Bacterial metabolites represent an invaluable source of bioactive molecules which can be used as such or serve as chemical frameworks for developing new antimicrobial compounds for various ...applications including crop protection against pathogens. Prodiginines are tripyrrolic, red-colored compounds produced by many bacterial species. Recently, due to the use of chemical-, bio-, or mutasynthesis, a novel group of prodiginines was generated. In our study, we perform different assays to evaluate the effects of prodigiosin and five derivatives on nematodes and plant pathogenic fungi as well as on plant development. Our results showed that prodigiosin and the derivatives were active against the bacterial feeding nematode
Caenorhabditis elegans
in a concentration- and derivative-dependent manner while a direct effect on infective juveniles of the plant parasitic nematode
Heterodera schachtii
was observed for prodigiosin only. All compounds were found to be active against the plant pathogenic fungi
Phoma lingam
and
Sclerotinia sclerotiorum.
Efficacy varied depending on compound concentration and chemical structure. We observed that prodigiosin (
1
), the 12 ring-
9
, and hexenol
10
derivatives are neutral or even positive for growth of
Arabidopsis thaliana
depending on the applied compound concentration, whereas other derivatives appear to be suppressive. Our infection assays revealed that the total number of developed
H. schachtii
individuals on
A. thaliana
was decreased to 50% in the presence of compounds
1
or
9
. Furthermore, female nematodes and their associated syncytia were smaller in size. Prodiginines seem to indirectly inhibit
H. schachtii
parasitism of the plant. Further research is needed to elucidate their mode of action. Our results indicate that prodiginines are promising metabolites that have the potential to be developed into novel antinematodal and antifungal agents.
Bacterial secondary metabolites exhibit diverse remarkable bioactivities and are thus the subject of study for different applications. Recently, the individual effectiveness of tripyrrolic ...prodiginines and rhamnolipids against the plant-parasitic nematode
, which causes tremendous losses in crop plants, was described. Notably, rhamnolipid production in engineered
strains has already reached industrial implementation. However, the non-natural hydroxyl-decorated prodiginines, which are of particular interest in this study due to a previously described particularly good plant compatibility and low toxicity, are not as readily accessible. In the present study, a new effective hybrid synthetic route was established. This included the engineering of a novel
strain to provide enhanced levels of a bipyrrole precursor and an optimization of mutasynthesis, i.e., the conversion of chemically synthesized and supplemented monopyrroles to tripyrrolic compounds. Subsequent semisynthesis provided the hydroxylated prodiginine. The prodiginines caused reduced infectiousness of
for
plants resulting from impaired motility and stylet thrusting, providing the first insights on the mode of action in this context. Furthermore, the combined application with rhamnolipids was assessed for the first time and found to be more effective against nematode parasitism than the individual compounds. To obtain, for instance, 50% nematode control, it was sufficient to apply 7.8 μM hydroxylated prodiginine together with 0.7 μg/ml (~ 1.1 μM) di-rhamnolipids, which corresponded to
¼ of the individual EC
values. In summary, a hybrid synthetic route toward a hydroxylated prodiginine was established and its effects and combinatorial activity with rhamnolipids on plant-parasitic nematode
are presented, demonstrating potential application as antinematodal agents. Graphical Abstract.
Poly(ethylene glycol) (PEG) is widely employed for passivating nanoparticle (NP) surfaces to prolong blood circulation and enhance localization of NPs to target tissue. However, the immune response ...of PEGylated NPs—including anti-PEG antibody generation, accelerated blood clearance (ABC), and loss of delivery efficacy—is of some concern, especially for treatments that require repeat administrations. Although polyglycerol (PG), which has the same ethylene oxide backbone as PEG, has received attention as an alternative to PEG for NP coatings, the pharmacokinetic and immunogenic impact of PG has not been studied systematically. Here, linear PG, hyperbranched PG (hPG), and PEG-coated polylactide (PLA) NPs with varying surface densities were studied in parallel to determine the pharmacokinetics and immunogenicity of PG and hPG grafting, in comparison with PEG. We found that linear PG imparted the NPs a stealth property comparable to PEG, while hPG-grafted NPs needed a higher surface density to achieve the same pharmacokinetic impact. While linear PG-grafted NPs induced anti-PEG antibody production in mice, they exhibited minimal accelerated blood clearance (ABC) effects due to the poor interaction with anti-PEG immunoglobulin M (IgM). Further, we observed no anti-polymer IgM responses or ABC effects for hPG-grafted NPs.
Almost 30% of all acute myeloid leukemias (AML) are associated with an internal tandem duplication (ITD) in the juxtamembrane domain of FMS-like tyrosine kinase 3 receptor (FLT3). Patients with ...FLT3-ITD mutations tend to have a poor prognosis. MicroRNAs (miRNAs) have a pivotal role in myeloid differentiation and leukemia. MiRNA-155 (MiR-155) was found to be upregulated in FLT3-ITD-associated AMLs. In this study, we discovered that FLT3-ITD signaling induces the oncogenic miR-155. We show in vitro and in vivo that miR-155 expression is regulated by FLT3-ITD downstream targets nuclear factor-κB (p65) and signal transducer and activator of transcription 5 (STAT5). Further, we demonstrate that miR-155 targets the myeloid transcription factor PU.1. Knockdown of miR-155 or overexpression of PU.1 blocks proliferation and induces apoptosis of FLT3-ITD-associated leukemic cells. Our data demonstrate a novel network in which FLT3-ITD signaling induces oncogenic miR-155 by p65 and STAT5 in AML, thereby targeting transcription factor PU.1.
The water exchange process on (CO)(3)Re(H(2)O)(3)(+) (1) was kinetically investigated by (17)O NMR. The acidity dependence of the observed rate constant k(obs) was analyzed with a two pathways model ...in which k(ex) (k(ex)(298) = (6.3 +/- 0.1) x 10(-3) s(-1)) and k(OH) (k(OH)(298)= 27 +/- 1 s(-1)) denote the water exchange rate constants on 1 and on the monohydroxo species (CO)(3)Re(I)(H(2)O)(2)(OH), respectively. The kinetic contribution of the basic form was proved to be significant only at H(+) < 3 x 10(-3) M. Above this limiting H(+) concentration, kinetic investigations can be unambiguously conducted on the triaqua cation (1). The variable temperature study has led to the determination of the activation parameters Delta H(++)(ex) = 90 +/- 3 kJ mol(-1), Delta S(++)(ex) = +14 +/- 10 J K(-1) mol(-1), the latter being indicative of a dissociative activation mode for the water exchange process. To support this assumption, water substitution reaction on 1 has been followed by (17)O/(1)H/(13)C/(19)F NMR with ligands of various nucleophilicities (TFA, Br(-), CH(3)CN, Hbipy(+), Hphen(+), DMS, TU). With unidentate ligands, except Br(-), the mono-, bi-, and tricomplexes were formed by water substitution. With bidentate ligands, bipy and phen, the chelate complexes (CO)(3)Re(H(2)O)(bipy)CF(3)SO(3) (2) and (CO)(3)Re(H(2)O)(phen)(NO(3))(0.5)(CF(3)SO(3))(0.5).H(2)O (3) were isolated and X-ray characterized. For each ligand, the calculated interchange rate constants k'(i) (2.9 x 10(-3) (TFA) < k'(I) < 41.5 x 10(-3) (TU) s(-1)) were found in the same order as the water exchange rate constant k(ex), the S-donor ligands being slightly more reactive. This result is indicative of I(d) mechanism for water exchange and complex formation, since larger variations of k'(i) are expected for an associatively activated mechanism.
The detection of DNA hybridization is of central importance to the diagnosis and treatment of genetic diseases. Due to cost limitations, small and easy-to-handle testing devices are required. ...Electrochemical detection is a promising alternative to evaluation of chip data with optical readout. Independent of the actual readout principle, the hybridization process still takes a lot of time, hampering daily use of these techniques, especially in hospitals or doctor's surgery. Here we describe how direct local electrical heating of a DNA-probe-modified gold electrode affects the surface hybridization process dramatically. We obtained a 140-fold increase of alternating current voltammetric signals for 20-base ferrocene-labeled target strands when elevating the electrode temperature during hybridization from 3 to 48 °C while leaving the bulk electrolyte at 3 °C. At optimum conditions, a target concentration of 500 pmol/L could be detected. Electrothermal regeneration of the immobilized DNA-probe strands allowed repetitive use of the same probe-modified electrode. The surface coverage of DNA probes, monitored by chronocoulometry of hexaammineruthenium(III), was almost constant upon heating to 70 °C. However, the hybridization ability of the probe self-assembled monolayer declined irreversibly when using a 70 °C hybridization temperature. Coupling of heated electrodes and highly sensitive electrochemical DNA hybridization detection methods should enhance detection limits of the latter significantly.
Almost 30% of all acute myeloid leukemias (AML) are associated with an internal tandem duplication (ITD) in the juxtamembrane domain of FMS-like tyrosine kinase 3 receptor (FLT3). Patients with ...FLT3-ITD mutations tend to have a poor prognosis. MicroRNAs (miRNAs) have a pivotal role in myeloid differentiation and leukemia. MiRNA-155 (MiR-155) was found to be upregulated in FLT3-ITD-associated AMLs. In this study, we discovered that FLT3-ITD signaling induces the oncogenic miR-155. We show in vitro and in vivo that miR-155 expression is regulated by FLT3-ITD downstream targets nuclear factor-KB (p65) and signal transducer and activator of transcription 5 (STAT5). Further, we demonstrate that miR-155 targets the myeloid transcription factor PU.1. Knockdown of miR-155 or overexpression of PU.1 blocks proliferation and induces apoptosis of FLT3-ITD-associated leukemic cells. Our data demonstrate a novel network in which FLT3-ITD signaling induces oncogenic miR-155 by p65 and STAT5 in AML, thereby targeting transcription factor PU.1. Leukemia (2015) 29, 535-547; doi: 10.1038/leu.2014.231
The bismuth electrode exhibits similar electrochemical properties as most commonly used toxic mercury electrode and represents a suitable, reliable and also environmentally friendly tool for the ...detection of electroactive compounds at negative potentials. A wide operational potential window of the bismuth electrode from −200 mV to −1400 mV (vs. SCE) was found. Bismuth bulk electrodes (BiBE) are very convenient for sensitive adsorptive stripping voltammetric (AdSV) determination of the drug daunomycin in the nmol/L concentration range. In comparison with gold electrodes, the voltammetric signals of daunomycin at the bismuth electrode are higher and very well shaped. An accumulation potential of −0.65 V (vs. SCE) and accumulation time from 2 to 10 min were found to be optimal conditions for the preconcentration of daunomycin on the bismuth electrode surface. The adsorptive stripping response is linear over 100–1000 nmol/L concentration range (for 2 min deposition) and over 10–100 nmol/L concentration range (for 5 min deposition) with a detection limit of 5 nmol/L (for 8 min deposition). Repeatability was characterized by relative standard deviation 7.1% (for 10 measurements). The electrode must be regenerated between two consecutive measurements by polishing on a damp paper or by stirring in 96% ethanol for 5 min.
A new electrically heated carbon paste electrode has been developed for performing adsorptive stripping measurements of trace nucleic acids. Such coupling of electrochemistry at electrically heated ...electrodes with adsorptive constant-current stripping chronopotentiometry offers distinct advantages for trace measurements of nucleic acids. The application of increased temperatures during the deposition step results in dramatic (4−34-fold, depending on temperature applied) enhancement of the stripping signal. Such improvement is attributed to the accumulation step at the heated electrode. Forced thermal convection near the electrode surface facilitates the use of quiescent solutions and hence of ultrasmall volumes. Using an electrode temperature of 32 °C and a quiescent solution during the 1-min accumulation, the response is linear over the 1−8 mg/L range tested, with a detection limit of 0.5 mg/L. Such electrode heating technology offers great promise for various applications involving thermal manipulations of nucleic acids.
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![NF-[kappa]B/STAT5/miR-155 n...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0887-6924/small "NF-[kappa]B/STAT5/miR-155 network targets PU.1 in FLT3-ITD-driven acute myeloid leukemia.(ORIGINAL ARTICLE)(nuclear factor kappa B/FMS-like tyrosine kinase 3 receptor-internal tandem duplication)")
