Characterization of dicyclohexylcarbodiimide binding sites in beef-heart mitochondria.

Binding studies with [¹⁴C]-dicyclohexylcarbodiimide showed the presence of binding sites in the beef-heart mitochondrial membrane at a concentration of 1.8 nmol/mg protein (1.4 sites per cytochrome a+a₃). Saturation of these sites correlated with the inhibition of the ATPase activity. The maximum binding capacity could be related with the amount of F₁-ATPase in mitochondria from various tissues.     

Effects of alkylating agents on lymphocytes from controls and from patients with Fanconi's anemia

Summary The frequency of sister chromatid exchanges (SCE) and chromosome aberrations and the dynamics of cell division in peripheral blood lymphocytes of four patients with Fanconi's anemia were studied after in vitro exposure to alkylating agents TEPA and mitomycin.SCE frequency was significantly increased even after very low doses of mutagens, while chromosome aberrations were significantly increased only after high doses (0.160 g/ml mitomycin and 10^-5 M TEPA). The responses of Fanconi's anemia cells and control cells did not differ significantly. The increased frequency of both SCE and chromosome aberrations was accompanied by gradual delay of cell division, which was most conspicuous in cells from patients with Fanconi's anemia.     

Analysis of purine receptor expression and functionality in alveolar epithelial cells

Despite its fundamental role in providing an extensive surface for gas exchange, the alveolar epithelium (AE) serves as an immunological barrier through, e.g., the release of proinflammatory cytokines and secretion of surfactant to prevent alveolar collapse. Thus, AE is important for sustaining lung homeostasis. Extracellular ATP secreted by alveolar epithelial cells (AECs) is involved in physiological and pathological conditions and acts mainly through the activation of purine receptors (P2Rs). When studying P2R-mediated processes, primary isolated type II AECs (piAECs) still represent the gold standard in in vitro research, although their preparation is time-consuming and requires the sacrifice of many animals. Hence, cultivated immortalized and tumor-derived AEC lines may constitute a valuable alternative. In this work, we examined P2R expression and functionality in piAECs, in immortalized and tumor-derived AEC lines with the purpose of gaining a better understanding of purinergic signaling in different cell systems and assisting researchers in the choice of a suitable cell line with a certain P2R in demand. We combined mRNA and protein analysis to evaluate the expression of P2R. For pharmacological testing, we conducted calcium ([Ca²⁺]) measurements and siRNA receptor knockdown. Interestingly, the mRNA and protein levels of P2Y₂, P2Y_6, and P2X₄ were detected on all cell lines. Concerning functionality, P2XR could be narrowed to L2 and piAECs while P2YR were active in all cell lines.

     

Transmembrane adaptor protein WBP1L regulates CXCR4 signalling and murine haematopoiesis

WW domain binding protein 1‐like (WBP1L), also known as outcome predictor of acute leukaemia 1 (OPAL1), is a transmembrane adaptor protein, expression of which correlates with ETV6‐RUNX1 (t(12;21)(p13;q22)) translocation and favourable prognosis in childhood leukaemia. It has a broad expression pattern in haematopoietic and in non‐haematopoietic cells. However, its physiological function has been unknown. Here, we show that WBP1L negatively regulates signalling through a critical chemokine receptor CXCR4 in multiple leucocyte subsets and cell lines. We also show that WBP1L interacts with NEDD4‐family ubiquitin ligases and regulates CXCR4 ubiquitination and expression. Moreover, analysis of Wbp1l‐deficient mice revealed alterations in B cell development and enhanced efficiency of bone marrow cell transplantation. Collectively, our data show that WBP1L is a novel regulator of CXCR4 signalling and haematopoiesis.     

Phenology and polyploidy in annual Brachypodium species (Poaceae) along the aridity gradient in Israel

Local adaptation of plants along environmental gradients provides strong evidence for clinal evolution mediated by natural selection. Plants have developed diverse strategies to mitigate stress, for example, drought escape is a phenological strategy to avoid drought stress, while polyploidy was proposed as a genomic adaptation to stress. Polyploidy as an adaptation to aridity (an environmental parameter integrating temperature and precipitation) was previously documented in annual Brachypodium spp. (Poaceae) in the Western Mediterranean. Here, we examined whether polyploidy or phenology are associated with aridity in annual Brachypodium spp. along the aridity gradient in the Eastern Mediterranean. Using flow cytometry, we determined ploidy levels of plants from natural populations along the Israeli gradient, spanning ∼424 km from mesic Mediterranean to extreme desert climates. In a common garden we recorded time of seedling emergence, flowering and senescence. We tested whether the proportion of allotetraploids in the populations and phenological traits were associated with aridity. Contrary to a previous study in the Western Mediterranean, we found no effect of aridity on the proportion of allotetraploids and diploids within populations. Interestingly, phenology was associated with aridity: time of emergence was later, while flowering and senescence were earlier in desert plants. Our results indicate that in the Eastern Mediterranean, adaptation of Brachypodium to aridity is mediated mainly by phenology, rather than ploidy level. Therefore, we suggest that genome duplication is not the main driver of adaptation to environmental stress; rather, phenological change as a drought escape mechanism may be the major adaptation.     

Leaving uncut refuges during meadow harvesting increases the functional diversity of Orthoptera

In the past, insect species richness was high in Central European seminatural grasslands, which were characterized by low‐intensity land use. Currently, however, the hay in most of these grasslands is mechanically harvested, which negatively impacts insect biodiversity. One way to reduce this negative effect is to leave unmown patches as refuges. In the current research we evaluated the short‐term effects of leaving an unmown patch on the taxonomic and functional diversity of the Orthoptera assemblage in a meadow. We found that orthopteran species richness and abundance were significantly reduced by mowing, whether or not a patch was left uncut. In contrast, functional evenness, indicating distribution of species abundances in a niche space, was reduced by mowing only if the plot lacked an uncut refuge. Functional richness, indicating the amount of niche space occupied by species, was elevated if the plot had an uncut refuge. Larger species were negatively affected by mowing, while habitat specialists, mobile species and soil‐ovipositing species benefitted from it. We infer that the presence of an uncut patch increased the diversity of habitats available to orthopterans and maintained even distribution of species among niche space. In summary, leaving an unmown refuge in grasslands could increase the functional diversity of orthopterans, even if it does not preserve taxonomic diversity.     

Climate change decreases the cooling effect from postfire albedo in boreal North America

Fire is a primary disturbance in boreal forests and generates both positive and negative climate forcings. The influence of fire on surface albedo is a predominantly negative forcing in boreal forests, and one of the strongest overall, due to increased snow exposure in the winter and spring months. Albedo forcings are spatially and temporally heterogeneous and depend on a variety of factors related to soils, topography, climate, land cover/vegetation type, successional dynamics, time since fire, season, and fire severity. However, how these variables interact to influence albedo is not well understood, and quantifying these relationships and predicting postfire albedo becomes increasingly important as the climate changes and management frameworks evolve to consider climate impacts. Here we developed a MODIS‐derived ‘blue sky’ albedo product and a novel machine learning modeling framework to predict fire‐driven changes in albedo under historical and future climate scenarios across boreal North America. Converted to radiative forcing (RF), we estimated that fires generate an annual mean cooling of ?1.77 ± 1.35 W/m² from albedo under historical climate conditions (1971–2000) integrated over 70 years postfire. Increasing postfire albedo along a south–north climatic gradient was offset by a nearly opposite gradient in solar insolation, such that large‐scale spatial patterns in RF were minimal. Our models suggest that climate change will lead to decreases in mean annual postfire albedo, and hence a decreasing strength of the negative RF, a trend dominated by decreased snow cover in spring months. Considering the range of future climate scenarios and model uncertainties, we estimate that for fires burning in the current era (2016) the cooling effect from long‐term postfire albedo will be reduced by 15%–28% due to climate change.     

Xylosandrus germanus in Central Europe: Spread into and within the Czech Republic

Invasive organisms represent great threats to ecosystems and great challenges to forest management. In Europe, the black timber bark beetle (Xylosandrus germanus) is an invasive secondary pest that mostly attacks the logs of felled trees. We showed the invasion history for Europe and using many local surveys, we summarize the current distribution and other available information on X. germanus in the Czech Republic. We report that this species is distributed from the lowlands to the mountains in the Czech Republic; it is widespread in the eastern half of the country, where it is more abundant in the warmer south and southeast areas than in the cooler areas. Most (78%) of the known localities are at elevation below 400 m a.s.l. Although an ice storm greatly increased X. germanus abundance near the border with Austria, its high abundance did not result in damage to standing trees. Presence of X. germanus in the Czech Republic for over 10 years has not led to heavy tree infestation.