Project description:Nitrogen starvation is an efficient environmental pressure used to increase lipid accumulation and oil droplet formation in microalgal cells. Various studies focused on metabolic changes occurring in microalgae in nitrogen starvation conditions, but the mechanisms at the basis of these changes are not completely understood. Between microalgae, green algae, with more than 7000 species growing in a variety of habitats, have been frequently studied for energy purposes, but also as source of bioactive extracts/compounds. In this study, de novo transcriptome of the green algae Tetraselmis suecica has been performed in order to (1) deeply study its response to nitrogen starvation, (2) to look for enzymes with antioxidant capacity and for polyketide synthases (PKSs), (3) if present, to evaluate if nutrient starvation can influence their expression levels.
Project description:This data was generated to identify the molecular pathways responsible for nitrous oxide synthesis by the green algae Chlamydomonas reinhardtii, when supplied with nitrite under aerobic conditions (oxia). RNA samples were collected at three time points, 15 min, 3 hours, and 24 hours after the start of the experiment. The control and treatment groups were grown under the same conditions, except treatment group was supplied with 10mM nitrite at time 0. Illumina TruSeq stranded RNA libraries were synthesised from the resulting RNA before sequencing on a HiSeq2500 (125bp). The resulting sequence run generated 241,151,809 paired-end 125bp reads, of which 200,946,839 remained following quality filtering. The short data was mapped to the published genome and read counts were generated with HT-Seq count with the default settings. The raw read count data was analysed by DESeq2 in order to identify genes differentially expressed during nitrous oxide production.
Project description:Cypermethrin (CYP) is one of the most widely used pesticides in large scale for agricultural and domestic purpose and the residue often seriously affects aquatic system. Environmental pollutants induced protein changes in organisms could be detected by proteomics, leading to discovery of potential biomarkers and understanding of mode of action. While proteomics investigations of CYP stress in some animal models have been well studied, few reports about the effects of exposure to CYP on algae proteome were published. To determine CYP effect in algae, the impact of various dosages (0.001 µg/L, 0.01 µg/L and 1 µg/L) of CYP on green algae Chlorella Vulgaris for 24h and 96h were investigated by using iTRAQ quantitative proteomics technique. A total of 162 and 198 proteins were significantly altered after CYP exposure for 24h and 96h, respectively. Overview of iTRAQ results indicated that the influence of CYP on algae protein might be dosage-dependent. Functional analysis of differentially expressed proteins showed that CYP could induce protein alterations related to photosynthesis, stress responses and carbohydrates metabolism. This study provides a comprehensive view of complex mode of action of algae under CYP stress and highlights several potential biomarkers for further investigation of pesticides exposed plant and algae.
Project description:We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions. Continuous, axenic culturing of P. tricornutum was done as described in Nymark et al. (2009). The cultures were incubated at 15M-BM-0C under cool white fluorescent light (Philips TLD 36W/96) providing a scalar irradiance (EPAR) of 100 M-NM-<mol m-2 s-1 under continuous white light (CWL) conditions. Upon the onset of the experiment the cultures were synchronized by 48 h dark-treatment (D48). Thereafter the algae were exposed to blue light (BL), green light (GL) or red light (RL) provided by a waveband specific LED panel (SL3500, Photon Systems Instruments). The algae were exposed to 0.5 h, 6 h or 24 h of: 1) 230 M-NM-<mol m-2 s-1 of RL, 2) 100 M-NM-<mol m-2 s-1 of GL, 3) 50 M-NM-<mol m-2 s-1 of BL or 4) 100 M-NM-<mol m-2 s-1 of WL respectively. Three biological replicas for each of the treatments were harvested. Data for the white light exposure and 48h dark treatment is described in GSE42039, PMID: 23520530.
Project description:The objective was to identify functional genes encoded by Fungi and fungal-like organisms to assess putative ecological roles Using the GeoChip microarray, we detected fungal genes involved in the complete assimilation of nitrate and the degradation of lignin, as well as evidence for Partitiviridae (a mycovirus) that likely regulates fungal populations in the marine environment. These results demonstrate the potential for fungi to degrade terrigenously-sourced molecules, such as permafrost and compete with algae for nitrate during blooms. Ultimately, these data suggest that marine fungi could be as important in oceanic ecosystems as they are in freshwater environments.