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Whole-cell response to nitrogen deprivation in the diatom Phaeodactylum tricornutum.

Alipanah L, Rohloff J, Winge P, Bones AM, Brembu T - J. Exp. Bot. (2015)

Bottom Line: Physiological and metabolite measurements indicated that the photosynthetic capacity and chlorophyll content of the cells decreased, while neutral lipids increased in N-deprived cultures.Following N deprivation, reduced biosynthesis and increased recycling of N compounds like amino acids, proteins, and nucleic acids was observed at the transcript level.The majority of the genes associated with photosynthesis and chlorophyll biosynthesis were also repressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.

No MeSH data available.


Related in: MedlinePlus

Transcriptional changes in genes related to TAG biosynthesis in response to N deprivation. Coloured squares indicate the regulation pattern of genes encoding putative enzymes functioning in the TAG biosynthetic pathway after 48 and 72h of N deprivation, compared with N-replete cultures. Squares with a diagonal line inside indicate non-significant regulation (P>0.05). The scale on the right represents gene expression ratio values, which were log2 transformed. Numbers indicate Phatr2 gene IDs. Gene ID 12726 (marked with an asterisk) belongs to the Phatr1 database (http://genome.jgi-psf.org/Phatr1/Phatr1.home.html).
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Figure 7: Transcriptional changes in genes related to TAG biosynthesis in response to N deprivation. Coloured squares indicate the regulation pattern of genes encoding putative enzymes functioning in the TAG biosynthetic pathway after 48 and 72h of N deprivation, compared with N-replete cultures. Squares with a diagonal line inside indicate non-significant regulation (P>0.05). The scale on the right represents gene expression ratio values, which were log2 transformed. Numbers indicate Phatr2 gene IDs. Gene ID 12726 (marked with an asterisk) belongs to the Phatr1 database (http://genome.jgi-psf.org/Phatr1/Phatr1.home.html).

Mentions: TAG biosynthetic pathways are illustrated in Fig. 7. Of three differentially regulated glycerol-3-phosphate dehydrogenases, transcript levels of Phatr2_36821 increased in N-deprived cells (Fig. 7). This enzyme consumes NAD(P)H to convert dihydroxyacetone phosphate, an intermediate in glycolysis, to glycerol-3-phosphate. Subsequent transfer of two acyl-CoAs to glycerol-3-phosphate by glycerol-3-phosphate acyltransferase and acyl-glycerol-3-phosphate acyltransferase (AGPAT) result in the formation of phosphatidic acid. Of the five detected isoforms of AGPAT, only one putative isoform (Phatr2_45551) displayed increased transcript levels 72h after deprivation, whereas three others (Phatr2_20460, Phatr2_11916, and LPT1) were suppressed. Phosphatidic acid is dephosphorylated to diacylglycerol, the main precursor of TAG. This process is catalysed by phosphatidic acid phosphatase; a putative PAP (Phatr2_40261) was weakly upregulated. Incorporation of the third fatty acyl-CoA into glycerol-3-phosphate backbone by diacylglycerol O-acyltransferase (DGAT) completes TAG formation. The mRNA levels of two isoforms of DGAT (Phatr2_43469 and Phatr2_9794) were induced in our experiment. Although we could detect TAG accumulation at both the molecular and physiological level, the transcript abundance of several TAG lipases was induced in N-deprived cells.


Whole-cell response to nitrogen deprivation in the diatom Phaeodactylum tricornutum.

Alipanah L, Rohloff J, Winge P, Bones AM, Brembu T - J. Exp. Bot. (2015)

Transcriptional changes in genes related to TAG biosynthesis in response to N deprivation. Coloured squares indicate the regulation pattern of genes encoding putative enzymes functioning in the TAG biosynthetic pathway after 48 and 72h of N deprivation, compared with N-replete cultures. Squares with a diagonal line inside indicate non-significant regulation (P>0.05). The scale on the right represents gene expression ratio values, which were log2 transformed. Numbers indicate Phatr2 gene IDs. Gene ID 12726 (marked with an asterisk) belongs to the Phatr1 database (http://genome.jgi-psf.org/Phatr1/Phatr1.home.html).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4588885&req=5

Figure 7: Transcriptional changes in genes related to TAG biosynthesis in response to N deprivation. Coloured squares indicate the regulation pattern of genes encoding putative enzymes functioning in the TAG biosynthetic pathway after 48 and 72h of N deprivation, compared with N-replete cultures. Squares with a diagonal line inside indicate non-significant regulation (P>0.05). The scale on the right represents gene expression ratio values, which were log2 transformed. Numbers indicate Phatr2 gene IDs. Gene ID 12726 (marked with an asterisk) belongs to the Phatr1 database (http://genome.jgi-psf.org/Phatr1/Phatr1.home.html).
Mentions: TAG biosynthetic pathways are illustrated in Fig. 7. Of three differentially regulated glycerol-3-phosphate dehydrogenases, transcript levels of Phatr2_36821 increased in N-deprived cells (Fig. 7). This enzyme consumes NAD(P)H to convert dihydroxyacetone phosphate, an intermediate in glycolysis, to glycerol-3-phosphate. Subsequent transfer of two acyl-CoAs to glycerol-3-phosphate by glycerol-3-phosphate acyltransferase and acyl-glycerol-3-phosphate acyltransferase (AGPAT) result in the formation of phosphatidic acid. Of the five detected isoforms of AGPAT, only one putative isoform (Phatr2_45551) displayed increased transcript levels 72h after deprivation, whereas three others (Phatr2_20460, Phatr2_11916, and LPT1) were suppressed. Phosphatidic acid is dephosphorylated to diacylglycerol, the main precursor of TAG. This process is catalysed by phosphatidic acid phosphatase; a putative PAP (Phatr2_40261) was weakly upregulated. Incorporation of the third fatty acyl-CoA into glycerol-3-phosphate backbone by diacylglycerol O-acyltransferase (DGAT) completes TAG formation. The mRNA levels of two isoforms of DGAT (Phatr2_43469 and Phatr2_9794) were induced in our experiment. Although we could detect TAG accumulation at both the molecular and physiological level, the transcript abundance of several TAG lipases was induced in N-deprived cells.

Bottom Line: Physiological and metabolite measurements indicated that the photosynthetic capacity and chlorophyll content of the cells decreased, while neutral lipids increased in N-deprived cultures.Following N deprivation, reduced biosynthesis and increased recycling of N compounds like amino acids, proteins, and nucleic acids was observed at the transcript level.The majority of the genes associated with photosynthesis and chlorophyll biosynthesis were also repressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.

No MeSH data available.


Related in: MedlinePlus