# Astrephomene > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Astrephomene > Markdown URL: https://mediated.wiki/source/Astrephomene.md > Source: https://en.wikipedia.org/wiki/Astrephomene > Source revision: 1336673829 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) ***Astrephomene*** is a [genus](/source/Genus) of [green algae](/source/Green_algae) in the family [Goniaceae](/source/Goniaceae), order [Chlamydomonadales](/source/Chlamydomonadales).[1][2] The genus was first discovered in 1937 by [Mary Pocock](/source/Mary_Pocock) and later named by Pocock in 1953.[3] The name comes from the [Classical Greek](/source/Classical_Greek) roots *a-* (meaning "not") and *strephomene* (meaning "turning itself"), referring to its mode of reproduction.[3][4] To date, the genus contains two species.[5] *Astrephomene* is a member of the [volvocine algae](/source/Chlamydomonadales), a group of algae that are a [model organism](/source/Model_organism). Volvocine algae are used to study the origins and evolution of multicellularity. The genome of *[Astrephomene gubernaculifera](/source/Astrephomene_gubernaculifera)* has been sequenced.[6] ## Description *Astrephomene* is a colonial, flagellated [green alga](/source/Green_alga), consisting of 16, 32, 64 or 128 cells arranged at the periphery of a gelatinous matrix.[5] Two to seven cells are somatic cells (also termed rudder cells); they are small and oriented such that their flagella form a rudder.[3][5] Cells are spherical or lenticular (lens-shaped), and each cell contains an [eyespot](/source/Eyespot_apparatus), two flagella, several contractile vacuoles at the anterior end, and a large cup-shaped [chloroplast](/source/Chloroplast). Each cell is surrounded by a gelatinous sheath and adjacent cells are attached to each other by their sheaths, forming a hollow, ovoid or spheroidal colony.[5] *Astrephomene gubernaculifera* can reproduce sexually or asexually. During [asexual reproduction](/source/Asexual_reproduction), 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.[7] This type of asexual reproduction is unique among the colonial volvocine green algae.[4] By contrast, in *Eudorina*, protoplast rotation is lacking during successive divisions; a spheroidal colony is formed by means of inversion after successive divisions. In sexual reproduction, *Astrephomene* has two identical mating types (i.e. is [isogamous](/source/Isogamous)); these fuse to form zygotes.[5] ## 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.[4] It has been collected from South Africa, Australia, the United States,[4] and Japan.[8] ## Taxonomy *Astrephomene* was formerly placed in the monotypic family Astrephomenaceae. Astrephomenaceae is now considered obsolete, and the genus is now classified within the Goniaceae.[9] *Astrephomene* consists of two species, *[Astrephomene gubernaculifera](/source/Astrephomene_gubernaculifera)* and *[Astrephomene perforata](/source/Astrephomene_perforata)*. The two species differ in the morphology of the cells, such as the shape of their cellular sheaths and presence of pyrenoids.[8] ## Evolution [Colony inversion](/source/Colony_inversion) is believed to have arisen twice in the order [Chlamydomonadales](/source/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*.[7] ## 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](https://ui.adsabs.harvard.edu/abs/1992Phyco..31..529N). [doi:10.2216/i0031-8884-31-6-529.1](https://doi.org/10.2216/i0031-8884-31-6-529.1) 1. See the [NCBI](/source/National_Center_for_Biotechnology_Information) [webpage on Astrephomene](https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=47772). Data extracted from the ["NCBI taxonomy resources"](https://ftp.ncbi.nih.gov/pub/taxonomy/). [National Center for Biotechnology Information](/source/National_Center_for_Biotechnology_Information). Retrieved 2007-03-19. 1. Stein, Janet R. (1958). "A Morphological Study of *Astrephomene gubernaculifera* and *Volvulina steinii*". *American Journal of Botany*. **45** (5): 388–397. [doi:10.1002/j.1537-2197.1958.tb13142.x](https://doi.org/10.1002/j.1537-2197.1958.tb13142.x) 1. Pocock, M. A. (1954). "Two multicellular motile green algae, *Volvulina* Playfair and *Astrephomene*, a new genus". *Transactions of the Royal Society of South Africa*. **34** (1): 103–127. [Bibcode:1954TRSSA..34..103P](https://ui.adsabs.harvard.edu/abs/1954TRSSA..34..103P). [doi:10.1080/00359195409518981](https://doi.org/10.1080/00359195409518981) 1. 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](https://ui.adsabs.harvard.edu/abs/2021NatSR..1122231Y). [doi:10.1038/s41598-021-01521-x](https://doi.org/10.1038/s41598-021-01521-x). [ISSN 2045-2322](https://www.worldcat.org/issn/2045-2322). [PMC 8608804](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8608804). [PMID 34811380](https://pubmed.ncbi.nlm.nih.gov/34811380) 1. 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](https://ui.adsabs.harvard.edu/abs/2016BMCEE..16..243Y). [doi:10.1186/s12862-016-0794-x](https://doi.org/10.1186/s12862-016-0794-x). [PMC 5103382](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103382). [PMID 27829356](https://pubmed.ncbi.nlm.nih.gov/27829356) 1. Nozaki, Hisayoshi (1983). "Morphology and taxonomy of two species of Astrephomene (Chlorophyta, Volvocales) in Japan". *Journal of Japanese Botany*. **58**. [doi:10.51033/jjapbot.58_11_7555](https://doi.org/10.51033/jjapbot.58_11_7555) 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](https://ui.adsabs.harvard.edu/abs/1992Phyco..31..529N). [doi:10.2216/i0031-8884-31-6-529.1](https://doi.org/10.2216/i0031-8884-31-6-529.1) ## Further reading ### Scientific journals - Nozaki H, Onishi K, Morita E (2002). "Differences in pyrenoid morphology are correlated with differences in the rbcL genes of members of the Chloromonas lineage (Volvocales, Chlorophyceae)". *J Mol Evol*. **55** (4): 414–430. [Bibcode:2002JMolE..55..414N](https://ui.adsabs.harvard.edu/abs/2002JMolE..55..414N). [doi:10.1007/s00239-002-2338-9](https://doi.org/10.1007/s00239-002-2338-9). [PMID 12355262](https://pubmed.ncbi.nlm.nih.gov/12355262). [S2CID 19862929](https://api.semanticscholar.org/CorpusID:19862929) --- Adapted from the Wikipedia article [Astrephomene](https://en.wikipedia.org/wiki/Astrephomene) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Astrephomene?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.