Frederick J. Tan, Arend Sidow, Thaisan Tonthat, Heather L. McCullough, Anton Valouev, Kathy Zeng, Heather Peckham, Gina Costa, Andrew Fire, Daniel P. Riordan, Steven M. Johnson, Joel Malek, Jeremy Stuart, Kevin McKernan, Jeffrey Ichikawa, Swati Ranade
[
International Worm Meeting,
2007]
We are working toward a detailed structural and dynamic picture of C. elegans chromatin. Nucleosome positions within the chromatin landscape are known to serve as a major determinant of DNA accessibility to transcription factors and other interacting components. To delineate nucleosomal patterns in C. elegans, we are carrying out a genome-wide analysis in which DNA fragments corresponding to nucleosome cores are liberated using Micrococcal nuclease. Sequence analysis of an initial set of putative nucleosome cores obtained in this manner from a mixed-stage population of C. elegans reveals a combined picture of flexibility and constraint in nucleosome positioning. As had previously been observed in studies of individual loci in diverse biological systems, we observe areas in the genome where nucleosomes can adopt a wide variety of positions in a given region, areas with little or no nucleosome coverage, and areas where nucleosomes reproducibly adopt a specific positional pattern. In addition to illuminating numerous aspects of chromatin structure for C. elegans, this analysis provides a reference from which to begin an investigation of relationships between the nucleosomal pattern, chromosomal architecture, and lineage-based gene activity on a genome-wide scale. We are currently extending this analysis using ultra-high-throughput sequencing techniques analyzing the genomic positions of millions of nucleosome cores toward the end of producing a high-resolution nucleosome position map of the C. elegans genome.
[
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