Related Research Articles
A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens have different properties from those of its component organisms. Lichens come in many colors, sizes, and forms and are sometimes plant-like, but lichens are not plants. Lichens may have tiny, leafless branches (fruticose), flat leaf-like structures (foliose), flakes that lie on the surface like peeling paint (crustose), a powder-like appearance (leprose), or other growth forms.
The pioneer species are hardy species which are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by fire. Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants. Since some uncolonized land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration. Note that they are often photosynthetic plants, as no other source of energy except light energy is often available in the early stages of succession, thus making it less likely for a pioneer species to be non-photosynthetic. The plants that are often pioneer species also tend to be wind-pollinated rather than insect-pollinated, as insects are unlikely to be present in the usually barren conditions in which pioneer species grow; however, pioneer species tend to reproduce asexually altogether, as the extreme or barren conditions present make it more favourable to reproduce asexually in order to increase reproductive success rather than invest energy into sexual reproduction. Pioneer species will die creating plant litter, and break down as "leaf mold" after some time, making new soil for secondary succession, and nutrients for small fish and aquatic plants in adjacent bodies of water.
Cladonia rangiferina, also known as reindeer lichen or grey reindeer lichen, is a light-colored, fruticose lichen belonging to the family Cladoniaceae. It grows in both hot and cold climates in well-drained, open environments. Found primarily in areas of alpine tundra, it is extremely cold-hardy.
Lichen planus (LP) is a chronic inflammatory and immune mediated disease that affects the skin, nails, hair, and mucous membranes. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale, commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.
In Arctic and Antarctic ecology, a hypolith is a photosynthetic organism, and an extremophile, that lives underneath rocks in climatically extreme deserts such as Cornwallis Island and Devon Island in the Canadian high Arctic. The community itself is the hypolithon.
In archaeology, palaeontology, and geomorphology, lichenometry is a geomorphic method of geochronologic dating that uses lichen growth to determine the age of exposed rock, based on a presumed specific rate of increase in radial size over time. Measuring the diameter of the largest lichen of a species on a rock surface can therefore be used to determine the length of time the rock has been exposed. Lichen can be preserved on old rock faces for up to 10,000 years, providing the maximum age limit of the technique, though it is most accurate when applied to surfaces that have been exposed for less than 1,000 years. Lichenometry is especially useful for dating surfaces less than 500 years old, as radiocarbon dating techniques are less accurate over this period. The lichens most commonly used for lichenometry are those of the genera Rhizocarpon and Xanthoria. The measured growth rates of R. geographicum tends to fall within the range of 0.9 - 0.3 millimeter per year, depending on several factors, including the size of the lichen patch.
Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited. In other words, it is the gradual growth of an ecosystem over a longer period of time.
Lithophiles are micro-organisms that can live within the pore interstices of sedimentary and even fractured igneous rocks to depths of several kilometers.
Xanthoria parietina is a foliose, or leafy, lichen. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on rocks or walls, and also on inland rocks, walls, or tree bark. It was chosen as a model organism for genomic sequencing by the US Department of Energy Joint Genome Institute (JGI).
A lithosere is a plant succession that begins life on a newly exposed rock surface, such as one left bare as a result of glacial retreat, tectonic uplift as in the formation of a raised beach, or volcanic eruptions. For example, the lava fields of Eldgjá in Iceland where Laki and Katla fissures erupted in the year 935 and the solidified lava has, over time, begun to form a lithosere.
Lichen nitidus is a chronic inflammatory disease of unknown cause characterized by 1–2 mm, discrete and uniform, shiny, flat-topped, pale flesh-colored or reddish-brown papules that may appear as hypopigmented against dark skin. Occasionally, minimal scaling is present or can be induced by rubbing the surface of the papules. The disease usually affects children and young adults and is painless and usually nonpruritic, although protracted itching may occur in some cases. It is sometimes referred to by dermatologists as "mini lichen planus".
Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects. It introduced nitrogen fixation and photosynthesis into the terrestrial habitats approximately 450 million years ago. It is also a bioindicator of habitat disturbances, freshwater quality, air pollution, carbon dioxide concentration, and climate change. Furthermore, its life cycle is complex and much research needs to be done to characterize it more completely. For decades, the presence of sexual reproduction was unknown. However, recent molecular evidence of recombination and the observation of sexual fusions of gametes to form zygotes suggest that sexual reproduction occurs.
Herminiimonas is a genus of bacteria in the Oxalobacteraceae family. It contains Betaproteobacteria that have been isolated from spring and mineral waters. The type species, H. fonticola, was first recovered from the borehole of bottled mineral water in eastern Portugal.
Herminiimonas glaciei is a species of ultramicrobacterium in the family Oxalobacteraceae. These small gram-negative cells have a variable number of long flagella at the ends and sides of their rod-shaped bodies. With dimensions of 0.5–0.9 by 0.3–0.4 µm, H. glaciei is roughly 10 to 50 times smaller than Escherichia coli. Discovered in 2009, the species was isolated from 120,000 years old glacial ice, 3,042 metres (1.9 mi) deep, from Greenland. It was revived after a long-term incubation—seven months of oxygen-free growth at 2 °C, followed by growth on agar plates at 5 °C for almost five months. DNA sequence analysis suggests that with a sequence similarity of 99.6%, H. glaciei is most closely related to H. saxobsidens, a species originally isolated from lichen-colonized rock. Loveland-Curtze, head of the team of scientists from Pennsylvania State University who found the species, speculates that it may offer insight into the existence of organisms in extraterrestrial habitats.
Herminiimonas fonticola is the type species of the bacterial genus Herminiimonas. It was first recovered from the borehole of bottled mineral water in Eastern Portugal.
Herminiimonas arsenicoxydans is a species of ultramicrobacteria. First reported in 2006, it was isolated from industrial sludge and is able to oxidise the toxic chemical element arsenic.
Boscastle to Widemouth is a coastal Site of Special Scientific Interest (SSSI) in Cornwall, England, noted for its biological and geological characteristics. The Dizzard dwarf oak woodland is unique and of international importance for its lichen communities, with 131 species recorded.
Crustose lichens form a crust that strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Foliose lichen is one of a variety of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse climates that can range from cold, dry mountains to wet, warm valleys. Lichens develop quite slowly with recorded growth rates of 0.01–27mm/year depending on the species. Their lifespan averages between 30 and 60 years.
Blastococcus is a Gram-positive, coccoid and aerobic genus of bacteria from the family of Geodermatophilaceae.
References
- ↑ Lang E, Swiderski J, Stackebrandt E, Schumann P, Spröer C, Sahin N (November 2007). "Herminiimonas saxobsidens sp. nov., isolated from a lichen-colonized rock". International Journal of Systematic and Evolutionary Microbiology. 57 (Pt 11): 2618–22. doi:10.1099/ijs.0.65163-0. PMID 17978229. Archived from the original on 2013-04-15.
