scholarly journals Phytotoxin production in Aspergillus terreus is regulated by independent environmental signals

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Markus Gressler ◽  
Florian Meyer ◽  
Daniel Heine ◽  
Peter Hortschansky ◽  
Christian Hertweck ◽  
...  
Keyword(s):  
Aspergillus Terreus ◽  
Response Regulator ◽  
Biological Activities ◽  
Biological Effects ◽  
Response Regulators ◽  
Iron Starvation ◽  
Nitrogen Response ◽  
Plant Seed ◽  
Environmental Signals ◽  
Physiological Relevance

Secondary metabolites have a great potential as pharmaceuticals, but there are only a few examples where regulation of gene cluster expression has been correlated with ecological and physiological relevance for the producer. Here, signals, mediators, and biological effects of terrein production were studied in the fungus Aspergillus terreus to elucidate the contribution of terrein to ecological competition. Terrein causes fruit surface lesions and inhibits plant seed germination. Additionally, terrein is moderately antifungal and reduces ferric iron, thereby supporting growth of A. terreus under iron starvation. In accordance, the lack of nitrogen or iron or elevated methionine levels induced terrein production and was dependent on either the nitrogen response regulators AreA and AtfA or the iron response regulator HapX. Independent signal transduction allows complex sensing of the environment and, combined with its broad spectrum of biological activities, terrein provides a prominent example of adapted secondary metabolite production in response to environmental competition.

Current Advances in the Biological Activity of Polysaccharides in Dendrobium with Intriguing Therapeutic Potential

2018 ◽  
Vol 25 (14) ◽  
pp. 1663-1681 ◽  
Author(s):  
Chun-Ting Lee ◽  
Heng-Chun Kuo ◽  
Yung-Hsiang Chen ◽  
Ming-Yen Tsai
Keyword(s):  
Biological Activity ◽  
Therapeutic Potential ◽  
Biological Activities ◽  
Biological Effects ◽  
Herbal Medicines ◽  
Research Field ◽  
Protective Effects ◽  
Pharmacological Effects ◽  
The Family ◽  
Anti Tumor Activity

The polysaccharides in many plants are attracting worldwide attention because of their biological activities and medical properties, such as anti-viral, anti-oxidative, antichronic inflammation, anti-hypertensive, immunomodulation, and neuron-protective effects, as well as anti-tumor activity. Denodrobium species, a genus of the family orchidaceae, have been used as herbal medicines for hundreds of years in China due to their pharmacological effects. These effects include nourishing the Yin, supplementing the stomach, increasing body fluids, and clearing heat. Recently, numerous researchers have investigated possible active compounds in Denodrobium species, such as lectins, phenanthrenes, alkaloids, trigonopol A, and polysaccharides. Unlike those of other plants, the biological effects of polysaccharides in Dendrobium are a novel research field. In this review, we focus on these novel findings to give readers an overall picture of the intriguing therapeutic potential of polysaccharides in Dendrobium, especially those of the four commonly-used Denodrobium species: D. huoshanense, D. offininale, D. nobile, and D. chrysotoxum.

Nω-Hydroxy-L-arginine and Its Homologues. Chemical and Biological Properties. A Review

2004 ◽  
Vol 69 (3) ◽  
pp. 499-510 ◽  
Author(s):  
Petra Beranová ◽  
Karel Chalupský ◽  
Gustav Entlicher
Keyword(s):  
Inhibitory Activity ◽  
Biological Activities ◽  
Biological Effects ◽  
Biological Properties ◽  
No Synthase ◽  
Point Of View ◽  
No Donor ◽  
Good Substrate ◽  
No Formation ◽  
Vasorelaxant Activity

Nω-Hydroxy-L-arginine (NOHA) is a stable intermediate in NO formation from L-arginine catalyzed by NO synthase (NOS). Apparently, NOHA can be released and serve as a stable reserve NO donor (as a substrate of NOS) or transported and exert its own biological effects. It shows endothelium-dependent as well as endothelium-independent vasorelaxant activity. The latter case indicates that NOHA can be metabolized by pathways independent of NOS. These possibilities are discussed in detail. Of the available NOHA homologues homo-NOHA is a good substrate of NOS while nor-NOHA seems to be a very poor substrate of this enzyme. On the contrary, nor-NOHA exerts arginase inhibitory activity 20 times higher than NOHA whereas homo-NOHA is inactive. Detailed investigation of biological activities of NOHA and its homologues seems to be promising from the pharmacological point of view. A review with 43 references.

scholarly journals Naphthalimide-Containing BP100 Leads to Higher Model Membranes Interactions and Antimicrobial Activity

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 542
Author(s):  
Gustavo Penteado Battesini Carretero ◽  
Greice Kelle Viegas Saraiva ◽  
Magali Aparecida Rodrigues ◽  
Sumika Kiyota ◽  
Marcelo Porto Bemquerer ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Biological Activities ◽  
Biological Effects ◽  
Membrane Surface ◽  
Helical Structure ◽  
Helical Conformation ◽  
Property A ◽  
Cellular Processes ◽  
Double Stranded Dna ◽  
Low Toxicity

In a large variety of organisms, antimicrobial peptides (AMPs) are primary defenses against pathogens. BP100 (KKLFKKILKYL-NH2), a short, synthetic, cationic AMP, is active against bacteria and displays low toxicity towards eukaryotic cells. BP100 acquires a α-helical conformation upon interaction with membranes and increases membrane permeability. Despite the volume of information available, the action mechanism of BP100, the selectivity of its biological effects, and possible applications are far from consensual. Our group synthesized a fluorescent BP100 analogue containing naphthalimide linked to its N-terminal end, NAPHT-BP100 (Naphthalimide-AAKKLFKKILKYL-NH2). The fluorescence properties of naphthalimides, especially their spectral sensitivity to microenvironment changes, are well established, and their biological activities against transformed cells and bacteria are known. Naphthalimide derived compounds are known to interact with DNA disturbing related processes as replication and transcription, and used as anticancer agents due to this property. A wide variety of techniques were used to demonstrate that NAPHT-BP100 bound to and permeabilized zwitterionic POPC and negatively charged POPC:POPG liposomes and, upon interaction, acquired a α-helical structure. Membrane surface high peptide/lipid ratios triggered complete permeabilization of the liposomes in a detergent-like manner. Membrane disruption was driven by charge neutralization, lipid aggregation, and bilayer destabilization. NAPHT-BP100 also interacted with double-stranded DNA, indicating that this peptide could also affect other cellular processes besides causing membrane destabilization. NAPHT-BP100 showed increased antibacterial and hemolytic activities, compared to BP100, and may constitute an efficient antimicrobial agent for dermatological use. By conjugating BP100 and naphthalimide DNA binding properties, NAPHT-BP100 bound to a large extent to the bacterial membrane and could more efficiently destabilize it. We also speculate that peptide could enter the bacteria cell and interact with its DNA in the cytoplasm.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Multivariate Classification of Drugs using Parametric and Nonparametric Machine Learning Models

2020 ◽  
Vol 9 (3) ◽  
pp. 2021-2027
Keyword(s):  
Machine Learning ◽  
Drug Discovery ◽  
Biological Activities ◽  
Biological Effects ◽  
Recursive Feature Elimination ◽  
Drug Candidate ◽  
Learning Models ◽  
Machine Learning Models ◽  
Non Parametric

In pharmaceutical research, traditional drug discovery process is time consuming and expensive, where several compounds are experimentally tested for their biological activities. Series of lab experiments are conducted to analyze newly synthesized drug’s pharmaceutical activities and its biological effects on human. With every new drug discovery, the required clinical properties can be determined using machine learning models and this greatly reduces the experimental cost. This paper explores parametric and non-parametric machine learning models to classify administration properties of drugs and its toxicity. The multinomial classification of drugs was based on their physicochemical and ADMET properties. Balanced data samples were drawn from chEMBL and was pre-processed. Features were reduced using Recursive Feature Elimination and the attributes were ranked based on their importance to reduce highly correlated attributes. The performance of parametric and non-parametric machine learning models was analyzed on cheminformatic data that includes physiochemical, biological and pharmaceutical properties of the drug molecules. Selecting the potent drug candidate along with its administration properties greatly reduces wet lab experimental time and cost. Multiclass classification can be determined efficiently using non-parametric machine learning model. Optimal feature engineering, tuning hyperparameters and adopting hybrid algorithms would result in more accurate predictions in future for cheminformatics data.

scholarly journals Selective Inhibition of Bakuchicin Isolated fromPsoralea corylifoliaon CYP1A in Human Liver Microsomes

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Sun Joo Kim ◽  
Heung Chan Oh ◽  
Youn-Chul Kim ◽  
Gil-Saeng Jeong ◽  
Sangkyu Lee
Keyword(s):  
Human Liver ◽  
Competitive Inhibition ◽  
Biological Activities ◽  
Biological Effects ◽  
Liver Microsomes ◽  
Selective Inhibition ◽  
Human Liver Microsomes ◽  
Inhibition Mechanism ◽  
Inhibitory Effects ◽  
Cyp Isoforms

Bakuchicin is a furanocoumarin isolated fromPsoralea corylifoliaand shows several biological activities. Although there have been studies on the biological effects of bakuchicin, its modulation potency of CYP activities has not been previously investigated. Here, we investigated the inhibitory effects of bakuchicin on the activities of CYP isoforms by using a cocktail of probe substrates in pooled human liver microsomes (HLMs) and human recombinantcDNA-expressedCYP. Bakuchicin strongly inhibited CYP1A-mediated phenacetinO-deethylation with an IC50value of 0.43 μM in HLMs. It was confirmed by human recombinantcDNA-expressedCYP1A1 and CYP1A2 with aKivalue of 0.11 μM and 0.32 μM, respectively. A Lineweaver-Burk plot indicated that the inhibition mechanism of bakuchicin was competitive inhibition. Overall, this is the first study to investigate the potential CYP1A1 and CYP1A2 inhibition associated with bakuchicin and to report its competitive inhibitory effects on HLMs.

Histidine kinases in signal transduction pathways of eukaryotes

1997 ◽  
Vol 110 (10) ◽  
pp. 1141-1145 ◽  
Author(s):  
W.F. Loomis ◽  
G. Shaulsky ◽  
N. Wang
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Signal Transduction Pathways ◽  
Response Regulators ◽  
Histidine Kinases ◽  
Camp Phosphodiesterase ◽  
Wide Range ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Dependent Protein

Autophosphorylating histidine kinases are an ancient conserved family of enzymes that are found in eubacteria, archaebacteria and eukaryotes. They are activated by a wide range of extracellular signals and transfer phosphate moieties to aspartates found in response regulators. Recent studies have shown that such two-component signal transduction pathways mediate osmoregulation in Saccharomyces cerevisiae, Dictyostelium discoideum and Neurospora crassa. Moreover, they play pivotal roles in responses of Arabidopsis thaliana to ethylene and cytokinin. A transmembrane histidine kinase encoded by dhkA accumulates when Dictyostelium cells aggregate during development. Activation of DhkA results in the inhibition of its response regulator, RegA, which is a cAMP phosphodiesterase that regulates the cAMP dependent protein kinase PKA. When PKA is activated late in the differentiation of prespore cells, they encapsulate into spores. There is evidence that this two-component system participates in a feedback loop linked to PKA in prestalk cells such that the signal to initiate encapsulation is rapidly amplified. Such signal transduction pathways can be expected to be found in a variety of eukaryotic differentiations since they are rapidly reversible and can integrate disparate signals.

Synthesis, Characterizations, and Biological Effects Study of Some Quinoline Family

2016 ◽  
pp. 160-196
Author(s):  
Messai Amel
Keyword(s):  
Antibacterial Activity ◽  
Single Crystal ◽  
Biological Activities ◽  
Biological Effects ◽  
Diffusion Method ◽  
Quinoline Derivatives ◽  
Single Crystal Diffraction ◽  
Disk Diffusion Method ◽  
New Approach ◽  
Gram Negative

The objective of this work is the synthesis of new quinoline molecules which could have some biological activities. This chapter reported a new approach to the synthesis of some quinoline derivatives. The Baylis-Hillman reaction on 2-methoxy-3-formyl quinoléines derivatives have applied in order to obtain Baylis-Hillman adducts. The products are characterized by FTIR, NMR and X-ray single crystal diffraction .Also, a study of the antibacterial activity of the 3-(2-chloro quinoline)-3-hydroxy-2 methylene propanonitrile products synthesized have been explored. This assessment is made by using the disk diffusion method. The results showed that the 3-(2'-chloroquinoline)-3-hydroxy-2-methylenepropanonitril derivatives present a good antibacterial effectiveness against the strains tested Gram-positive and no antibacterial potency was observed against the stains Gram-negative used in the test.

scholarly journals Bionic Silk Fibroin Film Promotes Tenogenic Differentiation of Tendon Stem/Progenitor Cells by Activating Focal Adhesion Kinase

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Kang Lu ◽  
Xiaodie Chen ◽  
Hong Tang ◽  
Mei Zhou ◽  
Gang He ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Progenitor Cells ◽  
Silk Fibroin ◽  
Focal Adhesion ◽  
Cell Morphology ◽  
Biological Activities ◽  
Biological Effects ◽  
Tendon Injuries ◽  
Regeneration Ability ◽  
Gene And Protein Expression

Background. Tendon injuries are common musculoskeletal disorders in clinic. Due to the limited regeneration ability of tendons, tissue engineering technology is often used as an effective approach to treat tendon injuries. Silk fibroin (SF) films have excellent biological activities and physical properties, which is suitable for tendon regeneration. The present study is aimed at preparing a SF film with a bionic microstructure and investigating its biological effects. Methods. A SF film with a smooth surface or bionic microstructure was prepared. After seeding tendon stem/progenitor cells (TSPCs) on the surface, the cell morphology, the expression level of tenogenic genes and proteins, and the focal adhesion kinase (FAK) activation were measured to evaluate the biological effect of SF films. Results. The TSPCs on SF films with a bionic microstructure exhibited a slender cell morphology, promoted the expression of tenogenic genes and proteins, such as SCX, TNC, TNMD, and COLIA1, and activated FAK. FAK inhibitors blocked the enhanced expression of tenogenic genes and proteins. Conclusion. SF films with a bionic microstructure may serve as a scaffold, provide biophysical cues to alter the cellular adherence arrangement and cell morphology, and enhance the tenogenic gene and protein expression in TSPCs. FAK activation plays a key role during this biological response process.

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