RNA interference of timeless gene does not disrupt circadian locomotor rhythms in the cricket Gryllus bimaculatus

Yoshiki Danbara, Tomoaki Sakamoto, Outa Uryu, Kenji Tomioka

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Molecular studies revealed that autoregulatory negative feedback loops consisting of so-called " clock genes" constitute the circadian clock in Drosophila. However, this hypothesis is not fully supported in other insects and is thus to be examined. In the cricket Gryllus bimaculatus, we have previously shown that period (per) plays an essential role in the rhythm generation. In the present study, we cloned cDNA of the clock gene timeless (tim) and investigated its role in the cricket circadian oscillatory mechanism using RNA interference. Molecular structure of the cricket tim has rather high similarity to those of other insect species. Real-time RT-PCR analysis revealed that tim mRNA showed rhythmic expression in both LD and DD similar to that of per, peaking during the (subjective) night. When injected with tim double-stranded RNA (ds. tim), tim mRNA levels were significantly reduced and its circadian expression rhythm was eliminated. After the ds. tim treatment, however, adult crickets showed a clear locomotor rhythm in DD, with a free-running period significantly shorter than that of control crickets injected with Discosoma sp. Red2 (DsRed2) dsRNA. These results suggest that in the cricket, tim plays some role in fine-tuning of the free-running period but may not be essential for oscillation of the circadian clock.

Original languageEnglish
Pages (from-to)1738-1745
Number of pages8
JournalJournal of Insect Physiology
Volume56
Issue number12
DOIs
Publication statusPublished - Dec 1 2010

Keywords

  • Circadian clock
  • Clock gene
  • Cricket
  • Oscillatory mechanism
  • Period
  • RNAi
  • Timeless

ASJC Scopus subject areas

  • Physiology
  • Insect Science

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