Nucleotide polymorphisms associated with climate,phenology and physiological traits in European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

Although European beech (Fagus sylvatica L.) is one of the most widespread and ecologically and commercially most important deciduous trees in Europe, little is known about its adaptive genetic variation. We explored single-nucleotide polymorphism (SNP) variation in candidate genes for budburst and drought resistance in beech populations sampled across most of the distribution range, represented in an international provenance trial. SNP variation was monitored for six candidate genes, in 114 individuals from 19 natural populations. Population structure was deduced from the analysis of 20 nuclear microsatellite markers. Different methods to detect imprints of natural selection were used (F _ST-outlier, SNP-climate regression, association tests). The F _ST-outlier approach identified the COV gene with unambiguous signal of selection, which is an orthologue of Arabidopsis gene for a membrane protein previously reported as phenology-related. Based on environmental association analysis at the population level, the dehydrin gene was found associated with drought-related climatic variables. At the individual level, dehydrin gene also showed a significant association with chlorophyll fluorescence parameters, which are considered stress markers. The importance of the knowledge of physiological variation and geographical patterns of adaptive genetic variation for guiding reproductive materials transfer under climate change is stressed.     

Gamma/delta T-cell lymphoma in a dog

A 15-month-old dachshund was presented for examination because of a cough. Thoracic radiographs revealed the presence of a mass in the upper mediastinum. A diagnosis of γδ T-cell lymphoma was made by biopsy and flow cytometry analysis. The dog was treated with chemotherapy and remains asymptomatic after 24 months.     

Nitrous oxide emissions from cattle-impacted pasture soil amended with nitrate and glucose

There is little information concerning N₂O fluxes in the pasture soil that has received large amounts of nutrients, such as urine and dung, for several years. The aims of this study were to (1) experimentally quantify the relationship between mineral N input and N₂O emissions from denitrification, (2) describe the time course of N₂O fluxes resulting in N inputs, and (3) find whether there exists an upper limit of the amount of nitrogen escaping the soil in the form of N₂O. The study site was a grassland used as a cattle overwintering area. It was amended with KNO₃ and glucose corresponding to 10–1,500 kg N and C per hectare, covering the range of nutrient inputs occurring in real field conditions. Using manual permanent chambers, N₂O fluxes from the soil were monitored for several days after the amendments. The peak N₂O emissions were up to 94 mg N₂O–N m⁻² h⁻¹, 5–8 h after amendment. No upper limit of N₂O emissions was detected as the emissions were directly related to the dose of nutrients in the whole range of amendments used, but the fluxes reflected the soil and environmental conditions, too. Thus, in three different experiments performed during the season, the total cumulative losses of N₂O–N ranged from 0.2 to 5.6% of the applied 500kg ha⁻¹. Splitting of high nutrient doses lowered the rate of N₂O fluxes after the first amendment, but the effect of splitting on the total amount of N₂O–N released from the soil was insignificant, as the initial lower values of emissions in the split variants were compensated for by a longer duration of gas fluxes. The results suggest that the cattle-impacted soil has the potential to metabolize large inputs of mineral nitrogen over short periods (∼days). Also, the emission factors for did not exceed values reported in literature.     

A microsporidian pathogen of the predatory beetle Rhizophagus grandis (Coleoptera: Rhizophagidae)

A new Microsporidium sp. infects Rhizophagus grandis Gyllenhall, a beetle which preys on the bark beetle Dendroctonus micans Kugellan in Turkey. Mature spores are single, uninucleate, oval in shape (3.75 +/- 0.27 microm in length by 2.47 +/- 0.13 microm in width), with a subapically fixed polar filament. The polar filament is anisofilar, coiled in 7-8 normal and 3-4 reduced coils. Other characteristic features of the microsporidium are the four/five nuclear divisions to form 16/32 (commonly 16) spores, subpersistent sporophorous vesicles (pansporoblasts) remaining till formation of the endospore, and the vesicles dissolved with free mature spores. The polaroplast is divided into three zones: an amorphous zone, dense layers, and a lamellartubular area extending to the central part of the spore.     

Enzyme activities and microbial biomass in topsoil layer during spontaneous succession in spoil heaps after brown coal mining

Changes in the activity of extracellular enzymes (cellobiohydrolase, β-glucosidase, β-xylosidase, chitinase, arylsulfatase and phosphatases) and the changes in microbial community and abiotic properties in the topsoil layer, as well as soil abiotic properties during primary succession were investigated in a brown coal mine deposit area near Sokolov, Czech Republic. The study considered the chronosequence of 4 post-mining plots, 4-, 12-, 21- and 45-year old. The 4-year old site had no vegetation cover. Herbs and grasses (mainly Calamagrostis epigeios) were present on the 12-year old plot, shrubs (Salix caprea) occurred on the 21-year old plot and tree cover (Betula spp. and Populus tremuloides) developed on the 45-year old plot. Soil pH gradually decreased with site age, while the content of P, K, C and N peaked in the 21-year old site, being significantly lower in the 45-year old site and much lower in the 4- and 12-year old sites. Phosphatase activities were strongly affected by seasonality while the activities of all the other enzymes measured were more influenced by the effects of succession age and soil layer than by seasonality. Succession age was also the most important factor affecting the total and bacterial PLFA contents, followed by the effects of soil layer and season while for the fungal biomass content-related properties (ergosterol, fungal PLFA and the fungal/bacterial PLFA ratio), season was the most important. Activities of individual enzymes in the topsoil (0–5 cm depth) were significantly affected by both site age and season. Cellobiohydrolase and β-xylosidase were more affected by site age while chitinase and phosphatases were more affected by season. Enzyme activity increased with succession age. Comparison of the effect of site and season on enzyme activity showed that season played a principal role in the enzyme activity of the entire 0–5 cm component of topsoil, as well the soil layers when evaluated separately.