field itself have to be considered, which had a strong impact on the alignment of
gravitactic organisms such a Euglena and Paramecium (Hemmersbach et al. 2014)
and mask the expected behavior known from experiments in real microgravity
(Häder et al. 1990; Hemmersbach-Krause et al. 1993) (cf. Chap. 3).
2.3 Centrifuges—The Benefit of Hypergravity
in Gravitational Biology Research
Centrifugation is an experimental approach to artificially and experimentally
increase the influence of gravitational acceleration greater than the one normally
acting on the surface of Earth (1 g). Hypergravity is a tool to obtain new insights into
gravity-related molecular and physiological mechanisms. Centrifugation experiments are widely used as controls to study the effects of launch, reentry and landing
accelerations of space vehicles like rocket payloads and reentry satellites, which
allows discriminating between these effects and the one of the microgravity conditions. Furthermore, the potential of hypergravity as a countermeasure method against
negative physiological adaption processes of the human body to long-term microgravity, such as a strong bone and muscle loss and decrease in cardiac functioning, is
under investigation.
In gravitational biology, different centrifuge designs are being used, operating at
low speed and thus physiological range up to 20 g, different to usual laboratory
centrifuges, where high accelerations are applied for separation during sample
preparation. Custom-built desktop centrifuges are appropriate to culture cells and
developing plants or (small) animals, while larger samples, increased hardware or
instruments for online analyses demand large centrifuges (for review see Frett et al.
2016). Centrifuges used in space provide an appropriate in-flight 1-g reference
control in close vicinity to the samples which are kept under microgravity. Consequently, experimental as well as control samples experience identical environmental
conditions such as vibration and radiation besides gravity, which facilitates the
identification of gravity-related responses. Centrifuges in space are also in use for
determination of thresholds of gravity-related processes. Examples are the STATEX
hardware including a centrifuge for the performance of an experiment addressing
the development of the vestibular system of toads and fish under microgravity
(Neubert et al. 1996). NIZEMI (Niedergeschwindigkeits-Zentrifugen-Mikroskop),
a slow rotating centrifuge microscope operated in space during the IML2 mission in
1994 and later on ground (Friedrich et al. 1996) clearly demonstrated the existence
of thresholds in plants and microorganisms in the range of 0.1–0.3 g.
1-g reference centrifuges and threshold centrifuges are also operated in the drop
tower or parabolic flights of airplanes and rockets (TEXUS, MAXUS) as well as in
the ESA’s European Modular Cultivation System EMCS and ESA’s BIOLAB, both
facilities aboard the ISS and designed to carry out experiments in biomedical
18
2 Methods for Gravitational Biology Research
gravitactic organisms such a Euglena and Paramecium (Hemmersbach et al. 2014)
and mask the expected behavior known from experiments in real microgravity
(Häder et al. 1990; Hemmersbach-Krause et al. 1993) (cf. Chap. 3).
2.3 Centrifuges—The Benefit of Hypergravity
in Gravitational Biology Research
Centrifugation is an experimental approach to artificially and experimentally
increase the influence of gravitational acceleration greater than the one normally
acting on the surface of Earth (1 g). Hypergravity is a tool to obtain new insights into
gravity-related molecular and physiological mechanisms. Centrifugation experiments are widely used as controls to study the effects of launch, reentry and landing
accelerations of space vehicles like rocket payloads and reentry satellites, which
allows discriminating between these effects and the one of the microgravity conditions. Furthermore, the potential of hypergravity as a countermeasure method against
negative physiological adaption processes of the human body to long-term microgravity, such as a strong bone and muscle loss and decrease in cardiac functioning, is
under investigation.
In gravitational biology, different centrifuge designs are being used, operating at
low speed and thus physiological range up to 20 g, different to usual laboratory
centrifuges, where high accelerations are applied for separation during sample
preparation. Custom-built desktop centrifuges are appropriate to culture cells and
developing plants or (small) animals, while larger samples, increased hardware or
instruments for online analyses demand large centrifuges (for review see Frett et al.
2016). Centrifuges used in space provide an appropriate in-flight 1-g reference
control in close vicinity to the samples which are kept under microgravity. Consequently, experimental as well as control samples experience identical environmental
conditions such as vibration and radiation besides gravity, which facilitates the
identification of gravity-related responses. Centrifuges in space are also in use for
determination of thresholds of gravity-related processes. Examples are the STATEX
hardware including a centrifuge for the performance of an experiment addressing
the development of the vestibular system of toads and fish under microgravity
(Neubert et al. 1996). NIZEMI (Niedergeschwindigkeits-Zentrifugen-Mikroskop),
a slow rotating centrifuge microscope operated in space during the IML2 mission in
1994 and later on ground (Friedrich et al. 1996) clearly demonstrated the existence
of thresholds in plants and microorganisms in the range of 0.1–0.3 g.
1-g reference centrifuges and threshold centrifuges are also operated in the drop
tower or parabolic flights of airplanes and rockets (TEXUS, MAXUS) as well as in
the ESA’s European Modular Cultivation System EMCS and ESA’s BIOLAB, both
facilities aboard the ISS and designed to carry out experiments in biomedical
18
2 Methods for Gravitational Biology Research