Pilobolus crystallinus
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| Pilobolus crystallinus | ||||||||||||||
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| Binomial name | ||||||||||||||
| Pilobolus crystallinus var. crystallinus (F.H. Wigg.)Tode(1784) |
Description and significance
The species Pilobolus crystallinus is a type of spore forming fungus that falls into the order of a mucor. According to Wikipedia two other common names for this fungus are the “Dung Cannon” or the “Hat Thrower”. This fungus begins its life cycle in the form of a sporangium that has been discharged onto some grass. Herbivorous animals which are animals that eat grass such as cows, horses, deer’s, etc. comes along and eat the grass with the sporangium sitting on it. The sporangium passes through the digestive tract of the animal without causing any harm to the animal and without germinating. It is excreted outside the host in the feces of the animal where it begins germination growing as mycelium. They grow 2-4 centimeters tall under surfaces where oxygen concentration is low because oxygen prevents radial growth of it hyphae. The pilobolus decays the feces of the animal using the nitrogen, water etc. found in the feces as its source of food. Once the nutrients in the feces are depleted the pilobolus shoots it sporangium away from the feces into a new set of grass where it will sit waiting again to be eaten by herbivorous animals so it can repeat the lifecycle. McVickar in 1942 and later Ootaki et al. in 1993 categorized the development of pilobolus crystallinus into six stages. In the first stage there is elongation of the sporangiophore at the apex without rotation. The second stage a sporangiophore develops into a sporangium. In the third stage no growth occurs and in the fourth stage a subsporangial vesice starts expanding under the sporangium. Stage five spore maturation occurs and the hypha region below the subsporangial vesicle elongates and in the last stage, stage six the subsporangial vesicle bursts open and the sporangium are releases into the air.
This is a time lapse video pilobolus crystallinus development which was documented by Dave Kalb and Kent Loeffler from Cornell University
Genome structure
Cell structure and metabolism
• Scanning and transmission electron microscope has been used in studying the structure of pilobolus crystallinus. The stalk which is a structure that resembles a plant stem is transparent and it rises above the feces. The stalk is always oriented towards the sunlight which increases the chances that the sporangium will land on a new set of grass once they have been dispersed. The subsporangial vesicle is a balloon like structure found at the end of the stalk. This vesicle fills with fluid and builds up a pressure called turgor pressure. Turgor pressure is the force that keeps the pilobolus upright and once the pressure builds up to 7 ATM or greater the pilobolus is able shoot its sporangium to a fresh set of grass up to 2 meters away which is 6 feet reaching speed of 0-45 mph during the first millimeter of travel. The subsporangial vesicle also serves the function as a lens focusing light towards the base of the vesicle through the carotenoid pigments. On top of the subsporangial vesicle there is one black sporangium which is the structure that produces and contains the spores. The spores within the sporangium are called sporangiospores and the sporangiospore is an asexual fruiting structure found in the pilobolus species of fungus. There are two different sizes of calcium oxalate crystals, some large and some small covering the surface of the sporangium. These crystals are hydrophobic so when the spores of the pilobolus are shot into the air the hydrophobic part is repelled by the dew on the grass causing the sporangium to flip over so that they land on their bottom which is sticky. The large crystals surround the spines with a central pore which serves as protection. The vesicle contains a mucus like substance which enables the spores that stick to grass it lands on. It travels through the digestive systems of animals and begins it growth in their feces.
Ecology
Pilobolus crystallinus is a heterotrophic organism. It produces exoenzymes to digest its food outside its body before it ingest the nutrients. It is dependent on the nitrogen source found in the dung of animals as it food source. It also needs the water found in the feces of animals in order to disperse its spores. Nematodes has a symbiotic relationship with pilobolus crystallinus in that they assist the fungi with decomposition of the animal feces but when the nutrients become depleted the nematodes sits on top of the fungi so that it gets launched towards a new food source.
Pathology
Herbivorous animals such as deer’s, cattle, elk, horses’ etc. can become infected by parasitic organisms called lungworms. The larva of the lungworm is excreted in the feces of these animals. The larva can position themselves on the sporangiophores of philobolus crystillinus and it is launched with the sporangium where they now have the ability to infect a new host.
Application to Biotechnology
Current Research
References
1)http://www.plantpath.cornell.edu/PhotoLab/TimeLapse2/Pilobolus1_credit_FC.html
2)http://en.wikipedia.org/wiki/Pilobolus_crystallinus
3)http://www.jstor.org/pss/3757932