TY - JOUR
T1 - RNA interference of timeless gene does not disrupt circadian locomotor rhythms in the cricket Gryllus bimaculatus
AU - Danbara, Yoshiki
AU - Sakamoto, Tomoaki
AU - Uryu, Outa
AU - Tomioka, Kenji
N1 - Funding Information:
This study was supported in part by a grant from Japan Society for the Promotion of Science. We thank Dr. Akira Matsumoto for critical reading of the early version of the manuscript.
Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2010/12
Y1 - 2010/12
N2 - 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.
AB - 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.
KW - Circadian clock
KW - Clock gene
KW - Cricket
KW - Oscillatory mechanism
KW - Period
KW - RNAi
KW - Timeless
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U2 - 10.1016/j.jinsphys.2010.07.002
DO - 10.1016/j.jinsphys.2010.07.002
M3 - Article
C2 - 20637213
AN - SCOPUS:77958463575
SN - 0022-1910
VL - 56
SP - 1738
EP - 1745
JO - Journal of Insect Physiology
JF - Journal of Insect Physiology
IS - 12
ER -