Diatoms ( diÃÆ'¡-tom-os "cut in half", from diÃÆ'¡ , "through" or "apart", and the root of tÃÆ' Â © mn -? , "I cut.") Is a major group of microorganisms found in oceans, waterways and soil of the world. The number of diatoms lives in trillions: they produce about 20 percent of the oxygen produced on the planet each year; taking more than 6.7 billion metric tons of silicon annually from the oceans where they live; and donate nearly half of the organic matter found in the ocean. The dead diatom shell can reach half a mile at the bottom of the ocean; and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by western transatlantic winds from the bottom of a large, dry lake that covers most Saharan Africa.
Diatoms are unicellular; they can live on their own or form colonies, taking shape like ribbons, fans, zigzags, and stars. Its size ranges from 2 to 200 micrometers. In the presence of sufficient nutrients and sunlight, live diatom groups multiply approximately every 24 hours with asexual reproduction (binary division); their life span, unless they are eaten, about six days. Diatoms have two forms: some ( diatom centric ) are symmetrical radial , whereas most diatom dianoms are close to being bilaterally i> symmetric: this form is the reason for group name diatoms . The unique feature of diatomic anatomy is that they are surrounded by a silica cell wall (hydrated silicon dioxide), called a frustule. These frustules have a structural color due to their photonic nano structure, encouraging them to be described as "gems of the ocean" and "life opal." Movements mainly occur passively as a result of water currents and wind turbulances caused by wind; However, male diatom centric gametes have flagella, allowing them to move actively. Diatoms convert light energy into chemical energy by photosynthesis, an attribute they share with plants, although diatoms and plants evolve independently. Diatoms have an urea cycle, a feature they share with animals, although used differently than in animals.
The study of diatoms is a branch of phycology. Diatoms are classified in Eukaryotic Domains, organisms with membranes that surround the cell nucleus, properties that align them with animals, and separate them from Archaea and Prokaryotes bacteria. Diatoms are a type of plankton called phytoplankton, the most common of the four types of plankton. Another classification divides plankton into eight types based on size: in this scheme, diatoms are a kind of microalgae. Some systems to classify individual diatom species exist. Fossil evidence suggests that diatoms originated during or before the early Jurassic period, which was about 150 to 200 million years ago.
Diatoms are used to monitor past and present environmental conditions, and are generally used in water quality studies. Diatomaceous earth (diatomite) is a collection of diatomous shells found in the earth's crust. They are soft sedimentary rocks that contain easily crushed silica into fine powders, and usually have a particle size of 10 to 200 m. Soil diatoms are used for a variety of purposes including for water filtration, as light abrasives, in cat feces, and as dynamic stabilizers.
Video Diatom
Structure
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Diatoms have a length of 2 to 200 micrometers. Chloroplasts are yellow-brown, the location of photosynthesis, typical of heterokont, has four membranes and contains pigments such as fucoxanthin carotenoids. Individuals are usually less flagella, but they are present in male gametes of centric diatoms and have ordinary heterokont structures, unless they have no hair characteristics (mastigonemes) in other groups.
Diatoms are often referred to as "sea gems" or "live opals" because of their photonic crystal properties. The biological function of this structural staining is unclear, but he speculates that it may be related to communication, camouflage, heat exchange and/or UV protection.
Diatoms build hard but porous cell walls (called frustules or tests) that are mainly made up of silica. These silica-containing walls can be highly patterned with various pores, ribs, minute spines, ridges and altitudes; all of which can be used to describe genera and species.
The cell itself consists of two parts, each containing a basically a flat plate, or a valve and a marginal link, or a corset tape. One-half, hypotheca, slightly smaller than the other half, epitheca. Diatom morphology varies. Although the cell shape is usually circular, some cells may be triangular, square, or elliptical. The distinguishing feature of them is a hard or frustule mineral shell composed of opal (hydrated, polymerized silicic acid).
Maps Diatom
Behavior
Most diatoms can not be turned off, because their relatively dense cell walls make them easily drown. Planktonic forms in open water usually rely on the turbulent blending of the upper seafloor by the wind to keep them suspended on the surface of the sunlit water. The only mechanism for regulating buoyancy is the ionic pump.
Cells are solitary or united in various types of colonies, which may be connected by silica-containing structures; bearing mucus, rod or tube; amorphous mucilage mass; or with a chitin thread, (polysaccharides) secreted through a flattened cell process.
Biochemistry
Energy source
Diatoms are mainly photosynthetic; However some heterotrophs are obligate and can live without light provided suitable organic carbon sources are available.
Silica Metabolism
The diatom cells are contained within a unique silica cell wall known as a frustule consisting of two valves called thecae, which usually overlap one another. The biogenic silica that constitutes the cell wall is synthesized intracellularly by the polymerization of silicic acid monomers. The material is then extruded out of the cell and added to the wall. In most species, when diatoms divide to produce two daughter cells, each cell stores one of two parts and grows a smaller half in it. As a result, after each division cycle, the average size of diatom cells in the population is getting smaller. Once the cells reach a certain minimum size, not just divide, they flip.
The exact mechanism for transferring the silica absorbed by diatoms into the cell wall is unknown. Most of the diatom gene sequencing comes from the search for silica-absorption and deposition mechanisms in the nanoscale pattern in the frustule. The greatest success in this field comes from two species, Thalassiosira pseudonana , which has become a model species, since the whole genome is sequenced and methods for genetic control are established, and Cylindrotheca fusiformis , where the important silica deposition protein of silaffin was first discovered. Silaffins, a set of polycationic peptides, are found in the cell walls of C. fusiformis and can produce intricate silica structures. This structure shows the pore size that is typical for diatom patterns. When T. pseudonana underwent genome analysis it was found that it encodes the urea cycle, including a higher amount of polyamines than most genomes, as well as three different silica transport genes. In a phylogenetic study on the silica transport genes of 8 diatomic diverse groups, the transportation of silica was found to be generally clustered with species. The study also found a structural difference between the silica carrier of the pennate (bilateral symmetry) and the centric diaphome (radial symmetry). The comparative sequences in this study were used to create diverse backgrounds to identify residues that differentiate functions in the silica precipitation process. In addition, the same study found that a number of areas are preserved in species, possibly the basic structure of silica transport.
This silica transport protein is unique to diatoms, without homologues found in other species, such as sponges or rice. The differences in the silica transport genes also show the structure of proteins that evolved from two repeating units consisting of five segments bound to the membrane, indicating gene duplication or dimerization. The precipitated silica occurring from the membrane bound to the vesicles in diatoms has been hypothesized as a result of the activity of silaffin and long chain polyamines. Silica Deposition Vesicle (SDV) is characterized as an acid compartment that integrates with Golgi vesicles. Both structures of this protein have been shown to make in-vivo patterned silica sheets with irregular pores on the scale of diatom frustules. One hypothesis of how these proteins work to create complex structures is the residue conserved in SDV, which is unfortunately difficult to identify or observe due to the limited number of available diverse sequences. Although the precise mechanism of very uniform silica deposition is not yet known, the palludin-associated Thalassiosira pseudonana genes are being seen as targets for genetic control of nanoscale silica precipitation.
This decrease by forming an auxospore. It expands in size to bring up a much larger cell, which then returns to the diminished division. Auxospore production is almost always associated with meiosis and sexual reproduction.
The urea cycle
The diatom feature is the urea cycle, which links them evolutionarily with animals. This was found in a study conducted by Andrew Allen, Chris Bowler and colleagues. Their findings, published in 2011, that diatoms have a highly significant urea cycle function, because before this, the urea cycle was thought to have originated with metazoans that appeared several hundred million years after diatoms. Their study shows that while diatoms and animals use the urea cycle for different purposes, they appear to be evolutionarily related in such a way that animals and plants do not.
Pigments
The main pigments of diatoms are chlorophyll a and c, beta-carotene, fucoxanthin, diatoxanthin and diadinoxanthin.
Storage products
Storage products are chrysolaminarin and lipids.
Life cycle
Reproduction and cell size
Reproduction among these organisms is asexual by binary division, where diatoms are divided into two parts, producing two "new" diatoms with identical genes. Each new organism receives one of the two frustules - one larger, the other smaller - is owned by the parent, now called epitheca; and used to build the second smaller frustule, hypotheca. Diatoms that accept a larger frustule become the same size as the parent, but diatoms that accept smaller frustules remain smaller than their parent. This causes the average cell size of this diatom population to decline. It has been observed, however, that certain taxa have the ability to divide without causing a decrease in cell size. Nevertheless, to restore cell size to diatom populations for those who experience size reduction, sexual reproduction and additional formation should occur.
Cell division
The diploid diatom vegetable cell (2N) and thus meiosis can occur, resulting in male and female gametes which then combine to form a zygote. Zygote emits theca silica and grows into a large ball that is covered by an organic membrane, auxospore. New diatom cells with maximum size, initial cells, formed in the auxospore thus starting a new generation. Resting spores can also form in response to unfavorable environmental conditions with germination occurring when conditions improve.
Sperm motility
Diatoms are mostly non-motile; However, sperm found in some species may have flagellates, although motility is usually limited to sliding motion. In centric diatoms, small male gametes have one flagella while the female gametes are large and non-motile (oogamous). In contrast, in the starting diatoms, gametes do not have flagella (isoogamous). Specific araphid species, ie, diatoms without acne without raphe, have been documented as anisogamous and, therefore, are considered to represent the transition stage between diatoms of diatoms centric and raphid, diatoms with raphe.
Degradation by microbes
Certain species of bacteria in the oceans and lakes can accelerate the dissolution rate of silica on dead and living diatoms by using hydrolytic enzymes to break down organic algal materials.
Classification
Structure
Diatoms are divided into two groups differentiated by the frustule form: diatom centric and diatom pennate .
Diatom purnasi is bilateral symmetrical. Each of their valves has gap-shaped openings along the raphes and their shells usually extend parallel to these raphes. They produce cell movement through the cytoplasm that flows along the raphes, always moving along the solid surface.
Centric diatoms have radial symmetry. They are composed of upper and lower valves - epitheca and hypotheca - each of which consists of a valve and a corset tape that can easily slide under each other and expand to increase the content cells above the development of diatoms. The centric diaphragm cytoplasm lies along the inner surface of the shell and provides a hollow layer around a large vacuole located in the center of the cell. This large central vacuole is filled by a liquid known as a "gum cell" similar to sea water but varies with specific ion content. The cytoplasmic layer is home to some organelles, such as chloroplasts and mitochondria. Before centric diatoms begin to develop, the nucleus is at the center of one of the valves and begins moving toward the center of the cytoplasmic cage before the cleavage is complete. Centric diatoms have various shapes and sizes, depending on which axis the shell is elongated, and if there is a thorn.
Linnaean
Relationships with other organisms
Diatoms belong to large groups called heterokonts, which include autotrophs such as gold algae and seaweed; and heterotrophs such as water molds. The classification of heterokonts remains unresolved: they can be defined as divisions, phyla, empire, or something of a medium nature. As a result, diatoms rank anywhere from the class, usually called Diatomophyceae or Bacillariophyceae , to the division, usually called Bacillariophyta , with corresponding changes in their sub-group ranks. Genera and species
More than 200 genera of living diatoms are known, with an estimated 100,000 extant species.
Classes and orders
Based on the fact that diatoms either do or do not have longitudinal grooves in the valve, called raphe , the 1990 classification by Round, Crawford & amp; Mann divides the diatoms (as Bacillarophyta) into three classes, centric (22 orders); bertnate without raphe (12 orders); and decorate with raphe (11 orders), as follows:
- Class Coscinodiscophyceae: diatom centric Spherical & amp; R.M.Crawford
- Fragilariophyceae Class: pennate diatom without raphe (arapid) F.E.Round
- Bacillariophyceae class: diatom pennate with raphe (raphid) Haeckel, 1878, emend. D.G.Mann
Cladistic
Classical alternatives to the diatom resonate clades adalah sebagai berikut:
- Bacillaryophyta
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- Coscinodiscophytina
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- Coscinodiscophyceae ('radial centric')
- Bacillariophytina
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- Mediophyceae ('polar centrics')
- Bacillariophyceae (pennate diatom)
Lainnya
Another systematic approach to classification was proposed in 1995, the Hoek, Mann and Jahns systems.
Evolution and fossil record
Origin
Heterokont chloroplasts appear to be derived from red algae, not directly from prokaryotes as occurs in plants. This shows they have a newer origin than many other algae. However, fossil evidence remains small, and only with the evolution of the diatoms themselves, heterokonts make a serious impression on the fossil record.
The earliest fossils
The oldest fossil diatoms are known to originate from early Jurassic (~ 185 Ma ago), although molecular clocks and sedimentary evidence indicate an earlier origin. It has been argued that their origin may be related to the mass extinction of the final Permian (~ 250 Ma), after which many sea gaps open. The gap between these events and the time at which the first diatomous fossils appear can indicate a period when diatoms can not be identified and their evolution is unclear. Since the emergence of silicification, diatoms have made a significant impression on the fossil record, with large deposits of fossil diatoms found as far as the early Cretaceous, and some rocks (diatomic earth, diatomite, kieselguhr) are almost entirely composed of them.
Relation to silicon cycle
Although diatoms may have existed since the Triassic, their rise time and the "takeover" of the silicon cycle occurred recently. Prior to Phanerozoic (before 544 Ma), it was believed that a weak microbial or inorganic process regulated the marine silicon cycle. Furthermore, cycles appear predominantly (and more forcefully regulated) by radiolarians and silica sponges, the first as zooplankton, the latter as a fixed filter feeder especially on the continental shelf. In the last 100, I think that the silicon cycle is under tighter control, and this comes from the ecological influence of diatoms.
However, the exact time of "takeover" remains unclear, and different authors have conflicting interpretations of the fossil record. Some evidence, such as the displacement of silica-containing sponges, suggests that this takeover begins at Cretaceous (146 Ma to 65 Ma), while radiolarian evidence indicating "takeover" does not begin until Kenozoikum (65 Ma to present).
Relationships to the meadow
The expansion of grassland biomes and radiation of grass evolution during Miocene is believed to have increased dissolved silicon flux into the oceans, and has argued that it promotes diatoms during the Kenozoic era. Recent work shows that the success of diatoms is separated from the evolution of the grass, although diatom and grassland diversity is increasing greatly from the middle Miocene.
Connection to climate
The diversity of diatoms above Cenozoic is very sensitive to global temperatures, especially for polar equator-temperature gradients. The warmer seas, especially warm polar regions, have in the past been shown to have substantially lower diatomal diversity. Future warm oceans with increased polar warming, as projected in global warming scenarios, could thus in theory result in significant diatom diversity loss, although from current knowledge it is impossible to say whether this will happen quickly or just over tens of thousands of years.
Method of investigation
Diatom fossil recordings have largely been established through the recovery of the silica-containing frustrations in marine and non-marine sediments. Although diatoms have maritime and non-marine stratigraphic records, diatom biostratigraphy, based on the evolutionary origin of evolution and the unique extinction of taxa, is well developed and widely applicable in marine systems. The long ranges of diatom species have been documented through studies of ocean cores and rock sequences exposed on land. Where diatom biozones are well established and calibrated to the time scale of geomagnetic polarity (eg, Southern Ocean, North Pacific, equatorial eastern Pacific), estimates of diatom-based age can be completed in time & lt; 100,000 years old, despite the typical age resolution to dioomi Cenozoic collection of several hundred thousand years.
Diatoms that are preserved in lake sediments are widely used for paleoenvironmental reconstruction of the Quaternary climate, especially for basin lakes that experience fluctuations in water depth and salinity.
Diversification
Cretaceous records of diatoms are limited, but recent research reveals diversification of progressive diatom types. Cretaceous-Paleogene extinction events, which in the ocean dramatically affect organisms with calcareous skeletons, seem to have a relatively small impact on the evolution of diatoms.
Turnover
Although no mass extinction of marine diatom has been observed during the Kenozoic, a relatively rapid evolutionary time in a collection of marine diatom species occurs near the Paleocene-Eocene boundary and at the Eocene-Oligocene boundary. Further turnover of the assemblage occurs at various times between the middle Miocene and the late Pliocene, in response to the progressive cooling of the polar regions and the development of a collection of endemic diatoms.
A global trend towards more complex diatom frustrations has been recorded from the Oligocene to the Quaternary. This coincides with the increasingly strong circulation of sea and deep water levels caused by the increase of the latitudinal thermal gradient at the beginning of the major Antarctic ice expansion and progressive cooling through Neogen and Quaternaries to the glaciated bipolar world. This causes the diatoms to take less silica for the formation of their frustration. Increasing ocean mixing renews silica and other nutrients needed for diatomic growth in surface water, especially in upwelling coastal and ocean areas.
Genetics
Displays order tagging
In 2002, the first insight into the properties of the phaeodactylum tricornutum gene repertoire was described using 1,000 express sequence tags (ESTs). Furthermore, the number of ESTs is extended to 12,000 and diatom EST databases are built for functional analysis. This sequence has been used to make a comparative analysis between P. tricornutum and the putative complete protein of green alga Chlamydomonas reinhardtii , red algae Cyanidioschyzon merolae , and diatoms Thalassiosira pseudonana . The diatom EST database now consists of over 200,000 ESTs of P. tricornutum (16 libraries) and T. pseudonana (7 libraries) cells grow in different conditions, many of which according to different abiotic pressures.
Genome sequencing
In 2004, the entire genome of centric diatom, Thalassiosira pseudonana (32.4 Mb) was sequenced, followed in 2008 with a batch diatom sequence, Phaeodactylum tricornutum (27.4 Mb )). Comparisons of the two revealed that the genomic trace
tricornutum included a fewer genes (10402 versus 11,776) than T. pseudonana ; there is no major synteny (gene sequence) that can be detected between the two genomes. T. pseudonana genes exhibit an average of ~ 1.52 introns per gene compared with 0.79 in P. tricornutum , indicating recent widespread intron gain diatoms centric. Despite the relatively recent evolutionary difference (90 million years), the degree of molecular differences between centris and pennates shows a rapid rate of evolution in Bacillariophyceae compared to other eukaryotic groups. Comparative genomics also determined that the specific class of the transposable, retrotransposon (or CoDis) element of Diatom Copia, has been significantly amplified in the genomic P. tricornutum associated with T. pseudonana , is 5 , 8 and 1% of each genome.
Endosymbiotic gene transfer
Diatom genomics carries a lot of information about the level and dynamics of the endosymbiotic gene transfer process (EGT). Comparisons of T. pseudonana proteins with homologues in other organisms show that hundreds have their closest homologues in the Plantae lineage. EGT against the diatom genome can be illustrated by the fact that the T. pseudonana genome encodes six proteins most closely related to the gene encoded by the nukleomorf genome Guillardia theta < cryptomonad). Four of these genes are also found in the red algal plastics genome, thereby showing successive EGT from placal red algae to red nucleus nuclei (nucleus) to the heterocontent host nuclei. Recent phylogenetic analyzes of diatom proteomats provide evidence of a prasinophyte-like endosimbion in a common ancestor of chromalveolate as supported by the fact that 70% of diatomic genes of Plantae originated from the green lineage and that the gene was also found in the genome. of other stramenopiles. Therefore, it is proposed that chromalveolates are a product of secondary secondary endosimblikosis with green algae, followed by a second algae with red algae preserving previous genomic traces but replacing green plastids. However, the phylogenic analysis of diatomic proteins and a history of chromalveolate evolution are likely to take advantage of complementary genomic data from less sorted sequelaes such as red algae.
Horizontal gene transfer
In addition to EGT, horizontal gene transfer (HGT) can occur independently of endosymbiotic events. The publication of the P. tricornutum genome reported that at least 587 P. tricornutum genes appear to be closest to the bacterial gene, accounting for more than 5% of P. tricornutum proteome. About half of these are also found in the genome's T. pseudonana, proving their ancient incorporation into diatomic bloodlines.
Ecology
Distribution
Diatoms are a widespread group and can be found in the oceans, in fresh water, on the ground, and on moist surfaces. They are one of the dominant components of phytoplankton in nutrient-rich coastal waters and during marine spring blooms, as they can split faster than other phytoplankton groups. Most live in open waters, although some live as surface films at the water sediment interface (benthic), or even in wet atmospheric conditions. They are very important in the oceans, where they contribute about 45% of the total production of oceanic organic matter. Spatial distribution of marine phytoplankton species is constrained horizontally and vertically.
Growth
Planktonic diatoms in freshwater and marine environments typically show a boom and bust lifestyle (or "blossom" and "bust"). When conditions in the top mixture (nutrients and light) are favorable (as in spring), competitive advantage and rapid growth rates allow them to dominate the phytoplankton community ("boom" or "bloom"). Thus they are often classified as opportunistic r-strategies ( ie organisms ecologically defined by high growth rates, r ).
Contribution to the modern ocean silicon cycle
Diatoms contribute in a significant way to modern silicon ocean cycles: they are the source of most biological production.
Impact
Freshwater Diatoms Didymosphenia geminata, commonly known as Didymo, causes severe environmental degradation in the water course in which it blooms, producing a large amount of jellylike material chocolate called "chocolate snot" or "snot rock". This diatom is derived from Europe and is an invasive species both in antipodes and in parts of North America. The problem is most often noted from Australia and New Zealand.
When conditions change poorly, usually after nutrient depletion, diatom cells usually increase in sink levels and out of the top mixture ("bust"). This sink is caused by loss of buoyancy control, mucus synthesis attached to diatom cells together, or heavy resting spore production . Sinking of the top mixture removes diatoms from unfavorable conditions for growth, including higher shepherding and temperature populations (which in turn increases cellular metabolism). Cells that reach deeper water or shallow seabed can rest until conditions become more profitable. In the open ocean, many submerged cells sink into the depths, but the displaced population can survive near the thermocline.
Finally, the diatomal cells in this resting population go back to the top mixture layer when vertical mixing retains them. In most circumstances, this mixing also recharges the nutrients in the top mix layer, setting the scene for the next round of diatom bloom. In the open ocean (away from the upwelling continuous area), the bloom cycle, the breasts, then back to pre-blooming conditions usually occur during the annual cycle, with diatoms only becoming prevalent during spring and early summer. In some locations, however, autumn blooms can occur, caused by the breakdown of summer stratification and nutritional entrainment while light levels are still sufficient for growth. Because the vertical mixing increases, and the light level decreases as winter approaches, these flowers are smaller and shorter in life than their spring.
In the open sea, diatom blooms (spring) usually end up due to a lack of silicon. Unlike other minerals, the requirements for silicon are unique to diatoms and are not regenerated in plankton ecosystems as efficiently as, for example, nitrogen or phosphorus nutrients. This can be seen on the map of the concentration of surface nutrients - such as the decrease of nutrients along the gradient, silicon is usually the first discharged (followed normally by nitrogen then phosphorus).
Because of this bloom-and-breast cycle, diatoms are believed to play a very disproportionate role in the export of carbon from sea-surface waters (see also biological pumps). Significantly, they also play a key role in the regulation of silicon biogeochemical cycles in the modern ocean.
Reasons for success
Diatoms are ecologically successful, and occur in almost every water-containing environment - not only oceans, seas, lakes, and rivers, but also soil and wetlands. The use of silicon by diatoms is believed by many researchers as the key to this ecological success. Raven (1983) notes that, relative to organic cell walls, the frustration of silica requires less energy to synthesize (about 8% of comparable organic walls), potentially significant savings in the overall energy budget of the cell. In the present classical study, Egge and Aksnes (1992) found that the dominance of the mesocosm community diatoms was directly related to the availability of silicic acid - when the concentrations were greater than 2 Ã,Âμmol m -3 , they found that diatoms usually represents more than 70% of the phytoplankton community. Other researchers have suggested that biogenic silica in diatom cell walls act as an effective pH buffer agent, facilitating the conversion of bicarbonate to dissolve CO 2 (which is more easily assimilated). In general, despite the possible advantages of using silicon, diatoms usually have higher growth rates than other algae of the same size.
Source for collection
Diatoms can be obtained from various sources.
Marine
Marine diatoms can be collected by direct water sampling, and benthic forms can be secured by eroding barnacles, oysters and other shells.
Fresh waters
Diatoms are often present as brown coatings, slippery on rocks and submerged sticks, and can be seen to "flow" with river currents. Surface mud ponds, trenches, or lagoons almost always produce some diatoms.
algae and plants
Diatoms of life are often found attached in large quantities to filament algae, or forming gelatinous masses in various submerged plants. Cladophora is often covered with Cocconeis , an elliptical diatom; Vaucheria is often covered with small forms.
Animal alimentary tract
Because diatoms form an important part of mollusk, tunicata, and fish food, this animal's digestive tract often produces forms that are not easily secured by other means.
Cultivation
Diatoms can be made by filling the bottle with water and mud, wrapping it in black paper and letting the sunlight fall directly to the surface of the water. In a day, diatoms will get to the top in the waste and can be isolated.
Human use
Paleontology
Decomposition and decay of diatoms cause organic and inorganic sediments (in the form of silicates), an inorganic component that can lead to methods of analyzing the past marine environment by pouring ocean floor or bay sludge, since inorganic matter is embedded in the deposition of clays and mud and forms a permanent geological record of the sea layer. (See fluid containing silica).
Industrial
Diatoms, and their shells (frustules) as diatomites or diatomaceous earth, are important industrial resources used for fine polishing and liquid filtration. The complex structure of their microscopic shells has been proposed as an ingredient for nanotechnology.
Diatoms are also used to help determine the origin of the substance they contain, including sea water.
Forensics
The main purpose of diatom analysis in forensics is to distinguish death by immersion from the body's post-mortem immersion in water. Laboratory tests can reveal the presence of diatoms in the body. Because the diatom-based silica skeletons are not easy to decompose, they can sometimes be detected even in very rotting bodies. Because they do not occur naturally in the body, if laboratory tests show diatoms in corpses from the same species found in the water where the body was found, then that might be good evidence to sink as the cause of death. The mixture of diatom species found in the corpse may be the same or different from the surrounding water, indicating whether the victim sank at the same spot where the body was found.
Nanotechnology
The precipitated silica by diatoms also proves beneficial for nanotechnology. Repeated and reliable diatoms cells produce valves of various shapes and sizes, potentially allowing diatoms to produce micro or nanoscale structures that may be used in a variety of devices, including: optical systems; semiconductor nanolithography; and even vehicles for drug delivery. With appropriate artificial selection procedures, diatoms that produce valves of certain shapes and sizes may evolve for cultivation in the chemostate culture to mass-produce nano components. It has also been suggested that diatoms can be used as components of solar cells by replacing the photosensitive titanium dioxide for silicon dioxide that diatoms typically use to make their cell walls. Diatom biofuel producing solar panels has also been proposed.
History of discovery
The first diatoms formally described in the scientific literature, colonial Bacillaria paradoxa, were discovered in 1783 by Danish naturalist Otto Friedrich MÃÆ'¼ller.
Scanning electron microscope images
References
External links
- Diatom EST database, ÃÆ' â € ° cole Normale SupÃÆ'Â © rieure
- Plankton * Net, database taxonomy including image of diatom species
- Diatoms Life and Ecology, University of California Paleontology
- Diatoms: 'Nature's Marbles', Eureka site, University of Bergen
- Biodiversity and ecology of Diatoms, Image Recovery and Microfossil Picture Circulation for Learning and Education (MIRACLE), University College London
- Diatoms Page, Royal Botanic Garden Edinburgh
- Geometry and Patterns in Nature 3: Holes in radiolarian and diatom tests
- Diatom QuickFacts, Monterey Bay Aquarium Research Institute
- The Algae Academy of Philadelphia Institute of Natural History (ANSP) database
- Diatom taxa Philadelphia Academy of Natural Sciences (ANSP)
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