ABSTRACT: A mapping population of Brassica rapa (BraIRRI, IMB211xR500) was grown under four external calcium and magnesium concentrations in controlled conditions. RNA was extracted and hybridised to the Affymetrix Brassica Exon 1.0 ST array. The aim of the experiment was to identify cis- and trans- expression quantitative trait loci. In total 279 samples were analysed. The parents of the mapping population were grown at all four treatment levels (LL, HL, LH, HH) with three biological replicates per treatment, plus 12 technical replicates (n=36). A 2x2 combination of external calcium and magnesium concentrations were imposed to give four treatments (LL, HL, LH, HH) as follows: the high (H) concentrations were 3.5 g L-1 (24 mM) CaCl2 and 3.04 g L-1 (15 mM) MgCl2 and the low (L) concentrations were 0.44 g L-1 (3 mM) CaCl2 and 0.2 g L-1 (1 mM) MgCl2 For the mapping population (total = 85 lines), 85 lines were analysed for the LL treatment, 81 lines were analysed for the LH treatment and 65 lines were analysed for the HL treatment. Twelve technical replicates were also analysed.
Project description:To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the transcriptomic responses of Synechococcus sp. WH7803 acclimated to low (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H202) or methylviologen (MV). Cultures were acclimated during many generations to continuous low light (LL, 18 ?mol photons m-2 s-1, hereafter LL cells) and high light (HL, 250 ?mol photons m-2 s-1, hereafter HL cells) provided by Sylvania Daylight 58W/154 fluorescent bulbs. For all stress experiments performed in this study, exponentially growing cultures (1 to 3 x 107 cells mL-1), were split into subcultures and submitted to oxidative stress by addition of H2O2 or MV and harvested when PSII quantum yield fell to half of the initial value. For H2O2 experiments, this level of PSII photoinactivation was reached 2 h after submitting LL and HL cultures to 750 M and 25 M respectively. Because of the large divergence in dose and kinetics responses to MV between LL- and HL cells, it was not possible to find MV concentrations leading to 50 % decrease of quantum yield at the same time for both light acclimations. Thus, array analyses for MV were performed on HL and LL cultures incubated at the same MV concentration (50 M) but harvested once PSII quantum yield was halved, i.e. after 1 and 3.5 h of stress respectively. All hybridizations were performed on 4 independent biological replicates and using as reference sample a pool of RNA from all samples investigated in this study. Pairwise comparison were performed to analyze the stress induced by either H2O2 or MV on both LL- and HL cultures (i.e. LL-Ct vs. LL+MV, LL-Ct vs. LL+H2O2, HL-Ct vs. HL+MV, HL-Ct vs. HL+H2O2) as well as to compare the steady state acclimation to different light conditions (i.e. LL-Ct vs. HL-Ct).
Project description:Transcriptional profiling of mice fed a diet deficient in selenium and folate during weaning and in utero (LL), a diet deficient in selenium and folate during weaning but not in utero (HL), a diet sufficient in selenium and folate during weaning but deficient in utero (LH), and a diet sufficient in selenium and folate during weaning and in utero (HH)
Project description:Corals continuously adjust to short term variation in light availability on shallow reefs. Long-term light alterations can also occur due to natural and anthropogenic stressors, as well as management interventions such as coral transplantation. Although short term photophysiological responses are relatively well-understood in corals, little information is available regarding photoacclimation dynamics over weeks of altered light availability. We coupled photophysiology and metabolomic profiling to explore changes that accompany longer-term photoacclimation in a key Great Barrier Reef coral species (Acropora muricata). High (HL) and low light (LL) acclimated corals were collected from the reef and reciprocally exposed to high and low light ex situ. Rapid light curves using Pulse Amplitude Modulation (PAM) fluorometry revealed photophysiological acclimation of LL to HL and HL to LL shifted corals within 21 days. A subset of colonies sampled at 7 and 21 days for untargeted LC-MS and GC-MS metabolomic profiling revealed metabolic reorganization before acclimation was detected using PAM fluorometry. Metabolomic shifts were more pronounced for LL to HL treated corals than their HL to LL counterparts. Compounds driving metabolomic separation between HL-exposed and LL control colonies included amino acids, organic acids, fatty acids and sterols. Reduced glycerol and campesterol suggest decreased translocation of photosynthetic products from symbiont to host in LL to HL shifted corals, with concurrent increases in fatty acid abundance indicating reliance on stored lipids for energy. We discuss how these data provide novel insight into environmental regulation of metabolism and implications for management strategies that drive rapid changes in light availability.
Project description:Transcriptional profiling of mice fed a diet deficient in selenium and folate during weaning and in utero (LL), a diet deficient in selenium and folate during weaning but not in utero (HL), a diet sufficient in selenium and folate during weaning but deficient in utero (LH), and a diet sufficient in selenium and folate during weaning and in utero (HH) 2 colour microarray, reference design. Biological replicates: 6 per treatment group. The reference RNA was extracted from a whole pregnant C57 mouse and foetus. The whole body was homogenised and RNA was extracted using an AllPrep(r) DNA/RNA/Protein mini kit (Qiagen, Cat number 80004).
Project description:Peripheral light harvesting (LH) antenna complexes have been studied extensively in the purple nonsulfur bacterium Rhodopseudomonas palustris because it produces different types of LH complexes under high light intensities (LH2 complex) and low light intensities (LH3 and LH4 complex). The ability of R. palustris to alter its peripheral LH complexes in response to changes in light intensity is attributed to the multiple operons that encode the a and b peptides that make up these complexes, whose expression is affected by light intensity, light quality, and oxygen tension. However, low resolution structures, amino acid similarities between the complexes, and a lack of transcriptional analysis made it difficult to determine the LH complexes composition and functions under different light intensities. It was also unclear how much diversity of the R. palustris LH complexes exists in nature.Results: To gain insight into the composition of the LH complexes, their function under high light intensities and low light intensities, and their prevalence in the environment we undertook an integrative genomics approach using 15 closely related R. palustris strains isolated from the environment and 5 R. palustris ecotypes whose genomes have been sequenced. We sequenced the genomes for the 15 closely related strains and using RNA-seq carried out transcriptomic analysis on all 20 strains grown under high light intensity and low light intensity. We were able to determine that even closely related R. palustris strains had differences in their pucBA gene content and expression, even under the same growth conditions. We also found that the LH2 complex could compensate for the lack of an LH4 complex under LL intensities but not under extremely LL intensities. Conclusions: This is the first time an integrative genomics approach has been used to study light harvesting in the environment. The variation observed in LH gene composition and expression in environmental isolates of R. palustris likely reflects how these strains have adapted to specific light conditions in the environment. We have also shown that there is redundancy between some of the LH complexes under certain light intensities, which may partially explain why multiple operons encoding LH complexes have evolved and been maintained in R. palustris. Examing the variation observed in LH gene composition and expression in various environmental isolates
Project description:Prymnesium parvum is regarded as one of the most notorious harmful algal bloom (HAB) species worldwide. In recent years, it has frequently formed toxic blooms in coastal and brackish waters of America, Europe, Australia, Africa and Asia, causing large-scale mortalities of wild and cultured fish and other gill-breathing animals. In the last decade, blooms of P. parvum have expanded to inland fresh waters in the USA, presumably due to changes in environmental conditions. The aim of the experiment was to establish the gill transcriptomic responses to P. parvum in rainbow trout. We used 2 different concentrations of P. parvum and identified fish with low and moderate responses to the algae. Based on the dose of and the fish response, fish were classified into 4 groups with high exposure/moderate response (HM), high exposure/low response (HL), low exposure/low response (LL) and control group (C) with no exposure/no response. Gene expression profiling of the gill tissue was performed using a microarray platform developed and validated for rainbow trout.
Project description:HL-60 is a human promyelocytic leukemia cell line and differentiated HL-60 is an alternative to human primary neutrophils. The transcriptomic profile of undifferentiated HL-60 and dimethyl sulfoxide-differentiated HL-60 were determined at 4 and 24 hours after stimulation with high and low concentrations of Staphylococcus aureus lipoteichoic acids.
Project description:Plant thylakoid membranes contain hundreds of proteins closely interplaying to cope with ever-changing environmental conditions. We investigated how P. sativum (pea) grown at different irradiances optimizes light-use efficiency through the differential accumulation of thylakoid proteins. Thylakoid membranes from plants grown under limiting (LL), normal (NL) and high (HL) light intensity were characterized by combining chlorophyll fluorescence measurements with quantitative proteomic analysis. Protein sequences retrieved from available transcriptomic data considerably improved the protein profiling. We found that increasing growth irradiance affects the electron transport kinetics but not Photosystem (PS) I and II relative abundance. Two acclimation strategies were evident comparing plants acclimated to LL with higher irradiances: 1) in NL, plants turn on photoprotective responses mostly regulating the PSII light-harvesting capacity either accumulating Lhcb4.3 or favouring the xanthophyll cycle; 2) in HL, plants reduce the LHCII pool and enhance the PSII repair cycle. At increasing growth irradiance, plants increase the accumulation of ATP synthase and boost the electron transport to finely tune the ΔpH across the membrane and adjust the thylakoid architecture to optimize protein trafficking. Our results provide a quantitative snapshot on how plants coordinate light-harvesting, electron transport and protein synthesis adjusting the thylakoid membrane proteome in a light-dependent manner
Project description:Peripheral light harvesting (LH) antenna complexes have been studied extensively in the purple nonsulfur bacterium Rhodopseudomonas palustris because it produces different types of LH complexes under high light intensities (LH2 complex) and low light intensities (LH3 and LH4 complex). The ability of R. palustris to alter its peripheral LH complexes in response to changes in light intensity is attributed to the multiple operons that encode the a and b peptides that make up these complexes, whose expression is affected by light intensity, light quality, and oxygen tension. However, low resolution structures, amino acid similarities between the complexes, and a lack of transcriptional analysis made it difficult to determine the LH complexes composition and functions under different light intensities. It was also unclear how much diversity of the R. palustris LH complexes exists in nature.Results: To gain insight into the composition of the LH complexes, their function under high light intensities and low light intensities, and their prevalence in the environment we undertook an integrative genomics approach using 15 closely related R. palustris strains isolated from the environment and 5 R. palustris ecotypes whose genomes have been sequenced. We sequenced the genomes for the 15 closely related strains and using RNA-seq carried out transcriptomic analysis on all 20 strains grown under high light intensity and low light intensity. We were able to determine that even closely related R. palustris strains had differences in their pucBA gene content and expression, even under the same growth conditions. We also found that the LH2 complex could compensate for the lack of an LH4 complex under LL intensities but not under extremely LL intensities. Conclusions: This is the first time an integrative genomics approach has been used to study light harvesting in the environment. The variation observed in LH gene composition and expression in environmental isolates of R. palustris likely reflects how these strains have adapted to specific light conditions in the environment. We have also shown that there is redundancy between some of the LH complexes under certain light intensities, which may partially explain why multiple operons encoding LH complexes have evolved and been maintained in R. palustris.