![Haeckel Mycetozoa](https://upload.wikimedia.org/wikipedia/commons/9/9d/Haeckel_Mycetozoa.jpg)
Slime mold or slime mould is an informal name given to several kinds of unrelated
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 ...
organisms with a life cycle that includes a free-living
single-celled stage and the formation of spores. Spores are often produced in macroscopic multicellular or
multinucleate
Multinucleate cells (also known as multinucleated or polynuclear cells) are eukaryotic cells that have more than one nucleus per cell, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordinat ...
fruiting bodies which may be formed through aggregation or fusion. Slime molds were formerly classified as
fungi
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 ...
but are no longer considered part of that
kingdom
Kingdom commonly refers to:
* A monarchy ruled by a king or queen
* Kingdom (biology), a category in biological taxonomy
Kingdom may also refer to:
Arts and media Television
* ''Kingdom'' (British TV series), a 2007 British television drama s ...
.
Although not forming a single
monophyletic clade, they are grouped within the
paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
group
Protista
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 ...
.
More than 900 species of slime mold occur globally. Their common name refers to part of some of these organisms' life cycles where they can appear as gelatinous "slime". This is mostly seen with the
Myxogastria
Myxogastria/Myxogastrea (myxogastrids, International Code of Zoological Nomenclature, ICZN) or Myxomycetes (International Code of Nomenclature for algae, fungi, and plants, ICN), is a Class (biology), class of slime molds that contains 5 o ...
, which are the only
macroscopic
The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic.
Overview
When applied to physical phenomena a ...
slime molds. Most slime molds are smaller than a few centimetres, but some species may reach sizes up to several square metres and masses up to 20 kilograms.
They feed on
microorganisms that live in any type of dead plant material. They contribute to the decomposition of dead vegetation, and feed on
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
and
fungi
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 ...
. For this reason, slime molds are usually found in
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
,
lawn
A lawn is an area of soil-covered land planted with grasses and other durable plants such as clover which are maintained at a short height with a lawnmower (or sometimes grazing animals) and used for aesthetic and recreational purposes. ...
s, and on the
forest floor
The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stages ...
, commonly on
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
logs. In
tropical areas they are also common on
inflorescences
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
and
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
s, and in aerial situations (e.g., in the canopy of trees). In urban areas, they are found on
mulch
A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area.
A mu ...
or in the
leaf mold
Leaf mold (spelled leaf mould outside of the United States) is the compost produced by decomposition of shaded deciduous shrub and tree leaves, primarily by fungal breakdown in a slower cooler manner as opposed to the bacterial degradation of lea ...
in
rain gutter
A rain gutter, eavestrough, eaves-shoot or surface water collection channel is a component of a water discharge system for a building. It is necessary to prevent water dripping or flowing off roofs in an uncontrolled manner for several reasons ...
s, and also grow in air conditioners, especially when the drain is blocked.
Taxonomy
Older classification
Slime molds, as a group, are
polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...
. They were originally represented by the subkingdom Gymnomycota in the
Fungi
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 ...
kingdom and included the defunct phyla
Myxomycota,
Acrasiomycota
The family Acrasidae (ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
, and
Labyrinthulomycota
The Labyrinthulomycetes (ICBN) or Labyrinthulea ( ICZN) are a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the laby ...
. Slime molds are now divided among several supergroups, none of which is included in the kingdom Fungi.
Slime molds can generally be divided into two main groups.
*A
plasmodial
A plasmodium is a living structure of cytoplasm that contains many nuclei, rather than being divided into individual cells each with a single nucleus.
Plasmodia are best known from slime molds, but are also found in parasitic Myxosporea, and so ...
slime mold is enclosed within a single membrane without walls and is one large cell. This "supercell" (a
syncytium
A syncytium (; plural syncytia; from Greek: σύν ''syn'' "together" and κύτος ''kytos'' "box, i.e. cell") or symplasm is a multinucleate cell which can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus) ...
) is essentially a bag of
cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
containing thousands of individual nuclei. See
heterokaryosis
A heterokaryon is a multinucleate cell that contains genetically different nuclei. Heterokaryotic and heterokaryosis are derived terms. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual ...
.
*By contrast, cellular slime molds spend most of their lives as individual unicellular
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 ...
s, but when a chemical signal is secreted, they assemble into a cluster that acts as one organism.
Modern classification
In more strict terms, slime molds comprise the
mycetozoan
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 dictyoste ...
group of the
amoebozoa
Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported classi ...
. Mycetozoa include the following three groups:
*
Myxogastria
Myxogastria/Myxogastrea (myxogastrids, International Code of Zoological Nomenclature, ICZN) or Myxomycetes (International Code of Nomenclature for algae, fungi, and plants, ICN), is a Class (biology), class of slime molds that contains 5 o ...
or myxomycetes:
syncytial
A syncytium (; plural syncytia; from Greek: σύν ''syn'' "together" and κύτος ''kytos'' "box, i.e. cell") or symplasm is a multinucleate cell which can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus) ...
, plasmodial, or acellular slime molds
*
Dictyosteliida or dictyostelids: cellular slime molds
*
Protosteloids: amoeboid slime molds that form fruiting bodies
Even at this level of classification there are conflicts to be resolved. Recent molecular evidence shows that, while the first two groups are likely to be monophyletic, the protosteloids are likely to be polyphyletic. For this reason, scientists are currently trying to understand the relationships among these three groups.
![Schleimpilz Urwald Sababurg](https://upload.wikimedia.org/wikipedia/commons/8/87/Schleimpilz_Urwald_Sababurg.jpg)
The most commonly encountered are the
Myxogastria
Myxogastria/Myxogastrea (myxogastrids, International Code of Zoological Nomenclature, ICZN) or Myxomycetes (International Code of Nomenclature for algae, fungi, and plants, ICN), is a Class (biology), class of slime molds that contains 5 o ...
. A common slime mold that forms tiny brown tufts on rotting logs is ''
Stemonitis''. Another form, which lives in rotting logs and is often used in research, is ''
Physarum polycephalum
''Physarum polycephalum'', an acellular slime mold or myxomycete popularly known as "the blob", is a protist with diverse cellular forms and broad geographic distribution. The “acellular” moniker derives from the plasmodial stage of the li ...
''. In logs, it has the appearance of a slimy web-work of yellow threads, up to a few feet in size. ''
Fuligo
''Fuligo'' is a widespread genus of plasmodial slime mold in the family Physaraceae. These organisms are protozoans rather than fungi, but for historical reasons are sometimes treated as part of mycology.
Species
The following species are acce ...
'' forms yellow crusts in mulch.
The ''
Dictyosteliida'' – cellular slime molds – are distantly related to the plasmodial slime molds and have a very different lifestyle. Their amoebae do not form huge
coenocyte
A coenocyte () is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes insid ...
s, and remain individual. They live in similar habitats and feed on microorganisms. When food is depleted and they are ready to form sporangia, they do something radically different. They release signal molecules into their environment, by which they find each other and create swarms. These
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 or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...
e then join up into a tiny multicellular slug-like coordinated creature, which crawls to an open lit place and grows into a fruiting body. Some of the amoebae become spores to begin the next generation, but some of the amoebae sacrifice themselves to become a dead stalk, lifting the spores up into the air.
The
protosteloids have characters intermediate between the previous two groups, but they are much smaller, the fruiting bodies only forming one to a few
spores
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
.
Non-amoebozoan slime molds include:
*
Acrasid
The family Acrasidae (International Code of Zoological Nomenclature, ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the Excavata, excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning ...
s (order Acrasida): slime molds which belong to the
Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Most Percolozoa are found as bacterivores in soil, fresh water and occasionall ...
within the supergroup
Excavata
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free- ...
. They have a similar life style to
Dictyostelids
The dictyostelids (Dictyostelia/Dictyostelea, ICZN, or Dictyosteliomycetes, ICBN) are a group of cellular slime molds, or social amoebae.
Multicellular behavior
When food (normally bacteria) is readily available dictyostelids behave as individ ...
, but their amoebae behave differently, having eruptive pseudopodia. They used to belong to the defunct
phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...
of Acrasiomycota.
*
Plasmodiophorid
The Phytomyxea are a class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. They are divided into the orders Plasmodiophorida ( ICZN, or Plasmodiophoromycota, ICBN) and Ph ...
s (order Plasmodiophorida):
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
protists which belong to the supergroup
Rhizaria
The Rhizaria are an ill-defined but species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are all non-photosynthethic, but many forami ...
. They can cause
cabbage club root disease and
powdery scab tuber disease. The Plasmodiophorids also form
coenocyte
A coenocyte () is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes insid ...
s, but are internal parasites of plants (e.g., club root disease of cabbages).
*
Labyrinthulomycota
The Labyrinthulomycetes (ICBN) or Labyrinthulea ( ICZN) are a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the laby ...
: slime nets, which belong to the superphylum
Heterokonta
Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which a ...
as the class Labyrinthulomycetes. They are marine and form labyrinthine networks of tubes in which amoeba without
pseudopod
A pseudopod or pseudopodium (plural: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filament ...
s can travel.
* ''
Fonticula
''Fonticula'' is a genus of cellular slime mold which forms a fruiting body in a volcano shape. As long ago as 1979 it has been known to not have a close relationship with either the Dictyosteliida or the Acrasidae, the two well-established gro ...
'' is a cellular slime mold that forms a fruiting body in a "volcano" shape. ''Fonticula'' is not closely related to either the Dictyosteliida or the Acrasidae. A 2009 paper finds it to be related to ''
Nuclearia
''Nuclearia'' is a nucleariid
Nucleariida is a group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially similar vampyrellids mainly by having mitochondria with discoid c ...
'', which in turn is related to
fungi
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 ...
.
Life cycle
Cellular slime molds
Many slime molds, mainly the "cellular" slime molds, do not spend most of their time in this state. When food is abundant, these slime molds exist as single-celled organisms. When food is in short supply, many of these single-celled organisms will congregate and start moving as a single body. In this state they are sensitive to airborne chemicals and can detect food sources. They can readily change the shape and function of parts, and may form stalks that produce fruiting bodies, releasing countless spores, light enough to be carried on the wind or hitch a ride on passing animals.
Reproduction of ''Dictyostelium discoideum''
''
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 ...
'' is another species of slime mold that has many different mating types. When this organism has entered the stage of reproduction, it releases an attractant, called ''
acrasin Each species of slime mold has its own specific chemical messenger, which are collectively referred to as acrasins. These chemicals signal that many individual cells aggregate to form a single large cell or plasmodium. One of the earliest acrasins t ...
''. Acrasin is made up of
cyclic adenosine monophosphate
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 ...
, or cyclic AMP. Cyclic AMP is crucial in passing hormone signals between reproductive cells.
When it comes time for the cells to fuse, ''Dictyostelium discoideum'' has mating types of its own that dictate which cells are compatible with each other. A scientific study demonstrated the compatibility of eleven mating types of ''Dictyostelium discoideum'' by monitoring the formation of macrocysts, concluding that cell contact between the compatible mating types needs to occur before macrocysts can form.
Plasmodial slime molds
Plasmodial slime molds begin life as
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 or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...
-like
cells. These unicellular amoebae are commonly
haploid and feed on
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. These amoebae can mate if they encounter the correct mating type and form
zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism.
In multicellula ...
s that then grow into
plasmodia. These contain many
nuclei without
cell membranes between them, and can grow to meters in size. The species ''
Fuligo septica
''Fuligo septica'' is a species of slime mold, and a member of the class Myxomycetes. It is commonly known as scrambled egg slime, or flowers of tan because of its peculiar yellowish appearance. It is also known as dog vomit slime mold, and is ...
'' is often seen as a slimy yellow network in and on rotting logs. The amoebae and the plasmodia engulf microorganisms.
The plasmodium grows into an interconnected network of protoplasmic strands.
Within each protoplasmic strand, the cytoplasmic contents rapidly stream. If one strand is carefully watched for about 50 seconds, the cytoplasm can be seen to slow, stop, and then reverse direction. The streaming protoplasm within a plasmodial strand can reach speeds of up to 1.35 mm per second, which is the fastest rate recorded for any microorganism. Migration of the plasmodium is accomplished when more protoplasm streams to advancing areas and protoplasm is withdrawn from rear areas. When the food supply wanes, the plasmodium will migrate to the surface of its substrate and transform into rigid fruiting bodies. The fruiting bodies or
sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...
are what are commonly seen. They superficially look like fungi or molds but are not related to the true fungi. These sporangia will then release spores which hatch into amoebae to begin the life cycle again.
In ''
Myxogastria
Myxogastria/Myxogastrea (myxogastrids, International Code of Zoological Nomenclature, ICZN) or Myxomycetes (International Code of Nomenclature for algae, fungi, and plants, ICN), is a Class (biology), class of slime molds that contains 5 o ...
'', the plasmodial portion of the life cycle only occurs after
syngamy, which is the fusion of cytoplasm and
nuclei of myxoamoebae or swarm cells. The diploid zygote becomes a
multinucleate
Multinucleate cells (also known as multinucleated or polynuclear cells) are eukaryotic cells that have more than one nucleus per cell, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordinat ...
d plasmodium through multiple nuclear divisions without further cell division. ''Myxomycete'' plasmodia are multinucleate masses of
protoplasm that move by cytoplasmic streaming. In order for the plasmodium to move, cytoplasm must be diverted towards the leading edge from the lagging end. This process results in the plasmodium advancing in fan-like fronts. As it moves, plasmodium also gains nutrients through the
phagocytosis
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 ...
of bacteria and small pieces of organic matter.
The plasmodium also has the ability to subdivide and establish separate plasmodia. Conversely, separate plasmodia that are genetically similar and compatible can fuse together to create a larger plasmodium. If conditions become dry, then the plasmodium will form a sclerotium, essentially a dry and dormant state. If conditions become moist again, then the sclerotium absorbs water and an active plasmodium is restored. When the food supply wanes, the ''Myxomycete'' plasmodium will enter the next stage of its life cycle forming haploid
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s, often in a well-defined
sporangium
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...
or other spore-bearing structure.
Reproduction of ''Physarum polycephalum''
Slime molds are isogamous organisms, which means their reproductive cells are all the same size. There are over 900 species of slime molds that exist today.
''Physarum polycephalum'' is one species that has three reproductive
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s – ''mat''A, ''mat''B, and ''mat''C. The first two types have thirteen separate variations. ''Mat''C, however, only has three variations. Each reproductively mature slime mold contains two copies of each of the three reproductive genes.
When ''P. polycephalum'' is ready to make its reproductive cells, it grows a bulbous extension of its body to contain them.
Each cell is created with a random combination of the genes that the slime mold contains within its
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
. Therefore, it can create cells with up to eight different gene types. Once these cells are released, they are independent and tasked with finding another cell it is able to fuse with. Other ''P. polycephalum'' may contain different combinations of the ''mat''A, ''mat''B, and ''mat''C genes, allowing over 500 possible variations. It is advantageous for organisms with this type of reproductive cell to have many mating types because the likelihood of the cells finding a partner is greatly increased. At the same time, the risk of inbreeding is drastically reduced.
Behavior
Similarity to Neural Systems
Slime molds share some similarities with neural systems in animals. The membranes of both slime molds and neural cells contains receptor sites, which alter electrical properties of the membrane when it is bound. Therefore, some studies on the early evolution of animal neural systems are inspired by slime molds.
When a slime mold mass or mound is physically separated, the cells find their way back to re-unite. Studies on ''
Physarum polycephalum
''Physarum polycephalum'', an acellular slime mold or myxomycete popularly known as "the blob", is a protist with diverse cellular forms and broad geographic distribution. The “acellular” moniker derives from the plasmodial stage of the li ...
'' have even shown an ability to learn and predict periodic unfavorable conditions in laboratory experiments.
John Tyler Bonner
John Tyler Bonner (May 12, 1920 – February 7, 2019) was an American biologist who was a professor in the Department of Ecology and Evolutionary Biology at Princeton University. He was a pioneer in the use of cellular slime molds to understand ...
, a professor of ecology known for his studies of slime molds, argues that they are "no more than a bag of amoebae encased in a thin slime sheath, yet they manage to have various behaviors that are equal to those of animals who possess muscles and nerves with ganglia – that is, simple brains."
Traffic System Inspirations
Atsushi Tero of
Hokkaido University
, or , is a Japanese national university in Sapporo, Hokkaido. It was the fifth Imperial University in Japan, which were established to be the nation's finest institutions of higher education or research. Hokkaido University is considered ...
grew ''Physarum'' in a flat wet dish, placing the mold in a central position representing Tokyo and oat flakes surrounding it corresponding to the locations of other major cities in the Greater Tokyo Area. As ''Physarum'' avoids bright light, light was used to simulate mountains, water and other obstacles in the dish. The mold first densely filled the space with plasmodia, and then thinned the network to focus on efficiently connected branches. The network strikingly resembled Tokyo's rail system.
Slime mold ''P. polycephalum'' was also used by
Andrew Adamatzky
Andrew Adamatzky is a British computer scientist, who is a Director of the Unconventional Computing Laboratory and Professor in Unconventional Computing at the Department of Computer Science and Creative Technology, University of the West of Engl ...
from the University of the West of England and his colleagues world-wide in experimental laboratory approximations of motorway networks of 14 geographical areas: Australia, Africa, Belgium, Brazil, Canada, China, Germany, Iberia, Italy, Malaysia, Mexico, the Netherlands, UK and US.
The filamentary structure of slime molds such as ''P. polycephalum'' forming a network to food sources is similar to the large scale
galaxy filament
In cosmology, galaxy filaments (subtypes: supercluster complexes, galaxy walls, and galaxy sheets) Boris V. Komberg, Andrey V. Kravtsov, Vladimir N. Lukash; "The search and investigation of the Large Groups of Quasars" ; ;R.G. Clowes; "Large Qu ...
structure of the
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...
. This observation has led astronomers to use simulations based on the behaviour of slime molds to inform their search for
dark matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not a ...
.
Chemical signals
The chemicals that aggregate slime molds are called
acrasin Each species of slime mold has its own specific chemical messenger, which are collectively referred to as acrasins. These chemicals signal that many individual cells aggregate to form a single large cell or plasmodium. One of the earliest acrasins t ...
s. The first acrasin to be discovered was
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 ...
in ''Dictyostelium discoideum''. During the aggregation phase of their life cycle, ''Dictyostelium discoideum'' amoebae communicate with each other by traveling waves of cAMP. There is an amplification of cAMP when they aggregate. In 2019, a research done by
University of Tokyo
, abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project by ...
finds out that while pre-stalk cells move toward cAMP, pre-spore cells, however, ignored cAMP.
The acrasin for ''Polysphondylium violaceum'' has been purified in 1983. It is a
dipeptide A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiologicall ...
that has been named glorin. Its major components are the
amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
,
glutamic acid and
ornithine
Ornithine is a non-proteinogenic amino acid that plays a role in the urea cycle. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency. The radical is ornithyl.
Role in urea cycle
L-Ornithine is one of the produ ...
. An
amino group
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...
(NH3) and a
carboxyl group
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...
(COOH) of the glutamic acid are blocked respectively by a propionyl group and an
ethyl ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are ...
. An amino group on the ornithine molecule is blocked by a
lactam
A lactam is a cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words ''lactone'' + ''amide''.
Nomenclature
Greek prefixes in alphabetical order indicate ring size:
* α-Lactam (3-atom rings)
* β-Lacta ...
ring. Both cyclic AMP and glorin are small molecules.
See also
*
Sorocarp
A sorocarp (from the Greek word ''soros'' "a heap" + ''karpos'' "fruit") is the fruiting body characteristic of certain cellular slime moulds (e.g., Dictyosteliida). Each sorocarp consists of both a sorophore (stalk) and a sorus.Lawrence, E. 2005 ...
*
Swarming motility
*
Water mold
Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result ...
References
Further reading
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External links
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{{Eukaryota, state = collapsed
Common names of organisms
Eukaryotes