Aptamerek - az antitestek lehetséges alternatívái

Az anitesteken alapuló eljárások számos különböző szerkezeté élelmiszerszennyező szelektív kimutatását teszik lehetővé. Az ellenanyagok szélesköré alkalmazásának alternatíváját jelenthetik az ún. aptamerek, amelyek jól kötődhetnek számos különféle molekulához. A SELEX eljárás elméleti lehetőséget teremt nagy számú aptamer gyors és költséghatékony elåállítására. Az aptamer-célmolekula kölcsönhatás számos analitikai kimutatási módszer alapjául szolgálhat. Mindezek alapján jogosan feltételezhetå, hogy a napjainkban rutinszeréen alkalmazott antitesteken alapuló kimutatási módszerek mellet, illetve helyett a közeli jövåben megjelenhetnek az aptamer alapú élelmiszervizsgálati módszerek is. Methods based on antibodies provide the possibility for the selective identification of many food containants. The so-called aptamers well combined to different molecules could be the alternative. The SELEX procedure provides a theoretical possibility for a rush and cost- efficient production of many aptamers. The interaction between aptamer and molecule can be the basic for many analytical identification methods. In consideration of all that statuments it can be assumed that beside or instead of identification routine methods on the basic of antibodies also food investigation methods on the basic of aptamers will be avaible in the next future

Graph sharing games: complexity and connectivity

We study the following combinatorial game played by two players, Alice and Bob, which generalizes the Pizza game considered by Brown, Winkler and others. Given a connected graph G with nonnegative weights assigned to its vertices, the players alternately take one vertex of G in each turn. The first turn is Alice's. The vertices are to be taken according to one (or both) of the following two rules: (T) the subgraph of G induced by the taken vertices is connected during the whole game, (R) the subgraph of G induced by the remaining vertices is connected during the whole game. We show that if rules (T) and/or (R) are required then for every epsilon > 0 and for every positive integer k there is a k-connected graph G for which Bob has a strategy to obtain (1-epsilon) of the total weight of the vertices. This contrasts with the original Pizza game played on a cycle, where Alice is known to have a strategy to obtain 4/9 of the total weight. We show that the problem of deciding whether Alice has a winning strategy (i.e., a strategy to obtain more than half of the total weight) is PSPACE-complete if condition (R) or both conditions (T) and (R) are required. We also consider a game played on connected graphs (without weights) where the first player who violates condition (T) or (R) loses the game. We show that deciding who has the winning strategy is PSPACE-complete.Comment: 22 pages, 11 figures; updated references, minor stylistical change

A set of ligation-independent in vitro translation vectors for eukaryotic protein production

<p>Abstract</p> <p>Background</p> <p>The last decade has brought the renaissance of protein studies and accelerated the development of high-throughput methods in all aspects of proteomics. Presently, most protein synthesis systems exploit the capacity of living cells to translate proteins, but their application is limited by several factors. A more flexible alternative protein production method is the cell-free in vitro protein translation. Currently available in vitro translation systems are suitable for high-throughput robotic protein production, fulfilling the requirements of proteomics studies. Wheat germ extract based in vitro translation system is likely the most promising method, since numerous eukaryotic proteins can be cost-efficiently synthesized in their native folded form. Although currently available vectors for wheat embryo in vitro translation systems ensure high productivity, they do not meet the requirements of state-of-the-art proteomics. Target genes have to be inserted using restriction endonucleases and the plasmids do not encode cleavable affinity purification tags.</p> <p>Results</p> <p>We designed four ligation independent cloning (LIC) vectors for wheat germ extract based in vitro protein translation. In these constructs, the RNA transcription is driven by T7 or SP6 phage polymerase and two TEV protease cleavable affinity tags can be added to aid protein purification. To evaluate our improved vectors, a plant mitogen activated protein kinase was cloned in all four constructs. Purification of this eukaryotic protein kinase demonstrated that all constructs functioned as intended: insertion of PCR fragment by LIC worked efficiently, affinity purification of translated proteins by GST-Sepharose or MagneHis particles resulted in high purity kinase, and the affinity tags could efficiently be removed under different reaction conditions. Furthermore, high in vitro kinase activity testified of proper folding of the purified protein.</p> <p>Conclusion</p> <p>Four newly designed in vitro translation vectors have been constructed which allow fast and parallel cloning and protein purification, thus representing useful molecular tools for high-throughput production of eukaryotic proteins.</p

Selection and Characterization of a Novel DNA Aptamer for Label-Free Fluorescence Biosensing of Ochratoxin A

Nucleic acid aptamers are emerging as useful molecular recognition tools for food safety monitoring. However, practical and technical challenges limit the number and diversity of available aptamer probes that can be incorporated into novel sensing schemes. This work describes the selection of novel DNA aptamers that bind to the important food contaminant ochratoxin A (OTA). Following 15 rounds of in vitro selection, sequences were analyzed for OTA binding. Two of the isolated aptamers demonstrated high affinity binding and selectivity to this mycotoxin compared to similar food adulterants. These sequences, as well as a truncated aptamer (minimal sequence required for binding), were incorporated into a SYBR® Green I fluorescence-based OTA biosensing scheme. This label-free detection platform is capable of rapid, selective, and sensitive OTA quantification with a limit of detection of 9 nM and linear quantification up to 100 nM

bZIP transcription factors repress the expression of wheat (Triticum aestivum L.) high molecular weight glutenin subunit genes in vegetative tissues

High molecular weight glutenin subunits (HMW GS) represent an important fraction of endosperm-specific seed-storage proteins that provide elasticity to bread dough. Previously, the second cis-regulatory module (CRM2) was found to be one of the most conserved part of HMW GS promoters, which indicated its pre-eminent role in their gene regulation. Here, we observed that deletion of CRM2 from the promoters of the Bx7 and By8 HMW GS genes increased the leakage of their transient expression in wheat leaf tissue. The effect of a VP1, an Myb and an antisense bZIP transcription factor (TF)-binding site, potentially involved in endosperm-specific regulation within CRM2, was then studied. The activity of a Bx7 gene promoter containing a mutant CRM2 with altered VP1 and Myb TF-binding sites, but an intact bZIP TF-binding site, was similarly low to that of the wild type in leaves. Transactivation analysis and EMSA indicated the binding of TFs TabZIP34 and TabZIP115 to the Skn-1 motif GTCAT in CRM2 and the repression of Bx7 and By8 HMW GS gene promoter activity in leaves. TabZIP34 and TabZIP115 may be involved in the downregulation of HMW GS gene expression in vegetative tissues and early-stage endosperm as well its modulation during seed maturation

Comparative analysis of atmospheric parameters from high-resolution spectroscopic sky surveys: APOGEE, GALAH, Gaia-ESO

SDSS-IV APOGEE-2, GALAH and Gaia-ESO are high resolution, ground-based, multi-object spectroscopic surveys providing fundamental stellar atmospheric parameters and multiple elemental abundance ratios for hundreds of thousands of stars of the Milky Way. We undertake a comparison between the most recent data releases of these surveys to investigate the accuracy and precision of derived parameters by placing the abundances on an absolute scale. We discuss the correlations in parameter and abundance differences as a function of main parameters. Uncovering the variants provides a basis to on-going efforts of future sky surveys. Quality samples from the APOGEE-GALAH, APOGEE-GES and GALAH-GES overlapping catalogs are collected. We investigate the mean variants between the surveys, and linear trends are also investigated. We compare the slope of correlations and mean differences with the reported uncertainties. The average and scatter of vrad, Teff, log g, [M/H] and vmicro, along with numerous species of elemental abundances in the combined catalogs show that in general there is a good agreement between the surveys. We find large radial velocity scatters ranging from 1.3 km/s to 4.4 km/s when comparing the three surveys. We observe weak trends: e.g. in $\Delta$Teff vs. $\Delta$log g for the APOGEE-GES stars, and a clear correlation in the vmicro-$\Delta$vmicro planes in the APOGEE-GALAH common sample. For [$\alpha$/H], [Ti/H] (APOGEE-GALAH giants) and [Al/H] (APOGEE-GALAH dwarfs) potential strong correlations are discovered as a function of the differences in the main atmospheric parameters, and we find weak trends for other elements. In general we find good agreement between the three surveys within their respective uncertainties. However, there are certain regimes in which strong variants exist, which we discuss. There are still offsets larger than 0.1 dex in the absolute abundance scales.Comment: Accepted in A&A, 23 pages, 13 figures, 6 tables. A minor correction is applied to the Gaia-ESO Survey's solar reference: Grevesse et al. (2007) instead of Grevesse & Sauval (1998

Gráfok, geometria, véletlen, algoritmusok = Graphs, geometry, randomness, algorithms

Jelentős eredményeket értünk el a gráfelmélet, geometria, sztochasztika és algoritmusok kérdésköreiben, sokszor a területek közös elméletét gyarapítottuk. Kiemelünk néhány karakterisztikus eredményt: Hozzájárultunk annak megértéséhez ''hogyan viselkednek'' végtelen tranzitív gráfok minimális elvágó élhalmazai kvaziizometriák mellett (Babson és Benjamini két kérdésének megválaszolásával). Gráfokhoz rendeltünk egy geometria jellegű slope paramétert, amely különböző változatai több kutatást indítottak el. Gráfok pakolásainak központi megoldatlan kérdésével, az Bollobás-Eldridge-sejtéssel, kapcsolatban több részeredményt értünk el. Az OTKA résztvevői sok társszerzővel dolgoztak együtt. Az OTKA pályázat segítségévél született munkában társszerzőink között vannak: Pavel Valtr, Oded Schramm, Bezdek András, Yuval Peres, Bollobás Béla, Turán György, Jiri Matousek, Alexandr Kostochka, T. Sós Vera a témaköreink nemzetközileg elismert nagyságai. A szegedi kombinatorika szeminárium munkája a kutatás mellett a fiatal diákok érdeklődését is felkelti. Szakdolgozatok mellett két phd értekezés is születendőben van és további phd hallgatók kutatnak kombinatorika témában. A szeminárium honlapja: http://www.math.u-szeged.hu/~hajnal/seminars/kombszem/kombszem.htm | We have achieved several important results in graph theory, geometry, probability theory and algorithm theory, often connecting these central fields. We underline a few characteristic results. We contributed to understanding how minimal cut sets in infinite transitive graphs are behaving under quasiisometries (we have answered two questions of Babson and Benjami). We have introduced and investigated the geometrical notion, the slope parameter of a graph. This notion motivated further research. We made major steps in the topics of graph packing, strongly related to the Bollobas-Eldridge conjecture. For example if H is a bipartite graph on n vertices, with maximal degree D, then for large enough n H is a spanning subgraph of G a graph on n vertices with minimal degree at least D/(D+1). Our participants worked with several co-authors, among others, with Pavel Valtr, Oded Schramm, Andras Bezdek, Yuval Peres, Bela Bollobas, Gyorgy Turan, Jiri Matousek, Alexandr Kostocka, Vera T. Sos. The Combinatorics Seminar in Szeged is not only a research center, but it plays important role in education. Several students have written their diploma thesis in combinatorics, two phd dissertations is about to be submitted and other phd students are working strongly connected to our seminar. The homepage of the seminar is http://www.math.u-szeged.hu/~hajnal/seminars/kombszem/kombszem.ht