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Pigment Dispersing Factor: An Output Regulator of the Circadian Clock in the German CockroachDepartment of Entomology, National Taiwan University, Taipei, Taiwan, Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
Department of Entomology, National Taiwan University, Taipei, Taiwan, m480{at}ntu.edu.tw Pigment-dispersing factor (PDF) is a neuropeptide that is synthesized specifically and constantly in the circadian clock cells of many insects. The functions of PDF have not been fully determined, but it might serve as the output and coupling signal of circadian locomotor rhythms. In this experiment, we explore the functions of PDF in the German cockroach with RNA interference technique. Since the 2nd day after pdf double-strand RNA (dsRNA) injection, the amount of pdf mRNA decreased significantly, and this knockdown effect could persist at least 56 days. With immunostaining technique, the clock cells of pdf dsRNA-injected cockroaches could not be stained by anti-PDF antibody. In the behavioral study, pdf dsRNA injection caused rhythmic males to become arrhythmic in light-dark cycles or in constant darkness. In addition, due to the nocturnal nature of the German cockroaches, the locomotor activity increased after lights-off or entering subjective night. However, this activity peak gradually disappeared after pdf dsRNA injection. Based on these 2 lines of evidences, PDF serves as an output regulator of locomotor circadian rhythm in the German cockroach.
Key Words: locomotion circadian rhythm neuropeptides RNA interference gene silencing Blattella germanica
Journal of Biological Rhythms, Vol. 24, No. 1,
35-43 (2009) |
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