Xanthoria elegans
Encyclopedia
Xanthoria elegans, commonly known as the elegant sunburst lichen, is a lichen
ized species of fungus in the genus Xanthoria, family Teloschistaceae
. Recognized by its bright orange or red pigmentation, this species grows on rocks, often near bird or rodent perches. It has a circumpolar
and alpine
distribution. It was one of the first lichens to be used for the rock-face dating method known as lichenometry
.
as Lichen elegans in 1791, and transferred to the genus Xanthoria
by Theodor Magnus Fries (son of Elias Magnus Fries
) in 1860.
The variety form X. elegans var. granulifera, characterized by having isidia-like vegetative
propagules, has been reported from Greenland
and Spitsbergen
.
, a technique of estimating the age of rock faces by measuring the diameter of the lichen thalli growing on them. After an initial period of one or two decades to establish growth (the ecesis interval), X. elegans grows at a rate of 0.5 mm per year for the first century, before slowing down somewhat.
and siliceous, occasionally overgrowing moss or litter or rock. It is often found on exposed to somewhat sheltered sites, often near bird or small mammal droppings. It has also adapted successfully to growth on man-made and natural growing surfaces from the sea-water spray zone to the boreal forest and in the grasslands of the continental interior. It can thrive in areas having less than 6 centimetres (2.4 in) annual precipitation and can survive submerged in streams for much of the growing season.
Xanthoria elegans has an extremely broad circumpolar
and alpine
distribution, and is found on all continents except Australia
. It is widespread in Antarctic
regions.
The lichen is used as a model system to study the potential to resist extreme environments of outer space
. Out of various lichens tested, it showed the ability to recover from space-stimulating situations, including exposure to 16 hours of vacuum at 10−3 Pa
and UV radiation at wavelength
s less than 160 nm
or greater than 400 nm. X. elegans has survived a 18 month exposure to solar UV radiation, cosmic rays, vacuum and varying temperatures in an experiment performed by the ESA outside of the ISS
.
compounds have been identified in X. elegans, including allacinal, physcion, teloschistin, xanthorin, and erythoglaucin, murolic acid and a glycoside
derivative of murolic acid ((18R)-18-O-β-D-apiofuranosyl-(1-2)-β-D-glucopyranoside).
s have a number of physiological functions in lichens, such as enhancing the availability of light energy for photosynthesis
, and protecting the organism from the photooxidizing action of UV light. In X. elegans, like many Xanthoria species, specimens growing in areas with intense UV radiation contain more carotenoids than those grown in more shaded areas. The biosynthesis
of carotenoids is also dependent on the season of the year, as was shown in a study of X. elegans in Antarctica. The predominant carotenoid in X. elegans, responsible for the orange-yellow color, is mutatoxanthin.
, an enzyme
that breaks down certain potential carcinogen
s, rendering them less harmful.
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
ized species of fungus in the genus Xanthoria, family Teloschistaceae
Teloschistaceae
The Teloschistaceae are a family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the phylum Ascomycota....
. Recognized by its bright orange or red pigmentation, this species grows on rocks, often near bird or rodent perches. It has a circumpolar
Circumpolar
The term circumpolar may refer to:* circumpolar navigation: to travel the world "vertically" traversing both of the poles* Antarctic region** Antarctic Circle** the Antarctic Circumpolar Current** Subantarctic** List of Antarctic and subantarctic islands...
and alpine
Alpine climate
Alpine climate is the average weather for a region above the tree line. This climate is also referred to as mountain climate or highland climate....
distribution. It was one of the first lichens to be used for the rock-face dating method known as lichenometry
Lichenometry
In archaeology, palaeontology, and geomorphology, lichenometry is a geomorphic method of geochronologic aging that uses lichen growth to determine the age of exposed rock: lichens are presumed to increase in size radially at specific rates as they grow...
.
Taxonomy
Xanthoria elegans was described by Johann Heinrich Friedrich LinkJohann Heinrich Friedrich Link
Johann Heinrich Friedrich Link was a German naturalist and botanist.Link was born at Hildesheim as a son of the minister August Heinrich Link , who taught him the love for nature through collection of 'natural objects'...
as Lichen elegans in 1791, and transferred to the genus Xanthoria
Xanthoria
Xanthoria is a genus of lichenized fungi in the family Teloschistaceae.-External links:*...
by Theodor Magnus Fries (son of Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
) in 1860.
Description
The thallus of this lichen is described as foliose, having the aspect of leaves, although the central portions of the thallus may appear nearly crustose. It is small, typically less than 5 cm (2 in) wide, with lobes less than 2 mm broad, appressed to loosely appressed. The upper surface is some shade of orange while the lower surface is white, corticate, with short, sparse hapters. The vegetative propagules called soredia and isidia are absent, although apothecia are common. It has been described as possessing swollen, orange-yellow thalli (in streams), compact orange thalli (on boulders) or dark orange-red thalli on the driest rock faces.The variety form X. elegans var. granulifera, characterized by having isidia-like vegetative
Vegetative
Vegetative describes vegetation.Vegetative may also refer to:*Vegetative reproduction, a type of asexual reproduction for plants*Persistent vegetative state, a condition of people with severe brain damage...
propagules, has been reported from Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
and Spitsbergen
Spitsbergen
Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in Norway. Constituting the western-most bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea and the Greenland Sea...
.
Growth rate
X. elegans was one of the first species used for lichenometryLichenometry
In archaeology, palaeontology, and geomorphology, lichenometry is a geomorphic method of geochronologic aging that uses lichen growth to determine the age of exposed rock: lichens are presumed to increase in size radially at specific rates as they grow...
, a technique of estimating the age of rock faces by measuring the diameter of the lichen thalli growing on them. After an initial period of one or two decades to establish growth (the ecesis interval), X. elegans grows at a rate of 0.5 mm per year for the first century, before slowing down somewhat.
Habitat and distribution
This species grows on rock, both calcareousCalcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
and siliceous, occasionally overgrowing moss or litter or rock. It is often found on exposed to somewhat sheltered sites, often near bird or small mammal droppings. It has also adapted successfully to growth on man-made and natural growing surfaces from the sea-water spray zone to the boreal forest and in the grasslands of the continental interior. It can thrive in areas having less than 6 centimetres (2.4 in) annual precipitation and can survive submerged in streams for much of the growing season.
Xanthoria elegans has an extremely broad circumpolar
Circumpolar
The term circumpolar may refer to:* circumpolar navigation: to travel the world "vertically" traversing both of the poles* Antarctic region** Antarctic Circle** the Antarctic Circumpolar Current** Subantarctic** List of Antarctic and subantarctic islands...
and alpine
Alpine climate
Alpine climate is the average weather for a region above the tree line. This climate is also referred to as mountain climate or highland climate....
distribution, and is found on all continents except Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It is widespread in Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
regions.
The lichen is used as a model system to study the potential to resist extreme environments of outer space
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
. Out of various lichens tested, it showed the ability to recover from space-stimulating situations, including exposure to 16 hours of vacuum at 10−3 Pa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
and UV radiation at wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s less than 160 nm
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
or greater than 400 nm. X. elegans has survived a 18 month exposure to solar UV radiation, cosmic rays, vacuum and varying temperatures in an experiment performed by the ESA outside of the ISS
ISS
The ISS is the International Space Station.ISS may also refer to:* I See Stars, an American electronic rock band* ISS A/S, a Danish service company* Idea Star Singer, a Malayalam music reality show by Asianet TV...
.
Bioactive compounds
Various anthraquinoneAnthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula . Several isomers are possible, each of which can be viewed as a quinone derivative...
compounds have been identified in X. elegans, including allacinal, physcion, teloschistin, xanthorin, and erythoglaucin, murolic acid and a glycoside
Glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme...
derivative of murolic acid ((18R)-18-O-β-D-apiofuranosyl-(1-2)-β-D-glucopyranoside).
Carotenoids
CarotenoidCarotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
s have a number of physiological functions in lichens, such as enhancing the availability of light energy for photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
, and protecting the organism from the photooxidizing action of UV light. In X. elegans, like many Xanthoria species, specimens growing in areas with intense UV radiation contain more carotenoids than those grown in more shaded areas. The biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
of carotenoids is also dependent on the season of the year, as was shown in a study of X. elegans in Antarctica. The predominant carotenoid in X. elegans, responsible for the orange-yellow color, is mutatoxanthin.
Medicinal properties
In a screen of lichen extracts for cancer-preventing effects, the extract of X. elegans showed significant ability to enhance the activity of quinone reductaseNADPH:quinone reductase
In enzymology, a NADPH:quinone reductase is an enzyme that catalyzes the chemical reactionThe 3 substrates of this enzyme are NADPH, H+, and quinone, whereas its two products are NADP+ and semiquinone....
, an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that breaks down certain potential carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
s, rendering them less harmful.