bluuebunny/crossref_metadata_2025 huggingface dataset:
The acid flux dynamics of two artificial drains in acid sulfate soil backswamps on the Clarence River floodplain, Australia
Authors: Johnston S. G. , Slavich P. , Hirst P.
Published: September 2004

The export of acidity, iron, aluminium, and sulfate to an estuary from 2 drains in acid sulfate soil backswamps was monitored over 18 months. The backswamps had similar geomorphology, stratigraphy, and drainage density, and comparable soil and groundwater acidity. However, the flux rates, temporal dynamics, and export pathways of acid and other sulfide oxidation products varied greatly and were controlled to first order by (i) the saturated hydraulic conductivity (K) of sulfuric horizons and (ii) the tidally influenced groundwater gradients. The site with very high K and large tidally influenced groundwater gradients had high acid flux rates (5300 mol H+/ha.year), chronic acid discharge, high drain water acid and metal concentrations, and the primary flux pathway was direct groundwater seepage (interflow/bypass flow) to the drain. The site with lower K and smaller groundwater gradients displayed low acid flux rates (50 mol H+/ha.year), infrequent, highly episodic discharge, and the primary flux pathway was dilute surface runoff following dissolution of sulfide oxidation products accumulated on the soil surface. Importantly, the majority of acid export at both sites occurred while the backswamp groundwater level was within a very narrow elevation range.
Sample pre-treatment and the determination of some chemical properties of acid sulfate soil materials
Authors: Maher Crystal A. , Sullivan Leigh A. , Ward Nicholas J.
Published: September 2004

This study provides a systematic analysis of the effect of common acid sulfate soil (ASS) sample pre-treatments (namely freezing, oven drying, and grinding) on chromium-reducible sulfur (SCR) and water-soluble sulfate determinations. The results show that oven drying and hand grinding of the samples prior to analysis resulted in a decrease in SCR (i.e. up to 20% compared to those of frozen samples). This lower SCR value was partly due to the oxidation of sulfides in the oven. For oven-dried ASS materials, more intensive grinding in a ring mill increased SCR values, most likely by abrading coatings from pyrite grains. For oven-dried mineral ASS materials the highest SCR values were obtained with 1 min of ring mill grinding, but for soils with appreciable organic matter (such as peat), 5 min of ring mill grinding gave the highest values. The results indicate that for some ASS materials, oven drying, regardless of the ensuing grinding procedure, results in underestimated SCR values. This study also demonstrates that an artifact of oven drying ASS materials can be greatly increased water-soluble sulfate contents.
Redistribution of monosulfidic black oozes by floodwaters in a coastal acid sulfate soil floodplain
Authors: Bush Richard T. , Sullivan Leigh A. , Fyfe Diane , Johnston Scott
Published: September 2004

The observations presented in this paper illustrate that significant amounts of monosulfidic black oozes (MBO) were eroded from flood mitigation drainage canals and redistributed across a coastal floodplain during a flood event associated with extreme deoxygenation and a massive fish kill. MBO are organic materials enriched in iron monosulfides and thick layers can accumulate in drains affected by acid sulfate soils. Laboratory studies have demonstrated that MBO can react rapidly when brought into suspension to completely consume dissolved oxygen. The abundance of MBO in flood mitigation drains and their extreme reactivity implicated MBO in the acute deoxygenation of the Richmond River, north-eastern New South Wales, Australia, following a major flood in February 2001. The field observations of MBO redistribution provide valuable evidence to help explain how these materials may interact and contribute to the deoxygenation of floodwaters.
Occurrence and abundance of monosulfidic black ooze in coastal acid sulfate soil landscapes
Authors: Bush Richard T. , Fyfe Diane , Sullivan Leigh A.
Published: September 2004

Organic oozes enriched in iron monosulfides are called monosulfidic black ooze (MBO). The occurrence and abundance of MBO were quantified in natural tributaries and man-made drainage canals on a typical coastal river floodplain. Thick deposits of MBO occurred in drains and the protected upper reaches of tributaries in acid sulfate soil (ASS) areas. Acid-tolerant lilies grew prolifically in these areas, contributing large amounts of decaying organic debris. The MBO contained up to 6.3% acid-volatile sulfur (equivalent to 18% iron monosulfide), an order of magnitude greater than reported previously for natural sediments. It also contained up to 6% pyritic sulfur (equivalent to approximately 11% pyrite). Sulfate and iron from surrounding ASS combined with abundant organic matter and protected flow in ASS drains provide excellent conditions for sulfate reduction, leading to iron sulfide precipitation and the accumulation of organic detritus. When mixed with water, the iron monosulfide in MBO can react within minutes to completely consume dissolved oxygen. There are thousands of drains in ASS areas that may have thick deposits of MBO. The MBO has the potential to cause rapid and severe effects on water quality. The challenge is to develop management practices that reduce the formation and accumulation of MBO in acid sulfate landscapes.
Soil properties in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia
Authors: Rosicky Mark A. , Sullivan Leigh A. , Slavich Peter G. , Hughes Mike
Published: September 2004

Soil profiles in 10 persistently bare areas (i.e. scalds), mainly located in coastal backswamps of New South Wales, Australia, were examined for chromium-reducible sulfur content and selected chemical properties. At 5 of the sites, the adjacent paddocks with vegetation cover were also examined. All of the tested sites had been affected by the extensive drainage of the surrounding acid sulfate soil (ASS) landscapes and the consequent oxidation of pyrite. All sites had low pH values in the surface soil layers and these low pH values extended for up to 150 cm into the underlying unoxidised blue/grey pyritic estuarine gels. This can be attributed to the downward diffusion of acidity, either produced in the overlying oxidised zones of these soils or transported laterally across the landscape to these low-lying areas. Acidified unoxidised pyritic zones 120 cm thick can evidently form within several decades after drainage disturbance. At the scalded sites the depth from the soil surface to the main pyritic zone varied from the surface to >200 cm depth, indicating that this variable is not critical to ASS scald formation. For most of the sites examined, the chromium-reducible sulfur contents in the surface soil layers were appreciably higher than those in the immediately underlying soil layers. In most of the vegetated sites the chromium-reducible sulfur content in the surface layers was considerably higher than for the adjacent scalded site. The conditions necessary for pyrite formation (i.e. adequate supplies of organic matter, soluble iron, sulfate, and waterlogging) were found to exist at all sites, and the pyrite accumulations in these surface soil layers are considered to be neo-formed. The vegetated soil-profile pyrite and pH results were very similar to their scalded counterparts except that they had an extra 20–40 cm layer of vegetation and mulch that was missing from the scalded profiles. This indicates that there is considerable potential for more extensive scalding in these ASS areas.
Net N mineralisation in acid sulfate soils amended with different sources of organic matter, lime, and urea
Authors: Hoa Nguyen My , Trang Trinh Thi Thu , Tinh Tran Kim
Published: September 2004

Acid sulfate soils in the Mekong Delta, Vietnam, are often high in organic matter content, but net N mineralisation is low. This may be due to low soil pH or low easily decomposable organic matter content. This study aimed at investigating net N mineralisation in acid sulfate rice soil (anaerobic incubation) and acid sulfate upland soil (aerobic incubation) amended with 1% biogas sludge, 1% straw, 1% starch, 2.5‰ CaCO3 (about 10 t CaCO3/ha for acid sulfate soils), and 0.22‰ urea. Non-acid alluvial soils were used for comparison.
Results showed that addition of straw and starch to acid sulfate rice soil decreased net N mineralisation, but addition of biogas sludge increased cumulative N-NH4 due to both the increase in soil pH after submergence and the supply of low C/N organic matter. Addition of biogas sludge can therefore increase N-supplying capacity in acid sulfate rice soil. During aerobic incubation of acid sulfate upland soil with biogas sludge, cumulative N (NH4 + NO3) was also increased compared with the control, although pH was not increased. It is concluded, therefore, that in acid sulfate soils in the Mekong Delta, the supply of easily decomposable organic matter with low C/N ratio can increase activity of microorganisms and hence increase net N mineralised compared with soils not supplied with biogas sludge. Liming can increase net N mineralisation in acid sulfate rice soil during anaerobic incubation, but not in acid sulfate upland soil during aerobic incubation. Addition of rice straw and starch to soil amended with urea increased N immobilisation; therefore, urea can be temporally immobilised in soils and hence may reduce loss of N in field conditions.
Decision trees for farm management on acid sulfate soils, Mekong Delta, Viet Nam
Authors: Tri Le Quang , van Mensvoort M. E. F.
Published: September 2004

Our study shows how farmers in the Mekong Delta, Viet Nam, have developed new cropping systems and management practices to overcome the constraints of their land. Decision trees for land evaluation at farm level, combining farmer and expert knowledge, were developed to support management decisions and to indicate possibilities to improve land suitability.
Our study concentrates on 2 districts, Tan Thanh (fresh water, deep flood, acid soils) and Hong Dan (acid soils, shallow flood, salt surface water). We recommend double rice, yam, sugarcane, and Melaleuca cajiputi for Tan Thanh, and double rice, rice combined with shrimp, single shrimp or crab, sugarcane, bamboo, and Melaleuca for Hong Dan. We show the land-related constraints and how they can be lifted.
Quantification of current and future leaching of sulfur and metals from Boreal acid sulfate soils, western Finland
Authors: Österholm Peter , Åström Mats
Published: September 2004

The leaching of sulfur (S) and metals (Al, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Ni, Zn) from an acid sulfate soil (ASS) area in western Finland was determined on the basis of hydrochemical analyses (ICP-MS) of water samples collected monthly for 3 years from the stream draining that area. The average annual amount of leaching was as follows (kg/ha.year): S (633), Ca (281), Mg (199), Al (54), K (54), Mn (35), Fe (5.6), Zn (1.7), Ni (0.84), Co (0.79), Cu (0.070), Cd (0.0068). These high values are due to extensive oxidation of metal sulfides and weathering of minerals in the ASS profile. Calculations showed that other S inputs such as deposition and fertiliser use, and S outputs such as degassing and plant removal, are insignificant in comparison with current leaching losses. Before the area was artificially drained, the leaching losses of S from the study area must have been very small; otherwise, the S residual in the soil would have been depleted a long time ago. With current drainage practices, the leachable soil S residual will be halved in roughly 30 years, after which the S and metal loads of the drainage will have decreased. However, more time is needed before the concentrations will have decreased to an environmentally acceptable level, unless environmentally friendly measures are found and implemented.
Acid sulfate soils in dredged materials from tidal Pocomoke Sound in Somerset County, MD, USA
Authors: Demas S. Y. , Hall A. M. , Fanning D. S. , Rabenhorst M. C. , Dzantor E. K.
Published: September 2004

Seepage and runoff waters from soils forming in sulfide-bearing dredge materials (SBDM) can have dramatic effects on water quality if they are placed adjacent to open water and do not have adequate containment. Soils forming in SBDM can produce large amounts of acidity upon sulfide oxidation and the oxidation and hydrolysis of released ferrous iron when they are drained or otherwise exposed to air. These soils, under certain environmental conditions, can produce low pH seepage and runoff waters containing large amounts of iron and aluminum, especially after heavy rain that follows a prolonged dry period. During the course of the soil survey update of Somerset County, Maryland (MD), USA, 2 areas of soils forming in SBDM of differing age were identified in close proximity to the sites of recent fish kills on the Pocomoke Sound in Somerset County. Both of these soil areas were initially contained by earthen berms. The dredge materials were deposited directly over the natural tidal marsh soil. Soils forming in SBDM that are approximately 60 years of age were classified as fine-silty, mixed mesic Sulfic Endoaquepts, while the second area of SBDM are 8 years of age and classified as fine-silty, mixed, mesic Typic Sulfaquepts, by Soil Taxonomy. The presence of jarosite was confirmed in both soils by X-ray diffraction, and the presence of ironstone (iron oxyhydroxides) was confirmed in both soils at the effluent discharge points. This is an indication that these soils have undergone intensive acid sulfate weathering (sulfuricization) and that they have released a large quantity of iron to waters leaving the sites. Studies have shown that the 2 mechanisms responsible for acid production from soils forming in SBDM are (i) the oxidation and hydrolysis of mobile ferrous iron; and (ii) the oxidation of the sulfur occurring in the form of pyrite. It is suggested that the resultant low pH, Fe- and Al-enriched water from these soils that entered the Pocomoke Sound may have made fish more susceptible to microbial predation by weakening mucous membranes and/or by promoting the growth of harmful cyannobacteria and flagellates. This paper reports the nature and classification of soils that developed in SBDM at 2 sites of differing age and of the possible environmental impacts of seepage and runoff from these sites entering the Pocomoke Sound.
The response of partially oxidised acid sulfate soil materials to anoxia
Authors: Ward Nicholas J. , Sullivan Leigh A. , Bush Richard T.
Published: September 2004

Four acid sulfate soil (ASS) materials were subjected to anoxia after varying periods of oxidation to determine the geochemical response of these types of soils to flooding. The response of the partially oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification, and the production of soluble oxidation products such as sulfate, iron, and aluminium generally decreased markedly when subjected to anoxia. However, especially in the highly acidic ASS materials (i.e. pH <3.5), sulfide oxidation and acidification generally continued (albeit at much slower rates), most probably due to oxidation by Fe3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur (SCR) formed over 60 days of anoxia. This substantial sulfide re-formation was accompanied by only a slight increase in pH. Minimal sulfide re-formation occurred in 2 of the ASS materials when placed in anoxic conditions, most likely due to a lack of readily available organic matter in these materials. The results show that the imposition of anoxic conditions on partially oxidised ASS materials is generally effective in decreasing the rates of further sulfide oxidation, acidification, and the production of soluble sulfide oxidation products. Biogeochemical sulfide formation consumes acidity; however, sulfide re-formation was ineffective in reversing acidification under the conditions of this experiment. The results indicate that the treatment of sites containing actual ASS materials by management strategies relying on oxygen exclusion need to be accompanied by other strategies that include acidty neutralisation or containment.
A two-stage decision support tool for restoring tidal flows to flood mitigation drains affected by acid sulfate soil: case study of Broughton Creek floodplain, New South Wales, Australia
Authors: Glamore William , Indraratna Buddhima
Published: September 2004

A 2-stage flood estimation and water quality decision support tool (DST) was developed, calibrated, and applied to a field site in south-eastern New South Wales (NSW) to simulate tidal restoration in a flood mitigation drain affected by acid sulfate soils leachate. The first stage of the DST employs a digital terrain map, geographic information tools, and measured water levels to calculate drain water overtopping due to tidal variations. Simulations using the GIS technique at the study site indicated that the primary drainage network can safely contain full tidal flushing (0.91 m AHD or a 58% increase), whereas at the same level the secondary drainage network overtops along relict drainage channels. The second stage of the DST simulates the change in drain water quality using an ion-specific program code written within the open interface PHREEQC program. The results from the water quality model were calibrated against laboratory titration tests. Drain water pH was shown to increase above 6.0, and soluble aluminium and iron concentrations decreased by 73% and 56%, respectively. The extent of water quality change is directly related to the ionic strength of the intruding water and the ion-specific reaction kinetics of aluminium, iron, and sulfate.
A distinct “side population” of cells with high drug efflux capacity in human tumor cells
Authors: Hirschmann-Jax C. , Foster A. E. , Wulf G. G. , Nuchtern J. G. , Jax T. W. , Gobel U. , Goodell M. A. , Brenner M. K.
Published: September 2004

A subset of stem cells, termed the “side population” (SP), has been identified in several tissues in mammalian species. These cells maintain a high efflux capability for antimitotic drugs. We have investigated whether functionally equivalent stem cells also may be detected in human cancers. We initially examined primary tumor cells from 23 patients with neuroblastoma and cell lines derived from a range of other tumors. A distinct SP was found in neuroblastoma cells from 15 of 23 patients (65%). The SP was capable of sustained expansion
ex vivo
and showed evidence for asymmetric division, generating both SP and non-SP progeny. These cells also expressed high levels of
ABCG2
and
ABCA3
transporter genes and had a greater capacity to expel cytotoxic drugs, such as mitoxantrone, resulting in better survival. A SP also was detected in breast cancer, lung cancer, and glioblastoma cell lines, suggesting that this phenotype defines a class of cancer stem cells with inherently high resistance to chemotherapeutic agents that should be targeted during the treatment of malignant disease.
Natural antibodies sustain differentiation and maturation of human dendritic cells
Authors: Bayry Jagadeesh , Lacroix-Desmazes Sébastien , Donkova-Petrini Vladimira , Carbonneil Cédric , Misra Namita , Lepelletier Yves , Delignat Sandrine , Varambally Sooryanarayana , Oksenhendler Eric , Lévy Yves , Debré Marianne , Kazatchkine Michel D. , Hermine Olivier , Kaveri Srini V.
Published: September 2004

The differentiation and maturation of dendritic cells (DCs) is governed by various signals in the microenvironment. Monocytes and DCs circulate in peripheral blood, which contains high levels of natural antibodies (NAbs). NAbs are germ-line-encoded and occur in the absence of deliberate immunization or microbial aggression. To assess the importance of NAbs in the milieu on DC development, we examined the status of DCs in patients with X-linked agammaglobulinemia, a disease characterized by paucity of B cells and circulating antibodies. We demonstrate that the
in vitro
differentiation of DCs is severely impaired in these patients, at least in part because of low levels of circulating NAbs. We identified NAbs reactive with the CD40 molecule as an important component that participates in the development of DCs. CD40-reactive NAbs restored normal phenotypes of DCs in patients. The maturation process induced by CD40-reactive NAbs was accompanied by an increased IL-10 and decreased IL-12 production. The transcription factor analysis revealed distinct signaling pathways operated by CD40-reactive NAbs compared to those by CD40 ligand. These results suggest that B cells promote bystander DC development through NAbs and the interaction between NAbs and DCs may play a role in steady-state migration of DCs.
Direct observation of hole transfer through double-helical DNA over 100 Å
Authors: Takada Tadao , Kawai Kiyohiko , Fujitsuka Mamoru , Majima Tetsuro
Published: September 2004

Mechanism of photo-induced electron transfer and the subsequent hole transfer in DNA has been studied extensively, but so far we are not aware of any reliable report of the observation of the long-distance hole-transfer process. In this article, we demonstrate the results of direct observation for the long-distance hole transfer in double-helical DNA over 100 Å with time-resolved transient absorption measurements. DNA conjugated with naphthalimide (NI) and phenothiazine (PTZ) (which worked as electron-acceptor and donor molecules, respectively) at both 5′ ends was synthesized to observe the hole-transfer process. Site-selective charge injection into G by means of the adenine-hopping process was accomplished by excitation of NI with a 355-nm laser flash. Transient absorption around 400 nm, which was assigned to the NI radical anion, was observed immediately after the irradiation of a laser flash, indicating that the charge separation between NI and the nearest G occurred. Then, the transient absorption of the PTZ radical cation (PTZ
•+
) at 520 nm was emerged, which was attributed to the hole transfer through DNA to the PTZ site. By monitoring the time profiles of the transient absorption of PTZ
•+
for NI-A
6
-(GA)
n
-PTZ and NI-A
6
-(GT)
n
-PTZ (
n
= 2, 3, 4, 6, 8, 12) (base sequences correspond to those for DNA modified with NI), the long-distance hole-transfer process from G to PTZ, which occurred in the time scale of microsecond to millisecond, was observed directly. By assuming an average distance of 3.4 Å between base-pairs, total distance reaches 100 Å for
n
= 12 sequences. Our results clearly show the direct observation of the long-distance hole transfer over 100 Å.
Mutagenesis, genotoxicity, and repair of 1-methyladenine, 3-alkylcytosines, 1-methylguanine, and 3-methylthymine inalkB Escherichia coli
Authors: Delaney James C. , Essigmann John M.
Published: September 2004

AlkB repairs 1-alkyladenine and 3-methylcytosine lesions in DNA by directly reversing the base damage. Although repair studies with randomly alkylated substrates have been performed, the miscoding nature of these and related individually alkylated bases and the suppression of mutagenesis by AlkB within cells have not yet been explored. Here, we address the miscoding potential of 1-methyldeoxyadenosine (m1A), 3-methyldeoxycytidine (m3C), 3-ethyldeoxycytidine (e3C), 1-methyldeoxyguanosine (m1G), and 3-methyldeoxythymidine (m3T) by synthesizing single-stranded vectors containing each alkylated base, followed by vector passage throughEscherichia coli. In SOS–, AlkB-deficient cells, m1A was only 1% mutagenic; however, m3C and e3C were 30% mutagenic, rising to 70% in SOS+cells. In contrast, the mutagenicity of m1G and m3T in AlkB–cells dropped slightly when SOS polymerases were expressed (m1G from 80% to 66% and m3T from 60% to 53%). Mutagenicity was abrogated for m1A, m3C, and e3C in wild-type (AlkB+) cells, whereas m3T mutagenicity was only partially reduced. Remarkably, m1G mutagenicity was also eliminated in AlkB+cells, establishing it as a natural AlkB substrate. All lesions were blocks to replication in AlkB-deficient cells. The m1A, m3C, and e3C blockades were completely removed in wild-type cells; the m1G blockade was partially removed and that for m3T was unaffected by the presence of AlkB. All lesions demonstrated enhanced bypass when SOS polymerases were induced. This work provides direct evidence that AlkB suppresses both genotoxicity and mutagenesis by physiologically realistic low doses of 1-alkylpurine and 3-alkylpyrimidine DNA damagein vivo.
A directed screen for genes involved in
Drosophila
blood cell activation
Authors: Zettervall Carl-Johan , Anderl Ines , Williams Michael J. , Palmer Ruth , Kurucz Eva , Ando Istvan , Hultmark Dan
Published: September 2004

An attack by a parasitic wasp activates a vigorous cellular immune response in
Drosophila
larvae. This response is manifested by an increased number of circulating cells, the hemocytes, and by the appearance of a specialized class of hemocyte, the lamellocytes, which participate in the encapsulation and killing of the parasite. To study the molecular mechanisms of this response, we have overexpressed different genes in the hemocytes, by using the GAL4-upstream activating sequence system and a hemocyte-specific
Hemese-GAL4
driver. Multiple transgenes were tested, representing several important signaling pathways. We found that the proliferation response and the activation of lamellocyte formation are independent phenomena. A drastic increase in the number of circulating hemocytes is caused by receptor tyrosine kinases, such as
Egfr
,
Pvr
, and
Alk
, as well as by the downstream signaling components
Ras85D
and
pointed
, supporting the notion that the Ras–mitogen-activated protein kinase pathway regulates hemocyte numbers. In the case of
Pvr
and
Alk
, this phenotype also is accompanied by lamellocyte formation. By contrast, constitutively active
hopscotch
and
hemipterous
give massive activation of lamellocyte formation with little or no increase in total hemocyte numbers. This finding indicates that both the Jak/Stat and the Jun kinase pathways affect lamellocyte formation. Still other signals, mediated by

aop
ACT

,

Toll
10b

, and
Rac1
expression, cause a simultaneous increase in lamellocyte and total cell numbers, and the same effect is seen when WNT signaling is suppressed. We conclude that the activation of a cellular response is complex and affected by multiple signaling pathways.
Parallel inactivation of multipleGALpathway genes and ecological diversification in yeasts
Authors: Hittinger Chris Todd , Rokas Antonis , Carroll Sean B.
Published: September 2004

Understanding the evolutionary relationship between genome content and ecological niche is one of the fundamental challenges of biology. The distinct physiologies of yeast species provide a window into how genomes evolve in concert with niche. Although the enzymes of the well studied yeast galactose utilization pathway are present in all domains of life, we have found that multiple genes of theGALpathway are absent from four yeast species that cannot use galactose. Whereas three species lack any trace of the pathway except a single gene,Saccharomyces kudriavzevii, a close relative ofSaccharomyces cerevisiae, retains remnants of all seven dedicatedGALgenes as syntenic pseudogenes, providing a rare glimpse of an entire pathway in the process of degeneration. An estimate of the timing of gene inactivation suggests that pathway degeneration began early in the lineage and proceeded rapidly.S. kudriavzeviiexhibits several other divergent physiological properties that are associated with a shift in ecological niche. These results suggest that rapid and irreversible gene inactivation and pathway degeneration are associated with adaptation to new ecological niches in natural populations. Inactivated genes may generally serve as markers of specific functions made dispensable by recent adaptive shifts.
Prevention of type I diabetes transfer by glutamic acid decarboxylase 65 peptide 206-220-specific T cells
Authors: Kim Seon-Kyeong , Tarbell Kristin V. , Sanna Maija , Vadeboncoeur Mary , Warganich Tibor , Lee Mark , Davis Mark , McDevitt Hugh O.
Published: September 2004

Glutamic acid decarboxylase (GAD) 65 is one of the major pancreatic antigens targeted by self-reactive T cells in type I diabetes mellitus. T cells specific for GAD65 are among the first to enter inflamed islets and may be important for the initiation of autoimmune diabetes. However, we previously reported that nonobese diabetic (NOD) mice transgenic for a T cell antigen receptor (TCR) specific for one of the immunodominant epitopes of GAD65, peptide 286-300 (G286), are protected from insulitis and diabetes. To examine whether other GAD65-reactive T cells share this phenotype, we have generated TCR transgenic NOD mice for a second immunodominant epitope of GAD65, peptide 206-220 (G206). As in G286 mice, G206 mice do not develop islet inflammation or diabetes. When adoptively transferred along with diabetogenic T cells, activated G206 T cells significantly delayed the onset of diabetes in NOD.scidrecipients. Both G206 and G286 T cells produce immunoregulatory cytokines IFN-γ and IL-10 at low levels when activated by cognate antigens. These data suggest that GAD65-specific T cells may play a protective role in diabetes pathogenesis by regulating pathogenic T cell responses. A better understanding of the functions of autoreactive T cells in type I diabetes will be necessary for choosing desirable targets for immunotherapy.
Amygdala stimulation modulates hippocampal synaptic plasticity
Authors: Nakao Kazuhito , Matsuyama Koji , Matsuki Norio , Ikegaya Yuji
Published: September 2004

Experience-dependent synaptic plasticity is a fundamental feature of neural networks involved in the encoding of information, and the capability of synapses to express plasticity is itself activity-dependent. Here, we introduce a “low-frequency burst stimulation” protocol, which can readily induce both long-term potentiation (LTP) and long-term depression (LTD) at
in vivo
medial perforant path–dentate gyrus synapses. By varying stimulation parameters, we were able to build a stimulus–response map of synaptic plasticity as a LTP–LTD continuum. The response curve displayed a bidirectional shift toward LTP and LTD, depending on the degree and timing of neural activity of the basolateral amygdala. The range of this plastic modulation was also modified by past activity of the basolateral amygdala, suggesting that the amygdala can arrange its ability to regulate the dentate plastic responses. The effects of the BLA activation were replicated by stimulation of the lateral perforant path and, hence, BLA stimulation may recruit the lateral entorhinal cortex. These results represent a high-order dimension of heterosynaptic modulations of hippocampal synaptic plasticity.
Sword and shield: Linked group B streptococcal β-hemolysin/cytolysin and carotenoid pigment function to subvert host phagocyte defense
Authors: Liu George Y. , Doran Kelly S. , Lawrence Toby , Turkson Nicole , Puliti Manuela , Tissi Luciana , Nizet Victor
Published: September 2004

Group BStreptococcus(GBS) is a major cause of pneumonia, bacteremia, and meningitis in neonates and has been found to persist inside host phagocytic cells. The pore-forming GBS β-hemolysin/cytolysin (βH/C) encoded bycylEis an important virulence factor as demonstrated in severalin vivomodels. Interestingly,cylEdeletion results not only in the loss of βH/C activity, but also in the loss of a carotenoid pigment of unknown function. In this study, we sought to define the mechanism(s) by whichcylEmay contribute to GBS phagocyte resistance and increased virulence potential. We found thatcylE-deficient GBS was more readily cleared from a mouse's bloodstream, human whole blood, and isolated macrophage and neutrophil cultures. Survival was linked to the ability of βH/C to induce cytolysis and apoptosis of the phagocytes. At a lower bacterial inoculum,cylEalso contributed to enhanced survival within phagocytes that was attributed to the ability of carotenoid to shield GBS from oxidative damage. In oxidant killing assays,cylEmutants were shown to be more susceptible to hydrogen peroxide, hypochlorite, superoxide, and singlet oxygen. Together, these data suggest a mechanism by which the linkedcylE-encoded phenotypes, βH/C (sword) and carotenoid (shield), act in partnership to thwart the immune phagocytic defenses.
Responsive transporter genes within the murine intestinal-pancreatic axis form a basis of zinc homeostasis
Authors: Liuzzi Juan P. , Bobo Jeffrey A. , Lichten Louis A. , Samuelson Don A. , Cousins Robert J.
Published: September 2004

Zn homeostasis in animals is a consequence of avid uptake and retention, except during conditions of limited dietary availability, and/or factors such as parasites, which compete for this micronutrient or compromise retention by the host. Membrane proteins that facilitate Zn transport constitute the SLC30A (ZnT) and SLC39A (Zip) gene families. Because dietary recommendations are based on the balance between intestinal absorption and endogenous losses, we have studied Zn transporter expression of the murine intestinal-pancreatic axis to identify transporters that are likely to be involved in homeostatic control of Zn metabolism. Marked tissue specificity of expression was observed in Zn-depleted vs. Zn-adequate mice. As shown by quantitative PCR, Western blot analysis, and immunohistochemistry, intestinal Zip4 was markedly up-regulated in response to Zn-depletion conditions. The increased abundance of Zip4 is concentrated at the apical membrane of enterocytes. There are 16 ZnT and Zip transporters expressed in pancreas. Only two, ZnT1 and ZnT2 (both cellular Zn exporters), show a progressive down-regulation under Zn-depleted conditions. In Zn-adequate mice, ZnT1 is diffusely distributed in acinar cell cytoplasm and colocalizes with α-amylase but is not detected in pancreatic islets. In acinar cells during Zn depletion, ZnT1 is localized to the plasma membrane. Intestinal Zip4 up-regulation by Zn-depletion conditions is dampened in metallothionein knockout mice, suggesting that intracellular Zn pools influence these responses. The results show that Zn transporter expression in the intestinal-pancreatic axis is a component of the homeostatic regulation of this micronutrient.
Testing the Global City-Social Polarisation Thesis: Hong Kong since the 1990s
Authors: Chiu Stephen W. K. , Lui Tai-lok
Published: September 2004

The literature on the development of global cities suggests that Hong Kong had qualified as a global city by the early 1990s. Using data from the Population Censuses, this paper documents the extent to which the process of social polarisation accompanied Hong Kong's globalisation. As predicted by the global city literature, Hong Kong experienced during the 1990s a process of occupational polarisation and widening income inequality as a result of its transformation from an industrial colony to a producer service-driven global city. The paper outlines the gender dimension in this polarisation process, and how the forces of migration contributed to the reshaping of the social structure so that it now resembles an 'hour-glass'. The findings largely support Sassen's hypotheses regarding the social consequences of global city development, but the paper also highlights the effect of local institutional contexts in mediating the impact of global forces.
'Best Places': Interurban Competition, Quality of Life and Popular Media Discourse
Authors: McCann Eugene J.
Published: September 2004

This paper explores relationships between the politics of urban competitiveness and popular media discourse about the 'good life' and 'good places'. Specifically, it focuses on the influence of popular 'best places to live' rankings on urban policy in three US cities. It addresses two issues: how and why similar policies are transferred from place to place; and, how 'extra-economic' factors are mobilised in formulating local economic development policy. It argues that the media's role in these processes is understudied and that its normative discourse is powerful and political. This argument is influenced by and illustrative of a recent attempt to locate the study of discursive power much more centrally in political economy approaches to urban studies.
The Impact of Cultural Events on City Image: Rotterdam, Cultural Capital of Europe 2001
Authors: Richards Greg , Wilson Julie
Published: September 2004

Cities are increasingly using cultural events to improve their image, stimulate urban development and attract visitors and investment. As part of its event-led regeneration strategy, Rotterdam staged the 'Cultural Capital of Europe' event in 2001. The aims were to attract visitors and to stimulate cultural consumption among residents, while positioning Rotterdam as a cultural destination. Over 2000 questionnaire responses by resident and non-resident visitors to the Cultural Capital event were used to evaluate the image effects of the event. In depth interviews were also undertaken with policy-makers and cultural managers, to permit evaluation of survey findings in the context of richer qualitative material. The image of the city as a cultural destination did improve in 2001, but the physical and tangible elements of the city's image (modern architecture, water) and its character as the working city of the Netherlands continued to dominate.
Post-industrialism, Post-modernism and the Reproduction of Vancouver's Central Area: Retheorising the 21st-century City
Authors: Hutton Thomas A.
Published: September 2004

Planning and local policies, informed recurrently by theories of transformative urban development, have represented influential (and at times decisive) agencies of change in Vancouver's metropolitan core. A commitment to principles of post-industrialism in the 1970s, realised through the conversion of False Creek South from an obsolescent industrial site to a medium-density, mixed-income residential landscape, effectively broke the mould of the mid-century urban core. The seminal Central Area Plan (approved 1991) enabled the comprehensive reordering of inner-city space, exemplified by a post-modern diversity, complexity and interdependency of territory and land use, and a strategic reversal of the employment-housing imbalance in the core. The city has broadly succeeded in asserting public interests as contingencies of change within the core, but these processes have created new social conflicts, tensions and displacements, as well as a glittering and paradigmatic 21st-century central city. In theoretical terms, the Vancouver experience marks a clear break from the classic model of the post-industrial city, the latter typified by a monocultural, office-based economy, extreme spatial asymmetries of investment and development and modernist form and imagery. At the same time, emergent production clusters, residential mega-projects and spaces of consumption and spectacle in the central area present marked contrasts to the spatial disorder and chaotic patterns of `incipient' post-modernism, underscoring an exigent need for innovative and integrative retheorisation.
Estimating the Public Good Value of Preserving a Local Historic Landmark: The Role of Non-substitutability and Citizen Information
Authors: Kling Robert W. , Revier Charles F. , Sable Karin
Published: September 2004

This study applies stated-preference methods to estimate the public good values of preservation and restoration of a local historic landmark in a medium-sized US city. The survey device centres on a referendum-style dichotomous-choice question regarding city participation in a restoration partnership. Use of a double-split sample allows analysis of the effect on valuation of both heritage information and willingness-to-pay versus willingness-to-accept constructs, where the latter is approached by the method of paired comparison, allowing a non-substitutability effect to be separated from any endowment effect. Econometric analysis using a standard binary logit model indicates the existence of a strong non-substitutability effect and a significant information effect that further suggests the importance of non-substitutability in valuation.
Understanding How Land is Exchanged: Co-ordination Mechanisms and Transaction Costs
Authors: Needham Barrie , de Kam George
Published: September 2004

This paper seeks to increase our understanding of how land is exchanged between suppliers and demanders. Most current land-price theories, and the land-use models which are derived from them, assume that co-ordination between suppliers and demanders is achieved through the price mechanism. There are, however, other possible co-ordination mechanisms, including imposed rules and mutual trust. In order to take account of these, the effect of institutions has to be included in the theories. Transaction cost economics, as one strand of institutional economics, seeks to explain which co-ordination mechanism is chosen in practice. In this paper, the application of these ideas is illustrated with findings from a detailed survey of how Dutch housing associations acquire land. It appears that these housing associations choose to acquire land through the mechanism of mutual trust when there is a network in place which they can use, and to acquire through the market when that mechanism is not available. This application shows how the theoretical ideas can be operationalised and tested in practice. If this were done more widely, the assumption that price is the main co-ordination mechanism could be tested critically. The outcome would be important not only for land-price theory, but also for land-use policy.
Building social capital in early childhood education and care: an Australian study
Authors: Farrell Ann , Tayler Collette , Tennent Lee
Published: September 2004

Mounting research evidence demonstrates that effective ‘early childhood education and care’ (ECEC) has short‐term and longer‐term social and educational benefits for children and families. An allied body of evidence attests to the contribution of social capital (i.e. social networks and relationships based on trust) to such benefits. The research reported in this article bridges these two bodies of evidence by researching the social capital of children, their families and community members in the context of a state‐wide initiative (in Queensland, Australia) of integrated early childhood and family hubs. Drawn conceptually from the sociology of childhood, a methodological feature of the research is a broadened focus on children, not just adults, as reliable informants of their own everyday experience in ECEC. Some 138 children (aged 4–8 years) in urban and rural/remote localities in Queensland participated in research conversations about their social experience in and beyond ECEC. Children's social capital was found to be higher in the urban community than in the rural community, highlighting the potential of child and family hubs to strengthen children's social capital in those communities with few social facilities.
Using baseline assessment data to make international comparisons
Authors: Tymms Peter , Merrell Christine , Jones Paul
Published: September 2004

International studies have concentrated on the achievements of children during or at the end of their schooling. But such data are difficult to interpret without knowing the progress that they have made since they started school. This article argues that the time has come to study the starting points of children as they begin their education. Such a study is doubtless difficult to design and this study reports an analysis of data from a baseline assessment carried out with thousands of children starting school in very different circumstances, with different languages and cultures and in different countries. It is a pilot international study. Although difficulties are exposed the analyses indicate that such a study is now possible and, it is argued, should be carried out.
The impact of pre‐school on young children's cognitive attainments at entry to reception
Authors: Sammons Pam , Elliot Karen , Sylva Kathy , Melhuish Edward , Siraj‐Blatchford Iram , Taggart Brenda
Published: September 2004

This article explores the impact of pre‐school experience on young children's cognitive attainments at entry to primary school and analyses data collected as part of a wider longitudinal study, the Effective Provision of Pre‐school Education (EPPE) project, which followed a large sample of young children attending 141 pre‐school centres drawn from six types of provider in five English regions. The article compares the characteristics and attainments of the pre‐school sample with those of an additional ‘home’ sample (children who had not attended pre‐school) recruited at entry to reception. Multilevel analyses of relationships between child, parent and home environment characteristics and children's attainments in pre‐reading, early number concepts and language skills are presented. Duration of time in pre‐school is found to have a significant and positive impact on attainment over and above important influences such as family socio‐economic status, income, mother's qualification level, ethnic and language background. The research also points to the separate and significant influence of the home learning environment. It is concluded that pre‐school can play an important part in combating social exclusion by offering disadvantaged children, in particular, a better start to primary school.
Unstructured youth recreation centre participation and antisocial behaviour development: Selection influences and the moderating role of antisocial peers
Authors: Mahoney Joseph L. , Stattin Håkan , Lord Heather
Published: September 2004

This study involves a two-year longitudinal investigation of adolescent participation in unstructured youth recreation centres and the development of antisocial behaviour. Participants were 1163 adolescents who represented 92% of all eighth-grade students in the town of Örebro, Sweden, during the fall of 1999. Antisocial young people and those with poor relations to parents or school were likely to become involved in the centres. After controlling for these selection influences, the frequency of youth centre participation was associated with a significant increase in antisocial behaviour over time for boys and girls. Youth centres that aggregated many antisocial peers together were particularly likely to promote the antisocial behaviour of new attendees. The findings are consistent with prior theory and research on youth development and out-of-school activities. Activities that lack structure and skill-building aims appear to attract high-risk adolescents and the resulting social environment is conducive to the development of antisocial behaviour.
Conformational changes in CLIP-170 regulate its binding to microtubules and dynactin localization
Authors: Lansbergen Gideon , Komarova Yulia , Modesti Mauro , Wyman Claire , Hoogenraad Casper C. , Goodson Holly V. , Lemaitre Régis P. , Drechsel David N. , van Munster Erik , Gadella Theodorus W.J. , Grosveld Frank , Galjart Niels , Borisy Gary G. , Akhmanova Anna
Published: September 2004

Cytoplasmic linker protein (CLIP)-170, CLIP-115, and the dynactin subunit p150Glued are structurally related proteins, which associate specifically with the ends of growing microtubules (MTs). Here, we show that down-regulation of CLIP-170 by RNA interference results in a strongly reduced accumulation of dynactin at the MT tips. The NH2 terminus of p150Glued binds directly to the COOH terminus of CLIP-170 through its second metal-binding motif. p150Glued and LIS1, a dynein-associating protein, compete for the interaction with the CLIP-170 COOH terminus, suggesting that LIS1 can act to release dynactin from the MT tips. We also show that the NH2-terminal part of CLIP-170 itself associates with the CLIP-170 COOH terminus through its first metal-binding motif. By using scanning force microscopy and fluorescence resonance energy transfer-based experiments we provide evidence for an intramolecular interaction between the NH2 and COOH termini of CLIP-170. This interaction interferes with the binding of the CLIP-170 to MTs. We propose that conformational changes in CLIP-170 are important for binding to dynactin, LIS1, and the MT tips.