Unveiling a rhythmic regulatory mode hidden in developmental tissue growth by fluorescence live imaging-based mathematical modeling  Tadahiro Iimura, Ji-Won Lee  Journal of Oral Biosciences  Volume 59, Issue 1, Pages 6-11 (February 2017) DOI: 10.1016/j.job.2016.09.001 Copyright © 2016 Japanese Association for Oral Biology Terms and Conditions

Fig. 1 Bistable model of the G1/S transition. The RB-E2F pathway and related multiple positive feedback loops can generate bistability, in which a single cell in the G1 phase can enter into either the G1 phase or S phase under intrinsic and extrinsic stimuli. This model thoroughly demonstrates that the stochastic cellular behavior of the G1/S transition and varying pace of cell cycle progression in distinct cells are the likely causes of fluctuations in cellular response and behavior in multicellular tissues. Journal of Oral Biosciences 2017 59, 6-11DOI: (10.1016/j.job.2016.09.001) Copyright © 2016 Japanese Association for Oral Biology Terms and Conditions

Fig. 2 Progressive mode of the stochastic G1/S transition that drives embryonic body elongation in notochordal cells (see [1] for detailed description). (A) Fucci (fluorescent ubiquitination-based cell cycle indicator) labels cell nuclei in the G1 phase and S/G2/M phase in red and green, respectively; it consists of two distinct chimeric proteins (mKO2-zCdt1 and mAG-zGeminin) that reciprocally accumulate in the G1 and S/G2/M phases. (B) Cecyil (cell cycle illuminated: a zebrafish line producing zFucci) embryos at the 17 somite stage. The anterior is to the left, the posterior is to the right. (C) A mid-sagittal optical section of a fixed Cecyil embryo at 22 hpf counterstained with phalloidin Alexa Fluor 647. (D, E) Mid-sagittal optical section of a fixed Cecyil embryo at 18 hpf. (D) DIC (differential interference contrast) and (E) fluorescence images. (F–K) Mid-sagittal optical sections of a developing Cecyil embryo. (F–H) DIC images obtained at three different time points and (I–K) their corresponding fluorescence images. (L) Embryonic stages are indicated by somite stages (s.s.). Temporal changes in the red and green fluorescence intensities of the cell (indicated by the white arrow in G–H) are plotted. The crossing time point of the red and green lines (115min, in 18 somite stages) is selected as the time at which the G1/S transition occurred. White scale bars: 100 mm. Anterior to the left, posterior to the right. Dorsal to the top, ventral to the bottom. Adapted from [1] Sugiyama M, Saitou T, Kurokawa H, Sakaue-Sawano A, Imamura T, Miyawaki A, Iimura T. Live imaging-based model selection reveals periodic regulation of the stochastic G1/S phase transition in vertebrate axial development. PLoS Comput Biol 2014;10:e1003957. doi:10.1371/journal.pcbi.1003957. http://journals.plos.org/ploscompbiol/article?id=info:doi/10.1371/journal.pcbi.1003957. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) Journal of Oral Biosciences 2017 59, 6-11DOI: (10.1016/j.job.2016.09.001) Copyright © 2016 Japanese Association for Oral Biology Terms and Conditions

Fig. 3 Schematic summary of the live imaging-based mathematical modeling. This methodological approach consists of three successive processes: (A) Quantitative data acquisition from fluorescence live imaging, (B) mathematical model establishment, and (C) model selection. Each process is further divided into sub-processes, as shown in each box. Journal of Oral Biosciences 2017 59, 6-11DOI: (10.1016/j.job.2016.09.001) Copyright © 2016 Japanese Association for Oral Biology Terms and Conditions