I photographed these Psilocybe cubensis to illustrate what I think is herbivory (and I'm always prepared to be wrong). A chemist colleague of mine was chatting about the origin of psilocybin to deter insects, but I think that hypothesis requires testing.
Maybe knowledge of who eats Psilocybe now can shed light on why psilocybin evolved. Whether it was a deterrent or an attractant to help spread spores is something I would give anything to know :). A complex gene pathway that has evolved convergently and been acquired horizontally indicates there is an evolutionary advantage to produce psilocybin. I've also wondered whether cows mistakenly hoover up stray mushrooms from long grass. I can imagine they would, and a farmer thought his cows went 'loopy' every so often. Surely humans aren't the only beneficiaries of psilocybin.
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All this talk about haploid stages, I thought I should illustrate it for y'all. Mushrooms (n+n) are the site of recombination, which occurs after nuclei fuse in the basidium (karyogamy to make a diploid nucleus, 2n). Basidiospores are haploid (n), containing one recombinant nucleus.
I use a single basidiospore to grow cultures to make the genetic analyses easier with only one copy of each chromosome instead of two in a dikaryon (n+n) or diploid (2n). I've added mating genes in Basidiomycota to the figure; the homeodomain locus (HD), which usually has two genes, and the pheromone/receptor locus. Alleles of all genes at these loci must differ for a compatible cross. I'll cover this more when I've annotated the mating genes in our genomes of P. cubensis and P. subaeruginosa. Thank you to AGRF for the high quality genomic data that we have since assembled. Each sample had 19–27 million reads (about 6–8 Gb of data). I was worried that I didn't sequence Psilocybe, however, our rDNA contigs are a perfect match for P. subaeruginosa and P. cubensis (pictured above). Phew. (The resolution of the tree is atrocious, if you're desperate to see the taxon selection, there is a pdf here). My next worry was that I had contaminated haploid cultures with dikaryotic cultures. What a relief, everything that is meant to be haploid, was haploid. The below figure shows that the one dikaryon (essentially a diploid) we sequenced was a much worse assembly than our haploids. I'll use this information to only sequence haploids in the future. Next step is to improve these assemblies with some long reads from PacBio. Stay tuned for updates on what we pull out from these genomes in the next few weeks... with a decent annotation, we may already be able to make a case that P. cyanescens is con-specific with P. subaeruginosa, depending on their similarity. Genome assemblies for Psilocybe cubensis (first three on the left) and P. subaeruginosa. The circle size is proportional to genome size, and number of contigs is centred in circles. The far right assembly was a dikaryotic culture of P. subaeruginosa, all other assemblies were haploid. We want the number in the circle to be as small as possible to reflect the number of chromosomes. |
Designer Shrooms @ Funky Fungus on 1st July 2023
I started a gig at Funky Fungus as Chief Scientific Officer to make designer shrooms Our research on Psilocybe
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