No description available.

No description available.

Thesis (M.S.)--Miami University, Dept. of Zoology, 2007. / Title from first page of PDF document. Includes bibliographical references (p. 17-20).

Virtually nothing is known about how internal circadian clocks interact with daily environmental cycles in nature. Previous work has shown that temperature and light are both able to successfully entrain (synchronize) circadian rhythms in eclosion (adult emergence) and locomotor activity in Sarcophaga crassipalpis when applied independently. However, much less work has been done to evaluate the relative strength of these Zeitgebers (time cues) when applied simultaneously. In nature, light and temperature cycles generally maintain a fixed relationship with one another, with peak soil and air temperature occurring about three hours after peak brightness each day. By manipulating the relationship between these Zeitgebers this project aims to evaluate the effects of conflicting environmental information on eclosion and locomotor activity rhythms in S. crassipalpis. We measured locomotor and eclosion activity under three temperature/light cycle regimes: 1) in-phase temperature and light cycles, with light and thermophase (warm-period) onset occurring simultaneously, 2) thermophase-delayed, beginning six hours after the onset of photoperiod (light-period), or 3) out-of-phase, with the beginning of photophase corresponding to the end of thermophase. In all experiments, eclosion times are very close to thermophase onset, while locomotor activity does not always hold the same phase position. In fact, in the out-of-phase experiment, locomotor activity is almost entirely synchronized with photophase while eclosion appears to anticipate thermophase onset. These findings suggest that eclosion and locomotor activity rhythms are controlled by different circadian oscillators. This fits with the ecological context of these vital life events. Timing of eclosion is critically important to wing development and the survival of the adult. This process is initiated after being underground, with minimal to no light input, for two weeks – therefore, the most reliable Zeitgeber would be daily soil temperature cycling. As these flies are diurnal, one could reasonably expect light to be the primary Zeitgeber for adult activity, as it is more consistent than temperature cycling. Overall, this implies that an organism’s life history and natural environment must be considered when investigating the circadian clock.

No description available.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references.

The purpose of this study was to begin a study characterizing the diapause state in Sarcophaga crassipalpis. Recent evidence suggests the diapause syndrome is a unique developmental state with its own set of genes expressed. Two cDNA libraries from the pupal brains of diapausing and nondiapausing S. crassipalpis were generated. These libraries will be the basis for future work determining the expressed and repressed genes during the diapause syndrome. The genetic regulation of diapause in S. crassipalpis is also of interest. This species enters diapause during metamorphosis, which is under regulation of the steroid hormone 20-hydroxyecdysone (20-HE). Because the metamorphic system is suspended for diapause in this species, whether or not the EcR is expressed in the diapause state is of interest. To address this issue, a partial EcR was cloned from S. crassipalpis by RT-PCR. This partial EcR was found in all developmental stages tested.

The objective of this study was to identify genes that are differentially regulated during diapause when compared with nondiapausing pupae in Sarcophaga crassipalpis. The results of a Suppression Subtractive Hybridization procedure was used to indentify genes that are differentially regulated in both diapause and nondiapausing states while suppressing genes that are common to both states. Randomly picked colonies from both subtractive libraries were isolated and the inserts sequenced. The sequences were analyzed using the bioinformatics tools NCBI, BlastX, Clustal W, etc. Out of 384 clones, 59 genes were found to be upregulated during diapause and 37 genes were found to be upregulated during a nondiapause pupal stage, no genes were found to be expressed commonly in both the diapause and nondiapause constructed libraries.

It is well known that 24-hour day-night (light-dark) cycles can entrain the circadian rhythms of most species possessing circadian clocks. However, much less is understood about how other environmental cycles operate as entraining signals (zeitgebers) to synchronize (entrain) the internal clock with the outside world. Potential non-photic zeitgebers include daily cycles of temperature, food availability, and social signals. This project’s goal is to evaluate the efficacy of temperature cycles of varying amplitudes, ranging from 1°C to 10°C, as potential zeitgebers for two different circadian rhythms, eclosion and locomotor activity, in the flesh fly (Sarcophaga crassipalpis). Both rhythms were monitored in individual flies, using infrared motion detectors, under precisely controlled 24-hour temperature cycles (12 hours of high temperature [thermophase] alternating with 12 hours of low temperature [cryophase]) in constant darkness. Our results show clear entrainment of eclosion, a once-in-a-lifetime event, and locomotor activity, reflecting daily sleep-wake rhythms, in response to temperature cycles at amplitudes of 2.5, 5, and 10o C. At 1o C amplitudes, the evidence indicates a partial effect of temperature on the phasing of the two behaviors but not true entrainment (phase regulation), suggesting that 1o C amplitudes may be near the threshold for detection by the entrainment pathways communicating with the circadian clock. Interestingly, although both light and temperature cycles entrain the locomotor activity rhythm, the entrainment profiles are remarkably different, thereby suggesting that light and temperature cycles activate different behavioral programs. Finally, flies placed under different constant temperatures have endogenous circadian periods of locomotor activity that are remarkably similar, indicating a high level of temperature compensation. Our results provide conclusive evidence that temperature is a strong circadian zeitgeber in flesh flies, thereby expanding the known repertoire of environmental cues these organisms use to sync their internal clock with the world around them. These findings also set the stage for future experiments designed to explore the interactions between light and temperature entrainment mechanisms – these zeitgeber interactions almost certainly occur in nature but have received little or no attention.

The diel locomotor activity patterns of wandering larvae in the flesh fly, Sarcophaga crassipalpis Macquart (Diptera: Sarcophagidae), were examined using a novel apparatus and shown to be primarily diurnal, but with a minority (37%) showing nocturnal activity. In response to the environmental stress of heat shock, a significantly larger proportion (72%) of the larvae became nocturnal. In comparison, adult circadian activity also was predominantly diurnal, but not correlated with the larval activity patterns. In addition, adult patterns showed age-related changes in entrainment and free running period. Finally, the phase of circadian-gated adult eclosion was shown to be entrained by a 3-day exposure to light-dark cycles delivered prior to pupariation, with the phase maintained throughout pupal-adult metamorphosis under constant dark conditions. These results demonstrate that environmental changes may have profound effects on the expression of 24-h activity patterns and circadian rhythms during different life stages throughout development.