bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of an EU protocol for the detection and diagnosis of Potato spindle tuber pospiviroid*
Authors: Jeffries C. , James C. 
Published: May 2005

The work described here formed part of the EU SMT DIAGPRO project, to develop diagnostic protocols for 18 regulated pests. The Potato spindle tuber pospiviroid (PSTVd) protocol was developed primarily for testing in vitro‐ and glasshouse‐grown potato plants for the purposes of post‐entry quarantine and the production of pathogen‐tested nuclear stock. After a performance audit of methods used by 12 laboratories in Europe and America by ring testing, four methods were chosen for multilaboratory validation. For most laboratories, the detection limits were 10–20 mg of PSTVd‐infective tissue for R‐PAGE; 0.25–0.5 mg for DIG‐probe; 0.062 mg for RT‐PCR; and 0.0155 mg for TaqMan (this was the lowest weight of infective tissue tested). Some laboratories were able to extend the detection limit to 0.0155 mg for DIG‐probe and RT‐PCR. The DIG‐probe and R‐PAGE are recommended as primary detection methods, with confirmation of viroid presence by any of the four validated detection methods. Specific diagnosis requires the viroid to be sequenced. Other methods may be used for primary detection, providing that they preferably detect all PSTVd isolates and other Pospiviroids that have the potential to infect potato, and detect viroid in at least 1/10 of the tissue weight normally tested per plant.
The dynamics of landscape change and snow geese in mid‐continent North America
Authors: Abraham Kenneth F. , Jefferies Robert L. , Alisauskas Ray T. 
Published: May 2005

AbstractThe Mid‐Continent Population of the lesser snow goose, which breeds in the eastern and central Canadian Arctic and sub‐Arctic, and winters in the southern United States and northern Mexico has increased 5–7% annually from the late 1960s to the mid‐1990s, largely because of increased survival in response to an agricultural food subsidy. The rise in numbers complements the increased use of nitrogen fertilizers and a corresponding rise in yields of rice, corn, and wheat along the flyways and on the wintering grounds. In sub‐Arctic migration areas and at Arctic breeding colonies, foraging by high numbers of birds has led to loss of coastal vegetation, adverse changes in soil properties and the establishment of an alternative stable state of exposed sediment, which can be detected with LANDSAT imagery. At a local scale, gosling growth, size and survival decreased in affected areas and other taxa have been adversely affected. The food subsidy on wintering and migration areas appears insufficient to meet reproductive demands as foraging in spring continues to occur on southern Hudson Bay staging and nesting areas. The recent introduction of liberal hunting regulations may reduce population size in the near term, but the revegetation of these coastal ecosystems will take decades to achieve. The present pattern of vegetation loss in these Arctic coastal systems is likely to continue in the forseeable future.
Climate change and the fate of cereal aphids in Southern Britain
Authors: Newman J. A. 
Published: May 2005

AbstractClimate change will drive dramatic changes in the abundance and distribution of species. Assessing the impacts of climate change on our agricultural systems is essential for mitigation planning. Here, I combine projections from the UK Hadley Centre's HadRM03 climate change model for Southern Britain with a general mechanistic model of the interaction between climate, temperate grass physiology and cereal aphid population dynamics. Aphids are one of the largest and most important groups of crop pests and disease vectors worldwide but particularly in temperate regions. The model predicts an increasingly dramatic decline in cereal aphid abundance from the 1961 to 1990 baseline with increasing CO2 emissions: low emissions=−5%, medium low=−12%, medium high=−61%, and high=−92%. Of the six climate variables used in the model, changes in temperature and rainfall were the most important across all emissions scenarios and, counter‐intuitively, the direct impact of elevated CO2 actually declines as emissions increase. The results suggest that the pest status of cereal aphids in Southern Britain will significantly decline by the end of this century.
Diurnal, seasonal and annual variation in the net ecosystem CO2 exchange of a desert shrub community (Sarcocaulescent) in Baja California, Mexico
Authors: Hastings Steven J. , Oechel Walter C. , Muhlia‐Melo Arturo 
Published: May 2005

AbstractEstimates of net ecosystem exchange (NEE) of CO2 have been measured on a variety of ecosystems world wide including grasslands, savannahs, boreal, pine, deciduous, Mediterranean and tropical rain forests as well as arctic tundra. While there have been numerous comparisons between net primary productivity of arid and semiarid grasslands and shrublands, notably lacking are estimates of NEE with a few exceptions. The objective of this study was to characterize the seasonal and annual carbon flux of a desert shrub ecosystem using the eddy covariance technique to determine the sensitivity of the system to the timing and varying amounts of precipitation. Measurements began in July of 2001, a year with 339 mm of rainfall, considerably above the long‐term average of 174 mm and preceded by 2 years of below average rainfall (50–62 mm). Over the 2 complete years of measurements, precipitation was 147 and 197 mm in 2002 and 2003, respectively. In all years, the majority of the precipitation fell between August and September. The site was a sink of −39 g C m−2 yr−1 in 2002 with a relatively strong uptake in the early part of the year and reduced uptake after the suboptimal rainfall in September. This contrasts with 2003 when the ecosystem took up −52 g C m−2 yr−1 concentrated in the fall after significant rain in August and September. Likely, extremely low rainfall years would result in a carbon loss while a strengthening of the typical winter secondary peak in precipitation (notably absent in the 2 years of measurements) may extend uptake into the spring resulting in more carbon accumulation. The system appears to be buffered against variations in annual rainfall attributed to water storage in the stems and roots.
Aboveground Forest Biomass and the Global Carbon Balance
Authors: Houghton R. A. 
Published: May 2005

AbstractThe long‐term net flux of carbon between terrestrial ecosystems and the atmosphere has been dominated by two factors: changes in the area of forests and per hectare changes in forest biomass resulting from management and regrowth. While these factors are reasonably well documented in countries of the northern mid‐latitudes as a result of systematic forest inventories, they are uncertain in the tropics. Recent estimates of carbon emissions from tropical deforestation have focused on the uncertainty in rates of deforestation. By using the same data for biomass, however, these studies have underestimated the total uncertainty of tropical emissions and may have biased the estimates. In particular, regional and country‐specific estimates of forest biomass reported by three successive assessments of tropical forest resources by the FAO indicate systematic changes in biomass that have not been taken into account in recent estimates of tropical carbon emissions. The ‘changes’ more likely represent improved information than real on‐the‐ground changes in carbon storage. In either case, however, the data have a significant effect on current estimates of carbon emissions from the tropics and, hence, on understanding the global carbon balance.
Leaf litter production and decomposition in a poplar short‐rotation coppice exposed to free air CO2 enrichment (POPFACE)
Authors: Cotrufo M. Francesca , De Angelis Paolo , Polle Andrea 
Published: May 2005

AbstractThe capacity of forest ecosystems to sequester C in the soil relies on the net balance between litter production above, as well as, below ground, and decomposition processes. Nitrogen mineralization and its availability for plant growth and microbial activity often control the speed of both processes. Litter production, decomposition and N mineralization are strongly interdependent. Thus, their responses to global environmental changes (i.e. elevated CO2, climate, N deposition, etc.) cannot be fully understood if they are studied in isolation. In the present experiment, we investigated litter fall, litter decomposition and N dynamics in decomposing litter of three Populus spp., in the second and third growing season of a short rotation coppice under FACE. Elevated CO2 did not affect annual litter production but slightly retarded litter fall in the third growing season. In all species, elevated CO2 lowered N concentration, resulting in a reduction of N input to the soil via litter fall, but did not affect lignin concentrations. Litter decomposition was studied in bags incubated in situ both in control and FACE plots. Litter lost between 15% and 18% of the original mass during the eight months of field incubation. On average, litter produced under elevated CO2 attained higher residual mass than control litter. On the other end, when litter was incubated in FACE plots it exhibited higher decay rates. These responses were strongly species‐specific. All litter increased their N content during decomposition, indicating immobilization of N from external sources. Independent of the initial quality, litter incubated on FACE soils immobilized less N, possibly as a result of lower N availability in the soil. Indeed, our results refer to a short‐term decomposition experiment. However, according to a longer‐term model extrapolation of our results, we anticipate that in Mediterranean climate, under elevated atmospheric CO2, soil organic C pool of forest ecosystems may initially display faster turnover, but soil N availability will eventually limit the process.
The North Atlantic Oscillation and regional phenology prediction over Europe
Authors: Cook Benjamin I. , Smith Thomas M. , Mann Michael E. 
Published: May 2005

AbstractWe present an integrated modeling study designed to investigate changes in ecosystem level phenology over Europe associated with changes in climate pattern, by the North Atlantic Oscillation (NAO). We derived onset dates from processed NDVI data sets and used growing degree day (GDD) summations from the NCEP re‐analysis to calibrate and validate a phenology model to predict the onset of the growing season over Europe. In a cross‐validation hindcast, the model (PHENOM) is able to explain 63% of the variance in onset date for grid cells containing at least 50% mixed and boreal forest. Using a model developed from previous work we performed climate change scenarios, generating synthetic temperature and GDD distributions under a hypothetically increasing NAO. These new distributions were used to drive PHENOM and project changes in the timing of onset for forested cells over Europe. Results from the climate change scenarios indicate that, if the current trend in the NAO continues, there is the potential for a continued advance to the start of the growing season by as much as 13 days in some areas.
Disrupting the melanin‐concentrating hormone receptor 1 in mice leads to cognitive deficits and alterations of NMDA receptor function
Authors: Adamantidis Antoine , Thomas Elizabeth , Foidart Agnès , Tyhon Amélie , Coumans Bernard , Minet Arlette , Tirelli Ezio , Seutin Vincent , Grisar Thierry , Lakaye Bernard 
Published: May 2005

AbstractIn order to investigate the physiological properties of the melanin‐concentrating hormone (MCH) we have generated and used mice from which the MCH receptor 1 gene was deleted (MCHR1Neo/Neo mice). Complementary experimental approaches were used to investigate alterations in the learning and memory processes of our transgenic model. The ability of the knockout strain to carry out the inhibitory passive avoidance test was found to be considerably impaired although no significant differences were observed in anxiety levels. This impaired cognitive property prompted us to explore modifications in N‐methyl d‐aspartate (NMDA) responses in the hippocampus. Intracellular recordings of CA1 pyramidal neurons in hippocampal slices from the MCHR1Neo/Neo mice revealed significantly decreased NMDA responses. Finally, using in situ hybridization we found a 15% reduction in NMDAR1 subunit in the CA1 region. These results show for the first time a possible role for MCH in the control of the function of the NMDA receptor.
Up‐regulation of β2 and α7 subunit containing nicotinic acetylcholine receptors in mouse striatum at cellular level
Authors: Pakkanen Jukka S. , Jokitalo Eija , Tuominen Raimo K. 
Published: May 2005

AbstractNicotine releases dopamine in the brain by activating neuronal nicotinic acetylcholine receptors (nAChRs). Chronic nicotine treatment increases the number of nAChRs, which represents plasticity of the brain. Together these phenomena have been suggested to have a role in the development of nicotine addiction. In the brain nAChRs can be localized synaptically, extrasynaptically or intracellularly. The purpose of these studies was to clarify the effects of chronic nicotine treatment on the localization of β2 and α7 nAChR subunits in brain areas involved in nicotine addiction. Nicotine was administered orally in drinking water to male NMRI mice for 7 weeks. At the end of chronic nicotine treatment the localization of the nAChR subunits was studied in the dorsal striatum and in the ventral tegmental area (VTA) by using electron microscopy. In the brain areas studied β2 and α7 subunits were localized presynaptically and postsynaptically in axon endings and in dendrites. In both areas the majority of the β2 and α7 subunits were localized at extrasynaptic sites. In response to chronic nicotine treatment the β2 and α7 nAChR subunit labelling was increased at synaptic and extrasynaptic sites as well as intracellularly. This suggests that the trafficking of nAChR subunits is increased as a result of chronic nicotine treatment and nAChRs in all parts of neurons could have functional roles in the formation of nicotine addiction.
Effects of exposure to a predator on behaviour and serotonergic neurotransmission in different brain regions of C57bl/6N mice
Authors: Beekman Marjolein , Flachskamm Cornelia , Linthorst Astrid C. E. 
Published: May 2005

AbstractClinical studies and animal models have provided evidence that stress and serotonin may play a role in the aetiology of psychiatric diseases such as depression and anxiety. In addition, reciprocal interactions between stress and serotonergic neurotransmission have been demonstrated. However, the relationships between stress, serotonin and behaviour are far from completely understood. In this integrative study, we aimed to elucidate the effect of the psychological stress model predator exposure on behaviour and serotonergic neurotransmission in mice. We used a high time‐resolution microdialysis method to measure extracellular levels of serotonin (5‐hydroxytryptamine, 5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) in the hippocampus, prefrontal cortex, lateral septum and caudate putamen of C57bl/6N mice, before (08:30–10:30 h), during (10:30–11:00 h) and after exposure (11:00–14:00 h) to a rat. Detailed behavioural observations were also made. Rat exposure resulted in behavioural activation, with predominant risk‐assessment activities, and in increases in hippocampal, cortical, septal but not striatal 5‐HT and 5‐HIAA. When rat exposure was repeated on the consecutive day, small behavioural differences and reductions in 5‐HIAA levels, but no differences in the 5‐HT response, as compared with the first exposure were observed. As increases in 5‐HT often coincide with behavioural activation, it was particularly interesting to find that 5‐HT also increased in periods when mice only made minor movements such as sniffing, and that an effect of predator stress was absent in the caudate putamen. Our results indicate that the presence of the rat leads to differential activation of serotonergic neurotransmission in higher brain structures, probably involved in the coping response to this potentially life‐threatening situation.
Oxygen consumption and mitochondrial membrane potential indicate developmental adaptation in energy metabolism of rat cortical neurons
Authors: Schuchmann Sebastian , Buchheim Katharina , Heinemann Uwe , Hosten Norbert , Buttgereit Frank 
Published: May 2005

AbstractNeuronal energy needs are mainly covered via mitochondrial oxidative phosphorylation. Even if the energy supply appears identical in immature and adult brain, nevertheless quantitative differences exist. The present study focuses on the adaptations in cellular energy metabolism caused by the neuronal maturation. As main parameters of oxidative phosphorylation, cellular oxygen consumption and mitochondrial membrane potential were measured in isolated rat cortical cells using a Clark‐type oxygen electrode and microfluorometric techniques. In four age groups (E18–P2, P8–P12, P16–P20, ≥ P28), unstimulated neurons showed a significant age‐dependent increase in basal oxygen consumption (6.1 up to 10.2 nm/min/107 cells). The excitatory neurotransmitter glutamate induced a further, but age‐ and concentration‐independent, elevation of oxygen consumption to a plateau ≥ 14 nm/min/107 cells and a complete depolarization of mitochondrial membrane in neurons ≥ P8. Stimulation using K+ (5–50 mm) effected a concentration‐ and age‐dependent increase in oxygen consumption, but a similar nearby complete depolarization of mitochondrial membrane in all tested age groups. Furthermore, uncoupling mitochondrial membrane function followed by a complete depolarization of mitochondrial membrane showed a maximal oxygen consumption (14–15 nm/min/107 cells) only in neurons ≥ P8. These data suggest that developing and adult cortical neurons cover their increased need of energy following stimulation by an efficiency improvement of mitochondrial oxidative phosphorylation. The age‐independent limited capacity of mitochondrial oxidative phosphorylation, however, causes a reduction in cellular energy disposal in mature neurons and therefore may play a critical role in the increased sensitivity of adult neurons against excitotoxicity and ischaemia.
ΔFosB accumulates in a GABAergic cell population in the posterior tail of the ventral tegmental area after psychostimulant treatment
Authors: Perrotti Linda I. , Bolaños Carlos A. , Choi Kwang‐Ho , Russo Scott J. , Edwards Scott , Ulery Paula G. , Wallace Deanna L. , Self David W. , Nestler Eric J. , Barrot Michel 
Published: May 2005

AbstractThe transcription factor ΔFosB is induced in the nucleus accumbens and dorsal striatum by chronic exposure to several drugs of abuse, and increasing evidence supports the possibility that this induction is involved in the addiction process. However, to date there has been no report of ΔFosB induction by drugs of abuse in the ventral tegmental area (VTA), which is also a critical brain reward region. In the present study, we used immunohistochemistry to demonstrate that chronic forced administration of cocaine induces ΔFosB in the rat VTA. This induction occurs selectively in a γ‐aminobutyric acid (GABA) cell population within the posterior tail of the VTA. A similar effect is seen after chronic cocaine self‐administration. Induction of ΔFosB in the VTA occurs after psychostimulant treatment only: it is seen with both chronic cocaine and amphetamine, but not with chronic opiates or stress. The expression of ΔFosB appears to be mediated by dopamine systems, as repeated administration of a dopamine uptake inhibitor induced ΔFosB in the VTA, while administration of serotonin or norepinephrine uptake inhibitors failed to produce this effect. Time course analysis showed that, following 14 days of cocaine administration, ΔFosB persists in the VTA for almost 2 weeks after cocaine withdrawal. This accumulation and persistence may account for some of the long‐lasting changes in the brain associated with chronic drug use. These results provide the first evidence of ΔFosB induction in a discrete population of GABA cells in the VTA, which may regulate the functioning of the brain's reward mechanisms.
Fucoidan inhibits cellular and neurotoxic effects of β‐amyloid (Aβ) in rat cholinergic basal forebrain neurons
Authors: Jhamandas Jack H. , Wie Myung Bok , Harris Kim , MacTavish David , Kar S. 
Published: May 2005

AbstractThe deposition of β‐amyloid protein (Aβ), a 39–43 amino acid peptide, in the brain and a loss of cholinergic neurons in the basal forebrain are pathological hallmarks of Alzheimer's disease (AD). Seaweeds consumed in Asia contain Fucoidan, a sulfated polysaccharide. Fucoidan has been known to exhibit various biological actions, such as an anti‐inflammatory and antioxidant action. In this study, using whole‐cell patch clamp recordings we examined the effects of Fucoidan on Aβ‐induced whole‐cell currents in acutely dissociated rat basal forebrain neurons. We further investigated whether Fucoidan is capable of blocking Aβ neurotoxicity in primary neuronal cultures. In dissociated cells, bath application of Aβ25−35 (1 µm) caused a reduction of the whole‐cell currents by 16%. Fucoidan, in a dose‐dependent manner, blocks the Aβ25−35 reduction of whole‐cell currents. Exposure of Aβ25−35 (20 µm) or Aβ1−42 (20 µm) to rat cholinergic basal forebrain cultures for 48 h resulted in 40–60% neuronal death, which was significantly decreased by pretreatment of cultures with Fucoidan (0.1–1.0 µm). Fucoidan also attenuated Aβ‐induced down‐regulation of phosphorylated protein kinase C. Aβ1−42‐induced generation of reactive oxygen species was blocked by prior exposure of cultures to Fucoidan. Furthermore, Aβ activation of caspases 9 and 3, which are signaling pathways implicated in apoptotic cell death, is blocked by pretreatment of cultures with Fucoidan. These results show that Fucoidan is able to block Aβ‐induced reduction in whole‐cell currents in basal forebrain neurons and has neuroprotective effects against Aβ‐induced neurotoxicity in basal forebrain neuronal cultures.
Expression of collapsin response mediator proteins 1, 2 and 5 is differentially regulated in newly generated and mature neurons of the adult olfactory system
Authors: Veyrac Alexandra , Giannetti Nathalie , Charrier Emmanuelle , Reymond‐Marron Isabelle , Aguera Michèle , Rogemond Veronique , Honnorat Jérôme , Jourdan François 
Published: May 2005

AbstractCollapsin‐response mediator proteins (CRMPs) are highly expressed in the developing brain where they take part in several aspects of neuronal differentiation. CRMPs are still present postnatally, but their function remains speculative in the adult brain. We studied the expression and localization of CRMP1, CRMP2 and CRMP5 in two areas of the nervous system with persistent neurogenesis in adult mice, the olfactory mucosa and the olfactory bulb. In the olfactory mucosa, we have established that CRMP expression is restricted to postmitotic cells of the olfactory neurons lineage. CRMP5 is coexpressed with growth associated protein of 43 kDa (GAP43) in immature olfactory neurons and is down‐regulated in olfactory marker protein‐positive mature neurons. In contrast, CRMP1 and CRMP2 persist at all stages of differentiation from immature GAP43‐positive to fully mature olfactory neurons. In the olfactory bulb, CRMP1, CRMP2 and CRMP5 are abundant in neuronal progenitors of the subependymal layer and in differentiating interneurons. In both areas, the subcellular distribution of CRMP1 or CRMP2 is different in mature vs. immature neurons, suggesting that these proteins are sequentially involved in various cellular events during neuronal lifetime. The variations of CRMP expression following axotomy are consistent with their differential localization and functional involvement in immature vs. mature neurons of the olfactory system. Our data bring new insight to the putative functions of CRMPs within areas of the adult nervous system with permanent neurogenesis, some related to differentiation of newly generated neurons but others occurring in mature neurons with a limited lifespan.