Nucleus accumbens long-term depression and the expression of behavioral sensitization

Drug-dependent neural plasticity related to drug addiction and schizophrenia can be modeled in animals as behavioral sensitization, which is induced by repeated noncontingent or self-administration of many drugs of abuse. Molecular mechanisms that are critical for behavioral sensitization have yet to be specified. Long-term depression (LTD) of alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptor (AMPAR)-mediated synaptic transmission in the brain has been proposed as a cellular substrate for learning and memory. The expression of LTD in the nucleus accumbens (NAc) required clathrin-dependent endocytosis of postsynaptic AMPARs. NAc LTD was blocked by a dynamin-derived peptide that inhibited clathrin-mediated endocytosis or by a GluR2-derived peptide that blocked regulated AMPAR endocytosis. Systemic or intra-NAc infusion of the membrane-permeable GluR2 peptide prevented the expression of amphetamine-induced behavioral sensitization in the rat.     

Evoked potential correlates of auditory signal detection

A long-latency comnponent of the averaged evoked potential recorded from the human scalp varied in close relationship with subjects' perceptual reports in an auditory signal detection task. Detected signals evoked potentials several times larger than did undetected signals, falsely reported signals, or correctly reported nonsignals. The threshold signal intensity at which detection perfornmance exceeded chance levels was identical with concurrently obtained electro-physiological measures of threshold.     

Sprouting seed potatoes in low cost structures

Summary Over a period of three years seed potatoes were sprouted in three different types of container in three different structures. In a polythene-covered structure the effect of the container on sprout length was inconclusive but in a ventilated house the sprouts on seed in the trays and sacks were significantly longer than those in the boxes. In both structures the difference in the yields of the seed from the different container was not significant. The sprouts on the seed in the polythene-covered structure were longer and more numerous than those in the ventilated house, and although in one year the yield from seed from the polythene structure was significantly greater than that from the ventilated house in the following year this result was reversed. The seed from an open-fronted straw barn had the shortest sprouts and lowest yields.

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Zusammenfassung W?hrend einer dreij?hrigen Versuchsperiode wurde in Vorkeimkistchen, S?cken und Kisten eingelegtes Pflanzgut in einem belüfteten Kartoffellagerraum, in einer offenen Scheune und in einem im Freien aufgestellten Stapel vorgekeimt. Der Stapel war mit einer Poly?thylenfolie bedeckt und mittels eines elektrischen Heizkabels erw?rmt (Abb. 1; Tabelle 1). Man sch?tzte, dass für die Herrichtung des Stapels 70 Minuten (AK) pro Tonne Kartoffeln n?tig waren (Abb. 2; Tabelle 2). W?hrend der Lagerzeit wurde die Temperatur in den Vorkeimeinrichtungen registriert. Wenn diese 5 °C überschritt, wurde die Differenz (°C) mit der Zeit (Stunden) multipliziert und das Ergebnis als ‘Grad-Tage’ ausgedrückt (Tabelle 3). Vor dem Auspflanzen wurden Proben von den drei Varianten in den verschiedenen Vorkeimeinrichtungen genommen, um Daten über Keimzahl und Keiml?nge zu sammeln (Tabelle 4a) und Signifikanzwerte zu errechnen (Tabelle 4b). Im Fall der Vorkeimung unter Folie war die Auswirkung des Pflanzgutbeh?lters auf die Keiml?nge nicht entscheidend. Im belüfteten Kartoffellagerraum aber waren die Keime des Pflanzgutes aus den Vorkeimkisten und den S?cken bedeutend l?nger als solche aus den Kisten. In beiden F?llen zeigten die Ertr?ge des Pflanzgutes aus den verschiedenen Beh?ltern keine signifikanten Unterschiede (Tabellen 4a und 4b). Im allgemeinen wuchsen die Keime des unter der Poly?thylenfolie gelagerten Pflanzgutes l?nger als solche im belüfteten Lagerraum (Tabelle 4a); in einem Jahr brachte jenes Pflanzgut h?here Ertr?ge als dieses und im folgenden Jahr war es umgekehrt. Das Pflanzgut aus der offenen Scheune wies die kürzesten Keime und die kleinsten Ertr?ge auf. Aus den Resultaten ergeben sich die Folgerungen, dass der Vorkeimbeh?lter keinen Einfluss auf die Ertr?ge ausübt und dass es m?glich ist, den Mittelwert der l?ngsten Keime auf ungef?hr 12 mm zu beschr?nken. Ferner wurde festgestellt, dass eine Sonderausführung des Vorkeimhauses mit mechanischer Belüftung keinen deutlichen Vorteil bringt.

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Résumé Pendant trois années, on a fait germer des plants de pomme de terre conservés en caisses, en sacs et en caissettes dans trois types d'abri, soit dans un magasin ventilé, un hangar à c?tés ouverts et un système où les contenants étaient entassés en plein air, puis couverts d'un film de polyéthylène et chauffés électriquement par un cable flexible (Fig. 1, Tabl. 1). On a calculé que le temps nécessaire pour réaliser le troisième type d'abri était de 70 minutes de main d'oeuvre par tonne de pommes de terre stockées (Fig. 2, Tabl. 2). Pendant la période de stockage, on a enregistré la température dans les abris et on a calculé des ‘degré-jours’ (Tabl. 3) en multipliant le nombre de degrés audessus de 5 °C par le temps de dépassement (en heures). Avant la plantation, on a prélevé des échantillons dans les contenants dans chacun des trois abris, l'on a déterminé la longueur et le nombre de germes et l'on a calculé la signification des résultats (Tabl. 4b). L'influence du contenant sur la longueur des germes n'était pas concluante dans le cas d'abri en film de polyéthylène; par contre dans le magasin ventilé, les germes des tubercules étaient nettement plus longs dans les caisses et les sacs que dans les clayettes. Dans les deux cas, le contenant n'exer?ait pas d'influence significative sur la récolte (Tabl. 4a et 4b). En général, les germes des tubercules provenant de l'abri couvert de polyéthylène étaient plus longs et plus nombreux que ceux des échantillons provenant du magasin ventilé (Tabl. 4a). Une année, la récolte provenant des tubercules stockés dans le magasin ventilé a été supérieure, mais l'année suivante on observait le contraire. Les tubercules conservés dans le hangar à c?tes ouverts ont présenté les germes les plus courts et ont produit les rendements les plus bas. De tout quoi, il est conclu que le type de contenant dans lequel les germes se développent n'a pas d'influence sur la récolte et qu'il est possible de limiter la longueur moyenne des germes les plus longs à 12 mm environ. De plus, l'emploi d'un local spécial équipé d'un système mécanique de ventilation n'apporte aucun avantage pour la germination des plants de pomme de terre.

     

Geographical information systems-based models for offshore floating marine fish cage aquaculture site selection in Tenerife, Canary Islands

The present study focuses on the development of a standard methodology for selection of suitable sites for offshore (exposed) marine fish‐cage farming (floating cages) of seabream (Sparus aurata) and seabass (Dicentrarchus labrax) in an island environment, using Tenerife as an example. Site selection is a key factor in any aquaculture operation, affecting both success and sustainability and can solve conflicts between different activities, making a rational use of the coastal space. Site selection was achieved by using geographical information systems (GIS)‐based models and related technology to support the decision‐making process. The framework for spatial multicriteria decision analysis used in this study began with a recognition and definition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identified, defined and subdivided into eight submodels. These were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was verified by field sampling to establish the quality of data used. The decision maker's preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were incorporated using multicriteria evaluation techniques and simple overlays to provide an overall assessment of possible alternatives. The integration, manipulation and presentation of the results by means of GIS‐based models in this sequential and logical flow of steps proved to be very effective for helping the decision‐making process of site selection. Tenerife has very favourable environmental conditions for culture of marine fish and there are no totally unsuitable sites for cage farming identified in this study. On the other hand, there are few very suitable sites (high scores) either, principally due to the heavy use of the coastline and the conflicts between different users. From the 228 km² of available area for siting cages in the coastal regions with depth less than 50 m, the total area suitable for siting cages (scores 6–8) was 37 km². There are only 0.51 km² of very suitable areas (score 8) and approximately 5.37 km² of suitable (score 7), most of these being located in the southeast of the island. These relatively small areas of suitability should be put into the context of the wider use of the coastal environment around Tenerife.     

Experimental Eimeria debliecki infections in nursing and weaned pigs

Three litters of six, 3-day-old nursing pigs were inoculated via a stomach tube with 8.0 X 10(5), 1.6 X 10(6) or 5.0 X 10(6) sporulated oocysts of Eimeria debliecki and four groups of six, 4-week-old weaned pigs were inoculated with 8.0 X 10(5), 1.6 X 10(6), 5.0 X 10(6) or 1.0 X 10(7) sporulated oocysts of E. debliecki to determine its pathogenicity. Clinical coccidiosis or deaths did not result from infections. Infections were confined to the jejunum and occasionally the duodenum. Microscopic lesions of mild to moderate villous atrophy were observed in one nursing pig given 5.0 X 10(6) oocysts and three weaned pigs given 1.6 X 10(6), 5.0 X 10(6) and 1.0 X 10(7) oocysts and examined 5 days post-inoculation. Pathogenic bacteria or viruses were not demonstrated in any pigs. Results of this study indicate that E. debliecki is not a cause of neonatal or weaning diarrhea in pigs.     

Depolymerization of the Glutenin Macropolymer During Mixing: II. Differences in Retention of Specific Glutenin Subunits

The depolymerization of individual high and low molecular weight (HMW and LMW, respectively) glutenin subunits (GS) from the glutenin macropolymer (GMP) in doughs during mixing was investigated by reversed-phase (RP) HPLC and SDS-PAGE. Cultivars with different dough strengths, as well as lines null for specific HMW-GS and biotypes differing at individual HMW-GS and LMW-GS encoding loci, were studied. During mixing, the proportion of total HMW-GS in GMP decreased, and the ratios of different subunits in the GMP in doughs changed. There was a loss of chromosome 1B- and 1D-encoded x-HMW-GS, while the relative proportions of y-HMW-GS (among HMW-GS) increased. Changes in 1B subunits occurred first, while most of the changes in 1D HMW-GS content occurred during dough breakdown. Changes were more pronounced for doughs of weak to average strengths than for stronger doughs. RP-HPLC analysis demonstrated a consistent increase in the retention times (surface hydrophobicity) of chromosome 1D-encoded HMW-GS but not of other HMW-GS or LMW-GS during mixing. SDS-PAGE and RP-HPLC demonstrated that specific B subunits, typically those with lower hydrophobicity, were selectively depolymerized from the GMP during dough breakdown, while the proportions of specific C subunits, typically those with greater hydrophobicity, increased. Similar trends were seen in analyses of several pairs of biotypes differing at single LMW-GS encoding loci, although there were slight differences in the depolymerization behavior of wheats with different allelic compositions. The results suggest that dough breakdown may be triggered by the loss of specific HMW-GS from the GMP, and a structural hierarchy may exist for different LMW-GS within glutenin in doughs.     

A survey of contaminated ground with illustrative case histories

Contaminated ground represents a problem in all the industrialized countries of the world. Contaminated ground may give rise to hazards and that implies a degree of risk which also involves a problem of definition. The investigation of a site which is suspected of being contaminated differs somewhat from a routine site investigation. Sampling of soils, groundwater and gas producing material may be required. Various precautions may be necessary in doing this and operatives may have to wear protective clothing. The first case history considered involves a site investigation for a relief sewer in Glasgow, Scotland. As the site investigation progressed it ran into made‐ground which contained chemical waste. The presence of this waste meant that the nature of the investigation changed and much more stringent safety precautions had to be taken. It also meant that the initial location of the sewer tunnel had to be repositioned at greater depth in uncontaminated sandstone rather than in the superficial deposits above. Two further case histories associated with coal mining in the Ruhr district of Germany are included. The methods involved in investigating these two sites are described, as is their rehabilitation. Copyright © 2000 John Wiley & Sons, Ltd.