Day 2 of the Duke Mycology Symposium has wound to a close, [DAY 1 HERE] and I am sitting on my porch contemplating the afternoon’s lectures:
“Pathogen recombination during the amphibian Chytridiomycosis pandemic: Why change what’s working?”
A genetics perspective on Bd, a fungus responsible for widespread amphibian mortality. Apparently one of the factors in its spread is the abundance and transport of bullfrogs (raised for food) and xenopus frogs (used in medical research), which can carry the disease without being killed by it. The recent spread is caused by a single Bd strain which reproduces by cloning itself – it should therefor be genetically uniform. Yet, in practice Bd has a ‘dynamic genome’. This led to discussion led to mechanisms for genetic change without sex, such as mitotic crossover and gene conversion.
“Pathogenicity factors in the chytrid fungus and amphibian pathogen B. dendrobatidis”
Further discussion of Bd, this time from a molecular / genomic perspective. Perhaps the most interesting part was evidence that chytrids contain rhodopsin, a light-sensitive pigment.  I was also alerted to the existence of the 1000 fungal genomes project.
“Pleiotropic roles of the UPR pathway in Cryptococcus”
UPR is the unfolded protein response – when there are bits of proteins floating around inside a cell, it’s a bad sign. Maybe those proteins were torn apart by heat, or a toxin. This talk looked at the responses of Cryptococcus to the presence of the UPRs. In some cases, they release ‘chaperones’, proteins which help other molecules assemble correctly. Or, they might release dedegredation enzymes to clean up the mess. In extreme cases, they may even trigger apoptosis, a sort of cellular suicide.
“The adaptive value of Flo11‐dependent flocculation and adhesion in yeast”
Proteins on the surface of certain yeast cells act to let the cells stick together and form clusters, which then fall out of their liquid medium. The gene for this surface protein is under considerable epigenetic control – there was a really beautiful picture the speaker presented, in which genetically identical yeast cells nonetheless have different levels of gene expression. Additionally, this phenomenon is an example of the green beard effect.
“Fear the Titans: When bad yeast get worse”
Titan cells are variants of cryptococcus. as much as 20 times as large as typical cells. Continue reading