''Dictyostelium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of single- and multi-celled

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

phagotrophic Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is c ...

bacterivore A bacterivore is an organism which obtains energy and nutrients primarily or entirely from the consumption of bacteria. The term is most commonly used to describe free-living, heterotrophic, microscopic organisms such as nematodes as well as many sp ...

s. Though they are

Protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

a and in no way

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

, they traditionally are known as "

slime mold Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic mu ...

s". They are present in most terrestrial ecosystems as a normal and often abundant component of the soil

microflora Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found to ...

, and play an important role in the maintenance of balanced bacterial populations in soils. The genus ''Dictyostelium'' is in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Dictyosteliida, the so-called cellular slime molds or social amoebae. In turn the order is in the

infraphylum In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum. The taxonomic rank of "subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used the ...

Mycetozoa Mycetozoa is a polyphyletic grouping of slime molds. It was originally thought to be a monophyletic clade, but recently it was discovered that protostelia are a polyphyletic group within Conosa. Classification It can be divided into dictyostelid ...

. Members of the order are Protista of great theoretical interest in biology because they have aspects of both unicellularity and

multicellularity A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- ...

. The individual cells in their independent phase are common on organic

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

or in damp soils and caves. In this phase they are

amoebae An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...

. Typically, the amoebal cells grow separately and wander independently, feeding mainly on bacteria. However, they interact to form multi-cellular structures following starvation. Groups of up to about 100,000 cells signal each other by releasing chemoattractants such as

cyclic AMP Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3',5'-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transd ...

(cAMP) or glorin. They then coalesce by

chemotaxis Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemica ...

to form an aggregate that becomes surrounded by an extracellular matrix. The aggregate forms a fruiting body, with cells differentiating individually into different components of the final structure. In some species, the whole aggregate may move collectively – forming a structure known as a grex or "slug" – before finally forming a fruiting body. Basic processes of development such as differential cell sorting, pattern formation, stimulus-induced gene expression, and cell-type regulation are common to ''Dictyostelium'' and

metazoans Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...

. For further detail see family

Dictyostelid The dictyostelids (Dictyostelia/Dictyostelea, International Code of Zoological Nomenclature, ICZN, or Dictyosteliomycetes, ICBN) are a group of cellular slime molds, or social amoebae. Multicellular behavior When food (normally bacteria) is rea ...

Discovery

The cellular slime mold was formerly considered to be fungi following their discovery in 1869 by Brefeld. Although they resemble fungi in some respects, they have been included in the kingdom Protista. Individual cells resemble small amoebae in their movement and feeding, and so are referred to as myxamoebae. '' D. discoideum'' is the most studied of the genus.

Traits

Most of its life, this haploid social amoeba undergoes a vegetative cycle, preying upon bacteria in the soil, and periodically dividing mitotically. When food is scarce, either the sexual cycle or the social cycle begins. Under the social cycle, amoebae aggregate in response to

cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...

by the thousands, and form a motile slug, which moves towards light. Ultimately the slug forms a fruiting body in which about 20% of the cells die to lift the remaining cells up to a better place for sporulation and dispersal. When starved for their bacterial food supply and exposed to dark, moist conditions,

heterothallic Heterothallic species have sexes that reside in different individuals. The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of ...

or homothallic strains can undergo sexual development that results in the formation of a

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

zygote. Heterothallic mating has been best studied in '' D. discoideum'' and homothallic mating has been best studied in ''

Dictyostelium mucoroides ''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as ...

'' (strain DM7). In the heterothallic sexual cycle,

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by extending and ret ...

e aggregate in response to cAMP and sex pheromones, and two cells of opposite mating types fuse, and then begin consuming the other attracted cells. Before they are consumed, some of the prey cells form a cellulose wall around the entire group. When cannibalism is complete, the giant diploid cell is a hardy

macrocyst A macrocyst is an aggregate of cells of Dictyostelids formed during sexual reproduction enclosed in a cellulose wall. If two amoebae of different mating types are present in a dark and wet environment, they can fuse during aggregation to form ...

which eventually undergoes recombination and meiosis, and hatches hundreds of recombinants. In ''D. mucoroides'' (DM7) homothallic mating, cells are directed towards sexual development by

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

. Scientists also found the collective cell migration could occur without the presence of cAMP oscillations at multicellular stages, and novel models have been proposed to interpret this interesting phenomenon.

Social characteristics

Professor

John Tyler Bonner John Tyler Bonner (May 12, 1920 – February 7, 2019) was an American biologist who was a professor in the Ecology and evolutionary biology, Department of Ecology and Evolutionary Biology at Princeton University. He was a pioneer in the use of ce ...

(1920-2019) spent a lifetime researching the slime molds and created a number of fascinating films in the 1940s to show the life cycle; he mostly studied ''D. discoideum''. In the videos, intelligence appears to be observed as the single cells, after separation, regroup into a cellular mass. The time-lapse film captivated audiences; indeed, Bonner when giving conferences stated that the film "always stole the show". The video is available on YouTube. When the organisms congregate, the mass is made of genetically distinct cells. Through natural selection, it is determined which of the organisms' genetic information will be present in future generations. The conflict is evidenced by unequal representations of two genetically different clones in spores of a

chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of Ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...

, the reduction of functionality seen in migrating chimeras, and a differentiation inducing factor (DIF) system, akin to poison, that appears to be made of cells forcing others to cease output of genetic information.

Species

Taxonomy of ''Dictyostelium'' is complicated. It has also been confused by the different forms in the life cycle stages and by the similar ''Polysphondylium'' spp. Below are some reported examples. * ?'' Dictyostelium annularibasimum'' Li, Liu & Zhao 2016 * ?'' Dictyostelium arabicum'' Hagiwara 1991 * ?'' Dictyostelium barbarae'' Stephenson et al. 2019 * ?'' Dictyostelium culliculosum'' Li & He 2008 * ?'' Dictyostelium dichotomum'' Vadell & Cavender 2007 * ?'' Dictyostelium germanicum'' Cavender et al. 1995 * ?'' Dictyostelium globisporum'' Li & Liu 2011 * ?'' Dictyostelium insulinativitatis'' Stephenson et al. 2019 * ?'' Dictyostelium irregularis'' Olive et al. 1967 * ?''

Dictyostelium magnum ''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as ...

'' Hagiw. 1983 * ?'' Dictyostelium microsorocarpum'' Li & He 2010 * ?'' Dictyostelium roseum'' van Tieghem 1880 * ?'' Dictyostelium vermiformum'' Vadell & Cavender 2007 * '' Dictyostelium ammophilum'' Romeralo et al. 2010 ex Baldauf, Sheikh & Thulin 2017 * '' Dictyostelium aureocephalum'' Hagiwara 1991 * '' Dictyostelium aureum'' Olive 1901 * '' Dictyostelium austroandinum'' Vadell et al. 2011 * '' Dictyostelium barbibulus'' Perrigo & Romeralo 2013 * '' Dictyostelium brefeldianum'' Hagiw. 1984 * ''

Dictyostelium brevicaule ''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems as ...

'' Olive 1901 * '' Dictyostelium brunneum'' Kawabe 1982 * '' Dictyostelium capitatum'' Hagiwara 1983 * '' Dictyostelium chordatum'' Vadell et al. 2011 * '' Dictyostelium citrinum'' Vadell et al. 1995 * '' Dictyostelium clavatum'' Hagiwara 1992 * '' Dictyostelium crassicaule'' Hagiwara 1984 * '' Dictyostelium dimigraformum'' Cavender 1970 * ''

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 ...

'' Raper 1935 * '' Dictyostelium firmibasis'' Hagiwara 1971 * '' Dictyostelium gargantuum'' Vadell et al. 2011 * '' Dictyostelium giganteum'' Singh 1947 * '' Dictyostelium implicatum'' Hagiwara 1984 * '' Dictyostelium intermedium'' Cavender 1976 * '' Dictyostelium leptosomopsis'' Vadell et al. 2011 * '' Dictyostelium leptosomum'' Cavender et al. 2002 * '' Dictyostelium longosporum'' Hagiwara 1983 * '' Dictyostelium macrocephalum'' Hagiwara 1985 * '' Dictyostelium medium'' Hagiwara 1992 * ''

'' Brefeld 1869 * '' Dictyostelium pseudobrefeldianum'' Hagiwara 1996 * ''

Dictyostelium purpureum ''Dictyostelium purpureum'' is a species of ''Dictyostelium''. ''Dictyostelium purpureum'' is a distinct species from ''D. discoideum'', although it belongs in the same phenotypic grouping. Like ''D. discoideum'', it exhibits a robust multicellu ...

'' Olive 1901 * '' Dictyostelium quercibrachium'' Cavender et al. 2002 * '' Dictyostelium robustum'' Hagiwara 1996 * '' Dictyostelium rosarium'' Raper & Cavender 1968 * '' Dictyostelium septentrionale'' Cavender 1978 * '' Dictyostelium sphaerocephalum'' (Oudem. 1885) Saccardo, Marchal & Marchal 1885 * '' Dictyostelium valdivianum'' Vadell et al. 2011

References

{{Taxonbar, from=Q17146891 Mycetozoa Amoebozoa genera Taxa named by Julius Oscar Brefeld