Two novel bithienyl fluorobenzamidine derivatives namely, 4-(2,2':5',2''-terthiophen-5-yl)-2-fluorobenzamidine hydrochloride salt (MA-1615), ...5'-(4-amidino-3-fluorophenyl)-2,2'-bithiophene-5-carboxamidine dihydrochloride salt (MA-1740) were synthesized, characterized and their corrosion inhibition properties were evaluated by electrochemical methods for carbon steel (C-steel) in 1 M HCl. Experimental investigations revealed that the inhibition effectiveness of the investigated inhibitors (INHs) by the Tafel polarization method followed the order: MA-1740 (96.9%) > MA-1615 (95.6%), demonstrating higher efficiency than inhibitors of similar structure reported in the literature. The investigated bithiophene derivatives exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of C-steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. UV-Visible spectrometric measurements confirmed a complex formation between the Fe
cation released during the corrosion reactions and inhibitor molecules.
Aims
Comparative genomics analyses indicated that the Flavobacterium columnare genome has unique denitrification genes relative to Flavobacterium psychrophilum and Flavobacterium johnsoniae, ...including nasA (nitrate reductase), nirS (nitrite reductase), norB (nitric oxide reductase) and nosZ (nitrous oxide reductase). The current study determines the roles of nasA, nirS, norB and nosZ in anaerobic growth, nitrate reduction, biofilm formation and virulence.
Methods and Results
Four in‐frame deletion mutants in virulent F. columnare strain 94‐081 were constructed by allelic exchange using pCP29 plasmid. Compared with parent strain 94‐081, FcΔnasA,FcΔnirS and FcΔnosZ mutants did not grow as well anaerobically, whereas the growth of FcΔnorB strain was similar to the parent strain (FcWT). Exogenous nitrate was not significantly consumed under anaerobic conditions in FcΔnasA, FcΔnirS and FcΔnosZ compared to parent strain 94‐081. Under anaerobic conditions, Fc∆nasA, Fc∆norB and Fc∆nosZ formed significantly less biofilm than the wild type strain at 24 and 96 h, but FcΔnirS was not significantly affected. The nitrite reductase mutant FcΔnirS was highly attenuated in catfish, whereas FcΔnasA, FcΔnorB and FcΔnosZ had similar virulence to FcWT.
Conclusions
These results show, for the first time, that denitrification genes enable F. columnare to grow anaerobically using nitrate as an electron acceptor, and nitrite reductase contributes to F. columnare virulence.
Significance and Impact of the Study
These findings indicate potential for F. columnare to grow in nitrate‐rich anaerobic zones in catfish production ponds, and they suggest that a Fc∆nirS strain could be useful as a safe live vaccine if it protects catfish against columnaris disease.
Abstract
We report on the synthesis and characterization of six novel 2,2′-bithiophene-based organic compounds (
3a–c
and
5a–c
) that are designed to serve as co-sensitizers for dye-sensitized solar ...cells (DSSCs) based on TiO
2
. The compounds are linked to various donor and acceptor groups, and we confirm their chemical structures through spectral analyses. Our focus is on enhancing the performance of metal based
N3
, and the compounds were designed to operate at the nanoscale. We performed absorption and fluorescence emission measurements in dimethylformamide (DMF), where one of our compounds
5a
exhibited the longest maximum absorption and maximum emission wavelengths, indicating the significant impact of the para methoxy group as a strong electron-donating group. Our dyes
5a + N3
(η = 7.42%) and
5c + N3
(η = 6.57%) outperformed
N3
(η = 6.16%) alone, where the values of short current density (
J
SC
) and open circuit voltage (
V
OC
) for these two systems also improved. We also investigated the charge transfer resistance at the TiO
2
/dye/electrolyte interface using electrochemical impedance spectroscopy (EIS), which is important in the context of nanotechnology. According to the Nyquist plot, the
5a + N3
cocktail exhibited the lowest recombination rate, resulting in the highest
V
OC
. Our theoretical calculations based on density functional theory (DFT) are also in agreement with the experimental process. These findings suggest that our compounds have great potential as efficient DSSC co-sensitizers. This study provides valuable insights into the design and synthesis of new organic compounds for use as co-sensitizers in DSSCs based on TiO
2
and highlights the potential of these compounds for use in efficient solar energy conversion.
Listeria monocytogenes is a Gram-positive intracellular pathogen that cause listeriosis, a fatal foodborne disease for human and animals. Pathogenesis of L. monocytogenes is tightly controlled by ...transcriptional regulators. Among these regulators, we found the genome of L. monocytogenes F2365 contains seven members of the DeoR-family of regulators. Although some members of the DeoR-family have been studied in several bacteria, its function in L. monocytogenes is unexplored, even though sugar metabolism is crucial for virulence. The goal of the present study was to assess the importance of fruR (LMOF2365_2307), which encodes a DeoR-family transcriptional regulator, in the virulence of L. monocytogenes.
Overlap extension PCR and allelic exchange were used to construct an L. monocytogenes strain lacking fruR (ΔfruR). To determine the role in in vivo and intracellular virulence, mice model challenges and plaque assay in murine L2 fibroblast cell lines were conducted, respectively. Furthermore, RNA-seq analysis were performed to identify upregulation and downregulation of genes due to deletion of fruR.
In the murine model, deletion of fruR severely decreased virulence compared to parent F2365 strain, and constitutive activation of PrfA, a key virulence regulator of L. monocytogenes, did not restore virulence to ΔfruR strain. Moreover, ΔfruR strain was defective for cell-to-cell spread in L2 fibroblast cells. The ΔfruR strain had an increased lag phase compared to F2365 during growth in media with H2O2, suggesting that FruR contributes to survival of L. monocytogenes during oxidative stress. Furthermore, RNA-seq analysis revealed that glycolysis and pentose phosphate pathway (PPP) genes were significantly affected by fruR deletion. In particular, FruR induces expression of genes encoding PPP enzymes and suppresses glycolysis genes. Taken together, these results suggest a novel virulence mechanism whereby FruR upregulates the PPP, and this upregulation is necessary for full protection from oxidative stress.
This study clarifies the role of FruR in controlling L. monocytogenes carbon metabolism and provides a new mechanism allowing metabolic adaptation of L. monocytogenes to oxidative stress and may assist in the development of intervention strategies to control Listeria infection.
Catfish is the largest aquaculture industry in the United States. Edwardsiellosis is considered one of the most significant problems affecting this industry. Edwardsiella piscicida is a newly ...described species within the genus Edwardsiella, and it was previously classified as Edwardsiella tarda. It causes gastrointestinal septicaemia, primarily in summer months, in farmed channel catfish in the south‐eastern United States. In the current study, we adapted gene deletion methods used for Edwardsiella to E. piscicida strain C07‐087, which was isolated from a disease outbreak in a catfish production pond. Four genes encoding structural proteins in the type III secretion system (T3SS) apparatus of E. piscicida were deleted by homologous recombination and allelic exchange to produce in‐frame deletion mutants (EpΔssaV, EpΔesaM, EpΔyscR and EpΔescT). The mutants were phenotypically characterized, and virulence and vaccine efficacy were evaluated. Three of the mutants, EpΔssaV, EpΔyscR and EpΔesaM, were significantly attenuated compared to the parent strain (p < .05), but EpΔescT strain was not. Vaccination of catfish with the four mutant strains (EpΔssaV, EpΔesaM, EpΔyscR and EpΔescT) provided significant protection when subsequently challenged with wild‐type strain. In conclusion, we report methods for gene deletion in E. piscicida and development of vaccine candidates derived from a virulent catfish isolate.
Aims
Using molecular subtyping techniques, Listeria monocytogenes is divided into three major phylogenetic lineages, and a multiplex PCR method can differentiate five L. monocytogenes subgroups: ...1/2a‐3a, 1/2c‐3c, 1/2b‐3b‐7, 4b‐4d‐4e and 4a‐4c. In this study, we conducted genome comparisons and evaluated serotype‐associated genes for their utility as a multiplex PCR‐based method for distinguishing high‐risk serotypes 1/2a and 1/2c in lineage I from low‐risk serotypes 3a and 3c.
Methods and Results
Primer sets were developed that are specific for serotype 1/2c (LMOSLCC2372_0308) and serotype 3a (LMLG_0742). These primers were then tested in a multiplex format with primers specific for serotype 1/2a (flaA) to separate serotypes 1/2a, 1/2c, 3a and 3c using 25 strains of lineage I L. monocytogenes.
Conclusions
Here, for the first time, we report primers specific for L. monocytogenes serotype 1/2c and serotype 3a, and we demonstrate a multiplex PCR method for separating the four serotypes of lineage I L. monocytogenes.
Significance and Impact of the Study
The described multiplex PCR assay consistently showed successful separation of 1/2a and 1/2c strains from 3a and 3c strains. PCR is routinely performed in many diagnostic and epidemiologic investigations for L. monocytogenes, and these primers should increase the feasibility and accessibility of L. monocytogenes serotyping.
Ketogenic diet (KD) is widely used for drug-resistant epilepsy (DRE). The study was designed to evaluate one of the risk factors for development of renal calculi with KD.
Twenty patients with DRE on ...Modified Atkins diet (MAD) were subjected to full history and laboratory investigations, including microscopic urine analysis, urinary calcium after overnight fasting, and calcium/creatinine ratio, as well as pelviabdominal ultrasound. Frequency and severity of seizures assessed by Chalfont severity score were recorded. All assessment measures were repeated after 3 and 6 months of KD therapy.
There were significant reductions in both frequency and severity of seizures, yet 2 patients (10%) developed renal stones after 6 months on KD. Gross hematuria was reported in 1 of those 2 patients (50%), but microscopic hematuria was detected in both patients. The urine calcium and the urine calcium/creatinine ratio were elevated in both patients having renal calculi after 6 months.
KD increases the risk of renal stones with hypercalciuria among the causes. We recommend initiation of prophylactic measures once KD is commenced by maximizing fluid intake and urine alkalinization with regular urinary studies including calcium/creatinine ratio and renal ultrasound for patients with symptoms.
KD has been increasingly used in epilepsy management and beyond. The potential side effects of such diet should be highlighted while valuing the merits. KD increases the risk of renal stones because of hypercalciuria among other causes. We recommend initiation of prophylactic measures once KD is commenced by maximizing fluid intake and urine alkalinization with estimation of urinary calcium/creatinine ratio and renal ultrasound in patients with relevant symptoms.
Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC). We have shown recently that tricarboxylic acid cycle (TCA) and one-carbon (C1) ...metabolism are involved in E. ictaluri pathogenesis. However, the effect of multiple mutations in these pathways is unknown. Here, we report four novel E. ictaluri mutants carrying double gene mutations in TCA cycle (EiΔmdhΔsdhC, EiΔfrdAΔsdhC), C1 metabolism (EiΔglyAΔgcvP), and both TCA and C1 metabolism pathways (EiΔgcvPΔsdhC). In-frame gene deletions were constructed by allelic exchange and mutants’ virulence and vaccine efficacy were evaluated using in vivo bioluminescence imaging (BLI) as well as end point mortality counts in catfish fingerlings. Results indicated that all the double gene mutants were attenuated compared to wild-type (wt) E. ictaluri. There was a 1.39-fold average reduction in bioluminescence, and hence bacterial numbers, from all the mutants except for EiΔfrdAΔsdhC at 144h post-infection. Vaccination with mutants was very effective in protecting channel catfish against subsequent infection with virulent E. ictaluri 93-146 strain. In particular, immersion vaccination resulted in complete protection. Our results provide further evidence on the importance of TCA and C1 metabolism pathways in bacterial pathogenesis.
Novel dyes
F1-3
based on bichalcophene-pyrimidine-2,4,6-trione derivatives with dual anchoring were developed, synthesized, and evaluated as sensitizers and co-sensitizers for dye-sensitized solar ...cells (DSSCs).
F1
displayed the best DSSC performance (
η,
PCE = 4.41%) and the highest photovoltaic parameters, which were as follows: current density,
J
SC
= 10.66 mA cm
−2
, photovoltage,
V
OC
= 0.654 V, and fill factor, FF = 64.3%. These findings can be ascribed to
F1
’s superior optical and electrochemical characteristics when compared to other structures such as
F2
and
F3
. Interestingly, devices that rely on the
F1 + N-719
co-sensitization approach had greater photocurrent and photovoltage than the standard
N-719
dye, generating a power conversion efficiency (PCE) of 9.97%. This improved performance was mostly due to a higher
J
SC
value of 23.28 mA cm
−2
for the dye
F1
and a maximum molar extinction coefficient in the 350–550 nm region, which enhanced the light-harvesting capacity of the
N-719
dye.
The new digital technologies have become an effective tool for researchers in different fields. Historians and archaeologists who are studying Greek and Roman Libya have benefited from technical ...developments in presenting different kinds of data, particularly relating to the epigraphy and toponymy of Libya. They have recently published several resources, and are working on more. This study presents the story of how scholars have collected a variety of Libyan heritage materials and published them online; the account makes it clear that these digital projects are the result of extensive and ongoing collaboration between researchers from different countries, including Libya. They have worked together, and are still working to produce valuable online corpora of inscriptions alongside the Heritage Gazetteer of Libya which records names used at different times, and in a variety of languages, of heritage sites. We also discuss plans for further improving the accessibility of these materials, and encouraging their wider use. أصبحت التقنيات الرقمية الحديثة أداة فعالة للباحثين في مجالات مختلفة، وقد استفاد المؤرخون والآثاريون، المهتمون بتاريخ ليبيا وآثارها في الفترتين الإغريقية والرومانية، من التطورات التقنية لتقديم بيانات (data) مختلفة وخاصة تلك المتعلقة بالنقوش ودراسة مسميات المواقع الأثرية بليبيا. قام هؤلاء حديثاً بنشر مصادر متعددة، معضمها لنقوش، ولا يزال العمل مستمر على أعمال أخرى. توضح هذه الدراسة الكيفية التي تمكن خلالها الباحثون من جمع مواد متنوعة من التراث الليبي، ثم نشرها لتكون متاحة للجميع على الشبكة العنكبوتية (الإنترنت). تُبين هذه الورقة بشكل جلي أن هذه المشاريع الرقمية جاءت نتيجة تعاون مكثف ودؤوب بين باحثين من بلدان عِدَّة بما فيها ليبيا. حيث عملوا معاً ولا يزالوا مستمرين في تقديم مجموعة قيمة للنقوش الإغريقية واللاتينية، بالإضافة إلى فهرس جغرافي يسجل اسماء لمواقع أثرية اُستخدمت في حقب مختلفة وسُميت بلغات متعددة. كما ناقشت هذه الورقة خططاً من شأنها تطويرإمكانية الوصول لهذه المواد التراثية وتشجيع استخدامها على نطاق موسع .
PDF
