Characterization of petite mutants of the basidiomycetes Phaffia rhodozyma CBS 5905

Small, "petite" colonies appeared with almost 1% frequency among the normally growing colonies in the astaxanthin-producing Phaffia rhodozyma (Xanthophyllomyces dendrorhous) CBS 5905 strain. These colonies fermented glucose in the presence of oxygen, were not able to grow on nonfermentable carbon sources and did not respond to inhibitors of respiration. Besides spontaneous occurrence, petite mutation proved to be inducible almost to 100% by low levels of ethidium bromide treatment. Cell hybridization experiments revealed that both the spontaneous and induced mutation was mitochondrially inherited. The RFLP pattern of the mtDNAs isolated from purified mitochondria of the grand and petite strains were similar. Consequently, unlike to the mtDNA of Saccharomyces cerevisiae, not large deletions were the reason for petite mutant induction. The size of mtDNA in the grand cells was calculated by restriction enzyme analysis and proved approximately 17.6 kb. In teleomorphic strains of P. rhodozyma (Xanthophyllomyces dendrorhous) spontaneous petite mutants did not arise and the phenotype could not be induced either by ethidium bromide treatment. According to our results, Phaffia rhodozyma is the only known petite-positive basidiomycetous yeast

Characterisation of mitochondrial haplotypes occurred in a Candida albicans population

The genetic background of mitochondrial DNA polymorphism in Candida albicans was studied by physical and functional mapping of four haplotypes identified recently in a hospital-population. The restriction patterns revealed considerable differences; however, the size of the mitochondrial DNA did not vary significantly. Sequence data demonstrated that size differences arose by short deletions, while restriction fragment length polymorphisms are caused by nucleotide substitutions in single sites. Gene rearrangement could not be detected; nevertheless, the coincidence of nucleotide substitution pattern in the inverted repeat region suggested the occurrence of homologue recombination

In vitro interactions of amphotericin B and non-antifungal compounds against opportunistic human pathogen Cryptococcus neoformans

The incidence of opportunistic human pathogen Cryptococcus neoformans caused infections have been higher during the last few decades along with the increasing number of susceptible individuals around the world. Recommended treatment of cryptococcal meningoencephalitis is a combined therapy with amphotericin B deoxycholate and flucytosine. Despite of the efficiency of this drug combination, the mortality rate of the disease is high due to the limited accessibility and the high cost of these antifungals in the most severely affected areas. The broad-spectrum activity of non-antifungal drugs and their potential to enhance the efficiency of conventional antifungal agents have been recognised previously. In this study, the in vitro activity of amantadine, valproic acid, trifluoperazine and chlorpromazine was tested against five C. neoformans strains individually and in combination with amphotericin B. All the four compounds exerted slight antifungal activity against the studied C. neoformans strains. Their combination with amphotericin B revealed additive and synergistic interactions

Investigation of the chemical durability and effectiveness of textile products with silver coating

We studied the silver content and the durability of the antimicrobial effect of commercially available silver-coated textiles. The effect of cleaning cycles on these attributions was in the focus of our work. Inductively coupled plasma mass spectrometry (ICP-MS) was used to monitor the silver content of samples, while the antimicrobial activity was tested by using four types of bacteria and four types of fungi

The role of the Aspergillus nidulans high mobility group B protein HmbA, the orthologue of Saccharomyces cerevisiae Nhp6p

The mammalian HMGB1 is a high-mobility-group B protein, which is both an architectural and functional element of chromatin. Nhp6p, the extensively studied fungal homologue of HMGB1 in Saccharomyces cerevisiae has pleiotropic physiological functions. Despite the existence of Nhp6p orthologues in filamentous ascomycetes, little is known about their physiological roles besides their contribution to sexual development. Here we study the function of HmbA, the Aspergillus nidulans orthologue of Nhp6p. We show that HmbA influences the utilization of various carbon- and nitrogen sources, stress tolerance, secondary metabolism, hyphae elongation and maintenance of polarized growth. Additionally, by conducting heterologous expression studies, we demonstrate that HmbA and Nhp6p are partially interchangeable. HmbA restores SNR6 transcription and fitness of nhp6AΔBΔ mutant and reverses its heat sensitivity. Nhp6Ap complements several phenotypes of hmbAΔ , including ascospore formation, utilization of various carbon- and nitrogen-sources, radial growth rate, hypha elongation by polarized growth. However, Nhp6Ap does not complement sterigmatocystin production in a hmbAΔ strain. Finally, we also show that HmbA is necessary for the normal expression of the endochitinase chiA , a cell wall re-modeller that is pivotal for the normal mode of maintenance of polar growth

Mikroszkópikus gombák (Aspergillus, Fusarium, Cryptococcus) mitokondriális genomszerveződésének összehasonlító elemzése = Study on the mitochondrial genome organisation of some microscopic fungi

Munkánk során meghatároztuk egy Aspergillus niger (1a típus, 31103 bp) és egy A. tübingensis (2b típus, 33656 bp) törzs teljes mitokondriális DNS szekvenciáját. A két genom géntartalma és a gének sorrendje megegyezik, különbséget mindössze a restrikciós enzimek hasítási mintázatában tapasztaltunk. Megállapítottuk, hogy a méretbeli eltérésekért a cox1, atp9 és a ndh4L gének intron-tartalma felelős. Elkészítettük a korábban már RFLP mintázat alapján elkülönített hat A. tübingensis mtDNS fizikai és funkcionális térképét. Eredményeink bizonyították, hogy a tapasztalt intraspecifikus polimorfizmus intron-szerzéssel illetve restrikciós hasítóhelyeket érintő pontmutációkkal magyarázható. Növény-patogén Fusarium törzsek biodiverzitását a mtDNS RFLP mintázata alapján tanulmányoztuk. Több haplotípust sikerült elkülönítenünk a vizsgált 3 fajban. Meghatároztuk e haplotípusok gazdanövény szerinti eloszlását. F. proliferatum lineáris, mitokondriumban lokalizált DNS plazmidjának teljes szekvenálását elvégeztük. A plazmid funkciójára jelenleg nincs bizonyítékunk. Cryptococcus neoformans két varietas-ának mtDNS szerveződését hasonlítottuk össze. Megállapítottuk, hogy a tapasztalt méretbeli különbséget a cox1, cob és LRNS gének eltérő intron-tartalma okozza. Egy másik vizsgált faj, a Trichosporon pullulans 18 kb méretű mtDNS-e a legkisebb, NADH géneket is tartalmazó mtDNS-nek bizonyult élesztőgombák között. | In the present work the complete mitochondrial DNA (mtDNA) of Aspergillus niger mtDNA type 1a (31103 bp) was sequenced and compared to the Aspergillus tubingensis type 2b (33656 bp) mtDNA. The patterns of restriction sites were similar, the gene content and order was identical. The size difference was principally attributed to the intron content of their cox1, atp9 and ndh4L genes. A. tubingensis isolates were earlier classified into six groups on the basis of the mtDNA RFLP pattern. The reason of the intraspecific mtDNA variability was investigated and proved that polymorphism due to intron acquisition and also sporadic point mutations affecting the recognition motifs of the restriction enzymes. Biodiversity of plant-pathogenic Fusarium isolates belonging to 3 different species were studied. On the basis of the RFLP pattern of their mtDNA several haplotypes were identified. The distribution of these haplotypes among host species was determined. The complete nucleotide sequence of a 10 kb linear DNA plasmid was identified, however, its function is still unknown. The functional map of the mtDNAs of two Cryptococcus neoformans varities was constructed. Characteristic sequences were cloned, sequenced and verified that the intron-content of coxI, cob and LRNA genes are responsible for the size differences of the two strains. The study of the organisation of Trichosporon pullulans mtDNA revealed that it is smallest known mtDNA among yeast carrying NADH dehidrogenase genes

The role of the Aspergillus nidulans high mobility group B protein HmbA, the orthologue of Saccharomyces cerevisiae Nhp6p

The mammalian HMGB1 is a high-mobility-group B protein, which is both an architectural and functional element of chromatin. Nhp6p, the extensively studied fungal homologue of HMGB1 in Saccharomyces cerevisiae has pleiotropic physiological functions. Despite the existence of Nhp6p orthologues in filamentous ascomycetes, little is known about their physiological roles besides their contribution to sexual development. Here we study the function of HmbA, the Aspergillus nidulans orthologue of Nhp6p. We show that HmbA influences the utilization of various carbon- and nitrogen sources, stress tolerance, secondary metabolism, hyphae elongation and maintenance of polarized growth. Additionally, by conducting heterologous expression studies, we demonstrate that HmbA and Nhp6p are partially interchangeable. HmbA restores SNR6 transcription and fitness of nhp6AΔBΔ mutant and reverses its heat sensitivity. Nhp6Ap complements several phenotypes of hmbAΔ , including ascospore formation, utilization of various carbon- and nitrogen-sources, radial growth rate, hypha elongation by polarized growth. However, Nhp6Ap does not complement sterigmatocystin production in a hmbAΔ strain. Finally, we also show that HmbA is necessary for the normal expression of the endochitinase chiA , a cell wall re-modeller that is pivotal for the normal mode of maintenance of polar growth

Green Silver and Gold Nanoparticles: Biological Synthesis Approaches and Potentials for Biomedical Applications

The nanomaterial industry generates gigantic quantities of metal-based nanomaterials for various technological and biomedical applications; however, concomitantly, it places a massive burden on the environment by utilizing toxic chemicals for the production process and leaving hazardous waste materials behind. Moreover, the employed, often unpleasant chemicals can affect the biocompatibility of the generated particles and severely restrict their application possibilities. On these grounds, green synthetic approaches have emerged, offering eco-friendly, sustainable, nature-derived alternative production methods, thus attenuating the ecological footprint of the nanomaterial industry. In the last decade, a plethora of biological materials has been tested to probe their suitability for nanomaterial synthesis. Although most of these approaches were successful, a large body of evidence indicates that the green material or entity used for the production would substantially define the physical and chemical properties and as a consequence, the biological activities of the obtained nanomaterials. The present review provides a comprehensive collection of the most recent green methodologies, surveys the major nanoparticle characterization techniques and screens the effects triggered by the obtained nanomaterials in various living systems to give an impression on the biomedical potential of green synthesized silver and gold nanoparticles