Bacterial communities in sediments of the shallow Lake Dongping in China

AIMS

The purpose of this study was to discuss how the environmental inputs and anthropogenic activities impact bacterial communities in the sediments of a shallow, eutrophic and temperate freshwater lake.

METHODS AND RESULTS

Sediment cores were collected from Lake Dongping, located in Taian, Shandong, China. All samples were processed within 4 h of collection. Total nitrogen, total phosphorus (TP), total organic carbon, ammonium nitrogen and nitrate nitrogen content of samples were measured by Kjeldahl determination, sulphuric acid-perchloric acid digestion and molybdenum blue colorimetry, potassium dichromate titration, Nessler's reagent colorimetric and the phenol disulphonic acid colorimetric method, respectively. Seasonal and temporal diversity of sediment bacterial communities at six stations in Lake Dongping were investigated using molecular approaches (terminal restriction fragment length polymorphism and 16S rDNA clone libraries). Noticeable seasonal and temporal variations were observed in bacterial diversity and composition at all six stations. Sediment bacterial communities in Lake Dongping belonged to 16 phyla: Proteobacteria (including α-Proteobacteria, β-Proteobacteria, δ-Proteobacteria, ε-Proteobacteria, γ-Proteobacteria), Acidobacteria, Planctomycetes, Bacteroidetes, Firmicutes, Verrucomicrobia, Nitrospira, Chloroflexi, Gemmatimonadetes, Chlorobi, Cyanobacteria, Deferribacteres, Actinobacteria, OP8, Spirochaetes and OP11. Members of β-, δ- and γ-Proteobacterial sequences were predominant in 11 of 12 clone libraries derived from sediment samples. Sediment samples collected at stations 1 and 4 in July had the greatest bacterial diversity while those collected at station 2 in October had the least diversity. TP concentration was significantly correlated with the distribution of bacterial communities.

CONCLUSIONS

Our results suggested that different environmental nutrient inputs contribute to seasonal and temporal variations of chemical features and bacterial communities in sediments of Lake Dongping. TP concentration was significantly correlated with the distribution of bacterial communities.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study has an important implication for the optimization of integrated ecosystem assessment of shallow temperate freshwater lake and provides interesting information for the subsequent of the ecosystem.

Vitamin D deficiency as marker for disease activity and damage in systemic lupus erythematosus: a comparison with anti-dsDNA and anti-C1q

Objectives: To study the sensitivity and specificity of vitamin D deficiency for predicting disease activity and damage of systemic lupus erythematosus (SLE) in comparison with anti-dsDNA and anti-C1q. Methods: Consecutive patients who fulfilled four or more ACR criteria for SLE were studied. Levels of 25-hydroxyvitamin D3, anti-C1q, anti-dsDNA and complement levels were measured. Relationship among these markers, concurrent disease activity and damage scores of SLE was studied by Spearman's rank correlation method. Results: In total, 290 SLE patients were studied (95% women; mean age 38.9 ± 13.1 years; SLE duration 7.7 ± 6.7 years). Clinical or serological lupus activity (SLEDAI ≥ 1) was present in 225 (78%) patients. Vitamin D deficiency (< 15 ng/ml) was detected in 78 (27%) patients. Levels of 25-hydroxyvitamin D3 correlated inversely with the clinical SLE disease activity score (Rho = −0.26; p < 0.001). A negative correlation was also observed between 25-hydroxyvitamin D3 and anti-dsDNA levels (Rho = −0.13; p = 0.02), or anti-C1q (Rho = −0.14; p = 0.02). However, there was no significant relationship between levels of 25-hydroxyvitamin D3 and complement C3 (Rho = 0.09; p = 0.12) or C4 (Rho = 0.09; p = 0.13). Both 25-hydroxyvitamin D3 deficiency and anti-C1q were more specific but less sensitive than anti-dsDNA for concurrent clinical renal and non-renal SLE activity. Levels of 25-hydroxyvitamin D3, anti-dsDNA or anti-C1q did not correlate significantly with the SLE damage scores. Conclusions: 25-hydroxyvitamin D3 correlated inversely and significantly with clinical SLE activity, anti-C1q and anti-dsDNA titers, but not with complement levels or damage scores. Deficiency of 25-hydroxyvitamin D3 was as specific as anti-C1q, but less sensitive than anti-dsDNA, for detecting concurrent renal and non-renal clinical activity of SLE.

Migration of silver from nanosilver-polyethylene composite packaging into food simulants

An analytical method for the determination of silver in food simulants (3% (w/v) aqueous acetic acid or 95% (v/v) aqueous ethanol) was developed based on inductively coupled plasma mass spectrometry (ICP-MS). Recoveries ranged from 87% to 109% and RSDs ranged from 0.7% to 7.8%. The procedure was applied to determine the migration of silver from nanosilver-polyethylene food packaging film into food simulants at different temperatures and migration times. Results indicated that the maximum migration ratios were 1.70%, 3.00% and 5.60% for 3% (w/v) aqueous acetic acid at 20, 40 and 70 °C, respectively, while for 95% (v/v) aqueous ethanol the maximum migration ratios were 0.24%, 0.23% and 0.22% at 20, 40 and 70 °C.

Molecular level dynamics of genetic oscillator--the effect of protein-protein interaction

Uncovering how interactions of a set of molecular components influence the system's dynamic behavior is important for understanding intracellular processes and elucidating design principles, but unfortunately, there are limited efforts for studying this issue. Here, we study the effect of distinct post-translational dynamics controlled by protein dimerization on oscillations in the repressilator. For this, we propose three biologically motivated model scenarios of the repressilator with monomer or dimer being the active form of repressor, and with protein-protein interactions. It is found that the dimer dissociation constant can tune oscillatory regions, frequency and amplitude. Introducing a modified linear noise approximation to evaluate fluctuations of amplitude and period in the oscillatory systems, we show that different dimerization leads to a different effect on period and amplitude in reducing noise. The manipulation of the circuit's biochemical properties provides a practical strategy for designing a robust and tunable oscillator.

Implanted bone marrow-derived mesenchymal stem cells fail to metabolically stabilize or recover electromechanical function in infarcted hearts

Mesenchymal stem cells (MSCs) have been used with success in several clinical applications for clinical treatment of ischemic hearts. However, the reported effects of MSC-based therapy on myocardial infarction (MI) are inconsistent. In particular, the preventive effects of MSC-based therapy on arrhythmic sudden death and metabolic disorders after infarction remain controversial. Here, we investigated the effects of MSCs on reverse remodeling in an infarcted myocardium, and found that MSC-therapy failed to achieve the complete regeneration of infarcted myocardium. Histological analyses showed that although infarct size and interstitial fibrosis induced by MI recovered significantly after MSC treatment, these improvements were marginal, indicating that a significant amount of damaged tissue was still present. Furthermore, transplanted MSCs had slight anti-apoptotic and anti-inflammatory effects in MSC-implanted regions and no significant improvements in cardiac function were observed, suggesting that naïve MSCs might not be the right cell type to treat myocardial infarction. Furthermore, small ion profiling using ToF-SIMS revealed that the metabolic stabilization provided by the MSCs implantation was not significant compared to the sham group. Together, these results indicate that pretreatment of MSCs is needed to enhance the benefits of MSCs, particularly when MSCs are used to treat arrhythmogenicity and metabolically stabilize infarcted myocardium.

Assessment of New Relation for the Elastic Compliance of a Film-Substrate System

A new closed-form relation for the elastic compliance of a film-substrate system indented by a flat cylindrical punch is presented. The relation is an extension of the work of Gao at al. [1] modified to increase the applicable range of modulus mismatch between the film and substrate. The accuracy of the relation is assessed by comparison to finite element simulations, other approximate numerical solutions, and nanoindentation experiments performed on a fluorinated silicate glass (FSG) film on a silicon substrate. The benefits and limitations of the relation are discussed.

Effect of exercise training intensity on murine T-regulatory cells and vaccination response

To understand the underlying mechanism(s) for the effect of exercise at different intensities on T cell and DNA vaccination responses, we treated mice in a training protocol with regular moderate-intensity exercise (MIE) or prolonged, exhaustive high-intensity exercise (HIE). After 6 weeks of training, splenocytes were isolated to evaluate cytokine expression and T-regulatory (Treg) cell proportion by RT-PCR and FACS, respectively. Another set of mice that completed the same training protocol were used to determine DNA vaccination responses. These mice were immunized three times with HBV DNA vaccine at 2-week intervals and euthanized on day 14 after the last immunization. Serum and splenocytes were isolated to determine humoral and cell-mediated immunity (CMI). Results showed that HIE increased anti-inflammatory cytokine expression and CD4(+) CD25(+) Treg cell proportion. Further, HIE decreased IFN-γ expression, T-lymphocyte proliferation, and antigen-specic cytotoxic response in HBV DNA vaccine-immunized mice. MIE did not change anti-inflammatory cytokine expression or CD4(+) CD25(+) Treg cell proportion but increased pro-inflammatory cytokine expression and augmented antigen-specific CMI. Thus, MIE lower the risk of cancer and infectious illness through enhancing the pro-inflammatory responses. By contrast, HIE might increase the risk of common infections, such as upper respiratory tract infection, due to an up-regulation of CD4(+) CD25(+) Treg cells and anti-inflammatory responses.

Phase II study of fixed-dose-rate infusion of gemcitabine and UFT combination chemotherapy in patients with advanced bile duct cancer: Daegu Gyeoungbuk Oncology Group

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Background: This phase II study evaluated efficacy of fixed dose rate (FDR) infusion of gemcitabine (10mg/m2/min) and UFT combination in chemo-naïve patients with advanced bile duct cancer.

Methods: This was an open-label, single-arm, multicenter, phase II study with a Simon two-stage minimax design. Patients received the FDR gemcitabine 1,000mg/m2 for 3 consecutive weeks and UFT 400 mg/m2 on days 1-21. The cycle was repeated every 28 days. The primary end point was Response Evaluation Criteria in Solid Tumors (RECIST) -defined objective response rate. Secondary end points included clinical benefit response (CBR), safety, progression-free survival (PFS), and overall survival (OS). Clinical characteristics including four single nucleotide polymorphisms in DNA repair genes (RecQ1, RAD54L, XRCC1, ATM) were evaluated whether these influence the overall survival.

Results: Between December 2006 and February 2008, fifty-one patients were enrolled, with a median age of 58 years. The majority of patients (76%) had intra-hepatic disease. Fourteen patients (27%) had a RECIST investigator-assessed, partial response (PR); disease control rate (PR + stable disease) was 55%. CBR was 14% among 37 evaluable patients. Hematologic toxicity was main grade 3 or 4 treatment-related adverse events. Median PFS was 4.0 months (95% CI, 2.9 to 5.1 months). Median OS was 7.0 months (95% CI, 3.5 to 10.5 months). Intrahepatic disease, poor performance, and, XRCC1 R194W C/C type were predictive markers of poor overall survival.

Conclusions: FDR gemcitabine and UFT demonstrated apparent activity in patients with advanced bile duct cancer. However, this activity did not translate to prolong survival. The location of disease, performance status, and, polymorphic variants of DNA repair genes may affect clinical outcome of patients with advanced bile duct cancer.

No significant financial relationships to disclose.