FACTOID # 5: Minnesota and Connecticut are both in the top 5 in saving money and total tax burden per capita.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Dictyostelid" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Dictyostelid
Dictyostelids
Scientific classification
Domain: Eukaryota
Phylum: Amoebozoa
Class: Mycetozoa
Order: Dictyosteliida
Families & Genera

Dictyosteliidae
    Dictyostelium
    Polysphondylium
    Coenonia
Actyosteliidae
    Acytostelium Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Subgroups Mycetozoa(slime moulds) Archamoebae    Pelobiontida    Entamoebida Gymnamoebia Various others The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means of internal cytoplasmic flow. ... Typical orders Protostelia    Protosteliida Myxogastria    Liceida    Echinosteliida    Trichiida    Stemonitida    Physarida Dictyostelia    Dictyosteliida Slime moulds (or slime molds), are protists that normally take the form of amoebae, but under certain conditions, such as those harmful to the organisms, change into globular sluglike beings, for mobility, which then develop fruiting bodies that...

The dictyostelids are a group of cellular slime moulds. When food (normally bacteria) is readily available they take the form of individual amoebae, which feed and divide normally. However, when the food supply is exhausted, they aggregate to form a multicellular assembly, called a pseudoplasmodium or slug (not to be confused with the gastropod mollusc called a slug). The slug has a definite anterior and posterior, responds to light and temperature gradients, and has the ability to migrate. Under the correct circumstances the slug matures forming a fruiting body with a stalk supporting one or more balls of spores. These spores are inactive cells protected by resistant cell walls, and become new amoebae once food is available. Typical orders Protostelia    Protosteliida Myxogastria    Liceida    Echinosteliida    Trichiida    Stemonitida    Physarida Dictyostelia    Dictyosteliida Slime moulds (or slime molds), are protists that normally take the form of amoebae, but under certain conditions, such as those harmful to the organisms, change into globular sluglike beings, for mobility, which then develop fruiting bodies that... Alternate meanings: Amoeboid, Amoebozoa For other uses, see Amoeba (disambiguation). ... Subclasses Eogastropoda (True Limpets and relatives) Orthogastropoda The gastropods, gasteropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 known living species comprising the snails and slugs as well as a vast number of marine and freshwater species. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia † Helcionelloida † ?Bellerophontidae The molluscs (British spelling) or mollusks (American spelling) are members of the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood. ... Subinfraorders, superfamilies, and families See text Slugs are gastropod mollusks without shells or with very small internal shells, in contrast to snails, which have a prominent coiled shell. ...


In Acytostelium, the fruiting body 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 slug 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, aggregation is signalled by cAMP, but others use different chemicals. In the species Dictyostelium purpureum, the grouping is by kinship, not just by proximity. Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ... Structure of cAMP Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3-5-cyclic adenosine monophosphate) is a molecule that is important in many biological processes; it is derived from adenosine triphosphate (ATP). ...


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 (see e.g. Strassman et al., 2000, Dao et al., 2000, Brännström & Dieckmann 2005). A large body of research data concerning D.discoideum is available on-line at DictyBase. A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ... Molecular biology is the study of biology at a molecular level. ... Molecular genetics is the field of biology which studies the structure and function of genes at a molecular level. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Embryonic stem cells differentiate into cells in various body organs. ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... dictyBase is an online bioinformatics database for the model organism Dictyostelium discoideum. ...


Life cycle of Dictyostelium Image File history File links This is a lossless scalable vector image. ...

Contents

Mechanism of aggregation in Dictyostelium

Diagram showing how a Dictyostelium discoideum amoeba responds to cAMP
Diagram showing how a Dictyostelium discoideum amoeba responds to cAMP

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: Image File history File links A diagram showing how the slime mold, Dictyostelium discoideum, relays and responds to a cAMP stimulus. ... Image File history File links A diagram showing how the slime mold, Dictyostelium discoideum, relays and responds to a cAMP stimulus. ... Structure of cAMP cAMP represented in three ways, the left with sticks-representation, the middle with structure formula, and the right with space filled representation. ...

  • The amoeba moves towards the signal.
  • The amoeba secretes more cAMP to boost the signal.

The effect of this is to relay the signal throughout the nearby population of amoebae and cause inward movement to the area of highest cAMP concentration.


Within an individual cell, the mechanism is as follows:

  1. cAMP reception at the cell membrane activates a G-protein
  2. G protein stimulates Adenylate cyclase
  3. cAMP diffuses out of cell into medium
  4. Internal cAMP inactivates the external cAMP receptor.
  5. A different g-protein stimulates Phospholipase C
  6. IP3 induces calcium ion release
  7. Calcium ions act on the cytoskeleton to induce the extension of pseudopodia.

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 cyclic cellular automata. G-proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. ... Epinephrine binds its receptor, that associates with an heterotrimeric G protein. ... A phospholipase is an enzyme that converts phospholipids into fatty acids and other lipophilic substances. ... IP3 can refer to the following: Inositol triphosphate (biochemistry) Third-order_intercept_point (radiocommunication) This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... The eukaryotic cytoskeleton. ... Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ... Oscillation is the variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... A Belousov-Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that result in the establishment of a nonlinear chemical oscillator. ... A one-dimensional cyclic cellular automaton with n = 4, run for 300 steps from a random initial configuration. ...


Genome

The entire genome of Dictyostelium discoideum was published in Nature in 2005 by geneticist Ludwig Eichinger and coworkers. It contains approximately 12,500 genes on 6 chromosomes. For comparison, the human genome has 20,000-25,000 genes on 46 chromosomes. There is a high level of the nucleotides adenosine and thymidine (~77%) leading to a codon usage that favors more adenosines and thymidines in the third position. Tandem repeats of trinucleotides are abundant in Dictyostelium, which in humans cause Trinucleotide repeat disorders. “Natural” redirects here. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... A graphical representation of the normal human karyotype. ... Adenosine is a nucleoside comprised of adenine attached to a ribose (ribofuranose) moiety via a β-N9-glycosidic bond. ... The chemical structure of deoxythymidine Thymidine (more precisely called deoxythymidine can also be labelled deoxyribosylthymine, and thymine deoxyriboside) is a chemical compound, more precisely a pyrimidine deoxynucleoside. ... Trinucleotide repeat disorders (also known as trinucleotide repeat expansion disorders, expansion disorders or codon reiteration disorders) are due to stretches of DNA in a gene that contain the same trinucleotide sequence repeated many times. ...


Classification

First discovered in a North Carolina forest in 1935, Dictyostelium was at first classified under 'lower fungi.' and in subsequent years into the kingdoms Proctoctista, Fungi and Tubulomitochondrae. By the 90s most scientists accepted the current classification.
The genome of Dictyostelids is more similar to those of animals and plants than those of fungi, and many of the genes regulating development of the foetus are likely derived from a very similar organism.


References

1. The genome of the social amoeba Dictyostelium discoideum (2005) Nature 435, 43-57
2. Dictyostelium (2007)
3. Low Society (2004)
Strassman JE, Zhu Y, and Queller DC. (2000) Altruism and social cheating in the social amoeba Dictyostelium discoideum. Nature.


Dao DN, Kessin RH, and Ennis HL (2000). Developmental cheating and the evolutionary biology of Dictyostelium and Myxococcus. Microbiology


Brännsröm Å and Dieckmann U (2005). Evolutionary dynamics of altruism and cheating among social amoebas. Proceedings of the Royal Society of London B.


External links

  • dictyBase Online Informatics Resource for Dictyostelium
  • dictyBase wiki official wiki site for dictyBase
  • Dictyostelium discoideum Genome Project

  Results from FactBites:
 
Dictyostelid - Wikipedia, the free encyclopedia (436 words)
The dictyostelids are a group of cellular slime moulds.
In Acytostelium, the fruiting body 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 slug and parts of the fruiting body.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m