Astrephomene

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Astrephomene
Scientific classification OOjs UI icon edit-ltr.svg
(unranked): Viridiplantae
Division: Chlorophyta
Class: Chlorophyceae
Order: Chlamydomonadales
Family: Goniaceae
Genus: Astrephomene
Pocock
Species

Astrephomene is a genus of green algae in the family Goniaceae, order Chlamydomonadales. [1] [2] The genus was first described in 1937 by Pocock and named by Pockock in 1953 (Stein 1958). The genome of Astrephomene gubernaculifera has been sequenced. [3]

Contents

Taxonomy

It was formerly placed in the monotypic family Astrephomenaceae. Astrephomenaceae is now considered obsolete, and Astrephomene is now classified within the Goniaceae. [4]

Description

Astrephomene gubernaculifera is a colonial, flagellated volvocine green algae. It consists of 16, 32, 64 or 128 cells, 2 to 7 of which are small and oriented such that their flagella form a rudder (Stein 1958). Each cell is surrounded by a gelatinous matrix and contains an eyespot, two flagella and 1-3 contractile vacuoles at the anterior end.

Astrephomene gubernaculifera can reproduce sexually or asexually. During asexual reproduction of Astrephomene, rotation of daughter protoplasts occurs in conjunction with the movement of basal bodies during successive cell divisions, ending with the anterior end of all cells of the daughter colony outside after the first nuclear and cytoplasmic division. [5] This type of asexual reproduction is unique among the colonial volvocine green algae (Pocock 1953). By contrast, in Eudorina, protoplast rotation is lacking during successive divisions; a spheroidal colony is formed by means of inversion after successive divisions. Astrephomene gubernaculifera has two mating types that reproduce to form zygotes.

Schematic diagrams of the two mechanisms of spheroidal colony formation in the volvocine algae. In Astrephomene, rotation of daughter protoplasts occurs in conjunction with the movement of basal bodies during successive cell divisions. In Eudorina, protoplast rotation is lacking during successive divisions; a spheroidal colony is formed by means of inversion after successive divisions. Doi 10.1186-s12862 2016 794 Fig7 HTML.jpg
Schematic diagrams of the two mechanisms of spheroidal colony formation in the volvocine algae. In Astrephomene, rotation of daughter protoplasts occurs in conjunction with the movement of basal bodies during successive cell divisions. In Eudorina, protoplast rotation is lacking during successive divisions; a spheroidal colony is formed by means of inversion after successive divisions.

Evolution

Colony inversion is believed to have arisen twice in the order Chlamydomonadales. Spheroidal colony formation differs between the two lineages: rotation of daughter protoplasts during successive cell divisions in Astrephomene, and inversion after cell divisions in Eudorina. [5]

Schematic representation of the phylogenetic relationships of the volvocine algae and the parallel evolution of the spheroidal colony. Volvocine algae range from the unicellular Chlamydomonas to the multicellular Volvox through various intermediate forms and are used as a model for research into the evolution of multicellularity. The spheroidal colony is thought to have evolved twice independently within this group: once in the Volvocaceae, from Pandorina to Volvox, and the other in the genus Astrephomene. The phylogeny is based on previous reports. All drawings and photographs represent side views of individuals with anterior ends orienting toward the top of this figure. Doi 10.1186-s12862 2016 794 Fig1 HTML.jpg
Schematic representation of the phylogenetic relationships of the volvocine algae and the parallel evolution of the spheroidal colony. Volvocine algae range from the unicellular Chlamydomonas to the multicellular Volvox through various intermediate forms and are used as a model for research into the evolution of multicellularity. The spheroidal colony is thought to have evolved twice independently within this group: once in the Volvocaceae, from Pandorina to Volvox, and the other in the genus Astrephomene. The phylogeny is based on previous reports. All drawings and photographs represent side views of individuals with anterior ends orienting toward the top of this figure.

Habitats

Astrephomene gubernaculifera is often found in organically rich temporary pools, often in pasture ponds. It typically persists for 1–3 weeks after ponds are formed in beginning of the wet season (Pocock 1953).

It has been collected from South Africa, Australia and the United States (Pocock 1953).

Related Research Articles

<span class="mw-page-title-main">Chlorophyceae</span> Class of green algae

The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose.

<i>Volvox</i> Genus of algae

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. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Volvox diverged from unicellular ancestors approximately 200 million years ago.

<span class="mw-page-title-main">Volvocaceae</span> Family of algae

The Volvocaceae are a family of unicellular or colonial biflagellates, including the typical genus Volvox. The family was named by Ehrenberg in 1834, and is known in older classifications as the Volvocidae. All species are colonial and inhabit freshwater environments.

<span class="mw-page-title-main">Chlamydomonadales</span> Order of green algae

Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae. Chlamydomonadales can form planar or spherical colonies. These vary from Gonium up to Volvox. Each cell has two flagella, and is similar in appearance to Chlamydomonas, with the flagella throughout the colony moving in coordination.

<i>Acetabularia</i> Green algae genus, family Polyphysaceae

Acetabularia is a genus of green algae in the family Polyphysaceae. Typically found in subtropical waters, Acetabularia is a single-celled organism, but gigantic in size and complex in form, making it an excellent model organism for studying cell biology. In form, the mature Acetabularia resembles the round leaves of a nasturtium, is 4 to 10 centimetres tall and has three anatomical parts: a bottom rhizoid that resembles a set of short roots; a long stalk in the middle; and a top umbrella of branches that may fuse into a cap. Unlike other giant unicellular organisms, which are multinucleate, members of this genus possess a single nucleus located in the rhizoid, which allows the cell to regenerate completely if its cap is removed. The caps of two Acetabularia may also be exchanged, even from two different species. In addition, if a piece of the stem is removed, with no access to the nucleus in the rhizoid, this isolated stem piece will also grow a new cap.

<i>Pandorina</i> Genus of algae

Pandorina is a genus of green algae composed of 8, 16, or sometimes 32 cells, held together at their bases to form a sack globular colony surrounded by mucilage. The cells are ovoid or slightly narrowed at one end to appear keystone- or pear-shaped. Each cell has two flagella with two contractile vacuoles at their base, an eyespot, and a large cup-shaped chloroplast with at least one pyrenoid.

<i>Gonium</i> Genus of algae

Gonium is a genus of colonial algae, a member of the order Chlamydomonadales. Typical colonies have 4 to 16 cells, all the same size, arranged in a flat plate, with no anterior-posterior differentiation. 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 :

Gonium Mueller 1773: Colonies of 4-8-16 cells arranged in a flat quadrangular plate and embedded in a common gelatinous matrix or connected by broad gelatinous strands. Cells ovoid to pyriform, with a single cup-shaped chloroplast containing one pyrenoid. Each cell with two cilia of equal length, contractile vacuoles at the base of the cilia, and an eyespot. Four- and eight-celled colonies with the cilia on the same side ; sixteen-celled colonies with the four central cells having their cilia on the same side and the twelve marginal cells with radially arranged cilia.

Asexual reproduction by simultaneous division of all cells in the colony to form autocolonies, or by a formation of 2-4 zoospores in each cell.

Sexual reproduction isogamous, by a fusion of biciliatezoogametes.

<span class="mw-page-title-main">Chlamydomonadaceae</span> Family of algae

Chlamydomonadaceae is a family of algae within the order Chlamydomonadales. Traditionally, it has been defined as containing single-celled flagellates with a cell wall.

<i>Eudorina</i> Genus of algae

Eudorina is a paraphyletic genus in the volvocine green algae clade. Eudorina colonies consist of 16, 32 or 64 individual cells grouped together. Each individual cell contains flagella which allow the colony to move as a whole when the individual cells beat their flagella together. Description by GM Smith :

<i>Asterococcus</i> Genus of algae

Asterococcus is a genus of green algae in the order Chlamydomonadales. It is planktonic in freshwater ponds and lakes, or benthic within mires and swamps. It is a common and widespread genus, but is rarely abundant.

<i>Carteria</i> Genus of algae

Carteria is a genus of green algae in the family Chlamydomonadaceae. Carteria are similar in morphology to the common genus Chlamydomonas and differ by having four, rather than two, flagella at the vegetative stage.

<i>Chlainomonas</i> Genus of algae

Chlainomonas is a genus of algae in the family Chlamydomonadaceae. They are found in freshwater habitats or on snow, where they are one of the main algae responsible for causing watermelon snow.

<i>Lobomonas</i> Genus of algae

Lobomonas is a genus of green algae in the family Chlamydomonadaceae, found in freshwater habitats. Although it is widely distributed, it is a rare genus.

<i>Picocystis</i> Genus of algae

Picocystis is a monotypic genus of green algae, the sole species is Picocystis salinarum. It is placed within its own class, Picocystophyceae in the division Chlorophyta.

<i>Stephanosphaera</i> Genus of algae

Stephanosphaera is a genus of green algae in the family Haematococcaceae, containing the single species Stephanosphaera pluvialis. It forms colonies of flagellated cells. Although it was once placed in the family Volvocaceae, it is not closely related to them; its sister is the unicellular genus Balticola.

Spinoclosterium is a genus of green algae, specifically of the Closteriaceae. It is rare, but widely distributed in freshwater regions throughout the world.

<span class="mw-page-title-main">Goniaceae</span> Family of algae

Goniaceae is a family of algae in the order Chlamydomonadales, that includes the genera Astrephomene and Gonium. Members of the Goniaceae are distinguished from those of the Volvocaceae by having each cell surrounded by a tripartite boundary of the extracellular matrix, as opposed to the entire colony being surrounded by the tripartite boundary in Volvocaceae.

<i>Pediastrum duplex</i> Species of alga

Pediastrum duplex is a species of fresh water green algae in the genus Pediastrum. It is the type species of the genus Pediastrum.

Picochlorum oklahomense is a species of coccoid chlorophyte algae, the type species of its genus. It is broadly halotolerant, small, asexual and lacks chlorophyll b. The author of the name spelt the specific epithet "oklahomensis". AlgaeBase corrects this to the neuter form oklahomense, to agree with the genus name.

Kathleen "Kay" Margaret Cole was a Canadian phycologist, known as one of the world's leading experts in the cytology of marine algae. In 1998 the Canadian Botanical Society awarded her the George Lawson Medal for lifetime achievement.

References

  1. Nozaki, H.; Kuroiwa, T. (1992). "Ultrastructure of the extracellular matrix and taxonomy of Eudorina, Pleodorina and Yamagishiella gen. nov. (Volvocaceae, Chlorophyta)". Phycologia. 31 (6): 529–541. Bibcode:1992Phyco..31..529N. doi:10.2216/i0031-8884-31-6-529.1.
  2. See the NCBI webpage on Astrephomene. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information . Retrieved 2007-03-19.
  3. Yamashita, Shota; Yamamoto, Kayoko; Matsuzaki, Ryo; Suzuki, Shigekatsu; Yamaguchi, Haruyo; Hirooka, Shunsuke; Minakuchi, Yohei; Miyagishima, Shin-ya; Kawachi, Masanobu; Toyoda, Atsushi; Nozaki, Hisayoshi (2021-11-22). "Genome sequencing of the multicellular alga Astrephomene provides insights into convergent evolution of germ-soma differentiation". Scientific Reports. 11 (1): 22231. Bibcode:2021NatSR..1122231Y. doi:10.1038/s41598-021-01521-x. ISSN   2045-2322. PMC   8608804 . PMID   34811380.
  4. Nozaki, H.; Kuroiwa, T. (1992). "Ultrastructure of the extracellular matrix and taxonomy of Eudorina, Pleodorina and Yamagishiella gen. nov. (Volvocaceae, Chlorophyta)". Phycologia. 31 (6): 529–541. Bibcode:1992Phyco..31..529N. doi:10.2216/i0031-8884-31-6-529.1.
  5. 1 2 3 Yamashita, S.; Arakaki, Y.; Kawai-Toyooka, H.; Noga, A.; Hirono, M.; Nozaki, H. (2016). "Alternative evolution of a spheroidal colony in volvocine algae: Developmental analysis of embryogenesis in Astrephomene (Volvocales, Chlorophyta)". BMC Evolutionary Biology. 16 (1): 243. Bibcode:2016BMCEE..16..243Y. doi: 10.1186/s12862-016-0794-x . PMC   5103382 . PMID   27829356. Creative Commons by small.svg  This article incorporates textfrom this source, which is available under the CC BY 4.0 license.

Further reading

Scientific journals