scholarly journals Spatial structure increases the benefits of antibiotic production in Streptomyces griseus

2018 ◽  
Author(s):  
Sanne Westhoff ◽  
Simon B. Otto ◽  
Aram Swinkels ◽  
Bo Bode ◽  
Gilles P. van Wezel ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Antibiotic Production ◽  
Streptomyces Griseus ◽  
Resistant Mutant ◽  
Cell Number ◽  
Ecological Interactions ◽  
Serial Transfer ◽  
Fitness Effects ◽  
Low Concentrations

AbstractBacteria in the soil compete for limited resources to survive and proliferate. One of the ways they might do this is by producing antibiotics, but the costs of antibiotic production and their low concentrations in soils have led to uncertainty about the role of these natural products for the bacteria that produce them. Here, we examine the fitness effects of streptomycin production by the filamentous soil bacterium Streptomyces griseus and the conditions that modify its ability to invade competitors. Using pairwise competion assays, we first provide direct evidence that streptomycin production enables S. griseus to kill and invade a population of the susceptible species, S. coelicolor, but not a streptomycin-resistant mutant of this species. Next we show that the fitness benefits of streptomycin production are density-dependent, because production scales positively with cell number, and frequency-dependent, with a threshold of invasion of S. griseus at around 1%. Finally, using serial transfer experiments where spatial structure is either maintained or periodically destroyed, we show that spatial structure reduces the threshold frequency of invasion by more than 100-fold, indicating that antibiotic production can permit invasion from extreme rarity. Our results provide clear evidence that streptomycin is both an offensive and defensive weapon that facilitates invasion into occupied habitats and also protects against invasion by competitors. They also indicate that the benefits of antibiotic production rely on ecological interactions occurring at small local scales, suggesting that low antibiotic concentrations in bulk soil are unlikely to be representative of their effective concentrations in nature.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

scholarly journals Effects of Dysbiosis and Dietary Manipulation on the Digestive Microbiota of a Detritivorous Arthropod

2021 ◽  
Vol 9 (1) ◽  
pp. 148
Author(s):  
Marius Bredon ◽  
Elisabeth Depuydt ◽  
Lucas Brisson ◽  
Laurent Moulin ◽  
Ciriac Charles ◽  
...  
Keyword(s):  
Crucial Role ◽  
Structure And Function ◽  
Ecological Interactions ◽  
Dietary Manipulation ◽  
Biotic Factors ◽  
Abiotic And Biotic Factors ◽  
And Function ◽  
Multicellular Organisms ◽  
Over Time

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

scholarly journals Microbiomes attached to fresh perennial ryegrass are temporally resilient and adapt to changing ecological niches

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Sharon A. Huws ◽  
Joan E. Edwards ◽  
Wanchang Lin ◽  
Francesco Rubino ◽  
Mark Alston ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Perennial Ryegrass ◽  
Transcriptional Activity ◽  
Ecological Niches ◽  
Ecological Interactions ◽  
Carbohydrate Degradation ◽  
Host Nutrition ◽  
Role Based ◽  
Insight Into

Abstract Background Gut microbiomes, such as the rumen, greatly influence host nutrition due to their feed energy-harvesting capacity. We investigated temporal ecological interactions facilitating energy harvesting at the fresh perennial ryegrass (PRG)-biofilm interface in the rumen using an in sacco approach and prokaryotic metatranscriptomic profiling. Results Network analysis identified two distinct sub-microbiomes primarily representing primary (≤ 4 h) and secondary (≥ 4 h) colonisation phases and the most transcriptionally active bacterial families (i.e Fibrobacteriaceae, Selemondaceae and Methanobacteriaceae) did not interact with either sub-microbiome, indicating non-cooperative behaviour. Conversely, Prevotellaceae had most transcriptional activity within the primary sub-microbiome (focussed on protein metabolism) and Lachnospiraceae within the secondary sub-microbiome (focussed on carbohydrate degradation). Putative keystone taxa, with low transcriptional activity, were identified within both sub-microbiomes, highlighting the important synergistic role of minor bacterial families; however, we hypothesise that they may be ‘cheating’ in order to capitalise on the energy-harvesting capacity of other microbes. In terms of chemical cues underlying transition from primary to secondary colonisation phases, we suggest that AI-2-based quorum sensing plays a role, based on LuxS gene expression data, coupled with changes in PRG chemistry. Conclusions In summary, we show that fresh PRG-attached prokaryotes are resilient and adapt quickly to changing niches. This study provides the first major insight into the complex temporal ecological interactions occurring at the plant-biofilm interface within the rumen. The study also provides valuable insights into potential plant breeding strategies for development of the utopian plant, allowing optimal sustainable production of ruminants.

scholarly journals Amino Acid Transporter LAT1 (SLC7A5) Mediates MeHg-Induced Oxidative Stress Defense in the Human Placental Cell Line HTR-8/SVneo

2021 ◽  
Vol 22 (4) ◽  
pp. 1707
Author(s):  
Sebastian Granitzer ◽  
Raimund Widhalm ◽  
Martin Forsthuber ◽  
Isabella Ellinger ◽  
Gernot Desoye ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Amino Acid ◽  
De Novo ◽  
Structural Similarity ◽  
Amino Acid Transporter ◽  
Cell Number ◽  
Mehg Exposure ◽  
Acid Transporter ◽  
And Oxidative Stress

The placental barrier can protect the fetus from contact with harmful substances. The potent neurotoxin methylmercury (MeHg), however, is very efficiently transported across the placenta. Our previous data suggested that L-type amino acid transporter (LAT)1 is involved in placental MeHg uptake, accepting MeHg-L-cysteine conjugates as substrate due to structural similarity to methionine. The aim of the present study was to investigate the antioxidant defense of placental cells to MeHg exposure and the role of LAT1 in this response. When trophoblast-derived HTR-8/SVneo cells were LAT1 depleted by siRNA-mediated knockdown, they accumulated less MeHg. However, they were more susceptible to MeHg-induced toxicity. This was evidenced in decreased cell viability at a usually noncytotoxic concentration of 0.03 µM MeHg (~6 µg/L). Treatment with ≥0.3 µM MeHg increased cytotoxicity, apoptosis rate, and oxidative stress of HTR-8/SVneo cells. These effects were enhanced under LAT1 knockdown. Reduced cell number was seen when MeHg-exposed cells were cultured in medium low in cysteine, a constituent of the tripeptide glutathione (GSH). Because LAT1-deficient HTR-8/SVneo cells have lower GSH levels than control cells (independent of MeHg treatment), we conclude that LAT1 is essential for de novo synthesis of GSH, required to counteract oxidative stress. Genetic predisposition to decreased LAT1 function combined with MeHg exposure could increase the risk of placental damage.

scholarly journals Impaired platelet responses to thrombin and collagen in AKT-1–deficient mice

Blood ◽  
2004 ◽  
Vol 104 (6) ◽  
pp. 1703-1710 ◽  
Author(s):  
Juhua Chen ◽  
Sarmishtha De ◽  
Derek S. Damron ◽  
William S. Chen ◽  
Nissim Hay ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Dense Granules ◽  
Fibrinogen Binding ◽  
Downstream Effectors ◽  
Low Concentrations ◽  
Phosphoinositide 3 Kinase ◽  
Deficient Mice ◽  
Granule Release

Abstract We investigated the role of Akt-1, one of the major downstream effectors of phosphoinositide 3-kinase (PI3K), in platelet function using mice in which the gene for Akt-1 had been inactivated. Using ex vivo techniques, we showed that Akt-1-deficient mice exhibited impaired platelet aggregation and spreading in response to various agonists. These differences were most apparent in platelets activated with low concentrations of thrombin. Although Akt-1 is not the predominant Akt isoform in mouse platelets, its absence diminished the amount of total phospho-Akt and inhibited increases in intracellular Ca2+ concentration in response to thrombin. Moreover, thrombin-induced platelet α-granule release as well as release of adenosine triphosphate from dense granules was also defective in Akt-1-null platelets. Although the absence of Akt-1 did not influence expression of the major platelet receptors for thrombin and collagen, fibrinogen binding in response to these agonists was significantly reduced. As a consequence of impaired αIIbβ3 activation and platelet aggregation, Akt-1 null mice showed significantly longer bleeding times than wild-type mice. (Blood. 2004;104:1703-1710)

scholarly journals Role of Phosphopantetheinyl Transferase Genes in Antibiotic Production by Streptomyces coelicolor

2008 ◽  
Vol 190 (20) ◽  
pp. 6903-6908 ◽  
Author(s):  
Ya-Wen Lu ◽  
Adrianna K. San Roman ◽  
Amy M. Gehring
Keyword(s):  
Antibiotic Production ◽  
Streptomyces Coelicolor ◽  
Morphological Development ◽  
Phosphopantetheinyl Transferase ◽  
Calcium Dependent ◽  
Actinorhodin Production

ABSTRACT The phosphopantetheinyl transferase genes SCO5883 (redU) and SCO6673 were disrupted in Streptomyces coelicolor. The redU mutants did not synthesize undecylprodigiosin, while SCO6673 mutants failed to produce calcium-dependent antibiotic. Neither gene was essential for actinorhodin production or morphological development in S. coelicolor, although their mutation could influence these processes.

Obesity and inflammatory bowel disease

2021 ◽  
Vol 75 (1) ◽  
pp. 20-28
Author(s):  
Vladimír Teplan ◽  
Milan Lukáš
Keyword(s):  
Inflammatory Bowel Disease ◽  
Adipose Tissue ◽  
Bowel Disease ◽  
Intestinal Inflammation ◽  
Perioperative Complications ◽  
Overweight And Obesity ◽  
Special Role ◽  
Low Concentrations ◽  
Inflammatory Bowel

The incidence and prevalence of overweight and obesity has dramatically increased in the last decades and is generally considered to be global pandemics. The incidence of inflammatory bowel disease (IBD) is rising parallel with overweight and obesity. Contrary to a conventional believe, about 15–40% patients with IBD are obese, which can contribute to the development and course of IBD, especially in Crohn’s disease. Although the findings of some cohort studies are still conflicting, recent results indicate a special role of visceral adipose tissue and particularly mesenteric adipose tissue known as creeping fat, leading to intestinal inflammation. The involvement of altered adipocyte function and deregulated production of adipokines such as leptin and adiponectin has been suggested in the pathogenesis of IBD. The emerging role of Western diet and microbiota can also open new possibilities in IBD management. The effect of obesity on the IBD-related therapy remains to be studied. The finding that obesity results in suboptimal response to the therapy, potentially promoting rapid clearance of biologic agents and thus leading to their low concentrations, has a great importance. Obesity also makes IBD colorectal surgery technically challenging and might increase a risk of perioperative complications.

The Role of Factor XI in a Dilute Thromboplastin Assay of Extrinsic Coagulation Pathway

2001 ◽  
Vol 85 (06) ◽  
pp. 1055-1059 ◽  
Author(s):  
Shilong Xiong ◽  
Xiaofan He ◽  
Fayi Liu ◽  
Jianzhong Han ◽  
Juncheng Li ◽  
...  
Keyword(s):  
Blood Coagulation ◽  
Platelet Rich Plasma ◽  
Critical Role ◽  
Extrinsic Pathway ◽  
Thrombin Inhibition ◽  
Normal Plasma ◽  
Low Concentrations ◽  
Plasma Depletion ◽  
Coagulation Pathway

SummaryBlood coagulation has been thought to be composed of both intrinsic and extrinsic pathways. Recent evidence strongly supports the critical role of the extrinsic pathway in the initiation of blood coagulation. This investigation established an assay that examines the role of FXI in the thromboplastin-initiated (extrinsic) coagulation based on this new concept. Plasma clotting times were measured at different concentrations of thromboplastin with activated FXII inhibited (FXIIa-inhibited Diluted Thromboplastin Time, FXIIaiDTT). Only at low concentrations of thromboplastin was FXIIaiDTT of FXI-deficient plasma significantly prolonged than that of normal plasma. Depletion of FXI from normal plasma prolonged its FXIIaiDTT and replenishment of FXI shortened it. FXIIaiDTTs of both FVIII-deficient and FIX-deficient plasma were remarkably prolonged, and addition of normal plasma dose-dependently shortened it. Furthermore, earlier α-thrombin inhibition was directly correlated with decreasing FXa generation. The amount of FXa production was: platelet-rich plasma > platelet-poor plasma > FXI-deficient plasma. Therefore, our findings from the FXIIaiDTT assays not only support the critical role of extrinsic pathway in blood coagulation initiation, but also demonstrate the importance of FXI as an amplifier of thrombin generation in thromboplastin-initiated coagulation.

scholarly journals The role of bound potassium ions in the hydrolysis of low concentrations of adenosine triphosphate by preparations of membrane fragments from ox brain cerebral cortex

1970 ◽  
Vol 120 (1) ◽  
pp. 15-24 ◽  
Author(s):  
P. S. G. Goldfarb ◽  
R. Rodnight
Keyword(s):  
Potassium Chloride ◽  
Magnesium Chloride ◽  
Adenosine Triphosphatase ◽  
Time Course ◽  
Atp Hydrolysis ◽  
Protein Ratio ◽  
Low Concentrations ◽  
Hydrolysis Of ◽  
Emission Flame

1. The intrinsic Na+, K+, Mg2+ and Ca2+ contents of a preparation of membrane fragments from ox brain were determined by emission flame photometry. 2. Centrifugal washing of the preparation with imidazole-buffered EDTA solutions decreased the bound Na+ from 90±20 to 24±12, the bound K+ from 27±3 to 7±2, the bound Mg2+ from 20±2 to 3±1 and the bound calcium from 8±1 to <1nmol/mg of protein. 3. The activities of the Na++K++Mg2+-stimulated adenosine triphosphatase and the Na+-dependent reaction forming bound phosphate were compared in the unwashed and washed preparations at an ATP concentration of 2.5μm (ATP/protein ratio 12.5pmol/μg). 4. The Na+-dependent hydrolysis of ATP as well as the plateau concentration of bound phosphate and the rate of dephosphorylation were decreased in the washed preparation. The time-course of formation and decline of bound phosphate was fully restored by the addition of 2.5μm-magnesium chloride and 2μm-potassium chloride. Addition of 2.5μm-magnesium chloride alone fully restored the plateau concentration of bound phosphate, but the rate of dephosphorylation was only slightly increased. Na+-dependent ATP hydrolysis was partly restored with 2.5μm-magnesium chloride; addition of K+ in the range 2–10μm-potassium chloride then further restored hydrolysis but not to the control rate. 5. Pretreatment of the washed preparation at 0°C with 0.5nmol of K+/mg of protein so that the final added K+ in the reaction mixture was 0.1μm restored the Na+-dependent hydrolysis of ATP and the time-course of the reaction forming bound phosphate. 6. The binding of [42K]potassium chloride by the washed membrane preparation was examined. Binding in a solution containing 10nmol of K+/mg of protein was linear over a period of 20min and was inhibited by Na+. Half-maximal inhibition of 42K+-binding required a 100-fold excess of sodium chloride. 7. It was concluded (a) that a significant fraction of the apparent Na+-dependent hydrolysis of ATP observed in the unwashed preparation is due to activation by bound K+ and Mg2+ of the Na++K++Mg2+-stimulated adenosine triphosphatase system and (b) that the enzyme system is able to bind K+ from a solution of 0.5μm-potassium chloride.

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