title: Cellular responses of the ciliate, Tetrahymena thermophila, to far infrared irradiation.
abstract: Infrared rays from sunlight permeate the earth's atmosphere, yet little is known about their interactions with living organisms. To learn whether they affect cell structure and function, we tested the ciliated protozoan, Tetrahymena thermophila. These unicellular eukaryotes aggregate in swarms near the surface of freshwater habitats, where direct and diffuse solar radiation impinge upon the water-air interface. We report that populations irradiated in laboratory cultures grew and mated normally, but major changes occurred in cell physiology during the stationary phase. Early on, there were significant reductions in chromatin body size and the antibody reactivity of methyl groups on lysine residues 4 and 9 in histone H3. Later, when cells began to starve, messenger RNAs for key proteins related to chromatin structure, intermediary metabolism and cellular motility increased from two- to nearly nine-fold. Metabolic activity, swimming speed and linearity of motion also increased, and spindle shaped cells with a caudal cilium appeared. Our findings suggest that infrared radiation enhances differentiation towards a dispersal cell-like phenotype in saturated populations of Tetrahymena thermophila.
authors.affiliation: Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. shiurba@waseda.jp
authors.forename: Robert
authors.initials: R
authors.lastname: Shiurba
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Hirabayashi
authors.forename: Masaru
authors.initials: M
authors.lastname: Masuda
authors.forename: Akinori
authors.initials: A
authors.lastname: Kawamura
authors.forename: Yuta
authors.initials: Y
authors.lastname: Komoike
authors.forename: William
authors.initials: W
authors.lastname: Klitz
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kinowaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Funatsu
authors.forename: Shunzo
authors.initials: S
authors.lastname: Kondo
authors.forename: Shin
authors.initials: S
authors.lastname: Kiyokawa
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sugai
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kawamura
authors.forename: Hideo
authors.initials: H
authors.lastname: Namiki
authors.forename: Toru
authors.initials: T
authors.lastname: Higashinakagawa
mesh_terms: D000818:Animals; D015870:Gene Expression / Q000528:radiation effects; D006657:Histones / Q000378:metabolism; D007259:Infrared Rays; D008745:Methylation; D008854:Microscopy, Electron; D018462:Photobiology; D015800:Protozoan Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D016808:Tetrahymena thermophila / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D006657:Histones; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan