experiment. Temperature was kept constant by a cooler. All systems worked flawlessly, but only 11 fish survived due to an insufficient oxygen concentration toward
the end of the experiment. Oreochromis mossambicus larvae produced significantly
larger utricular otoliths as compared to the 1-g controls (Anken et al. 2016). This
result confirmed earlier findings where Oreochromis larvae had been kept in a fast
rotating, submerged clinostat (Anken et al. 2010). Wall vessel rotation did not impair
the growth of cichlid otoliths (Brungs et al. 2011) but it increased the growth of
otoliths in zebrafish (Li et al. 2011, 2017a). This difference may be due to the
different behaviors of the two species: the cichlids are mouth-breading, whereas the
zebrafish lay eggs (Hilbig and Anken 2017).
A more illustrious community was flown in space for 4 weeks with an advanced
version of the aquatic OmegaHab system on the Russian Bion-M1 mission in spring
2013 (Hilbig and Anken 2017). OmegaHab was developed into an artificial miniature ecosystem consisting of three chambers (about 5 L): one chamber was home to
55 tilapia larvae (Oreochromis mossambicus), Mexican fresh water crustaceans
(Hyalella azteca), a few ram’s horn snails (Biomphalaria glabrata) and hornwort
(Ceratophyllum demersum), while a second photobioreactor chamber housed a
population of Euglena gracilis as primary oxygen producer. Between the chambers
a microbial filter populated by nitrifying bacteria that were to decompose the excreta
of the fish and transform them into fertilizer for the hornwort and the algae. This
closed life cycle mini-ecosystem worked well in microgravity 575 km above the
Earth until the LED lighting failed cutting off the “animal crew” from oxygen
resupply. While these species did not survive, Euglena continued to produce biomass by switching from photoautotrophic to heterotrophic mode, feeding on the
nutrients released by the decomposing organisms.
In cooperation with Chinese scientists an extremely miniaturized closed aquatic
ecosystem of 60 mL total volume was flown on the Shenzhou 8 spacecraft
containing Chlorella, Euglena and Bulnius in separate chambers (Li et al. 2017b).
One chamber housed the Euglena culture, while the other one Chlorella cells and
three snails. The spacecraft flew in orbit for 17.5 days and one snail survived. The
total cell numbers, the assimilation of nitrogen and phosphorous as well as concentrations of soluble proteins and carbohydrate decreased in the flight module as
compared to the ground module.
During the same mission Euglena cells were sent to space and fixed 40 min after
launch in microgravity with an RNA lysis buffer. In parallel, cells were fixed which
had been kept on a 1-g reference centrifuge (Nasir et al. 2014). After return of the
samples to ground the transcription of genes involved in signal transduction, oxidative stress defense, cell cycle regulation and heat shock responses was analyzed
using quantitative PCR. The analysis showed that Euglena suffers stress upon shortterm exposure to microgravity since of the 32 tested genes, 18 stress-induced genes,
involved in signal transduction, oxidative stress defense, cell cycle regulation and
heat shock responses, were up-regulated as indicated by quantitative PCR. These
results confirm that long-term space flights are valuable tools to study the behavior,
physiology and genetics of motile microorganisms which promise further insight
8.3 Aquacells and OmegaHab
117
the end of the experiment. Oreochromis mossambicus larvae produced significantly
larger utricular otoliths as compared to the 1-g controls (Anken et al. 2016). This
result confirmed earlier findings where Oreochromis larvae had been kept in a fast
rotating, submerged clinostat (Anken et al. 2010). Wall vessel rotation did not impair
the growth of cichlid otoliths (Brungs et al. 2011) but it increased the growth of
otoliths in zebrafish (Li et al. 2011, 2017a). This difference may be due to the
different behaviors of the two species: the cichlids are mouth-breading, whereas the
zebrafish lay eggs (Hilbig and Anken 2017).
A more illustrious community was flown in space for 4 weeks with an advanced
version of the aquatic OmegaHab system on the Russian Bion-M1 mission in spring
2013 (Hilbig and Anken 2017). OmegaHab was developed into an artificial miniature ecosystem consisting of three chambers (about 5 L): one chamber was home to
55 tilapia larvae (Oreochromis mossambicus), Mexican fresh water crustaceans
(Hyalella azteca), a few ram’s horn snails (Biomphalaria glabrata) and hornwort
(Ceratophyllum demersum), while a second photobioreactor chamber housed a
population of Euglena gracilis as primary oxygen producer. Between the chambers
a microbial filter populated by nitrifying bacteria that were to decompose the excreta
of the fish and transform them into fertilizer for the hornwort and the algae. This
closed life cycle mini-ecosystem worked well in microgravity 575 km above the
Earth until the LED lighting failed cutting off the “animal crew” from oxygen
resupply. While these species did not survive, Euglena continued to produce biomass by switching from photoautotrophic to heterotrophic mode, feeding on the
nutrients released by the decomposing organisms.
In cooperation with Chinese scientists an extremely miniaturized closed aquatic
ecosystem of 60 mL total volume was flown on the Shenzhou 8 spacecraft
containing Chlorella, Euglena and Bulnius in separate chambers (Li et al. 2017b).
One chamber housed the Euglena culture, while the other one Chlorella cells and
three snails. The spacecraft flew in orbit for 17.5 days and one snail survived. The
total cell numbers, the assimilation of nitrogen and phosphorous as well as concentrations of soluble proteins and carbohydrate decreased in the flight module as
compared to the ground module.
During the same mission Euglena cells were sent to space and fixed 40 min after
launch in microgravity with an RNA lysis buffer. In parallel, cells were fixed which
had been kept on a 1-g reference centrifuge (Nasir et al. 2014). After return of the
samples to ground the transcription of genes involved in signal transduction, oxidative stress defense, cell cycle regulation and heat shock responses was analyzed
using quantitative PCR. The analysis showed that Euglena suffers stress upon shortterm exposure to microgravity since of the 32 tested genes, 18 stress-induced genes,
involved in signal transduction, oxidative stress defense, cell cycle regulation and
heat shock responses, were up-regulated as indicated by quantitative PCR. These
results confirm that long-term space flights are valuable tools to study the behavior,
physiology and genetics of motile microorganisms which promise further insight
8.3 Aquacells and OmegaHab
117