scholarly journals Characterization of a Novel N-Acylhomoserine Lactonase RmmL from Ruegeria mobilis YJ3

Marine Drugs ◽  
2018 ◽  
Vol 16 (10) ◽  
pp. 370 ◽  
Author(s):  
Xiulei Cai ◽  
Min Yu ◽  
Hu Shan ◽  
Xiaorong Tian ◽  
Yanfen Zheng ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
High Performance ◽  
Vibrio Anguillarum ◽  
Cell Communication ◽  
Quorum Quenching ◽  
Amino Acid Sequence Analysis ◽  
Chromatography Analysis ◽  
Potential Strategy

Gram-negative bacteria utilize N-acylhomoserine lactones (AHLs) as quorum sensing (QS) signaling molecules for intercellular communication. Cell-to-cell communication depends on cell population density, and AHL-dependent QS is related to the production of multiple genes including virulence factors. Quorum quenching (QQ), signal inactivation by enzymatic degradation, is a potential strategy for attenuating QS regulated bacterial infections. Both Gram-positive and -negative bacteria have QQ enzymes that can degrade AHLs. In our previous study, strain Ruegeria mobilis YJ3, isolated from healthy shrimp, showed strong AHLs degradative activity. In the current study, an AHL lactonase (designated RmmL) was cloned and characterized from Ruegeria mobilis YJ3. Amino acid sequence analysis showed that RmmL has a conserved “HXHXDH” motif and clusters together with lactonase AidC that belongs to the metallo-β-lactamase superfamily. Recombinant RmmL could degrade either short- or long-chain AHLs in vitro. High-performance liquid chromatography analysis indicated that RmmL works as an AHL lactonase catalyzing AHL ring-opening by hydrolyzing lactones. Furthermore, RmmL can reduce the production of pyocyanin by Pseudomonas aeruginosa PAO1, while for the violacein and the extracellular protease activities by Chromobacterium violaceum CV026 and Vibrio anguillarum VIB72, no significant reduction was observed. This study suggests that RmmL might be used as a therapeutic agent in aquaculture.

scholarly journals In Vitro Propagation, Huperzine A Content and Antioxidant Activity of Three Genotypic Huperzia serrata

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1112
Author(s):  
Yan Yang ◽  
Liangfang Dai ◽  
Decai Wu ◽  
Limin Dong ◽  
Yisheng Tu ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
High Performance ◽  
In Vitro Propagation ◽  
Huperzine A ◽  
Induction Medium ◽  
Naphthalene Acetic Acid ◽  
Regeneration Rate ◽  
Huperzia Serrata ◽  
Chromatography Analysis

Huperzia serrata is a traditional herb and endangered Chinese medicinal material, which has attracted much attention due to its production of Huperzine A (HupA). In vitro propagation of H. serrata is considered a new way to relieve the resource pressure of H. serrata. In this study, three different genotypic wild H. serrata were used for in vitro propagation. Then, the antioxidant activity and the content of HupA in the regenerated H. serrata were investigated. The results showed the survival rate of the explant was increased to 25.37% when using multiple sterilization processes. The best induction medium for H. serrata was the Schenk and Hildebrandt (SH) medium supplemented with 0.5 mg·L−1 Naphthalene acetic acid (NAA) and 0.1 mg·L−1 2,4-Dichlorophenoxyacetic acid (2,4-D), where the regeneration rate of the explant was to 57.04%. The best proliferation medium was the SH medium with NAA (1.0 mg·L−1), as the biomass of in vitro tissue increased 164.17 ± 0.41 times. High-performance liquid chromatography analysis showed that the in vitro culture of three genotypes could produce HupA and the content of HupA was 53.90–87.17 µg·g−1. The antioxidant experiment showed that the methanol extract of in vitro H. serrata had higher antioxidant activity than that of wild H. serrata. This study provides a reliable in vitro H. serrata culture protocol and laid an important foundation for the antioxidant capacity of the thallus and the content of HupA.

scholarly journals Abnormal physiological properties and altered cell wall composition in Streptococcus pneumoniae grown in the presence of clavulanic acid.

1997 ◽  
Vol 41 (3) ◽  
pp. 504-510 ◽  
Author(s):  
A Severin ◽  
E Severina ◽  
A Tomasz
Keyword(s):  
Streptococcus Pneumoniae ◽  
High Performance ◽  
Biochemical Properties ◽  
Beta Lactam ◽  
Chromatography Analysis ◽  
Peptide Composition ◽  
Increased Sensitivity ◽  
Altered Cell ◽  
Quantitative Changes

Subinhibitory concentrations of clavulanate caused premature induction of stationary-phase autolysis, sensitization to lysozyme, and reductions in the MICs of deoxycholate and penicillin for Streptococcus pneumoniae. In the range of clavulanate concentrations producing these effects, this beta-lactam compound was selectively bound to PBP 3. Cell walls isolated from pneumococci grown in the presence of clavulanate showed increased sensitivity to the hydrolytic action of purified pneumococcal autolysin in vitro. High-performance liquid chromatography analysis of the peptidoglycan isolated from the clavulanate-grown cells showed major qualitative and quantitative changes in stem peptide composition, the most striking feature of which was the accumulation of peptide species carrying intact D-alanyl-D-alanine residues at the carboxy termini. The altered biological and biochemical properties of the clavulanate-grown pneumococci appear to be the consequences of suppressed D,D-carboxypeptidase activity.

CD40 LIGAND MUTATIONS IN X-LINKED IMMUNODEFICIENCY WITH HYPER-IgM

PEDIATRICS ◽  
1994 ◽  
Vol 94 (2) ◽  
pp. 280-280
Author(s):  
Arden Levy ◽  
Andrew Liu
Keyword(s):  
T Cells ◽  
B Cells ◽  
Bacterial Infections ◽  
Point Mutations ◽  
Cell Communication ◽  
Cd40 Ligand ◽  
Research Groups ◽  
Immune Disorder ◽  
Hyper Igm

Purpose of the Studies. Hyper-IgM immunodeficiency is characterized by recurrent bacterial infections, normal or elevated IgM, and markedly decreased IgG, IgA, and IgE. Previous research suggested that the T cells of these patients are defective in their ability to help B cells make functional antibody. CD40 ligand (CD4OL) is a membrane glycoprotein on activated T helper cells and binds the CD40 molecule expressed on B cells, and induces proliferation and immunoglobulin class switching (in conjunction with IL-4). The gene for the CD4OL has been mapped to position q26.3-q27.1 on chromosome X (same as the Hyper-IgM gene and the area of isotype switching). Several research groups sought to determine if the immunodeficiency in Hyper-IgM patients is due to defective CD4OL. Findings. The five papers listed above document the work of different research groups that simultaneously found abnormalities in the CD4OL gene in a total of 16 patients with X-linked Hyper-IgM syndrome. Different mutations of the CD4OL gene have been discovered, including point mutations, deletions, and nonsense sequences. Mutant version of CD4OL taken from Hyper IgM patients were unable to "help" B cells in vitro. Thus, deficient CD40/CD40L interactions between B and T cells results in severely impaired immunity. Restricted CD40L gene expression to T cells may ultimately allow gene therapy as treatment. Reviewers' Comments. A concise editorial by Jean Marx entitled "Cell Communication Failure Leads to Immune Disorder" describes this landmark research and accompanies the Spriggs article in the February 12th issue of Science (pp. 896-897). This discovery may not only lead to treatment of this disorder, but also modification of other less favorable immune responses.

scholarly journals Identification of FadT as a Novel Quorum Quenching Enzyme for the Degradation of Diffusible Signal Factor in Cupriavidus pinatubonensis Strain HN-2

2021 ◽  
Vol 22 (18) ◽  
pp. 9862
Author(s):  
Xudan Xu ◽  
Tian Ye ◽  
Wenping Zhang ◽  
Tian Zhou ◽  
Xiaofan Zhou ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Xanthomonas Campestris ◽  
Cell Communication ◽  
Maximal Activity ◽  
Quorum Quenching ◽  
Site Directed Mutagenesis ◽  
Diffusible Signal Factor ◽  
High Enzymatic Activity ◽  
Xanthomonas Campestris Pv Campestris ◽  
Potential Use

Quorum sensing (QS) is a microbial cell–cell communication mechanism and plays an important role in bacterial infections. QS-mediated bacterial infections can be blocked through quorum quenching (QQ), which hampers signal accumulation, recognition, and communication. The pathogenicity of numerous bacteria, including Xanthomonas campestris pv. campestris (Xcc), is regulated by diffusible signal factor (DSF), a well-known fatty acid signaling molecule of QS. Cupriavidus pinatubonensis HN-2 could substantially attenuate the infection of XCC through QQ by degrading DSF. The QQ mechanism in strain HN-2, on the other hand, is yet to be known. To understand the molecular mechanism of QQ in strain HN-2, we used whole-genome sequencing and comparative genomics studies. We discovered that the fadT gene encodes acyl-CoA dehydrogenase as a novel QQ enzyme. The results of site-directed mutagenesis demonstrated the requirement of fadT gene for DSF degradation in strain HN-2. Purified FadT exhibited high enzymatic activity and outstanding stability over a broad pH and temperature range with maximal activity at pH 7.0 and 35 °C. No cofactors were required for FadT enzyme activity. The enzyme showed a strong ability to degrade DSF. Furthermore, the expression of fadT in Xcc results in a significant reduction in the pathogenicity in host plants, such as Chinese cabbage, radish, and pakchoi. Taken together, our results identified a novel DSF-degrading enzyme, FadT, in C. pinatubonensis HN-2, which suggests its potential use in the biological control of DSF-mediated pathogens.

PREPARATION AND CHARACTERIZATION OF GLYCYRRHETINIC ACID-MODIFIED POLOXAMER 188/CHITOSAN NANOPARTICLES

NANO ◽  
2013 ◽  
Vol 08 (04) ◽  
pp. 1350042 ◽  
Author(s):  
JING WANG ◽  
LI GUO ◽  
LI FANG MA
Keyword(s):  
High Performance ◽  
Drug Loading ◽  
Chitosan Nanoparticles ◽  
Spherical Shape ◽  
Glycyrrhetinic Acid ◽  
Poloxamer 188 ◽  
H Nmr ◽  
Ft Ir

In this paper, we firstly synthesized glycyrrhetinic acid-modified double amino-terminated poloxamer 188 (GA–NH–POLO–NH–GA). The structure of the synthesized compound was confirmed by 1H-NMR and Fourier transform infrared (FT-IR) spectroscopy. Then the nanoparticles composed of GA–NH–POLO–NH–GA/chitosan (GA–NH–POLO–NH–GA/CTS) were prepared by an ionic gelation process. The characterization of the nanoparticles was measured by dynamic light scattering (DLS) and scanning electron microscope (SEM). The results showed that the nanoparticles were well dispersed with a spherical shape and the particle size was distributed between 100 nm and 300 nm. The cytotoxicity based on MTT assay against cells (QGY-7703 cells and L929 cells) showed that the nanoparticles had low toxicity and good biocompatibility. The encapsulation efficiency and drug loading of 5-fluorouracil-loaded nanoparticles (5-FU nanoparticles) were measured by high-performance liquid chromatography (HPLC) and fluorescence spectroscopy, ultraviolet-visible (UV-vis) absorbance. The encapsulation of 5-Fu-loaded CTS nanoparticles was 12.8% and the drug loading was 2.9%, while the encapsulation of 5-Fu-loaded GA–NH–POLO–NH–GA/CTS nanoparticles was 20.9% and the drug loading was 3.36%. The release profile showed that the GA–NH–POLO–NH–GA/CTS nanoparticles were available for sustained release of 5-Fu. The GA–NH–POLO–NH–GA/CTS nanoparticles have a higher affinity to the QGY-7703 cells, so indicated that the GA–NH–POLO–NH–GA/CTS nanoparticles have the capacity of liver-targeting in vitro.

scholarly journals CHARACTERIZATION OF MOLLUSCICIDAL COMPONENT OF Moringa oleifera LEAF AND Momordica charantia FRUITS AND THEIR MODES OF ACTION IN SNAIL Lymnaea acuminata

2013 ◽  
Vol 55 (4) ◽  
pp. 251-259 ◽  
Author(s):  
Aparna Upadhyay ◽  
Vinay K. Singh ◽  
Dinesh K. Singh
Keyword(s):  
High Performance ◽  
Moringa Oleifera ◽  
Momordica Charantia ◽  
Chromatography Analysis ◽  
Leaf Powder ◽  
Fruit Powder ◽  
Lymnaea Acuminata ◽  
Molluscicidal Activity

SUMMARY The molluscicidal activity of the leaf powder of Moringa oleifera and lyophilized fruit powder of Momordica charantia against the snail Lymnaea acuminata was time and concentration dependent. M. oleifera leaf powder (96 h LC50: 197.59 ppm) was more toxic than M. charantia lyophilized fruit powder (96 h LC50: 318.29 ppm). The ethanolic extracts of M. oleifera leaf powder and Momordica charantia lyophilized fruit powder were more toxic than other organic solvent extracts. The 96 h LC50 of the column purified fraction of M. oleifera leaf powder was 22.52 ppm, while that of M. charantia lyophilized fruit powder was 6.21 ppm. Column, thin layer and high performance liquid chromatography analysis show that the active molluscicidal components in M. oleifera leaf powder and lyophilized fruit of M. charantia are benzylamine (96 h LC50: 2.3 ppm) and momordicine (96 h LC50: 1.2 ppm), respectively. Benzylamine and momordicine significantly inhibited, in vivo and in vitro, the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activities in the nervous tissues of L. acuminata. Inhibition of AChE, ACP and ALP activity in the nervous tissues of L. acuminata by benzylamine and momordicine may be responsible for the molluscicidal activity of M. oleifera and M. charantia fruits, respectively.

scholarly journals Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

2015 ◽  
Vol 82 (1) ◽  
pp. 268-278 ◽  
Author(s):  
Yannick Raoul des Essarts ◽  
Jérémy Cigna ◽  
Angélique Quêtu-Laurent ◽  
Aline Caron ◽  
Euphrasie Munier ◽  
...  
Keyword(s):  
Soft Rot ◽  
Potato Production ◽  
Biocontrol Agents ◽  
Bacterial Isolates ◽  
Potato Blackleg ◽  
Content Type ◽  
Potato Plants ◽  
Potential Strategy

ABSTRACTDevelopment of protection tools targetingDickeyaspecies is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against severalDickeyasp. and/orPectobacteriumsp. pathogens. Most of them belonged to thePseudomonasandBacillusgenera.In vitroassays revealed a fitness decrease of the testedDickeyasp. andPectobacteriumsp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated withDickeya dianthicolarevealed that a mix of three biocontrol agents, namely,Pseudomonas putidaPA14H7 andPseudomonas fluorescensPA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission ofD. dianthicolato the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused byD. dianthicolaon potato plants and tubers.

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