Cryptothecia rubrocincta
Encyclopedia
Cryptothecia rubrocincta is a species of lichen
in the Arthoniaceae
family of fungi
. The species is distributed in subtropical and tropical locations throughout the southeastern United States, as well as Central and South America, and has been collected infrequently in a few locales in Africa. The body of the lichen forms continuous, circular crust-like patches on dead wood, readily recognizable by the prominent red pigment
. The older, central region is covered with red, spherical to cylindrical granules. Moving outwards from the center, zones of color may be distinguished, the first gray-green, the second white, and finally a bright red cottony rim. The red and green colors of this unmistakable woodland lichen give the appearance of a Christmas wreath, suggestive of its common
North American name, the Christmas wreath lichen. The red pigment, called chiodectonic acid, is one of several chemicals the lichen produces to help tolerate inhospitable growing conditions.
of the genus Cryptothecia has been unclear, and historically, C. rubrocincta has been placed in several different genera
. Like all lichens, C. rubrocincta is an association of a fungus (the mycobiont) with a photosynthetic
organism (the photobiont), in this case, an algae
. Initially, it was unknown whether the mycobiont component of C. rubrocincta was an ascomycete
or a basidiomycete
. Although the vast majority of lichen mycobionts are from the Ascomycota, in 1937 German lichenogist Friedrich Tobler believed the mycobiont to be a basidiomycete, because he interpreted some unusual microscopic structures to be clamp connection
s, structures associated only with the basidiomycete fungi. In another publication later that year, he specified the mycobiont to be a hymenomycete
, and described the monotypic
genus Herpothallion to supersede the old name Chiodecton sanguineum. Although Vernon Ahmadjian
corroborated the presence of clamp connections in the species when he studied the species' cytology
in 1967, other researchers did not find clamp connections in specimens collected from different countries. Further doubt was cast on the possibility of a basidiomycete mycobiont with the discovery of the depside
confluentic acid in 1966, concentric bodies in 1975, and woronin bodies in 1983, as all of these characteristics are restricted to Ascomycetes.
The International Code of Botanical Nomenclature states that names of fungi adopted by Fries
in Systema Mycologicum vols. 1–3 are sanctioned, that is, they are conserved against earlier homonyms and competing synonyms. This means that the name Hypochnus rubrocinctum has priority over Byssus sanguinea. The type material of H. rubrocinctum was examined by Christian Gottfried Ehrenberg
in Berlin; it has since been destroyed, probably during the Second World War. The drawing in Erhenberg's 1820 publication serves as the lectotype
. The species was transferred to the genus Cryptothecia
by Swedish lichenologist Göran Thor in 1991, on the basis of its similarity with C. striata such as the thallus with radiate ridges, granular isidia, and presence of para-depside
s (gyrophoric acid
in C. striata and confluentic acid in C. rubrocincta).
The red and green of C. rubrocincta give it a Christmas wreath look, hence its common
North American name, the Christmas wreath lichen. The specific epithet is derived from the Latin
words ruber "red" and cinctus "girdled/encircled" or "banded". The other epithet sanguineum is the neuter form of the Latin adjective sanguineus "bloody".
means to reproduce, and is not known to have any sexual structures. From the center outwards, three color zones can be differentiated in mature specimens; the first grayish-green, the second white, and finally a bright red cottony rim.
The lichen has a distinct prothallus—fibers of whitish fungal hypha
e at the edge that lack photobiont, and which project beyond the thallus onto the growing surface. The prothallus is red to whitish in the inner part, red the in outer part. The surface of the thallus does not have a well-defined cortex, an outer layer of well-packed hyphae. The medulla (a loosely arranged layer of hyphae below the cortex and photobiont zone) is whitish but the lower part is red. It has few to many calcium oxalate
crystals that are 3–8 μm diameter. The hyphae of the medulla have many such crystals on the walls, that are 1–2 μm in diameter. The algal photobiont (technically a phycobiont, as it is a green algal photosynthetic partner) is from the genus Trentepohlia. Normally, the algae is long and filamentous; when in the lichen state, it is divided into shorter filaments. The alga has a large chloroplast
that contains droplets of beta-carotene
. The lichen is heteromerous, meaning that the mycobiont and photobiont components are in well-defined layers, with the photobiont in a more or less distinct zone between the upper cortex and the medulla. Cells are single or a few cells aggregated, with dimensions of about 8–15 by 5–11 μm.
The yeast Fellomyces mexicanus, an anamorphic member of the Cuniculitremaceae
family, was discovered growing epiphytically
on the lichen in 2005.
, Mississippi
, Alabama
and Georgia
. Although the northern limit was extended to southern Delaware
, the author later revised his opinion, and the northern limit is thought to be North Carolina
. In North Carolina, it is found on Smith Island, a notable location because it represents the northern limit of the distribution of cabbage palmetto (Sabal palmetto). The presence of this 6 meter (20 ft) tree interspersed among the dominant tree species Quercus virginiana give the island a subtropical appearance—consistent with the lichen's preferred climate.
Cryptothecia rubrocincta is also widespread in tropical and subtropical areas of the West Indies and Central and South America. In South America in is found north of Chile
and Argentina
. It is rarer in Africa, having only been collected from three geographically widely separated mountain regions: São Tomé and Príncipe
, Tanzania
, and Zaire
. The lichen may be found at altitudes ranging from sea level
to 2600 metres (8,530.2 ft) (in Colombia
).
The lichen typically grows on rough bark in sheltered and shaded habitats in moist and dense subtropical forests. More rarely, it is found on rocks or on leaves. In the USA it occurs in hammocks
(hardwood forests) and swamps which have standing water, at least part of the year. It is also common in oak or oak-pine scrub vegetation. The species is often associated with Cryptothecia striata in the USA.
in the thallus. The pigment, first isolated from the species by Hesse in 1904, is called chiodectonic acid. The lichen also contains the colorless depside
compound confluentinic acid. A 2005 study employed the technique Raman spectroscopy
to determine the chemical composition of the differently colored zones. The white crystalline zone contains calcium oxalate
dihydrate, or weddellite
, a chemical substance found in other lichens and extremophile
s growing on calcium-rich surfaces. Some have suggested that the calcium oxalate serves in the organism's survival strategy: the storage of water as a crystalline hydrate is essential for periods of drought in desiccated environments, and calcium oxalate has been identified as dissuading herbivores. Because the lichen grows on calcium-poor surfaces, calcium ions are thought to be acquired from rain, bird droppings, and airborne particles.
The chemicals in the red-colored zone include an aromatic quinone
, beta-carotene
, and chlorophyll
. The quinone is deep-red colored pigment chiodectonic acid, thought to function as a radiation protectant; in combination with beta-carotene, which has an established role in cellular DNA repair
following exposure of the organism to UV
-damage, such radiation protectants are often found in lichens and in extremophilic situations and are essential for survival.
The lighter-colored pink zone, located on the inside of the red zone, contains a mixture of chiodectonic acid, beta-carotene and calcium oxalate dihydrate, the red and white mixture of the chiodectonic acid and the calcium oxalate giving rise to the characteristically lighter color.
The elliptical brown-colored flecks, which can be observed in both the red and pink zones of the thallus, are made of confluentic acid and calcium oxalate monohydrate. The monohydrate is thought to be a more chemically stable metabolic byproduct of calcium oxalate dihydrate; the function of confluentic acid in the brown flecks is unclear.
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...
in the Arthoniaceae
Arthoniaceae
The Arthoniaceae are a family of lichenized fungi in the order Pezizales. Species have a widespread distribution, but are especially prevalent in tropical areas. Collectively, the family has a highly variable ecology, some species lichenized with green algae, and others lichenicolous—growing on...
family of fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
. The species is distributed in subtropical and tropical locations throughout the southeastern United States, as well as Central and South America, and has been collected infrequently in a few locales in Africa. The body of the lichen forms continuous, circular crust-like patches on dead wood, readily recognizable by the prominent red pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
. The older, central region is covered with red, spherical to cylindrical granules. Moving outwards from the center, zones of color may be distinguished, the first gray-green, the second white, and finally a bright red cottony rim. The red and green colors of this unmistakable woodland lichen give the appearance of a Christmas wreath, suggestive of its common
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
North American name, the Christmas wreath lichen. The red pigment, called chiodectonic acid, is one of several chemicals the lichen produces to help tolerate inhospitable growing conditions.
Taxonomy and naming
The classificationBiological classification
Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....
of the genus Cryptothecia has been unclear, and historically, C. rubrocincta has been placed in several different genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
. Like all lichens, C. rubrocincta is an association of a fungus (the mycobiont) with a photosynthetic
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...
organism (the photobiont), in this case, an algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
. Initially, it was unknown whether the mycobiont component of C. rubrocincta was an ascomycete
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
or a basidiomycete
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
. Although the vast majority of lichen mycobionts are from the Ascomycota, in 1937 German lichenogist Friedrich Tobler believed the mycobiont to be a basidiomycete, because he interpreted some unusual microscopic structures to be clamp connection
Clamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...
s, structures associated only with the basidiomycete fungi. In another publication later that year, he specified the mycobiont to be a hymenomycete
Hymenomycete
Hymenomycetes are the largest class of fungi within the phylum Basidiomycota. Many familiar fungi belong to this class, including bracket fungi and toadstools...
, and described the monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus Herpothallion to supersede the old name Chiodecton sanguineum. Although Vernon Ahmadjian
Vernon Ahmadjian
Dr. Vernon Ahmadjian is a professor emeritus at Clark University, Worcester, Massachusetts, USA. He is a specialist on lichen symbiosis and has written several books and numerous publications on this subject....
corroborated the presence of clamp connections in the species when he studied the species' cytology
Cell biology
Cell biology is a scientific discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level...
in 1967, other researchers did not find clamp connections in specimens collected from different countries. Further doubt was cast on the possibility of a basidiomycete mycobiont with the discovery of the depside
Depside
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae. Depsides have...
confluentic acid in 1966, concentric bodies in 1975, and woronin bodies in 1983, as all of these characteristics are restricted to Ascomycetes.
The International Code of Botanical Nomenclature states that names of fungi adopted by Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
in Systema Mycologicum vols. 1–3 are sanctioned, that is, they are conserved against earlier homonyms and competing synonyms. This means that the name Hypochnus rubrocinctum has priority over Byssus sanguinea. The type material of H. rubrocinctum was examined by Christian Gottfried Ehrenberg
Christian Gottfried Ehrenberg
Christian Gottfried Ehrenberg , German naturalist, zoologist, comparative anatomist, geologist, and microscopist, was one of the most famous and productive scientists of his time.- Early collections :...
in Berlin; it has since been destroyed, probably during the Second World War. The drawing in Erhenberg's 1820 publication serves as the lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
. The species was transferred to the genus Cryptothecia
Cryptothecia
Cryptothecia is a genus of crustose lichen in the Arthoniaceae family. The genus, thought to contain 75 species, has a widespread distribution, but is especially prevalent in tropical regions, with only two species being recognized in North America...
by Swedish lichenologist Göran Thor in 1991, on the basis of its similarity with C. striata such as the thallus with radiate ridges, granular isidia, and presence of para-depside
Depside
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae. Depsides have...
s (gyrophoric acid
Gyrophoric acid
Gyrophoric acid is a depside that can be found in the lichen Cryptothecia rubrocincta and in Xanthoparmelia pokomyi....
in C. striata and confluentic acid in C. rubrocincta).
The red and green of C. rubrocincta give it a Christmas wreath look, hence its common
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
North American name, the Christmas wreath lichen. The specific epithet is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
words ruber "red" and cinctus "girdled/encircled" or "banded". The other epithet sanguineum is the neuter form of the Latin adjective sanguineus "bloody".
Description
Cryptothecia rubrocincta is a crustose lichen, because it grows in the form of a surface crust. The thallus, or body of the lichen is spread out flat and can be either tightly to loosely attached to the growing surface. It is 0.15–0.30 mm thick, and can be smooth, or have low radiating ridges. The older, central region of the lichen surface has many reproductive structures called isidia; they resemble granules that are 0.1–0.4 by 0.1 mm. The species relies entirely on vegetativeVegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
means to reproduce, and is not known to have any sexual structures. From the center outwards, three color zones can be differentiated in mature specimens; the first grayish-green, the second white, and finally a bright red cottony rim.
The lichen has a distinct prothallus—fibers of whitish fungal hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
e at the edge that lack photobiont, and which project beyond the thallus onto the growing surface. The prothallus is red to whitish in the inner part, red the in outer part. The surface of the thallus does not have a well-defined cortex, an outer layer of well-packed hyphae. The medulla (a loosely arranged layer of hyphae below the cortex and photobiont zone) is whitish but the lower part is red. It has few to many calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
crystals that are 3–8 μm diameter. The hyphae of the medulla have many such crystals on the walls, that are 1–2 μm in diameter. The algal photobiont (technically a phycobiont, as it is a green algal photosynthetic partner) is from the genus Trentepohlia. Normally, the algae is long and filamentous; when in the lichen state, it is divided into shorter filaments. The alga has a large chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
that contains droplets of beta-carotene
Beta-carotene
β-Carotene is a strongly-coloured red-orange pigment abundant in plants and fruits. It is an organic compound and chemically is classified as a hydrocarbon and specifically as a terpenoid , reflecting its derivation from isoprene units...
. The lichen is heteromerous, meaning that the mycobiont and photobiont components are in well-defined layers, with the photobiont in a more or less distinct zone between the upper cortex and the medulla. Cells are single or a few cells aggregated, with dimensions of about 8–15 by 5–11 μm.
The yeast Fellomyces mexicanus, an anamorphic member of the Cuniculitremaceae
Cuniculitremaceae
The Cuniculitremaceae are a family of fungi in the order Tremellales. Cuniculitrema, the teleomorphic taxon, is known in southern Germany and Switzerland, while the anamorphic taxa have a wider distribution. The four genera of the Cuniculitremaceae family have a combined total of 25 species....
family, was discovered growing epiphytically
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
on the lichen in 2005.
Distribution and habitat
The lichen is widely distributed in the southeastern United States; in 1954 the north border of its distribution was given as a line passing through southern LouisianaLouisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
, Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
, Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
and Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
. Although the northern limit was extended to southern Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...
, the author later revised his opinion, and the northern limit is thought to be North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. In North Carolina, it is found on Smith Island, a notable location because it represents the northern limit of the distribution of cabbage palmetto (Sabal palmetto). The presence of this 6 meter (20 ft) tree interspersed among the dominant tree species Quercus virginiana give the island a subtropical appearance—consistent with the lichen's preferred climate.
Cryptothecia rubrocincta is also widespread in tropical and subtropical areas of the West Indies and Central and South America. In South America in is found north of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
and Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. It is rarer in Africa, having only been collected from three geographically widely separated mountain regions: São Tomé and Príncipe
São Tomé and Príncipe
São Tomé and Príncipe, officially the Democratic Republic of São Tomé and Príncipe, is a Portuguese-speaking island nation in the Gulf of Guinea, off the western equatorial coast of Central Africa. It consists of two islands: São Tomé and Príncipe, located about apart and about , respectively, off...
, Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
, and Zaire
Zaire
The Republic of Zaire was the name of the present Democratic Republic of the Congo between 27 October 1971 and 17 May 1997. The name of Zaire derives from the , itself an adaptation of the Kongo word nzere or nzadi, or "the river that swallows all rivers".-Self-proclaimed Father of the Nation:In...
. The lichen may be found at altitudes ranging from sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
to 2600 metres (8,530.2 ft) (in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
).
The lichen typically grows on rough bark in sheltered and shaded habitats in moist and dense subtropical forests. More rarely, it is found on rocks or on leaves. In the USA it occurs in hammocks
Hammock (ecology)
Hammocks are dense stands of hardwood trees that grow on natural rises of only a few inches higher than surrounding marshland that is otherwise too wet to support them. Hammocks are distinctive in that they are formed gradually over thousands of years rising in a wet area through the deposits of...
(hardwood forests) and swamps which have standing water, at least part of the year. It is also common in oak or oak-pine scrub vegetation. The species is often associated with Cryptothecia striata in the USA.
Chemistry
Cryptothecia rubrocincta is easily recognized by the bright red pigmentPigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
in the thallus. The pigment, first isolated from the species by Hesse in 1904, is called chiodectonic acid. The lichen also contains the colorless depside
Depside
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae. Depsides have...
compound confluentinic acid. A 2005 study employed the technique Raman spectroscopy
Raman spectroscopy
Raman spectroscopy is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system.It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range...
to determine the chemical composition of the differently colored zones. The white crystalline zone contains calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
dihydrate, or weddellite
Weddellite
Weddellite is a mineral form of calcium oxalate named for occurrences of millimeter-sized crystals found in bottom sediments of the Weddell Sea, off Antarctica...
, a chemical substance found in other lichens and extremophile
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
s growing on calcium-rich surfaces. Some have suggested that the calcium oxalate serves in the organism's survival strategy: the storage of water as a crystalline hydrate is essential for periods of drought in desiccated environments, and calcium oxalate has been identified as dissuading herbivores. Because the lichen grows on calcium-poor surfaces, calcium ions are thought to be acquired from rain, bird droppings, and airborne particles.
The chemicals in the red-colored zone include an aromatic quinone
Quinone
A quinone is a class of organic compounds that are formally "derived from aromatic compounds [such as benzene or naphthalene] by conversion of an even number of –CH= groups into –C– groups with any necessary rearrangement of double bonds," resulting in "a fully conjugated cyclic dione structure."...
, beta-carotene
Beta-carotene
β-Carotene is a strongly-coloured red-orange pigment abundant in plants and fruits. It is an organic compound and chemically is classified as a hydrocarbon and specifically as a terpenoid , reflecting its derivation from isoprene units...
, and chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
. The quinone is deep-red colored pigment chiodectonic acid, thought to function as a radiation protectant; in combination with beta-carotene, which has an established role in cellular DNA repair
DNA repair
DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and radiation can cause DNA damage, resulting in as many as 1...
following exposure of the organism to UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
-damage, such radiation protectants are often found in lichens and in extremophilic situations and are essential for survival.
The lighter-colored pink zone, located on the inside of the red zone, contains a mixture of chiodectonic acid, beta-carotene and calcium oxalate dihydrate, the red and white mixture of the chiodectonic acid and the calcium oxalate giving rise to the characteristically lighter color.
The elliptical brown-colored flecks, which can be observed in both the red and pink zones of the thallus, are made of confluentic acid and calcium oxalate monohydrate. The monohydrate is thought to be a more chemically stable metabolic byproduct of calcium oxalate dihydrate; the function of confluentic acid in the brown flecks is unclear.
External links
- Cryptothecia rubrocincta at Index FungorumIndex FungorumIndex Fungorum, an international project to index all formal names in the Fungi Kingdom. Somewhat comparable to the IPNI, but with more contributing institutions....