A Fungal Genetics 2007 summary. Wow. What a meeting! I am still exhausted and not just because of the very late Saturday night dancing at the close of the conference. I will just say anyone who thinks scientists are boring people should witness the passion researchers have for their science and in sharing it with other people. Not to mention that some know how to put on their dancing shoes and let loose. Because of the atmosphere at the Asilomar conference center, it really did feel like I was at a super fun science camp that culminated with a rock band and dancing in the big hall.
I am also digesting the science from the talks and social interactions with a variety of people enthusiastic about mycology, genomes, and evolution (which could be a conference unto itsself). There were presentations on a lot of really great topics, from symbiosis between mycorhizal fungi and plants (Laccaria bicolor) to cell wall structure in Cryptococcus. I got to meet so many people who are making an impact in the fungal community both in their research and in the resources provide online. I will try and re-cap so I can remember everything I saw.
Self and non-self recognition is important for fungi when hyphae interact fuse if they should compartmentalize and undergo apoptosis to kill the heterokaryoton or exchange nutrients. This process is part of cell defense and to limit to the movement of mycoviruses.
A paper in PLOS ONE describes the Genesis of Fungal Non-Self Repertoire. This kind of work goes on down the hall from us as well in the Glass lab among others. This recent paper describes het genes, which contain WD40 repeats and different combinations of these help control specificity. There is of course a diverse literature on this subject especially in Neurospora, and I’m not reviewing it here, but it is an imporant process in understanding how fungi interact with their environment.
We’re at Asilomar mtg for Fungal Genetics 2007. We’ll try and blog a bit about the interesting talks and data.Â I’m curious how many fungal geneticists are in fact reading blogs like these and if this medium will work for idea dissemination.
The Candida clade of Hemiascomycete fungi have received much attention from funding bodies so that many genomic and experimental resources are available address questions of pathogenecity and industrial applications of these species.
The Candida genus
Traditionally, species of yeasts that were thought to be asexual were given the genus name Candida. This has lead to Candida being a sort of taxonomic rubbish bin as this system of classification breaks down when asexuality arises more than once (creating homoplasy). For example, the asexual Candida glabrata is found within the Saccharomyces clade when molecular phylogenetics is applied. The problem lies in that many of these species appear very similar visually and microscopically and so there had not been enough phylogenetically informative phenotypic characters to easily classify them further. With the use of molecular phylogenetics the classifications have been improved as shown in several studies, however we retain the historical nature of the genus and species names for these organisms for the time being even though the phylogenetic diversity of species in the “genus” is much broader than other genus-level classifications. It will be interesting to see whether taxonomic proposals like PhyloCode or traditional revisions of the species names will provide new names for the group.
The Candida Genome Database (CGD) sister to the Saccharomyces Genome Database (SGD) provides resources for phenotype and sequences related to human commensal and dimorphic fungus Candida albicans. A recent paper by Arnaud et al describes the resources that are available through their website. An essentially completed C. albicans diploid genome with curated gene models and annotations provides an essential resource for this model pathogenic system. In addition to the SC5314 strain of C. albicans the white-opaque (WO) strain can switch between different colony morphologies – white and smooth or gray and rod shaped.
The Saccharomyces Genome Database has deployed a wiki for gene annotation from the community.Â This should be an interesting experiment in how information can flow from the community into these databases.
Cliff Zeyl and Sally Ottopresent a nice review on research from the Kruglyak lab regarding evidence that Saccharomyces is primarily a selfer in nature as it outbreeds very infrequently (once in 50,000 generations). The implications of this work has relevance on the importance of sexual reproduction and recombination in natural populations.
A paper by Martin Aslett and Val Wood indicate that the fission yeast community is approaching 100% coverage of a GO annotation for every gene in the S. pombe genome. Only Ashbya gossypii has a smaller genome in the fungi (see a recent paper on Ashbya annotation database) and doesn’t yet have complete GO coverage. This is quite remarkable and a great dataset for studies in S. pombe and all fungi.
My quick predictions of genes a closely related species, S. japonicus, has more than twice as many genes as S. pombe (but be over-prediction by ab initio predictors). Taken in comparison to many other fungi, S. pombe represents a streamlined and reduced genome which probably occured indepdently from reduction in the Hemiascomycetes.
The public release of the Batrachochytrium dendrobatidis automated annotation from the Broad/FGI has been made available.
“This project is part of the Fungal Genome Initiative at the Broad Institute and was funded by NHGRI. This release contains a set of 8,794 predicted genes, BLAST databases, precomputed BlastX and HMMer analyses, alternative gene predictions, tRNA predictions, and RFAM features.
A paper in PLoS Genetics studied what happens when individual chromosomes of S. cerevisiae are replaced with a homologous copy its sister species, S. paradoxus. Previous work from Ken Wolfe’s lab interpreted the differential loss of genes after the whole genome duplication in the Saccharomyces lineage played a role in speciation among the yeast species. Surprisingly (or not, depending on how you interpret the previous work) Greig did not find any lethality in haploid F1 offspring from a diploid synthetically constructed individuals. Certainly this is not the last word but it represents a nice experimental screen to identify interacting genotypes. What would be interesting in followup work would be more subtle dissection of epistatic interactions among the genes on the different chromosomes to score phenotypes other than complete inviability. This might help understand what pathways are operating differently.