Cycling extracts can be supplemented with green fluorescent protein with a nuclear localization signal (GFP-NLS) and demembranated sperm nuclei which we image with a confocal microscope. Under these conditions biochemical oscillations persist and drive the spontaneous formation of nuclei in the extract. Such cell cycle oscillations can be observed by the fluorescent nuclei (importing GFP-NLS) that periodically appear (interphase) and disappear (mitotic phase). (from Nolet et al (2020))

Creating artificial cells and time lapse imaging

We use time-lapse microscopy to image frog egg extract and the frog and fish embryo development.
In vitro, we encapsulate the egg extract in droplets of different sizes using water-in-oil microemulsions. Those egg extract droplets, also known as artificial cells, perform several robust cell cycles. The egg extract is supplemented with various fluorescent reporters to visualize these periodic cell cycle processes. Using an epifluorescence microscope, we follow the behavior of some proteins and self-organized subcellular structures in bright-field and multiple fluorescence channels in time-lapse. 
In vivo, we image the early embryonic development of African clawed frog, killifish, and zebrafish embryos using a fluorescence stereo zoom microscope. Using fluorescent reporters, we follow and characterize the cellular and subcellular structures of the organisms during the first stages of development.

Temperature control

Many biological/biochemical processes such as the early embryonic development of African clawed frog, killifish, and zebrafish embryos are largely influenced by the environment, such as their surrounding temperature. In order to study this aspect we develop customized temperature devices that allow to precisely control temperature gradients, either locally within the embryo to desynchronize cell division timing, or over multiple embryos to compare the temperature-dependent developmental differences. To this end, we specifically design devices using Peltier elements as heaters and/or coolers in which the embryos can be deposited and studied using microscopy (see e.g. the figure).
Custom-made device used to induce a desynchronization in cell division timing within an embryo induced by a temperature gradient (Anderson et al (2017)).


Microfluidics involves the manipulation and control of minute fluid volumes, typically on the microliter or nanoliter scale. We design and use droplet-based microfluidic devices to accurately control the dimensions and content of artificial cells (droplets of egg extract). This approach also leads to higher throughput and reproducibility of our experiments. 

Selected publications


Puls*, O.; Ruiz-Reynés*, D.; Tavella, F.; Jin, M.; Kim, Y.; Gelens*, L.; Yang*, Q.

Mitotic waves in frog egg extracts: Transition from phase waves to trigger waves

2024, visited: 23.01.2024.

Links | BibTeX


Nolet, F. E. *; Vandervelde, A. *; Vanderbeke, A. *; Pineros, L. *; Chang, J. B.; Gelens, L.

Nuclei determine the spatial origin of mitotic waves

In: eLife, vol. 9, pp. e52868, 2020, ISSN: 2050-084X.

Links | BibTeX


Rombouts, J.; Vandervelde, A.; Gelens, L.

Delay models for the early embryonic cell cycle oscillator

In: PLoS One, vol. 13, no. 3, pp. 1-21, 2018.

Links | BibTeX


Anderson*, G. A.; Gelens*, L.; Baker, J.; Ferrell, J. E. Jr.

Desynchronizing Embryonic Cell Division Waves Reveals the Robustness of Xenopus laevis Development

In: Cell Reports, vol. 21, iss. 1, pp. 37–46, 2017, (featured on the cover).

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Gelens, L.; Huang, K. C.; Jr., J. E. Ferrell

How does the Xenopus laevis embryonic cell cycle avoid spatial chaos?

In: Cell Reports, vol. 12, no. 5, pp. 892–900, 2015, ISSN: 2211-1247.

Abstract | Links | BibTeX