Dataset Information

Systems-level analysis of N-starvation induced modifications of carbon metabolism in a Chlamydomonas starchless mutant

ABSTRACT: To understand the molecular basis underlying increased triacylglycerol accumulation in starchless Chlamydomonas mutants, we undertook comparative time course transcriptomics of sta6 (CC-4348), a cw strain purported to represent the parental STA6 strain (CC-4349), and 3 independent STA6 strains (STA6-C2, STA6-C4 and STA6-C6, generated by complementation of sta6, CC-4565, –4566 and –4567) in the context of nitrogen deprivation. Despite the N starvation induced dramatic remodeling of the transcriptome, there are relatively few differences (5 x 102) between sta6 and STA6, the most dramatic of which are in the abundance of transcripts encoding key regulated or rate-limiting steps in central carbon metabolism, specifically ICL1, MAS1, TAL1, FBP1 and PCK1, suggestive of increased carbon movement towards hexosephosphate in sta6 by up-regulation of the glyoxylate pathway and gluconeogenesis. Enzyme assays validated the increase in isocitrate lyase and malate synthase activities. Targeted metabolite analysis indicates increased succinate and malate, increased Glc-6-P and decreased fructose-1,6-bisphosphate, which documents the impact of these changes. Comparisons of the independent datasets in multiple strains allowed the delineation of a sequence of events in a global N-starvation response in Chlamydomonas, starting within minutes with up-regulation of alternative N assimilation routes and carbohydrate synthesis and subsequently a more gradual up-regulation of genes encoding enzymes of TAG synthesis. Finally, genome re-sequencing analysis indicated that i) the deletion in sta6 extends into the neighboring gene, RBO1, and ii) a commonly-used STA6 strain (CC-4349) as well as the sequenced reference (CC-503) are not congenic with respect to sta6 (CC-4348), underscoring the importance of using complemented strains for more rigorous assignment of phenotype to genotype.

ORGANISM(S): Chlamydomonas reinhardtii

PROVIDER: GSE51602 | GEO | 2013/10/24

SECONDARY ACCESSION(S): PRJNA223676

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:To understand the molecular basis underlying increased triacylglycerol accumulation in starchless Chlamydomonas mutants, we undertook comparative time course transcriptomics of sta6 (CC-4348), a cw strain purported to represent the parental STA6 strain (CC-4349), and 3 independent STA6 strains (STA6-C2, STA6-C4 and STA6-C6, generated by complementation of sta6, CC-4565, M-bM-^@M-^S4566 and M-bM-^@M-^S4567) in the context of nitrogen deprivation. Despite the N starvation induced dramatic remodeling of the transcriptome, there are relatively few differences (5 x 102) between sta6 and STA6, the most dramatic of which are in the abundance of transcripts encoding key regulated or rate-limiting steps in central carbon metabolism, specifically ICL1, MAS1, TAL1, FBP1 and PCK1, suggestive of increased carbon movement towards hexosephosphate in sta6 by up-regulation of the glyoxylate pathway and gluconeogenesis. Enzyme assays validated the increase in isocitrate lyase and malate synthase activities. Targeted metabolite analysis indicates increased succinate and malate, increased Glc-6-P and decreased fructose-1,6-bisphosphate, which documents the impact of these changes. Comparisons of the independent datasets in multiple strains allowed the delineation of a sequence of events in a global N-starvation response in Chlamydomonas, starting within minutes with up-regulation of alternative N assimilation routes and carbohydrate synthesis and subsequently a more gradual up-regulation of genes encoding enzymes of TAG synthesis. Finally, genome re-sequencing analysis indicated that i) the deletion in sta6 extends into the neighboring gene, RBO1, and ii) a commonly-used STA6 strain (CC-4349) as well as the sequenced reference (CC-503) are not congenic with respect to sta6 (CC-4348), underscoring the importance of using complemented strains for more rigorous assignment of phenotype to genotype. The transcriptomes of five different Chlamydomonas strains (wild type CC-4349, sta6 mutant (CC-4348),and three indepdent STA6 strains (STA6-C2, STA6-C4 and STA6-C6) are profiled by RNA-Seq in timecourse experiments after the transition to minus nitrogen

Project description:We used Chlamydomonas microarray v2.0 to compare the time course expression profiles of two Chlamydomonas reinhardtii strains: wild-type WT and the high hydrogen producing mutant Stm6Glc4 during sulfur starvation induced hydrogen production. Major cellular reorganizations in photosynthetic apparatus, sulfur and carbon metabolism upon H2 production were confirmed as common to both strains. More importantly, our results pointed out factors which lead to the higher hydrogen production in the mutant including higher light sensitivity and lower competitions with hydrogenase by alternative electron sinks. Under S-starvation induced H2 producing conditions the induction of LHCSR3, a chlorophyll binding protein involving in non photochemical quenching, was significantly lower in Stm6Glc4 resulting in significant higher photodamage to photosystem II. Consequently, Stm6Glc4 had a shorter aerobic phase, consumed less starch reserves, and produced H2 earlier at higher rates than WT. We also showed that the loss of mitochondrial DNA-binding protein MOC1 in both knockdown and knockout mutant resulted in higher light sensitivity and improved H2 yield. Furthermore, by comparing our data with previously published ‘omics’ data, we were able to identify genes that responded specifically to either sulfur starvation, anaerobiosis or hydrogen production as well as to provide a more complete picture of S-deprived H2 production in the green alga C. reinhardtii. A total of 33 microarray hydridizations were performed covering samples taken during the course of S deprivation induced H2 producction. The samples included 4 time points in the high hydrogen producing mutant Stm6Glc4 (taken at 16, 28, 52 and 76h) and 6 time points in the wildtype CC-406 (taken at 16, 28, 52, 68, 92, 116h). Samples from each time point were compared directly with the sample taken prior to S starvation from the corresponding strain. Three biological replicates were tested at each time point.

Project description:The collaborative cross (CC) founder strains include five classical inbred laboratory strains (129S1/SvlmJ, A/J, C57BL/6J (B6), NOD/ShiLtJ, and NZO/HILtJ) and three wild-derived strains (CAST/EiJ, PWK/PhJ (PWK) and WSB/EiJ) The strains encompass 89% of the genetic diversity available in Mus musculus and about 10 to 20 times more genetic diversity than found in Homo sapiens. For more than 60 years the B6 strain has been used as the model strain for high ethanol preference/high consumption. However, another one of the CC founder strains, PWK, was identified as a high ethanol preference/high consumption strain. The current study determined how the transcriptomes of the B6 and PWK strains differed from the 6 low preference CC strains across 3 nodes of the brain addiction circuit. RNA-Seq data were collected from the central nucleus of the amygdala, the nucleus accumbens core and the prelimbic cortex. Differential expression (DE) analysis was performed in each of these brain regions for all 28 possible pairwise comparisons of the CC founder strains. Unique genes for each strain were identified by selecting for genes that differed significantly (false discovery rate (FDR) < 0.05) from all other strains in the same direction. B6 was identified as the most distinct inbred laboratory strain, having the highest number of total differently expressed genes (DEGs) and DEGs with high log fold change, and unique genes compared to other CC strains. Less than 50 unique DEGs were identified in common between B6 and PWK within all three brain regions, indicating the strains potentially represent two distinct genetic signatures for risk for high ethanol-preference. 238 DEGs were found to be commonly different between B6, PWK and the average expression of the remaining CC strains within all three regions. The commonly different up-expressed genes were significantly enriched (FDR < 0.001) among genes associated with neuroimmune function. These data compliment the observation that neuroimmune signaling is key to understanding alcohol use disorder and and support use of these 8 strains and the highly heterogeneous mouse populations derived from them to identify alcohol-related brain mechanisms and treatment targets.

Dataset Information

Systems-level analysis of N-starvation induced modifications of carbon metabolism in a Chlamydomonas starchless mutant

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets