bluuebunny/crossref_metadata_2025 huggingface dataset:
Water stress and Sphaeropsissapinea as a latent pathogen of red pine seedlings
Authors: Stanosz G. R. , Blodgett J. T. , Smith D. R. , Kruger E. L.
Published: March 2003

•  The role of water stress in the initiation of collar rot by Sphaeropsis sapinea in asymptomatically colonized Pinus resinosa seedlings is reported.

• Mortality and frequency of identification of the pathogen was quantified for seedlings subjected to different water regimes or watering regime–fungicide (benomyl) combinations in glasshouse experiments.

•  In experiment 1, seedling mortality ranged from 8% of repeatedly watered seedlings to 50% of those in the driest regime; data analysis indicated a high probability that mortality was not independent of watering regime. Seedlings developed symptoms resembling those of Sphaeropsis collar rot, and S. sapinea was identified from living (42%) and dead (92%) seedlings. In experiment 2, mortality of repeatedly watered seedlings was low, irrespective of fungicide application. For nonwatered seedlings, however, mortality was greater among seedlings not treated with fungicide (61%) than among benomyl‐treated seedlings (37%); data analysis indicated a high probability that mortality was not independent of fungicide treatment.

• Sphaeropsis sapinea can act as a latent pathogen; physiological alteration, through water stress, can effect release from the quiescent condition to result in rapid disease development.
Free‐air CO2 enrichment (FACE) using pure CO2 injection: system description
Authors: Okada M. , Lieffering M. , Nakamura H. , Yoshimoto M. , Kim H. Y. , Kobayashi K.
Published: March 2003

A free air CO2 enrichment (FACE) system in which rice was grown under elevated CO2 conditions by releasing high pressure, pure CO2 from emission tubes surrounding the crop is described here. Unlike other (FACE) systems, blowers were not used to mix the emitted CO2 with the surrounding air.

 Four 12‐m diameter emission structures (‘rings’) were constructed. Monitoring and control of CO2 emission was carried out by a series of CO2 and wind sensors, data loggers, controllers and valves. The target CO2 concentration ([CO2]) was 200 µmol mol−1 above ambient; enrichment was carried out continuously.

 Temporal [CO2] control was adequate, with c. 60 and 90% of the air samples at ring center having a [CO2] within 10 and 20% of the target, respectively. Spatial [CO2] distribution was also adequate, with 60% of the ring area having a [CO2] that was within 15% of that at the center.

 At comparable wind speeds, the pure CO2 injection FACE system described here had a similar performance to that of FACE designs that use blowers to mix the injected CO2 with the air.
The costs of reproduction in plants
Authors: Obeso José Ramón
Published: March 2003

This review reports on the processes associated with costs of reproduction, including some theoretical considerations, definitions and methodological aspects, followed by a list of the situations where costs are difficult to find. Despite some exceptions, case studies, examined by trade‐offs between reproduction and other life‐history traits, generally support the predictions of the cost of reproduction hypothesis. The cost of reproduction as an evolutionary determinant of sexual dimorphism in life history traits in dioecious species was specifically tested, considering that the higher cost of reproduction in females has driven the life history traits related to sexual dimorphism. Females of woody dioecious species were consistently smaller than males supporting the costs of reproduction hypothesis. By contrast, females of herbaceous perennials were generally the larger sex, which did not fit the expectations of the hypothesis. Finally, the mechanisms that enable the compensation of the reproductive costs are detailed, including the plastic responses of photosynthesis and growth, the effects of the timing of investment, plant architecture and plant physiological integration.

Contents

Summary
321

I.
Introduction
321

II.
Theory on costs of reproduction
322

III.
Methodological aspects
324

IV.
Empirical evidence
328

V.
Plant size and costs of reproduction
330

VI.
Costs of reproduction in sexually dimorphic plants
331

VII.
Compensation of the costs
333

VIII.
Concluding comments and future perspectives
336

Acknowledgements
337

References
337
The profile of women entrepreneurs: a sample from Turkey
Authors: Ufuk Hatun , Özgen Özlen
Published: March 2003

This research was carried out among 220 married women in business in Ankara. Its aim was to determine the profile of women entrepreneurs. A random sampling method was used and data were collected through individual interviews (face‐to‐face). The study examined working status, reasons for being in business and the types of businesses involved. It examined the difficulties experienced in starting up and maintaining the businesses, the risks involved, earnings, the characteristics of the entrepreneurs and future planning. Government rules and regulations were considered, as was the willingness of women entrepreneurs to participate in training programmes. The women’s ages, educational levels and the extent of their business experience were also examined.
An analysis of modern fashion designs as influenced by Asian ethnic dress
Authors: Yu Haekyung L. , Kim Chanju , Lee Juhyeon , Hong Nayoung
Published: March 2003

This study analysed modern fashion designs which show influences of Asian ethnic dresses focusing on China, Indonesia, Japan, Korea and Vietnam. A total of 190 designs presented during 1982–97 were collected from seven magazines. There were 68 designs with Chinese influences, 49 for Japan, 35 for Korea, 21 for Indonesia and 5 for Vietnam. Twelve designs showed the influences of more than one country. Each design was content analysed in terms of eleven aspects (shape, garment type, silhouette, colour, feature of fabric, surface pattern, trimming, how to wear, accessories, hair‐style and make‐up). The degree of influence was measured on a 3‐point scale ranging from 1 (symbolic resemblance) to 2 (modification) and 3 (replication). The results confirmed that China and Japan have been the most well‐known sources of Oriental culture in fashion world. Influence of ethnic dresses were most evident in the aspects related to materials (surface pattern, feature of fabric and colour). The Indonesian sarong and the way to wrap skirts around the waist were also frequently adopted in modern fashion.
Determinants of consumers’ aesthetic responses to Point‐of‐Purchase materials
Authors: Jansson C. , Bointon B. , Marlow N.
Published: March 2003

The four‐dimensional nature of the Kaplans’ model of aesthetic response to images was tested on Point‐of‐Purchase (POP) material. It was found that only two robust dimensions emerged in the analysis, Clarity and Mystery. These however, had a significant influence on the subjects’ rating of the POP’s attractiveness. Path analysis suggested each of these dimensions was independent of the other. The implications of the findings are discussed and possible future areas of research identified.
An approach to the detection of synthetic milk in dairy milk: 4. Effect of the addition of synthetic milk on the flow behaviour of pure cow milk
Authors: Paradkar Manish M , Singhal Rekha S , Kulkarni Pushpa R
Published: March 2003

The flow behaviour of cow milk, synthetic milk and their blends was evaluated with a Haake rheometer. Changes in flow behaviour are thought to be due to detergent, an important constituent of synthetic milk, which emulsifies the vegetable fat in the aqueous phase. The results are of value in detecting very low levels (1–10%) of synthetic milk in cow milk.
Fatty acid composition of raw caprine milk of a native Greek breed during lactation
Authors: Kondyli Efthymia , Katsiari Maria C
Published: March 2003

The fatty acid (FA) and free fatty acid (FFA) profiles of caprine milk from a native Greek breed were investigated during a period of 6 months (January–June). The most abundant FAs were palmitic, oleic, stearic and capric. The short‐ and medium‐chain FAs represented 17.5 and 14.5% of total FA, respectively, while long‐chain FAs accounted for the rest (68.0%). From January to April, the major FFAs were acetic, palmitic, stearic and caproic, but afterwards, acetic and propionic were the principal FFAs, followed by stearic, palmitic, oleic and capric.
Cloning and Expression of a G Protein‐Linked Acetylcholine Receptor from Caenorhabditis elegans
Authors: Lee Yong‐Seok , Park Yang‐Seo , Chang Deok‐Jin , Hwang Jung Me , Min Churl Ki , Kaang Bong‐Kiun , Cho Nam Jeong
Published: March 2003

Abstract : We have isolated a cDNA clone from the nematode
Caenorhabditis elegans that encodes a protein of greatest sequence
similarity to muscarinic acetylcholine receptors. This gene codes for a
polypeptide of 682 amino acids containing seven putative transmembrane
domains. The amino acid identities, excluding a highly variable middle portion
of the third intracellular loop, to the human m1‐m5 receptors are 28‐34%. When
this cloned receptor was coexpressed with a G protein‐gated inwardly
rectifying K+ channel (GIRK1) in Xenopus oocyte, acetylcholine was able to elicit the GIRK current. This acetylcholine‐induced current was substantially inhibited by the muscarinic antagonist atropine in a reversible manner. However, another muscarinic agonist oxotremorine and antagonists scopolamine and pirenzepine had little or negligible effects on this receptor. Taken together, these results suggest that the cloned gene encodes a G protein‐linked acetylcholine receptor that is most similar to but pharmacologically distinct from muscarinic acetylcholine receptors.
Different Neuroligands and Signal Transduction Pathways Stimulate CREB Phosphorylation at Specific Developmental Stages Along Oligodendrocyte Differentiation
Authors: Sato‐Bigbee Carmen , Pal Shubhro , Chu Annie K.
Published: March 2003

Abstract : We have shown previously that the pattern of expression
of the transcription factor CREB (cyclic AMP‐response element binding protein)
in developing oligodendrocytes (OLGs) suggests a role during a period that
precedes the peak of myelination in rat brain. We have now investigated the
signaling pathways that could be responsible for activating CREB by
phosphorylation at different stages along OLG maturation. CREB phosphorylation
was studied in short‐term cultures of immature OLG precursor cells and young
OLGs isolated from 4‐ and 11‐day‐old rat cerebrum, respectively. The results
indicated that at both developmental stages, CREB phosphorylation could be
stimulated by either increased concentrations of cyclic AMP and cyclic
AMP‐dependent protein kinase activation or increased Ca2+ levels
and a protein kinase C activity. The results also showed that CREB
phosphorylation in immature OLG precursor cells could be up‐regulated by
treatment with histamine, carbachol, glutamate, and ATP (neuroligands known to
increase Ca2+ levels in these cells), by signaling cascade(s) that involve a protein kinase C activity, as well as the mitogen‐activated protein kinase pathway. In contrast, in cells isolated from 11‐day‐old rats, at a developmental stage that immediately precedes the beginning of the active period of myelin synthesis, CREB phosphorylation was only stimulated by treatment with the β‐adrenergic agonist isoproterenol in a process that appears to be mediated by a cyclic AMP/cyclic AMP‐dependent protein kinase‐dependent pathway. These results support the idea that CREB could be a mediator of neuronal signals that, coupled to specific signal transduction cascades, may play different regulatory roles at specific stages along OLG differentiation.
Evidence for the Sequential Formation of Two Complexes Between an Uptake Inhibitor, GBR 12783 [1‐[2‐(Diphenylmethoxy)ethyl]‐4‐(3‐Phenyl‐2‐Propenyl)piperazine], and the Neuronal Transporter of Dopamine
Authors: Do‐Régo Jean‐Claude , Hue Hervé , Costentin Jean , Bonnet Jean‐Jacques
Published: March 2003

Abstract : Incubation of a crude synaptosomal fraction from rat
striatum with GBR 12783 at 37°C produced an inhibition of the specific
uptake of [3H]dopamine that increased with time. The inhibition
increased when GBR 12783 was present during preincubation and incubation
(IC50 = 1.85 ± 0.1 nM) instead of incubation alone
(IC50 = 25 ± 3.5 nM). Time‐course studies of uptake
inhibition demonstrated that a first collision transporter‐inhibitor complex
(TI) was formed immediately after addition of GBR 12783 so that the initial
uptake velocity (Vo) decreased for increasing
concentrations of inhibitor (Ki≥ 20 nM). TI
slowly isomerized to a more stable complex TI*
(K*i≤ 5 nM) with a value of
t1/2 = 20‐270 s. Fits of data to model 2 in which the
steady‐state uptake (VS) is set to zero were generally
preferred, suggesting that formation of TI* could tend to
irreversibility, as a consequence of a very low reverse isomerization. As
expected, k, Vo, and VS tended to
steady‐state values in an asymptotic manner for high concentrations of GBR
12783. GBR 12783 at 2.5 nM produced a mixed inhibition of the uptake,
with an increase in KM and a decrease in
Vmax ; these effects were improved for 10 nM GBR
12783 and at 20°C. These results are discussed in relation to previous
data concerning [3H]GBR 12783 binding. The present work gives the first experimental demonstration that dopamine uptake blockers can act according to a two‐step mechanism of inhibition ; this is of great interest, because these inhibitors can oppose the effects of cocaine or amphetamine on the transporter according to a reaction that is partly nondependent on the concentration of the abused agent.
Expression of c‐fos, c‐jun, and N‐terminal kinase (JNK) in a Development Model of Induced Apoptotic Death in Neurons of the Substantia Nigra
Authors: Oo Tinmarla , Henchcliffe Claire , James Daylon , Burke Robert E.
Published: March 2003

Abstract : The transcription factors c‐fos and c‐jun have been proposed to play a role in the initiation of programmed cell death in neurons. We have shown that programmed cell death, with the morphology of apoptosis, occurs in dopamine neurons of the substantia nigra (SN) during normal postnatal development and that this death event can be induced by early striatal target injury. We have investigated the relationship between c‐fos and c‐jun protein expression and induced death in neurons of the SN. Although c‐fos is induced, it is unlikely to play a role in cell death, because its expression is not well correlated with apoptotic death either temporally or at a cellular level. Expression of c‐jun, however, is both temporally and regionally correlated with induction of death, and, at a cellular level, it colocalizes with apoptotic morphology. The increased expression of c‐jun is likely to be functionally significant, because it is associated with increased c‐jun expression. JNK expression also colocalizes with apoptotic morphology. We conclude that c‐jun is likely to play a role in the initiation of apoptotic cell death in these neurons.
Ribosomal RNAs Synthesized by Isolated Squid Nerves and Ganglia Differ from Native Ribosomal RNAs
Authors: Perrone‐Capano Carla , Perrone‐Capano Carla , Crispino Marianna , Menichini Enrico , Kaplan Barry B. , Giuditta Antonio
Published: March 2003

Abstract : The large rRNA of the squid comprises two chains that may
be dissociated by heating at 65°C. A single chain constitutes the small
rRNA. Surprisingly, the RNAs synthesized by dissected squid fin nerves and
stellate nerves and ganglia differed in size from native rRNAs and did not
manifest thermal instability. Nonetheless, they resembled native rRNAs in
relative abundance, subcellular distribution, lack of poly(A), and metabolic
stability. In addition, newly synthesized RNA was localized in nerve and glial
cells, as shown by autoradiographic analysis, and was assembled into 80S
ribosomes, which supported the synthesis of neuron‐specific neurofilament
proteins. Following incubation of nerves and ganglia for >10 h, native
rRNAs started to disappear, while two major newly synthesized RNAs
progressively accumulated. As a result, after 20 h, native rRNAs were
substituted by the two novel RNAs. With use of 32P‐cDNA synthesized from the latter RNAs as a probe, the novel RNAs demonstrated a considerable degree of homology with native rRNA in northern analysis. Taken together, the data suggest that in dissected squid nerves and ganglia, the synthesis of native rRNAs is gradually terminated while two novel rRNAs are being synthesized, presumably as a correlate of reactive gliosis and/or neuronal degeneration/regeneration.
Suppression of Heme Oxygenase‐1 mRNA Expression by Interferon‐γ in Human Glioblastoma Cells
Authors: Takahashi Kazuhiro , Nakayama Masaharu , Takeda Kazuhisa , Fujita Hiroyoshi , Shibahara Shigeki
Published: March 2003

Abstract: Heme oxygenase is a rate‐limiting enzyme in heme catabolism that cleaves heme to form biliverdin, carbon monoxide, and iron. Heme oxygenase‐1 is an inducible isozyme and is expressed in many types of cells and tissues. Large amounts of these heme degradation products may be noxious to the host, especially in the brain. We therefore searched for the factors that suppress the expression of heme oxygenase‐1. Northern blot analysis showed that treatment with interferon‐γ and with interleukin‐1β for 24 h decreased the expression levels of heme oxygenase‐1 mRNA to ∼20 and ∼50% of the control levels, respectively, in a human glioblastoma cell line, T98G. Treatment with a combination of these two cytokines additively decreased the expression levels of heme oxygenase‐1 mRNA. Western blot analysis showed that the expression level of heme oxygenase‐1 protein was also decreased by treatment with interferon‐γ, but not with interleukin‐1β. Moreover, pretreatment with interferon‐γ partially suppressed the induction of heme oxygenase‐1 mRNA expression caused by either sodium nitroprusside, cadmium, or hemin. These findings raise the possibility that the expression of heme oxygenase‐1 is down‐regulated by interferon‐γ in the nervous system.
Glial Cells Mediate Toxicity in Glutathione‐Depleted Mesencephalic Cultures
Authors: Mytilineou Catherine , Leonardi Efthimia T. Kokotos , Kramer Brian C. , Jamindar Tejal , Olanow C. Warren
Published: March 2003

Abstract: We have examined the role of glial cells in the toxicity that results from inhibition of reduced glutathione (GSH) synthesis by L‐buthionine sulfoximine (BSO) in mesencephalic cell cultures. We show that GSH depletion, to levels that cause total cell loss in cultures containing neurons and glial cells, has no effect on cell viability in enriched neuronal cultures. An increase in the plating cell density sensitizes glia‐containing cultures to GSH depletion‐induced toxicity. This suggests that cell death in this model is the consequence of events that are induced by GSH depletion and are mediated by glial cells. The antioxidant ascorbic acid and the lipoxygenase (LOX) inhibitor nordihydroguaiaretic acid (1‐10 μM) provide full protection from BSO toxicity, indicating that arachidonic acid metabolism through the LOX pathway and the generation of reactive oxygen species play a role in the loss of cell viability. In contrast, inhibition of nitric oxide (NO) synthase affords only partial protection from BSO toxicity, suggesting that increased NO production cannot entirely account for cell death in this model. Our data provide evidence that GSH depletion in the presence of glial cells leads to neuronal degeneration that can be prevented by inhibition of LOX. This may have relevance to the pathogenesis of Parkinson’s disease, where glial activation and depletion of GSH have been found in the substantia nigra pars compacta.
Systemic Administration of NMDA and AMPA Receptor Antagonists Reverses the Neurochemical Changes Induced by Nigrostriatal Denervation in Basal Ganglia
Authors: Vila Miquel , Marin Concepció , Ruberg Merle , Jimenez Anna , Raisman‐Vozari Rita , Agid Yves , Tolosa Eduardo , Hirsch Etienne C.
Published: March 2003

Abstract: In Parkinson’s disease, nigrostriatal denervation leads to an overactivity of the subthalamic nucleus and its target areas, which is responsible of the clinical manifestations of the disease. Because the subthalamic nucleus uses glutamate as neurotransmitter and is innervated by glutamatergic fibers, pharmacological blockade of glutamate transmission might be expected to restore the cascade of neurochemical changes induced by a dopaminergic denervation within the basal ganglia. To test this hypothesis, two types of glutamate antagonists, the NMDA receptor antagonist MK‐801 and the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor antagonist LY293558, were administered systemically, either alone or in combination with L‐DOPA, in rats with a unilateral 6‐hydroxydopamine lesion of the nigrostriatal dopamine pathway. The effect of treatment was assessed neurochemically by analyzing at the cellular level the functional activity of basal ganglia output structures and the subthalamic nucleus using the expression levels of the mRNAs coding for glutamic acid decarboxylase and cytochrome oxidase, respectively, as molecular markers of neuronal activity. The present study shows that treatment with glutamate antagonists, and particularly with AMPA antagonists, alone or in combination with L‐DOPA, reverses the overactivity of the subthalamic nucleus and its target areas induced by nigrostriatal denervation. These results furnish the neurochemical basis for the potential use of glutamate antagonists as therapeutic agents in Parkinson’s disease.
Adaptive Changes in Postsynaptic Dopamine Receptors Despite Unaltered Dopamine Dynamics in Mice Lacking Monoamine Oxidase B
Authors: Chen Lian , He Ming , Sibille Etienne , Thompson Alexis , Sarnyai Zoltan , Baker Harriet , Shippenberg Toni , Toth Miklos
Published: March 2003

Abstract : Monoamine oxidase (MAO) B is considered a key enzyme in dopamine metabolism. The present studies, conducted in MAO B knockout mice, show that lack of MAO B does not alter extracellular levels of dopamine in striatum. Similarly, the synthesis, storage, uptake, and release of dopamine are also unaltered. However, autoradiography revealed a significant up‐regulation of the D2‐like dopamine receptors in the striatum of MAO B knockout mice. Mutant mice also exhibit a functional supersensitivity of D1‐dopamine receptors in the nucleus accumbens. Thus, the agonist SKF 38,393‐induced c‐Fos immunoreactivity was significantly increased in knockout mice as compared with wild‐type controls. In view of the apparently normal basal dopamine dynamics observed in MAO B knockout mice, we hypothesize that a dopamine‐independent mechanism underlies adaptations in dopamine receptor function that occur as a consequence of MAO B depletion. Finally, these findings suggest that chronic administration of MAO inhibitors, as occurs in the treatment of Parkinson's disease and depression, may be associated with an increased responsiveness of CNS neurons to dopamine receptor ligands.
Hypoxia Induces Selective SAPK/JNK‐2‐AP‐1 Pathway Activation in the Nucleus Tractus Solitarii of the Conscious Rat
Authors: Gozal Evelyne , Simakajornboon Narong , Dausman Jason D. , Dan Xue Ying , Corti Miriam , El‐Dahr Samir S. , Gozal David
Published: March 2003

Abstract : In the nucleus tractus solitarii, NMDA glutamate

receptors are critical to the hypoxic ventilatory response. However, the

signal transduction pathways underlying the hypoxic ventilatory response

remain undefined. To assess the effect of a moderate hypoxic stimulus (10%

O2) on tyrosine phosphorylation of proteins in the nucleus tractus solitarii, tissue lysates were harvested by repeated punch sampling at 0, 1, 10, and 60 min of hypoxia and examined for the presence of phosphorylated tyrosine residues by immunoblotting. Time‐dependent phosphotyrosine increases occurred in proteins migrating at regions corresponding to molecular masses of 38‐42, 50, 55, and 60 kDa, which were attenuated by pretreatment with the NMDA receptor channel blocker, MK‐801. As extracellular signal‐regulated kinase (Erk) and stress‐activated protein kinase/c‐Jun N‐terminal kinase (SAPK/JNK) phosphorylation may induce Fos and Jun gene transcription and activator protein‐1 (AP‐1) DNA binding, the activation of Erk1, Erk2, p38, and SAPK/JNK was examined in the nucleus tractus solitarii and neocortex during hypoxia and following administration of MK‐801. Hypoxia enhanced Erk1, Erk2, and p38 activity in the cortex, but not in the nucleus tractus solitarii. Increased phosphorylation of SEK1 and SAPK/JNK‐2 occurred in the nucleus tractus solitarii during hypoxia, whereas both SAPK/JNK‐1 and SAPK/JNK‐2 were recruited in cortex. MK‐801 attenuated hypoxia‐induced SEK1, SAPK/JNK‐2, and AP‐1 binding in the nucleus tractus solitarii, and the widespread activation of all MAP kinases in the cortex was also attenuated. We conclude that in conscious rats, a moderate hypoxic stimulus elicits NMDA‐dependent widespread mitogenactivated protein kinase activation in cortex, but selective SAPK/JNK‐2 and AP‐1 activation in the nucleus tractus solitarii, thereby suggesting a functional role for the SAPK/JNK‐2‐AP‐1 pathway.
The Non‐NMDA Glutamate Receptor Antagonists 6‐Cyano‐7‐Nitroquinoxaline‐2,3‐dione and 2,3‐Dihydroxy‐6‐Nitro‐7‐Sulfamoylbenzo(f)quinoxaline, but Not NMDA Antagonists, Block the Intrastriatal Neurotoxic Effect of MPP+
Authors: Merino M. , Vizuete M. L. , Cano J. , Machado A.
Published: March 2003

Abstract : Altered glutamatergic neurotransmission appears to be

central to the pathophysiology of Parkinson's disease ; consequently,

considerable effort has been made to elucidate neuroprotective mechanisms

against such toxicity. In the present study, the possible neuroprotective

effect of glutamate receptor antagonists against MPP+ neurotoxicity

on dopaminergic terminals of rat striatum was investigated. Different doses of

glutamate receptor antagonists were coinfused with 1.5 μg of

MPP+ into the striatum ; kynurenic acid, a nonselective antagonist

of glutamate receptors (30 and 60 nmol), partially protected dopaminergic

terminal degeneration in terms of rescue of dopamine levels and tyrosine

hydroxylase immunohistochemistry. Dizocilpine, a channel blocker of the NMDA

receptor (1, 4, and 8 nmol), and 7‐chlorokynurenic acid, a selective

antagonist at the glycine site of the NMDA receptor (1 and 10 nmol), failed to

protect dopaminergic terminals from MPP+ toxicity. However,

6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (0.5 and 1 nmol) and

2,3‐dihydroxy‐6‐nitro‐7‐sulfamoylbenzo(f)quinoxaline (1 nmol), two

AMPA‐kainate receptor antagonists, protected against MPP+ toxicity.

Our findings suggest that the toxic effects of MPP+ on dopaminergic terminals are not mediated through a direct interaction with the NMDA subtype of glutamate receptor, but with the AMPA‐kainate subtype.
Role of the Outward Delayed Rectifier K+ Current in Ceramide‐Induced Caspase Activation and Apoptosis in Cultured Cortical Neurons
Authors: Yu Shan Ping , Yeh Chen‐Hsiung , Gottron Frank , Wang Xin , Grabb Margaret C. , Choi Dennis W.
Published: March 2003

Abstract : We studied the novel hypothesis that an upmodulation of channels for outward delayed rectifier K+ current (Iκ) plays a key role in ceramide‐induced neuronal apoptosis. Exposure for 6‐10 h to the membrane‐permeable C2‐ceramide (25 μM) or to sphingomyelinase (0.2 unit/ml), but not to the inactive ceramide analogue C2‐dihydroceramide (25 μM), enhanced the whole‐cell Iκ current without affecting the transient A‐type K+ current and increased caspase activity, followed by neuronal apoptosis 24 h after exposure onset. Tetraethylammonium (TEA) or 4‐chloro‐N,N‐diethyl‐N‐heptylbenzenebutanaminium tosylate (clofilium), at concentrations inhibiting Iκ, attenuated the C2‐ceramide‐induced caspase‐3‐like activation as well as neuronal apoptosis. Raising extracellular K+ to 25 mM similarly blocked the C2‐ceramide‐induced cell death ; the neuroprotection by 25 mM K+ or TEA was not eliminated by blocking voltage‐gated Ca2+ channels. An inhibitor of tyrosine kinases, herbimycin A (10 nM) or lavendustin A (0.1‐1 μM), suppressed Iκ enhancement and/or apoptosis induced by C2‐ceramide. It is suggested that ceramide‐induced Iκ current enhancement is mediated by tyrosine phosphorylation and plays a critical role in neuronal apoptosis.
Aberrant Copper Chemistry as a Major Mediator of Oxidative Stress in a Human Cellular Model of Amyotrophic Lateral Sclerosis
Authors: Gabbianelli Roberta , Ferri Alberto , Rotilio Giuseppe , Carrì Maria Teresa
Published: March 2003

Abstract : We have investigated the response to oxidative stress in a model system obtained by stable transfection of the human neuroblastoma cell line SH‐SY5Y with plasmids directing constitutive expression of either wild‐type human Cu,Zn superoxide dismutase or a mutant of this enzyme (H46R) associated with familial amyotrophic lateral sclerosis. We report that expression of mutant H46R Cu,Zn superoxide dismutase induces a selective increase in paraquat sensitivity that is reverted by addition of d‐penicillamine. Furthermore, expression of this mutant enzyme affects the activity of the endogenous wild‐type enzyme both in basal conditions and in copper overloading experiments. Our data indicate that aberrant metal chemistry of this mutant enzyme is the actual mediator of oxidative stress and that concurrent impairment of the activity of wild‐type endogenous enzyme compromises the cell’s ability to respond to oxidative stress.
The Mood‐Stabilizing Agents Lithium and Valproate RobustlIncrease the Levels of the Neuroprotective Protein bcl‐2 in the CNS
Authors: Chen Guang , Zeng Wei‐Zhang , Yuan Pei‐Xiong , Huang Li‐Dong , Jiang Yi‐Ming , Zhao Zhen‐Hua , Manji Husseini K.
Published: March 2003

Abstract : Differential display of mRNA was used to identify concordant changes in gene expression induced by two mood‐stabilizing agents, lithium and valproate (VPA). Both treatments, on chronic administration, increased mRNA levels of the transcription factor polyomavirus enhancer‐binding protein (PEBP) 2β in frontal cortex (FCx). Both treatments also increased the DNA binding activity of PEBP2αβ and robustly increased the levels of bcl‐2 (known to be transcriptionally regulated by PEBP2) in FCx. Immunohistochemical studies revealed a marked increase in the number of bcl‐2‐immunoreactive cells in layers 2 and 3 of FCx. These novel findings represent the first report of medication‐induced increases in CNS bcl‐2 levels and may have implications not only for mood disorders, but also for long‐term treatment of various neurodegenerative disorders.
Fyn Tyrosine Kinase Reduces the Ethanol Inhibition of Recombinant NR1/NR2A but Not NR1/NR2B NMDA Receptors Expressed in HEK 293 Cells
Authors: Anders Douglas L. , Blevins Tana , Sutton Greg , Swope Sheridan , Chandler L. Judson , Woodward John J.
Published: March 2003

Abstract: NMDA receptors are potentiated by phosphorylation in a subunit‐ and kinase‐specific manner. Both native and recombinant NMDA receptors are inhibited by behaviorally relevant concentrations of ethanol. Whether the phosphorylation state of individual subunits modulates the ethanol sensitivity of these receptors is not known. In this study, the effects of Fyn tyrosine kinase on the ethanol sensitivity of specific recombinant NMDA receptors expressed in HEK 293 cells were investigated. Whole‐cell mode patch clamp and ratiometric calcium imaging demonstrated that the degree of ethanol inhibition of NR1/NR2B receptors was unaffected by Fyn tyrosine kinase. In contrast, the inhibition of NR1/NR2A receptors by ethanol (100 mM) was significantly reduced under conditions of enhanced Fyn‐mediated tyrosine phosphorylation of the NR2A subunit. This effect was not observed at lower concentrations of ethanol (≤ 50 mM). These results suggest that tyrosine phosphorylation of specific NMDA receptors by Fyn tyrosine kinase may regulate the sensitivity of these receptors to the sedative/hypnotic concentrations of ethanol.
The Sulfate Moieties of Glycosaminoglycans Are Critical for the Enhancement of β‐Amyloid Protein Fibril Formation
Authors: Castillo Gerardo M. , Lukito Widia , Wight Thomas N. , Snow Alan D.
Published: March 2003

Abstract: Our previous studies have demonstrated that perlecan and perlecan‐derived glycosaminoglycans (GAGs) not only bind β‐amyloid protein (Aβ) 1‐40 and 1‐42, but are also potent enhancers of Aβ fibril formation and stabilize amyloid fibrils once formed. However, it was not determined which moieties in perlecan heparan sulfate GAG chains may be responsible for the observed effects and whether other GAGs were also capable of a similar enhancement of Aβ fibril formation as observed with perlecan GAGs. In the present study, thioflavin T fluorometry (over a 1‐week period) was used to extend our previous studies and to test the hypothesis that the sulfate moiety is critical for the enhancing effects of heparin/heparan sulfate GAGs on Aβ 1‐40 fibrillogenesis. This hypothesis was confirmed when removal of all sulfates from heparin (i.e., completely desulfated N‐acetylated heparin) led to a complete loss in the enhancement of Aβ fibrillogenesis as demonstrated in both thioflavin T fluorometry and Congo red staining studies. On the other hand, removal of O‐sulfate from heparin (i.e., completely desulfated N‐sulfated heparin), and to a lesser extent N‐sulfate (i.e., N‐desulfated N‐acetylated heparin), resulted in only a partial loss of the enhancement of Aβ 1‐40 fibril formation. These studies indicate that the sulfate moieties of GAGs are critical for enhancement of Aβ amyloid fibril formation. In addition, other sulfated molecules such as chondroitin‐4‐sulfate, dermatan sulfate, dextran sulfate, and pentosan polysulfate all significantly enhanced (greater than twofold by 3 days) Aβ amyloid fibril formation. These latter findings indicate that deposition and accumulation of other GAGs at sites of Aβ amyloid deposition in Alzheimer’s disease brain may also participate in the enhancement of Aβ amyloidosis.
Phosphorylation of Serine‐880 in GluR2 by Protein Kinase C Prevents Its C Terminus from Binding with Glutamate Receptor‐Interacting Protein
Authors: Matsuda Shinji , Mikawa Sumiko , Hirai Hirokazu
Published: March 2003

Abstract : Phosphorylation of the glutamate receptor is an important

mechanism of synaptic plasticity. Here, we show that the C terminus of GluR2

of the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor

is phosphorylated by protein kinase C and that serine‐880 is the major

phosphorylation site. This phosphorylation also occurs in human embryonic

kidney (HEK) cells by addition of 12‐O‐tetradecanoylphorbol 13‐acetate. Our immunoprecipitation experiment revealed that the phosphorylation of serine‐880 in GluR2 drastically reduced the affinity for glutamate receptor‐interacting protein (GRIP), a synaptic PDZ domain‐containing protein, in vitro and in HEK cells. This result suggests that modulation of serine‐880 phosphorylation in GluR2 controls the clustering of AMPA receptors at excitatory synapses and consequently contributes to synaptic plasticity.
Changes of the Trans‐Activating Potential of AP‐1 Transcription Factor During Cyclosporin A‐Induced Apoptosis of Glioma and Cells Are Mediated by Phosphorylation and Alterations of AP‐1 Composition
Authors: Pyrzynska Beata , Mosieniak Grazyna , Kaminska Bozena
Published: March 2003

Abstract: Although the AP‐1 transcription factor is known to play a role in cell proliferation and activation, it is also involved in apoptosis of cells in response to stress, DNA‐damaging agents, or lack of survival signals. To understand how AP‐1 might contribute to distinct biological processes, we tested a hypothesis that changes in AP‐1 composition or phosphorylation state modulate its transcriptional activity during cyclosporin A‐induced apoptosis of glioma cells. The induction of AP‐1 DNA binding activity composed of c‐Jun, JunB, JunD, and ATF‐2 proteins preceded apoptosis. The compositional changes of AP‐1 were associated with an elevation of c‐Jun and JunB protein levels and the appearance of phosphorylated c‐Jun and ATF‐2 at 15‐40 h posttreatment. Immunocytochemistry and staining with Hoechst 33258 revealed an accumulation of phosphorylated c‐Jun protein in apoptotic cells. Because c‐Jun expression and transcriptional activity are stimulated by phosphorylation at Ser63/73 by c‐Jun N‐terminal kinase (JNK), we measured JNK activities. We found prolonged induction of JNK activity in extracts from cyclosporin‐treated cells, which suggests an involvement of persistent JNK activation in the initiation of glioma cell apoptosis. We provided evidence that variations in AP‐1 composition and phosphorylation resulted in modification of trans‐activating potential toward different promoters. Whereas collagenase AP1/TRE‐dependent transcription was down‐regulated during apoptosis, Fas ligand promoter became activated.
Rat α1‐Macroglobulin Enhances Nerve Growth Factor‐Promoted Neurite Outgrowth, TrkA Phosphorylation, and Gene Expression of Pheochromocytoma PC12 Cells
Authors: Lee Paek‐Gyu , Koo Peter H.
Published: March 2003

Abstract: Monoamine‐activated human α2‐macroglobulin (α2M) has been previously demonstrated to inhibit TrkA‐, TrkB‐, and TrkC‐mediated signal transduction. Rat α1‐macroglobulin (α1M) and α2M are structural homologues of human α2M, but rat α1M is distinctly different from rat α2M in many ways and its role in the mammalian nervous system is unknown. In this report, monoamine‐activated rat α1M was demonstrated to enhance in a dose‐dependent manner nerve growth factor (NGF)‐promoted neurite outgrowth in pheochromocytoma PC12 cells. Monoamine‐activated α1M by itself, however, was neither neurotrophic nor mitogenic to PC12 cells. To investigate further its possible mode of action, the ability of monoamine‐activated α1M and normal α1M to bind and to activate the NGF receptor (TrkA) was investigated. Monoamine‐activated α1M formed a more stable complex with TrkA than normal α1M, but the binding of monoamine‐activated α1M to TrkA was adversely affected by prior stimulation of TrkA with NGF. In addition, monoamine‐activated α1M enhanced the NGF‐promoted TrkA phosphorylation and up‐regulated the expression of NGF‐inducible immediate‐early genes (c‐jun and NGFI‐A) and delayed‐response genes (SCG10 and transin) in PC12 cells; normal α1M, in contrast, produced little or no effect. This study demonstrates that α1M, the constitutive form of α‐macroglobulin in the rat, possesses the ability to promote NGF‐mediated differentiation in PC12 cells, possibly via its direct action on TrkA receptors and TrkA‐mediated signal transduction and gene expression.
Effect of Multiple Serine/Alanine Mutations in the Transmembrane Spanning Region V of the D2 Dopamine Receptor on Ligand Binding
Authors: Coley Clare , Woodward Robert , Johansson Anette M. , Strange Philip G. , Naylor Louise H.
Published: March 2003

Abstract: Three conserved serine residues (Ser193, Ser194, and Ser197) in transmembrane spanning region (TM) V of the D2 dopamine receptor have been mutated to alanine, individually and in combination, to explore their role in ligand binding and G protein coupling. The multiple Ser → Ala mutations had no effect on the binding of most antagonists tested, including [3H]spiperone, suggesting that the multiple mutations did not affect the overall conformation of the receptor protein. Double or triple mutants containing an Ala197 mutation showed a decrease in affinity for domperidone, whereas Ala193 mutants showed an increased affinity for a substituted benzamide, remoxipride. However, dopamine showed large decreases in affinity (>20‐fold) for each multiple mutant receptor containing the Ser193 Ala mutation, and the high‐affinity (coupled) state of the receptor (in the absence of GTP) could not be detected for any of the multiple mutants. A series of monohydroxylated phenylethylamines and aminotetralins was tested for their binding to the native and multiple mutant D2 dopamine receptors. The results obtained suggest that Ser193 interacts with the hydroxyl of S‐5‐hydroxy‐2‐dipropylaminotetralin (OH‐DPAT) and Ser197 with the hydroxyl of R‐5‐OH‐DPAT. We predict that Ser193 interacts with the hydroxyl of R‐7‐OH‐DPAT and the 3‐hydroxyl (m‐hydroxyl) of dopamine. Therefore, the conserved serine residues in TMV of the D2 dopamine receptor are involved in hydrogen bonding interactions with selected antagonists and most agonists tested and also enable agonists to stabilise receptor‐G protein coupling.
Phorbol Ester Activation of the Neuronal Nicotinic Acetylcholine Receptor α7 Subunit Gene
Authors: Carrasco‐Serrano Carmen , Viniegra Salvador , Ballesta Juan J. , Criado Manuel
Published: March 2003

Abstract:α‐Bungarotoxin‐sensitive neuronal nicotinic acetylcholine receptors from bovine adrenomedullary chromaffin cells are up‐regulated by long‐term exposure to phorbol esters. The rise in receptor density is paralleled by an increase in transcripts corresponding to the α7 subunit, which is a component of this receptor subtype. Transcriptional activation of the α7 subunit gene is evidenced in reporter gene transfection experiments, in which phorbol esters increase α7 promoter activity by up to 14‐fold. About 80% of this activation is abolished when at least two of the three sites for the immediate‐early transcription factor Egr‐1, present in the proximal promoter region of the α7 subunit gene, are mutated simultaneously. In addition, phorbol esters elevate both Egr‐1 mRNA and Egr‐1 protein levels in chromaffin cells, whereas electrophoretic mobility shift assays show that the Egr‐1 component of the complexes that originate at the α7 promoter increases in cells treated with phorbol esters. These results suggest that the transcription factor Egr‐1 is involved in triggering expression of α‐bungarotoxin‐sensitive nicotinic receptors in response to external stimuli, such as the ones resulting from phorbol ester treatment, and support our previous hypothesis that the α7 subunit gene is one of the specific targets for Egr‐1.
A Proteolipid Protein‐Specific Pre‐mRNA (Ppm‐1) Contains Intron 3 and Is Up‐Regulated During Myelination in the CNS
Authors: Vouyiouklis Demetrius A. , Barrie Jennifer A. , Griffiths Ian R. , Thomson Christine E.
Published: March 2003

Abstract: Alternative splicing of the precursor for messenger RNA
(pre‐mRNA) is a common process utilised by higher eukaryotes to modulate gene
expression. A single primary transcript may generate several proteins with
distinct functions, expressed in tissue‐specific, developmental patterns. This
article describes an oligodendrocyte‐specific pre‐mRNA product of proteolipid
protein gene (Plp) transcription, which is the precursor for
Plp but not Dm20 mRNA in the CNS. This Plp‐specific
pre‐mRNA (Ppm‐1) includes the intact intron 3 of the Plp
gene. It is first expressed during active myelination, and it localises to the
nucleus of oligodendrocytes, in both normal and jimpy (jp) murine
CNS. In addition to mouse, Ppm‐1 is found also in rat and dog, but
not toad or trout. Our work suggests that alternative splicing of the
Plp gene primary transcript follows a branching pattern, resulting in
the presence of at least one Plp isoform‐specific pre‐mRNA molecule,
Ppm‐1. Therefore, Dm20 mRNA may be the product of a divergent set of pre‐mRNA splicing events.
Differential Regulation of Cyclin D1 and D3 Expression in the Control of Astrocyte Proliferation Induced by Endothelin‐1
Authors: Teixeira Alexandra , Chaverot Nathalie , Strosberg A. Donny , Cazaubon Sylvie
Published: March 2003

Abstract: We have previously shown that the mitogenic effect of endothelin‐1 (ET‐1) in primary astrocytes is dependent on activation of both extracellular signal‐regulated kinase (ERK)‐ and cytoskeleton (CSK)‐dependent pathways. In this study, we evaluated the contribution of each of these pathways to the expression and activation of proteins mediating cell cycle progression. Our results suggest that ET‐1‐induced expression of cyclins D1 and D3 is dependent on the ERK‐ and CSK‐dependent pathways, respectively; moreover, a decrease in the levels of the cyclin‐dependent kinase inhibitor (CKI) p27 was observed as a consequence of ERK activation. Expression of both cyclins D1 and D3 together with a decrease in the p27 levels are essential for retinoblastoma protein (pRB) phosphorylation and cyclin A expression. Furthermore, the molecular events responsible for cell—cell contact inhibition of astrocyte proliferation were found to be independent of the mitogenic pathways leading to D‐type cyclin expression. Cell growth arrest in confluent astrocytes was found to be correlated with increased expression of CKI p21, resulting in inhibition of D‐type cyclin‐associated pRB phosphorylation and cyclin A expression. Taken together, these results indicate that cyclins D1 and D3, which constitute the key mediators of the proliferative response of primary astrocytes to ET‐1, are regulated by distinct signaling pathways.
Interaction Among Mitochondria, Mitogen‐Activated Protein Kinases, and Nuclear Factor‐κB in Cellular Models of Parkinson's Disease
Authors: Cassarino David S. , Halvorsen Erik M. , Swerdlow Russell H. , Abramova Nicole N. , Parker W. Davis , Sturgill Thomas W. , Bennett James P.
Published: March 2003

Abstract: Oxidative stress induced by acute complex I inhibition with 1‐methyl‐4‐phenylpyridinium ion activated biphasically the stress‐activated c‐Jun N‐terminal kinase (JNK) and the early transcription factor nuclear factor‐κB (NF‐κB) in SH‐SY5Y neuroblastoma cells. Early JNK activation was dependent on mitochondrial adenine nucleotide translocator (ANT) activity, whereas late‐phase JNK activation and the cleavage of signaling proteins Raf‐1 and mitogen‐activated protein kinase (MAPK) kinase (MEK) kinase (MEKK)‐1 appeared to be ANT‐independent. Early NF‐κB activation depended on MEK, later activation required an intact electron transport chain (ETC), and Parkinson's disease (PD) cybrid (mitochondrial transgenic cytoplasmic hybrid) cells had increased basal NF‐κB activation. Mitochondria appear capable of signaling ETC impairment through MAPK modules and inducing protective NF‐κB responses, which are increased by PD mitochondrial genes amplified in cybrid cells. Irreversible commitment to apoptosis in this cell model may derive from loss of Raf‐1 and cleavage/activation of MEKK‐1, processes reported in other models to be caspase‐mediated. Therapeutic strategies that reduce mitochondrial activation of proapoptotic MAPK modules, i.e., JNK, and enhance survival pathways, i.e., NF‐κB, may offer neuroprotection in this debilitating disease.
rTLE3, a Newly Identified Transducin‐Like Enhancer of Split, Is Induced by Depolarization in Brain
Authors: Feldman Jonathan D. , Vician Linda , Crispino Marianna , Hoe Warren , Baudry Michel , Herschman Harvey R.
Published: March 2003

Abstract: The transducin‐like enhancers of split are a family of mammalian proteins that share sequence homology with the Drosophila protein Groucho. Using representational difference analysis, we isolated the cDNA for a previously unidentified gene, rTLE3 (rat transducin‐like enhancer of split 3), as a sequence induced by depolarization and forskolin, but not by neurotrophins or growth factors, in PC12 pheochromocytoma cells. rTLE3 encodes the protein rTLE3, a 764‐amino acid orthologue of mouse and human TLE3. R‐esp2, the gene encoding the closest related rat protein, is not induced by any of the four treatments in PC12 cells. rTLE3 and R‐esp2 have different patterns of expression in the adult rat CNS and other tissues. After systemic administration of kainic acid, rTLE3 is induced specifically in the dentate gyrus of the hippocampus. We propose that members of the transducin‐like enhancer of split family of proteins may have distinct functions in the mature CNS, in addition to their functions during development.