Circadian clock controlled gene expression in soybean seeds
ABSTRACT: Microarray expression profiling was used to identify genes expressed in developing soybean (Glycine max) seeds that are controlled by the circadian clock. Plants with developing seeds were entrained to 12hour light: 12 hour dark cycles and sampled in constant light conditions. Soybean seeds entrained to 12 hour-light:12 hour dark photocycles were harvested after 24 hours of constant light and temperature conditions. Timepoint 24h represents subjective dawn. To minimize developmental variation, flowers were marked as they opened and seeds were harvested from marked pods after 5 weeks. There are two replicate samples at each time point, and each sample consists of 8 seeds collected from three diffferent plants.
Project description:Microarray expression profiling was used to identify genes expressed in developing soybean (Glycine max) seeds that are controlled by the circadian clock. Plants with developing seeds were entrained to 12hour light: 12 hour dark cycles and sampled in constant light conditions. Overall design: Soybean seeds entrained to 12 hour-light:12 hour dark photocycles were harvested after 24 hours of constant light and temperature conditions. Timepoint 24h represents subjective dawn. To minimize developmental variation, flowers were marked as they opened and seeds were harvested from marked pods after 5 weeks. There are two replicate samples at each time point, and each sample consists of 8 seeds collected from three diffferent plants.
Project description:Setaria viridis (A10.1) circadian expression after light or temperature entrainment Overall design: Plants were grown under either 12 hour photocycles (12h light/12h dark) or 12 hour thermocycles (12h 32 deg C/ 12h 22 deg C) then sampled every 2 hours for 48 hours under constant light and constant temperature conditions (32 deg C). Photocycle entrained samples are labeled LDHH-F, and thermocycle entrained samples are entrained LLHC-F.
Project description:Mice lacking the CLOCK protein have a relatively subtle circadian phenotype, including a slightly shorter period in constant darkness, differences in phase resetting after 4-hour light pulses in the early and late night, and a variably advanced phase angle of entrainment in a light-dark (LD) cycle. The present series of experiments was conducted to more fully characterize the circadian phenotype of Clock(-/-) mice under various lighting conditions. A phase-response curve (PRC) to 4-hour light pulses in free-running mice was conducted; the results confirm that Clock(-/-) mice exhibit very large phase advances after 4-hour light pulses in the late subjective night but have relatively normal responses to light at other phases. The abnormal shape of the PRC to light may explain the tendency of CLOCK-deficient mice to begin activity before lights-out when housed in a 12-hour light:12-hour dark lighting schedule. To assess this relationship further, Clock(-/-) and wild-type control mice were entrained to skeleton lighting cycles (1L:23D and 1L:10D:1L:12D). Comparing entrainment under the 2 types of skeleton photoperiods revealed that exposure to 1-hour light in the morning leads to a phase advance of activity onset (expressed the following afternoon) in Clock(-/-) mice but not in the controls. Constant light typically causes an intensity-dependent increase in circadian period in mice, but this did not occur in CLOCK-deficient mice. The failure of Clock(-/-) mice to respond to the period-lengthening effect of constant light likely results from the increased functional impact of light falling in the phase advance zone of the PRC. Collectively, these experiments reveal that alterations in the response of CLOCK-deficient mice to light in several paradigms are likely due to an imbalance in the shape of the PRC to light.
Project description:The ability to change colour rapidly is widespread among ectotherms and has various functions including camouflage, communication and thermoregulation. The process of colour change can occur as an aperiodic event or be rhythmic, induced by cyclic environmental factors or regulated by internal oscillators. Despite the importance of colour change in reptile ecology, few studies have investigated the occurrence of a circadian rhythm in lizard pigmentation. Additionally, although colour change also entails changes in near-infrared reflectance, which may affect thermoregulation, little research has examined this part of the spectrum. We tested whether the bearded dragon lizard, Pogona vitticeps, displays an endogenous circadian rhythm in pigmentation changes that could be entrained by light/dark (LD) cycles and how light affected the relative change in reflectance in both ultraviolet-visible and near-infrared spectra. We subjected 11 lizards to four photoperiodic regimens: LD 12:12; LD 6:18; LD 18:6 and DD; and measured their dorsal skin reflectance at 3-hour intervals for 72 hours after a habituation period. A proportion of lizards displayed a significant rhythm under constant darkness, with maximum reflectance occurring in the subjective night. This endogenous rhythm synchronised to the different artificial LD cycles, with maximum reflectance occurring during dark phases, but did not vary in amplitude. In addition, the total ultraviolet-visible reflectance in relation to the total near-infrared reflectance was significantly higher during dark phases than during light phases. We conclude that P. vitticeps exhibits a circadian pigmentation rhythm of constant amplitude, regulated by internal oscillators and that can be entrained by light/dark cycles.
Project description:Analysis of urinary bladder in wild-type C57BL/6 females sacrificed every 4 hours at six time points under constant darkness after acclimation for 2 weeks under 12-hour light and 12-hour dark conditions. Results provide insight into circadian gene expression patterns in normal urinary bladder. Analysis of urinary bladder in wild-type C57BL/6 females sacrificed every 4 hours at six time points (n=2 for each time (CT 0, 4, 8, 12 and 20)) under constant darkness after acclimation for 2 weeks under 12-hour light and 12-hour dark conditions.
Project description:To explore daily rhythms of ocular gene expression in adult mice we performed the following experiments: i) Mice were entrained to a 12:12-hr light-dark (LD) cycle for 3 weeks. Then mice were transferred to constant darkness (DD) or remained in LD and eyes were collected at four-hour intervals over a three-day period; ii) Bmal1-/- mice and wild-type littermates were entrained to a 12:12-hr LD cycle for 3 weeks and eyes were collected at four-hour intervals over a one-day period in LD.
Project description:To gain insights into the mechanisms of TOC1 function in the Arabidopsis circadian clock we performed transcriptional profiling of Wild-Type (WT) and and TOC1 mutant plants (toc1-2) under constant light conditions for two days. Comparisons of WT and toc1-2. Two biological replicates each per array. Two Arabidopsis Oligonucleotide Microarrays (two-color Cy3 and Cy5). synchronized under 12-hour light:12-hour dark (LD) cycles for 10 days followed by two days under constant light conditions. Samples were collected at circadian time 16 (CT16).
Project description:After 2 week acclimation to 12 hr/12 hr light/dark regimen, C57/BL6 mice were subjected to a 36 hour period of constant darkness. Aortae were subsequently harvested at 4 hour intervals to 48 hours. Duplicate microarrays were hybridized with biotin-labeled probes derived from aorta tissue (6 pooled aortae/timepoint). Keywords = aorta, murine, circadian
Project description:Light has a strong effect on whole organism physiology, such as the circadian rhythms that are phase delayed and advanced by light given at early and late subjective night, respectively. Despite the importance of the phase-dependent light responses, little is known about the underlying molecular mechanism. We performed a comprehensive analysis of genes induced by light in a phase-dependent manner in the chicken pineal gland, an organ that represents a unique vertebrate clock system harboring intrinsic light sensitivity. Newborn chicks were entrained to 12-h light/12-h dark cycle for 7 days then transferred to constant darkness for a day to be exposed to light for 1 h from CT (circadian time) 6 (representing subjective day), CT14 (early subjective night) or CT22 (late subjective night). Control animals were kept in the dark without light pulse. The pineal glands were isolated at the end of the 1-h light pulse for gene expression analysis by Affymetrix GeneChip. Each condition contains 2 biological samples.
Project description:Poplar (Populus trichocarpa, clone Nisqually-1) plants were grown in a Conviron PGR 15 growth chamber using precise control of temperature, light, and humidity. Diurnal (driven) conditions included 12L:12D light cycles and 25C/12C thermocycles in three different combinations. These were: photocycles (LDHH), 12 hrs. light (L)/12 hrs. dark (D) at a constant temperature (25C; HH); photo/thermocycles (LDHC): 12 hrs. light (L) /12 hrs. dark (D) with a high day temperature (25C) and a low night temperature (12C); and thermocycles (LLHC): continuous light (LL) with 12 hrs. high/12 hrs. low temperature (25C, day; 12C, night). Light intensity and relative humidity were 700 micromol m-2s-2 and 50%, respectively. Three-month-old poplar plants were entrained for at least one week under the respective condition prior to initiation of each experiment. Leaves and stems from individual poplar plants were collected every four hours for 48 hrs in driven (diurnal) conditions followed by a two day freerun spacer under continuous light/temperature followed by two additional days of sampling under the same continuous free run condition.