Keystone Symposia 2008 Conference Schedule Sign up for PNAS Online eTocs
Link: Info for AuthorsLink: Editorial BoardLink: AboutLink: SubscribeLink: AdvertiseLink: ContactLink: Sitemap Link: PNAS Home
Proceedings of the National Academy of Sciences
Link: Current Issue "" Link: Archives "" Link: Online Submission ""  Link: Advanced Search

Published online on March 28, 2006, 10.1073/pnas.0600999103

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a colleague
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Tomitani, A.
Right arrow Articles by Ohno, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Tomitani, A.
Right arrow Articles by Ohno, T.
GeoRef
Right arrow GeoRef Citation
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg  
What's this?

Evolution
The evolutionary diversification of cyanobacteria: Molecular-phylogenetic and paleontological perspectives

( molecular evolution | phylogeny | Proterozoic )

Akiko Tomitani {dagger}{ddagger}, Andrew H. Knoll {sect}¶, Colleen M. Cavanaugh {sect}, and Terufumi Ohno {dagger}

{dagger}The Kyoto University Museum, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan; and {sect}Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138

Contributed by Andrew H. Knoll, February 6, 2006

Cyanobacteria have played a significant role in Earth history as primary producers and the ultimate source of atmospheric oxygen. To date, however, how and when the group diversified has remained unclear. Here, we combine molecular phylogenetic and paleontological studies to elucidate the pattern and timing of early cyanobacterial diversification. 16S rRNA, rbcL, and hetR genes were sequenced from 20 cyanobacterial strains distributed among 16 genera, with particular care taken to represent the known diversity of filamentous taxa. Unlike most other bacteria, some filamentous cyanobacteria evolved a degree of cell differentiation, producing both specialized cells for nitrogen fixation (heterocysts) and resting cells able to endure environmental stress (akinetes). Phylogenetic analyses support the hypothesis that cyanobacteria capable of cell differentiation are monophyletic, and the geological record provides both upper and lower bounds on the origin of this clade. Fossil akinetes have been identified in 1,650- to 1,400-mega-annum (Ma) cherts from Siberia, China, and Australia, and what may be the earliest known akinetes are preserved in {approx}2,100-Ma chert from West Africa. Geochemical evidence suggests that oxygen first reached levels that would compromise nitrogen fixation (and hence select for heterocyst differentiation) 2,450-2,320 Ma. Integrating phylogenetic analyses and geological data, we suggest that the clade of cyanobacteria marked by cell differentiation diverged once between 2,450 and 2,100 Ma, providing an internal bacterial calibration point for studies of molecular evolution in early organisms.

Author contributions: A.T., A.H.K., and C.M.C. performed research; A.T., C.M.C., and T.O. analyzed data; and A.T., A.H.K., and C.M.C. wrote the paper.

Conflict of interest statement: No conflicts declared.

{ddagger}To whom correspondence may be sent at the present address: Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan.

To whom correspondence may be addressed.

Akiko Tomitani, E-mail: tomitani{at}jamstec.go.jp
Andrew H. Knoll, E-mail: aKnoll{at}oeb.harvard.edu

www.pnas.org/cgi/doi/10.1073/pnas.0600999103
Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg    What's this?


This article has been cited by other articles in HighWire Press-hosted journals:


Home page
 Mol Biol EvolHome page
A.-L. Ducluzeau, S. Ouchane, and W. Nitschke
The cbb3 Oxidases Are an Ancient Innovation of the Domain Bacteria
Mol. Biol. Evol., June 1, 2008; 25(6): 1158 - 1166.
[Abstract] [Full Text] [PDF]

Home page
 Mol Biol EvolHome page
O. Deusch, G. Landan, M. Roettger, N. Gruenheit, K. V. Kowallik, J. F. Allen, W. Martin, and T. Dagan
Genes of Cyanobacterial Origin in Plant Nuclear Genomes Point to a Heterocyst-Forming Plastid Ancestor
Mol. Biol. Evol., April 1, 2008; 25(4): 748 - 761.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
S. Yamazaki, J. Nomata, and Y. Fujita
Differential Operation of Dual Protochlorophyllide Reductases for Chlorophyll Biosynthesis in Response to Environmental Oxygen Levels in the Cyanobacterium Leptolyngbya boryana
Plant Physiology, November 1, 2006; 142(3): 911 - 922.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
A. Y. Mulkidjanian, E. V. Koonin, K. S. Makarova, S. L. Mekhedov, A. Sorokin, Y. I. Wolf, A. Dufresne, F. Partensky, H. Burd, D. Kaznadzey, et al.
The cyanobacterial genome core and the origin of photosynthesis
PNAS, August 29, 2006; 103(35): 13126 - 13131.
[Abstract] [Full Text] [PDF]