bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pine mistletoe (Viscum albumssp.austriacum) contributes to Scots pine (Pinus sylvestris) mortality in the Rhone valley of Switzerland
Authors: Dobbertin M. , Rigling A. 
Published: September 2006

SummaryIn recent years unusual high mortality of Scots pine (Pinus sylvestris) has been observed in the Swiss Rhone Valley. The exact causes, however, are not known. At a 2‐ha monitoring plot, tree mortality and crown condition have been monitored since 1996. Between 1996 and 2004, 59% of the Scots pines died, most of them following the drought periods 1996–1998 and 2003–2004, while only 15% of the deciduous trees died. Crown transparency, needle discolouration, dead branch percentage, mistletoe (Viscum albumssp.austriacum) rating,Tomicussp. shoot feeding, male flowering effect, tree stem diameter, crown shading and social tree class assessed in 1998 were used in a logistic regression model to predict tree mortality. Crown transparency, mistletoe rating and percentage of dead branches were found significant in the model and the probability of tree mortality increased with increasing rankings of these parameters. Needle discolouration could be used to substitute ‘dead branch percentage’ as predictor. While crown transparency increased with mistletoe rating, for trees in the same transparency class, trees with medium and heavy mistletoe infection were two to four times more likely to die than trees with no or only low mistletoe infection. For the surviving trees we found that trees with mistletoes showed a significantly higher increase in transparency in the year following a drought than trees without, while in a drought year the opposite was true. At the beginning of the observations no significant differences in transparency had been found between the trees with and without mistletoe. However, by the end of the observation period trees with mistletoe had significantly higher crown transparency. We conclude that mistletoe infection can be considered as both a predisposing factor for tree death, by increasing needle loss following drought and a contributing factor by increasing water stress during drought.
Effects of Mycosphaerella leaf disease on the spectral reflectance properties of juvenile Eucalyptus globulus foliage
Authors: Pietrzykowski E. , Stone C. , Pinkard E. , Mohammed C. 
Published: September 2006

Summary Mycosphaerella leaf disease (MLD) can cause significant discoloration, necrosis and defoliation in commercial plantations of young Eucalyptus globulus. This study investigated the spectral reflectance changes that result in E. globulus foliage from Mycosphaerella infection. Spectral reflectance measurements were made on healthy and infected E. globulus foliage in the visible and near‐infrared wavelengths (400–1000 nm). Reflectance (R) at 760 nm produced the largest difference between the extremes of disease severity classes. The wavelength most sensitive to infection severity was R678 nm. Other sensitive wavelengths were located between 480 and 500 nm. The wavelengths near 708 and 550 nm appeared relatively insensitive to infection severity. The reflectance index best correlated to leaf infection was R678/R550 (r = 0.841, p < 0.0001). This index was used in a linear regression model for successfully predicting leaf infection levels from an independent data set (r = 0.95, p < 0.0001).
The sporicidal activity of yellow‐cedar heartwood, essential oil and wood constituents towards Phytophthora ramorum in culture
Authors: Manter D. K. , Karchesy J. J. , Kelsey R. G. 
Published: September 2006

SummaryIn this paper, we demonstrate that 140 mg/kg of essential oil from the wood of yellow‐cedar, incense cedar, Port‐Orford‐cedar or western juniper strongly inhibits zoospore germination and hyphal growth of Phytophthora ramorum in culture. Four individual compounds in yellow‐cedar heartwood were also tested. Zoospore germination was reduced to 0% with 10, 100 and 1000 mg/kg of nootkatin, carvacrol and valencene, respectively. Nootkatone was the least active compound, with 3.5% zoospore germination at 1000 mg/kg. Sporangia germination was 0% with 500 mg/kg of nootkatin or carvacrol. The disruption of the zoospore outer membrane and the loss of sporangial contents were often observed and indicative of sporicidal activity. Hyphal growth was inhibited by 99.9% with 50 mg/kg of nootkatin or 500 mg/kg of carvacrol, but growth resumed upon removing the inhibitors. The zoosporicidal activity of yellow‐cedar heartwood shavings stored dry for approximately 10 years was consistent with the quantity of extractable compounds they contained. Thus, spreading fresh shavings or chips of yellow‐cedar heartwood with appreciable higher concentrations of the active compounds, over areas in infection zones where spores might be difficult to control such as trails and parking lots used by hikers and bicyclists, might be useful as part of an integrated program to minimize P. ramorum spore distribution.
Records of Bursaphelenchus spp. intercepted in imported packaging wood at Ningbo, China
Authors: Gu J. , Braasch H. , Burgermeister W. , Zhang J. 
Published: September 2006

SummaryFrom January 2003 to June 2005, samples from 3416 batches of wooden packaging material were inspected for the presence of nematodes in the Ningbo Entry–Exit Inspection and Quarantine Bureau, China. Bursaphelenchus spp. were detected in 202 batches from 25 different countries. The following species were identified on the basis of their morphology and their intergenic transcribed spacer‐restriction fragment length polymorphism (ITS‐RFLP) patterns: B. xylophilus, B. fungivorus, B. rainulfi, B. hylobianum, B. thailandae, B. mucronatus, B. aberrans, B. lini, B. singaporensis, B. doui, B. conicaudatus, B. vallesianus, B. pinasteri, B. hofmanni and B. arthuri. The most frequently found species were B. mucronatus (57 batches), B. xylophilus (40 batches), B. fungivorus (21 batches), B. rainulfi (19 batches) and B. thailandae (nine batches). The pine wood nematode B. xylophilus was not only found in packaging wood imported from areas where it is known to occur (i.e. The United States of America, Japan, Korea, Hong Kong and Taiwan), but also from countries considered to be free of this dangerous pest (i.e. Brazil, Thailand, Belgium, The Netherlands, Italy and Spain). The occurrence of B. xylophilus in packaging wood from countries regarded as being free of the nematode can most likely be explained by the global circulation of wooden packaging material among infested and non‐infested countries. Our findings emphasize the need to fully implement international standards on phytosanitary treatment of packaging wood, in order to prevent further spread of the pine wood nematode, and the need for careful re‐examination of the current heat treatment measures.
Investigation of physical and bathymetric characteristics of Lakes Abaya and Chamo, Ethiopia, and their management implications
Authors: Awulachew Seleshi Bekele 
Published: September 2006

AbstractThe purpose of this study was to investigate the physical parameters of Lakes Abaya and Chamo in the Ethiopian rift lakes system, including such physical characteristics as depth, water resources capacity, hydrology, water balances, and impacts of water use and degradation of their watersheds. These parameters have not previously been studied for these two lakes to any significant extent. This study describes the bathymetry survey undertaken for these two lakes, and the morphometric characteristics derived from it. This study is part of a research project developed to provide further details on such parameters as hydrology, water quality, sediment inflows and deposition, lake hydrodynamics and consumptive water uses. The bathymetric survey was conducted, utilizing a combination of global positioning system (GPS) and echo sounder. To calculate the morphometric characteristics, the background lake map was digitized, and the surveyed primary data were developed as digital values. The digital values were interpolated, generating grids of the elevation surface. The elevation area and elevation volume curves (capacity curves) of the two lakes were developed from the digital values, describing the water resources capacity of the lake water basins. The results of this study increase our understanding of the water resources of these two lakes, as well as provide better understanding of their vulnerability to human activities because of their shallow depths. Immediate application of the results, as a basis for continuation of this study, also is highlighted.
A potent non‐monoaminergic paradoxical sleep inhibitory system: a reverse microdialysis and single‐unit recording study
Authors: Crochet Sylvain , Onoe Hirotaka , Sakai Kazuya 
Published: September 2006

AbstractUsing reverse microdialysis and polygraphic recordings in freely moving cats, we investigated the effects on sleep–waking states of application of excitatory and inhibitory amino acid agonists, cholinergic agonist and monoamines to the periaqueductal grey and adjacent mesopontine tegmentum. Single‐unit recordings during behavioural states were further used to determine the neuronal characteristics of these structures. We found that muscimol, a GABAA receptor agonist, induced a significant increase in paradoxical sleep (PS) only when applied to a dorsocaudal central tegmental field (dcFTC) located just beneath the ventrolateral periaqueductal grey. In this structure, both kainic and N‐methyl‐aspartic acids caused a dose‐dependent increase in wakefulness (W) and decrease in both slow‐wave sleep (SWS) and PS. Norepinephrine and epinephrine, and to a lesser extent histamine, also increased W and decreased SWS and PS, whereas serotonin, dopamine and carbachol, a cholinergic agonist, had no effect. Two types of neurones were recorded in this structure, those exhibiting a higher rate of tonic discharge during both W and PS compared with during SWS, and those showing a phasic increase in firing rate during both active W and PS. Both types of neurones showed a gradual increase in unit activity during PS. Our study demonstrated for the first time that the ventrolateral periaqueductal grey and dcFTC play different roles in behavioural state control, that the dcFTC neurones are critically involved in the inhibitory mechanisms of PS generation, playing a central part in its maintenance, and that these neurones are under the control of GABAergic, glutamatergic, adrenergic and histaminergic systems.
Failure of nicotine‐dependent enhancement of synaptic efficacy at Schaffer–collateral CA1 synapses of AD11 anti‐nerve growth factor transgenic mice
Authors: Sola Elisabetta , Capsoni Simona , Rosato‐Siri Marcelo , Cattaneo Antonino , Cherubini Enrico 
Published: September 2006

AbstractAlzheimer's disease is a neurodegenerative disorder characterized by neuronal loss associated with a progressive impairment of cognitive functions. Early consequences of Alzheimer's disease include deficit of cholinergic signalling in particular regions controlling memory processes, such as the cortex and hippocampus, and accumulation of β‐amyloid (Aβ) peptide in neuritic plaques. The cholinergic system depends for its integrity and function on nerve growth factor. Chronic nerve growth factor deprivation in transgenic mice (AD11) engineered to produce recombinant neutralizing anti‐nerve growth factor antibodies leads to progressive age‐dependent Alzheimer's‐like neurodegenerative pathology similar to that found in patients with Alzheimer's disease, associated with a selective loss of cholinergic neurones in the basal forebrain. Here we show that in the hippocampus of 6‐month‐old AD11 mice, Aβ aggregates started appearing in the CA1 region. The accumulation of Aβ was associated with a loss of cholinergic function at CA3–CA1 synapses. Whereas in wild‐type mice nicotine induced a persistent increase of synaptic efficacy via α7 nicotine acetylcholine receptors, in AD11 mice this alkaloid failed to modify synaptic strength. Moreover, nicotine failed to transiently enhance the frequency of spontaneous miniature glutamatergic currents (miniature excitatory postsynaptic currents) recorded from CA1 but not from CA3 pyramidal neurones of AD11 mice. However, in CA3 principal cells of AD11 mice, the potentiating effect of nicotine on miniature excitatory postsynaptic currents was prevented when Aβ peptide 1–42 was added to the extracellular solution. These data suggest that in AD11 mice, Aβ interferes with nicotine acetylcholine receptors at the level of presynaptic glutamatergic terminals, inhibiting their function possibly through calcium signalling via presynaptic α7 nicotine acetylcholine receptors.
Alteration of GABAergic synapses and gephyrin clusters in the thalamic reticular nucleus of GABAA receptor α3 subunit‐null mice
Authors: Studer Remo , Von Boehmer Lotta , Haenggi Tatjana , Schweizer Claude , Benke Dietmar , Rudolph Uwe , Fritschy Jean‐Marc 
Published: September 2006

AbstractMultiple GABAA‐receptor subtypes are assembled from α, β and γ subunit variants. GABAA receptors containing the α3 subunit represent a minor population with a restricted distribution in the CNS. In addition, they predominate in monoaminergic neurons and in the nucleus reticularis thalami (nRT), suggesting a role in the regulation of cortical function and sleep. Mice with a targeted deletion of the α3 subunit gene (α30/0) are viable and exhibit a subtle behavioural phenotype possibly related to dopaminergic hyperfunction. Here, we investigated immunohistochemically the consequences of the loss of α3 subunit for maturation of GABAA receptors and formation of GABAergic synapses in the nRT. Throughout postnatal development, the regional distribution of the α1, α2, or α5 subunit was unaltered in α30/0 mice and the prominent α3 subunit staining of nRT neurons in wildtype mice was not replaced. Subcellularly, as seen by double immunofluorescence, the α3 and γ2 subunit were clustered at postsynaptic sites in the nRT of adult wildtype mice along with the scaffolding protein gephyrin. In α30/0 mice, γ2 subunit clustering was disrupted and gephyrin formed large aggregates localized at the cell surface, but unrelated to postsynaptic sites, indicating that nRT neurons lack postsynaptic GABAA receptors in mutant mice. Furthermore, GABAergic terminals were enlarged and reduced in number, suggesting a partial deficit of GABAergic synapses. Therefore, GABAA receptors are required for gephyrin clustering and long‐term synapse maintenance. The absence of GABAA‐mediated transmission in the nRT may have a significant impact on the function of the thalamo‐cortical loop of α30/0 mice.
Overexpression of a truncated TrkB isoform increases the proliferation of neural progenitors
Authors: Tervonen Topi A. , Ajamian Farzam , De Wit Joris , Verhaagen Joost , Castrén Eero , Castrén Maija 
Published: September 2006

AbstractThe truncated isoform of TrkB, TrkB.T1, has been shown to be expressed in the neurogenic region of rodent brain. TrkB.T1 lacks tyrosine kinase activity and it may modify the action of the full‐length TrkB. We show here that the full‐length TrkB and TrkB.T1 are expressed at the same relative expression levels in mouse neural progenitor cell cultures. The number of neurosphere‐forming progenitors was reduced and apoptosis increased in neurospheres generated from mice overexpressing TrkB.T1 when compared with wild‐type neurospheres. The proliferation of the transgenic neural progenitors was increased, as indicated by the larger average diameter of spheres (140% of control), the increased cell growth in an MTT assay (137% of control) and the faster rate of 3H‐thymidine incorporation (128% of control) in the transgenic cell cultures than in controls. The proliferation of neural progenitors was also increased after lentivirus‐mediated TrkB.T1 overexpression. A significant increase in 3H‐thymidine incorporation (119% of control) and the average diameter of spheres (112% of control) in the TrkB.T1‐transduced neurospheres compared with neurospheres transduced with the control vectors confirmed the role of TrkB.T1 in proliferation of neural progenitor. When induced to differentiate, progenitors overexpressing TrkB.T1 generated two to three times more neurons than did wild‐type cells. The increase in the number of neurons correlated with an increase in the number of apoptotic cells (two‐fold) at these time points. The data indicate that changes in the relative expression levels of different TrkB isoforms influence the replicative capacity of neural progenitors.
Kindling‐induced alterations in GABAA receptor‐mediated inhibition and neurosteroid activity in the rat piriform cortex
Authors: Gavrilovici Cezar , D'Alfonso Sabrina , Dann Mathew , Poulter Michael O. 
Published: September 2006

AbstractThe piriform cortex makes strong interconnections with limbic structures (amygdala, entorhinal cortex and hippocampus) that are involved in memory processing. These connections have also been implicated in the development of temporal lobe epilepsy. However, little is known about how neurones in this region may change during seizure genesis. Here we tested the hypothesis that in the kindling model of temporal lobe epilepsy GABAA receptor‐mediated inhibition is altered in the piriform cortex. To do this we performed whole‐cell patch‐clamp recordings in piriform cortex brain slices obtained from non‐kindled and amygdala‐kindled adult rats. We found that kindling coincided with an increase in the amplitude and duration of miniature inhibitory post‐synaptic currents (mIPSCs) recorded from non‐pyramidal neurones, whereas the mIPSCs occurring on pyramidal (excitatory) cells did not change. Non‐stationary noise analysis of mIPSCs occurring on the non‐pyramidal neurones showed that inferred unitary conductance of synaptic channels were the same before and after kindling, implying that the channel number increased significantly. Immunocytochemical analysis of the inhibitory innervation showed that it was also unaltered by seizure induction. We also found that the effect of the positive modulator tetrahydrodeoxycorticosterone was reduced on the pyramidal neurones after kindling. In contrast, the potentiating effects of tetrahydrodeoxycorticosterone on non‐pyramidal cells were about the same after kindling as in control (sham) rats. These data indicate that amygdala kindling causes a shift in the inhibition ‘balance’ between the pyramidal and non‐pyramidal cells, perhaps leading to the disinhibition of pyramidal cells.
Hyperpolarization‐activated and cyclic nucleotide‐gated cation channel subunit 2 ion channels modulate synaptic transmission from nociceptive primary afferents containing substance P to secondary sensory neurons in laminae I–IIo of the rodent spinal dorsal horn
Authors: Papp Ildikó , Sz˝ucs Péter , Holló Krisztina , Erdélyi Ferenc , Szabó Gábor , Antal Miklós 
Published: September 2006

AbstractWe have previously demonstrated that hyperpolarization‐activated and cyclic nucleotide‐gated cation channel subunit 2 (HCN2) is expressed by terminals of peptidergic nociceptive primary afferents in laminae I–IIo of the rat spinal dorsal horn. In this study, we investigated the possible neurotransmitters and postsynaptic targets of these HCN2‐expressing primary afferent terminals in the superficial spinal dorsal horn by using immunocytochemical methods. We demonstrated that HCN2 widely colocalizes with substance P (SP), and that HCN2‐positive terminals that are also immunoreactive for SP form serial close appositions with dendrites and perikarya of neurokinin 1 receptor‐immunoreactive neurons. It was also found that HCN2‐immunoreactive terminals are frequently apposed to neurons that are immunoreactive for calbindin, µ‐opioid receptor and the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate receptor subunit GluR2, markers for excitatory interneurons. Investigating HCN2 immunoreactivity in glutamic acid decarboxylase 65‐green fluorescent protein transgenic mice, we found that HCN2‐positive terminals occasionally also contact cells that contain an isoform of glutamic acid decarboxylase (glutamic acid decarboxylase 65), a marker for GABAergic inhibitory neurons. Application of ZD7288, an antagonist of HCN channels, onto neurons that were recorded in spinal cord slices with whole‐cell patch‐clamp electrodes reduced the number of monosynaptic excitatory postsynaptic potentials evoked by electrical stimulation of primary afferents at nociceptive intensities. The results suggest that HCN2 may contribute to the modulation of membrane excitability of SP‐containing nociceptive primary afferent terminals, may increase the reliability of synaptic transmission from primary afferents to secondary sensory neurons and thus may play a role in the fine‐tuning of pain transmission from nociceptive primary afferents to neurons in the spinal dorsal horn.
Is the CCK2 receptor essential for normal regulation of body weight and adiposity?
Authors: Chen Hui , Kent Stephen , Morris Margaret J. 
Published: September 2006

AbstractCholecystokinin (CCK) is a gastrointestinal satiety signal released from the duodenum to terminate feeding, via CCK1 receptors. CCK2 receptors are considered to be involved in anxiety. CCK2 receptor knockout mice have increased body weight and food intake. Little is known regarding the effects of CCK2 receptor deficiency on adipose distribution and hypothalamic feeding regulators such as neuropeptide Y (NPY), a powerful stimulator of feeding. Adult (10 week) CCK2 receptor knockout and wild‐type mice were anaesthetized and killed by decapitation. Brain sections, organs and fat tissue were dissected. Plasma leptin, insulin and brain NPY content were measured by radioimmunoassay. Female CCK2 receptor knockout mice weighed more than control mice (22.0 ± 0.2 vs. 19.9 ± 0.4 g, P < 0.05), with this difference being less marked in male mice (26.4 ± 0.4 vs. 25.6 ± 0.6 g). Fat masses in all locations sampled were significantly smaller in CCK2 receptor knockout mice of both genders (P < 0.05), resulting in lower plasma leptin and insulin levels. NPY concentrations were significantly increased in arcuate nucleus and anterior hypothalamus in both male and female CCK2 receptor knockout mice, and total hypothalamic NPY content was increased by 7 and 9% in males and females, respectively (P < 0.05). CCK2 receptor deletion was associated with increased body weight and hypothalamic NPY content, but reduced fat masses and plasma leptin and insulin. Increased NPY might contribute to increased food intake in CCK2 receptor knockout mice. Further work needs to focus on the metabolic changes.
Concurrent visuomotor behaviour improves form discrimination in a patient with visual form agnosia
Authors: Schenk Thomas , Milner A. David 
Published: September 2006

AbstractIt is now well established that the visual brain is divided into two visual streams, the ventral and the dorsal stream. Milner and Goodale have suggested that the ventral stream is dedicated for processing vision for perception and the dorsal stream vision for action [A.D. Milner & M.A. Goodale (1995) The Visual Brain in Action, Oxford University Press, Oxford]. However, it is possible that ongoing processes in the visuomotor stream will nevertheless have an effect on perceptual processes. This possibility was examined in the present study. We have examined the visual form‐discrimination performance of the form‐agnosic patient D.F. with and without a concurrent visuomotor task, and found that her performance was significantly improved in the former condition. This suggests that the visuomotor behaviour provides cues that enhance her ability to recognize the form of the target object. In control experiments we have ruled out proprioceptive and efferent cues, and therefore propose that D.F. can, to a significant degree, access the object's visuomotor representation in the dorsal stream. Moreover, we show that the grasping‐induced perceptual improvement disappears if the target objects only differ with respect to their shape but not their width. This suggests that shape information per se is not used for this grasping task.