Tag Archives: cryptococcus

Postdoc positions at Duke University & MMTP

Postdoc positions in the Heitman lab and through the Molecular Mycology Training Program at Duke University, NC State, and University of North Carolina are available as of December 1, 2014.

HeitmanImageThe Heitman lab at Duke University is seeking Postdoctoral Fellow applicants. The lab focuses on molecular determinants of development and virulence in the pathogenic basidiomycetes Cryptococcus neoformans and Cryptococcus gattii with complementary studies in both model and pathogenic fungi including Cryptococcus amylolentus, Filobasidiella depauperata, Cryptococcus heveanensis and other related basidiomycetes including Kwoniella and Malassezia species, species from the Candida pathogenic complex (C. albicans, C. lusitaniae), and the zygomycete Mucor circinelloides.

Areas of research interest include:

  • modes and impact of unisexual and sexual reproduction
  • structure, function, and evolution of the mating type locus
  • calcineurin in fungal virulence and as a novel antifungal drug target
  • comparative fungal genomics of a species cluster of human fungal pathogens
  • molecular networks that orchestrate infection of the host and development
  • RNAi based pathways operating during mitotic and sexual development and epimutational gene silencing
  • mechanisms of action of natural products and antifungal drugs

Applications should send pdfs of curriculum vitae, reprints/preprints, a statement of research accomplishments and interests, and letters of recommendation to Joseph Heitman at heitm001@duke.edu.

Myco-bio-diesel

Previously I posted on an article on making biodiesel using the fungus Gliocladium roseum. Here is a new study reporting conversion of lipids to biodiesel using the basidiomycete Cryptococcus curvatus. There has been also other progress in this area where Mucor circinelloides can also be used to produce oils suitable for biodiesel production as reported in the paper and the press release – though it is a pathogenic fungus with interesting spore size dimorphism.

Thiru M, Sankh S, & Rangaswamy V (2011). Process for biodiesel production from Cryptococcus curvatus. Bioresource technology PMID: 21930373

Origins and evolution of pathogens

ResearchBlogging.org An article in PLoS Pathogens by Morris et al describe a hypothesis about the evolution and origins of plant pathogens applying the parallel theories to the emergence of medically relevant pathogens. The authors highlight the importance of understanding the evolution of organisms in the context of emerging pathogens like Puccinia Ug99 for our ability to design strategies to protect human health and food supplies.  Both bacterial and fungal pathogens of plants are discussed but I (perhaps unsurprisingly) focus on the fungi here. Continue reading Origins and evolution of pathogens

Jelly fungus Tremella genome available at JGI

Tremella mesenterica (from K. Findley)
Tremella mesenterica (from K. Findley)

The Tremella mesenterica genome portal is now live at the JGI. The genome is ~28Mb and the JGI annotation group predicted 8,313 genes, a significantly larger number of peptides predicted for C. neoformans (~7000; 18Mb genome) which may represent new and interesting genes or aspects of gene loss in the Cryptococcus yeast lineage.

Tremella is a Basidiomycete jelly fungus and an interesting study system from the perspective of discovery of novel lignin degrading enzymes.  It also occupies an interesting phylogenetic position being an outgroup to the human pathogenic yeast Cryptococcus neoformans and C. gattii. Comparative genomics on this system may also provide insight into the interesting evolution of the large mating-type locus that was formed through various rearrangements resulting in conversion from a tetrapolar to biopolar mating system.

Tremella may also be an important source of understanding wood degradation and how it differs in jelly fungi from the more distantly related Agaricomycotina (mushroom forming). The fungus is reasonably easy to grow in the laboratory and also to collect from nature. It can handle some desiccation to survive during a dry period only to swell up after  moisture is available.  It is also called Witch’s butter and Tom Volk has a summary of its features on his FOTM page.  It can often be confused with a phylogenetically distinct jelly fungus named Dacyromyces, usually the differences can be best be determined microscopically.  See what kinds of Tremella people have been finding at the Mushroom Observer.

See also

    On the content of (petri plate) Media

    ResearchBlogging.orgAn avid reader pointed out that I was not entirely thorough in describing that we don’t enough about the V8 agar media that is used to induce mating in Cryptococcus. In fact a great deal of work on mating in this fungus had focused on identifying what pathways are induced by V8 agar that induce mating.  It was shown that inositol stimulates mating through use of defined media containing inositol (Xue et al, 2007).  This paper interestingly explores plant-fungal interactions and Cryptococcus suggesting that mating may occur preferentially on plants in cases where inositol is abundant.

    It is also worth noting that V8 media contains a high level of copper ions and it was also pointed out to me that Jef Edman’s lab showed that melanin mutants have mating defects, and both phenotypes are suppressed by copper. And more recently (Lin et al, PLOS Genetics 2006) found that alleles of the Mac1 copper regulated transcription factor are a QTL influencing hyphal growth and melanin production, and showed that copper can enhance hyphal growth.

    So the role of copper and interplay with V8 agar media and how this induces mating is actually quite known.

    C XUE, Y TADA, X DONG, J HEITMAN (2007). The Human Fungal Pathogen Cryptococcus Can Complete Its Sexual Cycle during a Pathogenic Association with Plants Cell Host & Microbe, 1 (4), 263-273 DOI: 10.1016/j.chom.2007.05.005

    New species of Cryptococcus found in seawater

    A paper in IJSEM describes a new species in the Cryptococcus basidiomycete yeast lineage. The name is proposed as Cryptococcus keelungensis sp. nov. for a strain isolated from the sea surface microlayer. Its identity as a Cryptococcus sp was determined by sequencing of 26S rDNA D1/D2 and ITS loci and molecular phylogenetics. This is quite diverged from the human pathogen Cryptococcus neoformans and C. gattii as the new species falls in the order Filobasidiales while C. neoformans is classified in the order Tremellales. Interestingly, based on the phylogeny in the paper it seems to be relatively close to newly discovered Cryptococcus himalayensis.

    See also:

    C.-F. Chang, C.-F. Lee, S.-M. Liu (2008). Cryptococcus keelungensis sp. nov., an anamorphic basidiomycetous yeast isolated from the sea-surface microlayer of the north-east coast of Taiwan INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 58 (12), 2973-2976 DOI: 10.1099/ijs.0.65773-0

    Updated Cryptococcus serotype A annotation

    SEM of clamp cell, yeast cells and sexual spore chains. Courtesy R. Velagapudi & J. Heitman

    A new and improved annotation of Cryptococcus neoformans var grubii strain H99 (serotype A) has been made available in GenBank and the Broad Institute website. This update is collaboration between several groups providing data and analyses and the genome annotation team at the Broad Institute.

    Some changes noted by the Broad Institute include:

    “This release of gene predictions for the serotype A isolate Cryptococcus neoformans var. grubii H99 is based on a new genomic assembly provided by Dr. Fred Dietrich at the Duke Center for Genome Technology. The new assembly consists of 14 nuclear chromosomes and a single 21 KB mitochondrial chromosome, and has resulted in a reduction of the estimated genome size from 19.5 to 18.9 Mb. Improvements in the assembly and in our annotation process have resulted in a set of 6,967 predicted protein products, 335 fewer than the previous release.”

    Odds and ends

    Boletus

    Fungi on Science Friday

    NPR’s Science Friday covered fungi with several myco-luminaries on the radiowaves including:

    The show also speaks with Gavin Sherlock on recently published work on the origins of lager yeast.

    Bats beware of white nose

    An outbreak of a fungal infection called “white-nose syndrome” is killing bats in the Northeastern US.  This New Scientist article mentions the outbreak briefly and an NPR story and recent Boston Globe story also gives it some coverage.  Sounds like we still don’t know much about the causal agent or how it is killing the bats at this time, but some researchers, including Elizabeth Buckles at Cornell University, Vishnu Chaturvedi at NY State Dept of Health, and Jon Reichard at Boston University are working on it.

    This is of course old news if you read what Hyphoid Logic has been saying.

    That there is a previously undescribed cold loving fungus sounds very interesting, there have been some recent discoveries of psychrophilic fungi like Cryptococcus laurentii and Rhodotorula himalayensis so it would be interesting to learn more when the researchers publish some of these results.

    Some more links

    Thanks Kathyrn B for reminder about this story.