Joint interactions of carbon and nitrogen metabolism dominated by bicarbonate and nitrogen in Orychophragmus violaceus and Brassica napus under simulated karst habitats

Enhancing CO2 fixation by microalgae in a Photobioreactor: Molecular mechanisms with exogenous carbonic anhydrase

Microalgae biotechnology holds great potential for mitigating CO2 emissions, yet faces challenges in commercialization due to suboptimal photosynthetic efficiency. This study presents an innovative approach to improve CO2 mass transfer efficiency in microalgae using carbonic anhydrase (CA) in an internal LED flexible air-lift photobioreactor. Optimal conditions initial inoculation with 3.55 × 106 cells/mL and 20 % CO2 concentration, complemented by white LED lighting in Chlorella sp. CA regulated intracellular composition, enhancing chlorophyll, lipid, and protein contents. Metabolomics revealed elevated malic and succinic acids, associated with increased Ribulose 1,5-bisphosphate carboxylase oxygenase (RuBisCO) and Acetoacetyl coenzyme A (Acetyl-CoA) activities, facilitating efficient carbon fixation. CA also mitigated cellular oxidative stress by reducing reactive oxygen species (ROS). Furthermore, CA improved extracellular electron acceptor with currents surpassed CK. This CA-based microalgae biotechnology provides a foundation for future commercial applications, addressing CO2 emissions.

Integrated metabolome and transcriptome analysis reveals the regulatory mechanism of low nitrogen-driven biosynthesis of saponins and flavonoids in Panax notoginseng

BACKGROUND

Nitrogen (N) is an important macronutrient involved in the biosynthesis of primary and secondary metabolites in plants. However, the metabolic regulatory mechanism of low-N-induced triterpenoid saponin and flavonoid accumulation in rhizomatous medicinal Panax notoginseng (Burk.) F. H. Chen remains unclear.

METHODS

To explore the potential regulatory mechanism and metabolic basis controlling the response of P. notoginseng to N deficiency, the transcriptome and metabolome were analysed in the roots.

RESULTS

The N content was significantly reduced in roots of N0-treated P. notoginseng (0 kg·N·667 m-2). The C/N ratio was enhanced in the N-deficient P. notoginseng. N deficiency promotes the accumulation of amino acids (L-proline, L-leucine, L-isoleucine, L-norleucine, L-arginine, and L-citrulline) and sugar (arabinose, xylose, glucose, fructose, and mannose), thus providing precursor metabolites for the biosynthesis of flavonoids and triterpenoid saponins. Downregulation of key structural genes (PAL, PAL3, ACC1, CHS2, PPO, CHI3, F3H, DFR, and FGT), in particular with the key genes of F3H, involved in the flavonoid biosynthesis pathway possibly induced the decrease in flavonoid content with increased N supply. Notoginsenoside R1, ginsenoside Re, Rg1, Rd, F1, R1 + Rg1 + Rb1 and total triterpenoid saponins were enhanced in the N0 groups than in the N15 (15 kg·N·667 m-2) plants. Higher phosphoenolpyruvate (an intermediate of glycolyticwith pathway metabolism) and serine (an intermediate of photorespiration) levels induced by N deficiency possibly promote saponin biosynthesis through mevalonic acid (MVA) and methylerythritol (MEP) pathways. Genes (MVD2, HMGS, HMGR1, HMGR2, DXR, and HMGR1) encoding the primary enzymes HMGS, HMGR, DXR, and MVD in the MVA and MEP pathways were significantly upregulated in the N0-treated P. notoginseng. The saponin biosynthesis genes DDS, DDS, CYP716A52, CYP716A47, UGT74AE2, and FPS were upregulated in the N-deficient plants. Upregulation of genes involved in saponin biosynthesis promotes the accumulation of triterpenoid saponins in the N0-grown P. notoginseng.

CONCLUSIONS

N deficiency enhances primary metabolisms, such as amino acids and sugar accumulation, laying the foundation for the synthesis of flavonoids and triterpenoid saponins in P. notoginseng. F3H, DDS, FPS, HMGR, HMGS and UGT74AE2 can be considered as candidates for functional characterisation of the N-regulated accumulation of triterpenoid saponins and flavonoids in future.

Intergrative metabolomic and transcriptomic analyses reveal the potential regulatory mechanism of unique dihydroxy fatty acid biosynthesis in the seeds of an industrial oilseed crop Orychophragmus violaceus

BACKGROUND

Orychophragmus violaceus is a potentially important industrial oilseed crop due to the two 24-carbon dihydroxy fatty acids (diOH-FA) that was newly identified from its seed oil via a 'discontinuous elongation' process. Although many research efforts have focused on the diOH-FA biosynthesis mechanism and identified the potential co-expressed diacylglycerol acyltranferase (DGAT) gene associated with triacylglycerol (TAG)-polyestolides biosynthesis, the dynamics of metabolic changes during seed development of O. violaceus as well as its associated regulatory network changes are poorly understood.

RESULTS

In this study, by combining metabolome and transcriptome analysis, we identified that 1,003 metabolites and 22,479 genes were active across four stages of seed development, which were further divided into three main clusters based on the patterns of metabolite accumulation and/or gene expression. Among which, cluster2 was mostly related to diOH-FA biosynthesis pathway. We thus further constructed transcription factor (TF)-structural genes regulatory map for the genes associated with the flavonoids, fatty acids and diOH-FA biosynthesis pathway in this cluster. In particular, several TF families such as bHLH, B3, HD-ZIP, MYB were found to potentially regulate the metabolism associated with the diOH-FA pathway. Among which, multiple candidate TFs with promising potential for increasing the diOH-FA content were identified, and we further traced the evolutionary history of these key genes among species of Brassicaceae.

CONCLUSION

Taken together, our study provides new insight into the gene resources and potential relevant regulatory mechanisms of diOH-FA biosynthesis uniquely in seeds of O. violaceus, which will help to promote the downstream breeding efforts of this potential oilseed crop and advance the bio-lubricant industry.

Combined genomics to discover genes associated with tolerance to soil carbonate

Carbonate-rich soils limit plant performance and crop production. Previously, local adaptation to carbonated soils was detected in wild Arabidopsis thaliana accessions, allowing the selection of two demes with contrasting phenotypes: A1 (carbonate tolerant, c+) and T6 (carbonate sensitive, c-). Here, A1(c+) and T6(c - ) seedlings were grown hydroponically under control (pH 5.9) and bicarbonate conditions (10 mM NaHCO3 , pH 8.3) to obtain ionomic profiles and conduct transcriptomic analysis. In parallel, A1(c+) and T6(c - ) parental lines and their progeny were cultivated on carbonated soil to evaluate fitness and segregation patterns. To understand the genetic architecture beyond the contrasted phenotypes, a bulk segregant analysis sequencing (BSA-Seq) was performed. Transcriptomics revealed 208 root and 2503 leaf differentially expressed genes in A1(c+) versus T6(c - ) comparison under bicarbonate stress, mainly involved in iron, nitrogen and carbon metabolism, hormones and glycosylates biosynthesis. Based on A1(c+) and T6(c - ) genome contrasts and BSA-Seq analysis, 69 genes were associated with carbonate tolerance. Comparative analysis of genomics and transcriptomics discovered a final set of 18 genes involved in bicarbonate stress responses that may have relevant roles in soil carbonate tolerance.

The potential role of reprogrammed glucose metabolism: an emerging actionable codependent target in thyroid cancer

Although the incidence of thyroid cancer is increasing year by year, most patients, especially those with differentiated thyroid cancer, can usually be cured with surgery, radioactive iodine, and thyroid-stimulating hormone suppression. However, treatment options for patients with poorly differentiated thyroid cancers or radioiodine-refractory thyroid cancer have historically been limited. Altered energy metabolism is one of the hallmarks of cancer and a well-documented feature in thyroid cancer. In a hypoxic environment with extreme nutrient deficiencies resulting from uncontrolled growth, thyroid cancer cells utilize "metabolic reprogramming" to satisfy their energy demand and support malignant behaviors such as metastasis. This review summarizes past and recent advances in our understanding of the reprogramming of glucose metabolism in thyroid cancer cells, which we expect will yield new therapeutic approaches for patients with special pathological types of thyroid cancer by targeting reprogrammed glucose metabolism.

Quantification of Glucose Metabolism and Nitrogen Utilization in Two Brassicaceae Species under Bicarbonate and Variable Ammonium Soil Conditions

In karst habitats under drought conditions, high bicarbonate (high pH), and an abundant nitrate soil environment, bicarbonate regulates the glycolysis (EMP) and pentose phosphate pathways (PPP), which distribute ATP and NADPH, affecting nitrate (NO3-) and ammonium (NH4+) utilization in plants. However, the relationship between EMP PPP and NO3-, and NH4+ utilization and their responses to bicarbonate and variable ammonium still remains elusive. In this study, we used Brassica napus (Bn, a non-karst-adaptable plant) and Orychophragmus violaceus (Ov, a karst-adaptable plant) as plant materials, employed a bidirectional nitrogen-isotope-tracing method, and performed the quantification of the contribution of EMP and PPP. We found that bicarbonate and ammonium inhibited glucose metabolism and nitrogen utilization in Bn under simulated karst habitats. On the other hand, it resulted in a shift from EMP to PPP to promote ammonium utilization in Ov under high ammonium stress in karst habitats. Compared with Bn, bicarbonate promoted glucose metabolism and nitrogen utilization in Ov at low ammonium levels, leading to an increase in photosynthesis, the PPP, carbon and nitrogen metabolizing enzyme activities, nitrate/ammonium utilization, and total inorganic nitrogen assimilation capacity. Moreover, bicarbonate significantly reduced the growth inhibition of Ov by high ammonium, resulting in an improved PPP, RCRUBP, and ammonium utilization to maintain growth. Quantifying the relationships between EMP, PPP, NO3-, and NH4+ utilization can aid the accurate analysis of carbon and nitrogen use efficiency changes in plant species. Therefore, it provides a new prospect to optimize the nitrate/ammonium utilization in plants and further reveals the differential responses of inorganic carbon and nitrogen (C-N) metabolism to bicarbonate and variable ammonium in karst habitats.