Antiobesity Effect of Flaxseed Polysaccharide via Inducing Satiety due to Leptin Resistance Removal and Promoting Lipid Metabolism through the AMP-Activated Protein Kinase (AMPK) Signaling Pathway.

Obesity is a metabolic syndrome worldwide that causes many chronic diseases. Recently, we found an antiobesity effect of flaxseed polysaccharide (FP), but the mechanism remains to be elucidated. In this study, rats were first induced to develop obesity by being fed a high-fat diet. The obese rats were then fed a control diet, AIN-93M (group HFD), or a 10% FP diet (group FPD). The body weight, body fat, adipose tissue and liver sections, serous total triglycerides, levels of fasting blood glucose in serum, serous insulin, inflammatory cytokines in serum, and serous proteins within the leptin-neuropeptide Y (NPY) and AMP-activated protein kinase (AMPK) signaling pathway were determined and analyzed. FP intervention significantly reduced body weight and abdominal fat from 530 ± 16 g and 2.15% ± 0.30% in group HFD to 478 ± 10 g and 1.38% ± 0.48% in group FPD, respectively. This effect was achieved by removing leptin resistance possibly by inhibiting inflammation and recovering satiety through the significant downregulation of NPY and the upregulation of glucagon-like peptide 1. Adiponectin was then significantly upregulated probably via the gut-brain axis and further activated the AMPK signaling pathway to improve lipid metabolism including the improvement of lipolysis and fatty acid oxidation and the suppression of lipogenesis. This is the first report of the proposed antiobesity mechanism of FP, thereby providing a comprehensive understanding of nonstarch polysaccharides and obesity.

Inhibition of five natural products from Chinese herbs on the growth of Chattonella marina.

The effects of five natural products from Chinese herbs including evodiamine, curcumin, 4-methoxysalicylaldehyde, esculin hydrate, and gramine on the growth of Chattonella marina, one of the most noxious red tide algae, were observed. Among them, gramine exhibited the highest inhibitory rate with LC50, 96h of 0.51 mg/l. After exposure to gramine, the activities of superoxide dismutase (SOD) and catalase (CAT), and content of malondialdehyde (MDA) increased in C. marina, suggesting that gramine could induce microalgae oxidative stress. In addition, chlorophyll a and the maximum quantum yield of photosynthesis (Fv/Fm) decreased following exposure to gramine, indicating the inhibition of photosynthesis activity in the microalgae. Combined with the fast inhibition against the algal cells and environmentally friendly character of gramine, we proposed that gramine might be a potential algaecide against marine harmful algae and that the oxidative damage and photosynthesis inhibition might be responsible for the toxicity of gramine on harmful algae.

Examination of metabolic responses to phosphorus limitation via proteomic analyses in the marine diatom Phaeodactylum tricornutum.

Phosphorus (P) is an essential macronutrient for the survival of marine phytoplankton. In the present study, phytoplankton response to phosphorus limitation was studied by proteomic profiling in diatom Phaeodactylum tricornutum in both cellular and molecular levels. A total of 42 non-redundant proteins were identified, among which 8 proteins were found to be upregulated and 34 proteins were downregulated. The results also showed that the proteins associated with inorganic phosphate uptake were downregulated, whereas the proteins involved in organic phosphorus uptake such as alkaline phosphatase were upregulated. The proteins involved in metabolic responses such as protein degradation, lipid accumulation and photorespiration were upregulated whereas energy metabolism, photosynthesis, amino acid and nucleic acid metabolism tend to be downregulated. Overall our results showed the changes in protein levels of P. tricornutum during phosphorus stress. This study preludes for understanding the role of phosphorous in marine biogeochemical cycles and phytoplankton response to phosphorous scarcity in ocean. It also provides insight into the succession of phytoplankton community, providing scientific basis for elucidating the mechanism of algal blooms.

Systems-level analysis of the metabolic responses of the diatom Phaeodactylum tricornutum to phosphorus stress.

Phosphorus is an important macronutrient. To understand the molecular and cellular responses to phosphorus stress better, transcriptome profiling in combination with biochemical investigations was conducted in the model diatom Phaeodactylum tricornutum. Out of 10 402 predicted genes, 2491 and 405 genes were significantly upregulated or downregulated respectively. Unsurprisingly, genes associated with phosphate uptake were upregulated, such as the phosphate transporters and alkaline phosphatases. Genes encoding stress-shock proteins were accordingly upregulated, including genes associated with stress-responsive proteins, signal transduction and secondary metabolism. Additionally, genes related to protein translation, carbon fixation, glycolysis and the citric acid cycle were also upregulated. Genes associated with gene transcription were downregulated, thereby resulting in the upregulation of translation to compensate for the limited supply of messenger RNA. The downregulation of genes related to ß-oxidation could contribute to the accumulation of fatty acids. Accordingly, triacylglycerols, which are important for energy storage, were determined to increase by 1.65-fold. Intracellular membranes, other than chloroplast membranes, tended to be dispersed; this finding was in accordance with the increased transcription of a total of 11 genes encoding putative phospholipases. Taken together, this work revealed the coordination of multiple metabolic pathways and certain key genes in the adaptation of P. tricornutum to phosphorus stress.

[Effects of some membrane lipids on the hemolysis induced by hemolytic toxin from Karenia mikimotoi].

OBJECTIVE: To explore the effects of some membrane lipids on the hemolysis induced by hemolytic toxin from Karenia mikimotoi. METHODS: Effects of exogenous membrane lipids such as lecithin, sphingomyelin, L-alpha-phosphatidic acid,cholesterol and gangliosides on the hemolysis induced by the hemolytic toxin were observed. The sensitivities of some erythrocytes from different animals such as rabbit, rat and fish to the hemolytic toxin were evaluated. The total gangliosides in different erythrocytes membrane were detected by colorimetry. RESULTS: Only gangliosides significantly inhibited the hemolysis of the hemolytic toxin from K. mikimotoi (P <0.05). Hemolytic percentages decreased to 16.05% after 10 min addition of ganglioside, while those of control were 35.65%. The rabbit red blood cell was the most sensitive to the hemolytic toxin. The hemolytic percentages of rabbit erythrocyte were higher than those of rat (P < 0.05) and fish (P < 0.01). The amounts of lipid-bind sialic acid (LBSA) on frozen dried membrane of rabbit were 672.08 microg/g,and were higher than those of rat (585.97 microg/g) (P < 0.05) and that of fish (431.52 microg/g) (P < 0.01). CONCLUSION: Exogenous gangliosides could have a potent inhibition on the hemolysis induced by hemolytic toxin from K. mikimotoi. There was a significant correlation between the sensitivities of different erythrocytes to the hemolytic toxin and the amount of ganglioside on different erythrocytes membrane.

Inhibition of the growth of Alexandrium tamarense by algicidal substances in Chinese fir (Cunninghamia lanceolata).

The wood sawdust from Chinese fir (Cunninghamia lanceolata) exhibited stronger inhibition on the growth of Alexandrium tamarense than those from alder (Alnus cremastogyne), pine (Pinus massoniana), birch (Betula alnoides) and sapele (Entandrophragma cylindricum). The water extract, acetone-water extract and essential oil from fir sawdust were all shown to inhibit the growth of A. tamarense. The inhibition of fir essential oil was the strongest among all the above wood sources while the half effective concentration was only 0.65 mg/L. These results suggested that the fir essential oil may play an important role in the algicidal effect of Chinese fir.

[Inhibitory effects and chemical basis of cornstalk on the growth of Alexandrium tamarense].

To provide more information on new algaecide with high efficiency, ecological safety and selectivity, effects of corn stem and leaves on the growth of Alexandrium tamarense were observed. The roles of microorganism in the inhibition were assessed. The inhibitory activities of different solvent extracts from the corn leaves were discussed and the potential antialgal chemicals in corn leaves were analyzed by GC-MS. Cornstalk is shown to have distinctly inhibitory effect on A. tamarense, and the inhibition of corn leaves is stronger than that of the corn stem. 0.5 g/L of the corn leaves inhibit A. tamarense remarkably in cell density of 1.69 x 10(6) cells/L. There are little differences in antialgal action between asepsis leaves and rude leaves, suggesting that some antialgal compounds from leaves may be responsible for the inhibition and that microorganisms from leaves have little effect on the inhibition. The petroleum ether and dichloromethane extracts from corn leaves are shown to have stranger inhibition on A. tamarense than ethyl acetate and n-butanol extracts. CC-MS shows that extracts with high inhibitory activities contain many fatty acids such as linoleic acid, linolenic acid, and palmitic acid, etc. These results suggest that corn leaves have some inhibitory effect on A. tamarense and fatty acids may be responsible for the inhibition.

[Inhibitory effects and chemical basis of Eucalyptus orelliana wood meals on the growth of Alexandrium tamarense].

To provide information on the screen of newly and efficient algaecides in controlling harmful algal blooms (HABs), the effects of wood meals from Eucalyptus torelliana, Eucalyptus urophylla, Eucalyptus exserta on the growth of Alexandrium tamarense were observed and the chemical basis of the antialgal effect was discussed. The results show that the inhibitory activities of the three wood meals are different, and E. torelliana wood meals have the highest inhibitory activity. There are little differences in antialgal action between asepsis and rude wood meals, suggesting that some antialgal compounds from wood meals may be responsible for the inhibition and that microorganisms from wood meals have little effect on the inhibition. The acetone-water extract from E. torelliana wood meals is shown to have stronger inhibition on A. tamarense than that from ethyl acetate, water and methanol extracts. The acetone-water extract from E. torelliana wood meals was further divided into extract A, B, C and D and the inhibitory activities were compared. The extract D is shown to have highest inhibitory activity. 3 mg/L of the extract appears 81% inhibition rate to A. tamarense in the 3rd day. GC-MS show that extract D contains mostly ketones such as 4-hydroxy-3,5,6-trimethyl-4-(3-oxo-1-butenyl)-2-cyclohexen-1-one and 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone. These results suggest that wood meals from E. torelliana had certain inhibitory effect on A. tamarense, and that ketones may be responsible for the inhibition.

[Effects of different phosphorus sources on the growth and toxin production of Prorocentrum lima].

To explore the nutrient properties of Prorocentrum lima and biosynthesis mechanism of diarrhetic shellfish poison (DSP), the growth and activities of alkaline phosphatase of Prorocentrum lima were observed under different phosphorus sources. DSP productions were also analyzed. The maximum growth rate (micro(max)) was slightly lower under beta-sodium glycerophosphate than those under NaH2PO4 and ATP as phosphorus sources, respectively. The maximum biomass (X) under ATP was higher than those under NaH2PO4 and beta-sodium glycerophosphate as the phosphorus sources, respectively. When the concentration of NaH2PO4 was below 2 micromol/L, the activity of alkaline phosphatase increased significantly. However, the activities were much low in the all treatments when beta-sodium glycerophosphate used as phosphorus source, whereas the activities increased with the concentration of ATP when ATP used as phosphorus source. The level of okadaic acid (OA) in Prorocentrum lima at the stationary phase under beta-sodium glycerophosphate was higher than those under NaH2PO4 and ATP. These suggested that beta-sodium glycerophosphate could be utilized directly by Prorocentrum lima with lower efficiency; ATP could induce alkaline phosphatase to produce inorganic phosphate for algae. DSP production in Prorocentrum lima were different under various phosphate sources, beta-sodium glycerophosphate enhanced production of DSP. The difference in DSP production might be related with the physiological state of Prorocentrum lima.

[Effect of the long-term intake of yttrium in drinking water on trace elements in F1 generation mice].

The effects of the long-term intake of yttrium on trace elements in tissues and yttrium in brain of F1 generation mice were studied so as to elucidate some physiological function of the rare earths. The mice were fed with Y3+ (0, 23.25 mg/L, 2325.00 mg/L) dissolved water at different levels for seven months. The level of trace elements such as Cu, Cd, Pb and Y in brain and Se in brain, liver, spleen and kidney of F1 generation mice were measured by ICP-MS and atom fluorescent method. The results showed that, compared with control mice, significant changes in content of Se (P < 0.05) in spleen and Y (P < 0.05) in brain were observed, but no changes were found in content of Pb, Cd, and Cu in brain for the high dose group, and an increase was detected in content of Se(P < 0.05) in spleen for the low dose group, suggesting that long-term intake of Y3+ might enhance the absorption of Se in some tissue that might be one of the biological effect of rare earth and, Y3+ might enter young mammalian brain.