A mutant strain of Aspergillus nidulans is hypersensitive to cycloheximide

We routinely use a strain derived from the master strain A513 (FGSC) for mitotic linkage studies in our laboratory. This strain carries the ActA1 mutation on linkage group III, which should confer resistance to actidione (trade name for cycloheximide). However, we have observed that our strain 513s is hypersensitive to actidione in comparison with a wild-type strain at the ActA1 locus (our collection)

Mapping of mutants resistant to p-fluorophenylalanine in diploid Aspergillus nidulans, lethal in haploids

In a previous paper (Babudri and Morpurgo 1990 Curr. Genet. 17:519-522) we described a new class of para-fluorophenylalanine (FPA) resistant mutants in Aspergillus nidulans. These mutants were obtained by plating UV irradiated diploid conidia on minimal medium (MM) supplemented with FPA (0.188 mg/ml)

Kumagawa and Soxhlet solvent fractionation of lignin: impact on the chemical structure

We investigated the effects of solvent fractionation on the chemical structures of two commercial technical lignins. We compared the effect of Soxhlet and Kumagawa extraction. The aim of this work was to compare the impact of the methods and of the solvents on lignin characteristics. Our investigation confirmed the potentialities of fractionation techniques in refining lignin properties and narrowing the molecular weight distribution. Furthermore, our study revealed that the Kumagawa process enhances the capacity of oxygenated solvents (ethanol and tetrahydrofuran) to extract lignin that contains oxidized groups and is characterized by higher average molecular weights. Furthermore, the use of tetrahydrofuran after ethanol treatment enabled the isolation of lignin with a higher ratio between carbonyl and other oxidized groups. This result was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C NMR and two-dimensional (2D) NMR spectroscopies, gel permeation chromatography (GPC), and analytical pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS) analysis. Ultraviolet–visible (UV–vis) spectra evidenced the enrichment in the most conjugated species observed in the extracted fractions. Elemental analyses pointed at the cleavage of C-heteroatom bonds enhanced by the Kumagawa extraction

Integrated tools for quality promotion and project control

Public administrations, called upon to integrate the principles and criteria of Do No Significant Harm (DNSH) and Environmental Social, Governance (ESG) in the planning, design and production of their investments, now find themselves operating within new decision-making scenerios and models, in the very broad framework of standards, including specialised ones, certification protocols and framework levels for sustainability assessment and reporting. This paper reports on a research experience aimed at defining tools and guidelines to incentivise and assess the environmental and social quality of projects and works (a collaboration between Agenzia del Demanio and Politecnico di Milano). It documents the challenges, limits and opportunities arising from overlapping compulsory regulations, standards and voluntary certification protocols for the qualification of public works

UV light induced accumulation of variability in a diploid strain of Aspergillus nidulans

The accumulated variability in asexual species was evaluated in Aspergillus nidulans diploid cells after repeated cycles of UV irradiation. The results show that diploid cells can accumulate a very high genetic variability in the heterozygous condition as previously shown with the base analog 6-N-hydroxylaminopurine (HAP)

Genotoxic activity of 2-amino-N-hydroxylaminopurine (AHA) in Aspergillus nidulans

In Aspergillus nidulans, as well as in other eukaryotic cells, not all base analogs are mutagenic. For example, 2-aminopurine (2-AP) is non-mutagenic or weakly mutagenic for eukaryotes while it is mutagenic for bacteria. Because of their potential use in genetical research, an effort has been made to find base analogs mutagenic for eukaryotic cells. Work in this field has been successful: in fact, 6- hydroxylamino-purine (HAP) and 2-amino-N-hydroxylaminopurine (AHA) have been found mutagenic for yeast as well as for other eukaryotic cells. (Pavlov et al. 1991, Mut. Res. 253:33-46). In particular, Brockman et al. (Mut. Res. 177:61-75, 1987) tested the mutagenic activity of HAP and AHA in Neurospora crassa and found that AHA is about equally mutagenic as HAP at low doses but more mutagenic at high doses. In this paper we report the genotoxic activity of AHA in A. nidulans. In this mold, we have tested AHA-induced lethality and mutagenic and recombinogenic effect

The exceptionally high rate of spontaneous mutations in the polymerase delta proofreading exonuclease-deficient Saccharomyces cerevisiae strain starved for adenine

BACKGROUND: Mutagenesis induced in the yeast Saccharomyces cerevisiae by starvation for nutrilites is a well-documented phenomenon of an unknown mechanism. We have previously shown that the polymerase delta proofreading activity controls spontaneous mutagenesis in cells starved for histidine. To obtain further information, we compared the effect of adenine starvation on mutagenesis in wild-type cells and, in cells lacking the proofreading activity of polymerase delta (phenotype Exo(-), mutation pol3-01). RESULTS: Ade(+ )revertants accumulated at a very high rate on adenine-free plates so that their frequency on day 16 after plating was 1.5 × 10(-4 )for wild-type and 1.0 × 10(-2 )for the Exo(- )strain. In the Exo(- )strain, all revertants arising under adenine starvation are suppressors of the original mutation, most possessed additional nutritional requirements, and 50% of them were temperature sensitive. CONCLUSIONS: Adenine starvation is highly mutagenic in yeast. The deficiency in the polymerase delta proofreading activity in strains with the pol3-01 mutation leads to a further 66-fold increase of the rate of mutations. Our data suggest that adenine starvation induces genome-wide hyper-mutagenesis in the Exo(- )strain

Nanostructuring poly-[2-methoxy-5-(2′-ethyl-hexiloxy)-p-phenylenevinylene] thin films by high-temperature soft lithography

Abstract Sub micron patterning of the conjugated polymer, poly-[2-methoxy-5-(2′-ethyl-hexiloxy)-p-phenylenevinylene] (MEH-PPV) has been achieved by high-temperature soft lithography. The process has been carried out by placing a spin-coated polymer film in conformal contact with elastomeric replicas of master structures fabricated by electron beam lithography. The system is then heated to decrease the polymer viscosity, allowing the pattern transfer with resolution down to 300 nm. The well-preserved photoluminescence spectrum and efficiency of the emissive polymer clearly indicate that high-temperature soft lithography can be successfully applied for the one-step realization of organic-based devices

ENVIRONMENTAL STRESS AND MUTAGENESIS IN ENTERIC AND NON-ENTERIC BACTERIA

Mutations are fundamental for evolution. For many years it has been thought that mutagenesis occurs only in dividing cells. Now it is clear that mutations arise in non-dividing or slowly dividing microorganisms. Natural populations spend most of the time in stressful environments where their growth rate is highly reduced. Thus, the existence of a mutagenesis process, independent of multiplication (stress-induced mutagenesis, SIM), might have a profound evolutionary role. In the presented paper we review the stateof-the-art in enteric and non-enteric bacteria. We describe different experimental systems as well as the mechanisms and models presented to explain the huge amount of data obtained in more than twenty years of research