Before transfer to light with an incident intensity of 61 µE m
−2 s
−1, dark-arrested cultures in small flasks were covered with colour filters (Lee Filters, UK): Blood Red (#789), Marius Red (#787), Primary Green (#139), Moonlight Blue (#183) and Special Medium Blue (#363). For the flow cytometry and qPCR experiments, a reduced set of filters was used, consisting of Blood Red, Primary Green and Special Medium Blue (Table
1). The transmittance spectrum of each filter (Supplementary Fig.
S2) was measured using a Lambda-650S spectrophotometer equipped with an
integrating sphere (PerkinElmer). To reduce the potential confounding effect of light intensity on the spectral composition experiments, an approximate correction was made to compensate for the transmittance in the spectral range of each colour filter. The objective was to provide approximately the same incident light intensity, in the wavelength range of the colour filter, for the colour filter treatment versus the control receiving the full spectrum (Supplementary Fig.
S3). The approximate correction was made by changing the illumination to compensate for the transmittance at the wavelength of maximum transmittance of each colour filter. Dark and light controls were included by covering flasks with aluminum foil or leaving them uncovered. All experiments were carried out in triplicate.
Bilcke G., Van Craenenbroeck L., Castagna A., Osuna-Cruz C.M., Vandepoele K., Sabbe K., De Veylder L, & Vyverman W. (2021). Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta. Scientific Reports, 11, 17560.