title: Temperature cycle amplitude alters the adult eclosion time and expression pattern of the circadian clock gene period in the onion fly.
abstract: Soil temperature cycles are considered to play an important role in the entrainment of circadian clocks of underground insects. However, because of the low conductivity of soil, temperature cycles are gradually dampened and the phase of the temperature cycle is delayed with increasing soil depth. The onion fly, Delia antiqua, pupates at various soil depths, and its eclosion is timed by a circadian clock. This fly is able to compensate for the depth-dependent phase delay of temperature change by advancing the eclosion time with decreasing amplitude of the temperature cycle. Therefore, pupae can eclose at the appropriate time irrespective of their location at any depth. However, the mechanism that regulates eclosion time in response to temperature amplitude is still unknown. To understand whether this mechanism involves the circadian clock or further downstream physiological processes, we examined the expression patterns of period (per), a circadian clock gene, of D. antiqua under temperature cycles that were square wave cycles of 12-h warm phase (W) and 12-h cool phase (C) with the temperature difference of 8 °C (WC 29:21 °C) and 1 °C (WC 25.5:24.5 °C). The phase of oscillation in per expression was found to commence 3.5h earlier under WC 25.5:24.5 °C as compared to WC 29:21 °C. This difference was in close agreement with the eclosion time difference between the two temperature cycles, suggesting that the mechanism that responds to the temperature amplitude involves the circadian clock.
authors.affiliation: Faculty of Clinical Education, Ashiya University, Hyogo 659-8511, Japan. Electronic address: ymiyazaki@ashiya-u.ac.jp.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyazaki
authors.affiliation: Faculty of Clinical Education, Ashiya University, Hyogo 659-8511, Japan. Electronic address: ywatari@ashiya-u.ac.jp.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Watari
authors.affiliation: General Education Division, Miyagi Gakuin Women's University, Miyagi 981-8557, Japan. Electronic address: tanaka@mgu.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan. Electronic address: shingoto@sci.osaka-cu.ac.jp.
authors.forename: Shin G
authors.initials: SG
authors.lastname: Goto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D057906:Circadian Clocks; D004175:Diptera / Q000254:growth & development* / Q000378:metabolism; D015870:Gene Expression; D019476:Insect Proteins / Q000378:metabolism; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D056950:Period Circadian Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D019476:Insect Proteins; D056950:Period Circadian Proteins; D012269:Ribosomal Proteins
keywords: Circadian clock gene; Delia antiqua; Eclosion rhythm; Onion fly; Temperature cycle; period