''Gonium'' (

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

: γωνία ''gonia'', "angle" or "corner") is a genus of colonial

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

, a member of the order

Chlamydomonadales Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae.See the NCBIbr>webpage on Chlamydomonadales Data extracted from the Chlamydomonadales can form planar o ...

. The genus was first described by

Otto Friedrich Müller Otto Friedrich Müller, also known as Otto Friedrich Mueller (2 November 1730 – 26 December 1784) was a Denmark, Danish natural history, naturalist and scientific illustrator. Biography Müller was born in Copenhagen. He was educated for the ch ...

in 1773, and is among the most common types of algae found in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

habitats. It has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

. Typical colonies of ''Gonium'' consist of 4 to 16 cells arranged in a flat plate. ''Gonium'' is capable of both

asexual Asexual or Asexuals may refer to: *Asexual reproduction **Asexual reproduction in starfish *Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity. **Gray asexuality, the spectrum between asexualit ...

and

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

. Along with other algae such as ''

Volvox ''Volvox'' is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. ''Volvox'' species form spherical colonies of up to 50,000 cells, and for this reason they are sometimes called globe algae. First reported by Antonie van L ...

'', ''

Eudorina ''Eudorina'' is a genus of green algae in the family Volvocaceae, containing about seven species. It has a cosmopolitan distribution in freshwater habitats. Description ''Eudorina'' colonies typically consist of 16, 32 or 64 cells, each of wh ...

'' and ''

Chlamydomonas ''Chlamydomonas'' ( ) is a genus of green algae consisting of about 150 species of unicellular organism, unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". ''Chlamydom ...

'', it is a

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

for studying the origins and evolution of

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

Description

''Gonium'' consists of flat, planar colonies of four to 32 cells, all identical with the colony having no anterior-posterior differentiation. In one species ''Gonium dispersum'', single cells may also be found. In a colony of 16 cells, four are in the center, and the other 12 are on the four sides, three each. A description by G.M. Smith (1920, p. 94):Smith, GM. Phytoplankton of Inland Lakes of Wisconsin, Part I, Wisconsin Geological and Natural History Survey, Madison, WI. (1920).

Life cycle

''Gonium'' being evolutionarily related to ''

'' has a life cycle that is derivative of that of ''Chlamydomonas''. ''Gonium'' cells grow asexually as colonies of either 4, 8 or 16 colonial cells. Cell and colony growth of ''Gonium'' is uncoupled from cell division just like ''Chlamydomonas'' and each cell within the colony divides by multiple-fission. Thus, each cell within the colony will divide 2, 3 or 4 times, thus producing 2^"n" daughter cells, or 4, 8 or 16 cells within the colony. Unlike ''Chlamydomonas'' where each of the daughter cells separate from each other, ''Gonium'' daughter cells remain attached to each other in their ECM. The sexual cycle of ''Gonium'' is also very similar to that of ''Chlamydomonas''. The sexual program of ''Gonium'' is induced by nitrogen deprivation where each vegetative cell within the colony differentiates in gametes. ''Gonium'' gametes are

isogamous Isogamy is a form of sexual reproduction that involves gametes of the same morphology (indistinguishable in shape and size), and is found in most unicellular eukaryotes. Because both gametes look alike, they generally cannot be classified as ma ...

, or equal-sized, and unicellular. Thus unicellular ''Gonium'' gametes break apart from the multicellular colonies when the sexual program is initiated. Also like ''Chlamydomonas'', there are two "sexes", plus or minus controlled by a genes homologous to those found in ''

'' and ''

''.

Evolution

The genus ''Gonium'' represents species closely related to single celled ''

'' and multicellular differentiated ''

''. The order

Volvocales Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae.See the NCBIbr>webpage on Chlamydomonadales Data extracted from the Chlamydomonadales can form planar or ...

has long been a well recognized model system for the study of multicellular evolution. ''Gonium'' and the family Tetrabaenaceae contain species representative of colony formation among unicells. ''Gonium'' morphology of colonies of alike cells suggest it is more genetically similar to ''

'' than ''

'', a fact confirmed by phylogenetic analysis. The

have been hypothesized to have evolved in twelve discrete steps. Gonium represents the first six evolutionary steps of multicellularity; (1) incomplete cytokinesis, (2) partial inversion, (3) rotation of the basal bodies, (4) organismal polarity, (5) transformation of the cell wall into extra-cellular matrix (ECM), (6) genetic control of cell number. Although the exact order and progression through David Kirk's twelve steps of multicellular evolution are probably not necessarily linear and each occurs more dynamically than originally thought.

Taxonomy

''Gonium'' is the

type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...

of the family Goniaceae, which includes one other genus, ''

Astrephomene ''Astrephomene'' is a genus of green algae in the family Goniaceae, order Chlamydomonadales. The genus was first discovered in 1937 by Mary Pocock and later named by Pocock in 1953. The name comes from the Classical Greek roots ''a-'' (meaning "n ...

''. The two genera are characterized by having similar extracellular matrix

ultrastructure Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a c ...

. The similar genera '' Tetrabaena'' and '' Basichlamys'' were previously included in ''Gonium''. These genera differ in reproductive and vegetative characters, such as only producing four-celled colonies. Species of ''Gonium'' are distinguished based on morphological characters, such as the typical number of cells in a colony, shape of cells and their extracellular matrix, number of pyrenoids, and arrangement of cells within the colony. The following is a

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

based on the

ITS ITS, its or it's may refer to: Language * It's, an English contraction of ''it is'' or ''it has'' * Its (pronoun), the possessive form of the pronoun it * Itsekiri language (ISO 639 language code its), a language found in Nigeria and the Niger De ...

region of nuclear

ribosomal DNA The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...

(not all species are included):

References

External links

Gonium
- Description with pictures

- Research overview of Dr. Richard Michod at the University of Arizona who studies multicellular evolution and whose lab published a detailed phylogenetic tree of the

VIP
- The Volvocales Information Project led by Dr. Aurora M. Nedelcu at University of New Brunswick
Olson Lab
- Dr. Bradley Olson at Kansas State University who studies multicellular evolution with methods for growing Gonium

- Dr. Hisayoshi Nozaki at the University of Tokoyo who studies multicellular evolution and has cultured many

strains, including Gonium
Hallman Lab
- Dr. Armin Hallman at Bielefeld University whose lab developed a method for transforming Gonium *
UTEX
- The UTEX algal culture collection which houses many Gonium strains including pictures
CCAP
- The CCAP algal culture collection which houses many Gonium strains including pictures {{Taxonbar, from=Q310242 Chlamydomonadales genera Chlamydomonadales