bluuebunny/crossref_metadata_2025_split huggingface dataset:
α7‐Nicotinic acetylcholine receptors mediate an Aβ1−42‐induced increase in the level of acetylcholinesterase in primary cortical neurones
Authors: Fodero L. R. , Mok S. S. , Losic D. , Martin L. L. , Aguilar M. I. , Barrow C. J. , Livett B. G. , Small D. H. 
Published: February 2004

AbstractThe β‐amyloid protein (Aβ) is the major protein component of amyloid plaques found in the Alzheimer brain. Although there is a loss of acetylcholinesterase (AChE) from both cholinergic and non‐cholinergic neurones in the brain of Alzheimer patients, the level of AChE is increased around amyloid plaques. Previous studies using P19 cells in culture and transgenic mice which overexpress human Aβ have suggested that this increase may be due to a direct action of Aβ on AChE expression in cells adjacent to amyloid plaques. The aim of the present study was to examine the mechanism by which Aβ increases levels of AChE in primary cortical neurones. Aβ1−42 was more potent than Aβ1−40 in its ability to increase AChE in primary cortical neurones. The increase in AChE was unrelated to the toxic effects of the Aβ peptides. The effect of Aβ1−42 on AChE was blocked by inhibitors of α7 nicotinic acetylcholine receptors (α7 nAChRs) as well as by inhibitors of L‐ or N‐type voltage‐dependent calcium channels (VDCCs), whereas agonists of α7 nAChRs (choline, nicotine) increased the level of AChE. The results demonstrate that the effect of Aβ1−42 on AChE is due to an agonist effect of Aβ1−42 on the α7 nAChR.
Testosterone amplifies excitotoxic damage of cultured oligodendrocytes
Authors: Caruso A. , Di Giorgi Gerevini V. , Castiglione M. , Marinelli F. , Tomassini V. , Pozzilli C. , Caricasole A. , Bruno V. , Caciagli F. , Moretti A. , Nicoletti F. , Melchiorri D. 
Published: February 2004

AbstractAn overactivation of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA)/kainate receptors has been implicated in the pathophysiology of oligodendrocyte damage in demyelinating disorders of the CNS. We decided to examine the effect of testosterone on excitotoxic death of oligodendrocytes because a gender difference exists in the incidence and disease course of multiple sclerosis. Short‐term pure cultures of oligodendrocytes (4 days in vitro) were exposed to a brief pulse with kainate or AMPA + cyclothiazide for the induction of excitotoxicity. Exposure to testosterone enantate was slightly toxic per se and amplified both AMPA and kainate toxicity. Testosterone treatment induced all gene targets of p53, and amplified the induction of these genes induced by kainate. The effect of testosterone was mediated by the activation of androgen receptors and was resistant to the aromatase inhibitors, dl‐aminoglutethimide and 4‐hydroxyandrost‐4‐ene‐3,17‐dione. Testosterone treatment also potentiated the stimulation of 45Ca2+ influx induced by AMPA + cyclothiazide or kainate without changing the expression of the glutamate receptor (GluR) 1, ‐2/3, and ‐4 subunits of AMPA receptors or the GluR6/7 subunits of kainate receptors. We conclude that testosterone amplifies excitotoxic damage of oligodendrocytes acting at an early step of the death cascade triggered by AMPA/kainate receptors.
Genetic diversity and insecticide resistance of Myzus persicae (Hemiptera: Aphididae) populations from tobacco in Chile: evidence for the existence of a single predominant clone
Authors: Fuentes-Contreras E. , Figueroa C.C. , Reyes M. , Briones L.M. , Niemeyer H.M. 
Published: February 2004

AbstractThe tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M. nicotianae Blackman, was introduced into Chile during the last decade. In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey. The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis. Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene. All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M. persicae. Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.
A bioassay to evaluate the activity of chemical stimuli from grape berries on the oviposition of Lobesia botrana (Lepidoptera: Tortricidae)
Authors: Maher N. , Thiéry D. 
Published: February 2004

AbstractA two-choice bioassay was developed to evaluate the role of host-plant berry compounds on the oviposition site acceptance of the generalist moth Lobesia botrana (Denis & Shiffermüller). A key feature was the lining of the bioassay arena with felt which focused oviposition on the test substrates. Initial experiments comparing substrates with different physical features indicated that smooth textures and spherical shapes with interstices favour oviposition. Artificial oviposition substrates were thus constructed with glass spheres in order to test the behavioural activity of grapevine berry extracts. Only polar extracts obtained by soaking berries in methanol or water stimulated oviposition (more eggs were laid on the extract-treated substrate than on the control substrate), whereas more apolar ones obtained with chloroform or hexane had no significant effect. The prior removal of epicuticular waxes from grape berries before extraction did not enhance the stimulatory activity of the methanol extract. The oviposition response to this extract was dose-dependent. It is concluded that polar compounds present on grape berries act as oviposition stimulants for L. botrana.
Estimating population density of the Formosan subterranean termite, Coptotermes formosanus(Isoptera: Rhinotermitidae) using the effective sampling area of in-ground monitoring stations
Authors: Puche H. , Su N.-Y. 
Published: February 2004

AbstractThe effective sampling area of a monitoring station, α, was calculated for several Coptotermes formosanus Shiraki colonies in Broward County, Florida, USA. A simple mark–recapture protocol provided data on termite station catch within a foraging range of a colony. Average recapture probability was 0.005 close to the releae point (< 5 m) and declined to 0.0008 at a distance of 51 to 60 m. The relation between the log % termites recaptured was fitted with log distance, to determine P(x), the average proportion of captured termites that started at distance x from the release point. The effective sampling area was estimated by using P(x) and the equation, α 2 π∫{ x P(x)} dx. Integrating this equation, an average estimate α that ranged from 0.607 to 14.5 m2 was obtained. Factors influencing the variation of α among the colonies are discussed. The effective sampling area estimated should be taken as a reliable estimator that translates subterranean termite catches into termite population density.
Host plant age and population development of a cereal aphid, Metopolophium dirhodum (Hemiptera: Aphididae)
Authors: Honek A. , Martinkova Z. 
Published: February 2004

AbstractThe sudden decline following the peak in population abundance of aphids on crops of small grain cereals is attributed to the joint effect of natural enemies and plant senescence. To distinguish between these causes, a four year experiment was established in which the numbers of Metopolophium dirhodum (Walker) infesting spring wheat plots sown from April to June at c. 14 day intervals were determined. Aphid abundance in replicates sown at successive dates peaked within a period of 5–9 days (106–171 day degrees above a base temperature of 0°C) although their sowing dates varied by 62–97 days (727–1106 day degrees). At the time of the aphid population peaks, plants in the different sowings differed in age (11–99 days), developmental stage (stage 15–65 on the Zadoks scale), leaf nitrogen content and shoot mass. Maximum abundance of M. dirhodum decreased with sowing date because the time available for its population increase was shorter on late than early sowings. The abundance of M. dirhodum on spring wheat was similar to its abundance on winter wheat. After reaching peak abundance, aphids declined in numbers within 3–7 days. The effect of host plant ageing on the M. dirhodumdecline thus appeared small. Natural enemies (largely mycoses), and timing of alata production may have contributed to the aphid decline.
Role of modified CDC miniature light-traps as an alternative method for sampling adult anophelines (Diptera: Culicidae) in the National Mosquito Surveillance Programme in India
Authors: Sadanandane C. , Jambulingam P. , Subramanian S. 
Published: February 2004

AbstractThe efficiency of modified CDC miniature light-traps for sampling adult mosquitoes was evaluated in comparison with indoor resting, outdoor resting, indoor man-landing and outdoor man-landing collections in the hilly district of Koraput, Orissa, India. Overall, light-traps captured 78% of adult mosquitoes collected by all methods. Of the 16 anopheline species recorded in the study area, light-traps effectively sampled 13, contributing about 72% of the total anophelines collected by all methods. Light-traps also caught a large number of female Culex vishnui Theobald (96%). As fully-fed mosquitoes were predominant (82%) and caught alive, light-traps can be used to catch large numbers of vector mosquitoes for studies on vector prevalence, distribution, vector incrimination and also for laboratory bioassays. Light-trap and indoor resting collections revealed similar seasonal trends in numbers of Anopheles culicifacies Giles, A. fluviatilis James, A. jeyporiensis James, A. vagus Doenitz, and A. splendidus Koidzumi. Age-structure of the samples did not vary significantly between the two methods. Light-traps could be used as an alternative to daytime indoor resting collections to monitor the seasonal fluctuations in the abundance and parity rates of these species. The light-trap collections correlated with indoor and outdoor man-landing collections of A. jeyporiensis and the outdoor man-landing collections of A. maculatusTheobald in measuring seasonal trends. Light-trap collections can thus be used as a substitute for man-landing collections of A. jeyporiensis and A. maculatus.
Comparing mark–recapture and constant removal protocols for estimating forager population size of the subterranean termite Coptotermes lacteus (Isoptera: Rhinotermitidae)
Authors: Evans T.A. 
Published: February 2004

AbstractForager population sizes of colonies of Coptotermes lacteus(Froggatt) in New South Wales were estimated using two methods: mark–recapture and constant removal, in two disturbed habitats: a pine plantation and cleared farmland. Mark–recapture population estimates were unrealistic and unreliable: they could be improbably large, over 200 million foragers, and they varied enormously between samples for each colony without any pattern. The constant removal population estimates could also be unrealistic: they could be negative or quite different when calculated using regression and maximum likelihood methods. However, the unrealistic results could be predicted reliably, and explained by the lack of re-contact with the sampling devices (bait stations) – a violation of an assumption of the method. This happened more frequently in the plantation than in the farmland, probably because of the greater abundance of alternative food sources in the plantation. Of the two methods, constant removal provided reasonable forager population estimates, relative to direct counts, at least some of the time, plus a mechanism by which reliability could be tested, whereas mark–recapture provided neither. Further refinement and testing of constant removal methods are urged to provide a more reliable population estimation technique for termites.
Auxin from the Developing Inflorescence Is Required for the Biosynthesis of Active Gibberellins in Barley Stems
Authors: Wolbang Carla M. , Chandler Peter M. , Smith Jennifer J. , Ross John J. 
Published: February 2004

Abstract
Multiple gibberellins (GAs) were quantified in the stems of intact, decapitated, and decapitated auxin-treated barley (Hordeum vulgare) plants. Removal of the developing inflorescence reduced the endogenous levels of indole-3-acetic acid (IAA), GA1, and GA3 and increased the level of GA29 in internodal and nodal tissues below the site of excision. Application of IAA to the excised stump restored GA levels to normal in almost all cases. The conversion of [14C]GA20 to bioactive [14C]GA1 and of [14C]GA5 to bioactive [14C]GA3 was reduced by decapitation, and IAA application was able to restore conversion rates back to the levels found in intact plants. The amount of mRNA for the principal vegetative 3-oxidase (converting GA20 to GA1, and GA5 to GA3) was decreased in decapitated plants and restored by IAA application. The results indicate that the inflorescence of barley is a source of IAA that is transported basipetally into the internodes and nodes where bioactive GA1 and GA3 are biosynthesized. Thus, IAA is required for normal GA biosynthesis in stems, acting at multiple steps in the latter part of the pathway.
Hyperaccumulation of Cadmium and Zinc in Thlaspi caerulescens and Arabidopsis halleri at the Leaf Cellular Level
Authors: Cosio Claudia , Martinoia Enrico , Keller Catherine 
Published: February 2004

Abstract
Vacuolar compartmentalization or cell wall binding in leaves could play a major role in hyperaccumulation of heavy metals. However, little is known about the physiology of intracellular cadmium (Cd) sequestration in plants. We investigated the role of the leaf cells in allocating metal in hyperaccumulating plants by measuring short-term 109Cd and 65Zn uptake in mesophyll protoplasts of Thlaspi caerulescens “Ganges” and Arabidopsis halleri, both hyperaccumulators of zinc (Zn) and Cd, and T. caerulescens “Prayon,” accumulating Cd at a lower degree. The effects of low temperature, several divalent cations, and pre-exposure of the plants to metals were investigated. There was no significant difference between the Michaelis-Menten kinetic constants of the three plants. It indicates that differences in metal uptake cannot be explained by different constitutive transport capacities at the leaf protoplast level and that plasma and vacuole membranes of mesophyll cells are not responsible for the differences observed in heavy metal allocation. This suggests the existence of regulation mechanisms before the plasma membrane of leaf mesophyll protoplasts. However, pre-exposure of the plants to Cd induced an increase in Cd accumulation in protoplasts of “Ganges,” whereas it decreased Cd accumulation in A. halleri protoplasts, indicating that Cd-permeable transport proteins are differentially regulated. The experiment with competitors has shown that probably more than one single transport system is carrying Cd in parallel into the cell and that in T. caerulescens “Prayon,” Cd could be transported by a Zn and Ca pathway, whereas in “Ganges,” Cd could be transported mainly by other pathways.
Temporal Dynamics of Carbon Partitioning and Rhizodeposition in Wheat
Authors: Dilkes Nigel B. , Jones David L. , Farrar John 
Published: February 2004

Abstract
The temporal dynamics of partitioning and rhizodeposition of recent photosynthate in wheat (Triticum aestivum) roots were quantified in situ in solution culture. After a 30-min pulse of 14CO2 to a single intact leaf, 14C activities of individual carbon fluxes in the root, including exudation, respiration, and root content, were measured continuously over the next 20 h concurrently with 14C efflux from the leaf. Immediately after the end of the 14CO2 pulse, 14C activity was detected in the root, the hydroponic solution, and in root respiration. The rate of 14C exudation from the root was maximal after 2 to 3 h, and declined to one-third of maximum after a further 5 h. Completion of the rapid phase of 14C efflux from the leaf coincided with peak 14C exudation rate. Thus, exudation flux is much more rapidly and dynamically coupled to current photosynthesis than has been appreciated. Careful cross-calibration of 14C counting methods allowed a dynamic 14C budget to be constructed for the root. Cumulative 14C exudation after 20 h was around 3% of 14C fixed in photosynthesis. Partitioning of photosynthate between shoot and root was manipulated by partial defoliation before applying the 14CO2 pulse to the remaining intact leaf. Although the rate of photosynthesis was largely unaffected by partial defoliation, the proportion of new photosynthate subsequently partitioned to and exuded from the root was substantially reduced. This clearly indicates that exudation depends more on the rate of carbon import into the root than on the rate of photosynthesis.
Arabidopsis Type B Monogalactosyldiacylglycerol Synthase Genes Are Expressed during Pollen Tube Growth and Induced by Phosphate Starvation
Authors: Kobayashi Koichi , Awai Koichiro , Takamiya Ken-ichiro , Ohta Hiroyuki 
Published: February 2004

Abstract
The galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) constitute the major glycolipids of the thylakoid membranes in chloroplasts. In Arabidopsis, the formation of MGDG is catalyzed by a family of three MGDG synthases, which are encoded by two types of genes, namely type A (atMGD1) and type B (atMGD2 and atMGD3). Although the roles of the type A enzyme have been intensively investigated in several plants, little is known about the contribution of type B enzymes to MGDG synthesis in planta. From our previous analyses, unique expression profiles of the three MGDG synthase genes were revealed in various organs and developmental stages. To characterize the expression profiles in more detail, we performed histochemical analysis of these genes using β-glucuronidase (GUS) assays in Arabidopsis. The expression of atMGD1::GUS was detected highly in all green tissues, whereas the expression of atMGD2::GUS and atMGD3::GUS was observed only in restricted parts, such as leaf tips. In addition, intense staining was detected in pollen grains of all transformants. We also detected GUS activity in the pollen tubes of atMGD2::GUS and atMGD3::GUS transformants grown in wild-type stigmas but not in atMGD1::GUS, suggesting that type B MGDG synthases may have roles during pollen germination and pollen tube growth. GUS analysis also revealed that expression of atMGD2 and atMGD3, but not atMGD1, are strongly induced during phosphate starvation, particularly in roots. Because only DGDG accumulates in roots during phosphate deprivation, type B MGDG synthases may be acting primarily to supply MGDG as a precursor for DGDG synthesis.
PvUPS1, an Allantoin Transporter in Nodulated Roots of French Bean
Authors: Pélissier Hélène C. , Frerich Anke , Desimone Marcelo , Schumacher Karin , Tegeder Mechthild 
Published: February 2004

Abstract
Nodulated legumes receive their nitrogen via nitrogen-fixing rhizobia, which exist in a symbiotic relationship with the root system. In tropical legumes like French bean (Phaseolus vulgaris) or soybean (Glycine max), most of the fixed nitrogen is used for synthesis of the ureides allantoin and allantoic acid, the major long-distance transport forms of organic nitrogen in these species. The purpose of this investigation was to identify a ureide transporter that would allow us to further characterize the mechanisms regulating ureide partitioning in legume roots. A putative allantoin transporter (PvUPS1) was isolated from nodulated roots of French bean and was functionally characterized in an allantoin transport-deficient yeast mutant showing that PvUPS1 transports allantoin but also binds its precursors xanthine and uric acid. In beans, PvUPS1 was expressed throughout the plant body, with strongest expression in nodulated roots, source leaves, pods, and seed coats. In roots, PvUPS1 expression was dependent on the status of nodulation, with highest expression in nodules and roots of nodulated plants compared with non-nodulated roots supplied with ammonium nitrate or allantoin. In situ RNA hybridization localized PvUPS1 to the nodule endodermis and the endodermis and phloem of the nodule vasculature. These results strengthen our prediction that in bean nodules, PvUPS1 is involved in delivery of allantoin to the vascular bundle and loading into the nodule phloem.
Wounding Enhances Expression of AtSUC3, a Sucrose Transporter from Arabidopsis Sieve Elements and Sink Tissues
Authors: Meyer Stefan , Lauterbach Christian , Niedermeier Matthias , Barth Inga , Sjolund Richard D. , Sauer Norbert 
Published: February 2004

Abstract
The Arabidopsis AtSUC3 gene encodes a sucrose (Suc) transporter that differs in size and intron number from all other Arabidopsis Suc transport proteins. Each plant species analyzed so far possesses one transporter of this special type, and several functions have been discussed for these proteins, including the catalysis of transmembrane Suc transport, and also Suc sensing and regulation of other Suc transporters. Here, we show that the AtSUC3 protein is localized in the sieve elements of the Arabidopsis phloem and is not colocalized with the companion cell-specific AtSUC2 phloem loader. Even stronger AtSUC3 expression is observed in numerous sink cells and tissues, such as guard cells, trichomes, germinating pollen, root tips, the developing seed coat, or stipules. Moreover, AtSUC3 expression is strongly induced upon wounding of Arabidopsis tissue. The physiological role of AtSUC3 in these different cells and tissues is discussed.
Lipoic Acid-Dependent Oxidative Catabolism of α-Keto Acids in Mitochondria Provides Evidence for Branched-Chain Amino Acid Catabolism in Arabidopsis
Authors: Taylor Nicolas L. , Heazlewood Joshua L. , Day David A. , Millar A. Harvey 
Published: February 2004

Abstract
Lipoic acid-dependent pathways of α-keto acid oxidation by mitochondria were investigated in pea (Pisum sativum), rice (Oryza sativa), and Arabidopsis. Proteins containing covalently bound lipoic acid were identified on isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis separations of mitochondrial proteins by the use of antibodies raised to this cofactor. All these proteins were identified by tandem mass spectrometry. Lipoic acid-containing acyltransferases from pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex were identified from all three species. In addition, acyltransferases from the branched-chain dehydrogenase complex were identified in both Arabidopsis and rice mitochondria. The substrate-dependent reduction of NAD+ was analyzed by spectrophotometry using specific α-keto acids. Pyruvate- and α-ketoglutarate-dependent reactions were measured in all three species. Activity of the branched-chain dehydrogenase complex was only measurable in Arabidopsis mitochondria using substrates that represented the α-keto acids derived by deamination of branched-chain amino acids (Val [valine], leucine, and isoleucine). The rate of branched-chain amino acid- and α-keto acid-dependent oxygen consumption by intact Arabidopsis mitochondria was highest with Val and the Val-derived α-keto acid, α-ketoisovaleric acid. Sequencing of peptides derived from trypsination of Arabidopsis mitochondrial proteins revealed the presence of many of the enzymes required for the oxidation of all three branched-chain amino acids. The potential role of branched-chain amino acid catabolism as an oxidative phosphorylation energy source or as a detoxification pathway during plant stress is discussed.