The proteomic response of the reef coral <i>Pocillopora acuta</i> to experimentally elevated temperatures

<div><p>Although most reef-building corals live near the upper threshold of their thermotolerance, some scleractinians are resilient to temperature increases. For instance, <i>Pocillopora acuta</i> specimens from an upwelling habitat in Southern Taiwan survived a nine-month experimental exposure to 30°C, a temperature hypothesized to induce stress. To gain a greater understanding of the molecular pathways underlying such high-temperature acclimation, the protein profiles of experimental controls incubated at 27°C were compared to those of conspecific <i>P</i>. <i>acuta</i> specimens exposed to 30°C for two, four, or eight weeks, and differentially concentrated proteins (DCPs) were removed from the gels and sequenced with mass spectrometry. Sixty unique DCPs were uncovered across both eukaryotic compartments of the <i>P</i>. <i>acuta-</i>dinoflagellate (genus <i>Symbiodinium</i>) mutualism, and <i>Symbiodinium</i> were more responsive to high temperature at the protein-level than the coral hosts in which they resided at the two-week sampling time. Furthermore, proteins involved in the stress response were more likely to be documented at different cellular concentrations across temperature treatments in <i>Symbiodinium</i>, whereas the temperature-sensitive host coral proteome featured numerous proteins involved in cytoskeletal structure, immunity, and metabolism. These proteome-scale data suggest that the coral host and its intracellular dinoflagellates have differing strategies for acclimating to elevated temperatures.</p></div

Pie graphs showing breakdown of differentially concentrated proteins (DCPs) between control (C4) and high (H4) temperature samples of the four-week sampling time.

<p>Four and four protein spots were found to be more highly concentrated in the C4 (i.e., C>H) and H4 (H>C) proteomes, respectively, and 8 C>H and 4 H>C DCPs were identified from these eight spots. When the host:<i>Symbiodinium</i> (Sym) ratio was significantly higher (<i>z</i>-test, <i>p</i><0.05) than the <i>P</i>. <i>acuta</i>:Sym mRNA ratio of 1.9±0.4 (std. dev.), a bar has been inserted over the word “host” in (a-c). Likewise, when a cellular process was over-represented in the proteomes of the host (g-i) and Sym (j-l) relative to the host coral and Sym transcriptomes [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192001#pone.0192001.ref029" target="_blank">29</a>], respectively (2-sample proportion test, <i>p</i><0.05), a bar has been placed over the category name.</p

Compartmental and functional breakdown of all differentially concentrated proteins (DCPs).

<p>Across the nine, eight, and eight differentially concentrated/uniquely synthesized protein spots removed from representative gels of the two-, four-, and eight-week sampling times, respectively, 75 DCPs were uncovered; upon counting five proteins sequenced at multiple time points only once, 37 and 23 of the 70 unique DCPs were found to be of host coral (<i>Pocillopora acuta</i>) and <i>Symbiodinium</i> (Sym) origin, respectively. When a cellular process was over-represented in the differentially concentrated proteomes of the host coral (g-i) and Sym (j-l) relative to the host coral and Sym transcriptomes [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192001#pone.0192001.ref029" target="_blank">29</a>], respectively (2-sample proportion test, <i>p</i><0.05), a bar has been inserted above the category name.</p

Pie graphs depicting breakdown of differentially concentrated proteins (DCPs) between control (C8) and high (H8) temperature samples of the eight-week sampling time.

<p>Two and six spots were more highly concentrated in the C8 (i.e., C>H) and H8 (H>C) proteomes, respectively, and 6 C>H and 19 H>C DCPs were identified from these eight spots. When the host:<i>Symbiodinium</i> (Sym) DCP ratio was significantly lower (<i>z</i>-test, <i>p</i><0.05) than the <i>P</i>. <i>acuta</i>: Sym mRNA ratio of 1.9±0.4 (std. dev.), a bar has been inserted under the word “host” in (a-c).</p

Summary of all unique host coral (<i>Pocillopora acuta</i>) and <i>Symbiodinium</i> differentially concentrated proteins (DCPs) uncovered across temperature treatments.

<p>Summary of all unique host coral (<i>Pocillopora acuta</i>) and <i>Symbiodinium</i> differentially concentrated proteins (DCPs) uncovered across temperature treatments.</p

Two-dimensional gel electrophoresis of proteins from representative control and high- temperature coral samples after two, four, and eight weeks of treatment exposure.

<p>Encircled and labeled protein spots were 1) determined to be differentially concentrated between temperature treatments within a sampling time with image analysis software, 2) removed from the gels, 3) purified, 4) digested with trypsin, and 5) submitted for sequencing by nano-liquid chromatography+mass spectrometry as described in the main text and the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192001#pone.0192001.s001" target="_blank">S1 File</a>. The isoelectric point (pI) and molecular weight (in kilodaltons [kDa]) were the 1^st and 2^nd dimensions, respectively. Only labeled spots were removed; in certain cases at the four- and eight-week sampling times, matched (i.e., same pI and molecular weight) spots have been encircled in gels of both treatments to emphasize their differential concentrations, yet they were not sequenced for reasons discussed in the main text. “C2” and "H2" = control and high-temperature samples at the two-week sampling time, respectively. “C4” and "H4" = control and high-temperature samples at the four-week sampling time, respectively. “C8” and "H8" = control and high-temperature samples at the eight-week sampling time, respectively.</p

Summary of the dataset.

<p>The number of differentially concentrated proteins (DCPs) was plotted over time for both the host coral (“H”) and <i>Symbiodinium</i> (“S;” Sym) for proteins documented at higher concentrations at high temperature (red icons) and those over-expressed at the control temperature (blue icons). The sizes of the icons are proportional to the host/Sym DCP ratio at each sampling time (listed at the top of the plot). The upper and lower hatched lines represent the total number of DCPs at each sampling time for the host coral and Sym, respectively. In (b) the sizes of the bubbles are proportional to the number of DCPs involved in each cellular process for both the host coral (b-1) and Sym (b-2). Purple bubbles represent those cellular processes for which one protein was over-expressed at high temperature, whereas another was documented at higher concentrations at the control temperature. This annotation is not used for the Sym “stress response” category at the two-week sampling time (b-2), in which 1 and 4 DCPs were more highly concentrated by the control and high-temperature samples, respectively. Underlined functional categories in b-2 reflect processes that were also temperature-sensitive in the host coral compartment (b-1).</p

Combined Tween 20-Stabilized Gold Nanoparticles and Reduced Graphite Oxide–Fe₃O₄ Nanoparticle Composites for Rapid and Efficient Removal of Mercury Species from a Complex Matrix

This study describes a simple method for removing mercuric ions (Hg²⁺) from a high-salt matrix based on the use of Tween-20-stabilized gold nanoparticles (Tween 20-Au NPs) as Hg²⁺ adsorbents and composites of reduced graphite oxide and Fe₃O₄ NPs as NP collectors. Citrate ions adsorbed on the surface of the Tween 20-Au NPs reduced Hg²⁺ to Hg⁰, resulting in the deposition of Hg⁰ on the surface of the NPs. To circumvent time-consuming centrifugation and transfer steps, the Hg⁰-containing gold NPs were collected using reduced graphite oxide–Fe₃O₄ NP composites. Compared with the reported NP-based methods for removing Hg²⁺, Tween 20-Au NPs offered the rapid (within 30 min), efficient (>99% elimination efficiency), durable (>10 cycles), and selective removal of Hg²⁺, CH₃Hg⁺, and C₂H₅Hg⁺ in a high-salt matrix without the interference of other metal ions. This was attributed to the fact that the dispersed Tween 20-Au NPs exhibited large surface-area-to-volume ratio to bind Hg²⁺ through Hg²⁺–Au⁺ metallophilic interactions in a high-salt matrix. The formation of graphite oxide sheets and reduced graphite oxide–Fe₃O₄ NP composites was demonstrated using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectrometry, and transmission electron microscopy. The mechanism of interaction between Tween 20-Au NPs and Hg²⁺ was studied using visible spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy

A hypothetical model for the alternative splicing of <i>GLA</i> (IVS4 + 919G>A).

<p>A hypothetical model for the alternative splicing of <i>GLA</i> (IVS4 + 919G>A).</p

Alterations in histone modification patterns after amiloride treatment.

<p>ChIP assays were performed with antibodies to the indicated histone modifications on the cryptic exon area in Int4 of <i>GLA</i> in normal cells or in FD cells treated with or without amiloride. Results were expressed as a fraction of histone H3 after normalization to input values and presented as a mean values ± standard deviation from three independent experiments. Asterisk represents significant difference (<i>p</i>-value < 0.05). FD cells, Fabry disease cells; Amil, amiloride.</p