I gave a lecture on animal-fungal symbionts and parasites this week so was doing more reading of recent literature on insect-fungi associations. A couple of quick notes worth sharing.
Ophiocordyceps unilateralis was the parasite of the day last week and includes a description of an interesting recent paper looking at the consistency of the symptoms of zombie ants. The article also mentions Carl Zimmer’s post on the same paper in more detail.
You of course have seen the very cool electronic/online Cordyceps monograph at cordyceps.us from Joey Spatafora’s lab?
The genome of Cordyceps militaris was sequenced by researchers at the Chinese Academy of Sciences. They find a reduced copy numbers of many gene families suggesting to the authors that the specialized ecology of the fungus may have limited the need for expanded gene families. The do find expanded copy numbers of metalloproteases – a finding we have also seen in human and amphibian associated pathogens as well as by the authors who looked at the insect associated fungus Metarhizium. There is also a reduction in cutinases and genes related to degrading plant cell walls similar to findings in the human associated pathogens Coccidioides suggesting similar genomic routes to specializing on an animal host from a generalist. They also found that this fungus is heterothallic based on genomic identification of the MAT1-1 locus. There are several more interesting findings in the paper including expression profiling of fruiting body via RNA-Seq.
Zheng, P., Xia, Y., Xiao, G., Xiong, C., Hu, X., Zhang, S., Zheng, H., Huang, Y., Zhou, Y., Wang, S., Zhao, G., Liu, X., St Leger, R., & Wang, C. (2011). Genome sequence of the insect pathogenic fungus Cordyceps militaris, a valued traditional Chinese medicine Genome Biology, 12 (11) DOI: 10.1186/gb-2011-12-11-r116
A critical part of understanding and documenting the diversity is formal descriptions of species and their relatives. This can be a laborious task and is usually captured in the form of a monograph of a species where a group of species are described in careful detail along with the phylogenetic relationships of them. This has served as the basis for documentation of the the natural history and morphological descriptions of species. The information is typically presented in the form of a book that goes to a library or your shelf which can be pulled down and poured over when trying to determine traits for a group of organisms. Books are great but sharing images and the
Ryan Kepler, a PhD student at Oregon State, is writing a monograph about the ever so cool Cordyceps fungi which have intimate and quite manipulative relationship with insects. However, he’s doing it as an electronic monograph that he is publishing on the web. This is a great way to share this technical and visual information. By publishing it online he is making it searchable and so that it can be a living document that can be updated over time. He’s also willing to publish it as he goes along so the current version is a starting point, but will continue to mature as he completes his PhD thesis work and has input from other experts in the field. I really like that the is publishing it early on and truly embracing an open science approach to presenting his descriptions of the species and their relationships. This is akin to other efforts putting information about species on the web, from the Encyclopedia of Life to Mushroom observer, but I really like that this is a site dedicated to capturing the expert level information that Ryan is gathering as part of this thesis in a searchable and interactive form.
Cordyceps are an interesting group of fungi not only because of their insect association, but their variety of colors and morphologies. The ability to manipulate their insect hosts also suggests a wide variety of secondary metabolites are probably produced by these fungi to enable them to change behavior of infected individuals.
Will be great to see this resource mature and also additional monographs and species descriptions to embrace an online and freely available form. I suspect there could be a (tiny) market for better web software here for making this easier so that one doesn’t have to be or have an expert web development team to deploy these for individual projects.