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88-455: The dictyostelids ( Dictyostelia/Dictyostelea , ICZN , Dictyosteliomycetes , ICBN ) or cellular slime molds are a group of slime molds or social amoebae . When food (normally bacteria) is readily available dictyostelids behave as individual amoebae, which feed and divide normally. However, when the food supply is exhausted, they aggregate to form a multicellular assembly, called a pseudoplasmodium, grex , or slug (not to be confused with

176-570: A model organism . It can be observed at organismic, cellular, and molecular levels primarily because of their restricted number of cell types and behaviors, and their rapid growth. It is used to study cell differentiation, chemotaxis, and apoptosis , which are all normal cellular processes. It is also used to study other aspects of development, including cell sorting, pattern formation, phagocytosis, motility, and signal transduction. These processes and aspects of development are either absent or too difficult to view in other model organisms. D. discoideum

264-413: A "primitive farming behaviour" in D. discoideum colonies. Described as a " symbiosis " between D. discoideum and bacterial prey, about one-third of wild-collected D. discoideum colonies engaged in the " husbandry " of the bacteria when the bacteria were included within the slime mold fruiting bodies. The incorporation of the bacteria into the fruiting bodies allows the "seeding" of the food source at

352-483: A cellular aggregate and at the center of the aggregate the zygote giant cell ingests the surrounding amoebae. Phagocytosis is followed by digestion of the ingested amoebae. Next the zygote forms a macrocyst characterized by a surrounding extracellular cellulose sheath. After the macrocyst is formed it ordinarily remains dormant for a period before germination can occur. Within the macrocyst the diploid zygote undergoes meiosis followed by successive mitotic divisions. When

440-494: A crucial role for persistence and dispersal of some pathogens in the environment. Transient association with amoebae has been reported for a number of different bacteria, including Legionella pneumophila , many Mycobacterium species, Francisella tularensis , and Escherichia coli , among others. Agriculture seems to play a crucial role for pathogens' survival, as they can live and replicate inside D. discoideum , making husbandry. Nature ’s report has made an important advance in

528-419: A food-rich region. This balance of the costs and benefits of the behavior may contribute to the fact that a minority of D. discoideum colonies engage in this practice. D. discoideum is known for eating Gram-positive , as well as Gram-negative bacteria , but some of the phagocytized bacteria, including some human pathogens, are able to live in the amoebae and exit without killing the cell. When they enter

616-405: A general characteristic of the innate immune system in social amoebae. The number of sentinel cells varies depending on the farming status of wild D. discoideum . When exposed to a toxic environment created by the use of ethidium bromide, it was shown that the number of sentinel cells per millimeter was lower for farmers than non-farmers. This was concluded by observing the trails left behind as

704-597: A general lacking ability to encyst, but its spores have shown better resistances against lower temperatures relative to spores from other groups. The internal phylogeny of the Dictyostelids is shown in the cladogram . Cavenderia Acytostelium Heterostelium Rostrostelium Dictyostelium Polysphondylium Speleostelium Tieghemostelium Hagiwaraea Raperostelium Class Dictyostelia Lister 1909 em. Olive 1970 Dictyostelium shares many molecular features with macrophages ,

792-511: A group of cells, and chemical waves of varying cAMP concentration propagate through the group in spirals. An elegant set of mathematical equations that reproduces the spirals and the streaming patterns of D. discoideum was discovered by mathematical biologists Thomas Höfer and Martin Boerlijst. Mathematical biologist Cornelis J. Weijer has proven that similar equations can model its movement. The equations of these patterns are mainly influenced by

880-686: A homonymy usually produces the same problems as if there were no rules: conflicts between entirely independent and unconnected groups of taxonomists working in different animal groups. Very often the Commission must be asked to take a decision. Examples: For names above the superfamily level, the principle of homonymy does not apply. Examples: Family-rank names and genus-rank names cannot be homonyms of one another, even if identical. Example: Animal, plant, and fungi nomenclature are entirely independent from each other. The most evident shortcoming of this situation (for their use in biodiversity informatics )

968-465: A model organism. While D. discoideum can be grown in liquid culture, it is usually grown in Petri dishes containing nutrient agar and the surfaces are kept moist. The cultures grow best at 22–24 °C (room temperature). D. discoideum feed primarily on E. coli , which is adequate for all stages of the life cycle. When the food supply is diminished, the myxamoebae aggregate to form pseudoplasmodia. Soon,

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1056-586: A new myxamoeba upon dispersal. This is an example of how apoptosis is used in the formation of a reproductive organ, the mature fruiting body. A recent major contribution from Dictyostelium research has come from new techniques allowing the activity of individual genes to be visualised in living cells. This has shown that transcription occurs in "bursts" or "pulses" ( transcriptional bursting ) rather than following simple probabilistic or continuous behaviour. Bursting transcription now appears to be conserved between bacteria and humans. Another remarkable feature of

1144-557: A new site in search of food bacteria. Sentinel cells make up approximately 1% of the total number of slug cells, and the number of sentinel cells remains constant even as they are being released. This indicates a constant regeneration of sentinel cells within the slugs as they are being removed along with toxins and pathogens. Sentinel cells are present in the slug even when there are no toxins or pathogens to be removed. Sentinel cells have been located in five other species of Dictyostelia , which suggests that sentinel cells can be described as

1232-472: A phagosome the fusion with lysosomes is blocked and these unmatured phagosomes are surrounded by host cell organelles such as mitochondria, vesicles, and a multilayer membrane derived from the rough endoplasmic reticulum (RER) of amoebae. The role of the RER in the intracellular infection is not known, but the RER is not required as a source of proteins for the bacteria. The bacteria reside within these phagosomes during

1320-406: A primitive organism with no apparent sense of gravity. Apoptosis (programmed cell death) is a normal part of species development. Apoptosis is necessary for the proper spacing and sculpting of complex organs. Around 20% of cells in D. discoideum altruistically sacrifice themselves in the formation of the mature fruiting body. During the pseudoplasmodium (slug or grex) stage of its life cycle,

1408-532: A slug. The slug is about 2–4 mm long, composed of up to 100,000 cells, and is capable of movement by producing a cellulose sheath in its anterior cells through which the slug moves. Part of this sheath is left behind as a slimy trail as it moves toward attractants such as light , heat , and humidity in a forward-only direction. Cyclic AMP and a substance called differentiation-inducing factor , help to form different cell types. The slug becomes differentiated into prestalk and prespore cells that move to

1496-422: A temperature about 2 °C below the temperature to which they had been acclimated. This complicated behavior has been analyzed by computer modeling of the behavior and the periodic pattern of temperature changes in soil caused by daily changes in air temperature. The conclusion is that the behavior moves slugs a few centimeters below the soil surface up to the surface. This is an amazingly sophisticated behavior by

1584-480: A thick, cellulose wall to protect it. This is known as a macrocyst . Inside the macrocyst, the giant cell divides first through meiosis , then through mitosis to produce many haploid amoebae that will be released to feed as normal amoebae would. Homothallic D. discoideum strains AC4 and ZA3A are also able to produce macrocysts. Each of these strains, unlike heterothallic strains, likely express both mating type alleles ( matA and mata ). While sexual reproduction

1672-434: A variety of host cell factors during Legionella infections. International Code of Zoological Nomenclature Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature . This implies that animals can have the same generic names as plants (e.g. there is a genus Abronia in both animals and plants). The rules and recommendations have one fundamental aim: to provide

1760-441: Is 1–2 mm tall and is now able to start the entire cycle over again by releasing the mature spores that become myxamoebae. Although D. discoideum generally reproduces asexually , D. discoideum is still capable of sexual reproduction if certain conditions are met. D. discoideum has three different mating types and studies have identified the sex locus that specifies these three mating types. Type I strains are specified by

1848-414: Is available on-line at DictyBase . The mechanism behind the aggregation of the amoebae relies on cyclic adenosine monophosphate (cAMP) as a signal molecule. One cell, the founder of the colony, begins to secrete cAMP in response to stress. Others detect this signal, and respond in two ways: The effect of this is to relay the signal throughout the nearby population of amoebae and cause inward movement to

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1936-594: Is available. In Acytostelium , the sorocarp is supported by a stalk composed of cellulose , but in other dictyostelids the stalk is composed of cells, sometimes taking up the majority of the original amoebae. With a few exceptions, these cells die during stalk formation, and there is a definite correspondence between parts of the grex and parts of the fruiting body. Aggregation of amoebae generally takes place in converging streams. The amoebae move using filose pseudopods , and are attracted to chemicals produced by other amoebae. In Dictyostelium discoideum , aggregation

2024-608: Is closely related to higher metazoans. It carries similar genes and pathways, making it a good candidate for gene knockout . The cell differentiation process occurs when a cell becomes more specialized to develop into a multicellular organism. Changes in size, shape, metabolic activities, and responsiveness can occur as a result of adjustments in gene expression. Cell diversity and differentiation, in this species, involves decisions made from cell-cell interactions in pathways to either stalk cells or spore cells. These cell fates depend on their environment and pattern formation. Therefore,

2112-407: Is decided first by applying the code directly, and not by reference to precedent. The code is also retroactive or retrospective , which means that previous editions of the code, or previous other rules and conventions have no force any more today, and the nomenclatural acts published earlier must be evaluated only under the present edition of the code. In cases of disputes a case can be brought to

2200-399: Is important for an understanding of human inflammation, arthritis, asthma, lymphocyte trafficking, and axon guidance. Phagocytosis is used in immune surveillance and antigen presentation, while cell-type determination, cell sorting, and pattern formation are basic features of embryogenesis that may be studied with these organisms. Note, however, that cAMP oscillations may not be necessary for

2288-412: Is initiated by gametogenesis that produces small, motile gametes that fuse to form a small binucleate cell . The volume of the binucleate cell then increases to produce a giant binuclear cell. As growth proceeds, the nuclei swell, and then fuse forming a true diploid zygote giant cell. As this is occurring, amoebae have been undergoing cAMP-induced chemotaxis towards the giant cell surface. This forms

2376-404: Is possible, it is very rare to see successful germination of a D. discoideum macrocyst under laboratory conditions. Nevertheless, recombination is widespread within D. discoideum natural populations, indicating that sex is likely an important aspect of their life cycle. Because many of its genes are homologous to human genes, yet its life cycle is simple, D. discoideum is commonly used as

2464-517: Is relatively short, which allows for timely viewing of all stages. The cells involved in the life cycle undergo movement, chemical signaling, and development, which are applicable to human cancer research. The simplicity of its life cycle makes D. discoideum a valuable model organism to study genetic, cellular, and biochemical processes in other organisms. In the wild, D. discoideum can be found in soil and moist leaf litter. Its primary diet consists of bacteria , such as Escherichia coli , found in

2552-418: Is secreted by the amoebae to attract neighboring cells to a central location. As they move toward the signal, they bump into each other and stick together by the use of glycoprotein adhesion molecules. The migration stage begins once the amoebae have formed a tight aggregate and the elongated mound of cells tips over to lie flat on the ground. The amoebae work together as a motile pseudoplasmodium, also known as

2640-485: Is signalled by cAMP , but others use different chemicals. In the species Dictyostelium purpureum , the grouping is by kinship, not just by proximity. Dictyostelium has been used as a model organism in molecular biology and genetics , and is studied as an example of cell communication , differentiation , and programmed cell death . It is also an interesting example of the evolution of cooperation and cheating. A large body of research data concerning D. discoideum

2728-431: Is that the same generic name can be used simultaneously for animals and plants. For this kind of homonym the expression "hemihomonym" is sometimes used. Far more than 1000 such names are known. Examples: This is the principle that each nominal taxon in the family group, genus group, or species group has—actually or potentially—a name-bearing type fixed that provides the objective standard of reference that determines what

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2816-405: Is the principle that in cases of conflicts between simultaneously published divergent acts, the first subsequent author can decide which has precedence. It supplements the principle of priority , which states that the first published name takes precedence. The principle of the first reviser deals with situations that cannot be resolved by priority. These items may be two or more different names for

2904-564: Is the principle that the correct formal scientific name for an animal taxon , the valid name , correct to use, is the oldest available name that applies to it. It is the most important principle—the fundamental guiding precept that preserves zoological nomenclature stability. It was first formulated in 1842 by a committee appointed by the British Association to consider the rules of zoological nomenclature. Hugh Edwin Strickland wrote

2992-530: Is usually the first-published name; any later name with the same spelling (a homonym ) is barred from being used. The principles of priority and first reviser apply here. For family-group names the termination (which is rank-bound) is not taken into account. Genera are homonyms only if exactly the same — a one-letter difference is enough to distinguish them. Examples: The following are not homonyms of Argus : The following names are not homonyms of each other: Some spelling variants are explicitly defined by

3080-471: The Code as being homonyms. Otherwise the one-letter difference rule applies. In species, primary homonyms are those with the same genus and same species in their original combination. The difference between a junior primary homonym and a subsequent use of a name is undefined, but it is commonly accepted that if the name referred to another species or form, gave a description, and if there is in addition no evidence

3168-804: The Dictyostelium discoideum species and differs from the other groups with its usage of cAMP as an attractant emitted during aggregation. Fossil calibrations indicate that dictyostelids class originally diverged into two major branches approximately 0.52 billion years ago. Current theories speculate that dictyostelid stalk and spore formation originally evolved as an adaption to global glacial formations. Further subdivision of dictyostelids species likely arose as most glacial formations melted. Most species in major groups 1, 2, and 3 display an encystment ability that allows individuals to survive low temperatures, but spores have shown an increased ability in resisting lower temperatures. Group 4 differs from other major groups in

3256-419: The gastropod mollusc called a slug ). The grex has a definite anterior and posterior, responds to light and temperature gradients, and has the ability to migrate. Under the correct circumstances the grex matures forming a sorocarp (fruiting body) with a stalk supporting one or more sori (balls of spores). These spores are inactive cells protected by resistant cell walls, and become new amoebae once food

3344-533: The acidic side of the pH gradient. Experiments are often done to see how manipulations of these parameters hinder, stop, or accelerate development. Variations of these parameters can alter the rate and viability of culture growth. Also, the fruiting bodies, being that this is the tallest stage of development, are very responsive to air currents and physical stimuli. It is unknown if there is a stimulus involved with spore release. Detailed analysis of protein expression in Dictyostelium has been hampered by large shifts in

3432-439: The aggregation and the multicellular development stages. The amoebae preserve their individuality and each amoeba has its own bacterium. During the culmination stage, when the spores are produced, the bacteria pass from the cell to the sorus with the help of a cytoskeletal structure that prevents host cell destruction. Some results suggest the bacteria exploit the exocytosis without killing the cell. Free-living amoebae seem to play

3520-400: The anterior and posterior ends, respectively. Once the slug has found a suitable environment, the anterior end of the slug forms the stalk of the fruiting body and the posterior end forms the spores of the fruiting body. Anterior-like cells, which have only been recently discovered, are also dispersed throughout the posterior region of the slug. These anterior-like cells form the very bottom of

3608-521: The area of highest cAMP concentration. Within an individual cell, the mechanism is as follows: Because the internal cAMP concentration inactivates the receptor for external cAMP, an individual cell shows oscillatory behaviour. This behaviour produces beautiful spirals seen in converging colonies and is reminiscent of the Belousov–Zhabotinsky reaction and two-dimensional cyclic cellular automata . The entire genome of Dictyostelium discoideum

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3696-424: The author knew that the name was previously used, it is considered as a junior homonym. Example: Typically, junior primary homonyms are permanently invalid, but some are treated as valid if the junior and senior homonyms have been in separate genera after 1899 (Art. 57.2.1, Art. 23.9). Examples: Secondary homonyms occur when taxa with the same specific name but different original genera are later classified in

3784-404: The cell, where they reside, and when they leave the cell are not known. The research is not yet conclusive but it is possible to draw a general life cycle of D. discoideum adapted for farmer clones to better understand this symbiotic process. In the picture, one can see the different stages. First, in the starvation stage, bacteria are enclosed within D. discoideum , after entry into amoebae, in

3872-513: The code may be deemed simply "unavailable" if it fails to meet certain criteria, or fall entirely out of the province of science (e.g., the "scientific name" for the Loch Ness Monster ). The rules in the code determine which available names are valid for any taxon in the family group, genus group, and species group. It has additional (but more limited) provisions on names in higher ranks . The code recognizes no case law . Any dispute

3960-417: The collective cell migration at multicellular stages. A study has found that cAMP-mediated signaling changes from propagating waves to a steady state at a multicellular stage of D. discoideum. Thermotaxis is movement along a gradient of temperature. The slugs have been shown to migrate along extremely shallow gradients of only 0.05 °C/cm, but the direction chosen is complicated; it seems to be away from

4048-441: The commission who has the right to publish a final decision. In regulating the names of animals it holds by six central principles, which were first set out (as principles) in the third edition of the code (1985): This is the principle that the scientific name of a species, and not of a taxon at any other rank, is a combination of two names; the use of a trinomen for the name of a subspecies and of uninominal names for taxa above

4136-408: The committee's report. Examples: There are over 2 million junior synonyms recorded in zoology, primarily at the species level. The principle of coordination is that within the family group, genus group and species group, a name established for a taxon at any rank in the group is simultaneously established with the same author and date for taxa based on the same name-bearing type at other ranks in

4224-437: The corresponding group. In other words, publishing a new zoological name automatically and simultaneously establishes all corresponding names in the relevant other ranks with the same type. In the species-group, publishing a species name (the binomen ) Giraffa camelopardalis Linnaeus, 1758 also establishes the subspecies name (the trinomen ) Giraffa camelopardalis camelopardalis Linnaeus, 1758 . The same applies to

4312-428: The density of the amoeba population, the rate of the production of cyclic AMP and the sensitivity of individual amoebas to cyclic AMP. The spiraling pattern is formed by amoebas at the centre of a colony who rotate as they send out waves of cyclic AMP. The use of cAMP as a chemotactic agent is not established in any other organism. In developmental biology, this is one of the comprehensible examples of chemotaxis, which

4400-433: The dish is covered with various stages of the life cycle. Checking the dish often allows for detailed observations of development. The cells can be harvested at any stage of development and grown quickly. While cultivating D. discoideum in a laboratory, it is important to take into account its behavioral responses. For example, it has an affinity toward light, higher temperatures, high humidity, low ionic concentrations, and

4488-409: The farmers, spore production and viability were similar to that of the non-farmers. Thus, it is suggested that bacteria carried by the farmers provide an additional role of protection for the farmers against potential harm due to toxins or pathogens. In older classifications, Dictyostelium was placed in the defunct polyphyletic class Acrasiomycetes . This was a class of cellular slime molds, which

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4576-402: The formation of a diploid zygote. Heterothallic mating occurs when two amoebae of different mating types are present in a dark and wet environment, where they can fuse during aggregation to form a giant zygote cell. The giant cell then releases cAMP to attract other cells, then engulfs the other cells cannibalistically in the aggregate. The consumed cells serve to encase the whole aggregate in

4664-473: The fruiting body and the caps of the spores. After the slug settles into one spot, the posterior end spreads out with the anterior end raised in the air, forming what is called the "Mexican hat", and the culmination stage begins. The prestalk cells and prespore cells switch positions in the culmination stage to form the mature fruiting body. The anterior end of the Mexican hat forms a cellulose tube, which allows

4752-408: The gene called MatA, Type II strains have three different genes: MatB (homologous to Mat A), Mat C, and Mat D, and Type III strains have Mat S and Mat T genes (which are homologous to Mat C and Mat D). These sexes can only mate with the two different sexes and not with its own. When incubated with their bacterial food supply, heterothallic or homothallic sexual development can occur, resulting in

4840-618: The genome is clustered, leading researchers to believe it serves as centromeres. The repeats correspond to repeated sequences of amino acids and are thought to be expanded by nucleotide expansion. Expansion of trinucleotide repeats also occurs in humans, in general leading to many diseases. Learning how D. discoideum cells endure these amino acid repeats may provide insight to allow humans to tolerate them. Every genome sequenced plays an important role in identifying genes that have been gained or lost over time. Comparative genomic studies allow for comparison of eukaryotic genomes. A phylogeny based on

4928-402: The human host of Legionella . The cytoskeletal composition of D. discoideum is similar to that of mammalian cells as are the processes driven by these components, such as phagocytosis, membrane trafficking, endocytic transit and vesicle sorting. Like leukocytes, D. discoideum possess chemotactic capacity. Hence, D. discoideum represents a suitable model system to ascertain the influence of

5016-413: The knowledge of amoebic behavior, and the famous Spanish phrase translated as “you are more stupid than an amoeba” is losing the sense because amoebae are an excellent example of social behavior with an amazing coordination and sense of sacrifice for the benefit of the species. Sentinel cells in Dictyostelium discoideum are phagocytic cells responsible for removing toxic material from the slug stage of

5104-461: The location of the spore dispersal, which is particularly valuable if the new location is low in food resources. Colonies produced from the "farming" spores typically also show the same behavior when sporulating. This incorporation has a cost associated with it: Those colonies that do not consume all of the prey bacteria produce smaller spores that cannot disperse as widely. In addition, much less benefit exists for bacteria-containing spores that land in

5192-466: The macrocyst germinates it releases many haploid amoeboid cells. The Dictyostelium phylogeny tree has undergone multiple changes in the past decades. The first dictyostelid to be described was Dictyostelium mucoroides in 1869 by Osker Brefeld, and the original discovery of Dictyostelium discoideum occurred in 1935, with further discoveries from Kenneth Raper , followed by global efforts led by James Cavender and collaborators. Dictyostelium discoideum

5280-462: The maximum universality and continuity in the naming of all animals, except where taxonomic judgment dictates otherwise. The code is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa . In other words, while species concepts (and thus the definition of species) are arbitrary to some degree, the rules for names are not. The code applies only to names. A new animal name published without adherence to

5368-434: The more posterior cells to move up the outside of the tube to the top, and the prestalk cells move down. This rearrangement forms the stalk of the fruiting body made up of the cells from the anterior end of the slug, and the cells from the posterior end of the slug are on the top and now form the spores of the fruiting body. At the end of this 8– to 10-hour process, the mature fruiting body is fully formed. This fruiting body

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5456-444: The myxamoebae divide by mitosis as they feed on bacteria. The bacteria secrete folic acid , which attracts the myxamoebae. When the supply of bacteria is depleted, the myxamoebae enter the aggregation stage. During aggregation, starvation initiates the production of protein compounds such as glycoproteins and adenylyl cyclase . The glycoproteins allow for cell-cell adhesion , and adenylyl cyclase creates cyclic AMP . Cyclic AMP

5544-538: The name applies to. Dictyostelium discoideum Dictyostelium discoideum is a species of soil-dwelling amoeba belonging to the phylum Amoebozoa , infraphylum Mycetozoa . Commonly referred to as slime mold , D. discoideum is a eukaryote that transitions from a collection of unicellular amoebae into a multicellular slug and then into a fruiting body within its lifetime. Its unique asexual life cycle consists of four stages: vegetative, aggregation, migration, and culmination. The life cycle of D. discoideum

5632-426: The name of a subspecies; this establishes the corresponding species name. In the genus-group, similarly, publishing the name of a genus also establishes the corresponding name of a subgenus (or vice versa): genus Giraffa Linnaeus, 1758 and subgenus Giraffa ( Giraffa ) Linnaeus, 1758 . In the family-group, publication of the name of a family, subfamily, superfamily (or any other such rank) also establishes

5720-425: The names in all the other ranks in the family group (family Giraffidae, superfamily Giraffoidea, subfamily Giraffinae). Author citations for such names (for example a subgenus) are the same as for the name actually published (for example a genus). It is immaterial if there is an actual taxon to which the automatically established name applies; if ever such a taxon is recognised, there is a name available for it. This

5808-449: The organism has formed three main types of cells: prestalk, prespore, and anterior-like cells. During culmination, the prestalk cells secrete a cellulose coat and extend as a tube through the grex. As they differentiate, they form vacuoles and enlarge, lifting up the prespore cells. The stalk cells undergo apoptosis and die as the prespore cells are lifted high above the substrate. The prespore cells then become spore cells, each one becoming

5896-408: The organism is an excellent model for studying cell differentiation. Chemotaxis is defined as a passage of an organism toward or away from a chemical stimulus along a chemical concentration gradient. Certain organisms demonstrate chemotaxis when they move toward a supply of nutrients. In D. discoideum , the amoeba secretes the signal, cAMP, out of the cell, attracting other amoebae to migrate toward

5984-449: The organism is that it has sets of DNA repair enzymes found in human cells, which are lacking from many other popular metazoan model systems. Defects in DNA repair lead to devastating human cancers, so the ability to study human repair proteins in a simple tractable model will prove invaluable. This organism's ability to be easily isolated and cultivated in the laboratory adds to its appeal as

6072-524: The plant–animal split. Subclass Dictyosteliidae, order Dictyosteliales is a monophyletic assemblage within the Mycetozoa, a group that includes the protostelid, dictyostelid, and myxogastrid slime molds. Elongation factor-1α (EF-1α) data analyses support Mycetozoa as a monophyletic group, though rRNA trees place it as a polyphyletic group. Further, these data support the idea that the dictyostelid and myxogastrid are more closely related to each other than they are

6160-462: The protein expression profile between different developmental stages and a general lack of commercially available antibodies for Dictyostelium antigens. In 2013, a group at the Beatson West of Scotland Cancer Centre reported an antibody-free protein visualization standard for immunoblotting based on detection of MCCC1 using streptavidin conjugates. The bacterial genus Legionella includes

6248-421: The protostelids. EF-1α analysis also placed the Mycetozoa as the immediate outgroup for the animal-fungal clade. Latest phylogenetic data place dictyostelids firmly within supergroup Amoebozoa , along with myxomycetes . Meanwhile, protostelids have turned out to be polyphyletic, their stalked fruiting bodies a convergent feature of multiple unrelated lineages. The D. discoideum genome sequencing project

6336-412: The rare cases where a single zoological species can have two entirely different names at the same time, depending upon whose classification is followed. Example: Article 59.3 states that junior secondary homonyms replaced before 1961 by substitute names are permanently invalid unless the substitute name is itself not in use. Example: Double homonymy (genus and species) may or may not be homonymy in

6424-401: The same genus (Art. 57.3, 59). A secondary homonym may only be a temporary state, as it only applies so long as two species are congeneric. Under a different classification, the two species may no longer be in the same genus, and the junior name can potentially be used again (Art. 59.1), as long as it was not replaced before 1961, in which case it is permanently invalid (Art. 59.3). This is one of

6512-453: The same genus-group or species-group name was published in the same year by the same author. In these cases it is useful to cite the page where the name was established. There are cases where two homonyms were established by the same author in the same year on the same page: Homonyms occur relatively rarely in families (only if generic names are identical or very similar and adding an ending "-idae" produces identical results). Discovering such

6600-456: The same species, the snowy owl . The two names are subjective synonyms. Lönnberg 1931 acted as first reviser, cited both names and selected Strix scandiaca to have precedence. This is the principle that the name of each taxon must be unique. Consequently, a name that is a junior homonym of another name must not be used as a valid name. It means that any one animal name, in one particular spelling, may be used only once (within its group). This

6688-518: The same taxon, two or more names with the same spelling used for different taxa, two or more different spellings of a particular name, etc. In such cases, the first subsequent author who deals with the matter and chooses and publishes the decision in the required manner is the first reviser, and is to be followed. Example: Linnaeus 1758 established Strix scandiaca and Strix noctua (Aves), for which he gave different descriptions and referred to different types, but both taxa later turned out to refer to

6776-451: The slugs migrated and counting the number of sentinel cells present in a millimeter. However, the number of sentinel cells does not affect the spore production and viability in farmers. Farmers exposed to a toxic environment produce the same number of spores as farmers in a non-toxic environment, and the spore viability was the same between the farmers and non-farmers. When Clade 2 Burkholderia , or farmer-associated bacteria, are removed from

6864-414: The social cycle. Generally round in shape, these cells are present within the slug sheath where they are found to be circulating freely. The detoxification process occurs when these cells engulf toxins and pathogens within the slug through phagocytosis . Then, the cells clump into groups of five to ten cells, which then attach to the inner sheath of the slug. The sheath is sloughed off as the slug migrates to

6952-401: The soil and decaying organic matter. Uninucleate amoebae of D. discoideum consume bacteria found in their natural habitat, which includes deciduous forest soil and decaying leaves. The life cycle of D. discoideum begins when spores are released from a mature sorocarp (fruiting body). Myxamoebae hatch from the spores under warm and moist conditions. During their vegetative stage,

7040-466: The source. Every amoeba moves toward a central amoeba, the one dispensing the greatest amount of cAMP secretions. The secretion of the cAMP is then exhibited by all amoebae and is a call for them to begin aggregation. These chemical emissions and amoeba movement occur every six minutes. The amoebae move toward the concentration gradient for 60 seconds and stop until the next secretion is sent out. This behavior of individual cells tends to cause oscillations in

7128-452: The species group is in accord with this principle. This means that in the system of nomenclature for animals, the name of a species is composed of a combination of a generic name and a specific name ; together they make a " binomen ". No other rank can have a name composed of two names. Examples: In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes " binomial nomenclature "). This

7216-524: The species that causes legionnaire's disease in humans. D. discoideum is also a host for Legionella and is a suitable model for studying the infection process. Specifically, D. discoideum shares with mammalian host cells a similar cytoskeleton and cellular processes relevant to Legionella infection, including phagocytosis , membrane trafficking, endocytosis , vesicle sorting, and chemotaxis. A 2011 report in Nature published findings that demonstrated

7304-414: The strict sense: if the genera are homonyms but not the same genus, the same specific names can be used in both groups, because the species are subsequently placed in different genera when the generic homonymy is removed. Example: For disambiguating one genus-group name from its homonym, it is important to cite author and year. Citing the author alone is often not sufficient. Examples: In some cases,

7392-790: The third position. Tandem repeats of trinucleotides are abundant in Dictyostelium, which in humans cause Trinucleotide repeat disorders . Sexual development can occur when amoeboid cells are starved for their bacterial food supply and dark humid conditions are present. Both heterothallic and homothallic strains of Dictostelium can undergo mating. Heterothallic sexual development has been most extensively studied in D. discoideum , and homothallic sexual development has been most well studied in D. mucoroides . Heterothallic matings are initiated by fusion of haploid cells (gametes) from two strains of opposite mating type. This contrasts with homothallic strains that appear to express both mating types. Mating

7480-418: Was characterized by the aggregation of individual amoebae into a multicellular fruiting body, making it an important factor that related the acrasids to the dictyostelids. More recent genomic studies have shown that Dictyostelium has maintained more of its ancestral genome diversity than plants and animals, although proteome-based phylogeny confirms that amoebozoa diverged from the animal–fungal lineage after

7568-507: Was completed and published in 2005 by an international collaboration of institutes. This was the first free-living protozoan genome to be fully sequenced. D. discoideum consists of a 34-Mb haploid genome with a base composition of 77% [A+T] and contains six chromosomes that encode around 12,500 proteins. Sequencing of the D. discoideum genome provides a more intricate study of its cellular and developmental biology. Tandem repeats of trinucleotides are very abundant in this genome; one class of

7656-552: Was initially classified under ‘lower fungi,’ but the classification has since shifted the classification to under the Amoebozoa phylum where it is currently. The groupings within the dictyostelid phylogeny tree has undergone frequent reordering due to availability new evidence. Most currently accepted phylogenies of dictyostelids utilize genome sequencing and small subunit ribosomal DNA (ssu-rDNA). The dictyostelids can be further subdivided into four groups. In particular, group 4 contains

7744-417: Was published in Nature in 2005 by geneticist Ludwig Eichinger and coworkers. The haploid genome contains approximately 12,500 genes on 6 chromosomes. For comparison, the diploid human genome has 20,000-25,000 genes (represented twice) on 23 chromosome pairs. There is a high level of the nucleotides adenosine and thymidine (~77%) leading to a codon usage that favors more adenosines and thymidines in

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