Category Archives: zygomycete

Escaping the dung pile quickly: Speedy Pilobolus spores

ResearchBlogging.orgSporangiophore discharge in the fungus <em/>Pilobolus kleinii captured with high speed video. In a paper appearing today in PLoS One, “The Fastest Flights in Nature: High-Speed Spore Discharge Mechanisms among Fungi” Nicholas Money and colleagues including 6 undergraduates and 3 graduate students, have measured the speed of flight of spores discharging from several Ascomycete and Zygomycete dung fungi including Pilobolus kleinii, Basidiobolus ranarum, Podospora anserina, and Ascobolus immersus. The team used high speed cameras that recorded at 250,000 frames per second and were able to capture spores being launched at 25 meters per second at accelerations of 180,000 g. The publication also provides multimedia including a video of the spore discharge slowed down and set to music. Nik and Mark Fisher both presented portions of the work at the Mycological Society of America 2008 meeting this summer and showed clips of these dramatic videos, so it was great to see this in print shortly following the meeting.

By way of the press release the major findings from this work show that

… the discharge mechanisms in fungi are powered by the same levels of pressure that are characteristic of the cells that make up the feeding colonies of fungi. Therefore, the long flights enjoyed by spores result not from unusually high pressure, but from the way in which explosive pressure loss is linked to the propulsion of the spores. There appear to be some similarities between the escape of the spores and the expulsion of ink droplets through nozzles on inkjet printers.

As Dr Money has described in a humorous and humble manner before in his Mr Bloomfield’s Orchard, some of the coolest and fundamental observations about spore flight and discharge, from Buller to the present, have come from simple and careful observations of fungi. In this case they have used a new tools of ultra high speed photography to capture events. Some of the previous work from the Money lab on this front include a demonstration that conidia are actively launched and rather than being passively released by low velocity airflow in the toxic indoor mold Stachybotrys (Tucker et al FGB 2007; free at PMC)

Yafetto L, Carroll L, Cui Y, Davis DJ, Fischer MWF,Henterly AC,, Kessler JD, Kilroy HA, Shidler JB, Stolze-Rybczynski JL, Sugawara Z, Money NP (2008). The Fastest Flights in Nature: High-Speed Spore Discharge Mechanisms among Fungi PLoS One, 3 (9) DOI: 10.1371/journal.pone.0003237

Papers on our desk

A quick post of some recent comparative genomics papers on our desk that are worth a look.

  • Khaldi N, Wolfe KH (2008) Elusive Origins of the Extra Genes in Aspergillus oryzae. PLoS ONE 3(8): e3036. doi:10.1371/journal.pone.0003036. This was a cool but somewhat controversal finding presented at Fungal Genetics last year.
  • Casselton, LA. Fungal sex genes – searching for the ancestors. doi: 10.1002/bies.20782. A review of recent findings about the Zygomycete MAT locus.
  • Soanes DM, Alam I, Cornell M, Wong HM, Hedeler C, et al. (2008) Comparative Genome Analysis of Filamentous Fungi Reveals Gene Family Expansions Associated with Fungal Pathogenesis. PLoS ONE 3(6): e2300. doi:10.1371/journal.pone.0002300
  • Lee DW, Freitag M, Selker EU, Aramayo R (2008) A Cytosine Methyltransferase Homologue Is Essential for Sexual Development in Aspergillus nidulans. PLoS ONE 3(6): e2531. doi:10.1371/journal.pone.0002531

Will a zygomycete help solve our energy woes?

I found the headline today, “Biofuels: Fungus Use Improves Corn-to-ethanol Process” and I was curious to find out what fungus they were talking about in the article. It turns out that researchers at Iowa State University found that Rhizopus microsporus is able to grow off part of the leftovers of ethanol production called thin stillage. The reason this is so exciting is explained below:

(Rhizopus sporangium, picture taking during PMB 110L @ UC Berkeley)

The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that’s produced. Those leftovers, known as stillage, contain solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.
The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds from corn and fermentation as well as enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.
The researchers added a fungus, Rhizopus microsporus, to the thin stillage and found it would feed and grow. The fungus removes about 80 percent of the organic material and all of the solids in the thin stillage, allowing the water and enzymes in the thin stillage to be recycled back into production.
The fungus can also be harvested. It’s a food-grade organism that’s rich in protein, certain essential amino acids and other nutrients. It can be dried and sold as a livestock feed supplement. Or it can be blended with distillers dried grains to boost its value as a livestock feed and make it more suitable for feeding hogs and chickens.

The idea of being more efficient by saving water and producing nutritious animal feed that can produce healthier animals that produce more meat is very interesting and worthwhile. But the article never mentions that many Rhizopus species are considered pathogens and R. microsporus when paired with Burkholderia rhizoxinia, a endosymbiont that produces rhizoxin, essentially becomes the pathogen responsible for rice seedling blight. Rhizopus also can cause serious mycoses in humans (The non squeamish can search for rhizopus mycoses on google).

I am curious if this Rhizopus has any endosymbionts that could be helping it grow on stillage or what other fungi that may not be potential pathogens might be out there that could also grow on the thin stillage.

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

Sex in fungi: MAT locus cloned from a Zygomycete

On the cover of this week’s Nature is a picture of Phycomyces blakesleeanus Nature Coverhighlighting the discovery of the MAT locus in this Zygomycete fungus from Alex Idnurm and Joe Heitman and colleagues. While it was previously known that Zygomycetes (the Orange lineage represented by R. oryzae in the tree below) mate, the specific locus has until now, never been discovered. The authors in this study identified the MAT locus through a sequence search looking for HMG-box genes knowing that these are found the Mating Type locus in Basidiomycetes and Ascomycetes. They confirmed the identity through a through set of experiments that included PCR, sequencing and crosses of (+) and (-) strains of P. blakesleeanus, and Southern blots.

Continue reading Sex in fungi: MAT locus cloned from a Zygomycete

Mucor circinelloides genome update

I recently heard through the grapevine that the Mucor ircinelloides genome 4X assembly was completed by JGI and a BLAST server is available if you contact the authors. Mucorales (previously Zygomycota which is not monophyletic) includes previously sequenced Rhizopus oryzae and Phycomyces blakesleeanus which we’ve blogged about before.

Continue reading Mucor circinelloides genome update

Fungal tree of life papers

Lots of papers in Mycologia (subscription required) this month of different groups analyzing the fine-scale relationships of many different fungal clades using the loads of sequences that were generated as part of the Fungal Tree of Life project.

Some highlights – there are just too many papers in the issue to cover them all. As usual with more detailed studies of clades with molecular sequences we find that morphologically defined groupings aren’t always truly monophyletic and some species even end up being reclassified. Not that molecular sequence approaches are infallable, but for many fungi the morphological characters are not always stable and can revert (See Hibbet 2004 for a nice treatment of this in mushrooms; subscription required).

  • Meredith Blackwell and others describe the Deep Hypha research coordination network that helped coordinate all the Fungal Tree of Life-rs.
  • John Taylor and Mary Berbee update their previous dating work with new divergence dates for the fungi using as much of the fossil evidence as we have.
  • The early diverging Chytridiomycota, Glomeromycota, and Zygomycota are each described. Tim James and others present updated Chytridiomycota relationships so of which were only briefly introducted in the kingdom-wide analysis paper published last year.
  • There is a nice overview paper of the major Agaricales clades (mushrooms for the non-initiated) from Brandon Matheny as well as as individual treatment of many of the sub-clades like the cantharelloid clade (mmm chanterelles…) .
  • Relationships of the Puccinia clade are also presented – we blogged about the wheat pathogen P. graminis before.
  • A new Saccharomycetales phylogeny is presented by Sung-Oui Suh and others.
  • The validity of the Archiascomycete group is also tested (containing the fission yeast Schizosaccharomyces pombe and the mammalian pathogen Pneumocystis) and they confirm that it is basal to the two sister clades the euascomycete (containing Neurospora) and hemiascomycete (containing Saccharomyces) clades. However it doesn’t appear there are enough sampled species/genes to confirm monophyly of the group. There are/will be soon three genome sequences of Schizosaccharomyces plus one or two Pneumocystis genomes – it will be interesting to see how this story turns out if more species can be identified.

This was a monster effort by a lot of people who it is really nice to see it all have come together in what looks like some really nice papers.

Fungal Genetics 2007 details

I’m including a recapping as many of the talks as I remember. There were 6 concurrent sessions each afternoon so you have to miss a lot of talks. The conference was bursting at the seams as it was- at least 140 people had to be turned away beyond the 750 who attended.

If there was any theme in the conference it was “Hey we are all using these genome sequences we’ve been talking about getting”. I only found the overview talks that solely describe the genome solely a little dry as compared to those more focused on particular questions. I guess my genome palate is becoming refined.

Continue reading Fungal Genetics 2007 details

Phycomyces Genome Release 1

phycomycesThe JGI has released the Phycomyces blakesleeanus genome. This represents the second Zygomycete genome sequence that has been released in addition to Rhizopus oryzae that was released by the Broad Institute last year. We are now getting a better look at the basal fungal genomes including the Chytrids and Zygomycetes. Much more on specifics of Phycomyces biology and history are on this site run by the group organizing the genome analysis.

I find one of the most interesting things about P. blakesleeanus is its phototropism. We know light sensing is controlled, in part, by the gene white-collar 1. A homolog of this gene in Neurospora crassa is involved as an oscillator circadian rhythm. Of course many more genes are involve in pathways for light sensing including some really old proteins like phytochromes.

There will be a lot of cool analyses to do with this genome beyond phototropism. I am looking forward to seeing what gene families are unique and expanded in this species relative to the other zygomycete. It also looks like it is quite intron rich much like the Basidiomycetes, further supporting the idea that fungi had intron rich ancestors.