The Genetic Components of a Natural Color Palette: A Comprehensive List of Carotenoid Pathway Mutations in Plants

Carotenoids comprise the most widely distributed natural pigments. In plants, they play indispensable roles in photosynthesis, furnish colors to flowers and fruit and serve as precursor molecules for the synthesis of apocarotenoids, including aroma and scent, phytohormones and other signaling molecules. Dietary carotenoids are vital to human health as a source of provitamin A and antioxidants. Hence, the enormous interest in carotenoids of crop plants. Over the past three decades, the carotenoid biosynthesis pathway has been mainly deciphered due to the characterization of natural and induced mutations that impair this process. Over the year, numerous mutations have been studied in dozens of plant species. Their phenotypes have significantly expanded our understanding of the biochemical and molecular processes underlying carotenoid accumulation in crops. Several of them were employed in the breeding of crops with higher nutritional value. This compendium of all known random and targeted mutants available in the carotenoid metabolic pathway in plants provides a valuable resource for future research on carotenoid biosynthesis in plant species.

Biogenesis of mature piRNAs in Caenorhabditis elegans is dependent on orchestration between multiple ribonucleases and PRG-1

Piwi-interacting RNAs (piRNAs) are an animal-specific class of germline-enriched small non-coding RNAs that shape transcriptome, as well as ensure genomic integrity and fertility by regulating transposons and other selfish genetic elements. In Caenorhabditis elegans mature piRNAs are 21-nucleotides long, begin with a monophosphorylated uridine, and they associate with PRG-1 to form piRISCs that scan the transcriptome for non-self sequences. However, these piRNAs are born as longer 5-capped transcripts, where PARN-1, a 3-5 exoribonuclease, contributes to the formation of the mature 3-end. But, till date, the 5-processing events remain elusive. We demonstrate that the recently identified endoribonuclease activity of XRN-2 is involved in the processing of the 5-end of precursor piRNAs in worms. Depletion of XRN-2 results in reduced mature piRNA levels, with concomitant increase in levels of the 5-capped precursors. We also reveal that the piRNAs born as longer precursor molecules (>60 nt), prior to 5-end processing, undergo ENDU-1-mediated endoribonucleolytic processing of their 3-ends. Our in vitro RNA-protein interaction studies unravel the mechanistic interactions between XRN-2 and PRG-1 towards the formation of mature 5-ends of piRNAs. In vivo experiments employing prg-1 mutant worms indicate that XRN-2 has the potential to perform clearance of precursors that are not bound and protected by PRG-1. Finally, we also demonstrate that XRN-2 is not only important for the generation of mature piRNAs and piRNA-dependent endo-siRNAs, but through yet unknown pathways, it also affects piRNA-independent endo-siRNAs that shape transcriptome, as well as contribute to genomic integrity via regulation of transposable elements.

Effect of arginine, putrescine and spermidine on the polyamine, proline and chlorophyll content of tobacco (Nicotiana tabacum L.)

Polyamines, such as spermidine (Spd) spermine (Spm) and their direct precursor, the diamine putrescine (Put) are vital and essential aliphatic amines which are also present in plants. Although ethylene and polyamines are also involved in fruit ripening, the genes coding them must also take part in other biosynthetic pathways. In the ethylene and polyamines play an important role in development of salt stress tolerance, and in responses for biotic and abiotic stresses. Exogenous application of all three main polyamines (Put, Spd, Spm) increase salt tolerance of plants, but, accordingly to previous experiments, spermidine has the main effect on the enhancement of salt tolerance. Nicotiana tabacum L. plants were grown in vitro on MS medium, the treatments were as follows: arginine (150 mg l-1), putrescine (10 mg l-1), spermidine (10 mg l-1). Proline, chlorophyll a, b and polyamine contents were measured. The obtained results show that the arginine decarboxylase and the spermidine synthase genes involved in polyamine metabolism, cannot be enhanced by exogenous addition of their precursor molecules. On the contrary, the spermine synthase gene has a positive effect to the lower-class forms of polyamines.

Temperature-Dependent Crystallization Mechanisms of Methylammonium Lead Iodide Perovskite From Different Solvents

Hybrid perovskites are a novel type of semiconductors that show great potential for solution-processed optoelectronic devices. For all applications, the device performance is determined by the quality of the solution-processed perovskite thin films. During solution processing, the interaction of solvent with precursor molecules often leads to the formation of solvate intermediate phases that may diverge the crystallization pathway from simple solvent evaporation to a multi-step formation process. We here investigate the crystallization of methylammonium lead iodide (MAPbI3) from a range of commonly utilized solvents, namely dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and gamma-butyrolactone (GBL) at different temperatures ranging from 40°C to >100°C by in-situ grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. For all solvents but GBL, we clearly observe the formation of solvate-intermediate phases at moderate processing temperatures. With increasing temperatures, an increasing fraction of the MAPbI3 perovskite phase is observed to form directly. From the temperature-dependence of the phase-formation and phase-decomposition rates, the activation energy to form the MAPbI3 perovskite phase from the solvate-phases are determined as a quantitative metric for the binding strength of the solvent within the solvate-intermediate phases and we observe a trend of DMSO > DMF > NMP > GBL. These results enable prediction of processing temperatures at which solvent molecules can be effectively removed.

Irradiation-driven molecular dynamics simulation of the FEBID process for Pt(PF3)4

This paper presents a detailed computational protocol for the atomistic simulation of formation and growth of metal-containing nanostructures during focused electron beam-induced deposition (FEBID). The protocol is based upon irradiation-driven molecular dynamics (IDMD), a novel and general methodology for computer simulations of irradiation-driven transformations of complex molecular systems by means of the advanced software packages MBN Explorer and MBN Studio. Atomistic simulations performed following the formulated protocol provide valuable insights into the fundamental mechanisms of electron-induced precursor fragmentation and the related mechanism of nanostructure formation and growth using FEBID, which are essential for the further advancement of FEBID-based nanofabrication. The developed computational methodology is general and applicable to different precursor molecules, substrate types, and irradiation regimes. The methodology can also be adjusted to simulate the nanostructure formation by other nanofabrication techniques using electron beams, such as direct electron beam lithography. In the present study, the methodology is applied to the IDMD simulation of the FEBID of Pt(PF3)4, a widely studied precursor molecule, on a SiO2 surface. The simulations reveal the processes driving the initial phase of nanostructure formation during FEBID, including the nucleation of Pt atoms and the formation of small metal clusters on the surface, followed by their aggregation and the formation of dendritic platinum nanostructures. The analysis of the simulation results provides spatially resolved relative metal content, height, and growth rate of the deposits, which represents valuable reference data for the experimental characterization of the nanostructures grown by FEBID.

Interaction of cisplatin anticancer drug with C20 bowl: DFT investigation

This study investigated the cisplatin (anticancer drug) interaction with C20 bowl and C20H10(Bowl) molecule including hydrogen-saturated with using mPW1PW91 functional. The stability of the various isomers of drug interaction with C20 bowl was investigated. The interaction energy values were estimated in these systems. Changes in the structural parameters and the frontier orbital energy and HOMO-LUMO gap values were evaluated. Charge transfer between fragments were shown with electrophilicity-based charge transfer (ECT). The Octanol–water partition coefficient (log P) and molecular volume (Vm) of these drug precursor molecules were studied. Also, Pt-C bond characterizations were illustrated using QTAIM analysis. The results showed that C20 bowl can be a promising nanocarrier for cisplatin anticancer drug.

Proceso Sol-Gel en la Síntesis de Dióxido de Silicio (Sio2)

En ciencia de los materiales el dióxido de silicio, también conocido como sílice, ha recibido significante atención en diferentes áreas de investigación, ganando un espacio importante y de mucho interés entre los investigadores, debido a sus diversas aplicaciones que abarcan desde la síntesis de soportes para catalizadores hasta materiales para la liberación controlada de fármacos. Es motivo por el cual, en este manuscrito se dan a conocer aspectos químicos fundamentales e importantes sobre el proceso sol-gel en la síntesis de la sílice a partir de moléculas precursoras de alcóxidos de silicio y organosilanos. Se analiza cómo el catalizador ácido/básico y el tipo de precursor afectan a las reacciones de hidrólisis y condensación, así como a la estructura y morfología del material. Palabra clave: Sílice, Sol-gel, Hidrólisis, Condensación, Alcóxido. Abstract In materials science, silicon dioxide has received significant attention in different research areas, gaining valuable space and interest between researchers due to its diverse applications, ranging from the synthesis of supports for catalysts to materials for controlled drug liberation. Herein we describe fundamental and important chemical aspects of the sol-gel process in the synthesis of silica, starting from precursor molecules of silicon alkoxides and organosilanes. Moreover, this review analyses how the acid/basic catalyst and the type of precursor affect the hydrolysis and condensation reaction, as well as the structure and morphology of the obtained material. Keywords: Silica, Sol-gel, Hydrolysis, Condensation, Alkoxide.

Effect of Vibrio-Derived Extracellular Protease vEP-45 on the Blood Complement System

Vibrio vulnificus is a pathogenic bacterium that can causes wound infections and fetal septicemia. We have reported that V. vulnificus ATCC29307 produces an extracellular zinc-metalloprotease (named vEP-45). Our previous results showed that vEP-45 can convert prothrombin to active thrombin and also activate the plasma kallikrein/kinin system. In this study, the effect of vEP-45 on the activation of the complement system was examined. We found that vEP-45 could proteolytically convert the key complement precursor molecules, including C3, C4, and C5, to their corresponding active forms (e.g., C3a, C3b, C4a, C4b, and C5a) in vitro cleavage assays. C5b production from C5 cleavage mediated by vEP-45 was not observed, whereas the level of C5a was increased in a dose-dependent manner compared to that of the non-treated control. The cleavage of the complement proteins in human plasma by vEP-45 was also confirmed via Western blotting. Furthermore, vEP-45 could convert C3 and C5 to active C3a and C5a as a proinflammatory mediator, while no cleavage of C4 was observed. These results suggest that vEP-45 can activate the complement system involved in innate immunity through an alternative pathway.

Nanosensors Based on Structural Memory Carbon Nanodots for Ag+ Fluorescence Determination

Ag+ pollution is great of harm to the human body and the biology. Therefore, it is an urgent need to develop inexpensive and accurate detection methods. Herein, lignin-derived structural memory carbon nanodots (CSM-dots) with outstanding fluorescence property were fabricated via a green method, which reserve functional and structural units of the precursor molecules. The CSM-dots could specifically bind Ag+, accompanied with a remarkable fluorescence quenching response. This “turn-off” fluorescence behavior was used for Ag+ determination in a linear range of 5-290 μM with the detection limit as low as 500 nM. Furthermore, the finding showed that this sensing nano-platform was successfully used for Ag+ determination in real samples and intracellular imaging, showing great potential in biological and environmental monitoring applications.

Epitaxial Graphene on 4H-SiC (0001) as a Versatile Platform for Materials Growth: Mini-Review

Material growth on a dangling-bond-free interface such as graphene is a challenging technological task, which usually requires additional surface pre-treatment steps (functionalization, seed layer formation) to provide enough reactive sites. Being one of the most promising and adaptable graphene-family materials, epitaxial graphene on SiC, due to its internal features (substrate-induced n-doping, compressive strain, terrace-stepped morphology, bilayer graphene nano-inclusions), may provide pre-conditions for the enhanced binding affinity of environmental species, precursor molecules, and metal atoms on the topmost graphene layer. It makes it possible to use untreated pristine epitaxial graphene as a versatile platform for the deposition of metals and insulators. This mini-review encompasses relevant aspects of magnetron sputtering and electrodeposition of selected metals (Au, Ag, Pb, Hg, Cu, Li) and atomic layer deposition of insulating Al2O3 layers on epitaxial graphene on 4H-SiC, focusing on understanding growth mechanisms. Special deliberation has been given to the effect of the deposited materials on the epitaxial graphene quality. The generalization of the experimental and theoretical results presented here is hopefully an important step towards new electronic devices (chemiresistors, Schottky diodes, field-effect transistors) for environmental sensing, nano-plasmonics, and biomedical applications.