Herbicide Metabolism in Weeds — Selectivity and Herbicide Resistance

The metabolic detoxication/bioactivation pathways, the levels and activity of enzymes, and endogenous cofactors mediating these reactions in crops have been well documented; however, much less evidence has been accumulated in weed species. The herbicide metabolism as a selectivity factor is summarized with special attention to acetyl-CoA carboxylases (ACCase)-inhibiting aryloxyphenoxypropionate, protoporphyrinogen IX oxidase (PPO) inhibitor, carotenoid biosynthesis inhibitor clomazone, and acetolactate synthase (ALS) inhibitor imidazolinone and sulfonylurea herbicides in various weed species. The metabolism-based herbicide resistance related to these herbicide classes is also discussed along with the role and level of metabolizing enzymes and cofactors in weed species

Multiple inclusion complex formation of protonated ellipticine with cucurbit[8]uril: thermodynamics and fluorescence properties

The encapsulation of protonated ellipticine (EH+) in the cavity of cucurbit[8]uril (CB8) was studied in water at pH 4 with spectrophotometric, fluorescence spectroscopic and isothermal calorimetric measurements. The formation of three types of inclusion complexes was observed depending on the host and guest concentrations. Not only one, but also two EH+ was capable of encapsulation in CB8 in 37 μM EH+ solution and the thermodynamics of the binding steps were revealed. The produced very stable complexes showed markedly different absorption and fluorescence properties. When large excess of CB8 was employed in dilute (0.49 μM) EH+ solution, sequential binding of two CB8 occurred to the monomer alkaloid bringing about a substantial alteration in the fluorescence decay kinetics. The driving force of the 1:2 guest:host complex formation was much lower than that of 1:1 encapsulation. © 2016 Informa UK Limited, trading as Taylor & Francis Grou

Polyamidoamine dendrimer impairs mitochondrial oxidation in brain tissue

Background: The potential nanocarrier polyamidoamine (PAMAM) generation 5 (G5-NH2) dendrimer has been shown to evoke lasting neuronal depolarization and cell death in a concentration-dependent manner. In this study we explored the early progression of G5-NH2 action in brain tissue on neuronal and astroglial cells.Results: In order to describe early mechanisms of G5-NH2 dendrimer action in brain tissue we assessed G5-NH2 trafficking, free intracellular Ca2+ and mitochondrial membrane potential (ΨMITO) changes in the rat hippocampal slice by microfluorimetry. With the help of fluorescent dye conjugated G5-NH2, we observed predominant appearance of the dendrimer in the plasma membrane of pyramidal neurons and glial cells within 30 min. Under this condition, G5-NH2 evoked robust intracellular Ca2+ enhancements and ΨMITO depolarization both in pyramidal neurons and astroglial cells. Intracellular Ca2+ enhancements clearly preceded ΨMITO depolarization in astroglial cells. Comparing activation dynamics, neurons and glia showed prevalence of lasting and transient ΨMITO depolarization, respectively. Transient as opposed to lasting ΨMITO changes to short-term G5-NH2 application suggested better survival of astroglia, as observed in the CA3 stratum radiatum area. We also showed that direct effect of G5-NH2 on astroglial ΨMITO was significantly enhanced by neuron-astroglia interaction, subsequent to G5-NH2 evoked neuronal activation.Conclusion: These findings indicate that the interaction of the PAMAM dendrimer with the plasma membrane leads to robust activation of neurons and astroglial cells, leading to mitochondrial depolarization. Distinguishable dynamics of mitochondrial depolarization in neurons and astroglia suggest that the enhanced mitochondrial depolarization followed by impaired oxidative metabolism of neurons may be the primary basis of neurotoxicity. © 2013 Nyitrai et al.; licensee BioMed Central Ltd

Nanocsövek előállítása, szerkezete és tulajdonságai = Preparation, structure, and properties of nanotubes

A kutatások célja a szén nanocsövek elektrokémiai úton történő előállítása során keletkező termék tulajdonságainak és a technológiai paraméterek közötti összefüggések kimutatása volt. A gyártási paraméterek között a szén katód alapanyagának morfológiája, a só olvadék összetétele, a hőmérséklet, valamint az elektrokémiai művelet paraméterei (áramsűrűség, potenciál, az elektrolízishez szükséges idő) bizonyultak lényegesnek. Az előállítási műveletekkel kapcsolatban megvizsgáltuk az elektrokémiai fémleválasztás kinetikáját is, amely a nanocső szintézis jobb megértését eredményezte. A nanocsöveket tartalmazó termék megtisztítása és az ehhez a lépéshez szükséges eljárások tanulmányozása képezte második feladatot. Tanulmányoztuk azokat a tisztítási módszereket is, amelyek segítségével a nanocsövek felülete módosítható. A nanocsöveket tartalmazó készítményt alagúteffektuson alapuló mikroszkópos vizsgálatoknak vetettük alá, és a pásztázó tűszondás mikroszkóppal meghatároztuk a csövek méretét, alakját, az egyes típusokba sorolt csövek gyakoriságát. A kísérleti eredményeket statisztikai módszerekkel értékeltük ki. A vizsgálatokat elméleti számításokkal egészítettük ki, amelyek célja annak megállapítása volt, hogy a különböző osztályokba sorolható nanocsövek mennyire stabilak. E vizsgálatok céljából több módszerrel is meghatároztuk a csövek aromás jellegét. | The main aim of this research was to determine the correlation between the parameters of the electrolysis and the experimental properties of the carbon nanotubes. The most important parameters, which could affect the quality of the nanotubes were found to be the morphology of the carbon cathode, the composition of the molten salt, the temperature and the parameters of the electrolysis itself (current density, applied potential, and the time period of electrolysis). In connection with these tasks we also studied the mechanism of metal deposition, which yielded new information on the formation of nanotubes. The second object of these investigations was the purification of nanotubes and the necessary steps needed to accomplish this task. Probes containing nanotubes were be investigated by using scanning-tunneling and atomic force microscopes. These investigations revealed the distribution of the various shapes, and thickness of the tubes. The experimental data were evaluated by using statistical methods. Experimental investigations were completed by theoretical calculations. The aim of these investigations was to determine the stability of various types of nanotubes

The Janus facet of nanomaterials

Application of nanoscale materials (NMs) displays a rapidly increasing trend in electronics, optics, chemical catalysis, biotechnology, and medicine due to versatile nature of NMs and easily adjustable physical, physicochemical, and chemical properties. However, the increasing abundance of NMs also poses significant new and emerging health and environmental risks. Despite growing efforts, understanding toxicity of NMs does not seem to cope with the demand, because NMs usually act entirely different from those of conventional small molecule drugs. Currently, large-scale application of available safety assessment protocols, as well as their furthering through case-by-case practice, is advisable. We define a standard work-scheme for nanotoxicity evaluation of NMs, comprising thorough characterization of structural, physical, physicochemical, and chemical traits, followed by measuring biodistribution in live tissue and blood combined with investigation of organ-specific effects especially regarding the function of the brain and the liver. We propose a range of biochemical, cellular, and immunological processes to be explored in order to provide information on the early effects of NMs on some basic physiological functions and chemical defense mechanisms. Together, these contributions give an overview with important implications for the understanding of many aspects of nanotoxicity

Highly sensitive fluorescence response to inclusion complex formation of berberine alkaloid with cucurbit[7]uril

The effect of inclusion complex formation on the fluorescence properties of berberine, a clinically important natural alkaloid, was studied using cucurbit[7]uril as macrocyclic host compound. The formation of a very stable 1:1 inclusion complex led to about 500-fold fluorescence intensity enhancement, which facilitated the detection of berberine even below nanomolar concentration. Addition of NaCl caused a significant change in the association constant and the fluorescence characteristics of the complex, whereas the variation of the anion had a small effect. 1-Alkyl-3-methylimidazolium type ionic liquids altered the fluorescent properties of the berberine-cucurbit[7]uril complex much more efficiently than did NaCl. Time-resolved fluorescence studies showed ternary complex formation. Because berberine fluorescence is insensitive to pH and increases substantially upon inclusion in cucurbit[7]uril, the reversible self-assembly of this host-guest pair may find analytical application in enzyme assays