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Development of gravity-sensing organs in altered gravityExperiments are described in which the development of the gravity-sensing organs was studied in newt larvae reared in microgravity on the IML-2 mission and in Aplysia embryos and larvae reared on a centrifuge at 1 to 5 g. In Aplysia embryos, the statolith (single dense mass on which gravity and linear acceleration act) was reduced in size in a graded fashion at increasing g. In early post-metamorphic Aplysia or even in isolated statocysts from such animals, the number of statoconia produced is reduced at high g. Newt larvae launched before any of the otoconia were formed and reared for 15 days in microgravity had nearly adult labyrinths at the end of the IML-2 mission. The otoliths of the saccule and utricle were the same size in flight and ground-reared larvae. However, the system of aragonitic otoconia produced in the endolymphatic sac in amphibians was much larger and developed earlier in the flight-reared larvae. At later developmental stages, the aragonitic otoconia enter and fill the saccule. One flight-reared larva was maintained for nine months post-flight and the size of the saccular otolith, as well as the volume of otoconia within the endolymphatic sac, were considerably larger than in age-matched, ground-reared newts. This suggests that rearing in microgravity initiates a process that continues for several months after introduction to 1-g, which greatly increases the volume of otoconia. The flight-reared animal had abnormal posture, pointing its head upward, whereas normal ground-reared newts always keep their head horizontal. This suggests that rearing for even a short period in microgravity can have lasting functional consequences in an animal subsequently reared in 1-g conditions on Earth.
Document ID
20040089478
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Wiederhold, M. L.
(University of Texas Health Science Center San Antonio 78284-7777, United States)
Gao, W. Y.
Harrison, J. L.
Hejl, R.
Date Acquired
August 21, 2013
Publication Date
June 1, 1997
Publication Information
Publication: Gravitational and space biology bulletin : publication of the American Society for Gravitational and Space Biology
Volume: 10
Issue: 2
ISSN: 1089-988X
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: NAG2-730
CONTRACT_GRANT: NAG2-952
Distribution Limits
Public
Copyright
Other
Keywords
STS-65 Shuttle Project
Flight Experiment
short duration
Non-NASA Center
manned
NASA Discipline Neuroscience

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