User:CameronMroz/sandbox

Definition:

Ergot fungi are a collection of around 59 ascomycete fungi species which fall within the Claviceps genus. They are pathogenic fungi, infecting around 600 species of grasses, grain, and cereal. They are well known for the production of toxic ergot-alkaloids in their fruiting bodies, which can cause a series of convulsive, gangrenous, and enteroergotic symptoms to mammals.

Biology + life cycle:

The structure of Claviceps fungi is related to their life cycle. They initially begin as windborne ascospores, gliding with the wind with the goal of landing on a viable host. There are several conditionals that must be satisfied in order for these spores to colonize their hosts: these are temperature, humidity, and life stage of the host Once found, they will attach to the pistil of the young, flowering plant. Their hyphae then imitate a male pollen grain and penetrate the ovaries of the plant. The hyphae then grows into and hijacks the vascular bundle. They specifically avoid growing deeper into the plant; they remain on the flower and harvest the nutrients of the plant.

Growth: As time goes on, they will grow sphacelial stroma (asexual fruiting bodies of Ergot) on the flower ovaries, which produce and release asexual spores. These are secreted from the sphacelial stroma in a sugary viscous fluid often called honeydew. These spores can then be transmitted by rain splash, head-to-head contact, or insect vectors to other nearby hosts. This process will continue until the Ergot begins a switch to producing sclerotia, which is mycelial mass for food storage and sexual reproduction. This process takes around 5 weeks and usually occurs by the fall.

Adulthood: In the fall, the sclerotia will grow from the flower ovary until it reaches full size. This will act as the fungi's source for food, warmth, shelter during the winter months, and later for reproduction during the spring. During the spring, the sclerotia will begin germinating ascocarp s (fruiting bodies of ascomycete fungi). These stalks produce ascospores, which are ejected through small pores within the ostiole. These ascospores then become the new, viable, airborne spores which will eventually grow into new fungi after contacting a viable host. Thus, repeating the cycle.

Biogeography + Evolutionary history:

Claviceps has a wide host range, with some species attacking a singular host, others having multiple within a tribe, others having over 400 different compatible host species. Common hosts include cereals, forage grasses, wild grasses, and rushes. Ergot/Claviceps have a global range, inhabiting regions of Africa, South America, Europe/Asia, North America, Australia, and India. .

The genus is believed to have derived from a common ancestor over 100 million years ago. They are most closely related to the Epichloë and Periglandula clades. Archaic Claviceps likely appeared in the warm and humid mid-latitudinal range of Gondwanaland. The relationship between the species of the genus can be found in the biosynthetic pathways for Ergot alkaloids. Older and more evolutionary distant ancestors of Claviceps will have fewer genes which code for enzymes responsible for the catalytic synthesis of complex ergot alkaloids. For example, the largest sect of the Claviceps genus often labeled "Claviceps" possesses the genes to transcribe for enzymes which can catalyze the formation of Lysergic acid amides. Another sect sect of Claviceps more distant from the previous sect labeled "Pusillae" cannot produce these amides. Instead, they produce enzymes capable of synthesizing precursor molecules for LA amide's precursors, clavines.

Ergot alkaloids:

The various species within Claviceps posses the ability to synthesize a range of secondary metabolites called Ergot Alkaloids. Ergot alkaloids are a series of nitrogen-based compounds which are modified forms of L-tryptophan.

These alkaloids are believed to be mycotoxins, and are produced in the sclerotia of the fungi to ward off herbivory by mammals.

Ergot alkaloids can be divided up into four different groups: clavines, lysergic acid, lysergic acid amide, and ergopeptines. The creation of each begins with a series of enzymatic modifications to L-tryptophan and dimethylallyl pyrophosphate (DMAPP). The result, and starting compound for all alkaloid synthesis is Chanoclavine 1, a clavine. One notable clavine is Ergoline. Once clavines are synthesized, there are several possible modification pathways which can be taken that will produce the other groups of ergot alkaloids. The first possible combination is Lysergic acid. This is done by enzymes, catalyzing the formation of a new five-membered ring which contains a nitrogen. This compound allows for the synthesis of either Lysergic acid amides or Ergopeptines. The Lysergic acid amides are generated from the substitutions of various amine groups to the oxygen or hydroxyl of the outstanding carboxylic acid group. Several notable Lysergic acid compounds are Ergine and Lysergic acid hydroxyethylamide (LSH). Ergopeptines are synthesized by attaching one of two other molecules to the carboxylic acid. Some notable ergopeptines include Ergotamine.

Ergot function and effects:

Claviceps is well known for the Ergot alkaloid mycotoxins present in their sclerotia. Claviceps produce a wide-range of alkaloids as defense mechanisms for their developing fungal bodies, and they can cause severe toxic responses in mammals. Ergot alkaloids act as vasoconstrictors, capable of reducing the vessel diameter of blood vessels. This function is caused due to the binding effects many ergot alkaloids (like ergovaline) have with the carboxyl group present on amines. They can preferentially bind and eventually shut off the amines, preventing them from working. This effects many common hormones in the body (serotonin, histamines, dopamine), which will effect neurotransmitter function and vessel elasticity. When consumed by mammals, they can cause a disease called Ergotism. In grazing mammals like cows, a particularly susceptible genus, the symptoms of ergotism include, lack of blood flow to the extremities, heat stress, excessive salivation, and the inability to stand.

In humans, there are several different presentations of ergotism. Initially, reduction of blood flow to the limbs will cause extreme pain and discomfort. From there the disease can take two different paths. One is gangrenous ergotism, in which the constricted vessels can reduce blood flow enough to the extremities to cause tissue death. Another is convulsive ergotism, in which the patient will twitch or convulse uncontrollably, likely caused by spasms in blood vessels. Other common effects include delirium among other mental effects. There are many recorded cases in history in which the consumption of the alkaloids led to mass ergotism, such as in 945AD, France. Before the understanding of the fungus and it's alkaloids, large harvests of infected grain would make their way to the general population. Widespread egotism would ensure and there would be many deaths.