Yeasts take up iron by three main mechanisms. In the reductive uptake mechanism, specialized flavo-hemoproteins (Fre) dissociate extracellular ferric complexes by reduction involving trans-plasma membrane electron transfer. The resulting free iron is then imported by a high-affinity permease system (Ftr), coupled to a copper-dependent oxidase (Fet), which channels iron through the plasma membrane. As a consequence, iron uptake by this mechanism is dependent on the availability of copper. In the siderophore-mediated mechanism, siderophores excreted by the cells or produced by other bacterial or fungal species are taken up without prior dissociation, via specific, copper-independent high-affinity receptors. The iron is then dissociated from the siderophores intracellularly, probably by reduction. In the heme uptake mechanism, free heme or heme bound to hemoglobin is taken up as such, probably by endocytosis. Iron is released intracellularly after hydrolysis of the porphyrin ring catalyzed by heme oxygenase. Within the cell, iron is stored in vacuoles or in siderophores.

Iron can be mobilized from vacuoles by a reductive mechanism homologous to that found at the plasma membrane. Regulation of iron uptake and iron use are mediated by transcriptional regulators acting either as activators in iron-deficient conditions or as repressors in iron-rich conditions, according to the yeast species; these regulators thus adjust the iron uptake flux to the cell's requirements. In the baker's yeast, Saccharomyces cerevisiae, a post-transcriptional mechanism is active under low iron conditions, involving the degradation of RNAs encoding inessential iron-utilizing proteins. Other fungi have mechanisms serving a similar purpose at the transcriptional level. Studies in S. cerevisiae show that mitochondria are central to regulating cellular iron homeostasis, through the synthesis of iron-sulfur clusters.

Further reading: Iron Uptake and Homeostasis in Microorganisms

Labels: fungal, fungi, Iron acquisition mechanisms, Iron transporters, Iron uptake in Yeasts, Iron uptake systems, Iron-homeostasis, Iron-uptake, mycology, Siderophores, yeast, Yeasts

A list of conferences, meetings, symposia and workshops relating to all aspects of mycology, yeast and fungal science and medicine.

February 1 - 14, 2009. Comparative analysis of in vitro and in vivo Candida albicans-host interaction systems
Madrid, Spain Further information
Federation of European Biochemical Societies advanced practical and lecture course. The aim of this two-week course is to introduce students to the latest techniques of in vivo infection and ex-vivo/in vitro interaction models between the human pathogen Candida albicans and the host.
Suggested reading: Candida Book

March 17 - 22, 2009. 25th Fungal Genetics Conference
Asilomar, California, USA Further information
Billed as the biggest worldwide conference on genetics of filamentous fungi.
Suggested reading: Aspergillus: Molecular Biology and Genomics

March 29 - 31, 2009. British Society for Medical Mycology (BSMM) Annual Scientific Meeting
Imperial College London, UK Further information
Translational Research in Medical Mycology
Suggested reading: Mycology Books

April 6 - 7, 2009. Economic and Social Impact of Fungal Deteriogens
Manchester, UK Further information
Organised by the British Mycological Society and the International Biodeterioration and Biodegradation Society. Session titles include: Fungal Deteriogen of Materials and their Conservation, Fungal Deteriogens and Food Spoilage, Impact of Fungal Deteriogens on Health, Economic Impact of Fungal Deteriogens. In addition there will be a number of posters.
Suggested reading: Microbial Biodegradation: Genomics and Molecular Biology and Mycology books

May 25 - 29, 2009. The 17th Congress of The International Society for Human and Animal Mycology 2009 (ISHAM 2009)
Keio Plaza Hotel, Shinjuku, Tokyo, Japan Further information
ISHAM2009 will address recent developments in medical, veterinary and environmental mycology with a focus on human and animal health. More than 30 symposia with distinguished speakers are planned, including keynote lectures, luncheon and evening seminars, and a new Poster Forum.
Suggested reading: Mycology Books

June 21 - 26, 2009 Mycotoxins and Phycotoxins
New London, NH, USA Further information
Gordon Research Conference. Presentation of leading-edge research on fungal, algal, and cyanobacterial toxins and the organisms that produce them. This multidisciplinary gathering will encompass the biology, ecology, genetics, chemistry and the public health and economic impacts
Suggested reading: Aspergillus: Molecular Biology and Genomics

July 19 - 24, 2009. 24th International Conference on Yeast Genetics and Molecular Biology
Manchester, UK Further information
Key conference themes will include: Cell Cycle and Morphogenesis, Control of Gene Expression, Genomes and Evolution, Protein Trafficking, Signal Transduction, Systems Biology, Yeasts as Cell Factories, Yeasts as Models for Ageing and Human Disease, Yeasts as Pathogens
Suggested reading: Mycology Books

August 26 - 29, 2009. Pasteur's Legacy: Yeast for Health and Biotechnologies (the 27th International Specialised Symposium on Yeast)
Institut Pasteur, Paris, France Further information

September 1 - 4, 2009. British Mycological Society annual scientific meeting
Dundee, UK Further information
The Fungal Cell. Including cellular organisation, metabolism and cellular regulation, fungal growth, morphogenesis and differentiation, and fungal interactions with other organisms including bacteria and plants.
Suggested reading: Mycology Books

October 18 - 21, 2009. 4th Trends in Medical Mycology TIMM4
Athens, Greece Further information
Organized jointly by the European Confederation of Medical Mycology (ECMM) and by the Infectious Diseases Group of the European Organization for Research and Treatment of Cancer (IDG-EORTC). The scientific programme will include plenary sessions on fungal infections in both immunocompromised and immunocompetent hosts led by an internationally renowned faculty giving plenary talks, round table sessions, and meet-the-expert meetings. The poster session will encourage one-to-one discussions between faculty, presenters and delegates. The meeting is designed for infectious disease specialists, haematologists, oncologists, transplant physicians, microbiologists, immunologists, dermatologists, intensivists and others with interest in medical mycology.
Suggested reading: Mycology Books

October 29 - 31, 2009. Mycology MasterClass IV
Hamilton Island, QLD, Australia Further information
Advanced medical mycology course for specialists and trainees in infectious diseases, microbiology, haematology and intensive care medicine and for laboratory scientists/technicians specialising in medical mycology.
Suggested reading: Aspergillus: Molecular Biology and Genomics

Labels: aspergillus, conference, fungal, fungi, mycology, yeast

Several pharmaceutical preparations containing probiotic yeast cells are commercially available and the beneficial properties of strains of some Saccharomyces spp are well documented. As well as providing nutritive value probiotic yeasts are generally resistant to gastrointestinal passage and are resistant to most antibiotics. A recent review by Zanello et al. entitled Saccharomyces boulardii effects on gastrointestinal diseases was recently published in the journal Current Issues in Molecular Biology.

Saccharomyces boulardii, a species of yeast, has been described as a biotherapeutic agent since several clinical trials displayed its beneficial effects in the prevention and the treatment of intestinal infections and in the maintenance of inflammatory bowel disease. All these diseases are characterized by acute diarrhoea. Administration of Saccharomyces boulardii in combination or not with an antibiotherapy has shown to decrease significantly the duration and the frequency of diarrhoea. Experimental studies have elucidated partially the molecular mechanisms triggered to improve the host health. The discovery of its anti-inflammatory and immuno-modulatory activities in correlation with the advances in the understanding of mucosal immunology opens a new field of perspectives in Saccharomyces boulardii therapeutic applications.

Free full text review at Saccharomyces boulardii effects on gastrointestinal diseases

Further reading on probiotic microorganisms: Lactobacillus Molecular Biology: From Genomics to Probiotics

Labels: probiotics, Saccharomyces, yeast