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81.
Background
According to Regulation (EU) No 619/2011, trace amounts of non-authorised genetically modified organisms (GMO) in feed are tolerated within the EU if certain prerequisites are met. Tolerable traces must not exceed the so-called ‘minimum required performance limit’ (MRPL), which was defined according to the mentioned regulation to correspond to 0.1% mass fraction per ingredient. Therefore, not yet authorised GMO (and some GMO whose approvals have expired) have to be quantified at very low level following the qualitative detection in genomic DNA extracted from feed samples. As the results of quantitative analysis can imply severe legal and financial consequences for producers or distributors of feed, the quantification results need to be utterly reliable.Results
We developed a statistical approach to investigate the experimental measurement variability within one 96-well PCR plate. This approach visualises the frequency distribution as zygosity-corrected relative content of genetically modified material resulting from different combinations of transgene and reference gene Cq values. One application of it is the simulation of the consequences of varying parameters on measurement results. Parameters could be for example replicate numbers or baseline and threshold settings, measurement results could be for example median (class) and relative standard deviation (RSD). All calculations can be done using the built-in functions of Excel without any need for programming. The developed Excel spreadsheets are available (see section ‘Availability of supporting data’ for details). In most cases, the combination of four PCR replicates for each of the two DNA isolations already resulted in a relative standard deviation of 15% or less.Conclusions
The aims of the study are scientifically based suggestions for minimisation of uncertainty of measurement especially in —but not limited to— the field of GMO quantification at low concentration levels. Four PCR replicates for each of the two DNA isolations seem to be a reasonable minimum number to narrow down the possible spread of results.Electronic supplementary material
The online version of this article (doi:10.1186/s12859-014-0407-x) contains supplementary material, which is available to authorized users. 相似文献82.
The solution structure of Fe(II) cytochrome c551 from Pseudomonas aeruginosa based on 2D 1H NMR data is reported. Two sets of structure calculations were completed with a combination of simulated annealing and distance geometry calculations: one set of 20 structures included the heme-peptide covalent linkages, and one set of 10 structures excluded them. The main-chain atoms were well constrained within the two structural ensembles (1.30 and 1.35 A average RMSD, respectively) except for two regions spanning residues 30-40 and 60-70. The results were essentially the same when global fold comparisons were made between the ensembles with an average RMSD of 1.33 A. In total, 556 constraints were used, including 479 NOEs, 53 volume constraints, and 24 other distances. This report represents the first solution structure determination of a heme protein by 2D 1H NMR and should provide a basis for the application of these techniques to other proteins containing large prosthetic groups or cofactors. 相似文献
83.
Keyes WM Pecoraro M Aranda V Vernersson-Lindahl E Li W Vogel H Guo X Garcia EL Michurina TV Enikolopov G Muthuswamy SK Mills AA 《Cell Stem Cell》2011,8(2):164-176
The p53 homolog p63 is essential for development, yet its role in cancer is not clear. We discovered that p63 deficiency evokes the tumor-suppressive mechanism of cellular senescence, causing a striking absence of stratified epithelia such as the skin. Here we identify the predominant p63 isoform, ΔNp63α, as a protein that bypasses oncogene-induced senescence to drive tumorigenesis in?vivo. Interestingly, bypass of senescence promotes stem-like proliferation and maintains survival of the keratin 15-positive stem cell population. Furthermore, we identify the chromatin-remodeling protein Lsh as a new target of ΔNp63α that is an essential mediator of senescence bypass. These findings indicate that ΔNp63α is an oncogene that cooperates with Ras to promote tumor-initiating stem-like proliferation and suggest that Lsh-mediated chromatin-remodeling events are critical to this process. 相似文献
84.
In their attempts to evade the host immune response, mammalian viruses have evolved a wide range of strategies. These include the expression and modification of various host cytokines and receptors. Understanding the mechanism of action of these virally encoded proteins will clearly deepen our insights into immunology. In the past few months several new virally encoded chemokines have been described which can modify both the host immune and antiviral response. Their manipulation of the cytokine structure-function relationship may also be useful in the development of reagents for treating immune and proliferative diseases. 相似文献
85.
86.
Climatic and landscape correlates for potential West Nile virus mosquito vectors in the Seattle region. 总被引:3,自引:0,他引:3
Heidi L Pecoraro Heather L Day Robert Reineke Nathan Stevens John C Withey John M Marzluff J Scott Meschke 《Journal of vector ecology》2007,32(1):22-28
Climatic and landscape patterns have been associated with both relative mosquito abundance and transmission of mosquito-borne illnesses in many parts of the world, especially warm and tropical climes. To determine if temperature, precipitation, or degree of urbanization were similarly important in the number of potential mosquito vectors for West Nile virus in the moderately temperate climate of western Washington, mosquitoes were collected using CDC carbon-dioxide/light traps set throughout the Seattle region during the summers of 2003 and 2004. The type and abundance of recovered species were compared to ecological correlates. Temperature and mosquito abundance were positively correlated, while precipitation was not strongly correlated with numbers of mosquitoes. Potential WNV mosquito vectors were most abundant in urban and suburban sites, including sites near communal roosts of American crows (Corvus brachyrhynchos). Exurban sites had the greatest vector species diversity, and Culex pipiens was the most abundant species throughout the region. 相似文献
87.
Epidemiological study on the assay of antibodies to anti-TORCH agents and to HBV in a group of mother/child pairs in Palermo 总被引:1,自引:0,他引:1
C Spanò A Fazzolari Nesci G Pecoraro A Perino A Gullotti S Patti M Mazara 《Bollettino della Società italiana di biologia sperimentale》1983,59(12):1896-1902
The TORCH group: toxoplasma, rubeola, cytomegalovirus (CMV), herpes virus hominis (HSV) and also the B-virus of hepatitis (HBV) determine congenital malformations in the newborns. For this reason, the Authors leaded an epidemiologic study testing with some antibodies (anti-TORCH and anti-HBV) the serum of groups of mother-newborn of the Obstetrical Clinic of Palermo. This study became manageable because now there are available high specific immunoenzymatic methods, for example ELISA, the passive haemoagglutination and the haemoagglutination-inhibition. In our people, high concentration of rubeola, HSV and CMV and very low concentration of toxoplasma and HBV are shown. The frequency of malformation is related with the subclinical infection. The Authors suggest to extend same investigation at an higher number of pregnant women to prevent these congenital malformations. 相似文献