bluuebunny/crossref_metadata_2025_split huggingface dataset:
Within‐plant signalling via volatiles overcomes vascular constraints on systemic signalling and primes responses against herbivores
Authors: Frost Christopher J. , Appel Heidi M. , Carlson John E. , De Moraes Consuelo M. , Mescher Mark C. , Schultz Jack C. 
Published: May 2007

AbstractPlant volatiles play important roles in signalling between plants and insects, but their role in communication among plants remains controversial. Previous research on plant–plant communication has focused on interactions between neighbouring plants, largely overlooking the possibility that volatiles function as signals within plants. Here, we show that volatiles released by herbivore‐wounded leaves of hybrid poplar (Populus deltoides × nigra) prime defences in adjacent leaves with little or no vascular connection to the wounded leaves. Undamaged leaves exposed to volatiles from wounded leaves on the same stem had elevated defensive responses to feeding by gypsy moth larvae (Lymantria dispar L.) compared with leaves that did not receive volatiles. Volatile signals may facilitate systemic responses to localized herbivory even when the transmission of internal signals is constrained by vascular connectivity. Self‐signalling via volatiles is consistent with the short distances over which plant response to airborne cues has been observed to occur and has apparent benefits for emitting plants, suggesting that within‐plant signalling may have equal or greater ecological significance than signalling between plants.
Basin‐scale distribution patterns of picocyanobacterial lineages in the Atlantic Ocean
Authors: Zwirglmaier Katrin , Heywood Jane L. , Chamberlain Katie , Woodward E. Malcolm S. , Zubkov Mikhail V. , Scanlan Dave J. 
Published: May 2007

SummaryMarine picocyanobacteria of the genera Prochlorococcus and Synechococcus are major contributors to oceanic primary production. The genera are genetically diverse, comprising several known ecotypes or lineages. However, little is known of the distribution of these lineages over large geographic areas. Here, we analysed the relative abundance of Prochlorococcus ecotypes and Synechococcus lineages at the ocean basin scale along an Atlantic Meridional Transect (AMT) using dot blot hybridization and fluorescence in situ hybridization (FISH) techniques. The transect covered several contrasting oceanic provinces (gyres, upwelling, temperate regions) as well as environmentally ‘equivalent’ regions in the northern and southern hemisphere (northern and southern gyres and temperate regions). Flow cytometric data revealed a discrete separation in abundance of major picocyanobacterial genera. Prochlorococcus reached highest abundance in oligotrophic regions, while more mesotrophic waters were dominated by Synechococcus. Individual genetic lineages of both Prochlorococcus and Synechococcus showed highly similar distributions in corresponding regions in the northern and southern hemisphere. In addition, Prochlorococcus showed a distinctive depth distribution, with HLI and HLII ecotypes near the surface and co‐occurring LL ecotypes further down in the water column. Conversely, Synechococcus generally revealed no obvious depth preference, but did show highly specific distribution at the horizontal scale, with clades I and IV particularly dominating temperate, mesotrophic waters in both the northern and southern hemispheres. The data clearly reveal that specific picocyanobacterial lineages proliferate in similar oceanic provinces separated by large spatial scales. Furthermore, comparison with an earlier AMT dataset suggests that basin scale distribution patterns for Prochlorococcus ecotypes are remarkably reproducible from year to year.
Flow cytometric identification and enumeration of photosynthetic sulfur bacteria and potential for ecophysiological studies at the single‐cell level
Authors: Casamayor Emilio O. , Ferrera Isabel , Cristina Xavier , Borrego Carles M. , Gasol Josep M. 
Published: May 2007

SummaryWe show the potential of flow cytometry as a fast tool for population identification and enumeration of photosynthetic sulfur bacteria. Purple (PSB) and green sulfur bacteria (GSB) oxidize hydrogen sulfide to elemental sulfur that can act as storage compound to be further oxidized to sulfate generating the reducing power required for growth. Both groups have different elemental sulfur allocation strategies: whereas PSB store elemental sulfur as intracellular inclusions, GSB allocate sulfur globules externally. We used well‐characterized laboratory strains and complex natural photosynthetic populations developing in a sharply stratified meromictic lake to show that PSB and GSB could be detected, differentiated and enumerated in unstained samples using a blue laser‐based flow cytometer. Variations in cell‐specific pigment content and the dynamics of sulfur accumulation, both intra‐ and extracellularly, were also detected in flow cytometric plots as sulfur accumulation changed the light scatter characteristics of the cells. These data were used to show the potential for studies on the metabolic status and the rate of activity at the single‐cell level. Flow cytometric identification and enumeration resulted in faster and more precise analyses than previous approaches, and may open the door to more complex ecophysiological experiments with photosynthetic sulfur bacteria in mixed cultures and natural environments.
Coupling the GAL4 UAS system with alcR for versatile cell type‐specific chemically inducible gene expression in Arabidopsis
Authors: Sakvarelidze Lali , Tao Zheng , Bush Max , Roberts Gethin R. , Leader David J. , Doonan John H. , Rawsthorne Stephen 
Published: May 2007

SummaryThe Aspergillus alc regulon encodes a transcription factor, ALCR, which regulates transcription from cognate promoters such as alcA(p). In the presence of suitable chemical inducers, ALCR activates gene expression from alcA(p). The alc regulon can be transferred to other species and can be used to control the expression of reporter, metabolic and developmental genes in response to low‐level ethanol exposure. In this paper, we describe a versatile system for targeting the alc regulon to specific cell types in Arabidopsis by driving ALCR expression from the GAL4 upstream activator sequence (UAS). Large numbers of Arabidopsis lines are available in which GAL4 is expressed in a variety of spatial patterns and, in turn, drives the expression of any gene cloned downstream of the UAS. We have used a previously characterized line that directs gene expression to the endosperm to demonstrate spatially restricted ethanol‐inducible gene expression. We also show that the domain of inducible gene expression can easily be altered by crossing the UAS::ALCR cassette into different driver lines. We conclude that this gene switch can be used to drive gene expression in a highly responsive, but spatially restricted, manner.
Domestic Violence, Emotional Competence, and Child Adjustment
Authors: Katz Lynn Fainsilber , Hessler Danielle M. , Annest Amalia 
Published: May 2007

AbstractThis article examined emotion competence in children exposed to domestic violence (DV). It also examined the hypothesis that children's emotional competence mediates relations between DV and children's later difficulties with peers and behavioral adjustment. DV was assessed when children were at the age of five, emotional competence was assessed at the age of 9.5, and peer quality and behavioral adjustment were obtained at the age of 11. Children from homes with greater DV were less aware of their own emotions and more emotionally dysregulated at the age of 9.5. Emotional awareness mediated the relationship between DV at the age of five and children's friendship closeness and internalizing problems at the age of 11. Emotion dysregulation mediated the relationship between DV at the age of five and children's negative peer group interactions, social problems, and internalizing and externalizing problems at the age of 11. Results are discussed in terms of the impact of DV on children's emotional development and the role that different aspects of emotional competence play in children's socio‐emotional adjustment.
Children's Differentiation Between Ingratiation and Self‐Promotion
Authors: Watling Dawn , Banerjee Robin 
Published: May 2007

AbstractPrevious research has demonstrated that 10‐year‐olds can provide interpersonal explanations for certain self‐presentational tactics, but detailed information about the development of their understanding of these tactics is lacking. This research investigated children's understanding of the processes involved in ingratiation (used to indicate likeability) and self‐promotion (used to indicate competence). In the first study, with a sample of 60 children aged six to 11 years, children saw ingratiation as leading to more positive social evaluation than self‐promotion, which was seen as having a more concrete, instrumental function. Additionally, children's differentiation between ingratiation and self‐promotion was correlated with their level of peer preference, as determined through sociometric nominations, particularly for boys. In a second study, with a sample of 63 children aged six to 11 years, it was found that audience type (peer vs. adult) was related to children's understanding of the self‐presentational tactics: children offered more social evaluation justifications for a self‐promotion tactic when the audience was a peer rather than an adult. Results are discussed with reference to emerging insights into the links between peer relations and social cognition.
Sphingolipids are necessary for nicotinic acetylcholine receptor export in the early secretory pathway
Authors: Baier C. J. , Barrantes F. J. 
Published: May 2007

AbstractThe nicotinic acetylcholine receptor (AChR) is the prototype ligand‐gated ion channel, and its function is dependent on its lipid environment. In order to study the involvement of sphingolipids (SL) in AChR trafficking, we used pharmacological approaches to dissect the SL biosynthetic pathway in CHO‐K1/A5 cells heterologously expressing the muscle‐type AChR. When SL biosynthesis was impaired, the cell surface targeting of AChR diminished with a concomitant increase in the intracellular receptor pool. The SL‐inhibiting drugs increased unassembled AChR forms, which were retained at the endoplasmic reticulum (ER). These effects on AChR biogenesis and trafficking could be reversed by the addition of exogenous SL, such as sphingomyelin. On the basis of these effects we propose a ‘chaperone‐like’ SL intervention at early stages of the AChR biosynthetic pathway, affecting both the efficiency of the assembly process and subsequent receptor trafficking to the cell surface.
Dopamine depletion and subsequent treatment with l‐DOPA, but not the long‐lived dopamine agonist pergolide, enhances activity of the Akt pathway in the rat striatum
Authors: Bychkov Evgeny , Ahmed M. Rafiuddin , Dalby Kevin N. , Gurevich Eugenia V. 
Published: May 2007

AbstractDysregulation of signaling pathways is believed to contribute to Parkinson’s disease pathology and l‐DOPA‐induced motor complications. Long‐lived dopamine (DA) agonists are less likely to cause motor complications by virtue of continuous stimulation of DA receptors. In this study, we compared the effects of the unilateral 6‐hydroxydopamine lesion and subsequent treatment with l‐DOPA and DA agonist pergolide on signaling pathways in rats. Pergolide caused less pronounced behavioral sensitization than l‐DOPA (25 mg/kg, i.p., 10 days), particularly at lower dose (0.5 and 0.25 mg/kg, i.p.). Pergolide, but not l‐DOPA, reversed lesion‐induced up‐regulation of preproenkephalin and did not up‐regulate preprodynorphine or DA D3 receptor in the lesioned hemisphere. Pergolide was as effective as l‐DOPA in reversing the lesion‐induced elevation of ERK2 phosphorylation in response to acute apomorphine administration (0.05 mg/kg, s.c.). Chronic l‐DOPA significantly elevated the level of Akt phosphorylation at both Thr308 and Ser473 and concentration of phosphorylated GSK3α, whereas pergolide suppressed the lesion‐ and/or challenge‐induced supersensitive Akt responses. The data indicate that l‐DOPA, unlike pergolide, exacerbates imbalances in the Akt pathway caused by the loss of DA. The results support the hypothesis that the Akt pathway is involved in long‐term actions of l‐DOPA and may be linked to l‐DOPA‐induced dyskinesia.
Copper induced oxidation of serotonin: analysis of products and toxicity
Authors: Jones Christopher E. , Underwood Clare K. , Coulson Elizabeth J. , Taylor Paul J. 
Published: May 2007

AbstractSerotonin is a major neurotransmitter that controls many functions, ranging from mood and behaviour through to sleep and motor functions. The non‐enzymatic oxidation of serotonin is of significant importance as some oxidation products are considered to be neurotoxic. An interaction between copper and serotonin has been suggested by symptoms observed in a number of neurodegenerative diseases such as Wilson’s and Prion diseases. Using PC12 cells as a model of neuronal cells, we show that the interaction between copper and serotonin is toxic to undifferentiated cells. The toxicity is largely due to reactive oxygen species as cell death is significantly reduced in the presence of the antioxidant mannitol. Differentiation of the PC12 cells also confers resistance to the oxidative process. In vitro oxidation of serotonin by copper results in the eventual formation of a coloured pigment, thought to be a melanin‐like polymeric species. Using spectroscopic methods we provide evidence for the formation of a single intermediate product. This dimeric intermediate was identified and characterized as 5,5′‐dihydroxy‐4,4′‐bitryptamine. These results indicate that copper structurally alters serotonin and this process may play a role in copper related neurodegenerative diseases.
Genetically augmenting tau levels does not modulate the onset or progression of Aβ pathology in transgenic mice
Authors: Oddo Salvatore , Caccamo Antonella , Cheng David , Jouleh Bahareh , Torp Reidun , LaFerla Frank M. 
Published: May 2007

AbstractThe two hallmark pathologies of Alzheimer’s disease (AD) are amyloid plaques, composed of the small amyloid‐β (Aβ) peptide, and neurofibrillary tangles, comprised aggregates of the microtubule binding protein, tau. The molecular linkage between these two lesions, however, remains unknown. Based on human and mouse studies, it is clear that the development of Aβ pathology can trigger tau pathology, either directly or indirectly. However, it remains to be established if the interaction between Aβ and tau is bidirectional and whether the modulation of tau will influence Aβ pathology. To address this question, we used the 3xTg‐AD mouse model, which is characterized by the age‐dependent buildup of both plaques and tangles. Here we show that genetically augmenting tau levels and hyperphosphorylation in the 3xTg‐AD mice has no effect on the onset and progression of Aβ pathology. These data suggest that the link between Aβ and tau is predominantly if not exclusively unidirectional, which is consistent with the Aβ cascade hypothesis and may explain why tauopathy‐only disorders are devoid of any Aβ pathology.
Increased stem cell proliferation in the spinal cord of adult amyotrophic lateral sclerosis transgenic mice
Authors: Guan Ying‐jun , Wang Xin , Wang Hong‐yan , Kawagishi Kyutaro , Ryu Hoon , Huo Chun‐feng , Shimony Ethan M. , Kristal Bruce S. , Kuhn Hans‐Georg , Friedlander Robert M. 
Published: May 2007

AbstractHarnessing the regenerative potential of the central nervous system to repopulate depleted cellular populations from endogenous stem cells would be a novel approach for the treatment of neurological diseases resulting from cell death. Consequently, understanding if and how the central nervous system is capable of such regeneration would determine if such an approach is feasible. In this report, we provide evidence of widespread regenerative response in the spinal cord of amyotrophic lateral sclerosis transgenic mice. However, this regenerative response appears to be largely unproductive. We demonstrate that there is significantly increased gliogenesis, but an absence of convincing neurogenesis. The fact that the neurodegenerative process stimulates a regenerative response suggests that the adult spinal cord has at least limited ability for regeneration. Further studies will determine if this endogenous regenerative process can be enhanced and directed so as to slow or even reverse the natural progression of this devastating disease.
Aggregation of cellular prion protein is initiated by proximity‐induced dimerization
Authors: Goggin Kevin , Bissonnette Cyntia , Grenier Catherine , Volkov Leonid , Roucou Xavier 
Published: May 2007

AbstractPrion diseases or transmissible spongiform encephalopathies (TSEs) are infectious and fatal neurodegenerative disorders in humans and animals. Pathological features of TSEs include the conversion of cellular prion protein (PrPC) into an altered disease‐associated conformation generally designated PrPSc, abnormal deposition of PrPSc aggregates, and spongiform degeneration of the brain. The molecular steps leading to PrPC aggregation are unknown. Here, we have utilized an inducible oligomerization strategy to test if, in the absence of any infectious prion particles, the encounter between PrPC molecules may trigger its aggregation in neuronal cells. A chimeric PrPC composed of one (Fv1) or two (Fv2) modified FK506‐binding protein (Fv) fused with PrPC were created, and transfected in N2a cells. Similar to PrPC, Fv1‐PrP and Fv2‐PrP were glycosylated, displayed normal localization, and anti‐apoptotic function. When cells were treated with the dimeric Fv ligand AP20187, to induce dimerization (Fv1) or oligomerization (Fv2) of PrPC, both dimerization and oligomerization of PrPC resulted in the de novo production, release and deposition of extracellular PrP aggregates. Aggregates were insoluble in non‐ionic detergents and partially resistant to proteinase K. These findings demonstrate that homologous interactions between PrPC molecules may constitute a minimal and sufficient molecular event leading to PrPC aggregation and extracellular deposition.
Elevated plasma cholesterol does not affect brain Aβ in mice lacking the low‐density lipoprotein receptor
Authors: Elder Gregory A. , Cho Julie Y. , English Daniel F. , Franciosi Sonia , Schmeidler James , Sosa Miguel A. Gama , Gasperi Rita De , Fisher Edward A. , Mathews Paul M. , Haroutunian Vahram , Buxbaum Joseph D. 
Published: May 2007

AbstractEpidemiological studies support an association between vascular risk factors, including hypercholesterolemia, and Alzheimer’s disease (AD). Recently, there has been much interest in the possibility that hypercholesterolemia might directly promote β‐amyloid (Aβ) production. Indeed, in vitro studies have shown that increasing cellular cholesterol levels enhances Aβ production. However, studies in AD transgenic mouse models have not consistently found that elevated plasma cholesterol leads to increased Aβ production or deposition in vivo. In this study, we determined whether elevated peripheral cholesterol influences Aβ production in mice with a null mutation of the low‐density lipoprotein receptor (LDLR). We show that dramatically elevated plasma cholesterol levels, whether induced by high cholesterol, high fat, or high fat/high cholesterol diets, did not affect either levels of brain Aβ40, Aβ42, or APP, or the Aβ42/40 or APP‐CTF/APP ratios, nor substantially alter brain cholesterol levels. ApoE protein levels in brain were, however, elevated, in LDLR−/− mice by post‐transcriptional mechanisms. Collectively, these studies argue that plasma cholesterol levels do not normally regulate production of brain Aβ.
The organotellurium compound ammonium trichloro(dioxoethylene‐0,0′) tellurate enhances neuronal survival and improves functional outcome in an ischemic stroke model in mice
Authors: Okun Eitan , Arumugam Thiruma V. , Tang Sung‐Chun , Gleichmann Marc , Albeck Michael , Sredni Benjamin , Mattson Mark P. 
Published: May 2007

AbstractAmmonium trichloro(dioxoethylene‐0,0′) tellurate (AS101) is a non‐toxic organotellurium compound with pleiotropic activities. It was recently shown to induce production of the neurotrophic factor glial cell line‐derived neurotrophic factor and to rescue neuronal‐like PC‐12 cells from neurotrophic factor deprivation‐induced apoptosis. In this study, we show that AS101 improves functional outcome and reduces brain damage in a mouse model of focal ischemic stroke. Both pre‐stroke and post‐stroke intraperitoneal treatments with AS101 reduced infarct size and edema and improved the neurological function of the animals. AS101 treatments reduced both apoptotic and inflammatory caspase activities, and also inhibited protein tyrosine nitration suggesting that AS101 suppresses oxidative stress. Studies of cultured neurons showed that AS101 confers protection against apoptosis induced by either glucose deprivation or the lipid peroxidation product 4‐hydroxynonenal. Moreover, AS101 treatment reduced glutamate‐induced intracellular calcium elevation, a major contributor to neuronal death in stroke. As AS101 has an excellent safety profile in humans, our pre‐clinical data suggest a potential therapeutic benefit of AS101 in patients suffering from stroke and other neurodegenerative conditions.
A specific inhibitor of cholesterol biosynthesis, BM15.766, reduces the expression of β‐secretase and the production of amyloid‐βin vitro
Authors: Parsons Richard B. , Subramaniam Daryl , Austen Brian M. 
Published: May 2007

AbstractWe have previously shown that statins reduce the production of amyloid‐β (Aβ) by both isoprenoid‐ and cholesterol‐dependent mechanisms. These pathways contribute to the regulation of the dimerisation of BACE into its physiologically active form. Statins reduce cellular cholesterol levels by 20–40%; therefore, it is possible that the remaining cholesterol within the cell may play a significant role in the production of Aβ. Incubation of cells with the specific cholesterol biosynthesis inhibitor BM15.766 together with 50 μmol/L simvastatin and 400 μmol/L mevalonate reduced cellular cholesterol levels in a dose‐dependent manner with increasing BM15.766 concentration (r = −0.9736, p = 0.0264). Furthermore, decreases in cellular cholesterol levels correlated with reductions in total Aβ production (r = 0.9683, p = 0.0317). A total of 2.5 μmol/L BM15.766 inhibited the dimerisation of BACE, whilst the expression of BACE monomer was reduced by 5 μmol/L BM15.766. BM15.766 treatment localised BACE predominantly within the Golgi, and reduced total BACE expression per cell. Similar changes were observed in the expression of the Golgi marker golgin‐97, suggesting that reduced BACE expression may arise from a decrease in protein trafficking and an increase in degradation. By targeting cholesterol synthesis using specific cholesterol biosynthesis inhibitors, it is possible to reduce Aβ production without reducing protein isoprenylation.
Characterization of microsatellite loci in the endangered grand spider orchid Caladenia huegelii (Orchidaceae)
Authors: SWARTS NIGEL D. , SINCLAIR ELIZABETH A. , DIXON KINGSLEY W. 
Published: May 2007

AbstractThe orchid genus Caladenia is species rich with many threatened and endangered taxa. We report on the isolation and characterization of microsatellite loci in the rare Caladenia huegelii for molecular evaluation of this and the closely related C. thinicola as part of the development of conservation initiatives. Eight di‐ and trinucleotide loci were screened using 30 samples from each species. All loci were highly variable, with similar levels of heterozygosity and number of alleles across both species. These markers will be highly informative for population studies in both species.