[
International Worm Meeting,
2007]
C. elegans is one of the best studied model laboratory organisms in the word. Somewhat ironically, it is also among the least understood animals in its native environment. Despite the fact that C. elegans and related nematodes are wide spread in nature, nobody has been able to visualize them in their natural context. If a method were available to easily visualize nematodes in three dimensions, much could be learned about the worms ecology. Phenomena such as aerotaxis, chemical communication, aggregation behavior, choice of food, and avoidance of noxious material could be studied in a realistic and controlled environment with a suitable 3D imaging technique. Magnetic Resonance Imaging (MRI) has the potential for 3D worm imaging in decaying organic matter. In a magnetic field, chemical nuclei with a net spin will behave like tiny bar magnets and align with the magnetic field according to the Boltzmann equation. The tiny bar magnets in the external magnetic field behave like a gyroscope in the earths gravitational field, and the precession of chemical nuclei can be detected as an oscillating electrical signal. MRI detects the signal from water and spatially encodes the position of water molecules in the sample by the application of magnetic field gradients in three dimensions. We are investigating different ways of using MRI to image worms moving in simple substrates. We have utilized 4 different magnetic fields—4.7 T, 11.1 T, 14.1 T, and 17.6 T—at the University of Florida Advanced Magnetic Resonance Imaging and Spectroscopy (AMRIS) facility and the National High Magnetic Field Laboratory (NHMLF). Each different system has advantages and disadvantages and different sample size requirements. The major issue to contend with is the trade-off between resolution, dynamics of moving worms, and signal-to-noise. High-resolution datasets (~10-50 microns) are possible with fixed samples and long measurement times (hours). However, in order to be able to monitor the movement of worms, the resolution needs to be decreased in order to capture worm movement. Progress in all of these areas will be presented. Support: Human Frontier Science Program (ASE & MdB).
[
International Worm Meeting,
2005]
As exposures to the space environment become longer, information regarding the effects on biological aging will become important. We have not yet fully clarified aging processes in space environments. The aging process and lifespan are affected by various kinds of environmental factors including oxygen concentration (1), temperature and radiation. The aging phenomena that we usually see occur under certain conditions on the ground. Space environments differ from ground environments especially with regard to the radiation spectrum and gravity. We participated in the International C. elegans Experiment(ICE)First that examined the effects of a 10-day space flight on the nematode C. elegans. C. elegans has frequently been used for study of aging because of its short lifespan. Recently, Morley et al. reported that Huntington's-like polyglutamine (polyQ)-repeat proteins expressed in the muscle of C. elegans form aggregates as the animals age, and that this aggregation is delayed in long-lived mutants(2). We measured the polyQ aggregates in these nematodes after space flight as an aging marker. Herndon et al. showed that the sarcomere orientation in the body-wall muscle becomes disorderly as the animals age(3). We also observed the sarcomere orientation in the body-wall muscle of these nematodes after space flight as another aging marker. Acknowledgement: We thank Dr. R. L. Morimoto (Northwestern University) for providing us polyQ-YFP C. elegans strains. We also thank CGC for other strains. ICE-First was mainly conducted by the French Space Agency (CNES), with support of the European Space Agency and the Space Research Organization of the Netherlands. We are grateful to Dr. Michel Viso (CNES), Dr. K. Kuriyama (JAXA) and Dr. A. Higashitani (Tohoku University) for their support and suggestion for our experiment. References: 1) Honda S., Ishii N, Suzuki K, Matsuo M. J Gerontol. 48:B57-61. 1993 2) James F. Morley, Heather R. Brignull, Jill J. Weyers, and Richard I. Morimoto. Proc. Natl. Acad. Sci. USA, 99: 10417-10422. 2002 3) Herndon LA, Schmeissner PJ, Dudaronek JM, Brown PA, Listner KM, Sakano Y, Paupard MC, Hall DH, Driscoll M. Nature. 419:808-814. 2002