3,027 research outputs found
The Core Histone-binding Region of the Murine Cytomegalovirus 89K Immediate Early Protein
The gene regulatory immediate early protein, pp89, of murine cytomegalovirus interacts with both DNA-associated and isolated histones in vitro. We characterized the histone-binding region of pp89 and its cellular localization during cell division to examine the possible interaction between pp89 and chromatin. pp89 expressed constitutively in cell line BALB/c 3T3 IE1 does not interact with condensed chromatin. As observed in infected cells, pp89 is localized within the nucleus of cells during interphase but spreads throughout the cell plasma following degradation of the nuclear membrane during early mitosis. In late telophase, pp89 is reorganized within the nucleus. Analysis of pp89 deletion mutants and of fragments generated by cleavage at pH 2·5 revealed that the regions responsible for association with histone are located between amino acids 71 and 415, and are not identical with the domain that shows homology to histone H2B or the highly acidic carboxy-terminal region. A potential gene-activating role of the high affinity of pp89 for isolated histones and the low affinity for DNA-associated histones is discussed
An acidic region of the 89K murine cytomegalovirus immediate early protein interacts with DNA
The product of the ie 1 gene, the regulatory immediate early protein pp89 of murine cytomegalovirus (MCMV), interacts with core histones, which can mediate the association of pp89 with DNA. We report the capacity of pp89 to interact directly with DNA in the absence of cellular proteins. After separation of proteins by SDS–PAGe, pp89 bound ds- and ssDNA, with a preference for ssDNA. Binding to specific DNA sequences in the MCMV genome was not detected. The DNA-binding region of pp89 was located to amino acids 438 to 534 by analysis of deletion mutants expressed as -galactosidase or TrpE fusion proteins. This region is identical to the highly acidic C-terminal region spanning amino acids 424 to 532. The human cytomegalovirus IE1 protein, which contains a similar extended C-terminal acidic region, does not react with DNA under the same experimental conditions
Impact of inundation regime on wild bee assemblages and associated bee–flower networks
International audienceAbstractWild bee assemblages on flood-prone meadows were compared with those on rarely inundated sites along the river Danube in easternmost Lower Austria. We sampled flower-visiting bees on 32 meadows from April to August 2016. Although we recorded more bee individuals on rarely inundated meadows, total bee species richness was higher on regularly flooded meadows and we observed a stronger differentiation diversity of bees among annually flooded meadows. Three network metrics derived from a bipartite plant–bee interaction matrix were unaffected by flooding regime. We conclude that extreme floods, which sporadically affect the investigated habitats, may have a devastating effect on wild bee populations, but communities quickly recover. This resilience surely depends on recolonization from the surrounding landscape, which emphasizes the need to consider community dynamics in highly variable floodplain areas not only locally, but on a landscape scale
Ochs, Donna Anna und Max im Wirtshausgarten. Zum dramatischen Kontext der ’Zitate’ in Bergs «Wozzeck» (ll, 4)
The 89,000-Mr murine cytomegalovirus immediate-early protein activates gene transcription
To study trans-activation of gene expression by murine cytomegalovirus (MCMV) immediate-early (IE) proteins, the IE coding region 1 (ie1), which encodes the 89,000-Mr IE phosphoprotein (pp89), was stably introduced into L cells. A cell line was selected and characterized that efficiently expressed the authentic viral protein. The pp89 that was constitutively expressed in L cells stimulated the expression of transfected recombinant constructs containing the bacterial chloramphenicol acetyltransferase (CAT) gene under the control of viral promoters. The regulatory function of the ie1 product was confirmed by transient expression assays in which MCMV IE genes were cotransfected into L cells together with recombinant constructs of the CAT gene. For CAT activation by the ie1 product, a promoter region was required, but there was no preferential activation of a herpes simplex virus type 1 delayed-early promoter. All plasmid constructs that contained the intact coding sequences for pp89 induced gene expression in trans. The MCMV enhancer region was not essential for the expression of a functional IE gene product, and testing of the cis-regulatory activity of the MCMV enhancer revealed a low activity in L cells. Another region transcribed at IE times of infection, IE coding region 2, was unable to induce CAT expression and also did not augment the functional activity of ie1 after cotransfection
Effect of hypoxia and hyperoxia on exercise performance in healthy individuals and in patients with pulmonary hypertension: A systematic review
Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension, exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange and, presumably, these limitations are more pronounced at altitude. In studies performed near sea level in healthy subjects as well as in patients with pulmonary hypertension (PH) maximal performance during progressive ramp exercise and endurance of submaximal constant load exercise were substantially enhanced by breathing oxygen-enriched air. Both in healthy individuals and in PH-patients these improvements were mediated by a better arterial, muscular and cerebral oxygenation along with a reduced sympathetic excitation, as suggested by the reduced heart rate and alveolar ventilation at submaximal isoloads, and an improved pulmonary gas exchange efficiency, especially in patients with PH. In summary, in healthy individuals and in patients with pulmonary hypertension, alterations in the inspiratory PO2 by exposure to hypobaric hypoxia or normobaric hyperoxia reduce or enhance exercise performance, respectively, by modifying oxygen delivery to the muscles and the brain, by effects on cardiovascular and respiratory control and by alterations in pulmonary gas exchange. The understanding of these physiologic mechanisms helps counselling individuals planning altitude or air travel and prescribing oxygen therapy to patients with pulmonary hypertension
- …