Cellular responses of the ciliate, Tetrahymena thermophila, to far infrared irradiation.
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.
Shiurba
Robert
R
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
Hirabayashi
Tatsuo
T
Masuda
Masaru
M
Kawamura
Akinori
A
Komoike
Yuta
Y
Klitz
William
W
Kinowaki
Keiichi
K
Funatsu
Takashi
T
Kondo
Shunzo
S
Kiyokawa
Shin
S
Sugai
Toshiro
T
Kawamura
Kosuke
K
Namiki
Hideo
H
Higashinakagawa
Toru
T
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*
D006657:Histones; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan