Cyanidiophyceae

Cyanidiophyceae is a class of unicellular red algae within subdivision Cyanidiophytina, and contain a single plastid, one to three mitochondria, a nucleus, a vacuole, and floridean starch.^[1] Pyrenoids are absent.^[2] Most are extremophiles inhabiting acid hot springs. They originated in extreme environments with high temperatures and low pH, which allowed them to occupy ecological niches without any competition.^[3] While still found in extreme environments, they have also adapted to live along streams, in fissures in rock walls and in soil, but usually prefer relatively high temperatures. They have never been found in basic freshwater or seawater habitats.^[4] The main photosynthetic pigment is C-phycocyanin. Reproduction is asexual by binary fission or formation of endospores.^[5] The group, consisting of a single order (Cyanidiales), split off from the other red algae more than a billion years ago. Three families, four genera, and nine species are known, but the total number of species is probably higher. They are primarily photoautotrophic, but heterotrophic and mixotrophic growth also occurs. After the first massive gene loss in the common ancestor of all red algae, where ca. 25% of the genes were lost, a second gene loss occurred in the ancestor of Cyanidiophyceae, where additional 18% of the genes were lost.^[6] Since then, some gene gains and minor gene losses have taken place independently in the Cyanidiaceae and Galdieriaceae, leading to genetic diversification between the two groups, with Galdieriaceae occupying more diverse and varied niches in extreme environments than Cyanidiaceae.^[7]

Cyanidiophyceae
Cyanidium sp.
Scientific classification
Clade:	Archaeplastida
Division:	Rhodophyta
Subdivision:	Cyanidiophytina
Class:	Cyanidiophyceae T.Christensen
Families
Cyanidiaceae Galdieriaceae

References

1. Seckbach, Joseph; Chapman, David J. (30 August 2010). Red Algae in the Genomic Age. Springer. p. 250. ISBN 978-90-481-3794-7. Retrieved 31 January 2011.
2. Barrett, James; Girr, Philipp; MacKinder, Luke C. M. (April 2021). "Pyrenoids: CO2-fixing phase separated liquid organelles". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1868 (5). doi:10.1016/j.bbamcr.2021.118949. PMID 33421532.
3. Lee, Robert Edward (2018). Phycology. Cambridge University Press. ISBN 978-1-107-55565-5.
4. Levine, Ira A.; Fleurence, Joël (2018). Microalgae in Health and Disease Prevention. Academic Press. ISBN 978-0-12-811406-3.
5. Yoon, Hwan Su; Muller, Kirsten M.; Sheath, Robert G.; Ott, Franklyn D.; Bhattacharya, Debashish (April 2006). "Defining the Major Lineages of Red Algae (Rhodophyta)1". Journal of Phycology. 42 (2): 482–492. Bibcode:2006JPcgy..42..482Y. doi:10.1111/j.1529-8817.2006.00210.x. S2CID 27377549.
6. Van Etten, Julia; Cho, Chung Hyun; Yoon, Hwan Su; Bhattacharya, Debashish (2023). "Extremophilic red algae as models for understanding adaptation to hostile environments and the evolution of eukaryotic life on the early earth". Seminars in Cell & Developmental Biology. 134: 4–13. doi:10.1016/j.semcdb.2022.03.007. PMID 35339358.
7. Cho, Chung Hyun; Park, Seung In; Huang, Tzu-Yen; Lee, Yongsung; Ciniglia, Claudia; Yadavalli, Hari Chandana; Yang, Seong Wook; Bhattacharya, Debashish; Yoon, Hwan Su (2023). "Genome-wide signatures of adaptation to extreme environments in red algae". Nature Communications. 14 (1): 10. Bibcode:2023NatCo..14...10C. doi:10.1038/s41467-022-35566-x. PMC 9812998. PMID 36599855.

External links

• www.shigen.nig.ac.jp/algae_tree/CyanidiophyceaeE.html