Purification and Characterization of Bioactive Compounds from Styela clava

The immunomodulatory activity of extract from Styela clava was studied systematically based on activity tracking in vitro in order to find out novel-structured secondary metabolite. The proliferation rates of mouse splenic lymphocytes and peritoneal macrophages were used as screening index, as well as NO release promoting activities. The crude extract (CE) and its different polar fractions from S. clava all exhibited proliferative activity of splenolymphocytes and mouse macrophages, as well as NO release promoting activities, among which petroleum ether fraction (PE) showed the strongest effect. The antioxidant experiment in vitro showed that CE demonstrated antioxidant ability in 1,1-diphenyl-2-picrylhydrazyl (DPPH) system and the beta carotene-linoleic acid system; the activity of ethyl acetate fraction (ET) was much stronger than that of the others. Further isolated by silica gel column chromatography, ET was classified into seven sub-components (E1~E7) listed in the order of activity as E5>E6>E4>E3>E7>E2>E1. Five compounds were separated as (1) cholesteric-7-en-3β-ol, (2) cholesteric-4-en-3β,6β-diol, (3) cholesterol, (4) batilol, and (5) ceramide, among which (1), (2), and (4) were isolated for the first time from S. clava

Purification and Characterization of Bioactive Compounds from Styela clava

The immunomodulatory activity of extract from Styela clava was studied systematically based on activity tracking in vitro in order to find out novel-structured secondary metabolite. The proliferation rates of mouse splenic lymphocytes and peritoneal macrophages were used as screening index, as well as NO release promoting activities. The crude extract (CE) and its different polar fractions from S. clava all exhibited proliferative activity of splenolymphocytes and mouse macrophages, as well as NO release promoting activities, among which petroleum ether fraction (PE) showed the strongest effect. The antioxidant experiment in vitro showed that CE demonstrated antioxidant ability in 1,1-diphenyl-2-picrylhydrazyl (DPPH) system and the beta carotene-linoleic acid system; the activity of ethyl acetate fraction (ET) was much stronger than that of the others. Further isolated by silica gel column chromatography, ET was classified into seven sub-components (E1∼E7) listed in the order of activity as E5 > E6 > E4 > E3 > E7 > E2 > E1. Five compounds were separated as (1) cholesteric-7-en-3 -ol, (2) cholesteric-4-en-3 ,6 -diol, (3) cholesterol, (4) batilol, and (5) ceramide, among which (1), (2), and (4) were isolated for the first time from S. clava

The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance

Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth

Overexpressing of OsAMT1-3, a High Affinity Ammonium Transporter Gene, Modifies Rice Growth and Carbon-Nitrogen Metabolic Status

AMT1-3 encodes the high affinity NH4+ transporter in rice roots and is predominantly expressed under nitrogen starvation. In order to evaluate the effect of AMT1-3 gene on rice growth, nitrogen absorption and metabolism, we generated AMT1-3-overexpressing plants and analyzed the growth phenotype, yield, carbon and nitrogen metabolic status, and gene expression profiles. Although AMT1-3 mRNA accumulated in transgenic plants, these plants displayed significant decreases in growth when compared to the wild-type plants. The nitrogen uptake assay using a 15N tracer revealed poor nitrogen uptake ability in AMT1-3-overexpressing plants. We found significant decreases in AMT1-3-overexpressing plant leaf carbon and nitrogen content accompanied with a higher leaf C/N ratio. Significant changes in soluble proteins and carbohydrates were also observed in AMT1-3-overexpressing plants. In addition, metabolite profile analysis demonstrated significant changes in individual sugars, organic acids and free amino acids. Gene expression analysis revealed distinct expression patterns of genes that participate in carbon and nitrogen metabolism. Additionally, the correlation between the metabolites and gene expression patterns was consistent in AMT1-3-overexpressing plants under both low and high nitrogen growth conditions. Therefore, we hypothesized that the carbon and nitrogen metabolic imbalance caused by AMT1-3 overexpressing attributed to the poor growth and yield of transgenic plants

Overexpressing of OsAMT1-3, a High Affinity Ammonium Transporter Gene, Modifies Rice Growth and Carbon-Nitrogen Metabolic Status

AMT1-3 encodes the high affinity NH4+ transporter in rice roots and is predominantly expressed under nitrogen starvation. In order to evaluate the effect of AMT1-3 gene on rice growth, nitrogen absorption and metabolism, we generated AMT1-3-overexpressing plants and analyzed the growth phenotype, yield, carbon and nitrogen metabolic status, and gene expression profiles. Although AMT1-3 mRNA accumulated in transgenic plants, these plants displayed significant decreases in growth when compared to the wild-type plants. The nitrogen uptake assay using a 15N tracer revealed poor nitrogen uptake ability in AMT1-3-overexpressing plants. We found significant decreases in AMT1-3-overexpressing plant leaf carbon and nitrogen content accompanied with a higher leaf C/N ratio. Significant changes in soluble proteins and carbohydrates were also observed in AMT1-3-overexpressing plants. In addition, metabolite profile analysis demonstrated significant changes in individual sugars, organic acids and free amino acids. Gene expression analysis revealed distinct expression patterns of genes that participate in carbon and nitrogen metabolism. Additionally, the correlation between the metabolites and gene expression patterns was consistent in AMT1-3-overexpressing plants under both low and high nitrogen growth conditions. Therefore, we hypothesized that the carbon and nitrogen metabolic imbalance caused by AMT1-3 overexpressing attributed to the poor growth and yield of transgenic plants

The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance

Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth

Accumulated Expression Level of Cytosolic <i>Glutamine Synthetase 1</i> Gene (<i>OsGS1;1</i> or <i>OsGS1;2</i>) Alter Plant Development and the Carbon-Nitrogen Metabolic Status in Rice

<div><p>Maintaining an appropriate balance of carbon to nitrogen metabolism is essential for rice growth and yield. Glutamine synthetase is a key enzyme for ammonium assimilation. In this study, we systematically analyzed the growth phenotype, carbon-nitrogen metabolic status and gene expression profiles in <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing rice and wildtype plants. Our results revealed that the <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants exhibited a poor plant growth phenotype and yield and decreased carbon/nitrogen ratio in the stem caused by the accumulation of nitrogen in the stem. In addition, the leaf SPAD value and photosynthetic parameters, soluble proteins and carbohydrates varied greatly in the <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants. Furthermore, metabolite profile and gene expression analysis demonstrated significant changes in individual sugars, organic acids and free amino acids, and gene expression patterns in <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants, which also indicated the distinct roles that these two <i>GS1</i> genes played in rice nitrogen metabolism, particularly when sufficient nitrogen was applied in the environment. Thus, the unbalanced carbon-nitrogen metabolic status and poor ability of nitrogen transportation from stem to leaf in <i>GS1;1-</i>, <i>GS1;2</i>-overexpressing plants may explain the poor growth and yield.</p></div

The root length, plant height, root and shoot dry weight in the <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants (OX-<i>GS1;1</i>, OX-<i>GS1;2</i>) and wildtype plants (WT) at the tillering stage (A) and the heading stage (B) under 0×N, 0.1×N, 1×N and 5×N conditions.

<p>Values are the mean ± SD of ten randomly selected plants. a, b, c indicate the significant difference at the level of P = 0.05.</p

The ¹⁵N (¹⁵N%) and total nitrogen content (TN%) in the roots, stems and leaves of the <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants (OX-<i>GS1;1</i>, OX-<i>GS1;2</i>) and wildtype plants (WT) at 1 h, 3 h, 8 h, 1 d and 3 d after NH₄NO₃ in the nutrient solution was replaced with ¹⁵NH₄¹⁵NO₃ during the tillering stage.

<p>Values are the means from six randomly mixed plant materials.</p

The yield and its components in the <i>GS1;1</i>-, <i>GS1;2</i>-overexpressing plants (OX-<i>GS1;1</i>, OX-<i>GS1;2</i>) and wildtype plants (WT) under 0×N, 0.1×N, 1×N, 5×N conditions.

<p>Values are mean ± SD from ten randomly selected plants. a, b, c indicate the significant difference at the level of P = 0.05.</p