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61.
What's in a name; Genetic structure in Solanum section Petota studied using population-genetic tools
Mirjam MJ Jacobs Marinus JM Smulders Ronald G van den Berg Ben Vosman 《BMC evolutionary biology》2011,11(1):42
Background
The taxonomy and systematic relationships among species of Solanum section Petota are complicated and the section seems overclassified. Many of the presumed (sub)species from South America are very similar and they are able to exchange genetic material. We applied a population genetic approach to evaluate support for subgroups within this material, using AFLP data. Our approach is based on the following assumptions: (i) accessions that may exchange genetic material can be analyzed as if they are part of one gene pool, and (ii) genetic differentiation among species is expected to be higher than within species. 相似文献62.
Susan C Burleigh Teun van de Laar Corné JM Stroop Wout MJ van Grunsven Niaobh O’Donoghue Pauline M Rudd Gavin P Davey 《BMC biotechnology》2011,11(1):1-17
Background
The photorespiratory nitrogen cycle in C3 plants involves an extensive diversion of carbon and nitrogen away from the direct pathways of assimilation. The liberated ammonia is re-assimilated, but up to 25% of the carbon may be released into the atmosphere as CO2. Because of the loss of CO2 and high energy costs, there has been considerable interest in attempts to decrease the flux through the cycle in C3 plants. Transgenic tobacco plants were generated that contained the genes gcl and hyi from E. coli encoding glyoxylate carboligase (EC 4.1.1.47) and hydroxypyruvate isomerase (EC 5.3.1.22) respectively, targeted to the peroxisomes. It was presumed that the two enzymes could work together and compete with the aminotransferases that convert glyoxylate to glycine, thus avoiding ammonia production in the photorespiratory nitrogen cycle.Results
When grown in ambient air, but not in elevated CO2, the transgenic tobacco lines had a distinctive phenotype of necrotic lesions on the leaves. Three of the six lines chosen for a detailed study contained single copies of the gcl gene, two contained single copies of both the gcl and hyi genes and one line contained multiple copies of both gcl and hyi genes. The gcl protein was detected in the five transgenic lines containing single copies of the gcl gene but hyi protein was not detected in any of the transgenic lines. The content of soluble amino acids including glycine and serine, was generally increased in the transgenic lines growing in air, when compared to the wild type. The content of soluble sugars, glucose, fructose and sucrose in the shoot was decreased in transgenic lines growing in air, consistent with decreased carbon assimilation.Conclusions
Tobacco plants have been generated that produce bacterial glyoxylate carboligase but not hydroxypyruvate isomerase. The transgenic plants exhibit a stress response when exposed to air, suggesting that some glyoxylate is diverted away from conversion to glycine in a deleterious short-circuit of the photorespiratory nitrogen cycle. This diversion in metabolism gave rise to increased concentrations of amino acids, in particular glutamine and asparagine in the leaves and a decrease of soluble sugars. 相似文献63.
Barbadocladius n. gen. is erected and described in larval, pupal and adult stages for two species: B. andinus sp. nov. and B. limay sp. nov., from Andean streams. The larva is distinctive by virtue of the very large ventromental 'beard' and the anterior parapods with a 'sleeve' of hooklets in addition to apical pectinate claws. The pupa has hooklets on some tergal and sternal intersegmental membranes. The adult, reported only in teneral specimens has hairy eyes, no antennal apical strong seta, no acrostichals, bare and unmarked wings, cylindrical 4th tarsomere subequal in length to the 5th, pulvilli about half the claw length, and hypopygium with anal point, lacking a virga. Molecular phylogenetic analysis eliminates relationships directly to the Eukiefferiella complex (which also have pupal hooklets), or to the Cricotopus group (adults also with hairy eyes), suggesting instead a sister group relationship to a suite of predominantly austral genera of Orthocladiinae. 相似文献
64.
Cranston ED Eita M Johansson E Netrval J Salajková M Arwin H Wågberg L 《Biomacromolecules》2011,12(4):961-969
The Young's modulus of multilayer films containing nanofibrillated cellulose (NFC) and polyethyleneimine (PEI) was determined using the strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) technique. (1) Multilayer films were built up on polydimethylsiloxane substrates using electrostatic layer-by-layer assembly. At 50% relative humidity, SIEBIMM gave a constant Young's modulus of 1.5 ± 0.2 GPa for 35-75 nm thick films. Conversely, in vacuum, the Young's modulus was 10 times larger, at 17.2 ± 1.2 GPa. A slight decrease in buckling wavelength with increasing strain was observed by scanning electron microscopy with in situ compression, and above 10% strain, extensive cracking parallel to the compressive direction occurred. We conclude that whereas PEI acts as a "glue" to hold multiple layers of NFC together, it prevents full development of hydrogen bonding and specific fibril-fibril interactions, and at high humidity, its hygroscopic nature decreases the elastic modulus when compared with pure NFC films. 相似文献
65.
Stoats are significant predators of native fauna in New Zealand. They occur in many habitat types and consume a wide range of prey. The diet of stoats in the Tasman River, South Canterbury, was studied by analysis of scats and den contents. Analysis of 206 scats showed that stoats ate mainly lagomorphs, birds and invertebrates. Minor components included mice, lizards, fish and hedgehogs. Stoats ate more birds in spring than in autumn, and female stoats ate more invertebrates than did males. The contents of 219 dens collected in the same area at the same time provided further information. Birds and lagomorphs occurred at high frequency in dens, and other components were minor. Remains in dens were larger than in scats and allowed identification of many more prey items to species level. Den contents revealed a potentially substantial impact of stoats on threatened shorebirds locally; this impact was not detected by analysis of scats. 相似文献
66.
Evans ME Hearn DJ Theiss KE Cranston K Holsinger KE Donoghue MJ 《The New phytologist》2011,191(2):555-563
Competing evolutionary forces shape plant breeding systems (e.g. inbreeding depression, reproductive assurance). Which of these forces prevails in a given population or species is predicted to depend upon such factors as life history, ecological conditions, and geographical context. Here, we examined two such predictions: that self-compatibility should be associated with the annual life history or extreme climatic conditions. We analyzed data from a clade of plants remarkable for variation in breeding system, life history and climatic conditions (Oenothera, sections Anogra and Kleinia, Onagraceae). We used a phylogenetic comparative approach and Bayesian or hybrid Bayesian tests to account for phylogenetic uncertainty. Geographic information system (GIS)-based climate data and ecological niche modeling allowed us to quantify climatic conditions. Breeding system and reproductive life span are not correlated in Anogra and Kleinia. Instead, self-compatibility is associated with the extremes of temperature in the coldest part of the year and precipitation in the driest part of the year. In the 60 yr since this pattern was anticipated, this is the first demonstration of a relationship between the evolution of self-compatibility and climatic extremes. We discuss possible explanations for this pattern and possible implications with respect to anthropogenic climate change. 相似文献
67.
Bayesian inference of phylogeny is unique among phylogenetic reconstruction methods in that it produces a posterior distribution of trees rather than a point estimate of the best tree. The most common way to summarize this distribution is to report the majority-rule consensus tree annotated with the marginal posterior probabilities of each partition. Reporting a single tree discards information contained in the full underlying distribution and reduces the Bayesian analysis to simply another method for finding a point estimate of the tree. Even when a point estimate of the phylogeny is desired, the majority-rule consensus tree is only one possible method, and there may be others that are more appropriate for the given data set and application. We present a method for summarizing the distribution of trees that is based on identifying agreement subtrees that are frequently present in the posterior distribution. This method provides fully resolved binary trees for subsets of taxa with high marginal posterior probability on the entire tree and includes additional information about the spread of the distribution. 相似文献
68.
T-helper 17 cell cytokines and interferon type I: partners in crime in systemic lupus erythematosus?
Zana Brkic Odilia BJ Corneth Cornelia G van Helden-Meeuwsen Radboud JEM Dolhain Naomi I Maria Sandra MJ Paulissen Nadine Davelaar Jan Piet van Hamburg Paul L van Daele Virgil A Dalm P Martin van Hagen Johanna MW Hazes Marjan A Versnel Erik Lubberts 《Arthritis research & therapy》2014,16(2):R62
Introduction
A hallmark of systemic autoimmune diseases like systemic lupus erythematosus (SLE) is the increased expression of interferon (IFN) type I inducible genes, so-called IFN type I signature. Recently, T-helper 17 subset (Th17 cells), which produces IL-17A, IL-17F, IL-21, and IL-22, has been implicated in SLE. As CCR6 enriches for Th17 cells, we used this approach to investigate whether CCR6+ memory T-helper cells producing IL-17A, IL-17F, IL-21, and/or IL-22 are increased in SLE patients and whether this increase is related to the presence of IFN type I signature.Methods
In total, 25 SLE patients and 15 healthy controls (HCs) were included. SLE patients were divided into IFN type I signature-positive (IFN+) (n = 16) and negative (IFN-) (n = 9) patients, as assessed by mRNA expression of IFN-inducible genes (IFIGs) in monocytes. Expression of IL-17A, IL-17F, IL-21, and IL-22 by CD4+CD45RO+CCR6+ T cells (CCR6+ cells) was measured with flow cytometry and compared between IFN+, IFN- patients and HCs.Results
Increased percentages of IL-17A and IL-17A/IL-17F double-producing CCR6+ cells were observed in IFN+ patients compared with IFN- patients and HCs. IL-17A and IL-17F expression within CCR6+ cells correlated significantly with IFIG expression. In addition, we found significant correlation between B-cell activating factor of the tumor necrosis family (BAFF)–a factor strongly correlating with IFN type I - and IL-21 producing CCR6+ cells.Conclusions
We show for the first time higher percentages of IL-17A and IL-17A/IL-17F double-producing CCR6+ memory T-helper cells in IFN+ SLE patients, supporting the hypothesis that IFN type I co-acts with Th17 cytokines in SLE pathogenesis. 相似文献69.
Kai Yu Zhang Angela E Kedgley Claire R Donoghue Daniel Rueckert Anthony MJ Bull 《Arthritis research & therapy》2014,16(1):R27
Introduction
The meniscus has an important role in force transmission across the knee, but a detailed three-dimensional (3D) morphometric shape analysis of the lateral meniscus to elucidate subject-specific function has not been conducted. The aim of this study was to perform 3D morphometric analyses of the lateral meniscus in order to correlate shape variables with anthropometric parameters, thereby gaining a better understanding of the relationship between lateral meniscus shape and its load-bearing function.Methods
The lateral meniscus (LM) was manually segmented from magnetic resonance images randomly selected from the Osteoarthritis Initiative (OAI) non-exposed control subcohort. A 3D statistical shape model (SSM) was constructed to extract the principal morphological variations (PMV) of the lateral meniscus for 50 subjects (25 male and 25 female). Correlations between the principal morphological variations and anthropometric parameters were tested. Anthropometric parameters that were selected included height, weight, body mass index (BMI), femoral condyle width and axial rotation.Results
The first principal morphological variation (PMV) was found to correlate with height (r = 0.569), weight (r = 0.647), BMI (r = 0.376), and femoral condyle width (r = 0.622). The third PMV was found to correlate with height (r = 0.406), weight (r = 0.312), and femoral condyle width (r = 0.331). The percentage of the tibial plateau covered by the lateral meniscus decreases as anthropometric parameters relating to size of the subject increase. Furthermore, when the size of the subject increases, the posterior and anterior horns become proportionally longer and wider.Conclusion
The correlations discovered suggest that variations in meniscal shape can be at least partially explained by the levels of loads transmitted across the knee on a regular basis. Additionally, as the size of the subject increases and body weight rises, the coverage percentage of the meniscus is reduced, suggesting that there would be an increase in the load-bearing by the cartilage. However, this reduced coverage percentage is compensated by the proportionally wider and longer meniscal horn. 相似文献70.
Nicola Richardson-Harman Craig W. Hendrix Namandjé N. Bumpus Christine Mauck Ross D. Cranston Kuo Yang Julie Elliott Karen Tanner Ian McGowan Angela Kashuba Peter A. Anton 《PloS one》2014,9(10)