Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

RNA-seq of Chlamydomonas reinhardtii exposed to inorganic or methylmercury

ABSTRACT: This study aims at investigating the link between internalized inorganic or methyl Hg and the global expression of genes, obtained by high-throughput sequencing (RNA-Seq), in the microalga Chlamydomonas reinhardtii. Algal cells were exposed two hours in a simplified artificial medium spiked with series of inorganic Hg concentrations (0.1, 1, 100 nM Hg) or series of methyl Hg concentrations (0.05, 0.5, 5, 50 nM CH3Hg). Three biological replicates were assessed for each of the 8 tested conditions: Control, 3 Hg concentrations, 4 CH3Hg concentrations.

ORGANISM(S): Chlamydomonas reinhardtii

SUBMITTER: Rebecca Beauvais-Flueck

PROVIDER: E-GEOD-65109 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Cellular toxicity pathways of inorganic and methyl mercury in the green microalga Chlamydomonas reinhardtii.

Beauvais-Flück Rebecca R Slaveykova Vera I VI Cosio Claudia C

Scientific reports 20170814 1

Contamination by mercury (Hg) is a worldwide concern because of Hg toxicity and biomagnification in aquatic food webs. Nevertheless, bioavailability and cellular toxicity pathways of inorganic (IHg) and methyl-Hg (MeHg) remain poorly understood. We analyzed the uptake, transcriptomic, and physiological responses in the microalga Chlamydomonas reinhardtii exposed to IHg or MeHg. Bioavailability of MeHg was up to 27× higher than for IHg. Genes involved in cell processes, energy metabolism and tran ...[more]

PMID: 28808314

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Project description:Background: Microalgae are promising feedstocks for production of renewable biofuels and value-added bioproducts. Temperature and nitrogen supply are important environmental and nutritional factors affecting the growth and metabolism of microalgae, respectively. In this study, the growth and lipid accumulation of filamentous microalga Xanthonema hormidioides under different temperatures (5, 7, 10, 15, 20, 25, 27 and 30℃) and initial nitrogen concentrations (3, 9, 18 mM) were investigated, and its adaptive mechanisms of tolerance to low temperature and nitrogen stress were analysis by proteomics. Results: The optimum temperature range for the growth of X. hormidioides was between 15℃ and 20℃, and the algal cells had slow growth rate at 5℃ and could not survive at 30℃. The maximum biomass concentration was 11.73 g L-1 under the temperature of 20℃, and the highest total lipid content was 56.63% of dry weight. Low temperature did not change the fatty acids profiles but promoted the accumulation of unsaturated fatty acids of X. hormidioides. The maximum contents of palmitoleic acid, eicosapentaenoic acid and total fatty acid were 23.64%, 2.49% and 41.14% of dry weight, respectively. Proteomics was performed under three temperature (7、15、25℃), two nitrogen concentrations (3 and 18 mM) and two cultivation times (day3 and 12). A total of 6503 proteins were identified. In the low temperature, photosynthesis related proteins were down-regulation to protect the photosynthetic apparatus. The up-regulation of key enzymes DGAT and PDAT demonstrated the accumulation of TAGs under low nitrogen treatment. The proteins related to ribosome, phosphatidylinositol signaling system, antioxidant system and cold shock proteins (CSPs) in X. hormidioides were co-up-regulate under the treatment of low temperature, which can alleviate the damages induced by temperature stress and maintain the normal growth and metabolism of algal cells. Conclusions: X. hormidioides is a psychrotolerant microalga. It is an oleaginous filamentous microalga containing hyper palmitoleic acid and a certain amount of eicosapentaenoic acid with great potential for biofuel development, as well as for applications in nutritional health products and other industries.

Project description:The hydrothermal vent gammaproteobacterium Thiomicrospira crunogena inhabits an unstable environment and must endure dramatic sweeps in habitat chemistry. This sulfur chemolithoautotroph responds to changes in dissolved inorganic carbon (DIC; = CO2 + HCO3- + CO3-2) availability with a carbon concentrating mechanism (CCM), in which whole-cell affinity for DIC, as well as the intracellular DIC concentration, increase substantially under DIC-limitation. To determine whether this CCM is regulated at the level of transcription, cells cultivated under high-DIC conditions in chemostats were resuspended in growth medium with low concentrations of DIC, and CCM development was tracked in the presence and absence of RNA polymerase inhibitor rifampicin. The induction of the CCM, as measured by silicone oil centrifugation, was hindered in the presence of rifampicin. Similar results were observed for carboxysome gene transcription and assembly, as assayed by qRT-PCR and transmission electron microscopy, respectively. Genome-wide transcription patterns, assayed via microarrays, were compared for cells grown under DIC-limitation versus ammonia limitation. In addition to carboxysome genes, two novel genes (Tcr_1019 and Tcr_1315), present in other organisms including chemolithoautotrophs, but whose function(s) have not been elucidated in any organism, were found to be upregulated under low-DIC conditions. Likewise, under ammonia limitation, in addition to the expected enhancement of ammonia transporter and PII-gene transcription, the transcription of two novel genes was measurably enhanced (Tcr_0466 and Tcr_2018). Upregulation of all four genes was verified via qRT-PCR (Tcr_1019: 4-fold; Tcr_1315: ~7-fold; Tcr_0466: >200-fold; Tcr_2018: 7-fold), suggesting novel components are part of the response to nutrient limitation by this organism. In this study Thiomicrospira crunogena cells were grown under inorganic carbon limitation and ammonia limitation (high inorganic carbon concentrations) to examine genome wide transcription responses

Dataset Information

RNA-seq of Chlamydomonas reinhardtii exposed to inorganic or methylmercury

Publications

Cellular toxicity pathways of inorganic and methyl mercury in the green microalga Chlamydomonas reinhardtii.

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