A schematic reconstruction of fossil <i>Ephedra carnosa</i> female cone and its seed.

<p>A. The triovulate cone of <i>E. carnosa</i>, bearing three spreading, fleshy bracts (b) and three female reproductive units (fru). B. The seed, showing the outer envelope (oe), inner integument (i) and a micropylar tube (mt).</p

Fossil locality showing Beipiao (red dot) of Liaoning Province, Northeast China after [<b>40</b>].

<p>Fossil locality showing Beipiao (red dot) of Liaoning Province, Northeast China after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053652#pone.0053652-Sun2" target="_blank">[<b>40</b>]</a>.</p

Visualizing and Quantifying Protein PolySUMOylation at the Single-Molecule Level

Protein polySUMOylation, the attachment of small ubiquitin-like modifier (SUMO) chains to the target protein, is associated with a variety of physiological processes. However, the analysis of protein polySUMOylation is often complicated by the heterogeneity of SUMO–target conjugates. Here, we develop a new strategy to visualize and quantify polySUMOylation at the single-molecule level by integrating the tetracysteine (TC) tag labeling technology and total internal reflection fluorescence (TIRF)-based single-molecule imaging. As a proof-of-concept, we employ the human SUMO-2 as the model. The addition of TC tag to SUMO-2 can specifically translate the SUMO-mediated modification into visible fluorescence signal without disturbing the function of SUMO-2. The SUMO monomers display homogeneous fluorescence spots at the single-molecule level, whereas the mixed SUMO chains exhibit nonuniform fluorescence spots with a wide range of intensities. Analysis of the number and the brightness of fluorescence spots enable quantitative measurement of the polySUMOylation degree inside the cells under different physiological conditions. Due to the frequent occurrence of posttranslational modification by polymeric chains in cells, this single-molecule strategy has the potential to be broadly applied for studying protein posttranslational modification in normal cellular physiology and disease etiology

Representative female cones of three sections in <i>Ephedra</i>.

<p>A. A membranous female cone of <i>E. californica</i> Watson in Sect. <i>Alatae</i> Stapf. B. A coriaceous female cone of <i>E. strobilacea</i> Bunge in Sect. <i>Asarca</i> Stapf. C. A fleshy female cone of <i>E. intermedia</i> Schrenk et Mey. in Sect. <i>Ephedra</i>.</p

Distribution of extant <i>Ephedra</i> (green regions) after [<b>5</b>] (red dot showing the present fossil locality).

<p>Distribution of extant <i>Ephedra</i> (green regions) after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053652#pone.0053652-Caveney1" target="_blank">[<b>5</b>]</a> (red dot showing the present fossil locality).</p

Fossil <i>Ephedra carnosa</i> Yang et Wang.

<p>A–B. A fleshy female cone and an associated axis. Holotype: PE 20120319A, B (part and counterpart). C–D. Enlargment of the female cone, showing morphology of three seeds. E. Close-up of the middle seed, showing a thin outer envelope and a straight micropylar tube. PE 20120319A. F–G. Close-up of the fleshy bract, bearing two veins sub-parallel in the middle-upper part and divergent toward the basal part. H. Another fleshy female cone. Paratype: PE 2012071006. I. Close-up of three seeds in Fig. H.</p

Key to extant and fossil species in <i>Ephedra</i> and other ephedroids.

<p>Key to extant and fossil species in <i>Ephedra</i> and other ephedroids.</p

Spatiotemporal Characterization of Ambient PM_2.5 Concentrations in Shandong Province (China)

China experiences severe particulate matter (PM) pollution problems closely linked to its rapid economic growth. Advancing the understanding and characterization of spatiotemporal air pollution distribution is an area where improved quantitative methods are of great benefit to risk assessment and environmental policy. This work uses the Bayesian maximum entropy (BME) method to assess the space–time variability of PM_2.5 concentrations and predict their distribution in the Shandong province, China. Daily PM_2.5 concentrations obtained at air quality monitoring sites during 2014 were used. On the basis of the space–time PM_2.5 distributions generated by BME, we performed three kinds of querying analysis to reveal the main distribution features. The results showed that the entire region of interest is seriously polluted (BME maps identified heavy pollution clusters during 2014). Quantitative characterization of pollution severity included both pollution level and duration. The number of days during which regional PM_2.5 exceeded 75, 115, 150, and 250 μg m^–3 varied: 43–253, 13–128, 4–66, and 0–15 days, respectively. The PM_2.5 pattern exhibited an increasing trend from east to west, with the western part of Shandong being a heavily polluted area (PM_2.5 exceeded 150 μg m^–3 during long time periods). Pollution was much more serious during winter than during other seasons. Site indicators of PM_2.5 pollution intensity and space–time variation were used to assess regional uncertainties and risks with their interpretation depending on the pollutant threshold. The observed PM_2.5 concentrations exceeding a specified threshold increased almost linearly with increasing threshold value, whereas the relative probability of excess pollution decreased sharply with increasing threshold

Ultrasensitive Detection of Transcription Factors Using Transcription-Mediated Isothermally Exponential Amplification-Induced Chemiluminescence

Transcription factors (TFs) are important cellular components that modulate gene expression, and the malregulation of transcription will lead to a variety of diseases such as cancer and developmental syndromes. However, the conventional methods for transcription factor assay are generally cumbersome and costly with low sensitivity. Here, we develop a label-free strategy for ultrasensitive detection of transcription factors using a cascade signal amplification of RNA transcription, dual isothermally exponential amplification reaction (EXPAR), and G-quadruplex DNAzyme-driven chemiluminescence. Briefly, the specific binding of TF with the detecting probe prevents the cleavage of the detecting probe by exonuclease and subsequently facilitates the conversion of TF signal to abundant RNA triggers in the presence of T7 RNA polymerase. The obtained RNA triggers can initiate the strand displacement amplification to yield abundant DNAzymes and DNA triggers, and the released DNA triggers can further initiate the next rounds of EXPAR reaction. The synergistic operation of dual EXPAR reaction can produce large amounts of DNAzymes, which subsequently catalyze the oxidation of luminol by H₂O₂ to yield an enhanced chemiluminescence signal with the assistance of cofactor hemin. Conversely, in the absence of target TF, the naked detecting probes will be completely digested by exonucleases, leading to neither the transcription-mediated EXPAR nor the DNAzyme-driven chemiluminescence signal. This method has a low detection limit of as low as 6.03 × 10^–15 M and a broad dynamic range from 10 fM to 1 nM and can even measure the NF-κB p50 of crude cell nuclear extracts. Moreover, this method can be used to measure a variety of DNA-binding proteins by simply substituting the target-specific binding sequence in the detecting probes

Toward Biocompatible Semiconductor Quantum Dots: From Biosynthesis and Bioconjugation to Biomedical Application

Toward Biocompatible Semiconductor Quantum Dots: From Biosynthesis and Bioconjugation to Biomedical Applicatio