Long-term moderate wind induced sediment resuspension meeting phosphorus demand of phytoplankton in the large shallow eutrophic Lake Taihu.

The objective of this study was to investigate the impact of sediment resuspension and phosphorus (P) release on phytoplankton growth under different kinds of wind-wave disturbance conditions in the large and shallow eutrophic Lake Taihu in China. Short-term strong wind (STSW) conditions, long-term moderate wind (LTMW) conditions, and static/calm conditions were investigated. To address this objective, we (1) monitored changes in surface water P composition during field-based sediment resuspension caused by STSW conditions in Lake Taihu, and also conducted (2) a series of laboratory-based sediment resuspension experiments to simulate LTMW and calm conditions. The results showed that under both strong and moderate wind-wave conditions, suspended solids (SS) and total phosphorus (TP) in the water column increased significantly, but total dissolved phosphorus (TDP) and soluble reactive phosphorus (SRP) remained low throughout the experiments, indicating that the P released from sediments mainly existed in particulate forms. In STSW conditions, alkaline phosphatase activity (APA) and enzymatically hydrolysable phosphorus (EHP) increased rapidly, with the peak value occurring following the peak value of wind speed for 1-2 days, and then rapidly decreased after the wind stopped. Under LTMW conditions, APA and EHP increased steadily, and by the end of the laboratory experiments, APA increased by 11 times and EHP increased by 5 times. Chlorophyll a (Chl-a) in LTMW conditions increased significantly, but remained low under STSW conditions, demonstrating that the former type of sediment P release promoted phytoplankton growth more effectively, and the latter type did not. Despite the fact that STSW conditions resulted in the release of more TP, TP settled to the bottom rapidly with SS after the wind stopped, and did not promote algal growth. Under LTMW conditions, suspended particulate P was hydrolyzed to SRP by phosphatase and promoted algae growth. Algal growth in turn secreted more phosphatase and accelerated particulate P regeneration, which may be the main mechanism of sediment bio-available P release that promotes phytoplankton growth in shallow lakes.

Kidney tubular-cell secretion of osteoblast growth factor is increased by kaempferol: a scientific basis for "the kidney controlling the bone" theory of Chinese medicine.

OBJECTIVE: To study, at the cytological level, the basic concept of Chinese medicine that "the Kidney (Shen) controls the bone". METHODS: Kaempferol was isolated form Rhizoma Drynariae (Gu Sui Bu, GSB) and at several concentrations was incubated with opossum kidney (OK) cells, osteoblasts (MC3T3 E1) and human fibroblasts (HF) at cell concentrations of 2×10(4)/mL. Opossum kidney cell-conditioned culture media with kaempferol at 70 nmol/L (70kaeOKM) and without kaempferol (0OKM) were used to stimulate MC3T3 E1 and HF proliferation. The bone morphological protein receptors I and II (BMPR I and II) in OK cells were identified by immune-fluorescence staining and Western blot analysis. RESULTS: Kaempferol was found to increase OK cell growth (P<0.05), but alone did not promote MC3T3 E1 or HF cell proliferation. However, although OKM by itself increased MC3T3 E1 growth by 198% (P<0.01), the 70kaeOKM further increased the growth of these cells by an additional 127% (P<0.01). It indicates that the kidney cell generates a previously unknown osteoblast growth factor (OGF) and kaempferol increases kidney cell secretion of OGF. Neither of these media had any significant effect on HF growth. Kaempferol also was found to increase the level of the BMPR II in OK cells. CONCLUSIONS: This lends strong support to the original idea that the Kidney has a significant influence over bone-formation, as suggested by some long-standing Chinese medical beliefs, kaempferol may also serve to stimulate kidney repair and indirectly stimulate bone formation.

Flavonoid of Drynaria fortunei protects against acute renal failure.

The flavonoid fraction (FF) from Drynaria fortunei was investigated to determine its biological activity expression in three acute renal failure animal models. Guinea pigs received 100 mg/kg of gentamicin (GM group), 100 mg/kg of GM plus 10 mg/kg of FF (GMFF group), 10 mg/kg of FF (FF group) or saline (saline group) intramuscularly for 14 days. The blood urea nitrogen (BUN) and creatinine levels were found to be significantly higher in the GM group (22.70+/-3.84 mg/dL, 0.68+/-0.05 mg/dL) than in the GMFF group (17.10+/-1.04 mg/dL, 0.58+/-0.09 mg/dL), the FF group (17.40+/-1.01 mg/dL, 0.49+/-0.20 mg/dL) and the saline group (17.50+/-1.22 mg/dL, 0.50+/-0.02 mg/dL). Mice were treated once with 6 mg/kg of mercuric chloride, followed by 10 mg/kg of FF or saline. On days 3, 4 and 5, BUN and creatinine levels were found to be significantly higher in the HgCl2-saline group (74.00+/-39.20 mg/dL, 59.30+/-31.20 mg/dL, 74.00+/-37.30 mg/dL and 0.53+/-0.17 mg/dL, 0.48+/-0.15 mg/dL 0.33+/-0.15 mg/dL) than in the HgCl2-FF group (19.50+/-4.90 mg/dL, 43.00+/-26.30 mg/dL, 38.50+/-13.80 mg/dL and 0.23+/-0.05 mg/dL, 0.30+/-0.12 mg/dL, 0.15+/-0.06 mg/dL).After surgery for 5/6-nephrectomy, ten mice received FF at a dose of 10 mg/kg/day and eight received saline for 42 days. The saline group survived for 12-62 days and the FF group survived for 20-320 days. The FF group had a significantly longer survival time than the saline group (p<0.05). Regeneration of kidney tubular cells and significantly enlarged convoluted tubules were noted in the pathology study of the FF group. In conclusion, the present study suggests that FF prevents nephrotoxicity, improves kidney function and promotes kidney primary epithelial tubular cell regeneration.

Flavanoid of Drynaria fortunei protects against gentamicin ototoxicity.

A flavanoid fraction (FF) from Drynaria fortunei, was investigated to see if it has the protective and ameliorative effects against gentamicin (GM) ototoxicity in guinea pigs (n = 36). Eleven (GM-group) animals received GM 100 mg/kg/day. Eleven (GMFF-group) animals received the same dose of GM but 2 days prior were dosed with FF (10 mg/kg/day) for 2 weeks. Seven (S-group) animals received saline and seven (FF-group) animals received the same dose of FF as the GMFF-group. The thresholds of tone-burst auditory evoked response (ABR) at 2 k, 8 k, and 32 k Hz were determined to be as follows: GM-group: 90 dB, 92 dB and 72 dB, GMFF-group: 30 dB, 37 dB and 38 dB, FF-group: 28 dB, 25 dB and 29 dB, S-group: 30 dB, 28 dB and 39 dB. The GM-group had a significantly higher hearing threshold than the other groups (p < 0.05). The GMFF- and FF-groups had hearing thresholds similar to the S-groups (p > 0.1). Repair of damaged hair cells was observed histologically. The percentage of the damaged outer hair cells (OHC) and inner hair cells (IHC) were determined to be as follows: GM-group: 43% and 20%, GMFF-group: 20% and 2%, FF-group: 9% and 2% and S-group: 4% and 1%. The GMFF-group showed less damage to the OHC (p > 0.05) and significantly less damage to the IHC (p < 0.05) than the GM-group. FF did not change the antimicrobial activity of GM and it did not show any intrinsic antibacterial effect. FF did not affect the kinetics of GM during the course of the experiment.