Outer membrane protein profiles of Edwardsiella ictaluri from fish.

Outer membrane proteins (OMP) prepared with sodium N-lauroyl sarcocinate (SLS) from 33 Edwardsiella ictaluri isolates from fish were examined by electrophoresis. Twenty-eight isolates from channel catfish (Ictalurus punctatus) had similar OMP profiles. Ten bands (71 kilodaltons [kD] to 19.5 kD) were identified in all isolates from channel catfish. One major 35-kD protein comprised most of the protein content of the outer membrane of isolates from channel catfish. Differences existed among isolates in the amount of protein within minor OMP bands. Edwardsiella ictaluri ATCC 33202 contained larger quantities of the 38.5- and 37-kD proteins than did the other isolates. Outer membrane protein profiles of E ictaluri derived from Bengal danio (Danio devario) and walking catfish (Clarias batrachus) were identical to OMP profiles of isolates from channel catfish. In contrast, OMP profiles from single isolates from green knife fish (Eigemannia virescens) and white catfish (Ictalurus catus) were different. Variations in incubation time, SLS extraction time, SLS extraction number, and in vivo and in vitro passage had no effect on the OMP profile of E ictaluri ATCC 33202. An increase in duration of sample solubilization did affect the OMP profile of E ictaluri ATCC 33202 by decreasing the amount of protein in 52-, 46-, and 43.5-kD bands. Accompanying the decrease were increased staining intensity in the 31.5- and 28.5-kD bands and the appearance of 4 new bands (34, 33, 25.5, and 22.5 kD). Edwardsiella ictaluri, a gram-negative bacterium in the family Enterobacteriaceae, is the cause of enteric septicemia of catfish.(ABSTRACT TRUNCATED AT 250 WORDS)     

Susceptibility of oat cultivars to groat discoloration: causes and remedies

Fungal isolations and fungicide efficacy trials were carried out to determine the possible causes of discoloration in oat groats and potential control measures. Alternaria species and Microdochium nivale were isolated from field samples, and Fusarium poae was found in glasshouse tests. Symptoms could be induced reliably in the field through the use of a mist irrigation system. The cultivar ‘Gerald’ was most resistant followed by ‘Jalna’. Cultivar ‘Image’ was most severely affected by discoloration and ‘Millennium’ was of intermediate susceptibility. None of the 28 fungicide‐timing combinations used in the field trials affected the occurrence of discoloured groats. It was concluded that the best strategy for minimizing risk of discoloured groats would be screening new cultivars or breeding material in mist‐irrigated field trials for genetically based resistance.     

Determinants of yield in a non-timber forest product: Copaifera oleoresin in Amazonian extractive reserves

Developing sustainable extractive industries in otherwise intact tropical forest regions requires a sound understanding of the production potential of key resource populations. The oleoresin extracted from Copaifera trees is an economically important non-timber forest product harvested throughout the lowland Amazon basin. We studied oleoresin extraction from four species of Copaifera trees with known harvest histories within two contiguous extractive reserves in western Brazilian Amazonia. We conducted a large-scale experimental harvest of 179 previously unharvested Copaifera trees, in both seasonally flooded (várzea) and adjacent unflooded (terra firme) forests. The likelihood of trees yielding any oleoresin was principally determined by their species identity: C. multijuga was the only species to regularly yield oleoresin (70% of trees). Yield volumes varied both amongst species and forest types: C. multijuga (restricted to terra firme forest) had the highest mean yield of 505 ml, whilst C. guyanensis produced higher volumes of oleoresin in várzea (139 ml) than terra firme (15 ml) forest. Intraspecific differences were driven mainly by tree size. To assess extraction sustainability, we reharvested a sample of C. multijuga trees and compared the oleoresin production of 24 conspecific trees that had been initially harvested one year previously with that of 17 trees initially harvested three years previously. Reharvested trees produced just 35% of the oleoresin volume compared to that when originally drilled, but this response was not affected by the time interval between consecutive harvests. We demonstrate that, within a population of Copaifera, both morphological and environmental factors restrict total productivity; consideration of these factors should inform sustainable management practises. We additionally raise methodological considerations that may improve the comparability of studies.     

Shocked quartz at the triassic-jurassic boundary in Italy

Quartz grains that appear to have been shock-metamorphosed occur within three closely spaced shale beds from the uppermost Triassic ("Rhaetian") Calcare a Rhaetavicula in the Northern Apennines of Italy. The upper shale coincides with the abrupt termination of the distinctive, uppermost Triassic Rhaetavicula fauna and is overlain by the Hettangian (Lower Jurassic) Calcare Massiccio; no extinctions appear to be associated with the two lower layers, which occur 1.2 and 2.4 meters below the boundary shale. Approximately 5 to 10% of the quartz grains within these layers exhibit one or more sets of planar deformational features whose orientations cluster around the rational crystallographic planes (basal, omega, and pi) most commonly observed in shocked quartz. Textural and stratigraphic observations support an interpretation of at least three closely spaced impacts at the end of the Triassic.     

Kyanite-Sillimanite Equilibrium at 750{degrees}C

Reversal of the kyanite-sillimanite inversion has been accomplished hydrothermally at 750 degrees C. The inversion pressure at 750 degrees C is 8.1 +/- 0.4 kilobars. The calculated pressuretemperature slope at this point is 17.7+/- 1.0 bars per degree celsius. Geologically, this result seems more plausible than previous estimates of the location of the boundary. When combined with other work on the relative stability of andalusite, the data indicate that andalulsite cannot be stable at a pressure greater than 4.2 kilobars.     

Cleavage of proBDNF by tPA/plasmin is essential for long-term hippocampal plasticity

Long-term memory is thought to be mediated by protein synthesis-dependent, late-phase long-term potentiation (L-LTP). Two secretory proteins, tissue plasminogen activator (tPA) and brain-derived neurotrophic factor (BDNF), have been implicated in this process, but their relationship is unclear. Here we report that tPA, by activating the extracellular protease plasmin, converts the precursor proBDNF to the mature BDNF (mBDNF), and that such conversion is critical for L-LTP expression in mouse hippocampus. Moreover, application of mBDNF is sufficient to rescue L-LTP when protein synthesis is inhibited, which suggests that mBDNF is a key protein synthesis product for L-LTP expression.     

Projecting impacts of human disturbances to inform conservation planning and management in a dryland forest landscape

Systematic approaches to conservation planning and management require spatially explicit information on the dynamics of multiple disturbance processes, but progress in providing such information has been limited to date. Here we examine the use of a spatially explicit model of forest dynamics (LANDIS-II), incorporating a range of ecological processes, to examine the impacts of different types of disturbance on a dryland forest landscape in Central Chile. The model was parameterized using spatial data and results of a field survey, in which 21 native tree species were recorded, and one invasive exotic (Acacia dealbata). Seven disturbance scenarios were simulated, with different combinations of fire, browsing and tree cutting. Model results indicated relatively little impact of disturbance on forest cover but substantial differences in forest structure, with relatively old-growth forest stands (>120 years old) being virtually eliminated from the landscape in scenarios with both browsing and cutting. Tree species richness tended to be lower in those scenarios without disturbance, highlighting potential trade-offs between forest structure and species richness. Spread of A. dealbata was projected only to occur in the presence of fire when combined with browsing and/or cutting. These interactive effects of different forms of disturbance illustrate the value of process-based modeling approaches for exploring the spatial dynamics of multiple disturbance processes, but highlight the difficulty of identifying an optimum disturbance regime that would enable conservation objectives to be achieved. It is suggested that process-based models should form part of an analytical ‘toolkit’ to support the practical implementation of systematic conservation planning approaches.