bluuebunny/crossref_metadata_2025 huggingface dataset:
Different Effects on Fast Exocytosis Induced by Synaptotagmin 1 and 2 Isoforms and Abundance But Not by Phosphorylation
Authors: Nagy Gábor , Kim Jun Hee , Pang Zhiping P. , Matti Ulf , Rettig Jens , Südhof Thomas C. , Sørensen Jakob B.
Published: January 2006

Synaptotagmins comprise a large protein family, of which synaptotagmin 1 (Syt1) is a Ca2+sensor for fast exocytosis, and its close relative, synaptotagmin 2 (Syt2), is assumed to serve similar functions. Chromaffin cells express Syt1 but not Syt2. We compared secretion from chromaffin cells from Syt1 null mice overexpressing either Syt isoform. High time-resolution capacitance measurement showed that Syt1 null cells lack the exocytotic phase corresponding to the readily-releasable pool (RRP) of vesicles. Comparison with the amperometric signal confirmed that the missing phase of exocytosis consists of catecholamine-containing vesicles. Overexpression of Syt1 rescued the RRP and increased its size above wild-type values, whereas the size of the slowly releasable pool decreased, indicating that the availability of Syt1 regulates the relative size of the two releasable pools. The RRP was also rescued by Syt2 overexpression, but the kinetics of fusion was slightly slower than in cells expressing Syt1. Biochemical experiments showed that Syt2 has a slightly lower Ca2+affinity for phospholipid binding than Syt1 because of a difference in the C2A domain. These data constitute evidence for the function of Syt1 and Syt2 as alternative, but not identical, calcium-sensors for RRP fusion. By overexpression of Syt1 mutated in the shared PKC/calcium/calmodulin-dependent kinase phosphorylation site, we show that phorbol esters act independently and upstream of Syt1 to regulate the size of the releasable pools. We conclude that exocytosis from mouse chromaffin cells can be modified by the differential expression of Syt isoforms and by Syt abundance but not by phosphorylation of Syt1.
Single Transmembrane Domain Insulin-Like Growth Factor-II/Mannose-6-Phosphate Receptor Regulates Central Cholinergic Function by Activating a G-Protein-Sensitive, Protein Kinase C-Dependent Pathway
Authors: Hawkes Cheryl , Jhamandas Jack H. , Harris Kim H. , Fu Wen , MacDonald Richard G. , Kar Satyabrata
Published: January 2006

The insulin-like growth factor-II/mannose-6-phosphate (IGF-II/M6P) receptor is a single-pass transmembrane glycoprotein that plays an important role in the intracellular trafficking of lysosomal enzymes and endocytosis-mediated degradation of IGF-II. However, its role in signal transduction after IGF-II binding remains unclear. In the present study, we report that IGF-II/M6P receptor in the rat brain is coupled to a G-protein and that its activation by Leu27IGF-II, an analog that binds rather selectively to the IGF-II/M6P receptor, potentiates endogenous acetylcholine release from the rat hippocampal formation. This effect is mediated by a pertussis toxin (PTX)-sensitive GTP-binding protein and is dependent on protein kinase Cα (PKCα)-induced phosphorylation of downstream substrates, myristoylated alanine-rich C kinase substrate, and growth associated protein-43. Additionally, treatment with Leu27IGF-II causes a reduction in whole-cell currents and depolarization of cholinergic basal forebrain neurons. This effect, which is blocked by an antibody against the IGF-II/M6P receptor, is also sensitive to PTX and is mediated via activation of a PKC-dependent pathway. These results together revealed for the first time that the single transmembrane domain IGF-II/M6P receptor expressed in the brain is G-protein coupled and is involved in the regulation of central cholinergic function via the activation of specific intracellular signaling cascades.
Direct Involvement of Orexinergic Systems in the Activation of the Mesolimbic Dopamine Pathway and Related Behaviors Induced by Morphine
Authors: Narita Minoru , Nagumo Yasuyuki , Hashimoto Seiko , Narita Michiko , Khotib Junaidi , Miyatake Mayumi , Sakurai Takeshi , Yanagisawa Masashi , Nakamachi Tomoya , Shioda Seiji , Suzuki Tsutomu
Published: January 2006

In this study, we investigated the role of orexinergic systems in dopamine-related behaviors induced by the μ-opioid receptor agonist morphine in rodents. Extensive coexpression of tyrosine hydroxylase with orexin receptors was observed in the mouse ventral tegmental area (VTA). The levels of dopamine and its major metabolites in the nucleus accumbens were markedly increased by the microinjection of orexin A and orexin B into the VTA. The subcutaneous morphine-induced place preference and hyperlocomotion observed in wild-type mice were abolished in mice that lacked the prepro-orexin gene. An intra-VTA injection of a selective orexin receptor antagonist SB334867A [1-(2-methylbenzoxazol-6-yl)-3-[1.5]naphthyridin-4-yl urea] significantly suppressed the morphine-induced place preference in rats. Furthermore, the increased level of dialysate dopamine produced by morphine in the mouse brain was significantly decreased by deletion of the prepro-orexin gene. These findings provide new evidence that orexin-containing neurons in the VTA are directly implicated in the rewarding effect and hyperlocomotion induced by morphine through activation of the mesolimbic dopamine pathway in rodents.
Transcranial Magnetic Stimulation of Frontal Oculomotor Regions during Smooth Pursuit
Authors: Gagnon Danny , Paus Tomás̆ , Grosbras Marie-Helène , Pike G. Bruce , O'Driscoll Gillian A.
Published: January 2006

Both the frontal eye fields (FEFs) and supplementary eye fields (SEFs) are known to be involved in smooth pursuit eye movements. It has been shown recently that stimulation of the smooth-pursuit area of the FEF [frontal pursuit area (FPA)] in monkey increases the pursuit response to unexpected changes in target motion during pursuit. In the current study, we applied transcranial magnetic stimulation (TMS) to the FPA and SEF in humans during sinusoidal pursuit to assess its effects on the pursuit response to predictable, rather than unexpected, changes in target motion. For the FPA, we found that TMS applied immediately before the target reversed direction increased eye velocity in the new direction, whereas TMS applied in mid-cycle, immediately before the target began to slow, decreased eye velocity. For the SEF, TMS applied at target reversal increased eye velocity in the new direction but had no effect on eye velocity when applied at mid-cycle. TMS of the control region (leg region of the somatosensory cortex) did not affect eye velocity at either point. Previous stimulation studies of FPA during pursuit have suggested that this region is involved in controlling the gain of the transformation of visual signals into pursuit motor commands. The current results suggest that the gain of the transformation of predictive signals into motor commands is also controlled by the FPA. The effect of stimulation of the SEF is distinct from that of the FPA and suggests that its role in sinusoidal pursuit is primarily at the target direction reversal.
Estrogen Prevents Neuroprotection by Caffeine in the Mouse 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine Model of Parkinson's Disease
Authors: Xu Kui , Xu Yuehang , Brown-Jermyn Deborah , Chen Jiang-Fan , Ascherio Alberto , Dluzen Dean E. , Schwarzschild Michael A.
Published: January 2006

Epidemiological studies have strongly linked caffeine consumption with a reduced risk of developing Parkinson's disease (PD) in men. Interestingly, in women, this inverse association is present only in those who have not taken postmenopausal estrogens, suggesting an interaction between the influences of estrogen and caffeine use on the risk of PD. To explore a possible biological basis for this interaction, we systematically investigated how the neuroprotective effect of caffeine is influenced by gender, ovariectomy (OVX), and then exogenous estrogen in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. (1) Caffeine treatment produced a dose-dependent attenuation of MPTP-induced striatal dopamine loss in both young and retired breeder (RB) male, but not female, mice. (2) In female mice (both young and RB), caffeine was less potent or altogether ineffective as a neuroprotectant after sham surgery compared to OVX or after OVX plus estrogen replacement compared to OVX plus placebo treatment. (3) Estrogen treatment also prevented the protection of caffeine against dopamine loss in young male mice. (4) Consistent with the putative protective effect of estrogen, female and OVX plus estrogen mice were relatively resistant to MPTP toxicity compared to male and OVX plus placebo mice, respectively. (5) There was no overall difference in brain levels of caffeine and its metabolites between OVX plus placebo and OVX plus estrogen mice. Together, these results suggest that estrogen can occlude and thereby prevent the neuroprotective effect of caffeine in a model of PD neurodegeneration, supporting a biological basis for the interaction between estrogen and caffeine in modifying the risk of PD.
Alix, Making a Link between Apoptosis-Linked Gene-2, the Endosomal Sorting Complexes Required for Transport, and Neuronal DeathIn Vivo
Authors: Mahul-Mellier Anne-Laure , Hemming Fiona J. , Blot Béatrice , Fraboulet Sandrine , Sadoul Rémy
Published: January 2006

Alix/apoptosis-linked gene-2 (ALG-2)-interacting protein X is an adaptor protein involved in the regulation of the endolysosomal system through binding to endophilins and to endosomal sorting complexes required for transport (ESCRT) proteins, TSG101 and CHMP4b. It was first characterized as an interactor of ALG-2, a calcium-binding protein necessary for cell death, and several observations suggest a role for Alix in controlling cell death. We used electroporation in the chick embryo to test whether overexpressed wild-type or mutated Alix proteins influence cell deathin vivo. We show that Alix overexpression is sufficient to induce cell death of neuroepithelial cells. This effect is strictly dependent on its capacity to bind to ALG-2. On the other hand, expression of Alix mutants lacking the ALG-2 or the CHMP4b binding sites prevents early programmed cell death in cervical motoneurons at day 4.5 of chick embryo development. This protection afforded by Alix mutants was abolished after deletion of the TSG101, but not of the endophilin, binding sites. Our results suggest that the interaction of the ALG-2/Alix complex with ESCRT proteins is necessary for naturally occurring death of motoneurons. Therefore, Alix represents a molecular link between the endolysosomal system and the cell death machinery.
Aldosterone Target Neurons in the Nucleus Tractus Solitarius Drive Sodium Appetite
Authors: Geerling Joel C. , Engeland William C. , Kawata Mitsuhiro , Loewy Arthur D.
Published: January 2006

Sodium appetite can be enhanced by the adrenal steroid aldosterone via an unknown brain mechanism. A novel group of neurons in the nucleus tractus solitarius expresses the enzyme 11-β-hydroxysteroid dehydrogenase type 2, which makes them selectively responsive to aldosterone. Their activation parallels sodium appetite in different paradigms of salt loss even in the absence of aldosterone. These unique aldosterone target neurons may represent a previously unrecognized central convergence point at which hormonal and neural signals can be integrated to drive sodium appetite.
Axonal Growth and Guidance Defects inFrizzled3Knock-Out Mice: A Comparison of Diffusion Tensor Magnetic Resonance Imaging, Neurofilament Staining, and Genetically Directed Cell Labeling
Authors: Wang Yanshu , Zhang Jiangyang , Mori Susumu , Nathans Jeremy
Published: January 2006

Previous work has identified axonal outgrowth and/or guidance defects in the brain and spinal cord of prenatalFrizzled3(Fz3)–/–mice. To systematically explore the axonal defects inFz3–/–mice and to compare techniques for the global assessment of axon tracts in the developing mouse, we have analyzed wild-type andFz3–/–brains using (1) diffusion tensor magnetic resonance imaging (μDTI), (2) neurofilament staining, and (3) two genetically directed neuronal labeling methods. Confirming and extending the previous work of Wang et al. (2002), we find that the following structures/tracts are absent or greatly reduced in theFz3–/–brain: the anterior commissure, cerebral peduncle (corticospinal tract), corpus callosum, fornix, internal capsule (thalamocortical and corticothalamic tracts), stria medullaris, stria terminalis, and hippocampal commissure. An aberrant U-shaped fiber bundle immediately caudal to the optic tract connects the left and right sides of theFz3–/–thalamus and likely represents a default pathway for thalamic axons that failed to enter the internal capsule. At embryonic day 18, labeling of cortical pyramidal cells with a yellow fluorescent protein reporter reveals widespread fragmentation of axons with no apparent loss of pyramidal cell bodies. Fragmentation likely represents one stage in the process that normally eliminates stalled or mistargeted axons. This work demonstrates the usefulness of μDTI and genetically directed neuronal labeling for the analysis of nervous system defects in the mouse.
Kinetics of Cerebral Amyloid Angiopathy Progression in a Transgenic Mouse Model of Alzheimer Disease
Authors: Robbins Elissa M. , Betensky Rebecca A. , Domnitz Sarah B. , Purcell Susan M. , Garcia-Alloza Monica , Greenberg Charles , Rebeck G. William , Hyman Bradley T. , Greenberg Steven M. , Frosch Matthew P. , Bacskai Brian J.
Published: January 2006

Cerebral amyloid angiopathy (CAA), the deposition of cerebrovascular β-amyloid (Aβ) in the walls of arterial vessels, has been implicated in hemorrhagic stroke and is present in most cases of Alzheimer disease. Previous studies of the progression of CAA in humans and animal models have been limited to the comparison of pathological tissue from different brains at single time points. Our objective was to visualize in real time the initiation and progression of CAA inTg2576mice by multiphoton microscopy through cranial windows. Affected vessels were labeled by methoxy-X04, a fluorescent dye that selectively binds cerebrovascular β-amyloid and plaques. With serial imaging sessions spaced at weekly intervals, we were able to observe the earliest appearance of CAA in leptomeningeal arteries as multifocal deposits of band-like Aβ. Over subsequent imaging sessions, we were able to identify growth of these deposits (propagation), as well as appearance of new bands (additional initiation events). Statistical modeling of the data suggested that as the extent of CAA progressed in this vascular bed, there was increased prevalence of propagation over initiation. During the early phases of CAA development, the overall pathology burden progressed at a rate of 0.35% of total available vessel area per day (95% confidence interval, 0.3–0.4%). The consistent rate of disease progression implies that this model is amenable to investigations of therapeutic interventions.
Functional Dissection of a Neuronal Network Required for Cuticle Tanning and Wing Expansion inDrosophila
Authors: Luan Haojiang , Lemon William C. , Peabody Nathan C. , Pohl Jascha B. , Zelensky Paul K. , Wang Ding , Nitabach Michael N. , Holmes Todd C. , White Benjamin H.
Published: January 2006

A subset ofDrosophilaneurons that expresses crustacean cardioactive peptide (CCAP) has been shown previously to make the hormone bursicon, which is required for cuticle tanning and wing expansion after eclosion. Here we present evidence that CCAP-expressing neurons (NCCAP) consist of two functionally distinct groups, one of which releases bursicon into the hemolymph and the other of which regulates its release. The first group, which we call NCCAP-c929, includes 14 bursicon-expressing neurons of the abdominal ganglion that lie within the expression pattern of the enhancer-trap line c929-Gal4. We show that suppression of activity within this group blocks bursicon release into the hemolymph together with tanning and wing expansion. The second group, which we call NCCAP-R, consists of NCCAPneurons outside the c929-Gal4 pattern. Because suppression of synaptic transmission and protein kinase A (PKA) activity throughout NCCAP, but not in NCCAP-c929, also blocks tanning and wing expansion, we conclude that neurotransmission and PKA are required in NCCAP-R to regulate bursicon secretion from NCCAP-c929. Enhancement of electrical activity in NCCAP-R by expression of the bacterial sodium channel NaChBac also blocks tanning and wing expansion and leads to depletion of bursicon from central processes. NaChBac expression in NCCAP-c929 is without effect, suggesting that the abdominal bursicon-secreting neurons are likely to be silent until stimulated to release the hormone. Our results suggest that NCCAPform an interacting neuronal network responsible for the regulation and release of bursicon and suggest a model in which PKA-mediated stimulation of inputs to normally quiescent bursicon-expressing neurons activates release of the hormone.
Expression of a Familial Alzheimer's Disease-Linked Presenilin-1 Variant Enhances Perforant Pathway Lesion-Induced Neuronal Loss in the Entorhinal Cortex
Authors: Lazarov Orly , Peterson Letia D. , Peterson Daniel A. , Sisodia Sangram S.
Published: January 2006

Alzheimer's disease (AD) is characterized by neuronal loss in the hippocampus and entorhinal cortex that is manifested by progressive memory impairment and cognitive decline. Autosomal-dominant, familial forms of AD (FAD) are caused by mutations in genes encoding amyloid precursor protein, presenilin-1 (PS1), and presenilin 2. Although it is established that expression of mutant PS1 variants leads to increased production of highly fibrillogenic amyloidβ42(Aβ42) peptides that deposit in the brains of patients with AD, the mechanism(s) by which Aβ deposition and expression of mutant genes induce lamina- and region-specific vulnerability of neuronal populations is not known. We have examined the hypothesis that expression of transgene-encoded FAD-linked mutant PS1 variants in entorhinal cortex neurons exacerbates the vulnerability of these cells to lesion-induced neuronal loss. To test this notion, we transected the perforant pathway (PP) of transgenic mice harboring either wild-type human PS1 (PS1HWT) or the FAD-linked mutant PS1ΔE9 variant and examined neuronal survival in layer II of the entorhinal cortex (ECL2). Remarkably, PP transections lead to marked reductions in the numbers of ECL2 neurons in the ECL2 of mice expressing mutant PS1, compared with ECL2 neurons in PP-lesioned PS1HWT mice. Finally, and in contrast to studies in nontransgenic mice and in mice expressing PS1HWT, ECL2 neurons that express mutant PS1 and the calcium binding protein calbindin-D28kin ECL2 are also susceptible to lesion-induced neuronal loss. We conclude that expression of FAD-linked mutant PS1 variants enhances the vulnerability of neurons in the entorhinal cortex to PP lesion-induced cytotoxicity.
Foveal Visual Strategy during Self-Motion Is Independent of Spatial Attention
Authors: Wei Min , Angelaki Dora E.
Published: January 2006

Translational self-motion disturbs the stability of retinal images by inducing a pattern of retinal optic flow that cannot be compensated globally by a single eye movement. The eyes must rotate by different amounts, depending on which spatial location needs to be stabilized on the retina. However, compensatory eye movements during steady fixation are always such as to maintain visual acuity on the fovea at the expense of significant image slip on the peripheral retina. We investigated whether such a foveal visual strategy during translation is hard-wired or whether it embeds enough flexibility to also allow for behaviorally relevant objects outside the foveae to be stabilized preferentially on the retinas. Monkeys were moved forward or backward and leftward or rightward passively in darkness while planning a saccade or bar release to peripheral dimmed targets. By comparing the eye movements made during these tasks with those under conditions of steady fixation, we found that the motion-induced eye movements depended only on current fixation. This was true even during the last milliseconds just before a saccade to the peripheral target. We conclude that the foveal stabilization strategy is invariant and solely dependent on current eye position, a strategy that is optimal for both processing speed and efficiency in the extraction of heading information from retinal flow during self-motion.
Placebo-Induced Changes in Spinal Cord Pain Processing
Authors: Matre Dagfinn , Casey Kenneth L. , Knardahl Stein
Published: January 2006

Pain is an essential sensory modality, signaling injury or threat of injury. Pain perception depends on both biological and psychological factors. However, it is not known whether psychological factors modify spinal mechanisms or if its effect is limited to cortical processing. Here, we use a placebo analgesic model to show that psychological factors affect human spinal nociceptive processes. Mechanical hyperalgesia (hypersensitivity) after an injury is attributable to sensitized sensory neurons in the spinal cord. After a 5 min, 46°C heating of the skin, subjects developed areas of mechanical hyperalgesia. This area was smaller in a placebo condition compared with a baseline condition. This result suggests that placebo analgesia affects the spinal cord as well as supra-spinal pain mechanisms in humans and provides strong supporting evidence that placebo analgesia is not simply altered reporting behavior. Central sensitization is thought to mediate the exaggerated pain after innocuous sensory stimulation in several clinical pain conditions that follow trauma and nervous-system injury. These new data indicate that expectation about pain and analgesia is an important component of the cognitive control of central sensitization.
Compensatory Changes in the Noradrenergic Nervous System in the Locus Ceruleus and Hippocampus of Postmortem Subjects with Alzheimer's Disease and Dementia with Lewy Bodies
Authors: Szot Patricia , White Sylvia S. , Greenup J. Lynne , Leverenz James B. , Peskind Elaine R. , Raskind Murray A.
Published: January 2006

In Alzheimer's disease (AD), there is a significant loss of locus ceruleus (LC) noradrenergic neurons. However, functional and anatomical evidence indicates that the remaining noradrenergic neurons may be compensating for the loss. Because the noradrenergic system plays an important role in learning and memory, it is important to determine whether compensation occurs in noradrenergic neurons in the LC and hippocampus of subjects with AD or a related dementing disorder, dementia with Lewy bodies (DLB). We observed profound neuronal loss in the LC in AD and DLB subjects with three major changes in the noradrenergic system consistent with compensation: (1) an increase in tyrosine hydroxylase (TH) mRNA expression in the remaining neurons; (2) sprouting of dendrites into peri-LC dendritic zone, as determined by α2-adrenoreceptors (ARs) and norepinephrine transporter binding sites; and (3) sprouting of axonal projections to the hippocampus as determined by α2-ARs. In AD and DLB subjects, the postsynaptic α1-ARs were normal to elevated. Expression of α1A- and α2A-AR mRNA in the hippocampus of AD and DLB subjects were not altered, but expression of α1D- and α2C-AR mRNA was significantly reduced in the hippocampus of AD and DLB subjects. Therefore, in AD and DLB subjects, there is compensation occurring in the remaining noradrenergic neurons, but there does appear to be a loss of specific AR in the hippocampus. Because changes in these noradrenergic markers in AD versus DLB subjects were similar (except neuronal loss and the increase in TH mRNA were somewhat greater in DLB subjects), the presence of Lewy bodies in addition to plaques and tangles in DLB subjects does not appear to further affect the noradrenergic compensatory changes.
NMDA Receptors in Layer 4 Spiny Stellate Cells of the Mouse Barrel Cortex Contain the NR2C Subunit
Authors: Binshtok Alexander M. , Fleidervish Ilya A. , Sprengel Rolf , Gutnick Michael J.
Published: January 2006

In layer 4 of the somatosensory cortex, the glutamatergic synapses that interconnect spiny stellate (SpS) neurons, which are the major targets of thalamocortical input, differ from most other neocortical excitatory synapses in that they have an extremely large NMDA receptor (NMDAR)-mediated component that is relatively insensitive to voltage-dependent Mg2+blockade. We now report that this unique feature of the NMDA response reflects the distinctive subunit composition of the underlying receptors. We studied NMDAR-mediated miniature EPSCs (mEPSCs) and NMDA channel currents in tangential brain slices of mouse barrel cortex, which exclusively contain layer 4. NMDAR-mediated mEPSCs in SpS neurons were prominent at negative membrane potentials, and NMDA channels in outside-out patches excised from the somata of the same neurons had relatively low conductance and reduced susceptibility to Mg2+block. These are characteristic features of heteromeric NMDAR assemblies that contain the NR2C subunit. Some patches also contained NMDA channels with higher conductance and a greater sensitivity to Mg2+. In the neocortex of transgenic mice in which a β-galactosidase (lacZ) indicator gene was controlled by the NR2C promoter, the lacZ indicator was densely expressed in layer 4. In current-clamp recordings, blockade of NMDARs caused hyperpolarization and an increase in apparent input resistance. Our data demonstrate that the SpS neurons of layer 4 functionally express NR2C subunits; this is the likely explanation for their ability to generate large NMDAR-mediated EPSPs that are effective at resting potential, without previous depolarization.
Tonic Facilitation of Glutamate Release by Presynaptic NR2B-Containing NMDA Receptors Is Increased in the Entorhinal Cortex of Chronically Epileptic Rats
Authors: Yang Jian , Woodhall Gavin L. , Jones Roland S. G.
Published: January 2006

We have shown previously that when postsynaptic NMDA receptors are blocked, the frequency, but not amplitude, of spontaneous EPSCs (sEPSCs) at synapses in the entorhinal cortex is reduced by NMDA receptor antagonists, demonstrating that glutamate release is tonically facilitated by presynaptic NMDA autoreceptors. In the present study, we recorded sEPSCs using whole-cell voltage clamp in neurons in layer V in slices of the rat entorhinal cortex. Using specific antagonists for NR2A [(R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid] and NR2B [(αR, βS)-α-(4-hydroxyphenyl)-β-methyl-4-(phenylmethyl)-1-piperidinepropanol hydrochloride (Ro 25-6981)] subunit-containing receptors, we confirmed that in slices from juvenile rats (4–6 weeks of age), the autoreceptor is predominantly of the NR1–NR2B subtype. In older (4–6 months of age) control animals, the effect of the NR2B antagonist was less marked, suggesting a decline in autoreceptor function with development. In slices from rats (aged 4–6 months) exhibiting spontaneous recurrent seizures induced with a lithium-pilocarpine protocol, Ro 25-6981 again robustly reduced sEPSC frequency. The effect was equal to or greater than that seen in the juvenile slices and much more pronounced than that seen in the age-matched control animals. In all three groups, the NR2A antagonist was without effect on sEPSCs. These results suggest that there is a developmental decrease in NMDA autoreceptor function, which is reversed in a chronic epileptic condition. The enhanced autoreceptor function may contribute to seizure susceptibility and epileptogenesis in temporal lobe structures.
Neuromuscular Synapse Formation in Mice Lacking Motor Neuron- and Skeletal Muscle-Derived Neuregulin-1
Authors: Jaworski Alexander , Burden Steven J.
Published: January 2006

The localization of acetylcholine receptors (AChRs) to the vertebrate neuromuscular junction is mediated, in part, through selective transcription ofAChRsubunit genes in myofiber subsynaptic nuclei. Agrin and the muscle-specific receptor tyrosine kinase, MuSK, have critical roles in synapse-specific transcription, becauseAChRgenes are expressed uniformly in mice lacking either agrin or MuSK. Several lines of evidence suggest that agrin and MuSK stimulate synapse-specific transcription indirectly by regulating the distribution of other cell surface ligands, which stimulate a pathway for synapse-specific gene expression. This putative secondary signal for directingAChRgene expression to synapses is not known, but Neuregulin-1 (Nrg-1), primarily based on its presence at synapses and its ability to induceAChRgene expressionin vitro, has been considered a good candidate. To study the role of Nrg-1 at neuromuscular synapses, we inactivatednrg-1in motor neurons, skeletal muscle, or both cell types, using mice that express Cre recombinase selectively in developing motor neurons or in developing skeletal myofibers. We find that AChRs are clustered at synapses and that synapse-specific transcription is normal in mice lacking Nrg-1 in motor neurons, myofibers, or both cell types. These data indicate that Nrg-1 is dispensable for clustering AChRs and activatingAChRgenes in subsynaptic nuclei during development and suggest that these aspects of postsynaptic differentiation are dependent on Agrin/MuSK signaling without a requirement for a secondary signal.
Tactile Spatial Attention Enhances Gamma-Band Activity in Somatosensory Cortex and Reduces Low-Frequency Activity in Parieto-Occipital Areas
Authors: Bauer Markus , Oostenveld Robert , Peeters Maarten , Fries Pascal
Published: January 2006

We investigated the effects of spatial-selective attention on oscillatory neuronal dynamics in a tactile delayed-match-to-sample task. Whole-head magnetoencephalography was recorded in healthy subjects while dot patterns were presented to their index fingers using Braille stimulators. The subjects' task was to report the reoccurrence of an initially presented sample pattern in a series of up to eight test stimuli that were presented unpredictably to their right or left index finger. Attention was cued to one side (finger) at the beginning of each trial, and subjects performed the task at the attended side, ignoring the unattended side.

After stimulation, high-frequency gamma-band activity (60–95 Hz) in presumed primary somatosensory cortex (S1) was enhanced, whereas alpha- and beta-band activity were suppressed in somatosensory and occipital areas and then rebounded. Interestingly, despite the absence of any visual stimulation, we also found time-locked activation of medial occipital, presumably visual, cortex. Most relevant, spatial tactile attention enhanced stimulus-induced gamma-band activity in brain regions consistent with contralateral S1 and deepened and prolonged the stimulus induced suppression of beta- and alpha-band activity, maximal in parieto-occipital cortex. Additionally, the beta rebound over contralateral sensorimotor areas was suppressed.

We hypothesize that spatial-selective attention enhances the saliency of sensory representations by synchronizing neuronal responses in early somatosensory cortex and thereby enhancing their impact on downstream areas and facilitating interareal processing. Furthermore, processing of tactile patterns also seems to recruit visual cortex and this even more so for attended compared with unattended stimuli.
Water, Atmosphere, and Environmental Governance: A Comprehensive Perspective
Authors: Ferrara Enzo
Published: January 2006

Reflections on Water: New Approaches to Transboundary Conflicts and Cooperation. Joachim Blatter and Helen Ingram. eds. Cambridge, MA: MIT Press, 2001.

Changing the Atmosphere: Expert Knowledge and Environmental Governance. Clark Miller and Paul N. Edwards. eds. Cambridge, MA: MIT Press, 2001.
Banana Wars: Power, Production, and History in the Americas
Authors: Gulbas Lauren E.
Published: January 2006

Banana Wars: Power, Production, and History in the Americas. Steve Striffler and Mark Moberg. eds. Durham, NC: Duke University Press, 2003.
“We Are Not Surviving, We Are Managing”: the constitution of a Nigerian diaspora along the contours of the global economy
Authors: REYNOLDS RACHEL R.
Published: January 2006

This ethnographic piece outlines how the geography of globalization and its socieconomic vicissitudes condition unique life experiences for Nigerian Igbo immigrants in the U.S. The elite class of Igbo people from Nigeria continue to immigrate to the U.S. in large numbers. As professionals, ethnic group members tend to settle in mainstream American neighborhoods, experiencing a high degree of structural integration into global professional workplaces and occupations. Ironically, the same physical and occupational mobility that disperses Igbo elites across the globe and across the U.S. also provides the enhanced means by which Igbo‐speaking people sustain their ethnic organizations and diasporic communities. Professional work, normally in places which are assimilated to the American mainstream despite being extra–Igbo contexts, actually encourage habits of interactive communication that are brought into the service of Igbo community cohesion. In that sense, a geographical distribution that is primarily socio‐economic is also parlayed into a means by which people come together through travel, through literacy, and through synchronous communication technologies.
The Denial of Citizenship: “barbaric” Buenos Aires and the middle‐class imaginary
Authors: GUANO EMANUELA
Published: January 2006

This essay explores how, in the Buenos Aires of neoliberalism, middle‐class residents strove to make sense of their own impoverishment and their disenfranchisement by generating a consensus on how this city's modernity was being eroded by the presence of a mestizo lower class. Through an analysis of the discourse that constructed the urban poor as barbaric (i.e., dangerous, polluting, and foreign), I suggest that this representation not only sought to reinforce the fading social difference between the middle‐ and the lower class, but it also contributed to denying the latter its citizenship in a Buenos Aires that struggled to be modern.
Punta del Este as Global City? competing visions of Uruguayan nationhood in a geography of exclusion
Authors: RENFREW DANIEL
Published: January 2006

This article examines the controversies and struggles surrounding the Uruguayan workers confederation march from Montevideo to the exclusive resort city of Punta del Este in 2002. At stake were competing visions of the present and future direction of Uruguay. Punta del Este is central to the government's project of a “new” Uruguay: a service‐oriented, outward‐looking, and high‐tech regional financial and economic center. The city presents a socially and spatially exclusive setting to showcase this new image, an exclusivity necessary in the face of the contrasting vision the protestors sought to highlight: an Uruguay of growing poverty, inequality and a questionable future.
Gating and Class Relations: the case of a New Delhi “colony”
Authors: WALDROP ANNE
Published: January 2006

During the 1990s an increasing number of New Delhi's elite neighborhoods erected gates with guards at their entrances. A process, which elsewhere has been termed fortification or gating, is unfolding in the city. In the context of changing class relations in urban India this article explores the gating of one centrally located upscale neighbourhood, or “colony,” called Golf Links in New Delhi. In Golf Links, the elite explains the gating as a result of increased crime and untrustworthy servants. In this article it is argued rather that gating must be understood in terms of complex transformations unfolding in Indian cities. The case of Golf Links provides insight into how these changes affect urban Indian class relations.
Study of the early growth and tillering capacity of barley (Hordeum vulgareL.) under changing temperature and light conditions in gradient growth chamber
Authors: Kőszegi B. , Karsai I. , Mészáros K. , Kovács G.
Published: January 2006

The early growth and tillering capacity of two barley (Hordeum vulgare L.) varieties (Dicktoo and Kompolti Korai) were investigated in a gradient growth chamber. The identification of these crop traits is important under organic agricultural conditions in the selection of new varieties for competitiveness against weeds. The results clearly demonstrate that the initial development of the two barley varieties depended considerably on the plant growth conditions. The temperature gradient was found to have the greater effect during early development, causing significant differences in all the traits at all measurement dates. The results indicate that the two varieties differ substantially for two characteristics important for organic farming. As regards tillering ability, Dicktoo appears to be the more desirable type, despite the fact that it is unable to achieve its tillering potential at higher temperatures. Under certain ecological conditions, the relative temperature insensitivity of Kompolti Korai could be an advantage. As far as early development vigour is concerned, Kompolti Korai is clearly a desirable type for organic farming, since it produced rapidly growing, robust plants in all the temperature ranges. From the point of view of organic breeding, a combination of the valuable traits of these two varieties could be the way forward.
Sources of infection and methods of control of Septoria oenotheraein evening primrose (Oenotheraspp.)
Authors: O'Connell M. N. , Kethees Wararajah V. , Fieldsend A. F. , Cullum F. J.
Published: January 2006

Septoria oenotheraeWest. can cause severe damage in overwintered crops of evening primrose (Oenothera spp.), including complete crop loss. Damage would be reduced if the sources of infection could be identified and removed. Examination of seed capsules inoculated with S. oenotheraeshowed that 96% of the pycnidia present were on the outside of the capsules, and seeds bearing pycnidia were only rarely found. However, internal infection of seeds from these capsules was demonstrated by both a blotter test and by culturing on agar media. Immersing seeds in 45°C water for 25 minutes destroyed viable fungal propagules located internally in seeds without reducing seed germination. The pathogen was also shown to overwinter in the pycnidial stage on stems left standing in the field. It is concluded that both internal seed-borne infection and overwintered crop debris are potential sources of infection in commercial seed stocks of evening primrose.
N2fixation in faba bean grown under saline and non-saline conditions using a 15N-tracer technique
Authors: Khalifa K. , Kurdali F.
Published: January 2006

A pot experiment was conducted to study the performance of faba bean and barley growing under saline conditions, in terms of dry matter yield, total N, and percentages and amount of N derived from the soil, fertilizer and atmosphere using a 15N isotope dilution method. Three saline treatments were employed: 1) plants were grown on saline soil and irrigated with saline water (SsWs); 2) plants were grown on saline soil and irrigated with non-saline water (SsWn); and 3) plants were grown on non-saline soil and irrigated with saline water (SnWs). Furthermore, a control treatment was employed by growing the plants on non-saline soil and irrigating them with non-saline water (SnWn). The different salinity treatments reduced plant growth and the reduction was more pronounced in faba bean than in barley. However, the relative growth reduction of plants grown only on saline soil, using non-saline water, did not exceed 50% of the control, whereas the reduction exceeded 50% when plants were grown under completely saline conditions. The percentage of N2fixed (%Ndfa) was not affected negatively by saline conditions.the results clearly demonstrated that the effect of salinity on faba bean was more evident on plant growth than on N2-fixing activity. Further studies are needed to obtain more salt-tolerant faba bean genotypes that possess a higher growth rate. This could simultaneously improve yield and N2fixation under severely saline conditions.
Effect of N management approaches and planting densities on nitrogen accumulation by transplanted rice
Authors: Janaki P. , Thiyagarajan T. M.
Published: January 2006

Field experiments were conducted during 1998 and 1999 in June-September with rice variety ASD18 at the wetland farm, Tamil Nadu Agricultural University, Coimbatore, India to find out theeffect of N management approaches and planting densities on N accumulation by transplanted rice in a split plot design.The main plot consisted of three plant populations (33, 66 and 100 hills m-2) and the sub-plot treatments of five N management approaches. The results revealed thatthe average N uptake in roots and aboveground biomass progressively increased with growth stages. The mean root and aboveground biomass Nuptake were 26.1 to 130.6 and 6.4 to 17.8 kg ha-1, respectively. The N uptake of grain and straw was higher in theSesbania rostratagreen manuring + 150 kg N treatment, but it was not effective in increasing the grain yield. The mean total N uptake was found to be significantly lower at 33 hills m-2(76.9 kg ha-1) and increased with an increase in planting density (100.9 and 117.2 kg ha-1at 66 and 100 hills m-2density). N application had a significant influence on N uptake and the time course of N uptake in all the SPAD-guided N approaches. A significant regression coefficient was observed between the crop N uptake and grain yield. The relationship between cumulative N uptake at the flowering stage and the grain yield was quadratic at all three densities. The N uptake rate (µN) was maximum during the active tillering to panicle initiation period and declined sharply after that. In general, µNincreased with an increase in planting density and the increase was significant up to the panicle initiation to flowering period.thereafter, the N uptake rate was similar at densities of 66 and 100 hills m-2.
Effect of different planting densities on yield and yield components of wild thyme (Thymbra spicatavar. spicata)
Authors: Kizil S. , Tonçer Ö.
Published: January 2006

The study reports the effect of the planting density of wild thyme (Thymbra spicatavar. spicata) on plant height, fresh herbage yield, dry herbage yield, dry leaf yield, essential oil content and essential oil yield. The results show that the highest fresh and dry herbage, dry leaf yield and essential oil yield were obtained from narrow row spacing and in-rows. However, fresh herbage, dry leaf yield and essential oil yield showed a variation of 0.993-1.463 kg m-2, 0.179-0.279 kg m-2and 33.6-50.9 L ha-1, respectively.
Evaluation of regeneration potential in pearl millet
Authors: Kumar R. , Sagar P. , Behl R. K.
Published: January 2006

The regeneration potential of pearl millet, a crop which is of vital importance for farmers in semi-arid tropical regions, was evaluated in a 12 × 12 line × tester cross involving six male sterile (A) lines from five systems of cytoplasmic-genic male sterility, namely two male sterile lines from system A1(MS81A1, MS8A1), and one each from A2(Pb313A2), A3(Pb402A3), A4(MS81A4) and A5(MS81A5), the six corresponding maintainer (B) lines 81B1, 8B1, Pb313B2, Pb402B3, 81B4and 81B5, and twelve restorer (R) lines, namely H90/4-5, H77/833-2, G73-107, CSSC46-2, 77/245, 78/711, 77/273, ICR 161, ISK48, 77/28-2, 77/180 and Raj 42. The 24 parents and 144 crosses were grown separately in contiguous blocks in a randomized block design with two replications in three treatments each in 2000 and 2001 at the Research Farm, Bajra Section, Department of Plant Breeding, CCS HAU, Hisar. The plot size was 2.5 m × 0.45 m with 10 cm intra-row spacing. The genotypes (A lines, B lines, R lines, A × R crosses, B × R crosses), sowing dates, years, year × sowing date and genotype × treatment interactions (direct and reciprocal) exhibited significant differences. The comparison of mean performance of the early-sown non-ratooned crop vs. ratooned (cut, regenerated) vs. late-sown unratooned crop treatments revealed that both the grain and dry fodder yields and the major yield-contributing characters exhibited little reduction in the ratoon crop, while the total tillers at maturity and the effective tillers increased in the ratoon crop in comparison to the direct-sown crop. Additional green fodder yields of 189.63 g and 144.02 g per plant, harvested 40 days after sowing (DAS) in the ratoon crops in 2000 and 2001, respectively, and similar grain and dry fodder yields emphasized the utility of cutting and regeneration in pearl millet. The ratooning ability of genotypes, assessed from the ratio of the performance of various characters in ratoon and early and late sown unratooned crops for yield and major yield components was high for a number of lines, testers and hybrids. Most of the hybrids involved one or two parents with good regeneration potential. Sufficient genetic variability was observed for regeneration and ratooning ability, which was found to be under genetic control, suggesting that regeneration potential could be incorporated in genotypes with high yield. A base population developed from promising parents and crosses can be improved by cyclic breeding.
Effect of salicylic acid on growth and enzyme activities of wheat seedlings
Authors: Hayat S. , Fariduddin Q. , Ali B. , Ahmad A.
Published: January 2006

grains of wheat (Triticum aestivumL. cv. Raj-3077) were soaked in 0, 10-5, 10-4or 10-3 M aqueous solutions of salicylic acid (SA) for 3, 6 or 9 h. The seedlings raised from grains pre-treated with 10-5 M SA possessed significantly higher leaf number, fresh and dry mass per plant, and nitrate reductase and carbonic anhydrase activities 30 and 40 days after sowing. However, 10-3 M SA reduced all the above-mentioned parameters.
Development of a computed tomographic calibration method for the determination of lean meat content in pig carcasses
Authors: Romvári R. , Dobrowolski A. , Repa I. , Allen P. , Olsen E. , Szabó A. , Horn P.
Published: January 2006

Sixty left sides of pig carcasses were scanned by spiral computed tomography (CT) to measure lean meat weight and percentage. The carcasses were fully dissected and scanned to develop a calibration protocol. Different image analyses were performed on the basis of anatomically defined scans, direct volumetric estimation, body- and grey-scale ranges and using Partial Least Squares (PLS) regression of data provided by CT. The R2values of the calibrations for lean meat weight were 0.874, 0.976, 0.983 and 0.992, respectively, depending on the method applied. The PLS proved to be the best approach with a calibration RSD of 232 g. When changing from lean meat weight to percentage, the statistical goodness drops to a very small extent (R2= 0.988, RSD = 0.56). According to the results, the CT method can be recommended as a reference for determining the lean meat content of pig carcasses.
Effect of open pulled straw (ops) vitrification on the fertilisation rate and developmental competence of porcine oocytes
Authors: Varga Erika , Gardón J. C. , Bali Papp Ágnes
Published: January 2006

Freezing technologies are very important to preserve gametes and embryos of animals with a good pedigree or those having high genetic value. The aim of this work was to compare immature andin vitromatured porcine oocytes regarding their morphology and ability to be fertilised after vitrification by the open pulled straw (OPS) method. In four experiments 830 oocytes were examined. To investigate the effect of cumulus cells on oocyte survival after OPS vitrification, both denuded and cumulus-enclosed oocytes were vitrified at the germinal vesicle (GV) stage, then after vitrification they were maturedin vitro. Besides,in vitromatured oocytes surrounded with a cumulus and those without a cumulus were also vitrified. The survival of oocytes was evaluated by their morphology. Afterin vitrofertilisation the rates of oocytes penetrated by spermatozoa were compared. Our results suggest that the vitrification/warming procedure is the most effective in cumulus-enclosed oocytes (22.35 ± 1.75%). There was no difference between the order of maturation and vitrification in cumulus-enclosed oocytes, which suggests the importance of cumulus cells in protecting the viability of oocytes during cryopreservation.