Early candidacy for differentiation into heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120
- PDF / 441,231 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 33 Downloads / 195 Views
ORIGINAL PAPER
Early candidacy for differentiation into heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120 Masakazu Toyoshima • Naobumi V. Sasaki Makoto Fujiwara • Shigeki Ehira • Masayuki Ohmori • Naoki Sato
•
Received: 8 June 2009 / Revised: 15 October 2009 / Accepted: 26 October 2009 / Published online: 13 November 2009 Ó Springer-Verlag 2009
Abstract The filamentous cyanobacterium Anabaena sp. PCC 7120 fixes dinitrogen facultatively. Upon depletion of combined nitrogen, about 10% of vegetative cells within the filaments differentiate terminally into nitrogen-fixing cells. The heterocyst has been studied as a model system of prokaryotic cell differentiation, with major focus on signal transduction and pattern formation. The fate of heterocyst differentiation is determined at about the eighth hour of induction (point of no return), well before conspicuous morphological or metabolic changes occur. However, little is known about how the initial heterocysts are selected after the induction by nitrogen deprivation. To address this question, we followed the fate of every cells on agar plates after nitrogen deprivation with an interval of 4 h. About 10% of heterocysts were formed without prior division after the start of nitrogen deprivation. The intensity of fluorescence of GFP in the transformants of hetR-gfp increased markedly in the future heterocysts at the fourth hour with respect to other cells. We also noted that the growing filaments consisted of clusters of four consecutive
cells that we call quartets. About 75% of initial heterocysts originated from either of the two outer cells of quartets at the start of nitrogen deprivation. These results suggest that the future heterocysts are loosely selected at early times after the start of nitrogen deprivation, before the commitment. Such early candidacy could be explained by different properties of the outer and inner cells of a quartet, but the molecular nature of candidacy remains to be uncovered. Keywords Filamentous cyanobacteria Anabaena sp. PCC 7120 Heterocyst candidacy Differentiation Cell lineage Cell division Pattern formation Frequently iterated observation Spatial periodicity Quartet Abbreviations GFP Green fluorescent protein HLDS Heterocyst lineage description system MEM Maximum entropy method
Communicated by Erko Stackebrandt.
Electronic supplementary material The online version of this article (doi:10.1007/s00203-009-0525-4) contains supplementary material, which is available to authorized users. M. Toyoshima N. V. Sasaki M. Fujiwara N. Sato (&) Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan e-mail: [email protected] S. Ehira M. Ohmori Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
Introduction Upon depletion of combined nitrogen, Anabaena sp. PCC 7120 (sometimes referred to as Nostoc sp. PCC 7120; hereinafter denoted
Data Loading...
