Closterium
Closterium | |
---|---|
Closterium sp. | |
Scientific classification | |
(unranked): | Viridiplantae |
(unranked): | Charophyta |
Class: | Zygnematophyceae |
Order: | Desmidiales |
Family: | Closteriaceae |
Genus: | Closterium Nitzsch ex Ralfs, 1848 |
Species | |
See text. |
Closterium is a
Description
Closterium is a diverse genus consisting of solitary cells, each made of two identical halves called semicells. Usually they are microscopic, but the largest can become easily visible to the naked eye. Cells are many times longer than broad, and are variously elongate to lunate (crescent-shaped). The poles are rounded, truncated, or pointed. The surface of the cell may be smooth or decorated with various features, such as striations or punctae. The cell wall is transparent, but with age it may become dark brown due to accumulated iron and manganese compounds.[2] The cell nucleus is located in the middle of the cell. Each semicell contains a single axial chloroplast dotted with several pyrenoids.[4]
At either end of the cell, there is a generally a polar vacuole. The vacuoles often contain conspicuous barium sulfate crystals.[4]
Taxonomy
Closterium regulare was first described from Lower Normandy by Brebisson.[5]
Species
Closterium includes the following species:
- C. acerosum
- C. calosporum
- C. cornu
- C. ehrenbergii
- C. gracile
- C. incurvum
- C. littorale
- C. lunula
- C. moniliferum
- C. navicula
- C. peracerosum
- C. peracerosum-strigosum-littorale complex
- C. pleurodermatum
- C. pusillum
- C. selenastrum
- C. setaceum
- C. spinosporum
- C. tumidum
- C. venus
- C. wallichii
Reproduction
Asexual: binary fission from a partitioned parent cell.
Sexual: Conjugation to form a hypnozygote.
The Closterium peracerosum-strigosum-littorale (C. psl) complex is a
A homothallic strain of Closterium forms selfing zygospores via the conjugation of two sister gametangial cells derived from one vegetative cell.[7] Conjugation in the homothallic strain occurs mainly at low cell density and is regulated by an ortholog of a heterothallic sex-specific pheromone.
Although self-fertilization employs meiosis, it produces minimal genetic variability. Homothallism is thus a form of sex that is unlikely to be adaptively maintained by a benefit related to producing variability. However, homothallic meiosis may be maintained in Closterium peracerosum as an adaptation for surviving under stressful conditions such as growth in nitrogen depleted media at low cell density. A proposed adaptive benefit of meiosis is the promotion of homologous recombinational repair of DNA damages that can be caused by a stressful environment [8]
Habitats
Like other desmids, Closterium is found in
References
- ^ See the NCBI webpage on Closterium. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19.
- ^ ISBN 857656064X.
- ^ ISBN 978-1-118-91716-9.
- ^ ISBN 978-0-12-385876-4.
- ^ Carter, C.F. and Williamson, D.B. (2008) A rediscovered UK desmid: Closterium regulare Breb The Phycologist. Autumn 2008 No.75:24
- S2CID 1999634.
- PMID 20656896.
- PMID 27605505.
External links
- Guiry, M.D.; Guiry, G.M. "Closterium". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
- AlgaTerra database
- Index Nominum Genericorum