Characterization of internal phosphorus loading in the sediment of a large eutrophic lake (Lake Taihu, China).

Lake Taihu suffers from severe algal blooms every year, which is attributed primarily to the release of sediment phosphorus (P), namely the internal P loading. However, the overall internal P loading and the P hotspots in sediment have not been fully studied. This paper presents several methods, including sequential P extraction, the use of diffusive gradient in thin film (DGT), and intact core incubation to give a detailed investigation of sediment internal P loading as well as its roles in algal dominated zones (ADZs) and grass dominated zones (GDZs) in Lake Taihu. Sediment microbial composition was also analyzed to investigate its relationship with P fractions. The results indicate that the total P and the mobile P fraction in the ADZ sediments are generally higher than those of the GDZ sediments. The percentage of sediment mobile P to TP is similar to the mobile P in their distributions. In contrast, calcium bound P accounts for most of the TP in GDZ, while mobile P contributes the most to TP in ADZ. Overall, sediment can release 256 tons of TP and 217 tons of soluble reactive phosphorus (SRP) over a period of six months in the warmer seasons. Similarly, a high concentration of DGT-measured P was observed in ADZs that are recognized as P hotspots in Lake Taihu. Sediments in ADZ and GDZ was dominated by the bacteria Firmicutes and Proteobacteria, respectively and which were closely related with mobile P and calcium bound P in sediment, respectively. GZD seems to be able to retain more P in sediments, thereby reducing its contribution to of internal P loading. These results indicate that the difference in sediment composition between ADZ and GDZ affects their roles in sediment internal P loading, therefore, different management strategies should be used to combat sediment internal P loads in the two zones.

Phosphorus internal loading and sediment diagenesis in a large eutrophic lake (Lake Chaohu, China).

Sediment phosphorus (P) release and retention are important in controlling whole-system P dynamics and budget in eutrophic lakes. Here we combine short- (seasonal) and long-term (years to decades) studies to quantify the internal P loading and P release potential in the sediments of Lake Chaohu and explore their controlling mechanisms. In the west region of the lake, short-term P diffusive fluxes ranged from 0.2 mg/m2·d-1 to 6.69 mg/m2·d-1 (averaged 2.76 mg/m2·d-1) and long-term net P release ranged from 2.25 mg/m2·d-1 to 8.94 mg/m2·d-1 (averaged 5.34 mg/m2·d-1); in the east region, short-term P diffusive fluxes varied from 0.73 mg/m2·d-1 to 1.76 mg/m2·d-1 (averaged 1.05 mg/m2·d-1) and long-term P release ranged from 0.13 mg/m2·d-1 to 4.15 mg/m2·d-1 (averaged 1.3 mg/m2·d-1). Both short- and long-term P releases were in the same order of magnitudes as the external P inputs (3.56 mg/m2·d-1). Comparison of the long-term and short-term sediment P release indicates that while the high summer P release in the east might only represent a snapshot value, the sediments in the west contribute to large P release for years or even decades, impeding water quality recovery under lake management. Mobilization of surface sediment legacy P accounted for 81% of short-term P release. The long-term release was dominated by remobilization of iron bond P (BD-P) (average 52.1%) at all sites, while Aluminium-bound P (NaOH-rP) exhibited partly reactive and potentially mobile, releasing P to the water column in most sites in the west. Our study demonstrates the importance of sediments as P sources in lake Chaohu. The combination of short- and long-term P release studies can help understand the roles of sediments in regulating the water quality and eutrophication.

Benthic invaders control the phosphorus cycle in the world's largest freshwater ecosystem.

The productivity of aquatic ecosystems depends on the supply of limiting nutrients. The invasion of the Laurentian Great Lakes, the world's largest freshwater ecosystem, by dreissenid (zebra and quagga) mussels has dramatically altered the ecology of these lakes. A key open question is how dreissenids affect the cycling of phosphorus (P), the nutrient that limits productivity in the Great Lakes. We show that a single species, the quagga mussel, is now the primary regulator of P cycling in the lower four Great Lakes. By virtue of their enormous biomass, quagga mussels sequester large quantities of P in their tissues and dramatically intensify benthic P exchanges. Mass balance analysis reveals a previously unrecognized sensitivity of the Great Lakes ecosystem, where P availability is now regulated by the dynamics of mussel populations while the role of the external inputs of phosphorus is suppressed. Our results show that a single invasive species can have dramatic consequences for geochemical cycles even in the world's largest aquatic ecosystems. The ongoing spread of dreissenids across a multitude of lakes in North America and Europe is likely to affect carbon and nutrient cycling in these systems for many decades, with important implications for water quality management.

Dynamic polyphosphate metabolism in cyanobacteria responding to phosphorus availability.

Despite the crucial role of polyphosphate (polyP) in aquatic environments, its metabolism in cyanobacteria responding to nutrients is poorly understood. We investigate polyP in three cyanobacteria species, specifically unicellular picocyanobacteria, under various nutritional conditions. Our experiments show that the accumulation of polyP in cyanobacteria is strongly dynamic, depending on phosphate levels and growth stages. 'Overplus' uptake of phosphorus (P) during the lag phase leads to the rapid accumulation of polyP, followed by lower polyP quotas during the exponential growth stage as a result of competing 'luxury' P uptake and polyP utilization to support rapid cell division. Cyanobacteria are capable of P deficiency responses that preferentially maintain polyP. However, preferential utilization of polyP occurs under severe P stress, suggesting the crucial role of polyP as P reserve to support cellular survival. Strong variability was observed among different species of cyanobacteria in their ability to accumulate polyP, and likely in the threshold P levels at which preferential polyP degradation occurs. This suggests that some cyanobacteria may be more adaptive to P-stressed or P-fluctuating conditions. Our results explain and provide important insights into the variability of polyP observed in aquatic environments where picocyanobacteria are the dominant primary producers.

[Effects of Tongnao Huoluo acupuncture therapy on Caspase-3 and Bcl-2 of rats with acute cerebral infarction].

OBJECTIVE: To evaluate effects of Tongnao Huoluo acupuncture therapy (THAT) on Bcl-2 and Caspase-3 rats with acute cerebral infarction (ACI). METHODS: Totally 264 SD rats were randomly divided into 5 groups, i.e. the THAT group (n =72), the thrombolysis group (n =72), the body acupuncture group (n =72), the ischemia control group (n =24), and the sham-operation group (n =24). Successfully modeled rats were recruited in all groups except the sham-operation group. Rats in the THAT group, the thrombolysis group, and the body acupuncture group were divided into 3 subgroups according to the disease occurrence time, i.e., < or = 1.5 h THAT group, 1.5+ -2 h THAT group, and 2+ -3 h THAT group. The neuroethological scores were assessed at 6, 24, and 72 h after treatment. The expressions of Bcl-2 and Caspase-3 were detected using immunohistochemical staining at 24 and 72 h respectively. RESULTS: In aspect of improving scores of neurological functions: At 6 h after treatment within 2 h after the disease occurrence, the neuroethological scores were lowered more obviously in the thrombolysis group than in the THAT group (P <0.05). There was statistical difference at 24 and 72 h within 2 - 3 h after the,disease occurrence between the THAT group and the thrombolysis group (P <0.05). Compared with before treatment, there was statistical difference at 24 and 72 h within 3 h after the disease occurrence (P <0. 05, P <0.01). In aspect of lowering the expression of Caspase-3 and elevating the expression of Bcl-2: There was statistical difference in lowering the expression of Caspase-3 and elevating the expression of Bcl-2 between the THAT group and the thrombolysis group at 72 h within 2 -3 after the disease occurrence (P <0.05, P < 0.01). CONCLUSION: THAT showed favorable effects in lowering neuroethological scores, lowering expression of Caspase-3, and elevating the expression of Bcl-2 of ACI rats.

[Impacts of tongnao huoluo acupuncture therapy on BI and NIHSS of patients with acute cerebral infarction].

OBJECTIVE: To evaluate the effect of Tongnao Huoluo Acupuncture (THA) therapy on acute cerebral infarction (ACI). METHODS: Adopting multi-centered, randomized and controlled method, 397 ACI patients from 10 hospitals subjected to the study were treated according to the initiating time (IT) of disease during hospitalization: the 138 patients of stage-1 with IT < or =6 h, were randomly assigned to three groups, treated respectively with THA (Group A), thrombolysis with urokinase (Group B) and Batroxobin (Group C); the 140 patients of stage-2 with IT within 6-48 h, and 119 patients of stage-3 with IT within 48 h-14 d were randomly assigned to three groups, treated respectively with THA (Group D) body acupuncture (Group E), and conventional treatment (Group F). Therapeutic effect was evaluated by NIHSS scores estimated at the day 1, 3, 7, 14, 28 and 90 of treatment, and the Barthel Index (BI) measured at day 14, 28 and 90. RESULTS: Effect in Group A was insignificantly different from that in Group B (P > 0.05), but was different from that in Group C significantly (P < 0.01). At day 90, the percentage of patients with high BI (HBI%, patients with BI >95%) was insignificantly different in Group A vs. B (P > 0.05), but was significantly different in Group A vs. C (P < 0.01). Comparisons between Group D, E and F showed that the therapeutic effect in Group D was equivalent to that in Group E (P < 0.05), but better than that in Group F (P < 0.01), and HBI% in Group D was superior than that in the other two groups (P < 0.01). CONCLUSIONS: THA therapy shows favorable effects in reducing the crippling rate and improving the living capacity of ACI patients.

A genome-wide survey of maize lipid-related genes: candidate genes mining, digital gene expression profiling and co-location with QTL for maize kernel oil.

Lipids play an important role in plants due to their abundance and their extensive participation in many metabolic processes. Genes involved in lipid metabolism have been extensively studied in Arabidopsis and other plant species. In this study, a total of 1003 maize lipid-related genes were cloned and annotated, including 42 genes with experimental validation, 732 genes with full-length cDNA and protein sequences in public databases and 229 newly cloned genes. Ninety-seven maize lipid-related genes with tissue-preferential expression were discovered by in silico gene expression profiling based on 1984483 maize Expressed Sequence Tags collected from 182 cDNA libraries. Meanwhile, 70 QTL clusters for maize kernel oil were identified, covering 34.5% of the maize genome. Fifty-nine (84%) QTL clusters co-located with at least one lipid-related gene, and the total number of these genes amounted to 147. Interestingly, thirteen genes with kernel-preferential expression profiles fell within QTL clusters for maize kernel oil content. All the maize lipid-related genes identified here may provide good targets for maize kernel oil QTL cloning and thus help us to better understand the molecular mechanism of maize kernel oil accumulation.

[Clinical observation on effect of tongnao huoluo acupuncture therapy in treating acute cerebral infarction at ultra-early or acute stage].

OBJECTIVE: To evaluate the efficacy and safety of Tongnao Huoluo acupuncture (TNHLA) therapy in treating acute cerebral infarction at ultra-early stage (within 6 hrs after attack) or acute stage (within 6-48 hrs after attack). METHODS: The effect of TNHLA in the two stages was observed separately (treated group) and compared with the effect treated with immediate thrombolysis by intravenously given urokinase 12 million units in ultra-early stage or simple body acupuncture in acute stage (control group), and with those treated with intravenous dripping of normal saline (placebo group). In the meantime, all groups treated with low molecular dextran injection for 14 days, cytidine diphosphate choline and entric soluble aspirin for 28 days. RESULTS: Effect of TNHLA in the treated group was insignificantly different to that after thrombolysis of the control group in the ultra-early stage, but significantly higher than that of body acupuncture in acute stage. The intracranial hemorrhage rates in the treated, control, and placebo group were 3.3%, 4.0%, and 8.0% respectively. CONCLUSION: TNHLA is effective and safe in treating acute cerebral infarction at ultra-early stage or acute stage.