Temperature-stress tolerance of the fungal strain Aspergillus niger 26: physiological and ultrastructural changes.

The study focuses on the morphological and physiological cell responses to oxidative stress induced by high temperature treatment in the industrially relevant fungus Aspergillus niger 26. Temperatures above 30 °C lead to growth suppression and changes in morphological characteristics: decrease in the size of hyphal elements and increase in "active length" by switching from slightly branched long filaments to a multitude of branched forms containing active cytoplasm. Transmission electron microscopy of fungal cultures heated at 40 °C demonstrated abnormal wavy septation with reduced amount of chitin (as shown by WGA-gold labelling), intrahyphal hyphae development, disintegration of mitochondria and extensive autolysis.

Copper stress and filamentous fungus Humicola lutea 103 - ultrastructural changes and activities of key metabolic enzymes.

Humicola lutea 103 is a copper-tolerant fungal strain able to grow in the presence of 300 μg·mL(-1) Cu(2+) under submerged cultivation. To prevent the consequences of copper overload, microorganisms have evolved molecular mechanisms that regulate its uptake, intracellular traffic, storage, and efflux. In spite of this avoidance strategy, high heavy-metal concentrations caused distinct and widespread ultrastructural alterations in H.

Heat-shock-induced oxidative stress and antioxidant response in Aspergillus niger 26.

To extend the knowledge about the relationship between heat shock and oxidative stress in lower eukaryotes, the filamentous fungus Aspergillus niger 26 was chosen as a model system. Here, the response of A. niger cells to heat shock is reported.

Unusual location and characterization of Cu/Zn-containing superoxide dismutase from filamentous fungus Humicola lutea.

The present study aims to provide new information about the unusual location of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) in lower eukaryotes such as filamentous fungi. Humicola lutea, a high producer of SOD was used as a model system. Subcellular fractions [cytosol, mitochondrial matrix, and intermembrane space (IMS)] were isolated and tested for purity using activity measurements of typical marker enzymes.

Radical quenching by rosmarinic acid from Lavandula vera MM cell culture.

This study was conducted to evaluate the radical scavenging capacities of extracts and preparations from a Lavandula vera MM plant cell culture with different rosmarinic acid content and to compare them with pure rosmarinic and caffeic acids as well. The methods, which were used are superoxide anion and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radicals scavenging assays. Results showed that extracts and preparations from Lavandula vera MM possess strong radical scavengers, as the best both radical scavengers appeared to be the fractions with enriched rosmarinic acid content, obtained after ethylacetate fractioning (47.

Oxidative stress response of filamentous fungi induced by hydrogen peroxide and paraquat.

Although, oxidative stress response, which protects organisms from deleterious effects of reactive oxygen species (ROS), has been extensively studied in pro- and eukaryotes, the information about filamentous fungi is fragmentary. We investigated the effect of two ROS-generating agents (paraquat, PQ, and H2O2) on cellular growth and antioxidant enzyme induction in 12 fungal species. Our results indicate that exposure of fungal spores or mycelia to PQ and H2O2 promoted oxidative stress, as evidenced by remarkable inhibition of spore germination and biomass production; stimulation of cyanide-resistant respiration; accumulation of oxidative modified proteins.

In vitro antioxidant activity of polyphenol extracts with antiviral properties from Geranium sanguineum L.

Recent evidence shows that plant polyphenols exhibit antioxidant and radical scavenging properties. By three separate and complementary methods--DPPH assay, beta-carotene-linoleic acid assay and NBT-reduction assay it was established that a polyphenol-rich extract from the medicinal plant Geranium sanguineum L. with strong anti-influenza virus activity, possessed antioxidant and radical scavenging capacities.

Effect of Cu/Zn-superoxide dismutase from the fungal strain Humicola lutea 103 on antioxidant defense of Graffi tumor-bearing hamsters.

A novel Cu/Zn-containing superoxide dismutase (SOD) was isolated from the fungal strain Humicola lutea 103. Previously, a protective effect of this enzyme (HLSOD) against tumor growth and also superoxide production in Graffi tumor-bearing hamsters (TBH) were established. The aim of the present study was to investigate the effect of HLSOD on the activity of endogenous SOD and catalase in the cells from TBH during tumor progression.

A novel glycosylated Cu/Zn-containing superoxide dismutase: production and potential therapeutic effect.

The fungal strain Humicola lutea 103 produces a naturally glycosylated Cu/Zn SOD. To improve its yield, the effect of an increased concentration of dissolved oxygen (DO) on growth and enzyme biosynthesis by the producer, cultivated in a 3 l bioreactor, was examined. Exposure to a 20% DO level caused a 1.