Coral-associated bacteria, quorum sensing disrupters, and the regulation of biofouling

<div><p>Marine biofouling, the settlement of microorganisms and macroorganisms on structures submerged in seawater, although economically detrimental, is a successful strategy for survival in hostile environments, where coordinated bacterial communities establish biofilms <i>via</i> the regulation of quorum sensing (QS) communication systems. The inhibition of QS activity among bacteria isolated from different coral species was investigated to gain further insight into its potency in the attenuation, or even the prevention, of undesirable biofouling on marine organisms. It is hypothesized that coral mucus/microorganism interactions are competitive, suggesting that the dominant communities secrete QS disruptive compounds. One hundred and twenty bacterial isolates were collected from healthy coral species and screened for their ability to inhibit QS using three bioreporter strains. Approximately 12, 11, and 24% of the isolates exhibited anti-QS activity against <i>Escherichia coli</i> pSB1075, <i>Chromobacterium violaceum</i> CV026, and <i>Agrobacterium tumefaciens</i> KYC55 indicator strains, respectively. Isolates with positive activity against the bioluminescent monitor strains were scanned <i>via</i> a cytotoxic/genotoxic, <i>E. coli</i> TV1061 and DPD2794 antimicrobial panel. Isolates detected by <i>C. violaceum</i> CV026 and <i>A. tumefaciens</i> KYC55 reporter strains were tested for their ability to inhibit the growth of these reporter strains, which were found to be unaffected. Tests of the <i>Favia</i> sp. coral isolate Fav 2-50-7 (>98% similarity to <i>Vibrio harveyi</i>) for its ability to attenuate the formation of biofilm showed extensive inhibitory activity against biofilms of <i>Pseudomonas aeruginosa</i> and <i>Acinetobacter baumannii</i>. To ascertain the stability and general structure of the active compound, cell-free culture supernatants exposed to an increasing temperature gradient or to digestion by proteinase K, were shown to maintain potent QS attenuation and the ability to inhibit the growth of biofilms. Mass spectrometry confirmed the presence of a low molecular mass compound. The anti-QS strategy exemplified in the coral mucus is a model with potentially wide applications, including countering the ecological threat posed by biofilms. Manipulating synchronized bacterial behavior by detecting new QS inhibitors will facilitate the discovery of new antifouling compounds.</p> </div

Micelle-Assisted Confined Coordination Spaces for Benzimidazole: Enhanced Electrochemiluminescence for Nitrite Determination

Selective and sensitive detection of nitrite has important medical and biological implications. In the present work, to obtain an enhanced electrochemiluminescence (ECL) determination of nitrite, a novel nano-ECL emitter CoBIM/cetyltrimethylammonium bromide (CTAB) was prepared via a micelle–assisted, energy-saving, and ecofriendly method based on benzimidazole (BIM) and CTAB. Unlike conventional micelle assistance, the deprotonated BIM (BIM–) preferential placement was in the palisade layer of cationic CTAB-based micelles. Enriching the original CTAB micelle with BIM– disrupted its stability and resulted in the formation of considerably smaller BIM/CTAB-based micelles, providing a confined coordination environment for BIM– and Co2+. As a result, the growth of CoBIM/CTAB was also limited. Owing to the unusual nitration reaction between BIM and nitrite, the prepared CoBIM/CTAB was successfully applied as a novel ECL probe for the detection of nitrite with a wide linear range of 1–1500 μM and a low detection limit of 0.67 μM. This work also provides a promising ECL platform for ultrasensitive monitoring of nitrite and it was applied with sausages and pickled vegetables

CCR5-peptidoliposomes enhance the ability of soluble CD4 mimetic to inhibit infection of R5-tropic HIV-1.

<p>CCR5-peptidoliposomes were co-incubated for 2 h with R5-tropic JRFL-pseudotyped HIV-1 (A); R5-tropic ADA-pseudotyped HIV-1 (B); or X4-tropic HXB2-pseudotyped HIV-1 (C), in the presence or absence of different concentrations of sCD4M48. Peptide-free magnetic liposomes (in the absence of sCD4M48) were used as control (set to 100% infectivity). The virus was separated from the beads by a magnetic field and TZM-HeLa-β-gal target cells were infected for 4 h. β-gal expression was carried out 48 h post infection. An unpaired <i>t</i>-test (two-tailed) was used to assess the significance of the difference in the means observed between the two groups indicated, <i>p</i> < 0.05. The data are mean ± S.E.M. calculated from three independent experiments each performed in duplicate.</p

Magnetic liposome population is homogeneous.

<p>The magnetic liposomes were prepared using a lipid mixture POPC:POPE:DMPA (molar ratio 6:3:1) containing 1% Biotinyl-DOPE in the presence (black peak) or absence (white peak) of 1% Rhodamine–DOPE, and analyzed by FACS as described in the Materials and Methods. FL1-H designates the height of the photon peak obtained by using a 525/50 band pass filter (FL1). The figure shows the data for an experiment representative of two similar experiments.</p

Effect of co-display of CD4- and CCR5-peptidomimetics on the ability of CCR5-peptidoliposomes to inhibit HIV-1.

<p>R5-tropic JRFL-pseudotyped HIV-1 was co-incubated for 2 h with: CCR5-Beads–peptidoliposomes containing 5% each of NT-3FSN-CCR5-PAL and ECL2-CCR5-2PAL, or (CD4+CCR5)-Beads–peptidoliposomes containing 5% each of CD4M48-PAL, ECL2-CCR5-2PAL and NT-3FSN-CCR5-PAL. Peptide-free magnetic liposomes were used as control (set to 100% infectivity). The virus was separated from the beads by a magnetic field and TZM-HeLa-β-gal target cells were infected for 4 h. β-gal expression was carried out 48 h post infection. The data are mean ± S.E.M. calculated from three independent experiments each performed in duplicate.</p

CCR5-peptidoliposomes bind soluble recombinant gp120.

<p>Peptidoliposomes were incubated with 4 μM soluble recombinant His-tagged gp120 for 1 h at 37°C and the binding was assessed as described in the Materials and Methods. Mimetics used: mCD4 –CD4M48-PAL (1%); mCCR5-Nt – NT-2Y-CCR5-PAL (1%); mCCR5-ECL2 –ECL2-CCR5-2PAL (1%); mCCR5-Nt-3FSN–NT-3FSN-CCR5-PAL (1%); sCD4M48 –soluble M48 peptide (10 μM) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144043#pone.0144043.ref015" target="_blank">15</a>]. Control – peptide-free magnetic liposomes. <i>p</i> < 0.05. The data are mean ± S.E.M. calculated from three independent experiments each performed in triplicate.</p

Palmitoylated CCR5-peptidomimetics can be displayed on liposome surface.

<p>Peptidoliposomes were generated in the presence of increasing concentrations (molar %) of NT-2Y-CCR5-PAL (A) or ECL2-CCR5-2PAL (B) in the lipid mixture. (C) Peptidoliposomes were formed in the presence of 1% ECL2-CCR5-2PAL and the indicated concentrations of NT-2Y-CCR5-PAL in the lipid mixture. Peptidoliposomes were reacted with anti-CCR5 N-terminus polyclonal antibody (ab 7346, Abcam) (A) or with anti-CCR5 ECL2 (raised against a synthetic peptide 2D7-2SK [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144043#pone.0144043.ref044" target="_blank">44</a>]) polyclonal antibody (ab 36818, Abcam) (B and C), followed by a secondary HRP-conjugated antibody (ab 7090, Abcam) and analyzed as described in the Materials and Methods. Control – peptide-free magnetic liposomes. The data are mean ± S.E.M. calculated from three independent experiments each performed in triplicate.</p

HIV-1 incubation with CCR5-peptidoliposomes does not deplete viral loads.

<p>JRFL-pseudotyped HIV-1 was incubated for 2 h with peptidoliposomes in the presence or absence of M48 peptide–sCD4M48 (10 μM). CCR5-Beads - peptidoliposomes containing 5% each of NT-3FSN-CCR5-PAL and ECL2-CCR5-2PAL; (CD4+CCR5)-Beads - peptidoliposomes containing 5% each of CD4M48-PAL, ECL2-CCR5-2PAL and NT-3FSN-CCR5-PAL. At the end of the incubation, the supernatant and liposome fractions were analyzed by ELISA for the presence of HIV-p24 antigen as described in the Materials and Methods. Peptide-free magnetic liposomes were used as the control (p24 count in the supernatant set to 100%). The data are mean ± S.E.M. calculated from three independent experiments each performed in duplicate.</p

Tunable Chemical Release from Polyester Thin Film by Photocatalytic Zinc Oxide and Doped LiYF₄ Upconverting Nanoparticles

Once manufactured or implanted, polyester release kinetics tend to be fixed with little modulation possible for optimal local chemical concentrations. Here, a typical implantable polyester was fabricated into thin films (∼50 μm thick) with additives of photocatalytic ZnO nanoparticles, lanthanide-doped LiYF₄ nanoparticle upconverting nanoparticles, or a combination thereof and irradiated with either 6 mW ultraviolet (365 nm) light emitting diodes or 50 mW near-infrared (980 nm) laser diodes to induce polymer photooxidation. Irradiated polyester films with the aforementioned photoadditives had enhanced release kinetics up to 30 times more than nonirradiated, neat films with extended release times of 28 days. Near-infrared, ZnO-mediated photocatalysis had the highest light on/light off ratio release kinetics of 15.4, while doped LiYF₄ upconversion nanoparticles paired with ZnO nanoparticles had the highest linear <i>R</i>² correlation of 0.98 with respect to duty cycle and release kinetics. Future applications of the technology will aim toward modulation of previously developed polymeric reagents/drugs for real-time, feedback-optimized release

Editorial Special Issue Introduction Algorithmic Game Theory

n We briefly survey the rise of game theory as a topic of study in artificial intelligence an