Project description:Nannochloropsis oceanica CCMP1779 is a marine unicellular stramenopile and an emerging reference species for basic research on oleogenic microalgae with biotechnological relevance. We investigated its physiology and transcriptome under light/dark cycles. We observed oscillations in lipid content and a predominance of cell division in the first half of the dark phase. Globally, more than 60% of the genes cycled in N. oceanica CCMP1779, with gene expression peaking at different times of the day. Interestingly, the phase of expression of genes involved in certain biological processes was conserved across photosynthetic lineages. Furthermore, in agreement with our physiological studies we found the processes of lipid metabolism and cell division enriched in cycling genes. For example, there was tight coordination of genes involved in the lower part of glycolysis, fatty acid synthesis and lipid production at dawn preceding lipid accumulation during the day. Our results suggest that diel lipid storage plays a key role for N. oceanica CCMP1779 growth under natural conditions making this alga a promising model to gain a basic mechanistic understanding of triacylglycerol production in photosynthetic cells. Our data will help the formulation of new hypotheses on the regulation transcriptional control of cell growth and metabolism in Nannochloropsis. Nannochloropsis oceanica CCMP was entrained to 12:12 light:dark cycles and biological replicates collected every 3 hours for a cycle for a total of 16 samples.
Project description:Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high value lipid products. First success in applying reverse genetics makes Nannochloropsis species attractive models to investigate the cell and molecular biology and biochemistry of this fascinating organism group. (Principle findings) Here we present the assembly of the 28.7 Mb genome of Nannochloropsis oceanica CCMP1779. RNA sequencing data from N-replete and N-depleted growth conditions support a total of 11,973 genes, which in addition to automatic annotation were manually inspected to predict the biochemical repertoire for this organism. Among others, more than 100 genes putatively related to lipid metabolism, 114 predicted transcription factors and 109 transcriptional regulators were annotated. In addition, we provide protocols for the transformation of the sequenced strain. (Significance) The availability of genomic and transcriptomic data for Nannochloropsis oceanica CCMP1779, along with efficient transformation protocols provides a blueprint for future detailed gene functional analysis and phylogenetic comparison of Nannochloropsis species by a growing academic community focused on this genus. one sample each of nitrogen-replete and nitrogen-depleted conditions
Project description:Nannochloropsis oceanica CCMP1779 is a marine unicellular stramenopile and an emerging reference species for basic research on oleogenic microalgae with biotechnological relevance. We investigated its physiology and transcriptome under light/dark cycles. We observed oscillations in lipid content and a predominance of cell division in the first half of the dark phase. Globally, more than 60% of the genes cycled in N. oceanica CCMP1779, with gene expression peaking at different times of the day. Interestingly, the phase of expression of genes involved in certain biological processes was conserved across photosynthetic lineages. Furthermore, in agreement with our physiological studies we found the processes of lipid metabolism and cell division enriched in cycling genes. For example, there was tight coordination of genes involved in the lower part of glycolysis, fatty acid synthesis and lipid production at dawn preceding lipid accumulation during the day. Our results suggest that diel lipid storage plays a key role for N. oceanica CCMP1779 growth under natural conditions making this alga a promising model to gain a basic mechanistic understanding of triacylglycerol production in photosynthetic cells. Our data will help the formulation of new hypotheses on the regulation transcriptional control of cell growth and metabolism in Nannochloropsis.
Project description:Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high value lipid products. First success in applying reverse genetics makes Nannochloropsis species attractive models to investigate the cell and molecular biology and biochemistry of this fascinating organism group. (Principle findings) Here we present the assembly of the 28.7 Mb genome of Nannochloropsis oceanica CCMP1779. RNA sequencing data from N-replete and N-depleted growth conditions support a total of 11,973 genes, which in addition to automatic annotation were manually inspected to predict the biochemical repertoire for this organism. Among others, more than 100 genes putatively related to lipid metabolism, 114 predicted transcription factors and 109 transcriptional regulators were annotated. In addition, we provide protocols for the transformation of the sequenced strain. (Significance) The availability of genomic and transcriptomic data for Nannochloropsis oceanica CCMP1779, along with efficient transformation protocols provides a blueprint for future detailed gene functional analysis and phylogenetic comparison of Nannochloropsis species by a growing academic community focused on this genus.
Project description:We investigated light dependent gene expression changes in the marine ochrophyte Nannochloropsis oceanica CCMP1779. These algae have several putative blue light photoreceptors but appear to lack red light photoreceptors. To study early light signaling in N. oceanica and avoid as much as possible secondary downstream events, we quantified gene expression changes in dark-adapted cells after a short blue or red light pulse. More genes were differentially expressed under blue than under red light. In addition, fold change in expression was smaller for the red light-treated samples. For example, the median fold change of induced genes was 3 for blue light and 2.5 for red light. Moreover, hierarchical cluster analysis showed that gene expression after red light treatment was more similar to the dark control than after blue light treatment.