Foreword
Nearly 150 years ago, naturalists like Darwin, Pfeffer, and Sachs were already
fascinated by plant gravity-sensing and gravity responses. At that time, they tried
to study these effects by modifying the gravity level and randomizing the gravity
vector with different methods and sophisticated tools like centrifuges and clinostats.
Only with the advent of (human) spaceflight some 70 years ago, however, plants
could be intensively investigated in different kinds of spacecrafts providing a freefall situation—a research environment without gravitational accelerations: capsules
falling in the vacuum of a drop tower, parabolic airplane flights, rockets, satellites,
and space stations in the low-Earth orbit—these are the exciting high-technology
workplaces and almost stimulus-free microgravity laboratory environments gravitational biologists use to clarify the impact of gravity on biological processes, cells,
and organisms. The diversity of ingenious sensing and response mechanisms that
obviously have evolved in parallel several times in the various kingdoms of life to
perceive the direction of gravity and to use this constant environmental cue for
orientation is the specific topic of the eight chapters of this latest booklet Gravitational Biology—Gravity Sensing and Graviorientation in Plants and Microorganisms in our series Springer Briefs on Space Life Sciences.
The first chapter provides a short introduction into the history of gravitational
biology research addressing the impact of gravity on the evolution of life on Earth,
general physical principles, and evolutionary as well as physiological aspects of
gravity-sensing and the specific gravity-related responses of motile microorganisms
(gravitaxis) and sessile algae, moss, ferns, and higher plants (gravitropism).
A comprehensive overview of the different microgravity-simulation methods
used on ground and real microgravity platforms, which are available for gravitational
biology research, is given in the second chapter. Centrifugation and microgravity
simulation are not only methods used for testing hardware and preparing rather
complex and rare experiments in microgravity—conducted with proper controls and
considering the specific side effects, they have become valuable and permanently
available tools also and not least for stand-alone experiments. With the completion
of the ISS, a low-Earth orbit platform for long-term microgravity studies and series
v
Nearly 150 years ago, naturalists like Darwin, Pfeffer, and Sachs were already
fascinated by plant gravity-sensing and gravity responses. At that time, they tried
to study these effects by modifying the gravity level and randomizing the gravity
vector with different methods and sophisticated tools like centrifuges and clinostats.
Only with the advent of (human) spaceflight some 70 years ago, however, plants
could be intensively investigated in different kinds of spacecrafts providing a freefall situation—a research environment without gravitational accelerations: capsules
falling in the vacuum of a drop tower, parabolic airplane flights, rockets, satellites,
and space stations in the low-Earth orbit—these are the exciting high-technology
workplaces and almost stimulus-free microgravity laboratory environments gravitational biologists use to clarify the impact of gravity on biological processes, cells,
and organisms. The diversity of ingenious sensing and response mechanisms that
obviously have evolved in parallel several times in the various kingdoms of life to
perceive the direction of gravity and to use this constant environmental cue for
orientation is the specific topic of the eight chapters of this latest booklet Gravitational Biology—Gravity Sensing and Graviorientation in Plants and Microorganisms in our series Springer Briefs on Space Life Sciences.
The first chapter provides a short introduction into the history of gravitational
biology research addressing the impact of gravity on the evolution of life on Earth,
general physical principles, and evolutionary as well as physiological aspects of
gravity-sensing and the specific gravity-related responses of motile microorganisms
(gravitaxis) and sessile algae, moss, ferns, and higher plants (gravitropism).
A comprehensive overview of the different microgravity-simulation methods
used on ground and real microgravity platforms, which are available for gravitational
biology research, is given in the second chapter. Centrifugation and microgravity
simulation are not only methods used for testing hardware and preparing rather
complex and rare experiments in microgravity—conducted with proper controls and
considering the specific side effects, they have become valuable and permanently
available tools also and not least for stand-alone experiments. With the completion
of the ISS, a low-Earth orbit platform for long-term microgravity studies and series
v