Variations and trends of birch pollen seasons during 15 years (1996–2010) in relation to weather conditions in Poznań (western Poland)

Birch (Betula) pollen seasons were examined in relation to meteorological conditions in Poznań (1996–2010). Birch pollen grains were collected using a volumetric spore trap. An alternate biennial cycle of birch pollen season intensity was noticed in Poznań. The main factors influencing birch pollen season intensity were average daily minimum temperatures during the second fortnight of May and the month of June one year before pollination as well as the intensity of the pollen season of the previous year. Most of the pollen grains are recorded during the first week of the season; the number of pollen grains recorded at this time is positively correlated with mean maximum temperature and negatively correlated with daily rainfall. The significant effect of rainfall in reducing the season pollen index was noticed only during weak pollen seasons (season pollen index <?mean). In addition, mean daily maximum temperature during the first two weeks of the birch pollen season markedly influences its duration. No significant trends in duration and intensity of the pollen season were recorded, however, a slight tendency towards early pollination was observed (?0.4 days/year, p?=?0.310).     

Auxin and chloroplast movements

Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin‐mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p‐chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF^TIR1‐Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF^TIR1‐Aux/IAA‐ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins.     

Ecological validity of social interaction tests in rats and mice

Different rat and mouse models are used in studies of social interactions. Simple behavioral measures, which are commonly used in the laboratory, allow to perform relatively short experiments and to use multiple brain manipulation techniques. However, too much focus on the simplest behavioral models generates a serious risk of reducing ecological validity or even studying phenomena which would never happen outside of the laboratory. In this review, we discuss the suitability of mice and rats as model organisms for studying social behaviors, with focus on social transmission of fear paradigms. First, we briefly introduce the concept of domestication and what impact it had on laboratory rodents. Then, we present two aspects of social behaviors, sociability and dominance, which are crucial for social organization in these species. Finally, we present experimental models used for studying how animals transmit information about danger between each other, and how these models may reflect what happens in the natural environment. We discuss the difficulties that arise from our limited knowledge of rat and mouse ecology, especially their social life. We also explore the subject of balancing ecological validity and controllability in rodent models of social behaviors, the latter being particularly important for studying brain activity. Although it is very challenging, an efficient program for social neuroscience research should, in our opinion, aim at bridging the gap between laboratory and field studies.     

Fibroblast-like synoviocytes from rheumatoid arthritis patients express functional IL-15 receptor complex: endogenous IL-15 in autocrine fashion enhances cell proliferation and expression of Bcl-x(L) and Bcl-2

The hallmarks of rheumatoid arthritis (RA) are leukocytic infiltration of the synovium and expansiveness of fibroblast-like synoviocytes (FLS). The abnormal proliferation of FLS and their resistance to apoptosis is mediated, at least in part, by present in RA joints proinflammatory cytokines and growth factors. Because IL-15 exerts properties of antiapoptotic and growth factors, and is produced by RA FLS, we hypothesized that IL-15 participates in RA FLS activation. To test this hypothesis, we first examined whether RA FLS express chains required for high affinity functional IL-15R. Indeed, RA FLS express IL-15Ralpha at mRNA and protein levels. Moreover, we confirmed the presence of IL-2Rbeta and common gamma-chains. Interestingly, TNF-alpha or IL-1beta triggered significant elevation of IL-15Ralpha chain at mRNA and protein levels. Next, we investigated the effects of exogenous or endogenous IL-15 on Bcl-2 and Bcl-x(L) expression, FLS proliferation, and apoptosis. Exogenous IL-15 enhanced RA FLS proliferation and increased the level of mRNA-encoding Bcl-x(L). To test the role of endogenous IL-15 in the activation of RA FLS, an IL-15 mutant/Fcgamma2a protein exerting properties of specific antagonist to the IL-15Ralpha chain was used. We found that blocking IL-15 biological activities using this protein substantially reduced endogenous expression of Bcl-2 and Bcl-x(L), and RA FLS proliferation that was reflected by increased apoptosis. Thus, we have demonstrated that a distinctive phenotype of RA FLS, i.e., persistent activation, proliferation, and resistance to apoptosis, is related to the autocrine activation of IL-15Rs by FLS-derived IL-15.     

Ultrastructural studies of epidermis keratinization in grass snake embryos Natrix natrix L. (Lepidosauria, Serpentes) during late embryogenesis

The changes and biochemical features of the epidermis that accompany the differentiation and embryonic shedding complex formation in grass snake Natrix natrix L. embryos were studied ultrastructurally and immunocytochemically with two panels of antibodies (AE1, AE3, AE1/AE3; anti-cytokeratin, pan mixture, Lu-5 and PCK-26). All observed changes in the ultrastructure of the cells forming the epidermal layers were associated with the physiological changes that occurred in the embryonic epidermis, such as changing of the manner of nutrition and keratinization leading to the embryonic shedding complex formation. The layers that originated first (basal, outer and inner periderm and clear layer) differentiated very early and rapidly. Rapid differentiation was also observed in the layers that are very important for the functioning of the epidermis in Natrix embryos (oberhäutchen and beta-layers). They started to differentiate at developmental stage IX, and then fused and formed the embryonic shedding complex at developmental stage XI. During the embryonic development of the grass snake the smallest changes appeared in the ultrastructure of the cells in the mesos and alpha-layers because they perform supplementary functions in the process of embryonic molting. They were undifferentiated until the end of embryonic development and started to differentiate just before the first adult molting. AE1/AE3, anti-cytokeratin, pan mixture, Lu-5 and PCK-26 antibodies immunolabeled clear layer, oberhäutchen and beta-layers at the latest phase of developmental stage XI. It should be noted that these antibodies did not immunolabel the alpha-layer until hatching. The presence of alpha-keratin immunolabeling in layers that were keratinized, particularly in the oberhäutchen and beta-layers in embryos, indicated that they were not as hard as in fully mature individuals.     

Homocysteine thiolactone and <Emphasis Type="Italic">N</Emphasis>-homocysteinylated protein induce pro-atherogenic changes in gene expression in human vascular endothelial cells

Genetic or nutritional deficiencies in homocysteine (Hcy) metabolism lead to hyperhomocysteinemia (HHcy) and cause endothelial dysfunction, a hallmark of atherosclerosis. In addition to Hcy, related metabolites accumulate in HHcy but their role in endothelial dysfunction is unknown. Here, we examine how Hcy-thiolactone, N-Hcy-protein, and Hcy affect gene expression and molecular pathways in human umbilical vein endothelial cells. We used microarray technology, real-time quantitative polymerase chain reaction, and bioinformatic analysis with PANTHER, DAVID, and Ingenuity Pathway Analysis (IPA) resources. We identified 47, 113, and 30 mRNAs regulated by N-Hcy-protein, Hcy-thiolactone, and Hcy, respectively, and found that each metabolite induced a unique pattern of gene expression. Top molecular pathways affected by Hcy-thiolactone were chromatin organization, one-carbon metabolism, and lipid-related processes [?log(P value) = 20–31]. Top pathways affected by N-Hcy-protein and Hcy were blood coagulation, sulfur amino acid metabolism, and lipid metabolism [?log(P value)] = 4–11; also affected by Hcy-thiolactone, [?log(P value) = 8–14]. Top disease related to Hcy-thiolactone, N-Hcy-protein, and Hcy was ‘atherosclerosis, coronary heart disease’ [?log(P value) = 9–16]. Top-scored biological networks affected by Hcy-thiolactone (score = 34–40) were cardiovascular disease and function; those affected by N-Hcy-protein (score = 24–35) were ‘small molecule biochemistry, neurological disease,’ and ‘cardiovascular system development and function’; and those affected by Hcy (score = 25–37) were ‘amino acid metabolism, lipid metabolism,’ ‘cellular movement, and cardiovascular and nervous system development and function.’ These results indicate that each Hcy metabolite uniquely modulates gene expression in pathways important for vascular homeostasis and identify new genes and pathways that are linked to HHcy-induced endothelial dysfunction and vascular disease.     

Enhancing solubilisation and methane production kinetic of switchgrass by microwave pretreatment

This study investigated the effects of microwave pretreatment of switchgrass in order to enhance its anaerobic digestibility. Response surface analysis was applied to screen the effects of temperature and time of microwave pretreatment on matter solubilisation. The composite design showed that only temperature had a significant effect on solubilisation level. Then the effects of the microwave pretreatment were correlated to the pretreatment temperature. The sCOD/tCOD ratio was equal to 9.4% at 90°C and increased until 13.8% at 180°C. The BMP assays of 42 days showed that microwave pretreatment induced no change on the ultimate volume of methane but had an interesting effect on the reaction kinetic. Indeed, the time required to reach 80% of ultimate volume CH(4) is reduced by 4.5 days at 150°C using the microwave pretreatment.     

Induction of adventitious shoot regeneration in chrysanthemum as affected by the season

The subject of investigation was Chrysanthemum x grandiflorum (Ramat.) Kitam., ‘Satinbleu’. Leaf explants and internodes were excised from the middle part of the donor sterile plant. Two methods of explant inoculation were applied: explants were placed polarly and horizontally. Modified MS medium (Murashige and Skoog 1962), supplemented with 11.4 μM indoleacetic acid and 2.7 μM 6-benzylaminopurine, were prepared to induce adventitious bud formation. Four dates of explant inoculation on the medium were tested: January 15, April 15, July 15, and October 15. Thus, regeneration occurred in winter, spring, summer, and autumn. In the present study, a more intensive regeneration in ‘Satinbleu’ chrysanthemum was observed in summer and autumn than in spring and winter, irrespective of the kind of explant and the inoculation method.