Communities of ground-living spiders in six habitats on a mountain in Quebec, Canada

Ground-living spiders were studied, using pitfall traps, in six habitats between 580 and 960 m (deciduous forest, fir forest, forest-line and three alpine mountain top sites) on Mont du Lac des Cygnes. Altogether 88 species of spiders were found during the study summer (June-mid-September 1985), of which 51 belonged to Linyphiidae (s. lat.), 9 to Lycosidae and 8 to Gnaphosidae. The highest species number and diversity were found in the forest-line habitat, the highest individual number on the main summit and the lowest in deciduous forest, the lowest site. Lycosidae and Gnaphosidae species and individuals characterized the alpine habitats. Linyphiidae (especially Linyphiinae) the forested sites and Amaurobiidae and Agelenidae the deciduous forest site. Erigoninae occurred commonly at all sites; their individual numbers were very high at coniferous forest sites. The dominant species in all three alpine habitats was Pardosa concinna , on the forest-line Hybocoptus gibbosus , in balsam fir forest Sisicottus montanus and in deciduous forest Amaurobius borealis . The material included several (sub)arctic-alpine species.     

Interference of cyclosporin with lymphocyte proliferation: effects on mitochondria and lysosomes of cyclosporin-sensitive or -resistant cell clones

Cyclosporin was previously shown to interfere with--but not to abolish--the increased activities of lysosomes and mitochondria consequent to a mitogenic activation of normal mouse lymphocytes. This was evident from the fluorescence profiles of cell populations after vital staining with euchrysine (giving a lysosomal-specific red fluorescence) and rhodamine-123 (giving a mitochondrial-specific green fluorescence). Fluorescence profiles of the population of cells not exposed to a mitogen were also altered by cyclosporin, with lower lysosomal and mitochondrial fluorescence of these cell populations. In order to find out more precisely what could be the direct effects of cyclosporin on those cellular organelles, our cyclosporin-sensitive (BE7) and cyclosporin-resistant (LB7) lymphoblastoid cell lines were tested and showed clear-cut differences. Only minor effects could be detected for the lysosomal and mitochondrial activities of the resistant cells. On the contrary, cyclosporin caused, in the cells of the sensitive clone BE7, a clear decrease of mitochondrial activity together with an unexpected increase of the red fluorescence of euchrysine. The latter might not correspond to a real increase of the lysosomal activity of such cells. Indeed electron microscopy studies do not show higher numbers of lysosomes; rather they show that numerous vacuoles appear in the cytoplasm of the cyclosporin-treated BE7 cells (but not in the cells of the resistant clone and not in untreated cells of either types).     

Characterization of T8 epitopes by enzymatic digestion, crossblocking, and involvement in cell-mediated lympholysis

Eleven monoclonal antibodies, directed versus the T8 glycoprotein, were compared using enzyme digestion, phylogenetic comparisons, cross-blocking of antibody binding, and blocking of specific cell-mediated lympholysis (CML). It was found that none of the 11 anti-T8 antibodies tested define the same epitope on the T8 glycoprotein. Some of these antibodies react, however, with closely related structures, as shown by cross-blocking of antibody binding and similar enzyme sensitivity of the epitopes. Moreover, these structural related epitopes show a similar involvement in the effector phase of CML reactions, since the antibodies to these neighboring epitopes inhibit the same CML reactions. Thus, it is possible to apply structural and functional criteria to define "regions" on the T8 glycoprotein, some of which are consistently involved in CML reactions, some never, and some of these regions appear to be involved in specific effector-target cell combinations only.     

Rainbow trout (Oncorhynchus mykiss) exposed to oxygen supersaturation and handling stress: plasma cortisol and hepatic glutathione status

Three groups of one summer old rainbow trout were exposed for 22 days either to normoxia (100%) or moderate oxygen supersaturation; 120% and 140%. After the exposure, all groups were transported for three hours in hyperoxic conditions (123% O2) thus simultaneously experiencing density and handling stress. The recovery of rainbow trout to multiple stressors was measured in normoxic conditions. Moderate oxygen supersaturation did not have any negative effects on growth, feed conversion and blood hematology measured over 22 days. On the other hand, the combined effects of the stressful environment in the fish farm and oxygen supersaturation resulted in a 3-fold increase in plasma cortisol levels in those with 100% and 120% O2 supersaturation and a 2-fold increase in the 140% supersaturation group. Furthermore, the stress response after transportation was lowest in the 140% group 24 hours after recovery but highest after 70 hours. Moderate hyperoxia or transportation stress did not change glutathione concentrations in liver indicating that routine sampling does not affect hepatic glutathione status. Our results indicate that moderate O2 supersaturation (<140%) could be considered as feasible in cultivation of rainbow trout since no harmful effects were found.     

Diverse population trajectories among coexisting species of subarctic forest moths

Records of 232 moth species spanning 26 years (total catch of ca. 230,000 specimens), obtained by continuous light-trapping in Kevo, northernmost subarctic Finland, were used to examine the hypothesis that life-history traits and taxonomic position contribute to both relative abundance and temporal variability of Lepidoptera. Species with detritophagous or moss-feeding larvae, species hibernating in the larval stage, and species pupating during the first half of the growing season were over-represented among 42 species classified as abundant during the entire sampling period. The coefficients of variation in annual catches of species hibernating as eggs averaged 1.7 times higher than those of species hibernating as larvae or pupae. Time-series analysis demonstrated that periodicity in fluctuations of annual catches is generally independent of life-history traits and taxonomic affinities of the species. Moreover, closely related species with similar life-history traits often show different population dynamics, undermining the phylogenetic constraints hypothesis. Species with the shortest (1 year) time lag in the action of negative feedback processes on population growth exhibit the largest magnitude of fluctuations. Our analyses revealed that only a few consistent patterns in the population dynamics of herbivorous moths can be deduced from life-history characteristics of the species. Moreover, the diversity of population behaviour in one moth assemblage challenges any conventional wisdom suggesting predictable patterns. Our results raise several questions about perceptions and paradigms in insect population dynamics and stress the need for research on detritivorous insect population dynamics, as well as the need for more assemblage-wide studies using common trapping methods to provide comparative data on related and unrelated species with different life-history traits.     

The effects of cyclosporins on the cell cycle of T-lymphoid cell lines

Cyclosporin A (CsA) is a cyclic endecapeptide of fungal origin displaying strong immunosuppressive properties. CsA and another active member of the cyclosporin (Cs) family, but not an inactive one, can interfere with the proliferation of some, but not all, T-lymphoid cell lines. Cells from Cs-sensitive lines accumulate in the G1 phase of the cell cycle. No effect is detected on the cycle of Cs-resistant lines. Both Cs-sensitive and Cs-resistant lines are arrested by another G1 blocker (actinomycin D) and DNA synthesis inhibitors (cytosine arabinoside, hydroxyurea), become multinucleated/polyploid when exposed to cytochalasin B (CB), are arrested in mitosis by colchicine and accumulate in G2 phase in the presence of Taxol. The effect of Cs is best evidenced when the drug is applied to cells which were already delayed in G1 by saturation density cultivation or serum deprivation. By the combined use of Cs and of other drugs working at a later phase of the cycle, results were obtained which suggest that the effect of Cs is either to delay very much the cells throughout the G1 phase or to arrest them at that G1 phase or at the following one. A correlation of the G1-blocking property of Cs with their immunosuppressive properties may be possible but is still speculative.     

Water currents and spreading of river load in Lake Pyhäselkä, Saimaa, Finland

During the summers of 1989–1990, the pattern of water flow and the water quality in Lake Pyhäselkä, Finland, were studied using field observations and a 3-dimensional model. The lake receives its major point-source loading, including pulp mill effluents, via the Pielisjoki River in the northeastern part of the lake, where the water is slightly eutrophic. The flow pattern was measured with three types of recording current meters, two of which were conventional mechanical meters and the third a new acoustic current profiler. The profiler was used in direct reading mode on a research vessel and also in self-contained mode on a float installed in the deep basin of the lake. The water-quality part of the model simulates oxygen, BOD, total phosphorus, AOX, and phytoplankton biomass. The three-dimensional model applied here simulates accurately the flow pattern of the water in Lake Pyhäselkä. The results of this study made it possible to detect different flow patterns in the lake. The main load is clearly affected by the wind-induced pattern of flow.     

Cytoplasmic lipid droplets as the possible eventual cellular fate of active forms of cyclosporin

The activity of cyclosporins can be defined with regard to their ability to inhibit the proliferation of susceptible lymphoblastoid cell clones. All active cyclosporins cause the emergence of highly refringent globular bodies, independently of cell susceptibility to cyclosporin. Cyclosporins devoid of proliferation-inhibition capability do not cause such alterations in cell morphology. The use of dansylated active cyclosporins suggests that within a few hours of treatment in vitro, most if not all cyclosporin is contained within those globular bodies. By using cytochemical methods allowing differential staining, we show here that these cyclosporin-containing structures are neither normal mitochondria (shown by use of rhodamine 123) nor normal lysosomes (shown by use of acridine orange under stringent staining conditions) but most probably lipid droplets (shown by use of perylene and various dansylated hydrophobic probes).