Identification of candidate genes and residues for improving nitrogen use efficiency in the N-sensitive medicinal plant Panax notoginseng.

BACKGROUND: Nitrogen (N) metabolism-related key genes and conserved amino acid sites in key enzymes play a crucial role in improving N use efficiency (NUE) under N stress. However, it is not clearly known about the molecular mechanism of N deficiency-induced improvement of NUE in the N-sensitive rhizomatous medicinal plant Panax notoginseng (Burk.) F. H. Chen. To explore the potential regulatory mechanism, the transcriptome and proteome were analyzed and the three-dimensional (3D) information and molecular docking models of key genes were compared in the roots of P. notoginseng grown under N regimes. RESULTS: Total N uptake and the proportion of N distribution to roots were significantly reduced, but the NUE, N use efficiency in biomass production (NUEb), the recovery of N fertilizer (RNF) and the proportion of N distribution to shoot were increased in the N0-treated (without N addition) plants. The expression of N uptake- and transport-related genes NPF1.2, NRT2.4, NPF8.1, NPF4.6, AVP, proteins AMT and NRT2 were obviously up-regulated in the N0-grown plants. Meanwhile, the expression of CIPK23, PLC2, NLP6, TCP20, and BT1 related to the nitrate signal-sensing and transduction were up-regulated under the N0 condition. Glutamine synthetase (GS) activity was decreased in the N-deficient plants, while the activity of glutamate dehydrogenase (GDH) increased. The expression of genes GS1-1 and GDH1, and proteins GDH1 and GDH2 were up-regulated in the N0-grown plants, there was a significantly positive correlation between the expression of protein GDH1 and of gene GDH1. Glu192, Glu199 and Glu400 in PnGS1 and PnGDH1were the key amino acid residues that affect the NUE and lead to the differences in GDH enzyme activity. The 3D structure, docking model, and residues of Solanum tuberosum and P. notoginseng was similar. CONCLUSIONS: N deficiency might promote the expression of key genes for N uptake (genes NPF8.1, NPF4.6, AMT, AVP and NRT2), transport (NPF1.2 and NRT2.4), assimilation (proteins GS1 and GDH1), signaling and transduction (genes CIPK23, PLC2, NLP6, TCP20, and BT1) to enhance NUE in the rhizomatous species. N deficiency might induce Glu192, Glu199 and Glu400 to improve the biological activity of GS1 and GDH, this has been hypothesized to be the main reason for the enhanced ability of N assimilation in N-deficient rhizomatous species. The key genes and residues involved in improving NUE provide excellent candidates for the breeding of medicinal plants.

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.

Structural stability and electronic and mechanical properties of nitrogen- and boron-doped fluorinated diamane.

In this work, the structural, electronic and mechanical properties of fluorinated diamane (F-diamane) with N and B dopants are systemically investigated using first-principles calculation. The N atom tends to stay in the external substituted site without F saturation, while the B-doped structure of the substituted external site with F saturation is the most stable. Ab initio molecular dynamics simulations confirm the thermal stability. The band structures of stable doped structures are similar to that of pristine F-diamane, due to the slight contribution of the dopant to the band edges. In addition, after the introduction of the B dopant, the formation energy reduces, and the transition barrier of graphene bilayers into diamane is smaller, indicating the feasibility of graphene bilayer fluoridation. Furthermore, we find that these doped structures have mechanical stability with isotropic elastic constants, Young's modulus, shear modulus and Poisson's ratio. Our work would promote the synthesis and development of two-dimensional diamane.

Structural and electronic properties of pristine and hydrogen-terminated c-BN(100) surfaces.

Semiconductor surfaces are crucially important for electronics, but it is difficult to directly image their surface structures. In this work, the surface structures and electronic properties of pristine and H-terminated c-BN(100) surfaces are predicted by first principles calculation. It is found that the surfaces with reconstructed dimers and staggered dimers are thermally and dynamically stable. When the surface N and B atoms are saturated with the virtual H of 0.5 e and 1.5 e, the surface states near Fermi level are nearly removed, and have the wide bandgaps. Meanwhile, after surface hydrogenation, the electron affinity value changes from positive to negative. Our findings could provide a theoretical guidance for designing c-BN-based electronic devices.

Intravenous thrombolysis with alteplase in the treatment of acute cerebral infarction.

Objectives: To compare the efficacy and safety of intravenous thrombolysis with alteplase and intravenous thrombolysis with urokinase for patients with acute cerebral infarction. Methods: This prospective study included 140 patients with acute cerebral infarction who were admitted to our hospital between June 2018 and June 2019. They were randomly divided into two groups. The control group (70 cases) was treated with urokinase intravenous thrombolysis, and the observation group (70 cases) was given alteplase intravenous thrombolytic therapy. The treatment efficacy and safety of the two groups were compared. Results: The total effective rate of the observation group was 95.7%, and that of the control group was 78.6%, i.e., the total effective rate of the observation group was significantly superior to the that of the control group (P < 0.05). After treatment, the observation group had significantly lower National Institutes of Health Stroke Scale (NIHSS) score and significantly higher mini-mental state examination (MMSE) score than the control group; the difference was statistically significant (P<0.05). After treatment, the levels of inflammatory factors of both groups significantly decreased compared to before treatment, and the decrease in the observation group was larger than that in the control group (P<0.05). The levels of serum homocysteine (Hcy) and monocyte chemoattractant protein-1 (MCP-1) in the observation group were significantly lower than those in the control group after treatment, and the differences were statistically significant (P<0.05). The incidence of hemorrhagic adverse reaction in the observation group was lower than that in the control group (P<0.05). Conclusion: In the treatment of acute cerebral infarction, ccompared with urokinase, alteplase can further relieve cognitive impairment and promote the recovery of nerve function through inhibiting levels of inflammatory factors and levels of serum Hcy and MCP-1.

Clinical observation of mild hypothermia combined with intravenous thrombolysis in treating patients with acute cerebral infarction.

OBJECTIVES: To investigate the clinical effect of mild hypothermia combined with intravenous thrombolysis in the treatment of acute cerebral infarction. METHODS: Eighty-eight patients with acute cerebral infarction in Binzhou People's Hospital between May 2018 and August 2019 were randomly selected and divided into a control group and an observation group according to the random number table method, with 44 patients in each group. The control group was given intravenous thrombolysis; the observation group was treated with mild hypothermia (30-35°C) in addition to intravenous thrombolytic thrombolysis. The clinical efficacy, incidence of complications, oxidative stress indexes, inflammatory factor level, neurological function, and mental state of the two groups before and after treatment were compared. RESULTS: The clinical efficacy of the observation group was significantly better than that of the control group, and the difference was statistically significant (P<0.05). There was no significant difference in the levels of oxidative stress indexes and inflammatory factors between the two groups before treatment (P<0.05). After treatment, the levels of oxidative stress indexes and inflammatory factors of the two groups significantly improved, and the improvement of the observation group was better than that of the control group; the differences were statistically significant (P<0.05). There was no significant difference in the neurological function and mental state between the two groups before treatment (P<0.05). After treatment, the neurological function and mental state of the two groups significantly improved, and the improvement of the observation group was better than that of the control group; the differences were statistically significant (P<0.05). There was no significant difference in the incidence of complications and mortality between the two groups (P>0.05). CONCLUSION: Thrombolytic therapy combined with mild hypothermia has a good efficacy in the treatment of acute cerebral infarction. The therapy can improve the neurological function of patients with acute cerebral infarction by significantly improving the oxidative stress index and relieving the inflammatory reaction. Its efficacy is better than single thrombolytic therapy.

Pioglitazone is an effective treatment for patients with post-stroke depression combined with type 2 diabetes mellitus.

The antidepressive effects of the antidiabetic medicine, pioglitazone, were recently reported in several studies. These effects may ameliorate the depressive symptoms of patients with post-stroke depression (PSD). The present study aimed to evaluate the antidepressive effect of pioglitazone in patients with PSD combined with type 2 diabetes. A total of 118 consecutive patients with stroke who had depression were studied for an average of 3 months. The Diagnostic and Statistical Manual of Mental Disorders (fourth edition) was used to assess whether a patient was depressed or not. The severity of depression was evaluated by the Hamilton depression rating scale (HAMD). In accordance with their HAMD scores, the 118 patients were divided into a severe depression group (n=40) and a mild and moderate (MM) depression group (n=78). These subjects were then divided into pioglitazone [30 mg once daily (qd)] and metformin (0.5 g twice daily) subgroups. All patients were given fluoxetine (20 mg qd). Follow-up evaluations, which included HAMD scores, activities of daily living (ADL) scores, fasting blood glucose (FBG) levels and fasting insulin (FINS) levels, were conducted on the first and third month following the beginning of the treatment. In the MM depression group, the HAMD score in the pioglitazone subgroup was lower than that in the metformin subgroup following treatment for 1 or 3 months. In the severe depression group, the HAMD score in the pioglitazone subgroup was lower than that in the metformin subgroup following 3 months of treatment. The FINS levels of the pioglitazone subgroup gradually decreased in the 3 months of treatment. No noticeable improvement was observed in the ADL scores and FBG values. In conclusion, the results of the current study demonstrate that pioglitazone effectively decreased HAMD scores and FINS values in patients with PSD, suggesting that pioglitazone may be useful for the treatment of patients with PSD combined with type 2 diabetes.