Projected climate change effects on Alberta's boreal forests imply future challenges for oil sands reclamation

Climate change will drive significant changes in vegetation cover and also impact efforts to restore ecosystems that have been disturbed by human activities. Bitumen mining in the Alberta oil sands region of western Canada requires reclamation to “equivalent land capability,” implying establishment of vegetation similar to undisturbed boreal ecosystems. However, there is consensus that this region will be exposed to relatively severe climate warming, causing increased occurrence of drought and wildfire, which threaten the persistence of both natural and reclaimed ecosystems. We used a landscape model, LANDIS‐II, to simulate plant responses to climate change and disturbances, forecasting changes to boreal forests within the oil sands region. Under the most severe climate forcing scenarios (representative concentration pathway [RCP] 8.5) the model projected substantial decreases in forest biomass, with the future forest being dominated by drought‐ and fire‐tolerant species characteristic of parkland or prairie ecosystems. In contrast, less extreme climate forcing scenarios (RCPs 2.6 and 4.5) had relatively minor effects on forest composition and biomass with boreal conifers continuing to dominate the landscape. If the climate continues to change along a trajectory similar to those simulated by climate models for the RCP 8.5 forcing scenario, current reclamation goals to reestablish spruce‐dominated boreal forest will likely be difficult to achieve. Results from scenario modeling studies such as ours, and continued monitoring of change in the boreal forest, will help inform reclamation practices, which could include establishment of species better adapted to warmer and drier conditions.     

Effect of different dietary fat sources on production traits, lipid peroxide status and on the glutathione redox system in African catfish [Clarias gariepinus (Burchell)] fingerlings. Short communication

Lipids are used to provide the energy to cover the metabolic needs and to provide essential fatty acids, which are important for membrane function [12]. Fats may contain high level of long chain polyunsaturated fatty acids, which are prone to peroxidation [8] and will interact with the antioxidant defense system [1]. There is contradiction in the literature about whether the intake of fish oil enhance [7] or deplete [4] tissue antioxidant defenses and the glutathione redox system in different organisms. The aim of the present study was to examine the effects of different dietary oils on parameters of the lipid peroxide state and the glutathione redox system in C. gariepinus fingerlings.     

Expression inEscherichia coli of active human alcohol dehydrogenase lacking N-terminal acetylation

Human alcohol dehydrogenase (ADH, tiff isozyme of class I) was expressed in Escherichia coli, purified to homogeneity, and characterized regarding N-terminal processing. The expression system was obtained by ligation of a cDNA fragment corresponding to the fl-subunit of human liver alcohol dehydrogenase into the vector pKK 223-3 containing the tac promoter. The enzyme, detected by Western-blot analysis and ethanol oxidizing activity, constituted up to 3 ~o of the total amount of protein. Recombinant ADH was separated from E. coli ADH by ion-exchange chromatography and the isolated enzyme was essentially pure as judged by SDS-polyacrylamide gel electrophoresis and sequence analysis. The N-terminal sequence was identical to that of the authentic fl-subunit except that the N-terminus was non-acetylated, indicating a correct removal of the initiator methionine, but lack of further processing.     

Virus-mediated induction in human lymphocytes of antibody-independent cytotoxicity (VDCC) and enhancement of antibody-dependent cytotoxicity (ADCC) against natural killer-resistant tumor target cells

The effect of Parotis virus on the in vitro cytotoxicity of human lymphocytes against NK-resistant mouse mastocytoma cells was studied. In the ⁵¹Cr-release assay, treatment of lymphocytes with virus induced a rapid cytotoxicity in the absence of anti-P8 15 antibody (virus-dependent cellular Cytotoxicity, VDCC) and strongly enhanced antibody-dependent cytotoxicity (ADCC). At the effector cell level, virus treatment was found to increase the frequency of target-binding cells (TBC) as well as the proportion thereof mediating VDCC and/ or ADCC, indicating recruitment of active effector cells. The recruited cells were heterogeneous but contained a major fraction bearing the T-cell-associated antigen T3. Virus was found to decrease rather than to increase the recycling capacity of the cytotoxic lymphocytes, suggesting that VDCC induction and ADCC enhancement were due to a virus-mediated improvement of effector cell-target cell interactions. VDCC and ADCC enhancement may be of protective importance in early phases of virus infection as well as for the production of nonspecific tissue injuries associated with viral disease.     

Immunoelectrophoretic analysis of erythrocytic stages of Plasmodium yoelii and P. chabaudi

Triton X-100 extracts of erythrocytes infected with Plasmodium chabaudi and P. yoelii were analysed in crossed immunoelectrophoresis with rabbit antisera. The parasite origin of the antigens detected was assessed by metabolic radiolabelling of the parasites with 35S-methionine. About 12 immunoprecipitates were obtained with both extracts and their homologous antiserum. Cross-tests showed that the two parasite strains were very similar antigenically. Species-specific antigens could, however, also be demonstrated. Two antigens, present on both P. yoelii- and P. chabaudi-infected erythrocytes, were located on the surface of the host cell membrane as judged from 125I-labellings with lactoperoxidase. Experiments with phenyl-Sepharose showed that most of the antigens detected were hydrophilic and none of them reacted with concanavalin A.     

Active gamma-secretase is localized to detergent-resistant membranes in human brain

Several lines of evidence suggest that polymerization of the amyloid beta-peptide (Abeta) into amyloid plaques is a pathogenic event in Alzheimer's disease (AD). Abeta is produced from the amyloid precursor protein as the result of sequential proteolytic cleavages by beta-secretase and gamma-secretase, and it has been suggested that these enzymes could be targets for treatment of AD. gamma-Secretase is an aspartyl protease complex, containing at least four transmembrane proteins. Studies in cell lines have shown that gamma-secretase is partially localized to lipid rafts, which are detergent-resistant membrane microdomains enriched in cholesterol and sphingolipids. Here, we studied gamma-secretase in detergent-resistant membranes (DRMs) prepared from human brain. DRMs prepared in the mild detergent CHAPSO and isolated by sucrose gradient centrifugation were enriched in gamma-secretase components and activity. The DRM fraction was subjected to size-exclusion chromatography in CHAPSO, and all of the gamma-secretase components and a lipid raft marker were found in the void volume (> 2000 kDa). Co-immunoprecipitation studies further supported the notion that the gamma-secretase components are associated even at high concentrations of CHAPSO. Preparations from rat brain gave similar results and showed a postmortem time-dependent decline in gamma-secretase activity, suggesting that DRMs from fresh rat brain may be useful for gamma-secretase activity studies. Finally, confocal microscopy showed co-localization of gamma-secretase components and a lipid raft marker in thin sections of human brain. We conclude that the active gamma-secretase complex is localized to lipid rafts in human brain.     

Immunofluorescence studies of developmental changes in sea urchin eggs and embryos

By means of indirect immunofluorescence techniques, distinct sea urchin antigens were localized in eggs and embryos (Paracentrotus lividus). The specificity of the method was ascertained from controls in which the specific rabbit anti-sea-urchin sera were substituted by rabbit antiserum to an unrelated antigen (human serum albumin), by normal rabbit serum or by phosphate-buffered saline. The specificity of staining was also evaluated by comparing the different staining patterns obtained either with antisera to whole homogenates of eggs and embryos or with antisera to distinct antigens.