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991.
Virginie Molinier Claude Murat Andri Baltensweiler Ulf Büntgen Francis Martin Barbara Meier Barbara Moser Ludger Sproll Ulrich Stobbe Willy Tegel Simon Egli Martina Peter 《Mycorrhiza》2016,26(8):895-907
Although the Burgundy truffle (Tuber aestivum) is an ectomycorrhizal fungus of important economic value, its subterranean life cycle and population biology are still poorly understood. Here, we determine mating type and simple sequence repeat (SSR) maternal genotypes of mapped fruiting bodies to assess their genetic structure within two naturally colonized forest sites in southern Germany. Forty-one genotypes were identified from 112 fruiting bodies. According to their mating types, the maternal genotypes were aggregated only in one population. Genotypic diversity of individuals that mostly were small and occurred in 1 out of 2 years of sampling was high. Although these results suggested a ruderal colonization strategy, some genets spread several hundred meters. This result indicates that, besides sexual spore dispersal, vegetative growth or spreading by mycelial propagules contributes to dissemination. In one site, fewer individuals with a tendency to expand genets belonging to only one genetic group were observed. In the second site, numerous small individuals were found and were grouped into two clearly differentiated genetic groups that were spatially intermingled. Forest characteristics and disturbances are possible reasons for the observed genetic patterns. Our findings contribute to a better understanding of the biology of one of the most widespread and commercially important truffle species. This knowledge is critical for establishing and maintaining sustainable long-term truffle cultivations. 相似文献
992.
The presence of eukaryotic parasites (i.e. chytridiomycetes and oomycetes) infecting benthic marine diatoms was revealed by a reconnaissance survey in the Solthörn tidal flat (southern North Sea, Germany) followed by 5 months of regular monitoring in order to assess the impact of these zoosporic fungal pathogens on microphytobenthic diatom communities. Additionally, variation of environmental factors such as sediment composition and nutrient concentrations were monitored. Pre-treatment of sediment samples using short ultrasound pulses and gradient centrifugation, in combination with CalcoFluor White, were used for the visualization of both pathogen groups. The highest prevalence of infected benthic diatoms was observed in late September (6.3% of the total benthic diatom community), correlating with the highest abundance of benthic diatoms recorded during the survey (6.5 ± 1.3 × 104 cells cm–2). Most infections were caused by chytrids (up to 99.8%) and, only in a few cases, by oomycetes. The analysis of individual host abundances/infection prevalence showed in most cases a decline in cell numbers of the host species with increasing numbers of the eukaryotic parasite. Several shifts in the diatom community composition were observed. Statistical analysis revealed that the abundance of the benthic diatom hosts and their parasites was related to seasonal variation in temperature, irradiance and nutrient availability, particularly of dissolved inorganic nitrogen. 相似文献
993.
The phylogenetic position of the extinct Cuban Macaw Ara tricolor based on complete mitochondrial genome sequences 下载免费PDF全文
The Cuban Macaw Ara tricolor was a species of macaw native to Cuba and Isla de la Juventud in the Caribbean that became extinct in the 1860s. Morphologically, it was similar to, but distinctively smaller than, the large red macaws – Scarlet Macaw Ara macao and Red‐and‐green Macaw Ara chloropterus. A close affinity with the Scarlet Macaw has been suggested based on plumage similarities. In this study we use complete mitochondrial genome sequences to examine the phylogenetic position of the Cuban Macaw. Our results do not indicate a sister‐species relationship with the Scarlet Macaw but place the Cuban Macaw as sister to the two red species and the two large green macaws, the Military Macaw Ara militaris and the Great Green Macaw Ara ambiguus. Divergence estimates suggests that the Cuban Macaw separated from this group approximately 4 million years ago. 相似文献
994.
Mercuric chloride and sodium selenite were separately administered to male rats in the drinking water or in a combination
(2.5 mmol Hg/L and 0.1 mmol Se/L). The mercuric chloride group showed histopathological lesions, as evidenced by cell necrosis
in the liver and tubular necrosis in the kidney. The sodium selenite group showed some depression in growth, but pathological
changes were found neither in the liver nor in the kidney. Simultaneous administration of both compounds produced a protective
effect on weight loss and histopathology. These effects were associated with some small structures in the kidney proximal
tubules and to some structure in the extracellular space in the liver. Thin, unstained cryosections were freeze-dried and
examined in the Studsvik Nuclear Microprobe. The structures observed in the liver and the kidney were shown to contain both
selenium and mercury. 相似文献
995.
Electron microscope tomography allows three-dimensional reconstruction of ultrastructural objects at the molecular level. The method is general and not limited to symmetric, or regularly ordered structures. Alone, or in combination with immunoelectron microscopy and electron spectroscopic imaging, electron microscope tomography is a powerful technique in cell and molecular biology. 相似文献
996.
Two loci encoding human U4 RNA, designated U4/7 and U4/14, have been isolated and sequenced. Both are pseudogenes in that their sequences do not match any identified human U4 RNA species perfectly. The U4/7 locus harbours a full-length pseudogene of 144 bp with eight base substitutions in the structural region. This pseudogene might be derived from a hitherto unidentified human U4 RNA gene. The second locus, U4/14, has a complex structure; the structural sequence of a U4 gene has apparently been integrated into an Alu sequence. 相似文献
997.
Ulf Persson Fredrik Montgomery ?ke Carlsson Bj?rn Lindgren Lennart Ahnfelt 《BMJ (Clinical research ed.)》1988,296(6615):99-102
Selection of a cost effective method of prophylaxis against infection for patients undergoing total joint replacement was shown to depend on the number of arthroplasties performed each year at individual hospitals. When 100 arthroplasties were performed each year the prophylactic use of systemic antibiotics minimised the total costs of the department—that is, the combined costs of prophylaxis and reoperation for deep sepsis. Some departments also used local antibiotic prophylaxis in the form of polymethylmethacrylate cement impregnated with gentamicin or a combination of systemic and local prophylaxis at almost as low a total cost and with comparable effect.Selection of a method of prophylaxis should not be determined solely on the basis of reducing costs. When a value was assigned to the effects of loss of health an economic optimum was established that allowed selection of a more costly method of prophylaxis together with further reductions in the incidence of infection and the need for reoperation. 相似文献
998.
Riccardo Di Guida Jasper Engel J. William Allwood Ralf J. M. Weber Martin R. Jones Ulf Sommer Mark R. Viant Warwick B. Dunn 《Metabolomics : Official journal of the Metabolomic Society》2016,12(5):93
Introduction
The generic metabolomics data processing workflow is constructed with a serial set of processes including peak picking, quality assurance, normalisation, missing value imputation, transformation and scaling. The combination of these processes should present the experimental data in an appropriate structure so to identify the biological changes in a valid and robust manner.Objectives
Currently, different researchers apply different data processing methods and no assessment of the permutations applied to UHPLC-MS datasets has been published. Here we wish to define the most appropriate data processing workflow.Methods
We assess the influence of normalisation, missing value imputation, transformation and scaling methods on univariate and multivariate analysis of UHPLC-MS datasets acquired for different mammalian samples.Results
Our studies have shown that once data are filtered, missing values are not correlated with m/z, retention time or response. Following an exhaustive evaluation, we recommend PQN normalisation with no missing value imputation and no transformation or scaling for univariate analysis. For PCA we recommend applying PQN normalisation with Random Forest missing value imputation, glog transformation and no scaling method. For PLS-DA we recommend PQN normalisation, KNN as the missing value imputation method, generalised logarithm transformation and no scaling. These recommendations are based on searching for the biologically important metabolite features independent of their measured abundance.Conclusion
The appropriate choice of normalisation, missing value imputation, transformation and scaling methods differs depending on the data analysis method and the choice of method is essential to maximise the biological derivations from UHPLC-MS datasets.999.
Natural killer (NK) cells belong to the innate immune system and protect against cancers and a variety of viruses including retroviruses by killing transformed or infected cells. They express activating and inhibitory receptors on their cell surface and often become activated after recognizing virus-infected cells. They have diverse antiviral effector functions like the release of cytotoxic granules, cytokine production and antibody dependent cellular cytotoxicity. The importance of NK cell activity in retroviral infections became evident due to the discovery of several viral strategies to escape recognition and elimination by NK cells. Mutational sequence polymorphisms as well as modulation of surface receptors and their ligands are mechanisms of the human immunodeficiency virus-1 to evade NK cell-mediated immune pressure. In Friend retrovirus infected mice the virus can manipulate molecular or cellular immune factors that in turn suppress the NK cell response. In this model NK cells lack cytokines for optimal activation and can be functionally suppressed by regulatory T cells. However, these inhibitory pathways can be overcome therapeutically to achieve full activation of NK cell responses and ultimately control dissemination of retroviral infection. One effective approach is to modulate the crosstalk between NK cells and dendritic cells, which produce NK cell-stimulating cytokines like type I interferons (IFN), IL-12, IL-15, and IL-18 upon retrovirus sensing or infection. Therapeutic administration of IFNα directly increases NK cell killing of retrovirus-infected cells. In addition, IL-2/anti-IL-2 complexes that direct IL-2 to NK cells have been shown to significantly improve control of retroviral infection by NK cells in vivo. In this review, we describe novel approaches to improve NK cell effector functions in retroviral infections. Immunotherapies that target NK cells of patients suffering from viral infections might be a promising treatment option for the future. 相似文献
1000.
Mike Fischer Baerbel Spies-Weisshart Karin Schrenk Bernd Gruhn Susan Wittig Anita Glaser Andreas Hochhaus Sebastian Scholl Ulf Schnetzke 《PloS one》2016,11(3)