Effects of Microgravity-Induced Weightlessness on
Aurelia Ephyra Differentiation and Statolith Synthesis
Science Discipline
Developmental biology
Investigator |
Institute |
Dorothy B. Spangenberg |
Eastern Virginia Medical School |
|
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Co-Investigators |
Institute |
None |
Research Subjects
Aurelia aurita (jellyfish)
Flight: 2478
Ground Based Controls
Synchronous, Delayed synchronous
Key Flight Hardware
Ambient Temperature Recorder, Jellyfish Kit and Kit Containers, Olympus 802 Camcorder, Refrigerator/Incubator Module
Objectives/Hypothesis
Aurelia polyps and ephyrae were exposed to microgravity for 9 days as part of the SLS-1 mission. This experiment was to study the effects of microgravity on: the development of ephyrae from polyps; the development of the graviceptors (rhopalia) of ephyrae; the formation or demineralization of statoliths of rhopalia; and the swimming/pulsing behavior of ephyrae.
Approach or Method
Polyps were induced to strobilate at 28 °C, using iodine or thyroxine, at 48 (L-48h) and 24 (L-24h) hours before launch, and 8 hours after lift-off (L+8h). Some ephyrae that formed in space were fixed in space on mission day 8, while others were fixed postflight. Postflight, light, and electron scanning microscope examinations were performed.
Results
The number of ephyrae formed per polyp were slightly higher in the L+8h groups as compared to those induced at L-24h and L-48h. On Earth, iodine is used by jellyfish to synthesize jellyfish-thyroxine (Jf-T4), which is necessary for ephyra production. Since iodine-treated polyps gave rise to ephyrae in space, it appears that jellyfish are able to synthesize Jf-T4 in space. The two groups of polyps not given the inducer still formed ephyrae in space, presumably due to enhanced Jf-T4 synthesis, utilization, or accumulation. Morphologically, ephyrae that developed in space were very similar to those that developed on Earth. Quantitation of arm numbers revealed that there were no significant differences between space and Earth-developed ephyrae. Pulsing abnormalities, however, were found in greater numbers (18.3%) than in Earth-developed controls (2.9%). These abnormalities suggest abnormal development of the graviceptors, the neuromuscular system, or a defect in the integration between systems in these microgravity-sensitive animals.
Publications
Spangenberg, D. et al.: Haircell and Statocyst Differentiation in Aurelia Ephyrae Which Developed in Microgravity (abstract). American Society for Gravitational and Space Biology Bulletin, vol. 10(1), Oct 1996, p. 34.
Spangenberg, D. and F. Lattanzio: Computer-Assisted Videoanalysis of Pulsing/Swimming Behavior of Aurelia Ephyrae from the SLS-1 Mission. American Society for Gravitational and Space Biology Bulletin, vol. 8(1), Oct 1994, p. 48.
Spangenberg, D.B.: Rhopalium Development in Aurelia aurita Ephyrae. Hydrobiologia, vol. 216–217, June 28, 1991, pp. 45–49.†
Spangenberg, D.B.: Effects of Microgravity on Jellyfish Development and Behavior (abstract). American Society for Gravitational and Space Biology Bulletin, vol. 6(1), Oct 1992, p. 100.
Spangenberg, D.B. et al.: Development Studies of Aurelia (Jellyfish) Ephyrae Which Developed during the SLS-1 Mission. Advances in Space Research, vol. 14(8), 1994, pp. 239–247.
Spangenberg, D.B. et al.: Graviceptor Development in Jellyfish Ephyrae in Space and on Earth. Advances in Space Research, vol. 14(8), 1994, pp. 317–325.
Spangenberg, D.B. et al.: Effects of Weightlessness on Aurelia Budding and Ephyra Development. American Society for Gravitational and Space Biology Bulletin, vol. 9, 1995, p. 88.