been interrupted cannot synthesize ochratoxin A. This report is the first of the cloning and characterization of a gene involved in ochratoxin A biosynthesis.
The Bradyrhizobium japonicum napEDABC genes encoding the periplasmic nitrate reductase are essential for nitrate respiration
Authors: Delgado María J. , Bonnard Nathalie , Tresierra-Ayala Alvaro , Bedmar Eulogio J. , Müller Peter
Published: December 2003

The napEDABC gene cluster that encodes the periplasmic nitrate reductase from Bradyrhizobium japonicum USDA110 has been isolated and characterized. napA encodes the catalytic subunit, and the napB and napC gene products are predicted to be a soluble dihaem c and a membrane-anchored tetrahaem c-type cytochrome, respectively. napE encodes a transmembrane protein of unknown function, and the napD gene product is a soluble protein which is assumed to play a role in the maturation of NapA. Western blots of the periplasmic fraction from wild-type cells grown anaerobically with nitrate revealed the presence of a protein band with a molecular size of about 90 kDa corresponding to NapA. A B. japonicum mutant carrying an insertion in the napA gene was unable to grow under nitrate-respiring conditions, lacked nitrate reductase activity, and did not show the 90 kDa protein band. Complementation of the mutant with a plasmid bearing the napEDABC genes restored both nitrate-dependent anaerobic growth of the cells and nitrate reductase activity. A membrane-bound and a periplasmic c-type cytochrome, with molecular masses of 25 kDa and 15 kDa, respectively, were not detected in the napA mutant strain incubated anaerobically with nitrate, which identifies those proteins as the NapC and the NapB components of the B. japonicum periplasmic nitrate reductase enzyme. These results suggest that the periplasmic nitrate reductase is the enzyme responsible for anaerobic growth of B. japonicum under nitrate-respiring conditions. The promoter region of the napEDABC genes has been characterized by primer extension. A major transcript initiates 66·5 bp downstream of the centre of a putative FNR-like binding site.
Involvement of DivIVA in the morphology of the rod-shaped actinomycete Brevibacterium lactofermentum
Authors: Ramos Angelina , Honrubia María Pilar , Valbuena Noelia , Vaquera José , Mateos Luis M. , Gil José A.
Published: December 2003

In Brevibacterium lactofermentum, as in many Gram-positive bacteria, a divIVA gene is located downstream from the dcw cluster of cell-division- and cell-wall-related genes. This gene (divIVABL
) is mostly expressed during exponential growth, and the protein encoded, DivIVABL, bears some sequence similarity to antigen 84 (Ag84) from mycobacteria and was detected with monoclonal antibodies against Ag84. Disruption experiments using an internal fragment of the divIVABL
gene or a disrupted divIVABL
cloned in a suicide conjugative plasmid were unsuccessful, suggesting that the divIVABL
gene is needed for cell viability in Brev. lactofermentum. Transformation of Brev. lactofermentum with a multicopy plasmid containing divIVABL
drastically altered the morphology of the corynebacterial cells, which became larger and bulkier, and a GFP fusion to DivIVABL mainly localized to the ends of corynebacterial cells. This localization pattern, together with the overproduction phenotype, suggests that DivIVA may be important in regulating the apical growth of daughter cells.
Implementation of virtual manufacturing by a technology licensing company
Authors: Webster Margaret , Sugden David
Published: December 2003

The paper considers the implementation of a virtual manufacturing system as an alternative to outward technology licensing in a high technology industrial sector. Brief theoretical definition and description of the two strategy options is provided to give background and context. This is followed by empirical material from a longitudinal case study of a company that has developed a virtual manufacturing system in addition to its pre‐existing outward technology licensing business stream. A summary account of the company history and development is followed by description of the virtual manufacturing proposal. Analysis of this identified a number of competencies that would be required in order to succeed. The final part of the paper describes the company's response to this analysis and discusses early implementation of the virtual system. It is shown that implementation of the proposal has represented a positive response to the business challenges facing the company.
The SHEN model for MTO SMEs
Authors: Shaladdin Muda Mohd , Hendry Linda
Published: December 2003

This paper presents a new model developed for make‐to‐order (MTO) companies to aid in determining appropriate content for performance improvement programmes. The model has been developed using literature evidence and case‐study data from six MTO small and medium‐sized enterprises (SMEs). As well as being important aspects of the new model, some of the conclusions from the case‐study evidence are important insights into best practice in MTO companies in their own right. In particular, the evidence suggests that the highly‐specialised MTO environment means that multi‐skilling is less important than it is in less skilled industries. It is also suggested that the need for simple, movable equipment is less important because these companies often need specialised machinery and maintain a flexibility of process through a traditional functional layout.
Logistics in relation to strategy in dairying
Authors: Sankaran Jayaram K. , Luxton Patrick
Published: December 2003

The earliest known instance of scholarly writing on logistics (in 1901) is actually located in agribusiness. While case illustrations of productivity improvements in logistics in agribusiness have routinely featured in the academic literature since then, such efficiency gains are rarely cast in a broader, strategic perspective – a somewhat surprising omission. Consequently, this study seeks to clarify the relationship between logistics and generic business strategy in dairy organisations/industries by using the New Zealand dairy industry as a case in point. (The focus is more on operations than on distribution and service). We first clarify that the New Zealand dairy co‐operatives and the (export‐oriented) New Zealand dairy industry as a whole, have generally followed a strategy of cost leadership. We then review the various ways in which efficiency has been realised in logistics in the industry, and especially dwell on how the structure (e.g. co‐operative ownership, vertical integration) of the dairy industry has supported and/or hindered the focus on cost leadership. We also examine the extent to which our analysis of supply‐chain efficiency extends to other dairy organisations/industries.
Discrete choice models and valuation experiments
Authors: Mazzanti Massimiliano
Published: December 2003

This paper presents the results of a choice experiment carried out from August to October 2000 on the visitors of the Galleria Borghese Museum, a worldwide known heritage site located in Rome. The main objective of this work is to study the relevancy of choice experiment techniques as a tool aimed at measuring economic values and assessing user preferences concerning the multi‐attribute and multi‐value services as supplied by cultural institutions. A set of alternative incremental changes in service attributes showing improvements in supply are designed and presented to visitors. Alternative conditional logit specifications are used for analysing stated choices over the hypothetical incremental changes in museum attributes. Willingness to pay for incremental variations concerning site attributes is positive and statistically significant for most changes. Conditional logit specifications, which incorporate heterogeneity by adding interaction socio‐economic terms, are generally robust and do not violate the IIA assumption. In addition, in the present case study, non‐IIA models do not outperform conditional logit models. Choice experiments confirm as being a practical and effective tool for non‐market valuation, and they should be used to provide information to decision makers for justifying demand led policies.
Does FDI inflow crowd out domestic investment in Korea?
Authors: Deok‐Ki Kim David , Seo Jung‐Soo
Published: December 2003

This paper provides empirical evidence on the dynamic relationship between inward foreign direct investment (FDI), economic growth and domestic investment in Korea for the period 1985‐1999. By employing a vector autoregression model and the innovations accounting techniques, we explore dynamic interactions between inward FDI, domestic investment and output. We find that FDI has some positive effects on economic growth, but its effects seem to be insignificant. On the other hand, economic growth is found to have statistically significant and highly persistent effects on the future level of FDI. Although FDI is exogenous contemporaneously, we find that FDI shows strong dynamic endogeneity to domestic macroeconomic conditions, which has not been uncovered in previous works. Our finding does not support the view that FDI crowds out domestic investment in Korea.
The impact of export growth and scale economies on productivity in Singapore's manufacturing industries
Authors: Thangavelu S.M. , Owyong David T.
Published: December 2003

This paper examines the impact of export performance and scale economies on total factor productivity in Singapore's manufacturing sector. A panel data of total of ten major industries within its manufacturing sector are analysed over the period 1974‐1995. It was found that export growth and scale economies contributed significantly to the productivity growth of selected industries. In addition, the results also indicate that the foreign direct investment (FDI) intensive industries are the main contributors to productivity growth in the manufacturing industries in terms of export performance and economies of scale as compared to the non‐FDI intensive industries.