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301.
302.
Mycobacterium avium subsp. hominissuis is an opportunistic pathogen that is associated with biofilm-related infections of the respiratory tract and is difficult to treat. In recent years, extracellular DNA (eDNA) has been found to be a major component of bacterial biofilms, including many pathogens involved in biofilm-associated infections. To date, eDNA has not been described as a component of mycobacterial biofilms. In this study, we identified and characterized eDNA in a high biofilm-producing strain of Mycobacterium avium subsp. hominissuis (MAH). In addition, we surveyed for presence of eDNA in various MAH strains and other nontuberculous mycobacteria. Biofilms of MAH A5 (high biofilm-producing strain) and MAH 104 (reference strain) were established at 22°C and 37°C on abiotic surfaces. Acellular biofilm matrix and supernatant from MAH A5 7 day-old biofilms both possess abundant eDNA, however very little eDNA was found in MAH 104 biofilms. A survey of MAH clinical isolates and other clinically relevant nontuberculous mycobacterial species revealed many species and strains that also produce eDNA. RAPD analysis demonstrated that eDNA resembles genomic DNA. Treatment with DNase I reduced the biomass of MAH A5 biofilms when added upon biofilm formation or to an already established biofilm both on abiotic surfaces and on top of human pharyngeal epithelial cells. Furthermore, co-treatment of an established biofilm with DNase 1 and either moxifloxacin or clarithromycin significantly increased the susceptibility of the bacteria within the biofilm to these clinically used antimicrobials. Collectively, our results describe an additional matrix component of mycobacterial biofilms and a potential new target to help treat biofilm-associated nontuberculous mycobacterial infections. 相似文献
303.
Shuang Xing Timothy C. Bonebrake Chin Cheung Tang Evan J. Pickett Wenda Cheng Sasha E. Greenspan Stephen E. Williams Brett R. Scheffers 《Ecology and evolution》2016,6(22):8062-8074
Morphology mediates the relationship between an organism's body temperature and its environment. Dark organisms, for example, tend to absorb heat more quickly than lighter individuals, which could influence their responses to temperature. Therefore, temperature‐related traits such as morphology may affect patterns of species abundance, richness, and community assembly across a broad range of spatial scales. In this study, we examined variation in color lightness and body size within butterfly communities across hot and cool habitats in the tropical woodland–rainforest ecosystems of northeast Queensland, Australia. Using thermal imaging, we documented the absorption of solar radiation relative to color lightness and wingspan and then built a phylogenetic tree based on available sequences to analyze the effects of habitat on these traits within a phylogenetic framework. In general, darker and larger individuals were more prevalent in cool, closed‐canopy rainforests than in immediately adjacent and hotter open woodlands. In addition, darker and larger butterflies preferred to be active in the shade and during crepuscular hours, while lighter and smaller butterflies were more active in the sun and midday hours—a pattern that held after correcting for phylogeny. Our ex situ experiment supported field observations that dark and large butterflies heated up faster than light and small butterflies under standardized environmental conditions. Our results show a thermal consequence of butterfly morphology across habitats and how environmental factors at a microhabitat scale may affect the distribution of species based on these traits. Furthermore, this study highlights how butterfly species might differentially respond to warming based on ecophysiological traits and how thermal refuges might emerge at microclimatic and habitat scales. 相似文献
304.
MR-tomography (MRT) was performed in 25 patients with aneurysms and in 11 with coarctation of the thoracic aorta. For investigations a device with a resistive magnet (the force of a field--0.23 T) was used simultaneously with ECG. MRT revealed all cases of aortic dissection (10 patients) and one case with a false-positive result. Oblique sections in the direction of the thoracic aorta were used to assess the state of the aortic arch branches. Comparison of MRT and x-ray computerized tomography has shown that the diagnostic value of both methods was almost equal, however MRT was a safer method and easier to use. MRT was shown to be a method of choice for diagnosis of aneurysms and coarctations of the thoracic aorta but cannot be a substitution for aortography. 相似文献
305.
Sasha N. Jenkins Ian S. Waite Adrian Blackburn Rebecca Husband Steven P. Rushton David C. Manning Anthony G. O’Donnell 《Antonie van Leeuwenhoek》2009,95(4):319-334
Palace Leas, a long-term experiment at Cockle Park Farm, Northumberland, UK was established in winter 1896–1897 since when
the 13 plots have received regular and virtually unchanged mineral fertiliser and farm yard manure inputs. Fertilisers have
had a profound impact on soil pH with the organically fertilised plots showing a significantly higher pH than those receiving
mineral fertiliser where ammonium sulphate has led to soil acidification. Here, we investigate the impact of organic and mineral
fertilisers on the actinobacterial community structure of these soils using terminal restriction fragment length polymorphism
(T-RFLP) and 16S rRNA gene analysis. To differentiate fertiliser effects from seasonal variation, soils were sampled three
times over one growing season between May and September 2004 and January 2005. Community profiles obtained using T-RFLP were
analysed using multivariate statistics to investigate the relationship between community structure, seasonality and fertiliser
management. Soil pH was shown to be the most significant edaphic factor influencing actinobacterial communities. Canonical
correspondence analysis, used to investigate the relationship between the 16S rRNA gene community profiles and the environmental
parameters, showed that actinobacterial communities also responded to soil water content with major changes evident over the
summer months between May and September. Quantitative PCR of the actinobacterial and fungal 16S and 18S rRNA genes, respectively
suggested that fungal rRNA gene copy numbers were negatively correlated (P = 0.0131) with increasing actinobacterial signals. A similar relationship (P = 0.000365) was also evident when fatty acid methyl esters indicative of actinobacterial biomass (10-methyloctadecanoic acid)
were compared with the amounts of fungal octadecadienoic acid (18:2ω9,12). These results show clearly that soil pH is a major
driver of change in actinobacterial communities and that genera such as Arthrobacter and Micrococcus are particularly abundant in soils receiving organic inputs whilst others such as Streptomyces, Acidimicrobium and Actinospica are more prevalent in acid soils. The importance of these findings in terms of fungal abundance and potential disease suppression
are discussed. 相似文献
306.
Morgan David Yannick Auclair Sasha R. X. Dall Frank Cézilly 《Proceedings. Biological sciences / The Royal Society》2013,280(1753)
Condition-dependence of male ornaments is thought to provide honest signals on which females can base their sexual choice for genetic quality. Recent studies show that condition-dependence patterns can vary within populations. Although long-term association is thought to promote honest signalling, no study has explored the influence of pairing context on the condition-dependence of male ornaments. In this study, we assessed the influence of natural variation in body condition on song rate in zebra finches (Taeniopygia guttata) in three different situations: during short and long encounters with an unfamiliar female, and within heterosexual mated pairs. We found consistent individual differences in male directed and undirected song rate. Moreover, body condition had a positive effect on song rate in paired males. However, male song rate was not influenced by body condition during short or long encounters with unfamiliar females. Song rate appears to be an unreliable signal of condition to prospective females as even poor-condition birds can cheat and sing at a high rate. By contrast, paired females can reliably use song rate to assess their mate''s body condition, and possibly the genetic quality. We propose that species'' characteristics, such as mating system, should be systematically taken into account to generate relevant hypotheses about the evolution of condition-dependent male ornaments. 相似文献
307.
Deborah S. Bower Laura A. Brannelly Cait A. McDonald Rebecca J. Webb Sasha E. Greenspan Mathew Vickers Michael G. Gardner Matthew J. Greenlees 《Austral ecology》2019,44(3):433-448
A great diversity of parasites, from viruses and bacteria to a range of remarkable eukaryotic organisms, exploit reptile and amphibian hosts. Recent increases in the emergence of infectious disease have revealed the importance of understanding the effects of interactions between hosts and their parasites. Here we review the effects of parasite infection on a range of demographic, behavioural, genomic and physiological factors in reptile and amphibian species. Reviewing these parasite roles collectively, and prioritising areas for research, advances our ecological understanding and guides direction for conservation in a time of rapid species decline. Poorly resolved systems include Gymnophionan amphibians and Crocodilian hosts, in addition to viral and bacterial parasites. Future research should seek to understand processes enabling population recovery and examining synergistic interactions of parasites with fragmentation, climate change and other processes that threaten species persistence. 相似文献
308.
Profirovic J Han J Andreeva AV Neamu RF Pavlovic S Vogel SM Walter U Voyno-Yasenetskaya TA 《Journal of cellular physiology》2011,226(5):1255-1264
Vasodilator-stimulated phosphoprotein (VASP) is implicated in the protection of the endothelial barrier in vitro and in vivo. The function of VASP in thrombin signaling in the endothelial cells (ECs) is not known. For the first time we studied the effects of VASP deficiency on EC permeability and pulmonary vascular permeability in response to thrombin receptor stimulation. We provided the evidence that VASP deficiency potentiates the increase in endothelial permeability induced by activation of thrombin receptor in cultured human umbilical vein endothelial cells (HUVECs) and isolated mouse lungs. Using transendothelial resistance measurement, we showed that siRNA-mediated VASP downregulation in HUVECs leads to a potentiation of thrombin- and protease-activated receptor 1 (PAR-1) agonist-induced increase in endothelial permeability. Compared to control cells, VASP-deficient HUVECs had delayed endothelial junctional reassembly and abrogated VE-cadherin cytoskeletal anchoring in the recovery phase after thrombin stimulation, as demonstrated by immunofluorescence studies and cell fractionation analysis, respectively. Measurement of the capillary filtration coefficient in isolated mouse lungs demonstrated that VASP(-/-) mice have increased microvascular permeability in response to infusion with PAR-1 agonist compared to wild type mice. Lack of VASP led to decreased Rac1 activation both in VASP-deficient HUVECs after thrombin stimulation and VASP(-/-) mouse lungs after PAR-1 agonist infusion, indicating that VASP effects on thrombin signaling may be correlated with changes in Rac1 activity. This study demonstrates that VASP may play critical and complex role in the regulation of thrombin-dependent disruption of the endothelial barrier function. 相似文献
309.
310.