A daily temporal program for rhythmic expression of protein-coding and non-coding genes in response to light and dark in Synechocystis sp. PCC 6803
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ABSTRACT:
ORGANISM(S): Synechocystis sp. PCC 6803
PROVIDER: GSE47482 | GEO | 2013/05/30
SECONDARY ACCESSION(S): PRJNA205863
REPOSITORIES: GEO
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Project description:We investigated Synechocystis high-density microarray data of three high-resolution time-series experiments with alternating light/dark rhythm, transition to continuous light, and transition to continuous darkness. Using M-bM-^@M-^Xleast oscillating setM-bM-^@M-^Y normalization and a clustering approach we found a daily temporal program for rhythmic expression of protein-coding and non-coding genes under light/dark conditions. All rhythms, however, damped out rapidly under continuous conditions. We quantified gene expression of wild type Synechocystis PCC 6083 over 48 hours under three different light regimes; 12:12-h light/dark cycle (LDLDL), transfer to continuous light (LDLLL), and transfer to continuous dark (LDDDD). Samples were taken every two hours starting at CT 5.5 with an extra sample 30 minutes after dawn. Before the transfer to continuous light/dark in the LDLLL and LDDDD experiment, samples were taken every 6 with an extra sample 30 minutes after dawn.
2013-05-30 | E-GEOD-47482 | biostudies-arrayexpress
Project description:Retinal function changes dramatically from day to night. Yet, clinical diagnosis, treatments, and experimental sampling occur during the day, leaving a significant gap in our understanding of the pathobiology occurring at night. While there is evidence that diabetes disrupts the circadian system that optimizes our physiology to the environmental light/dark cycle, the impact of such disruption is not well understood. This study investigates whether diabetes affects the retina's daily rhythm of gene expression to understand the pathobiology of diabetic retinopathy, a common complication of diabetes. Control and hyperglycemic littermate mice (Ins2Akita/J) were kept under a standard 12h:12h light/dark cycle until four months of age. Bulk mRNA sequencing was conducted in retinas collected every 4 hours throughout the 24 hr light/dark cycle. Computational approaches were used to detect rhythmicity, predict acrophase, identify differential rhythmic patterns, analyze phase set enrichment, and predict upstream regulators. The retinal transcriptome exhibited a tightly regulated rhythmic expression with a clear 12-hr axis of transcriptional rush, peaking at midday and midnight. The functions of day-peaking genes were enriched for DNA repair, RNA splicing, and ribosomal protein synthesis, whereas night-peaking genes were enriched for metabolic processes and growth factor signaling. Although the 12-hr transcriptional axis is retained in the diabetic retina, it was phase advanced by approximately 1-3 hours with a wider distribution. Upstream regulator analysis for the genes that showed phase shifts identified oxygen sensing mechanisms and HIF1alpha as regulators, but not the circadian clock, which remained in phase to the light/dark cycle. We propose a model in which early in diabetes, the diabetic retina experiences a ‘jet lag’ caused by the entrained circadian clock and its output being in one phase and metabolic pathways related to neuronal dysfunction and hypoxia driving advancement of gene expression to a different phase. Further studies are now required to evaluate the chronic implications of such internal jet lag for development of diabetic retinopathy.
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Project description:Genome wide rhythmic transcription under light/dark cycles is associated with sequential transcription of specific biological processes genes in Ostreococcus tauri. Transcriptional profiling of Ostreococcus tauri under light/dark cycles. In order to identify genes with a diurnal rhythm, cells entrained under 12:12 light/dark cycles were sampled every 3 hours for 27 hours with two overlapping time points at Time 9 (Light ON at Time 9; Light OFF at Time 21) in 3 independent experiments.
2010-04-20 | GSE16422 | GEO
Project description:In the unicellular cyanobacterium, Synechococcus elongatus PCC 7942, most of genes are downregulated in the dark, while 10% of genes are upregulated. Here, we employed high-density oligonucleotide arrays to explore comprehensive profiles of genome-wide Synechococcus gene expression in wild type and kaiABC-null strains under continuous dark (DD) conditions. We found that expression profile of a subset of genes on the genome in DD was dramatically affected by kaiABC-nullification, and the magnitude of dark-induction was dependent on time when cells were transferred from light to DD Keywords: timecourse data (0-12 h) under continuous darkness after dark:light cycles from Synechococcus elongatus PCC 7942 wild type and kaiABC-null strains Wild type (WT) and kaiABC-null (DkaiABC) S. elongatus PCC 7942 strains were analyzed under continuous dark (DD) conditions after two 12h:12h light:dark (LD) cycles using Affymetrix high-density oligonucleotide microarrays (GeneChip CustomExpress Arrays) representing predicted 2,515 protein-coding genes on the genome of Synechococcus elongatus PCC 6301, which can be used also to the almost homologous strain, S. elongatus PCC 7942: Two independent experiments in WT and Dkai strains under DD (hours 0, 0.5, 1, 2, 4, 8 and 12).
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Project description:Bacteria have evolved many strategies to spare energy when nutrients become scarce. One widespread such strategy is facultative phototrophy, which helps heterotrophs supplement their energy supply using light. Our knowledge on the impact that such behaviors have on bacterial fitness and physiology is, however, still limited. Here, we study how a representative of the genus Porphyrobacter, in which aerobic anoxygenic phototrophy is ancestral, responds to different light regimes under nutrient limitation. We show that bacterial survival in stationary phase relies on functional reaction centers and varies depending on the light regime. Under dark‑light alternance, our bacterial model presents a diphasic life history dependent on phototrophy: during dark phases, the cells inhibit DNA replication and part of the population lyses and releases nutrients, while subsequent light phases allow for the recovery and renewed growth of the surviving cells. We correlate these cyclic variations with a pervasive pattern of rhythmic transcription which reflects global changes in diurnal metabolic activity. Finally, we demonstrate that, compared to either a phototrophy null mutant or a bacteriochlorophyll a overproducer, the wild type strain is better adapted to natural environments, where regular dark‑light cycles are interspersed with additional accidental dark episodes. Overall, our results highlight the importance of light‑induced biological rhythms in a new model of aerobic anoxygenic phototroph representative of an ecologically important group of environmental bacteria.
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Project description:A daily temporal program for rhythmic expression of protein-coding and non-coding genes in response to light and dark in Synechocystis sp. PCC 6803
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Project description:Genome wide rhythmic transcription under light/dark cycles is associated with sequential transcription of specific biological processes genes in Ostreococcus tauri. Transcriptional profiling of Ostreococcus tauri under light/dark cycles. In order to identify genes with a diurnal rhythm, cells entrained under 12:12 light/dark cycles were sampled every 3 hours for 27 hours with two overlapping time points at Time 9 (Light ON at Time 9; Light OFF at Time 21) in 3 independent experiments. Two-conditions experiment, test situation (kinetic point) vs. Pool of each samples. Biological triplicates: 3 independant kinetics, 9 points per kinetics, Technical triplicates per array.
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