Interferon affects the formation of adhesion plaques in human monocyte cultures

When monocytes isolated from human blood adhere to glass substratum, actin- and vinculin-containing punctate plaques rapidly appear at the ventral surface of the cells. We show here that highly purified human leukocyte interferon (IFN) can inhibit formation of these adhesion plaques in a dose-dependent manner. Complete inhibition was obtained when 300 IU/ml IFN were added into the cell-seeding medium. Plaques already formed in the absence of IFN were only partially affected by subsequent addition of IFN into the culture medium. Prevention by IFN of the formation of the adhesion plaques was associated with loosened attachment of the cells to the substratum. Effect of IFN on cellular morphology was complex. At higher doses, IFN added to the cultures within 24 h of seeding almost completely inhibited the differentiation of monocytes to macrophages and most of the cells remained rounded. At lower doses, however, an enhancement of the bipolar spreading was seen and the end result was a culture with predominantly elongated fibroblastoid cells. The latter cells, unlike the fibroblastoid cells in untreated monocyte-macrophage cultures, were completely devoid of the actin plaques, while the reorganization of vimentin-type intermediate filaments took place in a normal manner. These results further support the view that the actin- and vinculin-containing plaques have a role in mediating firm adherence of human monocytes to growth substratum.     

Lymphoid cell subclasses in rejecting renal allograft in the rat

We have quantitated the frequency of lymphoid cell subsets in rejecting renal allografts and in the spleen of the allograft recipient during drug-unmodified rejection in the rat. The number of inflammatory (white) cells in the graft was approximately similar to the number of white cells responding to the allograft in the recipient spleen. The inflammatory population of the graft consisted of lymphoid cells and mononuclear phagocytes, with increasing numbers of macrophages toward the end of rejection. Analysis of allograft cellular dispersates with monoclonal antibodies directed to the lymphoid cell subsets demonstrated that although the majority of allograft-infiltrating lymphocytes were T cells, a sizable B-cell proliferation and immunoglobulin synthesis was associated with the inflammatory response of rejection. Within the T-cell subset, the T suppressor/killer cells predominated in the graft whereas the predominant lymphoid cell subset responding to the allograft in the recipient spleen was the T helper cell.     

Differentiation and vascularization of the metanephric kidney grafted on the chorioallantoic membrane

The origin and development of mouse kidney vasculature were examined in chorioallantoic grafts of early kidney rudiments and of experimentally induced explants of separated metanephric mesenchymes. Whole kidney rudiments developed into advanced stages, expressed the segment-specific antigenic markers of tubules and the polyanionic coat of the glomeruli. In contrast to development in vitro, these grafts regularly showed glomeruli with an endothelial component and a basement membrane expressing type IV collagen and laminin. The glomerular endothelial cells in these grafts were shown to carry the nuclear structure of the host. This confirms the outside origin of these cells and the true hybrid nature of the glomeruli. When in vitro induced mesenchymes were grafted on chorioallantoic membranes, abundant vascular invasion was regularly found but properly vascularized glomeruli were exceptional. Uninduced, similarly grafted mesenchymal explants remained avascular as did the undifferentiated portions of partially induced mesenchymal blastemas. It is concluded that the stimulation of the host endothelial cells to invade into the differentiating mesenchyme requires the morphogenetic tissue interaction between the ureter bud and the mesenchyme. The induced metanephric cells presumably start to produce chemoattractants for endothelial cells at an early stage of differentiation. Kidney development thus seems to require an orderly, synchronized development of the three cell lineages: the branching ureter, the induced, tubule-forming mesenchyme, and the invading endothelial cells of outside origin.     

Recognition of extracellular matrix components by neonatal and adult cardiac myocytes

The histogenesis of renal basement membranes was studied in grafts of avascular, 11-day-old mouse embryonic kidney rudiments grown on chick chorioallantoic membrane (CAM). Vessels of the chick CAM invade the mouse tissue during an incubation period of 7-10 days and eventually hybrid glomeruli composed of mouse epithelium and chick endothelium form. Formation of basement membranes during this development was followed by immunofluorescence and immunoperoxidase stainings using polyclonal and monoclonal antibodies against mouse and chick collagen type IV and against mouse laminin. These antibodies were species-specific as shown in immunochemical and immunohistologic analyses. The glomerular basement membrane contained both mouse and chick collagen type IV, demonstrating its dual cellular origin. All other basement membranes were either exclusively of chick origin (mesangium, vessels) or of mouse origin (tubuli, Bowman's capsule).     

Integrated lake monitoring in Europe the macrozoobenthos in the four target lakes in Finland

In four small ( 1 km²) Finnish lakes belonging to the Integrated Monitoring Programme (UN ECE), macrozoobenthos has been studied at different depths since 1989. The lakes are situated between 61°N–70°N latitudes from the southern boreal coniferous region up to the forest tundra ecotone. The macrozoobenthos of the lakes was very different compared to each other, but chironomids were important in all lakes. Acid-sensitive taxa (molluscs, some mayflies) were lacking in one of the lakes because of its low pH. In all lakes the zoobenthos could indicatee.g. the wideness of the littoral region and stagnation conditions or groundwater input through the bottom. In future, both litoral and profundal sampling is needed because of the multi-purpose character of the monitoring (acidification, trophic level).     

Ecological status of some Finnish rivers evaluated using benthic diatom communities

The applicability of some diatom methods to quality assessment of differenttypes of Finnish rivers was compared using dominant taxa of diatomcommunities and nutrient level estimations using Trophic Diatom Index(TDI) and a new Phosphorus Diatom Equation (PDE) [Tot. P_calc (g l^-1) = 39 – 0.278 ol-% – 0.117 olme-% – 0.346me-% – 0.006 meeu-% + 1.193 eu-%; n = 97; r² = 0.742;SE = 17.4]. The overall quality estimations were done by Index ofPollution Sensitivity (IPS) and by Generic Diatom Index (GDI); limit valuesfor quality classes are proposed.     

Regional and local drivers of macroinvertebrate assemblages in boreal springs

Aim To identify the most important environmental drivers of benthic macroinvertebrate assemblages in boreal springs at different spatial scales, and to assess how well benthic assemblages correspond to terrestrially derived ecoregions. Location Finland. Methods Benthic invertebrates were sampled from 153 springs across four boreal ecoregions of Finland, and these data were used to analyse patterns in assemblage variation in relation to environmental factors. Species data were classified using hierarchical divisive clustering (twinspan ) and ordinated using non‐metric multidimensional scaling. The prediction success of the species and environmental data into a priori (ecoregions) and a posteriori (twinspan ) groups was compared using discriminant function analysis. Indicator species analysis was used to identify indicator taxa for both a priori and a posteriori assemblage types. Results The main patterns in assemblage clusters were related to large‐scale geographical variation in temperature. A secondary gradient in species data reflected variation in local habitat structure, particularly abundance of minerogenic spring brooks. Water chemistry variables were only weakly related to assemblage variation. Several indicator species representing southern faunistic elements in boreal springs were identified. Discriminant function analysis showed poorer success in classifying sites into ecoregions based on environmental than on species data. Similarly, when classifying springs into the twinspan groups, classification based on species data vastly outperformed that based on environmental data. Main conclusions A latitudinal zonation pattern of spring assemblages driven by regional thermal conditions is documented, closely paralleling corresponding latitudinal patterns in both terrestrial and freshwater assemblages in Fennoscandia. The importance of local‐scale environmental variables increased with decreasing spatial extent. Ecoregions provide an initial stratification scheme for the bioassessment of benthic macroinvertebrates of North European springs. Our results imply that climate warming, landscape disturbance and degradation of spring habitat pose serious threats to spring biodiversity in northern Europe, especially to its already threatened southern faunistic elements.     

The role of land cover in bioclimatic models depends on spatial resolution

Aim We explored the importance of climate and land cover in bird species distribution models on multiple spatial scales. In particular, we tested whether the integration of land cover data improves the performance of pure bioclimatic models. Location Finland, northern Europe. Methods The data of the bird atlas survey carried out in 1986–89 using a 10 × 10 km uniform grid system in Finland were employed in the analyses. Land cover and climatic variables were compiled using the same grid system. The dependent and explanatory variables were resampled to 20‐km, 40‐km and 80‐km resolutions. Generalized additive models (GAM) were constructed for each of the 88 land bird species studied in order to estimate the probability of occurrence as a function of (1) climate and (2) climate and land cover variables. Model accuracy was measured by a cross‐validation approach using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Results In general, the accuracies of the 88 bird–climate models were good at all studied resolutions. However, the inclusion of land cover increased the performance of 79 and 78 of the 88 bioclimatic models at 10‐km and 20‐km resolutions, respectively. There was no significant improvement at the 40‐km resolution. In contrast to the finer resolutions, the inclusion of land cover variables decreased the modelling accuracy at 80km resolution. Main conclusions Our results suggest that the determinants of bird species distributions are hierarchically structured: climatic variables are large‐scale determinants, followed by land cover at finer resolutions. The majority of the land bird species in Finland are rather clearly correlated with climate, and bioclimate envelope models can provide useful tools for identifying the relationships between these species and the environment at resolutions ranging from 10 km to 80 km. However, the notable contribution of land cover to the accuracy of bioclimatic models at 10–20‐km resolutions indicates that the integration of climate and land cover information can improve our understanding and model predictions of biogeographical patterns under global change.     

Redescription of Besnoitia tarandi (Protozoa: Apicomplexa) from the reindeer (Rangifer tarandus)

Besnoitia tarandi tissue cysts were found in naturally-infected reindeer (Rangifer tarandus) from Finland. Infectivity of its tissue cysts, bradyzoites, and tachyzoites to animals and cell culture was studied. The bradyzoites and tissue cysts were not infectious to out-bred mice, rabbits or gerbils. When fed tissue cysts, neither cats nor dogs excreted oocysts. However, the parasite was lethal to interferon-gamma gene knock out mice irrespective of the route of inoculation. The parasite was grown successfully in African Green Monkey cells from tissues of two reindeer for the first time. Non-dividing, uninucleate tachyzoites from smears from cell cultures were 5.6 x 1.4 microm (4.5-7.4 x 1.0-1.9, n=50) in size. Longitudinally-cut bradyzoites in tissue sections measured 7.4 x 1.3 microm (6.5-7.8 x 1.0-1.6, n=30). Ultrastructurally, tachyzoites and bradyzoites were similar to those in other Besnoitia species, and in particular to parasites described from cattle (Besnoitia besnoiti) and equids (Besnoitia bennetti) in that their bradyzoites lacked enigmatic bodies. Based on comparative analysis of three portions of nuclear ribosomal DNA (the small and large subunits and the first internal transcribed spacer) B. tarandi was found to be more closely related to the other congeners described from ungulates. The parasite was formally redescribed and specimens deposited in the US National Parasite Collection.     

Determinants of the biogeographical distribution of butterflies in boreal regions

Aim  We explored the relative contributions of climatic and land-cover factors in explaining the distribution patterns of butterflies in a boreal region.
Location  Finland, northern Europe.
Methods  Data from a national butterfly atlas survey carried out during 1991–2003, with a 10-km grain grid system, were used in these analyses. We used generalized additive models (GAM) and hierarchical partitioning (HP) to explore the main environmental correlates (climate and land-cover) of the realized niches of 98 butterfly species. The accuracy of the distribution models (GAMs) was validated by resubstitution and cross-validation approaches, using the area under the curve (AUC) derived from the receiver operating characteristic (ROC) plots.
Results  Predictive accuracies of the 98 individual environment–butterfly models varied from low to very high (cross-validated AUC values 0.48–0.99), with a mean of 0.79. The results of both the GAM and HP analyses were broadly concordant. Most of the variation in butterfly distributions is associated with growing degree-days, mean temperature of the coldest month and cover of built-up area in all six phylogenetic groups (butterfly families). There were no statistically significant differences in predictive accuracy among the different butterfly families.
Main conclusions  About three-quarters of the distributions of butterfly species in Finland appear to be governed principally by climatic, predominantly temperature-related, factors. This indicates that many butterfly species may respond rapidly to the projected climate change in boreal regions. By determining the ecological niches of multiple species, we can project their range shifts in response to changes in climate and land-cover, and identify species that are particularly sensitive to forecasted global changes.