Akemi Izumi-Kurotani

Motion sickness in amphibians.

We explored the question of whether amphibians get motion sickness by exposing anurans (frogs) and urodeles (salamanders) to the provocative stimulus of parabolic aircraft flight. Animals were fed before flight, and the presence of vomitus in their containers after flight was used to indicate motion-induced emesis. None of the species that we studied vomited during the 8 to 10 parabolas of each flight. However, at least one specimen from each of the anuran species Rana rugosa, Rana nigromaculata, Hyla japonica, and Rhacophorus schlegelii vomited in a period of 0.5 to 42 h after flight. Some specimens of R. nigromaculata, H. japonica, and R. schlegelii were also observed retching without emesis either during or shortly after exposure to parabolic flight. We were unable to induce either emesis or retching behavior in the aquatic from Xenopus laevis. Among the urodeles studied we saw no signs of motion sickness in either adult or larval Cynops pyrrhogaster, but at least one larval Hynobius nebulosus vomited shortly after parabolic flight. The amphibian species that exhibited the most motion sickness were the same ones that showed the greatest amount of tumbling during the microgravity phases of their parabolic flights. The most distinctive difference between motion sickness in amphibians and mammals that vomit, including man, is the long delay between a provocative stimulus and emesis proper in the amphibians. The retching behavior we induced in the frogs was identical to that described previously for frogs treated with emetic drugs. H. japonica, exposed to extended periods of microgravity on the MIR Space Station, flattened their bellies against the substrate and dorsiflexed their heads in a manner reminiscent of drug-induced nausea. In light of our current observations of retching behavior in motion sick H. japonica, we suggest that the previously observed behavior of three frogs on the MIR Space Station was a manifestation of motion sickness.

Behavior of Japanese tree frogs under microgravity on MIR and in parabolic flight.

Japanese tree frogs (Hyla japonica) were flown to the space station MIR and spent eight days in orbit during December, 1990. Under microgravity, their postures and behaviors were observed and recorded. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Frogs on a surface often bent their neck backward and walked backwards. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on land--a possible indicator of motion sickness. Observations on MIR were carried out twice to investigate the frogs adaptation to space. The frequency of failure in landing after a jump decreased in the second observation period. After the frogs returned to earth, readaptation processes were observed. The frogs behaved normally as early as 2.5 hours after landing.

Three‐dimensional recording and measurement of swimming paths of micro‐organisms with two synchronized monochrome cameras

Instrumentation is described that permits analysis of the three‐dimensional (3‐D) swimming paths of micro‐organisms. The signals from two monochrome cameras for the front and side views of micro‐organisms are encoded into a composite signal for a video tape recorder (VTR). The signals decoded from the VTR or those directly from the cameras are processed by computer.

Emesis and space motion sickness in amphibians.

Amphibians possess the ability to vomit in response to a variety of stimuli that provoke emesis in mammals. Pharmacological studies have establish that the ejection of gastric contents and the basic mechanism for vomiting have been phylogenetically conserved among these tetrapods. As part of on-going comparative studies on emesis in vertebrates, we previously documented that some postmetamorphic anurans and salamander larvae experience motion-induced emesis when exposed to the provocative stimulus of parabolic aircraft flight. However, more recent experiments suggest that there are strict conditions for inducing emesis in amphibians exposed to parabolic flight and that amphibians are not as sensitive to this stimulus as mammals. Further studies on emesis in lower vertebrates may help us understand the processes that cause emesis in abnormal gravitational regimes.

Astronewt: Early development of newt in space

AstroNewt experiment explores the effects of earth gravity on the early development of Japanese red-bellied newt, Cynops pyrrhogaster. Since female newts keep spermatophore in cloaca, fertilized eggs could be obtained without mating. Fertilization of newts egg occurs just prior to spawning, so that gonadotrophic cues applied to females in orbit leads to laying eggs fertilized just in space. A property of newt being kept in hibernation at low temperature may be of great help for the space experiment carried out with much limited resources. A general outline of the AstroNewt project is shown here in addition to some technical advances for the development of the project. Experimental schemes of two space experiments (IML-2 in summer 1994 and unmanned SFU at the beginning of 1995) are also shown.

Space experiment on behaviors of treefrog.

Japanese treefrogs (Hyla japonica) are planned to be sent to the space station MIR. Experimental system was developed to observe their behaviors under microgravity.

Chapter 8 Frog Experiment Onboard Space Station Mir

Publisher Summary This chapter discusses the frog experiment onboard space station Mir. Frogs sitting on a surface bent their neck backward sharply, did not fold their hind limbs completely, and pressed their abdomen against the substrate. They walked backwards in this posture. This typical posture resembles that adopted during the emetic behavior process on the ground, although the posture in space lasts much longer. The possible mechanism of induction of this unique posture in orbit is discussed in the chapter. Frogs in this posture are considered to be in an emetic state, possibly due to motion sickness. Response behavior to some external stimuli was observed in orbit. Body color change in response to the background color appeared to be delayed or slowed down. Response behavior to other stimuli showed little change as long as the animal maintained contact with a substrate. Once it left the surface, the floating frog could not control its movements to provide coordinated motility for locomotion and orientation.

FRog In Space (FRIS) Experiment on MIR

Japanese tree frogs (Hyla japonica ) were sent to the MIR station and spent eight days in orbit in December, 1990. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Some frogs showed tumbling. On a surface of something, more than half of frogs bent their neck backward, pressed their abdomens against the substrate with relaxation of their hindlimbs, and walked backward. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on ground. The frequency of failure to land after a jump decreased in the later observation period. This result suggests that frogs could adapt to microgravity. Behaviors ofthe flight frogs became normal as early as 2.5 hours after landing.