Lipidomic profiling of the developing kernel clarifies the lipid metabolism of Paeonia ostii.

Lipid components in the developing kernel of Paeonia ostii were determined, and the fatty acid (FA) distributions in triacylglycerol and phospholipids were characterized. The lipids in the kernel were mainly phospholipids (43%), neutral glycerides (24%), fatty acyls (26%), and sphingolipids (4.5%). The dominant neutral glycerides were TAG and diacylglycerol. The PL components included phosphatidic acid, phosphatidyl glycerol, phosphatidyl choline, phosphatidyl serine, phosphatidyl inositol, and phosphatidyl ethanolamine. As the kernel developed, the profiles of the molecular species comprising TAG and PL changed, especially during the earlier phases of oil accumulation. During rapid oil accumulation, the abundances of sphingosine-1-phosphate, pyruvic acid, stearic acid, and alpha-linolenic acid changed significantly; the sphingolipid metabolism and unsaturated FAs biosynthesis pathways were significantly enriched in these differentially abundant metabolites. Our results improve our understanding of lipid accumulation in tree peony seeds, and provide a framework for the analysis of lipid metabolisms in other oil crops.

Transcriptomic analysis of α-linolenic acid content and biosynthesis in Paeonia ostii fruits and seeds.

BACKGROUND: Paeonia ostii is a potentially important oilseed crop because its seed yield is high, and the seeds are rich in α-linolenic acid (ALA). However, the molecular mechanisms underlying ALA biosynthesis during seed kernel, seed testa, and fruit pericarp development in this plant are unclear. We used transcriptome data to address this knowledge gap. RESULTS: Gas chromatograph-mass spectrometry indicated that ALA content was highest in the kernel, moderate in the testa, and lowest in the pericarp. Therefore, we used RNA-sequencing to compare ALA synthesis among these three tissues. We identified 227,837 unigenes, with an average length of 755 bp. Of these, 1371 unigenes were associated with lipid metabolism. The fatty acid (FA) biosynthesis and metabolism pathways were significantly enriched during the early stages of oil accumulation in the kernel. ALA biosynthesis was significantly enriched in parallel with increasing ALA content in the testa, but these metabolic pathways were not significantly enriched during pericarp development. By comparing unigene transcription profiles with patterns of ALA accumulation, specific unigenes encoding crucial enzymes and transcription factors (TFs) involved in de novo FA biosynthesis and oil accumulation were identified. Specifically, the bell-shaped expression patterns of genes encoding SAD, FAD2, FAD3, PDCT, PDAT, OLE, CLE, and SLE in the kernel were similar to the patterns of ALA accumulation in this tissue. Genes encoding BCCP, BC, KAS I- III, and FATA were also upregulated during the early stages of oil accumulation in the kernel. In the testa, the upregulation of the genes encoding SAD, FAD2, and FAD3 was followed by a sharp increase in the concentrations of ALA. In contrast, these genes were minimally expressed (and ALA content was low) throughout pericarp development. CONCLUSIONS: We used three tissues with high, moderate, and low ALA concentrations as an exemplar system in which to investigate tissue-specific ALA accumulation mechanisms in P. ostii. The genes and TFs identified herein might be useful targets for future studies of ALA accumulation in the tree peony. This study also provides a framework for future studies of FA biosynthesis in other oilseed plants.

[Effect of magnesium deficiency on photosynthetic physiology and triacylglyceride (TAG) accumulation of Chlorella vulgaris].

As an excellent biological resource, Chlorella has wide applications for production of biofuel, bioactive substances and water environment restoration. Therefore, it is very important to understand the photosynthetic physiology characteristics of Chlorella. Magnesium ions play an important role in the growth of microalgae, not only the central atom of chlorophyll, but also the cofactor of some key enzyme in the metabolic pathway. A laboratory study was conducted to evaluate the effects of magnesium deficiency on several photosynthetic and physiological parameters and the triacylglyceride (TAG) accumulation of the green alga, Chlorella vulgaris, in the photoautotrophic culture process. Chlorella vulgaris biomass, protein, chlorophyll a and chlorophyll b contents decreased by 20%, 43.96%, 27.52% and 28.07% in response to magnesium deficiency, while the total oil content increased by 19.60%. Moreover, magnesium deficiency decreased the maximal photochemical efficiency F(v)/F(m) by 22.54%, but increased the non-photochemical quenching parameters qN. Our results indicated the decline of chlorophyll caused by magnesium, which affected the photosynthesis efficiency, lead to the growth inhibition of Chlorella vulgaris and affected the protein synthesis and increased the triacylglyceride (TAG) accumulation.

Novel neutrophil inhibitory factor homologue in the buccal gland secretion of Lampetra japonica.

Abstract To identify the functional gene fragment, a neutrophil inhibitory factor (NIF) like protein was found in the buccal gland of Lampetra japonica, suggesting that this related lamprey protein represents a novel class of integrin receptor antagonists. The recombinant Lampetra japonica-NIF like (rLj-NIF) was identified by SDS-PAGE and purified by using His·Bind affinity chromatography. Effect of rLj-NIF on neutrophil migration suggested that rLj-NIF can act as a neutrophil inhibitory factor. Besides that, oxidative burst activity of neutriphil was tested by flow cytometry using dihydrorhodamine (DHR123) as a fluorogenic substrate, and the data suggested that the mean fluorescence intensity significantly decreased compared with positive controls (p<0.01). All above results indicated that rLj-NIF could also prevent the binding of ß2 integrins to the surface of PMN and its FITC-labeled monoclonal antibodies (p<0.05). These data suggest that Lampetra japonica-NIF like protein is secreted by the stage of the parasite at the site of attachment. rLj-NIF plays an essential role in physiological reaction of neutrophil by a novel class of ß2 integrin receptor antagonists. The activity of immunosuppressant of L. japonica-NIF could have potential medicinal value in anti-inflammation and therapy of autoimmune diseases.