The interactome of Cryptococcus neoformans Rmt5 reveals multiple regulatory points in fungal cell biology and pathogenesis

Protein arginine methylation is a key post-translational modification in eukaryotes that modulates core cellular processes, including translation, morphology, transcription, and RNA fate. However, this has not been explored in Cryptococcus neoformans, a human-pathogenic basidiomycetous encapsulated fungus. We characterized the five protein arginine methyltransferases in C. neoformans and highlight Rmt5 as critical regulator of cryptococcal morphology and virulence. An rmt5∆ mutant was defective in thermotolerance, had a remodeled cell wall, and exhibited enhanced growth in an elevated carbon dioxide atmosphere and in chemically induced hypoxia. We revealed that Rmt5 interacts with post-transcriptional gene regulators, such as RNA-binding proteins and translation factors. Further investigation of the rmt5∆ mutant showed that Rmt5 is critical for the homeostasis of eIF2α and its phosphorylation state following 3-amino-1,2,4-triazole-induced ribosome stalling. RNA sequencing of one rmt5∆ clone revealed stable chromosome 9 aneuploidy that was ameliorated by complementation but did not impact the rmt5∆ phenotype. As a result of these diverse interactions and functions, loss of RMT5 enhanced phagocytosis by murine macrophages and attenuated disease progression in mice. Taken together, our findings link arginine methylation to critical cryptococcal cellular processes that impact pathogenesis, including post-transcriptional gene regulation by RNA- binding proteins.

Effects of Storage Time and Pre-Etching Treatment of CR-39 Detectors on Their Response to Alpha Radiation Exposure

Radon passive monitors based on solid state nuclear track detectors (SSNTD), especially CR-39, are widely used in radon and thoron studies. They may be subjected to the influence of external factors, like changing of temperature, humidity, and pressure, both before and during the measurement. Evaluation of the exposed detectors involves chemical processing, whose conditions also influence the measurement results. The aim of this study was to check several factors, as to whether they may modify the response of CR-39 detector: concerning the phase before evaluation, storage time, and temperature during storage; and concerning the evaluation procedure, etching time, and pre-etching treatment using hot water and carbon dioxide atmosphere. Two experiments were conducted by irradiation of CR-39 detectors using alpha particles emitted from a mono-energetic 241Am source and exposed in radon atmosphere. Track density dependence of the age of production was found to be statistically not significant. On the other hand, pre-etching treatment using hot water and carbon dioxide with different etching times showed statistically significant effects on track area, track sensitivity, and roundness. It was concluded that there are simple methods to increase performance of nuclear track detectors, and that storage time is not a factor of concern.

Triethylamine–Water as a Switchable Solvent for the Synthesis of Cu/ZnO Catalysts for Carbon Dioxide Hydrogenation to Methanol

Cu/ZnO catalyst precursors for industrial methanol synthesis catalysts are traditionally synthesised by coprecipitation. In this study, a new precipitation route has been investigated based on anti-solvent precipitation using a switchable solvent system of triethylamine and water. This system forms a biphasic system under a nitrogen atmosphere and can be switched to an ionic liquid single phase under a carbon dioxide atmosphere. When metal nitrate solutions were precipitated from water using triethylamine–water as the anti-solvent a hydroxynitrate phase, gerhardite, was formed, rather than the hydroxycarbonate, malachite, formed by coprecipitation. When calcined and reduced, the gerhardite precursors formed Cu/ZnO catalysts which showed better productivity for methanol synthesis from CO2 hydrogenation than a traditional malachite precursor, despite their larger CuO crystallite size determined by X-ray diffraction. The solvents could be recovered by switching to the biphasic system after precipitation, to allow solvent recycling in the process, reducing waste associated with the catalyst synthesis.

Results of studies of processes of clearing of gaseous contaminants and ventilating the atmosphere of habitable pressurized modules in a space station

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

RESULTS OF STUDIES OF THE PROCESSES OF CLEARING OF GASEOUS CONTAMINANTS AND VENTILATING THE ATMOSPHERE OF HABITABLE PRESSURIZED MODULES IN A SPACE STATION

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

A CO2-Mediated Conjugate Cyanide Addition to Chalcones

Carbon dioxide is an intrinsically stable molecule; however, it can readily react with various nucleophilic reagents. In the presence of a cyanide source, CO2 was proven to be useful to promote addition reactions. Here we report the use of CO2 to facilitate 1,4-conjugate cyanide addition reaction to chalcones to generate organonitriles. Nitriles are key component in organic synthesis due to their utility in numerous functional group transformation, however, conjugation addition of cyanide has been a challenge in this substrate class due to side reactions. To mitigate this, we employed simple ammonium and metal cyanide sources as nucleophiles under carbon dioxide atmosphere where high selectivity toward the desired product was obtained. The presented reaction is not feasible under inert atmosphere, which highlights the important role of CO2, as a Lewis and Brøndsted acidic catalyst. Further derivatization of organonitriles compounds were performed to showcase the utility of the reaction, while an unprecedented dimerization reaction was identified and characterized, affording a cyclopentanone scaffold.

Valorization Potential of Oilseed Cakes by Subcritical Water Extraction

The oil industry generates great quantities of oilseed cakes that remain after oil extraction. New technologies are required for their valorization, owing to their high nutritional value. Pumpkin, flax and hemp seed cakes were extracted by subcritical water under different conditions that included different gas atmospheres and homogenous catalysis, and for the first time their properties were directly compared. Extracts obtained in a nitrogen atmosphere, nitrogen atmosphere with the addition of a catalyst, and carbon dioxide atmosphere were chemically and nutritionally characterised. In the aqueous extracts obtained under different extraction conditions, the content of lipids, proteins and selected minerals (calcium, potassium, sodium and phosphorus) were determined. A detailed amino acid profile was determined by chromatographic analysis. The highest relative content of essential amino acids was observed in pumpkin seed extracts (51.49 ± 0.47 to 58.58 ± 0.45 mg/100 g dry extract), whereas hemp seed extracts were the richest in flavour amino acids aspartic acid, glutamic acid and alanine. Extraction in a carbon dioxide atmosphere or in nitrogen atmosphere with a HCl modifier released generally more minerals into the aqueous phase. Aqueous oilseed cake extracts demonstrated a favorable chemical composition and great nutritional value, opening new possibilities for exploitation of this biowaste. Based on the obtained results, oilseed cake extracts obtained by subcritical water have great potential to be used for the fortification of different food products, as well as in cosmetics.