An O(n) invariant rank 1 convex function that is not polyconvex

An O(n) invariant nonnegative rank 1 convex function of linear growth is given that is not polyconvex. This answers a recent question [8, p. 182] and [5]. The polyconvex hull of the function is calculated explicitly if n = 2:

A hőmérséklet hatása a növényi RNS interferencia hatékonyságára = The effect of temperature on RNA interference in higher plants

A hőmérséklet hatása a növényi RNS interferencia hatékonyságára Programunk célja a növényi RNS interferencia (RNAi) rendszer hőmérsékletfüggésének vizsgálata volt. Igazoltuk, hogy a növényi RNAi rendszer egyes útvonalai erősen hőmérsékletfüggőek, így pl. a transzgén-, illetve vírus-indukálta RNAi válaszok alacsony hőmérsékleten alig működnek, míg normál hőmérsékleten ezek a rendszerek igen aktívak. Kimutattuk, hogy a transzgénekről, illetve vírusokról származó, az RNAi rendszer által generált rövid RNS-ek (siRNS-ek) szintje a hőmérséklet emelésével gyorsan nő. Ismert, hogy a növény-vírus kapcsolatok jelentős részében a tünetek alacsony hőmérsékleten erősek, míg magas hőmérsékleten gyengék. Igazoltuk, hogy ennek oka az, hogy a vírus-indukálta RNAi rendszer -a növények leghatékonyabb antivirális rendszere- hidegben alig működik, így a tünetek felerősödnek, a víruskártétel jelentős. Ugyanakkor melegben a hatékony RNAi rendszer tünetcsökkenéshez, vírusellenállósághoz vezet. A transzgénikus növények jelentős részénél a transzgénikus fenotípus a transzgén-indukálta RNAi rendszeren alapszik. Bizonyítottuk, hogy alacsony hőmérsékleten a transzgén-indukálta RNAi rendszeren alapuló transzgénikus fenotípusok, pl antiszensz gátlás, vírusellenállóság, elveszhetnek. Kimutattuk azt is, hogy megfelelő transzgén konstrukciók (fordított ismétlődést tartalmazó konstrukciók) használatával ez a veszély csökkenthető, azaz a transzgénikus fenotípusok alacsony hőmérsékleten is stabilak maradnak. | The effect of temperature on RNA interference in higher plants The aim of our project was to study the effect of temperature on efficiency of RNA interference (RNAi) system of higher plants. We have shown that certain plant RNAi pathways, as transgene- or virus- induced RNAi pathways are inhibited at low temperature, while these patways work efficiently at normal temperature. Indeed, the levels of RNAi generated transgene or virus derived short RNAs (siRNAs) are dramatically reduced at low temperature. Previously, it has been reported that in cold, viral infections of plants lead to strong symptoms and that outbreaks of viral diseases are frequent. By contrast, at high temperature the symptoms are masked, plants recover quickly. We show that viral symptoms are strong in cold because virus induced plant RNAi (the most important antiviral sytem of plants) is inefficient, whereas at high temperature the efficient RNAi can protect plants. Transgenic phenotypes of many transgenic plants are depend on transgene induced RNAi. We have demonstrated that in cold, transgenic phenotypes -as antisense inactivation or virus resistance- that depend on trangene induced RNAi are dramatically weakened. Importantly, if inverted repeat containing constructs are used, trangenic phenotypes are stable even at low temperature

Növényi RNS degradációs rendszerek: a nonsense-mediated decay rendszer molekuláris biológiája = RNA degradation systems in plants: the molecular biology of nonsense-mediated decay system

A program célja a növényi Nonsense-mediated mRNA decay (NMD) rendszer molekuláris biológiájának megismerése volt. Az NMD egy ősi eukarióta minőségbiztosítási rendszer, amely felismeri és lebontja a korai stop kodonokat (PTC) tartalmazó mRNS-eket, ezáltal megelőzi a csonka, domináns-negatív mutáns fehérjék képződését. A program során kimutattuk, hogy a növényi NMD rendszer PTC-ként ismer fel minden stop kodont, amely utána 3'UTR régió szokatlanul hosszú, vagy ahol a 3'UTR-ban intron található. Azonosítottuk a növényi NMD rendszer 6 transz faktorát, és kimutattuk, hogy a kétféle NMD cisz elem felismerés csak részben átfedő génkészletet igényel. Igazoltuk, hogy a PTC tartalmú növényi transzkriptek kétféle úton bomolhatnak le, az SMG-7, illetve a UPF1 irányította útvonalon. Kimutattuk, hogy az utóbbi XRN4 5'-3' exonukleázt igényel. Munkánk során bizonyítottuk, hogy a növényi NMD autoregulált, az SMG-7 NMD faktort az NMD negatívan regulálja. Végül eredményeink alapján egy új eukarióta NMD evolúciós modellt dolgoztunk ki. | The aim of this project was to understand the molecular basis of plant Nonsense-mediated mRNA decay (NMD) system. NMD is an ancient eukaryotic quality control system that identifies and degrades mRNAs containing premature termination codons (PTC), thereby preventing the accumulation of truncated dominant-negative mutant proteins. During this project we have shown that plant NMD system identifies any stop codon as a PTC if the 3'UTR is unusually long or if the 3' UTR contains an intron. We have identified 6 NMD trans factors and shown that the two NMD cis elements identification system requires overlapping but not identical gene sets. We have demonstrated that PTC containing mRNAs can be degraded by two pathways, one is mediated by SMG-7 and another is controlled by UPF1. XRN4 exonuclease is required only for the UPF1 mediated pathway. We have shown that plant NMD is an autoregulated system as SMG-7 NMD trans factor is negatively regulated by NMD. Finally, we have elaborated a new model for the evolution of eukaryotic NMD systems

A mutant Escherichia coli that attaches peptidoglycan to lipopolysaccharide and displays cell wall on its surface

The lipopolysaccharide (LPS) forms the surface-exposed leaflet of the outer membrane (OM) of Gram-negative bacteria, an organelle that shields the underlying peptidoglycan (PG) cell wall. Both LPS and PG are essential cell envelope components that are synthesized independently and assembled by dedicated transenvelope multiprotein complexes. We have identified a point-mutation in the gene for O-antigen ligase (WaaL) in Escherichia coli that causes LPS to be modified with PG subunits, intersecting these two pathways. Synthesis of the PG-modified LPS (LPS*) requires ready access to the small PG precursor pool but does not weaken cell wall integrity, challenging models of precursor sequestration at PG assembly machinery. LPS* is efficiently transported to the cell surface without impairing OM function. Because LPS* contains the canonical vancomycin binding site, these surface-exposed molecules confer increased vancomycin-resistance by functioning as molecular decoys that titrate the antibiotic away from its intracellular target. This unexpected LPS glycosylation fuses two potent pathogen-associated molecular patterns (PAMPs). DOI: http://dx.doi.org/10.7554/eLife.05334.00

Generation of Simulation Based Operational Database for an Acid Gas Removal Plant with Automatic Calculations

Computer aided process design is improving with newer and newer tools. One of such tools is the automatic calculation technique that enables the combination of different software tools to enhance the efficiency of the calculations. In our research work Aspen HYSYS model of a petrochemical plant is built in order to simulate responses of an existing plant to the changes in the composition and amount of feed material. The Aspen HYSYS is connected to Microsoft Excel program; simu-lated operational data are stored in an operational database and transported to Excel for further analysis. The automatic calculation completed with the two software tools mutually strengthens their merits and results in enhanced insight into the operational features of any plant. Comparison of the projected input parameters of the petrochemical plant studied shows that the extension of the plant is badly needed. Cash-flow analysis suggests that the extension is profitable

The bacterial cell envelope as delimiter of anti-infective bioavailability - An in vitro permeation model of the Gram-negative bacterial inner membrane.

Gram-negative bacteria possess a unique and complex cell envelope, composed of an inner and outer membrane separated by an intermediate cell wall-containing periplasm. This tripartite structure acts intrinsically as a significant biological barrier, often limiting the permeation of anti-infectives, and so preventing such drugs from reaching their target. Furthermore, identification of the specific permeation-limiting envelope component proves difficult in the case of many anti-infectives, due to the challenges associated with isolation of individual cell envelope structures in bacterial culture. The development of an in vitro permeation model of the Gram-negative inner membrane, prepared by repeated coating of physiologically-relevant phospholipids on Transwell(®) filter inserts, is therefore reported, as a first step in the development of an overall cell envelope model. Characterization and permeability investigations of model compounds as well as anti-infectives confirmed the suitability of the model for quantitative and kinetically-resolved permeability assessment, and additionally confirmed the importance of employing bacteria-specific base materials for more accurate mimicking of the inner membrane lipid composition - both advantages compared to the majority of existing in vitro approaches. Additional incorporation of further elements of the Gram-negative bacterial cell envelope could ultimately facilitate model application as a screening tool in anti-infective drug discovery or formulation development