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81.
Peter J. Humphries Simone Linz Charles Semple 《Bulletin of mathematical biology》2013,75(10):1879-1890
Recently, we have shown that calculating the minimum–temporal-hybridization number for a set ${\mathcal{P}}$ of rooted binary phylogenetic trees is NP-hard and have characterized this minimum number when ${\mathcal{P}}$ consists of exactly two trees. In this paper, we give the first characterization of the problem for ${\mathcal{P}}$ being arbitrarily large. The characterization is in terms of cherries and the existence of a particular type of sequence. Furthermore, in an online appendix to the paper, we show that this new characterization can be used to show that computing the minimum–temporal hybridization number for two trees is fixed-parameter tractable. 相似文献
82.
Monika M. Lulsdorf Hai Ying Yuan Susan M. H. Slater Albert Vandenberg Xiumei Han L. Irina Zaharia Suzanne R. Abrams 《Plant Growth Regulation》2013,71(2):191-198
Cicer anatolicum, a perennial species, has ascochyta blight resistance superior to that found in the cultivated chickpea. However, hybridization barriers during early stages of embryo development curtail access to this trait. Since hormones play an essential role in early embryo development, we have determined the hormone profiles of 4-, 8-, and 12-day old seeds from a Canadian chickpea (Cicer arietinum L.) cv. CDC Xena, from Indian cvs. Swetha and Bharati, and from a perennial accession of C. anatolicum (PI 383626). Indole-3-acetic acid content peaked on day 4 in CDC Xena, on day 8 in both Indian cultivars but only on day 12 in C. anatolicum. The cytokinins, isopentenyladenosine (iPA) and trans zeatin riboside (tZR) were predominant in CDC Xena and Swetha seeds on day 4, whereas cis zeatin riboside was the major component in Bharati. In C. anatolicum, iPA maxed out on day 4 and tZR on day 12. The bioactive gibberellin GA1 spiked on day 4 in CDC Xena and Bharati, on day 8 in Swetha but only on day 12 in C. anatolicum. Eight-day old seeds had the highest abscisic acid content in the cultivars but spiked on day 12 in the perennial species. The hormone profiles of the perennial species showed delayed spikes in all four hormone groups indicating that there is a mismatch in the hormone requirements of the different embryos. Improving synchronization of early seed hormone profiles of cultivated and perennial chickpea should improve interspecific hybrid production. 相似文献
83.
Interspecies distances between propionic acid degraders and methanogens in syntrophic consortia for optimal hydrogen transfer 总被引:2,自引:0,他引:2
Monika Felchner-Zwirello Josef Winter Claudia Gallert 《Applied microbiology and biotechnology》2013,97(20):9193-9205
A mixed culture from an anaerobic biowaste digester was enriched on propionate and used to investigate interspecies hydrogen transfer in dependence of spatial distances between propionate degraders and methanogens. From 20.3 mM propionate, 20.8 mM acetate and 15.5 mM methane were formed. Maximum specific propionate oxidation and methane formation rates were 49 and 23 mmol?mg?1?day?1, respectively. Propionate oxidation was inhibited by only 20 mM acetate by about 50 %. Intermediate formate formation during inhibited methanogensis was observed. The spatial distribution and the biovolume fraction of propionate degraders and of methanogens in relation to the total population during aggregate formation were determined. Measurements of interbacterial distances were conducted with fluorescence in situ hybridization by application of group-specific 16S rRNA-targeted probes and 3D image analyses. With increasing incubation time, floc formation and growth up to 54 μm were observed. Propionate degraders and methanogens were distributed randomly in the flocs. The methanogenic biovolume fraction was high at the beginning and remained constant over 42 days, whereas the fraction of propionate degraders increased with time during propionate feeding. Interbacterial distances between propionate degraders and methanogens decreased with time from 5.30 to 0.29 μm, causing an increase of the maximum possible hydrogen flux from 1.1 to 10.3 nmol?ml?1?min?1. The maximum possible hydrogen flux was always higher than the hydrogen formation and consumption rate, indicating that reducing the interspecies distance by aggregation is advantageous in complex ecosystems. 相似文献
84.
Monika Primon Peter C. Huszthy Helena Motaln Krishna M. Talasila Ana Torkar Rolf Bjerkvig Tamara Lah Turnšek 《Experimental cell research》2013
Despite improved treatment options, glioblastoma multiforme (GBM) remains the most aggressive brain tumour with the shortest post-diagnostic survival. Arsenite (As2O3) is already being used in the treatment of acute promyelocytic leukaemia (APL), yet its effects on GBM have not been evaluated in detail. In U87MG cell monolayers, we have previously shown that arsenite cytotoxicity significantly increases upon transient inhibition of lysosomal protease Cathepsin L (CatL). As multicellular spheroids more closely represent in vivo tumours, we aimed to evaluate the impact of permanent CatL silencing on arsenite treatment in U87MG spheroids. CatL was stably silenced using shRNA expression plasmid packed lentiviruses. By using metabolic- and cell viability assays, we demonstrated that long-term CatL silencing significantly increased arsenite cytotoxicity in U87MG spheroids. Silenced CatL also increased arsenite-mediated apoptosis in spheroids via elevated p53 expression, Bax/Bcl2 ratio and caspase 3/7 activity, though with lower efficacy than in monolayers. Arsenite cytotoxicity was enhanced by lower CatL activity, since similar cytotoxicity increase was also observed using the novel CatL inhibitor AT094. The results have significant translational impact, since stable CatL silencing would enable the application of lower systemic doses of arsenite to achieve the desired cytotoxic effects on GBMs in vivo. 相似文献
85.
Marta Spodzieja Monika Rafalik Aneta Szymańska Aleksandra S. Kołodziejczyk Paulina Czaplewska 《Journal of molecular recognition : JMR》2013,26(9):415-425
Secondary amyloid A (AA) amyloidosis is an important complication of some chronic inflammatory diseases, primarily rheumatoid arthritis (RA). It is a serious, potentially life‐threatening disorder caused by the deposition of AA fibrils, which are derived from the circulatory, acute‐phase‐reactant, serum amyloid A protein (SAA). Recently, a specific interaction between SAA and the ubiquitous inhibitor of cysteine proteases—human cystatin C (hCC)—has been proved. Using a combination of selective proteolytic excision and high‐resolution mass spectrometry, the binding sites in the SAA and hCC sequences were assessed as SAA(86–104) and hCC(96–102), respectively. Here, we report further details concerning the hCC–SAA interaction. With the use of affinity tests and florescent ELISA‐like assays, the amino acid residues crucial for the protein interaction were determined. It was shown that all amino acid residues in the SAA sequence, essential for the formation of the protein complex, are basic ones, which suggests an electrostatic interaction character. The idea is corroborated by the fact that the most important residues in the hCC sequence are Ser‐98 and Tyr‐102; these residues are able to form hydrogen bonds via their hydroxyl groups. The molecular details of hCC–SAA complex formation might be helpful for the design of new compounds modulating the biological role of both proteins. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
86.
Magdalena Banas Katarzyna Zabieglo Gopinath Kasetty Monika Kapinska-Mrowiecka Julia Borowczyk Justyna Drukala Krzysztof Murzyn Brian A. Zabel Eugene C. Butcher Jens M. Schroeder Artur Schmidtchen Joanna Cichy 《PloS one》2013,8(3)
Chemerin, a chemoattractant ligand for chemokine-like receptor 1 (CMKLR1) is predicted to share similar tertiary structure with antibacterial cathelicidins. Recombinant chemerin has antimicrobial activity. Here we show that endogenous chemerin is abundant in human epidermis, and that inhibition of bacteria growth by exudates from organ cultures of primary human skin keratinocytes is largely chemerin-dependent. Using a panel of overlapping chemerin-derived synthetic peptides, we demonstrate that the antibacterial activity of chemerin is primarily mediated by Val66-Pro85, which causes direct bacterial lysis. Therefore, chemerin is an antimicrobial agent in human skin. 相似文献
87.
Xylene‐Bridged Phosphaviologen Oligomers and Polymers as High‐Performance Electrode‐Modifiers for Li‐Ion Batteries 下载免费PDF全文
Lithium‐ion batteries are one of the most common forms of energy storage devices used in society today. Due to the inherent limitations of conventional Li‐ion batteries, organic materials have surfaced as potentially suitable electrode alternatives with improved performance and sustainability. Viologens and phosphaviologens in particular, are strong electron‐accepting materials with excellent kinetic properties, making them suitable candidates for battery applications. In this paper, new polymeric species of the latter moieties are reported that lead to improved electrode stability and device performance. The performance of the phosphaviologen is further enhanced through the utilization of both redox steps, allowing for good performance proof‐of‐concept hybrid organic/Li‐ion batteries. This opens the potential for more sustainable and improved battery performance for use in current energy applications. 相似文献
88.
Volumetric hand‐held optoacoustic angiography as a tool for real‐time screening of dense breast 下载免费PDF全文
X. Luís Deán‐Ben Thomas F. Fehm Monika Gostic Daniel Razansky 《Journal of biophotonics》2016,9(3):253-259
Existing mammographic screening solutions are generally associated with several major drawbacks, such as exposure to ionizing radiation or insufficient sensitivity in younger populations with radiographically‐dense breast. Even when combined with ultrasound or magnetic resonance imaging, X‐Ray mammography may still attain unspecific or false positive results. Thus, development of new breast imaging tools represents a timely medical challenge. We report on a new approach to high‐resolution functional and anatomical breast angiography using volumetric hand‐held optoacoustic tomography, which employs light intensities safe for human use. Experiments in young healthy volunteers with fibroglandular‐dominated dense breasts revealed the feasibility of rendering three‐dimensional images representing vascular anatomy and functional blood oxygenation parameters at video rate. Sufficient contrast was achieved at depths beyond 2 cm within dense breasts without compromising the real‐time imaging performance. The suggested solution may thus find applicability as a standalone or supplemental screening tool for early detection and follow‐up of carcinomas in radiographically‐dense breasts.
89.
Ragnhildur?Einarsdottir Monika?Gibis Benjamin?Zeeb Kristberg?KristbergssonEmail authorView authors OrcID profile Jochen?Weiss 《Food biophysics》2016,11(4):417-428
Liposomes are a promising delivery system for bioactives in food and nutraceuticals. Their practical application is limited by their physical and chemical instability caused by extrinsic factors. The physical stability of liposomes of three different sizes coated with cold water fish skin gelatin was assessed during osmotic dehydration at 2, 21 and 70 °C. Soy lecithin was used to prepare 1 % liposomal dispersions. The size distribution was controlled with high pressure homogenization (1500 bar) and extrusion through polycarbonate membrane (3 and 0.8 μm). Fish gelatin was adsorbed to the interface to make secondary liposomes. Liposomal dispersions were osmotically dehydrated while monitoring the relative weight, size and rheological properties. The primary liposomes had an initial mean volume diameter (d4,3) of 0.09, 0.40 and 2.7 μm and a ζ-potential of ?55 mV. Secondary liposomes were 0.11, 0.45 and 3.4 μm with a ζ-potential of 25 mV. The size of liposomes influenced the stability of liposomes, with the smallest liposomes being stable for 30 min, corresponding to 80 % of the initial weight, while the larger liposomes were already aggregated. Secondary liposomes were stable to 120 min for the smaller liposomes and to 150 min for the largest liposomes corresponding to 40 % of the initial weight. Stability increased during dehydration at 2 °C. Coating the liposomes increased the physical stability of the liposomal dispersions at all temperatures. The results show that cold water fish skin gelatin is a viable option to coat liposomes of a wide size range. 相似文献
90.
Kerstin Büchel Trevor Fenning Jonathan Gershenzon Monika Hilker Torsten Meiners 《Phytochemistry Reviews》2016,15(5):961-983
Elms (Ulmus spp.) have long been appreciated for their environmental tolerance, landscape and ornamental value, and the quality of their wood. Although elm trees are extremely hardy against abiotic stresses such as wind and pollution, they are susceptible to attacks of biotic stressors. Over 100 phytopathogens and invertebrate pests are associated with elms: fungi, bacteria and insects like beetles and moths, and to a lesser extent aphids, mites, viruses and nematodes. While the biology of the pathogen and insect vector of the Dutch elm disease has been intensively studied, less attention has been paid so far to the defence mechanisms of elms to other biotic stressors. This review highlights knowledge of direct and indirect elm defences against biotic stressors focusing on morphological, chemical and gene regulation aspects. First, we report how morphological defence mechanisms via barrier formation and vessel occlusion prevent colonisation and spread of wood- and bark-inhabiting fungi and bacteria. Second, we outline how secondary metabolites such as terpenoids (volatile terpenoids, mansonones and triterpenoids) and phenolics (lignans, coumarins, flavonoids) in leaves and bark are involved in constitutive and induced chemical defence mechanisms of elms. Third, we address knowledge on how the molecular regulation of elm defence is orchestrated through the interaction of a huge variety of stress- and defence-related genes. We conclude by pointing to the gaps of knowledge on the chemical and molecular mechanisms of elm defence against pest insects and diseases. An in-depth understanding of defence mechanisms of elms will support the development of sustainable integrated management of pests and diseases attacking elms. 相似文献