Crazy-Clock Behavior and deterministic kinetic description of the Iodate-Arsenous Acid reaction

A jodát-arzénessav reakció számos „egzotikus” kémiai jelenség kísérleti demonstrálására alkalmas rendszer. A kinetikai leírást legtöbbször egy kétlépéses modellel hajtják végre, melyek a Dushman- és Roebuck-reakciókból áll. Külön érdekessége a rendszernek, hogy noha igen szélesköruen tanulmányozott, a bolondóra jellegu viselkedés (l. 3. oldal) elkerülte a kutatók figyelmét, mely pufferelt körülmények között is megfigyelheto. A jodát–arzénessav rendszerben pufferelt közegben, jodátfelesleg alkalmazása esetén bizonyítottuk a bolondóra viselkedést. A leírás érdekében 1290 független kinetikai mérést végeztünk el, kiegészítve a keverés hatékonyságának vizsgálatával egy modellrendszeren keresztül. A keverési sebesség szisztematikus változtatásával bizonyítottuk, hogy a hatékonyabb keverés hosszabb átlagos Landolt-idot eredményez. A keverés módjának változtatása azt bizonyította, hogy a reakció kimenetelének szempontjából az indítás pillanatában kialakuló inhomogenitások dönto fontosságúak, azonban a késobb fellépo keverési elégtelenségeket sem szabad elhanyagolnunk. A teljes oldattérfogat és a reaktor geometriája is jelentos hatással van a mért eloszlásgörbékre, a különbözo keveredések miatt. Bizonyítottuk azt a feltételezést, miszerint közel tökéletes kezdeti keverés esetén kis pH beállítása esetén a kinetikai görbék reprodukálhatóvá válnak, és stopped-flow idoskálára kerülnek. Az így nyert mérési eredményeket egy ötlépéses, egyszeru kinetikai modellel sikerült megillesztenünk, mely egyszerusége mellett megfeleloen leírja a rendszer fobb karakterisztikáját. Ez két, gyors eloegyensúlyt tartalmaz, továbbá egy, a jodát és az arzénessav között lejátszódó közvetlen reakciót. Ily módon az irodalomban széles körben elterjedt nézettel szemben a kezdeti jodidszennyezés nélkül is leírhatóvá válik a rendszer. A Roebuck-reakciót jellemzo kísérleti görbéket egy olyan kinetikai modellel sikerült leírnunk, amely elemi, vagy kvázi-elemi reakciósoron keresztül képes értelmezni a reakciót jellemzo jodid- és protoninhibíciót. A Dushman-reakció érzékeny az alkalmazott közegre, így a közegfüggo kinetikai paraméterek illesztését elvégeztük. A leíráshoz öt további kémiai reakciót vettünk figyelembe. Ezt követoen az összes (determinisztikus kinetikai) mérés illesztésével a két alrendszer és a jodát–arzénessav reakció leírását, 13 kémiai reakció figyelembevételével sikerült megoldanunk

A brasszinoszteroidok szerepének vizsgálata a növényi szervek morfogenezisének szabályozásában = The regulatory role of brassinosteroids in the morphogenic determination of plant organs

A brasszinoszteroidok (BR-ok) növényi szteroid hormonok, amelyek fontos szerepet játszanak az egyedfejlődési és reproduktív funkciók szabályozásában. Munkánk célja olyan tényezők azonosítása volt, amelyek a sejtek szenzitizálása, ill. a hormon felhalmozása révén befolyásolhatják a BR válaszreakciókat. Kimutattuk, hogy a feltételezett egyenletes kifejeződéssel szemben a BR receptort kódoló BRI1 gén differenciált szerv- és fejlődés-specifikus expressziót mutat. BRI1 promóter-riporter fúziókat hordozó transzgenikus Arabidopsis vonalainkban a fokozott hormonérzékenység szoros korrelációt mutatott a receptor erős kifejeződésével, jelezve a receptor sűrűség és a válaszreakció kialakulása közti kapcsolatot. Másrészt meghatároztuk az aktív BR formák korábban ismeretlen szintjét az Arabidopsis egyes szerveiben, igazolva, hogy a hormon felhalmozódás mértékét jórészt a bioszintetikus gének transzkripciós szintű szabályozása határozza meg. A sebesség-meghatározó CPD/CYP90A1 enzimről episztázis analízissel kimutattuk, hogy az a szintézis hatékonyságát közvetlenül a BR szintézis első reakcióját követően kontrollálja. Az anyagcsereút utolsó, még tisztázatlan enzim funkcióját karakterizálva meghatároztuk, hogy a CPD/CYP90A1 a szteroid váz C-3 pozíciójának oxidációjáért felelős. Ezzel egyúttal kísérletes bizonyítékot szolgáltattunk egy új, a korábban ismertnél hatékonyabb BR szintézisút in vivo jelentőségére. | Brassinosteroids (BRs) are steroidal plant hormones controlling morphogenesis and reproductive development. The aim of our project was to elucidate basic mechanisms that influence BR responses by modulating cellular susceptibility or accumulation of the biologically active hormone. We demonstrated that, in contrast to an earlier concept of ubiquitous expression, the BRI1 gene encoding the BR receptor shows differential organ-specific and developmental activity. Our BRI1 promoter-reporter constructs revealed that in Arabidopsis elevated BRI1 expression coincides with increased BR responsiveness, suggesting an important role for receptor abundance in the initiation of BR signaling. In a different approach we determined the hitherto unknown distribution of active BRs in the various organs of Arabidopsis, and provided evidence that the transcriptional control of BR biosynthetic genes efficiently regulates hormone accumulation. We have shown that CPD/CYP90A1 is a key enzyme of BR biosynthesis and, using epistasis analysis, we demonstrated that it controls intermediate flow immediately downstream of the first committed step of the BR pathway. Characterizing the last unknown enzyme function in the BR pathway, we clarified by in vitro enzyme assays that CPD/CYP90A catalyzes the C-3 oxidation of early BR intermediates. Based on this result we proposed an enzymologically well supported novel BR biosynthetic pathway

Optikai mikromanipuláció a biofizikában = Optical micromanipulation in biophysics

A projekt új lézercsipesz laboratórium kiépítését finanszírozta. Fő fejlesztés egy fény térmodulátorral (Spatial Light Modulator -SLM) felszerelt lézercsipesz megépítése. Ezzel tetszőlegesen sok csapda független egyidejű programozására van lehetőség. Új litográfiás berendezést is beszereztünk, ezzel mikrofluidikai eszközöket és integrált optikai elemeket készítünk. Az új laboratóriumban új típusú optikai mikromanipulációs kísérleteket végeztünk. Bonyolult alakú teszt objektumokkal összetett mozgásokat lehet megvalósítani. Négy típusú kutatást folytattunk: 1. A torziós manipulációs lehetőséget kihasználva DNS molekula csavarási tulajdonságait viszgáltuk. 2. A fotopolimerizációs struktúra építést és az új lézercsipeszt kihasználva új vizsgálati eszközöket készítettünk, mint mikroviszkozitásmérő, optikai mikromanipulátor. Modellrendszert alkottunk biológiai mozgások modellezésére: Kísérletileg kimutattuk és jellemeztük a hidrodinamikai szinkronizáció jeléenségét. 3. A folyadék mozgatásának fénnyel való vezérlését továbbfejlesztettük, a folyadék áramlási mintázatának fénnyel való változtatását oldottuk meg mikrofluidikai csatornában. 4. Integrált optikai elemeket készítettünk fotopolimerizációval mikrofluidikai alkalmazásra. Nagy érzékenységű interferometrikus szenzort készítettünk, ezt intermolekuláris reakciók jellemzésére, illetve optoelektronikai logikai áramkörök építésére alkalmaztuk. | The project supported the development of a new optical tweezers laboratory. The main development was the building of optical tweezers based on a Spatial Light Modulator (SLM). With this there is possibility to independently program an arbitrary number of optical traps. We also purchased a new photolythography device, this supportsthe building of microfluidics elements and integrated optical parts. In the new laboratory we performed novel optical manipulation experiments.We can realise complicated motions with test objects of complex shape. We worked on four types of experiments: 1. Using the possibility to rotate the trapped objects, we performed torsional manipulation experiments on DNA molecules. 2. Applying the photopolymerisation technique and the new optical tweezers we developed new experimental methods, like microviscosimeter, optical micromanipulator. We also created a model system to mimic biological motions. We experimentally demonstrated and characterised the phenomenon of hydrodynamic synchronisation. 3. We further developed the optical control of fluid flow: we realised the opticaal change of flow pattern in a microfluidics channel. 4. We built integrated optical elements for microfluidics applications. We built a high sensitivity interferometric sensor, and we used this to follow intermolecular interactions and to create optoelectronic logical circuit elements

Nonlinear Optical Investigation of Microbial Chromoproteins

Membrane-bound or cytosolic light-sensitive proteins, playing a crucial role in energy- and signal-transduction processes of various photosynthetic microorganisms, have been optimized for sensing or harvesting light by myriads of years of evolution. Upon absorption of a photon, they undergo a usually cyclic reaction series of conformations, and the accompanying spectro-kinetic events assign robust nonlinear optical (NLO) properties for these chromoproteins. During recent years, they have attracted a considerable interest among researchers of the applied optics community as well, where finding the appropriate NLO material for a particular application is a pivotal task. Potential applications have emerged in various branches of photonics, including optical information storage and processing, higher-harmonic and white-light continuum generation, or biosensorics. In our earlier work, we also raised the possibility of using chromoproteins, such as bacteriorhodopsin (bR), as building blocks for the active elements of integrated optical (IO) circuits, where several organic and inorganic photonic materials have been considered as active components, but so far none of them has been deemed ideal for the purpose. In the current study, we investigate the linear and NLO properties of biofilms made of photoactive yellow protein (PYP) and bR. The kinetics of the photoreactions are monitored by time-resolved absorption experiments, while the refractive index of the films and its light-induced changes are measured using the Optical Waveguide Lightmode Spectroscopy (OWLS) and Z-scan techniques, respectively. The nonlinear refractive index and the refractive index change of both protein films were determined in the green spectral range in a wide range of intensities and at various laser repetition rates. The nonlinear refractive index and refractive index change of PYP were compared to those of bR, with respect to photonics applications. Our results imply that the NLO properties of these proteins make them promising candidates for utilization in applied photonics, and they should be considered as valid alternatives for active components of IO circuits. © Copyright © 2020 Krekic, Zakar, Gombos, Valkai, Mero, Zimányi, Heiner and Dér

Microsecond All-Optical Modulation by Biofunctionalized Porous Silicon Microcavity

We successfully created a composite photonic structure out of porous silicon (PSi) microcavities doped by the photochromic protein, photoactive yellow protein (PYP). Massive incorporation of the protein molecules into the pores was substantiated by a 30 nm shift of the resonance dip upon functionalization, and light-induced reflectance changes of the device due to the protein photocycle were recorded. Model calculations for the photonic properties of the device were consistent with earlier results on the nonlinear optical properties of the protein, whose degree of incorporation into the PSi structure was also estimated. The successful proof-of-concept results are discussed in light of possible practical applications in the future

Self-assembling of 2,3-phenyl/thienyl-substituted acrylic acids over polycrystalline gold

The Norwegian government has submitted a report to the Norwegian parliament, concluding that raw oil export can no longer sustain economic growth. Norway is therefore seeking other industries to minimize the economic loss this is causing. Norway is already the largest exporter of salmon and trout in the world. The report states that the government's goal is to increase production to five times today's production by 2050. The ability and desire to grow has its backing from a handful of large companies dominating the aquaculture business and a newly recognized right-wing government eager to make the playroom larger for the aquaculture industry. This paper analyzes the report, using an ethical matrix, looking for ethical arguments from the government as well as defining the stakeholders affected by the government's goal. This thesis' aim is to analyze and discuss the broad range of ethical concerns, based on an ethical matrix, so that a variety of ethical perspectives can be included in an evaluative discussion

Nonlinear Optical Investigation of Microbial Chromoproteins

Membrane-bound or cytosolic light-sensitive proteins, playing a crucial role in energy- and signal-transduction processes of various photosynthetic microorganisms, have been optimized for sensing or harvesting light by myriads of years of evolution. Upon absorption of a photon, they undergo a usually cyclic reaction series of conformations, and the accompanying spectro-kinetic events assign robust nonlinear optical (NLO) properties for these chromoproteins. During recent years, they have attracted a considerable interest among researchers of the applied optics community as well, where finding the appropriate NLO material for a particular application is a pivotal task. Potential applications have emerged in various branches of photonics, including optical information storage and processing, higher-harmonic and white-light continuum generation, or biosensorics. In our earlier work, we also raised the possibility of using chromoproteins, such as bacteriorhodopsin (bR), as building blocks for the active elements of integrated optical (IO) circuits, where several organic and inorganic photonic materials have been considered as active components, but so far none of them has been deemed ideal for the purpose. In the current study, we investigate the linear and NLO properties of biofilms made of photoactive yellow protein (PYP) and bR. The kinetics of the photoreactions are monitored by time-resolved absorption experiments, while the refractive index of the films and its light-induced changes are measured using the Optical Waveguide Lightmode Spectroscopy (OWLS) and Z-scan techniques, respectively. The nonlinear refractive index and the refractive index change of both protein films were determined in the green spectral range in a wide range of intensities and at various laser repetition rates. The nonlinear refractive index and refractive index change of PYP were compared to those of bR, with respect to photonics applications. Our results imply that the NLO properties of these proteins make them promising candidates for utilization in applied photonics, and they should be considered as valid alternatives for active components of IO circuits.Peer Reviewe

CRK5 Protein Kinase Contributes to the Progression of Embryogenesis of Arabidopsis thaliana

The fine tuning of hormone (e.g., auxin and gibberellin) levels and hormone signaling is required for maintaining normal embryogenesis. Embryo polarity, for example, is ensured by the directional movement of auxin that is controlled by various types of auxin transporters. Here, we present pieces of evidence for the auxin-gibberellic acid (GA) hormonal crosstalk during embryo development and the regulatory role of the Arabidopsis thaliana Calcium-Dependent Protein Kinase-Related Kinase 5 (AtCRK5) in this regard. It is pointed out that the embryogenesis of the Atcrk5-1 mutant is delayed in comparison to the wild type. This delay is accompanied with a decrease in the levels of GA and auxin, as well as the abundance of the polar auxin transport (PAT) proteins PIN1, PIN4, and PIN7 in the mutant embryos. We have previously showed that AtCRK5 can regulate the PIN2 and PIN3 proteins either directly by phosphorylation or indirectly affecting the GA level during the root gravitropic and hypocotyl hook bending responses. In this manuscript, we provide evidence that the AtCRK5 protein kinase can in vitro phosphorylate the hydrophilic loops of additional PIN proteins that are important for embryogenesis. We propose that AtCRK5 can govern embryo development in Arabidopsis through the fine tuning of auxin-GA level and the accumulation of certain polar auxin transport proteins

Lidocaine turns the surface charge of biological membranes more positive and changes the permeability of blood-brain barrier culture models

The surface charge of brain endothelial cells forming the blood-brain barrier (BBB) is highly negative due to phospholipids in the plasma membrane and the glycocalyx. This negative charge is an important element of the defense systems of the BBB. Lidocaine, a cationic and lipophilic molecule which has anaesthetic and antiarrhytmic properties, exerts its actions by interacting with lipid membranes. Lidocaine when administered intravenously acts on vascular endothelial cells, but its direct effect on brain endothelial cells has not yet been studied. Our aim was to measure the effect of lidocaine on the charge of biological membranes and the barrier function of brain endothelial cells. We used the simplified membrane model, the bacteriorhodopsin (bR) containing purple membrane of Halobacterium salinarum and culture models of the BBB. We found that lidocaine turns the negative surface charge of purple membrane more positive and restores the function of the proton pump bR. Lidocaine also changed the zeta potential of brain endothelial cells in the same way. Short-term lidocaine treatment at a 10 μM therapeutically relevant concentration did not cause major BBB barrier dysfunction, substantial change in cell morphology or P-glycoprotein efflux pump inhibition. Lidocaine treatment decreased the flux of a cationic lipophilic molecule across the cell layer, but had no effect on the penetration of hydrophilic neutral or negatively charged markers. Our observations help to understand the biophysical background of the effect of lidocaine on biological membranes and draws the attention to the interaction of cationic drug molecules at the level of the BBB

The Arabidopsis RLCK VI_A2 Kinase Controls Seedling and Plant Growth in Parallel with Gibberellin

The plant-specific receptor-like cytoplasmic kinases (RLCKs) form a large, poorly characterized family. Members of the RLCK VI_A class of dicots have a unique characteristic: their activity is regulated by Rho-of-plants (ROP) GTPases. The biological function of one of these kinases was investigated using a T-DNA insertion mutant and RNA interference. Loss of RLCK VI_A2 function resulted in restricted cell expansion and seedling growth. Although these phenotypes could be rescued by exogenous gibberellin, the mutant did not exhibit lower levels of active gibberellins nor decreased gibberellin sensitivity. Transcriptome analysis confirmed that gibberellin is not the direct target of the kinase; its absence rather affected the metabolism and signalling of other hormones such as auxin. It is hypothesized that gibberellins and the RLCK VI_A2 kinase act in parallel to regulate cell expansion and plant growth. Gene expression studies also indicated that the kinase might have an overlapping role with the transcription factor circuit (PIF4-BZR1-ARF6) controlling skotomorphogenesis-related hypocotyl/cotyledon elongation. Furthermore, the transcriptomic changes revealed that the loss of RLCK VI_A2 function alters cellular processes that are associated with cell membranes, take place at the cell periphery or in the apoplast, and are related to cellular transport and/or cell wall reorganisation