bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large‐scale analysis of the barley transcriptome based on expressed sequence tags
Authors: Zhang Hangning , Sreenivasulu Nese , Weschke Winfriede , Stein Nils , Rudd Stephen , Radchuk Volodymyr , Potokina Elena , Scholz Uwe , Schweizer Patrick , Zierold Uwe , Langridge Peter , Varshney Rajeev K. , Wobus Ulrich , Graner Andreas 
Published: September 2004

SummaryTo provide resources for barley genomics, 110 981 expressed sequence tags (ESTs) were generated from 22 cDNA libraries representing tissues at various developmental stages. This EST collection corresponds to approximately one‐third of the 380 000 publicly available barley ESTs. Clustering and assembly resulted in 14 151 tentative consensi (TCs) and 11 073 singletons, altogether representing 25 224 putatively unique sequences. Of these, 17.5% showed no significant similarity to other barley ESTs present in dbEST. More than 41% of all barley genes are supposed to belong to multigene families and approximately 4% of the barley genes undergo alternative splicing. Based on the functional annotation of the set of unique sequences, the functional category ‘Energy’ was further analysed to reveal tissue‐ and stage‐specific differences in gene expression. Hierarchical clustering of 362 differentially expressed TCs resulted in the identification of seven major clusters. The clusters reflect biochemical pathways predominantly activated in specific tissues and at various developmental stages. During seed germination glycolysis could be identified as the most predominant biochemical pathway. Germination‐specific glycolysis is characterized by the coordinated expression of phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase, whose antagonistic actions possibly regulate the flux of amino acids into protein biosynthesis and gluconeogenesis respectively. The expression of defence‐related and antioxidant genes during germination might be controlled by the ethylene‐signalling pathway as concluded from the coordinated expression of those genes and the transcription factors (TF) EIN3 and EREBPG. Moreover, because of their predominant expression in germinating seeds, TF of the AP2 and MYB type are presumably major regulators of germination.
Molecular cloning and characterization of norcoclaurine synthase, an enzyme catalyzing the first committed step in benzylisoquinoline alkaloid biosynthesis
Authors: Samanani Nailish , Liscombe David K. , Facchini Peter J. 
Published: September 2004

Summary(S)‐Norcoclaurine synthase (NCS) (EC 4.2.1.78) catalyzes the condensation of 3,4‐dihydroxyphenylethylamine (dopamine) and 4‐hydroxyphenylacetaldehyde (4‐HPAA) as the first committed step in the biosynthesis of benzylisoquinoline alkaloids such as morphine, sanguinarine, and berberine, in plants. A molecular clone encoding NCS was isolated from a meadow rue (Thalictrum flavum ssp. glaucum) cell suspension culture cDNA library. Heterologous expression of the NCS cDNA, truncated to remove a putative signal peptide, produced a recombinant protein with NCS activity. Recombinant NCS showed sigmoidal saturation kinetics for dopamine (Hill coefficient=1.98), hyperbolic saturation kinetics for 4‐HPAA (Km of 700 μm), and pH and temperature optima of 7.0 and 40°C, respectively, all similar to the purified, plant‐derived enzyme. NCS exhibits 28–38% identity, and putative structural homology, with the Bet v 1 allergen and pathogenesis‐related (PR)10 protein families. NCS also displays 35% identity with the enzyme (HYP1) responsible for hypericin biosynthesis in St John's wort (Hypericum perforatum). The novel catalytic functions of NCS and HYP1 define a new class of plant secondary metabolic enzymes within the Bet v 1 and PR10 protein families. Weaker homology was also detected between NCS and proteins identified in the latex of Papaver somniferum (opium poppy), and in Arabidopsis thaliana. A family of three to five NCS genes is abundantly expressed in the rhizome, followed by petioles and roots of T. flavum. NCS transcripts were localized to the immature endodermis and pericycle in roots, and the protoderm of leaf primordia in rhizomes; thus, the sites of NCS gene expression and berberine accumulation are temporally and spatially separated in roots and rhizomes respectively.
Effects of corn processing on the glycaemic and insulinaemic responses in horses
Authors: Vervuert I. , Coenen M. , Bothe C. 
Published: September 2004

SummaryThis study was conducted to evaluate the effects of different corn processing techniques on the glycaemic and insulinaemic responses in horses. It was hypothesized that the changes in pre‐caecal starch digestibility caused by various types of corn processing would alter the post‐prandial glycaemic and/or insulinaemic response. Six horses were fed in random order: untreated, finely ground, steamed, micronized, steam‐flaked and popped corn. The total corn intake was adjusted to 630 g starch/horse/day (1.2–1.5 g starch/kg BW/day). During a stabilization period of 10 days, horses also received 6 kg grass hay/horse/day. At blood collection day horses were fed their test diet (exclusively corn), and blood samples were taken at defined times. Corn feeding resulted in a significant increase in mean plasma glucose and insulin concentration, but glucose and insulin peaks as well as areas under the curve (AUC) were not clearly influenced by corn processing. The glycaemic index (in which each test diet's plasma glucose AUC was expressed relative to untreated corn) varied between 91.4 ± 9.4% (steamed corn) and 108.4 ± 11.8% (popped corn, treatment n.s.), the insulinaemic index (in which each test diet's plasma insulin AUC was expressed relative to untreated corn) ranged between 98.2 ± 12.6% (steamed corn) and 121.0 ± 29.9% (micronized corn, treatment n.s.). However, the well‐established improvement in pre‐caecal starch digestibility was not reflected by differences in the glucose or insulin responses.
Effect of size on electrolyte apparent absorption rates and fermentative activity in dogs
Authors: Weber M. P. , Hernot D. , Nguyen P. G. , Biourge V. C. , Dumon H. J. 
Published: September 2004

SummaryThe objectives of the study were to assess overall electrolyte absorption capacity as well as fermentative activity in dogs varying in body size in order to verify whether these parameters can explain the poor faecal quality in large dogs. Four breeds of dogs were used: six Miniature Poodles (MP), six Standard Schnauzers (SS), six Giant Schnauzers (GS) and six Great Danes (GD). Net absorption rates of electrolytes were assessed by calculating the apparent digestibility of sodium and potassium and measuring their content in stool. Fermentative activity was calculated by measuring faecal concentrations of lactic acid and short‐chain fatty acids. The results showed higher faecal concentrations of fermentation products and electrolytes as well as poorer digestibility of electrolytes in Giant Schnauzers and Great Danes. Strong positive correlations were found between these different parameters and stool quality (scores and moisture). Lower overall electrolyte absorption and higher fermentative activity could thus be factors capable of explaining poorer faecal quality in these two large dog breeds.
Modulation of premotor mirror neuron activity during observation of unpredictable grasping movements
Authors: Gangitano Massimo , Mottaghy Felix M. , Pascual‐Leone Alvaro 
Published: September 2004

AbstractUsing transcranial magnetic stimulation, we explored the properties of premotor mirror neurons during the passive observation of a reaching–grasping movement in human subjects. Two different experiments were run using video‐clips as visual stimuli. Video‐clips showed a normally performed (control stimulus) or an anomalous reaching–grasping movement executed by delaying the time of the appearance of the maximal finger aperture (experiment 1), or substituting it with an unpredictable closure (experiment 2). Motor evoked potentials were recorded at different time‐points during the observation of the video‐clips. Profiles of cortical excitability were drawn and compared with the kinematic profiles of the corresponding movement. Passive observation of the natural movement evoked a profile of cortical excitability that is in concordance with the timing of the kinematic profile of the shown finger movements. Observation of the uncommon movements did not exert any modulation (experiment 1) or evoked an activity that matched, at the beginning, the modulation obtained with observation of the natural movement (experiment 2). Results show that the resonant motor plan is loaded as whole at the beginning of observation and once started tends to proceed to its completion regardless of changes to the visual cues. The results exclude the possibility of a temporal fragmentation of the resonant plan, because activation of different populations of mirror neurons for each phase of the ongoing action. They further support the notion of the role of the mirror system as neural substrate for the observing–execution matching system and extend the current knowledge regarding mechanisms that trigger the internal representation of an action.
Reduction in endogenous parkin levels renders glial cells sensitive to both caspase‐dependent and caspase‐independent cell death
Authors: MacCormac Luci P. , Muqit Miratul M. K. , Faulkes David J. , Wood Nicholas W. , Latchman David S. 
Published: September 2004

AbstractMutations in the parkin gene give rise to a familial form of Parkinson's disease, autosomal recessive juvenile Parkinsonism (AR‐JP). Although the exact mechanisms are unclear, it is thought that these ‘loss‐of‐function’ mutations contribute to the pathological process by interfering with parkin's E3 ubiquitin ligase activity. In order to mimic the in vivo loss‐of‐function, we produced tet‐inducible glial cell lines that, in the presence of doxycycline, were able either to under‐ or to over‐express the parkin protein. Using this cell‐culture system, we found that the induced alteration of parkin levels in glial cell lines caused different responses compared with their un‐induced counterparts under conditions of stress (staurosporine, hydrogen peroxide and dopamine). In particular, reduction in the levels of parkin within the transfected cells rendered them more susceptible to both apoptotic and necrotic cell death. Interestingly, blocking the cell death pathway with caspase inhibitors rescued the cells under‐expressing parkin from only some of the stress‐induced death. These findings implicate a pathogenic role of glial cells in the pathogenesis of AR‐JP caused by mutations in the parkin gene.
The contribution of activated phagocytes and myelin degeneration to axonal retraction/dieback following spinal cord injury
Authors: McPhail Lowell T. , Stirling David P. , Tetzlaff Wolfram , Kwiecien Jacek M. , Ramer Matt S. 
Published: September 2004

AbstractMyelin‐derived molecules inhibit axonal regeneration in the CNS. The Long–Evans Shaker rat is a naturally occurring dysmyelinated mutant, which although able to express the components of myelin lacks functional myelin in adulthood. Given that myelin breakdown exposes axons to molecules that are inhibitory to regeneration, we sought to determine whether injured dorsal column axons in a Shaker rat would exhibit a regenerative response absent in normally myelinated Long–Evans (control) rats. Although Shaker rat axons did not regenerate beyond the lesion, they remained at the caudal end of the crush site. Control rat axons, in contrast, retracted and died back from the edge of the crush. The absence of retraction/dieback in Shaker rats was associated with a reduced phagocytic reaction to dorsal column crush around the caudal edge of the lesion. Systemic injection of minocycline, a tetracycline derivative, in control rats reduced both the macrophage response and axonal retraction/dieback following dorsal column injury. In contrast, increasing macrophage activation by spinal injection of the yeast particulate zymosan had no effect on axonal retraction/dieback in Shaker rats. Schwann cell invasion was reduced in minocycline‐treated control rats compared with untreated control rats, and was almost undetectable in Shaker rats, suggesting that like axonal retraction/dieback, spinal Schwann cell infiltration is dependent upon macrophage‐mediated myelin degeneration. These results indicate that following spinal cord injury the phagocyte‐mediated degeneration of myelin and subsequent exposure of inhibitory molecules to the injured axons contributes to their retraction/dieback.
GABAA receptors signal bidirectional reward transmission from the ventral tegmental area to the tegmental pedunculopontine nucleus as a function of opiate state
Authors: Laviolette Steven R. , Van Der Kooy Derek 
Published: September 2004

AbstractThe brainstem tegmental pedunculopontine nucleus (TPP) is involved in reward signalling and is functionally and anatomically linked to the VTA. We examined the possible role of the TPP as a reward transmission output for GABAA receptors in the VTA in rats not previously exposed to opiates vs. rats that were chronically exposed to and in withdrawal from opiates or in rats that had recovered from chronic opiate exposure. Bilateral lesions of the TPP blocked the rewarding effects of a GABAA antagonist but not the rewarding effects of a GABAA receptor agonist in rats previously unexposed to opiates. This functional pattern was reversed in rats that were dependent on opiates and in withdrawal. However, once rats had recovered from chronic opiate exposure the functional parameters of VTA GABAA receptor reward signalling reverted to the pattern observed in animals that had not been exposed to opiates. These findings suggest that GABAA receptors in the VTA can regulate differential reward signalling through separate neural systems during the transition from a drug‐naive to a drug‐dependent and withdrawn state.
Recovery of bimodal locomotion in the spinal‐transected salamander, Pleurodeles waltlii
Authors: Chevallier Stéphanie , Landry Marc , Nagy Frédéric , Cabelguen Jean‐Marie 
Published: September 2004

AbstractElectromyographic (EMG) analysis was used to provide an assessment of the recovery of locomotion in spinal‐transected adult salamanders (Pleurodeles waltlii). EMG recordings were performed during swimming and overground stepping in the same animal before and at various times (up to 500 days) after a mid‐trunk spinalization. Two–three weeks after spinalization, locomotor EMG activity was limited to the forelimbs and the body rostral to the transection. Thereafter, there was a return of the locomotor EMG activity at progressively more caudal levels below the transection. The animals reached stable locomotor patterns 3–4 months post‐transection. Several locomotor parameters (cycle duration, burst duration, burst proportion, intersegmental phase lag, interlimb coupling) measured at various recovery times after spinalization were compared with those in intact animals. These comparisons revealed transient and long‐term alterations in the locomotor parameters both above and below the transection site. These alterations were much more pronounced for swimming than for stepping and revealed differences in adaptive plasticity between the two locomotor networks. Recovered locomotor activity was immediately abolished by retransection at the site of the original spinalization, suggesting that the spinal cord caudal to the transection was reinnervated by descending brain and/or propriospinal axons, and that this regeneration contributed to the restoration of locomotor activity. Anatomical studies conducted in parallel further demonstrated that some of the regenerated axons came from glutamatergic and serotoninergic immunoreactive cells within the reticular formation.
Critical role of the C‐terminal segment in the maturation and export to the cell surface of the homopentameric α7–5HT3A receptor
Authors: Pons S. , Sallette J. , Bourgeois J. P. , Taly A. , Changeux J. P. , Devillers‐Thiéry A. 
Published: September 2004

AbstractMany neurological pathologies are related to misfolded proteins. During folding and assembly in the endoplasmic reticulum, the nicotinic acetylcholine receptor (nAChR) subunits undergo several conformational changes to acquire the ability to bind ligands. After folding and maturation, by mechanisms largely unknown, receptors are exported to the cell surface. We investigated the maturational role of the extracellular C‐terminal segment located at the boundary between the extracellular and the transmembrane domains. In the functional chimeric α7–5HT3A receptor used as a model system, amino acids from the C‐terminal segment were successively deleted or mutated. Upon progressive shortening of the peptide we observed less and less α‐bungarotoxin binding sites until no sites could be detected when the entire peptide had been deleted (chimera Del 5). Protein synthesis and pentameric assembly were not altered. In Del 5 transfected cells, pentameric receptors present in the endoplasmic reticulum were not detected on the cell surface where Del 5 proteins appeared as patches. With the Del 5 chimera, export of proteins to the cell surface diminished to about half that of wild‐type. We propose that the C‐terminal segment plays a double role: (i) through an interaction between the penultimate tyrosine residue of the C‐terminal segment and the Cys loop of the N‐terminal domain, it locks the receptor in a mature α‐bungarotoxin binding conformation; (ii) this mature conformation, in turn, masks a retention signal present in the first transmembrane segment allowing properly assembled and matured receptors to escape to the cell surface.
The role of the magnocellular pathway in serial deployment of visual attention
Authors: Cheng Alicia , Eysel Ulf T. , Vidyasagar Trichur R. 
Published: September 2004

AbstractNormal human visual function often demands detection of a target among a number of other objects cluttering the scene, such as when searching for a known face in a crowd. In these and similar tasks, the search performed is a serial one, with an attentional spotlight scanning the objects of the scene. We have investigated whether one of the afferent channels in vision, the colour‐blind magnocellular pathway, is essential in such serial searches. We did this by using items that were isoluminant with the background but of a different colour, for which the magnocellular cells would be blind. The search in these conditions required much longer reaction times than when even a very small luminance contrast (2%) was added to the items. Because such luminance contrasts can be detected only by magnocellular cells and not by neurons of the other channels (parvocellular and koniocellular), the magnocellular pathway appears vitally important for serial search. In contrast, in a feature search task, which does not require allocation of attentional resources, the search was as efficient with isoluminance as when luminance contrast was added to the items.
Axon‐dominant localization of cell‐surface cholesterol in cultured hippocampal neurons and its disappearance in Niemann–Pick type C model cells
Authors: Tashiro Yuichi , Yamazaki Tsuneo , Shimada Yukiko , Ohno‐Iwashita Yoshiko , Okamoto Koichi 
Published: September 2004

AbstractThere is growing evidence showing the important role of cholesterol in maintaining neuronal function. In particular, much attention has been paid to the role of the cholesterol‐rich microdomains called lipid rafts. However, the cholesterol distribution on neurons is not clear. Here, we investigated localization of cholesterol in cultured rat hippocampal neurons, using filipin and a novel cholesterol‐binding reagent BCθ. In our culture system, BCθ detects only cell‐surface cholesterol, whereas filipin stains both intracellular and cell‐surface cholesterol. BCθ staining appeared visible in a maturation‐dependent manner and showed axon‐dominant distribution of cell‐surface cholesterol in fully matured neurons. A part of this cholesterol on axons was resistant to detergents at 4 °C, and thus might be involved in lipid rafts. Interestingly, Niemann–Pick type C model neurons induced by class 2 amphiphiles lost the cell‐surface but not the intracellular cholesterol staining. Niemann–Pick type C disease is caused by the disruption of intracellular cholesterol transport and is known to induce neurodegeneration in brains accompanied by formation of neurofibrillary tangles. Our observations suggest the important role of cell‐surface cholesterol in maintaining a functional axonal membrane and indicate that the observed defect in axonal surface cholesterol might lead to neurodegeneration.
Adenosine A2A receptors are involved in physical dependence and place conditioning induced by THC
Authors: Soria Guadalupe , Castañé Anna , Berrendero Fernando , Ledent Catherine , Parmentier Marc , Maldonado Rafael , Valverde Olga 
Published: September 2004

AbstractA2A adenosine and CB1 cannabinoid receptors are highly expressed in the central nervous system, where they modulate numerous physiological processes including adaptive responses to drugs of abuse. Both purinergic and cannabinoid systems interact with dopamine neurotransmission (through A2A and CB1 receptors, respectively). Changes in dopamine neurotransmission play an important role in addictive‐related behaviours. In this study, we investigated the contribution of A2A adenosine receptors in several behavioural responses of Δ9‐tetrahydrocannabinol (THC) related to its addictive properties, including tolerance, physical dependence and motivational effects. For this purpose, we first investigated acute THC responses in mice lacking A2A adenosine receptors. Antinociception, hypolocomotion and hypothermia induced by acute THC administration remained unaffected in mutant mice. Chronic THC treatment developed similar tolerance to these acute effects in wild‐type and A2A‐knockout mice. However, differences in the body weight pattern were found between genotypes during such chronic treatment. Interestingly, the somatic manifestations of SR141716A‐precipitated THC withdrawal were significantly attenuated in mutant mice. The motivational responses of THC were also evaluated by using the place‐conditioning paradigm. A significant reduction of THC‐induced rewarding and aversive effects was found in mice lacking A2A adenosine receptors in comparison with wild‐type littermates. Binding studies revealed that these behavioural changes were not associated with any modification in the distribution and/or functional activity of CB1 receptors in knockout mice. Therefore, this study shows, for the first time, a specific involvement of A2A receptors in the addictive‐related properties of cannabinoids.