Applying ant colony algorithm to identify ecological security patterns in megacities

Ecological security patterns composed of ecological sources and corridors provide an effective approach to conserving natural ecosystems. Although the direction of ecological corridors has been identified in previous studies, the precise range remains unknown. To address this crucial gap, ant colony algorithm and kernel density estimation were applied to identify the range and restoration points of ecological corridors, which is important for natural conservation and ecological restoration. In this case study of Beijing City, ecological sources were identified based on habitat importance and landscape connectivity. The results showed that, in total 3119.65 km2 of ecological land had been extracted as ecological sources, which were mainly located in the northern, northwestern and northeastern mountainous areas. The identified key ecological corridor covered an area of 198.86 km2, with 567.30 km2 for potential ecological corridors, both connecting the ecological sources. 34 key points were also identified with priority in restoring ecological corridors

Association between surgical extent and recurrence in unilateral intermediate- to high-risk papillary thyroid cancer

Abstract Background Guidelines recommend total thyroidectomy (TT) to facilitate radioactive ablation and serological follow-up for intermediate- to high-risk papillary thyroid carcinoma (PTC). However, the association between surgical extent and tumor recurrence in these patients has not been well validated. We aimed to examine the association between the extent of surgery and recurrence in patients with completely resected unilateral intermediate- to high-risk PTC. Methods Patients with completely resected unilateral PTC from 2000 to 2017 in a single institute were reviewed. Those who had extrathyroidal extension (ETE) or lymph node metastasis (LNM, cN1 or pN1 > 5 lymph nodes involved) were included for analysis. Cox proportional hazards models were applied to measure the association between surgical extent and recurrence-free survival (RFS) while adjusting for patient demographic, clinicopathological and treatment variables. Results A total of 4550 patients (mean[SD] age, 43.0[11.7] years; 3379 women[74.3%]) were included. Of these patients, 2262(49.7%), 656(14.4%), 1032(22.7%), and 600 (13.2%) underwent lobectomy, TT, lobectomy + neck dissection (ND) and TT + ND, respectively. With a median follow-up period of 68 months, after multivariate adjustment, lobectomy was associated with a compromised RFS compared with other surgical extents (HR[95%CI], TT 0.537[0.333–0.866], P = 0.011, lobectomy + ND 0.531[0.392–0.720] P < 0.0001, TT + ND 0.446[0.286–0.697] P < 0.0001). RFS was similar between the two extents with ND (lobectomy + ND, HR [95%CI], 1.196 [0.759–1.885], P = 0.440). Conclusion Lobectomy alone is associated with an elevated recurrence risk in patients with unilateral intermediate- to high-risk PTC compared with larger surgical extents. However, lobectomy and ND may provide similar tumor control compared with the conventional approach of TT and ND

Exfoliated Molybdenum Disulfide Encapsulated in a Metal Organic Framework for Enhanced Photocatalytic Hydrogen Evolution

An exfoliated MoS2 encapsulated into metal-organic frameworks (MOFs) was fabricated as a promising noble-metal-free photocatalyst for hydrogen production under visible light irradiation. The as-synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer&ndash;Emmett&ndash;Teller (BET) surface analysis. It is well known that bulk MoS2 is unsuitable for photocatalysis due to its inadequate reduction and oxidation capabilities. However, exfoliated MoS2 exhibits a direct band gap of 2.8 eV due to quantum confinement, which enables it to possess suitable band positions and retain a good visible-light absorption ability. As a result, it is considered to be an encouraging candidate for photocatalytic applications. Encapsulating exfoliated MoS2 into MOF demonstrates an improved visible light absorption ability compared to pure MOF, and the highest hydrogen production rate that the encapsulated exfoliated MoS2 could reach was 68.4 &mu;mol h-1g-1, which was much higher than that of pure MOF. With a suitable band structure and improved light-harvesting ability, exfoliated MoS2@MOF could be a potential photocatalyst for hydrogen production

Microbial diversity in two cold springs on the Qinghai-Tibetan Plateau

The microbial diversity in Wuli Area, Qinghai-Tibetan Plateau was investigated using 16S rRNA gene phylogenetic analyses. A total of 117 bacterial and 66 archaeal 16S rRNA gene clones were obtained from the Wuli cold springs. The bacterial clones could be classified into Proteobacteria, Acidobacteria, Deinococci, Sphingobacteria, Flavobacteria, Nitrospirae, Actinobacteria, Gemmatimonadetes, and unclassified-bacteria; and the archaeal clones could be classified into Crenarchaeota and Thaumarchaeota. Among the major groups, Proteobacteria and Crenarchaeota were dominant in the bacterial and archaeal 16S rRNA gene clone libraries, respectively. The clone sequences obtained in Wuli cold springs were closely related to those from cold habitats, such as snow/ice/soils on high mountains or at high latitude. Especially, the microbial community composition of Wuli Area was more similar to that in Tibetan glaciers than cold environments of other locations. The data presented in this study have implications for a better understanding of microbial diversity in cold springs on the Qinghai-Tibetan Plateau

Sensitive Electrochemical Detection of Human Methyltransferase Based on a Dual Signal Amplification Strategy Coupling Gold Nanoparticle–DNA Complexes with Ru(III) Redox Recycling

Effective detection of DNA methyltransferase (DNMT) activity is significant for cancer research. Herein, we developed a sensitive electroanalytical method to detect human DNA (cytosine-5)–methyltransferase 1 (DNMT1) from crude lysates of cancer cells. In this assay, capture DNA having a preferred DNMT1 methylation site was immobilized on a gold electrode and then hybridized with gold nanoparticle (Au NP)–DNA complexes. The modified electrodes were equilibrated with the lysate and then incubated with methylation-sensitive restriction enzyme. If the lysate was negative for DNMT1 activity, the Au NP–DNA complexes would be cut by the restriction enzyme and released from the electrode. Conversely, restriction enzyme cleavage would be blocked by the fully methylated duplexes, and the Au NP–DNA complexes would remain on the electrode. Electroactive Ru­(NH₃)₆³⁺ was used as the signal reporter, because of its electrostatic attraction to DNA, resulting in an electrochemical signal. Since the electrochemical signal reflects the amount of Ru­(III) redox and the amount of Ru­(III) redox is correlated with the activity of DNMT1, the activity of DNMT1 is proportional to the electrochemical signal. The signal could be amplified by the numerous DNAs on the Au NPs and further amplified by Ru­(III) redox recycling. With this method, a detection limit down to 0.3 U/mL for pure DNMT1 and 8 MCF-7 cells was achieved. DNMT1 activities of different cell lines were also successfully evaluated

Highly Sensitive Electrochemical Detection of Tumor Exosomes Based on Aptamer Recognition-Induced Multi-DNA Release and Cyclic Enzymatic Amplification

Sensitive and specific detection of tumor exosomes is of great significance for early cancer diagnosis. In this paper, we report an aptamer strategy for exosome detection based on aptamer recognition-induced multi-DNA release and cyclic enzymatic amplification. First, we use aptamer–magnetic bead bioconjugates to capture tumor exosomes derived from LNCaP cells, leading to the release of three kinds of messenger DNAs (mDNAs). After magnetic separation, the released mDNAs hybridized with the probe DNAs immobilized on a gold electrode. Electroactive Ru­(NH₃)₆³⁺ was used as the signal reporter because of its electrostatic attraction to DNA. Subsequent Exo III cyclic digestion caused the electrochemical signal to “turn off”. Because the electrochemical signal reflects the concentration of Ru­(NH₃)₆³⁺ and the concentration of Ru­(NH₃)₆³⁺ is correlated with the mDNA concentration, which is correlated with the exosome concentration, the tumor exosomes can be detected by examining the decrease in the peak current of Ru­(NH₃)₆³⁺. In this paper, the signal was amplified by the numerous mDNAs released from the magnetic bead and the Exo III-assisted mDNA recycling. Under the optimal conditions, a detection limit down to 70 particles/μL was achieved, which is lower than the LODs of most currently available methods. Furthermore, this assay can be used to detect tumor exosomes in complex biological samples, demonstrating potential application in real sample diagnosis

Control of Temperature on Microbial Community Structure in Hot Springs of the Tibetan Plateau

<div><p>The Tibetan Plateau in Northwest China hosts a number of hot springs that represent a biodiversity hotspot for thermophiles, yet their diversity and relationship to environmental conditions are poorly explored in these habitats. In this study we investigated microbial diversity and community composition in 13 Tibetan hot springs with a wide range of temperatures (22.1–75°C) and other geochemical conditions by using the 16S rRNA gene pyrosequencing approach. <i>Bacteria</i> (10⁸–10¹¹ copy/g; 42 bacterial phyla) in Tibetan hot springs were more abundant and far more diverse than <i>Archaea</i> (10⁷–10¹⁰ copy/g; 5 archaeal phyla). The dominant bacterial phyla systematically varied with temperature. Moderate temperatures (75–66°C) favored Aquificae, GAL35, and novel <i>Bacteria</i>, whereas low temperatures (60–22.1°C) selected for Deinococcus-Thermus, Cyanobacteria, and Chloroflexi. The relative abundance of Aquificae was correlated positively with temperature, but the abundances of Deinococcus-Thermus, Cyanobacteria, and Chloroflexi were negatively correlated with temperature. Cyanobacteria and Chloroflexi were abundant in Tibetan hot springs and their abundances were positively correlated at low temperatures (55–43°C) but negatively correlated at moderate temperatures (75–55°C). These correlation patterns suggest a complex physiological relationship between these two phyla. Most archaeal sequences were related to Crenarchaeota with only a few related to Euryarchaeota and Thaumarchaeota. Despite the fact that microbial composition in Tibetan hot springs was strongly shaped by temperature, microbial diversity (richness, evenness and Shannon diversity) was not significantly correlated with temperature change. The results of this study expand our current understanding of microbial ecology in Tibetan hot springs and provide a basis for a global comparison.</p></div

Primer sets used for qPCR.

<p>Primer sets used for qPCR.</p

Correlations between the relative abundances of dominant microbial groups and temperature.

<p>The relative abundance of Aquificae (<b>A</b>) shows a positive correlation with temperature, whereas the relative abundances of the phyla Deinococcus-Thermus (<b>B</b>), Cyanobacteria (<b>C</b>) and Chloroflexi (<b>D</b>) as well as the class <i>Chloroflexi</i> (E) show negative correlations with temperature. The relative abundance of Cyanobacteria and temperature was not significantly correlated (R² = 0.23; p<0.5) (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062901#pone-0062901-g005" target="_blank">Figure 5C</a>); when the two outliers (springs NM6 and NM7, where Cyanobacteria were minor) were omitted, the linear correlation was dramatically improved (R² = 0.90; p<0.005) (figure not shown). When qPCR data were used for Cyanobacteria (<b>C</b>) and class-level <i>Chloroflexi</i> (E), similar correlations resulted (data not shown for clarity).</p

Comparison of alpha diversity.

<p>Calculation of microbial Richness, Equitability, and Shannon diversity among the pooled samples for the low temperature cluster (60–22.1°C), the moderate temperature cluster (75–66°C), and the soil cluster at four OTU levels: 97%, 95%, 90%, and 80%. Error bars indicate standard error of the mean. Pairwise t tests were performed for each pair of comparisons, moderate vs. low temperature, moderate temperature vs. soil, and low temperature vs. soil at each OTU level. Symbols ***indicates p<0.001; **p<0.01; *p<0.05;. p<0.1; ∼ non-significant. A Bonferrroni correction was made for the number of comparisons.</p