Synchrony between Genetic Repressilators in Sister Cells in Different Temperatures

We used live E. coli containing synthetic genetic oscillators to study how the degree of synchrony between the genetic circuits of sister cells changes with temperature. We found that both the mean and the variability of the degree of synchrony between the fluorescence signals from sister cells are affected by temperature. Also, while most pairs of sister cells were found to be highly synchronous in each condition, the number of asynchronous pairs increased with increasing temperature, which was found to be due to disruptions in the oscillations. Finally we provide evidence that these disruptions tend to affect multiple generations as opposed to individual cells. These findings provide insight in how to design more robust synthetic circuits and in how cell division can affect their dynamics.

Authors:

• Jerome G. Chandraseelan
• Samuel M. D. Oliveira
• Antti Häkkinen
• Sofia Startceva
• Andre S. Ribeiro

Keywords:

• Repressilator
• robustness
• synchrony
• synthetic biology.

References:

[1] J. C. Dunlap, “Molecular bases for circadian clocks,” in Cell, vol. 96,
pp. 271-290, 1999.
[2] Z. Neubauer, and E. Calef, “Immunity phase-shift in defective lysogens:
Non-mutational hereditary change of early regulation of λ prophage,” in
J. Mol. Biol., vol. 51, pp. 1-13, 1970.
[3] R. E. Dolmetsch, K. Xu, R. S. Lewis, “Calcium oscillations increase the
efficiency and specificity of gene expression,” in Nature, vol. 392,
pp. 933-936, 1998.
[4] I. Mihalcescu, W. Hsing, and S. Leibler, “Resilient circadian oscillator
revealed in individual cyanobacteria,” in Nature, vol. 430, pp. 81-85,
2004.
[5] D. M. Virshup, and D. B. Forger, “Keeping the beat in the rising heat,”
in Cell, vol. 137, pp. 602-604, 2009.
[6] A. Ay, S. Knierer, A. Sperlea, J. Holland, and E. M. Ozbudak, “Short-
lived Her proteins drive robust synchronized oscillations in the zebrafish
segmentation clock,” in Development, vol. 140, pp. 3244-3253, 2013.
[7] M. B. Elowitz, and S. Leibler, “A synthetic oscillatory network of
transcriptional regulators,” in Nature, vol. 403, pp. 335-338, 2000.
[8] T. S. Gardner, C. R. Cantor, J. J. Collins, “Construction of a genetic
toggle switch in Escherichia coli,” in Nature, vol. 403, pp. 339-342,
2000.
[9] A. Becskei, and L. Serrano, “Engineering stability in gene networks by
autoregulation,” in Nature, vol. 405, pp. 590-593, 2000.
[10] N. Nandagopal, and M. B. Elowitz, “Synthetic biology: Integrated gene
circuits,” in Science, vol. 333, pp. 1244-1248, 2011.
[11] D. M. Wolf, and A. P.Arkin, "Motifs, modules and games in bacteria,"
in Curr. Opin. Microbiol., vol. 6, pp. 125-134, 2003.
[12] K. Kruse, and J. Julicher, ”Oscillations in cell biology,” in Curr. Opin.
Cell Biol., vol. 17, pp. 20-26, 2005.
[13] J. Stricker, S. Cookson, M. R. Bennett, W. H. Mather, et al., “A fast,
robust and tunable synthetic gene oscillator,” in Nature, vol. 456,
pp. 516-519, 2008.
[14] J. G. Chandraseelan, S. M. D. Oliveira, A. Hakkinen, H. Tran, et al.,
“Effects of temperature on the dynamics of the LacI-TetR-CI
repressilator,” in Mol. Biosyst., vol. 9, pp. 3117-3123, 2013.
[15] A. P. Dempster, N. M. Laird, and D. B. Rubin, “Maximum likelihood
from incomplete data via the EM algorithm,” in J. Royal Stat. Soc.
Ser. B (Methodological), vol. 39, pp. 1-38, 1977.