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81.
Laakkonen J Nyyssönen T Hiltunen M Kauhala K Nikander S Soveri T 《Journal of wildlife diseases》2006,42(4):780-787
Mountain hares (Lepus timidus) and brown hares (Lepus europaeus) shot by hunters in several game management districts in southern and central Finland during the hunting season from September to the end of February 1998-2001 were examined for Protostrongylus sp. and Pneumocystis sp. Of the mountain hares, 96.5% (194/201) were infected with the lungworm Protostrongylus sp. and 16.9% (32/189) had cyst forms of the fungus Pneumocystis sp. in the lungs. The prevalence of the lungworm and fungus in brown hares was 60% (18/30) and 20.0% (6/30), respectively. The tissue changes associated with the lungworms were macroscopically and microscopically well demarcated. The majority and most severe histopathologic changes were seen at the distal part of the caudal lobes. Inflammatory cells, mainly eosinophils and macrophages, and in lesser degree neutrophils, lymphocytes, and plasma cells were typical findings in the worm-infected tissue. The condition and weight of the hare did not show any significant association with the intensity of the lungworm infection. All Pneumocystis-infected mountain hares were young, and their condition and weight correlated negatively with the intensity of the infection. The intensity of the Pneumocystis infection did not correlate with that of the lungworm infection. Within a tissue section, a slight but significant positive correlation was observed between presence of cysts and inflammatory cells. 相似文献
82.
Oftedal L Myhren L Jokela J Gausdal G Sivonen K Døskeland SO Herfindal L 《Biochimica et biophysica acta》2012,1818(12):3000-3009
The two novel cyanobacterial cyclic lipopeptides, anabaenolysin (Abl) A and B permeabilised mammalian cells, leading to necrotic death. Abl A was a more potent haemolysin than other known biodetergents, including digitonin, and induced discocyte-echinocyte transformation in erythrocytes. The mitochondria of the dead cells appeared intact with regard to both ultrastructure and membrane potential. Also isolated rat liver mitochondria were resistant to Abl, judged by their ultrastructure and lack of cytochrome c release. The sparing of the mitochondria could be related to the low cholesterol content of their outer membrane. In fact, a supplement of cholesterol in liposomes sensitised them to Abl. In contrast, the prokaryote-directed cyclic lipopeptide surfactin lysed preferentially non-cholesterol-containing membranes. In silico comparison of the positions of relevant functional chemical structures revealed that Abl A matched poorly with surfactin in spite of the common cyclic lipopeptide structure. Abl A and the plant-derived glycolipid digitonin had, however, predicted overlaps of functional groups, particularly in the cholesterol-binding tail of digitonin. This may suggest independent evolution of Abl and digitonin to target eukaryotic cholesterol-containing membranes. Sub-lytic concentrations of Abl A or B allowed influx of propidium iodide into cells without interfering with their long-term cell viability. The transient permeability increase allowed the influx of enough of the cyanobacterial cyclic peptide toxin nodularin to induce apoptosis. The anabaenolysins might therefore not only act solely as lysins, but also as cofactors for the internalisation of other toxins. They represent a potent alternative to digitonin to selectively disrupt cholesterol-containing biological membranes. 相似文献
83.
Claudia Melis Ivar Herfindal Kaarina Kauhala Reidar Andersen Kjell-Arild Høgda 《Mammalian Biology》2010,75(2):151-159
Annual variation in the environment is expected to influence individual performance, e.g. measured as body condition, such as body mass or fat deposition, through its direct or indirect effects on food abundance and availability. Such environmental variation is traditionally measured by climatic observation, but recently, measures of environmental phenology obtained from satellite images have been successfully used. We examined the performance of climatic and plant phenology variables in explaining body condition of an invasive omnivore species: the raccoon dog Nyctereutes procyonoides. We collected data on fat deposition of juveniles in southern Finland from the end of June to the beginning of November. A four-parametric logistic model was fitted separately for each province to the data by non-linear regression procedure and the residuals were compared to the expected average as measure of individual performance. These values were then analysed with respect to the environmental variables. Climatic variables describing spring conditions performed better than plant phenology variables in explaining the variation in fat deposition. Harsh spring conditions negatively affected the amount of fat deposed during the growing season. Plant phenology variables, effective in explaining life history traits in herbivores, might not reflect variation in food abundance and quality for omnivore species. We propose that in Europe raccoon dogs will benefit from climate warming, because of a longer growing season, but increased spring precipitation in the form of snow at higher latitudes might compensate for the effect of greater primary productivity and outline the border of their expansion towards harsher environments. 相似文献
84.
David P. Fewer Miikka Köykkä Katrianna Halinen Jouni Jokela Christina Lyra Kaarina Sivonen 《Environmental microbiology》2009,11(4):855-866
The late summer mass occurrences of cyanobacteria in the Baltic Sea are among the largest in the world. These blooms are rarely monotypic and are often composed of a diverse assemblage of cyanobacteria. The toxicity of the blooms is attributed to Nodularia spumigena through the production of the hepatotoxic nodularin. However, the microcystin hepatotoxins have also been reported from the Baltic Sea on a number of occasions. Recent evidence links microcystin production in the Gulf of Finland directly to the genus Anabaena . Here we developed a denaturing gradient gel electrophoresis (DGGE) method based on the mcyE microcystin synthetase gene and ndaF nodularin synthetase gene that allows the culture-independent discrimination of microcystin- and nodularin-producing cyanobacteria directly from environmental samples. We PCR-amplified microcystin and nodularin synthetase genes from environmental samples taken from the Gulf of Finland and separated them on a denaturing gradient gel using optimized conditions. Sequence analyses demonstrate that uncultured microcystin-producing Anabaena strains are genetically more diverse than previously demonstrated from cultured strains. Furthermore, our data show that microcystin-producing Anabaena are widespread in the open Gulf of Finland. Non-parametric statistical analysis suggested that salinity plays an important role in defining the distribution of microcystin-producing Anabaena . Our results indicate that microcystin-producing blooms are a persistent phenomenon in the Gulf of Finland. 相似文献
85.
Timo K. Korhonen Ritva Virkola Kaarina Lähteenmäki Yvonne Björkman Maini Kukkonen Tiina Raunio Ann-Mari Tarkkanen Benita Westerlund 《FEMS microbiology letters》1992,100(1-3):307-312
A mechanism for penetration of basement membranes by Escherichia coli is presented. The mechanism is based on the ability of the S fimbriae of meningitis-associated E. coli to bind to vascular endothelium and choroid plexuses in brain and to basement membranes. On the other hand, the S and the type 1 fimbriae of E. coli immobilize plasminogen and tissue-type plasminogen activator; this process generates proteolytic plasmin activity on the surface of fimbriate cells. Our hypothesis is that bacterium-bound plasma activity, directed to basement membranes through fimbrial binding, promotes bacterial penetration through basement membranes. 相似文献
86.
The aim of the present study was to examine how the vegetation structure of the forest, shrub and field and ground layer affect
the habitat use of mountain haresLepus timidus Linnaeus, 1759 in summer (May–September) in southern Finland. The structure of each vegetation layer in woodlots throughout
the entire study area of 20 km2 was measured. We analysed the vegetation data using principal component analyses (PCA) that arranged the woodlots along a
gradient within each vegetation layer. Data on habitat use was gathered between 1998 and 2000 from 11 radio-collared mountain
hares. The core areas of the home ranges of hares were determined and the vegetation structure of these areas was compared
with the mean of the entire study area (core area, periphery area and control area). A similar shrub layer gradient was identified
by PCA for seven out of the 11 hares. Hares preferred thickets of willowSalix spp., downy birchBetula pubescens, and sprucePicea abies. The hares did not show a consistent preference for the forest and ground levels. The results suggest that dense understories
are important in the mountain hare’s habitat use, probably because they offer both food and shelter. 相似文献
87.
Halinen K Fewer DP Sihvonen LM Lyra C Eronen E Sivonen K 《FEMS microbiology ecology》2008,64(2):199-208
Late summer cyanobacterial blooms in the Baltic Sea contain Anabaena sp. together with Nodularia spumigena and Aphanizomenon flos-aquae. Although Anabaena is common especially in the Gulf of Finland, very little is known about its genetic diversity. Here we undertook a molecular phylogenetic study of 68 Anabaena strains isolated from the brackish Gulf of Finland. We sequenced the 16S rRNA genes from 54 planktonic and 14 benthic Anabaena strains, and rbcL and rpoC1 genes from a subset of these strains. Phylogenetic trees showed that Anabaena strains, from both planktonic and benthic habitats, were genetically diverse. Although the Anabaena strains were morphologically diverse, in our study only one genetically valid species was found to exist in the plankton. Evolutionary distances between benthic Anabaena strains were greater than between planktonic strains, suggesting that benthic habitats allow for the maintenance of greater genetic diversity than planktonic habitats. A number of novel lineages containing only sequences obtained in this study were compiled in the phylogenetical analyses. Thus, it seemed that novel lineages of the genus Anabaena may be present in the Baltic Sea. Our results demonstrate that the Baltic Sea Anabaena strains show surprisingly high genetic diversity. 相似文献
88.
Diet of raccoon dogs in summer in the Finnish archipelago 总被引:1,自引:0,他引:1
The diet of raccoon dogs in summer was examined in the Finnish archipelago and compared with their diet on the mainland. Faeces were collected from latrines in the outer archipelago and the inhabited islands in May-July 1998 and 1999. Remains of waterfowl, especially those of female cider, occurred frequently in the faeces of raccoon dogs on the uninhabited islands, but less frequently on the inhabited islands and only occasionally on the mainland. Since many female eider died of disease during the summer in 1998 and 1999. and white-tailed eagles arc known to prey on brooding eider, it is probable that raccoon dogs did not themselves kill all the eider they consumed. Even if they did, they would only take a few percent of female eider population each year. It is thus improbable that raccoon dogs affect the size of the eider population in the Finnish archipelago. Frogs, reptiles, shrews and carrion occurred frequently in the diet on the mainland, but only occasionally in the outer archipelago. It is possible that raccoon dogs have decimated frog populations on small islands, as they are easy prey and occur frequently in the diet of raccoon dogs on the mainland. Small rodents are important prey for raccoon dogs on the mainland and on inhabited islands, but less important in the outer archipelago in early summer. 相似文献
89.
If herbivory is unevenly distributed among different types of plants, or if individual plants differ in their response to herbivory, herbivores may affect seedling growth and survival, and consequently plant population structure. In this study we examined variation in resistance to insect herbivory and in growth responses to feeding among 20 silver birch (Betula pendula Roth) genotypes representing variation within a natural population. Birch seedlings were grown in dense stands in random arrangement so that seedlings of different genotypes competed with each other. On insect exposure plots natural colonization of insects was allowed, and insect removal plots were sprayed with insecticide. Resistance to insect herbivory was measured as the inverse of leaf damage, and growth responses of seedlings to feeding were determined as the change in seedling height relative to the amount of damage. Resistance varied significantly among genotypes, but growth responses to feeding did not. In fertilized seedlings, resistance correlated negatively with height, indicating a trade-off between resistance and growth. The absence of such a correlation in non-fertilized seedlings is a sign of environmental effects on the cost of resistance. Growth responses to feeding did not correlate with either resistance or growth. Nevertheless, different effects of the actual damage on height increase changed the positions of the genotypes in the size hierarchy of the experimental populations. Thus, even moderate levels of insect herbivory can change the outcome of competitive interactions between birch genotypes.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper. 相似文献
90.
TopBP1 and ATR colocalization at meiotic chromosomes: role of TopBP1/Cut5 in the meiotic recombination checkpoint 下载免费PDF全文
Perera D Perez-Hidalgo L Moens PB Reini K Lakin N Syväoja JE San-Segundo PA Freire R 《Molecular biology of the cell》2004,15(4):1568-1579
Mammalian TopBP1 is a BRCT domain-containing protein whose function in mitotic cells is linked to replication and DNA damage checkpoint. Here, we study its possible role during meiosis in mice. TopBP1 foci are abundant during early prophase I and localize mainly to histone gamma-H2AX-positive domains, where DNA double-strand breaks (required to initiate recombination) occur. Strikingly, TopBP1 showed a pattern almost identical to that of ATR, a PI3K-like kinase involved in mitotic DNA damage checkpoint. In the synapsis-defective Fkbp6(-/-) mouse, TopBP1 heavily stains unsynapsed regions of chromosomes. We also tested whether Schizosaccharomyces pombe Cut5 (the TopBP1 homologue) plays a role in the meiotic recombination checkpoint, like spRad3, the ATR homologue. Indeed, we found that a cut5 mutation suppresses the checkpoint-dependent meiotic delay of a meiotic recombination defective mutant, indicating a direct role of the Cut5 protein in the meiotic checkpoint. Our findings suggest that ATR and TopBP1 monitor meiotic recombination and are required for activation of the meiotic recombination checkpoint. 相似文献