Category Archives: pathogens

Coprinus on the heart?

Here’s a fungal infection you don’t hear much about. One of the fungi we work on, a model for mushroom development as it can be fruited in the lab is Coprinopsis cinerea (previously named Coprinus cinereus). C. cinerea is a saprobric coprophillic fungus so it is usually found on dung.  Although rare in human infections there are a few reports in immunocopromised patients.  Below is an abstract describing isolation of C. cinerea from an implanted heart valve from a pig. This definitely not its typical habitat and Coprinus growing in yeast form I’m sure I’ve really heard of either.  Would be great to see if the clinical strains are still sexually competent and/or are significantly different in other ways (growth rate, resistance to drugs and oxidative stress) from the wild or laboratory strains.

A 77-year-old female initially presented with symptomatic mitral valve stenosis involving a bioprosthesis that had been implanted 8 months earlier for myxomatous mitral valve disease and severe valvular regurgitation. The patient was taken for a second mitral valve replacement due to stenosis. Intraoperatively, the bioprosthetic mitral valve was noted to have an unusual clot-like mass on the atrial side. Initial fungal smears were positive for yeast stains, and pathology revealed extensive colonization by thick filamentous fungus with apparent true hyphae, pseudohyphae, and yeast forms. The fungus was identified as Hormographiella aspergillata, the asexual form of Coprinus cinereus, a common inky cap mushroom that grows in the lawn.

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Ireland’s blight and Puccinia update

Hyphoid logic points out that it is appropriate to discuss about the oomycete Phytophthora infestans on St. Patrick’s Day and mentions a NYT article “The fungus that conquered Europe” that is worth a look.

It is also worth thinking about another blight, well rust, that is spreading through the middle east and could threaten wheat crops worldwide. New Scientist has excellent coverage of Puccinia graminis strain Ug99 which is spreading faster than expected due to a cyclone that spread the rust spores into Iran two years earlier than expected.

Related posts from last year. “Fungus could cause a food shortage”, “Puccinia black stem rust disease spreading”

Some links

I’ve been too busy to post much these last few days, but here are a few links to some papers I found interesting in my recent browsing.

Schmitt, I., Partida-Martinez, L.P., Winkler, R., Voigt, K., Einax, E., Dölz, F., Telle, S., Wöstemeyer, J., Hertweck, C. (2008). Evolution of host resistance in a toxin-producing bacterial–fungal alliance. The ISME Journal DOI: 10.1038/ismej.2008.19

LEVASSEUR, A. (2008). FOLy: an integrated database for the classification and functional annotation of fungal oxidoreductases potentially involved in the degradation of lignin and related aromatic compounds. Fungal Genetics and Biology DOI: 10.1016/j.fgb.2008.01.004

Shivaji, S., Bhadra, B., Rao, R.S., Pradhan, S. (2008). Rhodotorula himalayensis sp. nov., a novel psychrophilic yeast isolated from Roopkund Lake of the Himalayan mountain ranges, India. Extremophiles DOI: 10.1007/s00792-008-0144-z

Cryptococcus species deliniation What delineates species boundaries in fungi? Much work has been done on biological and phylogenetic species concepts in fungi. Some concepts are reviewed in Taylor et al 2006 and in Taylor et al 2000, and applications can be seen in several pathogens such as Paraccocidiodies, Coccidioides, and the model filamentous (non-pathogenic) fungus Neurospora.

A paper in Fungal Genetics and Biology on species definitions in Cryptococcus neoformans from multi-locus sequencing seeks to provide additional treatment of the observed diversity. A large study of 117 Cryptococcus isolates were examined through multi-locus sequencing (6 loci) and identified two monophyletic lineages within C. neoformans varieties that correspond to var. neoformans and var. grubii. However within the C. gattii samples they identified four monophyletic groups consistent with deep divergences observed from whole genome trees for two strains of C. gattii, MLST, and AFLP studies. By first defining species, we can now test whether any of the species groups have different traits including prevalence in clinical settings and in nature.

BOVERS, M., HAGEN, F., KURAMAE, E., BOEKHOUT, T. (2007). Six monophyletic lineages identified within Cryptococcus neoformans and Cryptococcus gattii by multi-locus sequence typing. Fungal Genetics and Biology DOI: 10.1016/j.fgb.2007.12.004

Phytopathogenic Fungi: what have we learned from genome sequences?

ResearchBlogging.orgA review in Plant Cell from Darren Soanes and colleagues summarizes some of the major findings about evolution of phytopathogenic fungi gleaned from genome sequencing highlighting 12 fungi and 2 oomycetes. By mapping evolution of genes identified as virulence factors as well as genes that appear to have similar patterns of diversification, we can hope to derive some principals about how phytopathogenic fungi have evolved from saprophyte ancestors.

They infer from phylogenies we’ve published (Fitzpatrick et al, James et al) that plant pathogenic capabilities have arisen at least 5 times in the fungi and at least 7 times in the eukaryotes. In addition they use data on gene duplication and loss in the ascomycete fungi (Wapinski et al) to infer there large numbers of losses and gains of genes have occurred in fungal lineages.

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Stagonospora nodorum genome published

Blogging about Peer-Reviewed ResearchThe Stagonospra nodorum (teleomorph Phaeosphaeria nodorum) genome is now published in Plant Cell, “Sequencing and EST Analysis of the Wheat Pathogen Stagonospora nodorum”. The paper describes the sequencing and analysis of this Dothideomycete fungus. The analyses included identifying genes likely involved in pathogenecity such as PKS and NRPS genes and enabled the discovery of new genes like ToxA.

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Saccharomyces strain sequencing

Blogging on Peer-Reviewed ResearchWhile many strains of S. cerevisiae are being sequenced, a single strain, YJM789, isolated from the lung of an AIDS patient was sequenced a few years ago at Stanford and published this summer. The genome was described in a paper entitled “Genome sequencing and comparative analysis of Saccharomyces cerevisiae strain YJM789”.

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This fungus will trap you (if you are a Nematode)

Blogging about Peer-Reviewed ResearchFungi, like most organisms, take an active role in finding food for survival. When thinking about hostile takeovers by fungi, one probably thinks about mycelia growing towards nutrients, rotting plant matter, the ability to extract nutrients from a living host, or perhaps producing toxins or secondary metabolites that can affect the host. However, some fungi can take an even more active role and trap their animal hosts (when that animal isn’t much bigger than you). A paper from earlier this year on “Evolution of nematode-trapping cells of predatory fungi of the Orbiliaceae based on evidence from rRNA-encoding DNA and multiprotein sequences” describes the evolutionary history of a group of fungi able to trap and eat nematodes. Nematode trapping fungi have been investigated experimentally since at least the 30s (Drechsler, Mycologia. 1937, Drechsler, J Wash Acad Sci. 1933), and some more recent studies of the relationship of the groups (Rubner, Studies in Mycology. 1996).

In the recent PNAS paper, the authors used multi-locus sequencing to reconstruct a phylogeny and history of large group of carnivorous fungi and reconstruct the ancestral history the prey trapping mechanism of either through constricting rings or adhesive traps. They were able to reconstruct the likely order of the evolutionary steps needed to make the stalk and trapping cells. They found that the most common type of trap, an Adhesive Network, was the earliest evolved trap.

Some movies also demonstrate how these fungi make their living.