Psilocybe
1. Classification
a. Higher order taxa
The genus Psilocybe is of the domain Fungi, the phylum Basidiomycota, the class Agaricomycetes, the order Agaricales, and the family Strophariaceae (1).
2. Description and significance
The genus Psilocybe composes the fungi known as “magic mushrooms.” These are psychedelic mushrooms that produce the metabolite psilocybin (2). Members of this genus are distributed worldwide and are able to grow in most biomes. The greatest species diversity is found in the neotropic zone, specifically Mexico, while other important members are found in the forests of Japan and China (2,3). This genus is important because of the increasing use of its hallucinogenic molecule as a recreational psychedelic drug, as well as its potential use in alleviating the symptoms of certain mental illnesses, such as anxiety, depression, and obsessive-compulsive disorder (4,5). How and why these mushrooms make this molecule is unknown, and current research continues to focus on its effects as opposed to its purpose in the fungi.
3. Genome structure
The DNA genome of Psilocybe cubensis has been sequenced, and sequencing libraries have been constructed (6). The genome contains 32 contigs, and has a total length of 46,603,414 base pairs. The GC content of the total genome is 46.09%, and the AT content is 53.91% (7). The noncoding sequence of the genome is 26,985,414 base pairs in length. It has a GC content of 43.24% and an AT content of 56.76% (7). After being annotated using FunAnnotate, the genome was found to contain 13,478 genes (6).
The genera Psilocybe and Panaelous have many similarities in their rRNA sequences (8,9). The ITS-1 region of Psilocybe varies from roughly 295 to 350 base pairs. In comparison, the genus Panaeolus, shows little variation with a range of about 20 base pairs (8).
A common feature among species in the Psilocybe genus is that all the necessary anabolic, transport, and regulatory genes used in metabolite biosynthesis are organized into genes that may have been acquired via horizontal gene transfer. The psilocybin pathway in particular may have been acquired because of the horizontal gene transfer of a gene cluster (10). Horizontal gene transfer of gene clusters also further supports that the Psilocybe genus is closely related to Panaeolus, another fungi genus that has species that also contain the hallucinogen psilocybin (10).
4. Cell structure
Psilocybe mushrooms are gilled mushrooms that are typically small with brown caps (11, 12). They produce basidiospores that have a non-angular shape with two layers detectable through light microscopy (13). Dormant basidiospores have clearly defined pores on their nuclei, a well defined plasma membrane, mitochondria, lipid bodies, and ribosomes. One of the defining features of the genus Psilocybe is the thickness of the basidiospores they produce. However, Psilocybe spores do not have an endoplasmic reticulum (14). When these spores are germinated with a hot water extract of horse dung, the only differences seen are an increase in small vacuoles and electron density in the germ tubes (14).
5. Metabolic processes
Psilocybe acquire energy by breaking down organic molecules, and therefore, it is a chemoorganoheterotroph. Psilocybe, like other fungi, excrete the enzymes onto the material that is to be metabolized and ingest the material once it is hydrolyzed (15). Members of the genus Psilocybe synthesize the hallucinogenic indole alkaloid molecule (Figure 2) (8). The difference in the structure of this molecule (either psilocybin or psilocin) between some members of the genus is due to phosphorylation (psilocybin) or hydroxylation (psilocin) at the R position (8). Psilocybin contains an indole-amine ring in its structure (Figure 2) and is derived from tryptophan, the only amino acid with an indole-amine ring. Tryptophan is then decarboxylated to tryptamine (16). After tryptamine is produced, it is methylated two times to become DMT, which is hydroxylated to psilocin. Psilocin is then phosphorylated to synthesize psilocybin (16).
Oral consumption of psilocybin results in dephosphorylation of the molecule, primarily by alkaline phosphatase, in the intestine and liver. The dephosphorylated form of psilocybin (psilocin) is responsible for psychotropic effects in humans (17).
Psilocybe have a unique blue-staining reaction that happens after the fruit body of the Psilocybe is damaged. This reaction occurs when psilocybin is oxidized after the fruit body becomes exposed to oxygen and water. The extent to how much bluing occurs depends on the concentration of psilocin in the organism (18).
6. Ecology
Psilocybe play a part in early decay of wood (8). Via horizontal and vertical gene transfer, the genus also developed dung-decaying properties (8). Psilocybin modulates insect behavior by acting as a neurotransmitter agonist, affecting the feeding behavior of social insects and invertebrates like termites. Several wood-decaying fungi, like Psilocybe, have repellents and toxins that prevent termites from feeding on wood, which provides a competitive fitness advantage (8).
The Psilocybe genus is found all over the world, but the neotropic ecozone contains the most diversity (2). One member of the genus, P. semilanceata, exists in both cool climates like the coasts of Northern America and Europe and warm areas like India and Chile. However, P. semilanceata’s preferred habitat is grassy fields and meadows that have been fertilized by animal feces (2). P. semilanceata acts as a saprobe by gaining nutrients from the decaying grass roots, unlike P. cubensis which feeds and lives on top of the dung (2).
7. Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
8. Current Research
Include information about how this microbe (or related microbes) are currently being studied and for what purpose
9. References
It is required that you add at least five primary research articles (in same format as the sample reference below) that corresponds to the info that you added to this page. [Sample reference] Faller, A., and Schleifer, K. "Modified Oxidase and Benzidine Tests for Separation of Staphylococci from Micrococci". Journal of Clinical Microbiology. 1981. Volume 13. p. 1031-1035.
