scholarly journals Contrasting Effects of Environmental Concentrations of Sulfonamides on Microbial Heterotrophic Activities in Freshwater Sediments

2021 ◽  
Vol 12 ◽  
Author(s):  
Stéphane Pesce ◽  
Laura Kergoat ◽  
Laurianne Paris ◽  
Loren Billet ◽  
Pascale Besse-Hoggan ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Surface Sediments ◽  
Temporal Dynamics ◽  
River Sediments ◽  
Transient Effects ◽  
High Concentration ◽  
Environmental Concentrations ◽  
Natural Stream ◽  
Measured Activity ◽  
Stimulation Of

The sulfonamide antibiotics sulfamethoxazole (SMX) and sulfamethazine (SMZ) are regularly detected in surface sediments of contaminated hydrosystems, with maximum concentrations that can reach tens of μg kg–1 in stream and river sediments. Little is known about the resulting effects on the exposed benthic organisms. Here we investigated the functional response of stream sediment microbial communities exposed for 4 weeks to two levels of environmentally relevant concentrations of SMX and SMZ, tested individually. To this end, we developed a laboratory channel experiment where natural stream sediments were immersed in water contaminated with nominal environmental concentrations of 500 and 5,000 ng L–1 of SMX or SMZ, causing their accumulation in surface sediments. The mean maximum concentrations measured in the sediment (about 2.1 μg SMX kg–1 dw and 4.5 μg SMZ kg–1 dw) were consistent with those reported in contaminated rivers. The resulting chronic exposure had various effects on the functional potential of the sediment microbial communities, according to the substance (SMX or SMZ), the type of treatment (high or low) and the measured activity, with a strong influence of temporal dynamics. Whereas the SMZ treatments resulted in only transient effects on the five microbial activities investigated, we observed a significant stimulation of the β-glucosidase activity over the 28 days in the communities exposed to the high concentration of SMX. Together with the stimulation of aerobic respiration at low SMX concentrations and the reduced concentration observed in the last days, our results suggest a potential biodegradation of sulfonamides by microbial communities from sediments. Given the key functional role of surface sediment microbial communities in streams and rivers, our findings suggest that the frequently reported contamination of sediments by sulfonamides is likely to affect biogeochemical cycles, with possible impact on ecosystem functioning.

scholarly journals Effects of Macrofaunal Recolonization on Biogeochemical Processes and Microbiota—A Mesocosm Study

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1599
Author(s):  
Annika Fiskal ◽  
Aixala Gaillard ◽  
Sebastien Giroud ◽  
Dejan Malcic ◽  
Prachi Joshi ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Bottom Water ◽  
Surface Sediments ◽  
Sediment Cores ◽  
Lake Basin ◽  
Sediment Properties ◽  
Chironomid Larvae ◽  
Sediment Reworking ◽  
Mesocosm Experiments ◽  
Tubificid Worms

Macroinvertebrates are widespread in lake sediments and alter sedimentary properties through their activity (bioturbation). Understanding the interactions between bioturbation and sediment properties is important given that lakes are important sinks and sources of carbon and nutrients. We studied the biogeochemical impact of macrofauna on surface sediments in 3-month-long mesocosm experiments conducted using sediment cores from a hypoxic, macrofauna-free lake basin. Experimental units consisted of hypoxic controls, oxic treatments, and oxic treatments that were experimentally colonized with chironomid larvae or tubificid worms. Overall, the presence of O2 in bottom water had the strongest geochemical effect and led to oxidation of sediments down to 2 cm depth. Relative to macrofauna-free oxic treatments, chironomid larvae increased sediment pore water concentrations of nitrate and sulfate and lowered porewater concentrations of reduced metals (Fe2+, Mn2+), presumably by burrow ventilation, whereas tubificid worms increased the redox potential, possibly through sediment reworking. Microbial communities were very similar across oxic treatments; however, the fractions of α-, β-, and γ-Proteobacteria and Sphingobacteriia increased, whereas those of Actinobacteria, Planctomycetes, and Omnitrophica decreased compared to hypoxic controls. Sediment microbial communities were, moreover, distinct from those of macrofaunal tubes or feces. We suggest that, under the conditions studied, bottom water oxygenation has a stronger biogeochemical impact on lacustrine surface sediments than macrofaunal bioturbation.

Endothelium and mechanical responses of isolated monkey pulmonary veins to histamine

1990 ◽  
Vol 259 (4) ◽  
pp. H1032-H1037 ◽  
Author(s):  
T. Matsuki ◽  
T. Ohhashi
Keyword(s):  
Pulmonary Veins ◽  
Dependent Manner ◽  
High Concentration ◽  
Concentration Dependent Manner ◽  
Mechanical Responses ◽  
Relaxing Factor ◽  
Prostaglandin F2 Alpha ◽  
H2 Receptors ◽  
Endothelium Derived Relaxing Factor ◽  
Stimulation Of

Ring strips of monkey pulmonary veins precontracted with a high concentration of prostaglandin F2 alpha (PGF2 alpha) relaxed in a concentration-dependent manner in response to histamine. Treatment with mepyramine and/or famotidine attenuated the relaxation. 2-Pyridylethylamine (2PEA) and dimaprit caused relaxations in the precontracted preparations, which were inhibited by pretreatment with mepyramine and famotidine, respectively. Removal of endothelium reversed the histamine- and 2PEA-induced relaxations to dose-related contractions. On the other hand, the removal had no effect on the dimaprit-induced relaxations, which were significantly reduced by pretreatment with famotidine. Histamine-induced relaxations in the precontracted strips with endothelium in the presence and absence of famotidine were suppressed or abolished by treatment with methylene blue or hemoglobin but were unaffected by aspirin. It may be concluded that histamine-induced relaxation in monkey pulmonary veins precontracted with PGF2 alpha is mediated by H2-receptors in smooth muscle and H1-receptors in endothelium. Also, stimulation of the endothelial H1-receptors liberates an endothelium-derived relaxing factor.

scholarly journals Life on leaves : uncovering temporal dynamics in Arabidopsis' leaf microbiota

2021 ◽  
Author(s):  
Juliana Almario ◽  
Maryam Mahmoudi ◽  
Samuel Kroll ◽  
Matthew Agler ◽  
Aleksandra Placzek ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Photosynthetic Activity ◽  
Temporal Dynamics ◽  
Growing Season ◽  
High Turnover ◽  
Microbial Network ◽  
Stabilization Phase ◽  
Time Patterns ◽  
Microbe Interactions ◽  
Compositional Changes

Leaves are primarily responsible for the plant′s photosynthetic activity. Thus, changes in the phyllosphere microbiota, which includes deleterious and beneficial microbes, can have far reaching effects on plant fitness and productivity. In this context, identifying the processes and microorganisms that drive the changes in the leaf microbiota over a plant′s lifetime is crucial. In this study we analyzed the temporal dynamics in the leaf microbiota of Arabidopsis thaliana, integrating both compositional changes and changes in microbe-microbe interactions via the study of microbial networks. Field-grown Arabidopsis were used to follow leaf bacterial, fungal and oomycete communities, throughout the plant′s growing season (extending from November to March), over three consecutive years. Our results revealed the existence of conserved time patterns, with microbial communities and networks going through a stabilization phase (decreasing diversity and variability) at the beginning of the plant′s growing season. Despite a high turnover in these communities, we identified 19 "core" taxa persisting in Arabidopsis leaves across time and plant generations. With the hypothesis these microbes could be playing key roles in the structuring of leaf microbial communities, we conducted a time-informed microbial network analysis which showed core taxa are not necessarily highly connected network "hubs" and "hubs" alternate with time. Our study shows that leaf microbial communities exhibit reproducible dynamics and patterns, suggesting it could be possible to predict and drive these microbial communities to desired states.

scholarly journals Temporal and spatial dynamics of peat microbiomes in drained and rewetted soils of three temperate peatlands

2020 ◽  
Author(s):  
Haitao Wang ◽  
Micha Weil ◽  
Dominik Zak ◽  
Diana Münch ◽  
Anke Günther ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Community Composition ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Temporal Dynamics ◽  
Salt Water ◽  
Microbial Community Composition ◽  
Gas Emissions

AbstractBackgroundDrainage of high-organic peatlands for agricultural purposes has led to increased greenhouse gas emissions and loss of biodiversity. In the last decades, rewetting of peatlands is on the rise worldwide, to mitigate these negative impacts. However, it remains still questionable how rewetting would influence peat microbiota as important drivers of nutrient cycles and ecosystem restoration. Here, we investigate the spatial and temporal dynamics of the diversity, community composition and network interactions of prokaryotes and eukaryotes, and the influence of rewetting on these microbial features in formerly long-term drained and agriculturally used fens. Peat-soils were sampled seasonally from three drained and three rewetted sites representing the dominating fen peatland types of glacial landscapes in Northern Germany, namely alder forest, costal fen and percolation fen.ResultsCostal fens as salt-water impacted systems showed a lower microbial diversity and their microbial community composition showed the strongest distinction from the other two peatland types. Prokaryotic and eukaryotic community compositions showed a congruent pattern which was mostly driven by peatland type and rewetting. Rewetting decreased the abundances of fungi and prokaryotic decomposers, while the abundance of potential methanogens was significantly higher in the rewetted sites. Rewetting also influenced the abundance of ecological clusters in the microbial communities identified from the co-occurrence network. The microbial communities changed only slightly with depth and over time. According to structural equation models rewetted conditions affected the microbial communities through different mechanisms across the three studied peatland types.ConclusionsOur results suggest that rewetting strongly impacts the structure of microbial communities and, thus, important biogeochemical processes, which may explain the high variation in greenhouse gas emissions upon rewetting of peatlands. The improved understanding of functional mechanisms of rewetting in different peatland types lays the foundation for securing best practices to fulfil multiple restoration goals including those targeting on climate, water, and species protection.

Stimulation of Rhizosphere Microbial Communities During Chemophytostabilization of a Pb-Zn Mine Soil

2013 ◽  
pp. 1013-1022
Author(s):  
María A. Galende ◽  
Lur Epelde ◽  
M T. Gómez-Sagasti ◽  
Oihana Barrutia ◽  
Antonio Hernández ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Mine Soil ◽  
Stimulation Of

Increased activity of carotid sinus baroreceptors by sympathetic stimulation and norepinephrine

1981 ◽  
Vol 240 (4) ◽  
pp. H650-H658 ◽  
Author(s):  
E. Tomomatsu ◽  
K. Nishi
Keyword(s):  
Carotid Sinus ◽  
Sympathetic Innervation ◽  
Sympathetic Nerves ◽  
Nerve Endings ◽  
Discharge Frequency ◽  
Sympathetic Stimulation ◽  
High Concentration ◽  
Excitatory Effect ◽  
Pressure Step ◽  
Stimulation Of

Effects of electrical stimulation of sympathetic nerves to the carotid sinus on the discharge of single active baroreceptor fibers of the rabbit were examined in situ and in functionally isolated carotid sinus preparations with an intact sympathetic innervation under controlled conditions of pressure and temperature. Among 30 single units, 18 units responded to sympathetic stimulation of increasing discharge frequency. The excitatory effect of sympathetic stimulation on baroreceptor activity was not abolished by phentolamine (1 mg/kg iv or 10(-6) g/ml in perfusate). In isolated carotid sinus preparations perfused with Krebs-Henseleit solution, various pressure steps were applied to the sinus, and effects of norepinephrine (NE; 10(-9) and 10(-6) g/ml) on activity of nine single baroreceptor units were examined. In the presence of 10(-9) g/ml NE, discharge frequency of all units significantly increased at a given pressure step when compared with the control, whereas NE at a high concentration (10(-6) g/ml) did not produce significant changes in the discharge frequency. It is concluded that NE released by sympathetic nerve endings most likely acts directly on the baroreceptor nerve endings and sensitizes them.

Effect of Some Flavonic Compounds and Ascorbic Acid on Lactoferrin Stimulation of Erythrocyte Glycolysis and Na+/K+-ATPase Activity

2008 ◽  
Vol 63 (9-10) ◽  
pp. 773-779 ◽  
Author(s):  
Ana Maneva ◽  
Borislava Taleva
Keyword(s):  
Ascorbic Acid ◽  
Atpase Activity ◽  
Specific Binding ◽  
Lactate Production ◽  
Inhibitory Effect ◽  
High Concentration ◽  
Transport Chain ◽  
Strong Inhibitory Effect ◽  
Lactate Formation ◽  
Stimulation Of

The aim of the present study was to assess if some flavonic compounds (quercetin, piceatannol and apigenin) and ascorbic acid could interfere with the Lf stimulatory effect on the erythrocyte function. Quercetin (1.5 μm) and piceatannol (30 μm) showed an additive effect on Lf stimulation of Na+/K+-ATPase when used together with Lf. The enhancement of Lf stimulation on Na+/K+-ATPase in the presence of flavonoids was probably due to their antioxidative properties and/or to their involvement in the erythrocyte signaling. None of the estimated flavonoids showed an effect on Lf stimulation of the lactate production. Quercetin itself enhanced the ATPase activity but did not affect the lactate formation. Apigenin (1.5 μm) enhanced reliably the lactate generation, but it did not exert any effect on the ATPase activity. High concentration of ascorbic acid (60 mm) did not change the Lf stimulatory effect on Na+/K+-ATPase, but decreased the Lf-specific-binding. A significantly strong inhibitory effect on the Lf-specific binding exerted the electron acceptors NAD+ (2 mm) and FAD (2 mm). These effects concern most likely the competition with Lf for electron(s) which is (are) provided from the erythrocyte intercellular electron transport chain(s).

Late signals are required for the stimulation of DNA synthesis in rat mammary fibroblasts by growth factors

1996 ◽  
Vol 16 (3) ◽  
pp. 249-263 ◽  
Author(s):  
Hai-Lan Chen ◽  
Philip S. Rudland ◽  
John A. Smith ◽  
David G. Fernig
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Dna Synthesis ◽  
Maximal Response ◽  
High Concentration ◽  
Initial Concentration ◽  
Maximal Stimulation ◽  
Epidermal Growth ◽  
Lag Period ◽  
Stimulation Of

Maximal stimulation of DNA synthesis in quiescent rat mammary (Rama) 27 fibroblasts is elicited by epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF) 18 h after the initial addition of the growth factors-the ‘lag’ period. At maximally-stimulating concentrations, EGF and bFGF are interchangeable 9 h after their initial addition. When the initial concentration of growth factor is below that required to elicit a maximal response, it is possible to increase the level of DNA synthesis by increasing the concentration of growth factor 9 h after its initial addition. When the initial concentration of growth factor is high, substitution by a lower concentration of growth factor after 9 h allows a greater proportion of cells to synthesize DNA than would be expected from a continuous low dose of growth factor. Similar results are obtained when both the growth factor and its concentration are changed 9 h after the initial addition of growth factor. However, when EGF at a low concentration is substituted for a high concentration of EGF or bFGF the resulting increase in the levels of DNA synthesis is greater when EGF rather than bFGF is added for a second time. The half-life of the growth-stimulatory signals delivered by EGF and by bFGF 9 h after their initial addition is 1–2 h. These results suggest that to stimulate DNA synthesis: (i) EGF or bFGF must deliver a signal(s) continuously; (ii) the initial signals produced by EGF and bFGF are equivalent; (iii) the signals produced between 9–18 h by EGF may be different to those produced by bFGF.

scholarly journals Changes in the sensitivity to glucagon of lipolysis in adipocytes from pregnant and lactating rats

1988 ◽  
Vol 254 (3) ◽  
pp. 661-665 ◽  
Author(s):  
V A Zammit
Keyword(s):  
Adipose Tissue ◽  
The Other ◽  
High Concentration ◽  
Response Curves ◽  
Pregnant Rats ◽  
Adipose Tissue Lipolysis ◽  
The Right ◽  
Peak Lactation ◽  
Stimulation Of

1. Rates of lipolysis were measured at different concentrations of glucagon in adipocytes prepared from parametrial adipose tissue of fed or starved rats in different reproductive states. All experiments were performed in the presence of a high concentration of adenosine deaminase (1 unit/ml). 2. Maximal rates of lipolysis (elicited by 25 nM-glucagon in each instance) were higher in adipocytes from peak-lactating rats than those from pregnant animals in both the fed and starved states. 3. Of adipocytes from fed animals, those from peak-lactating rats were the most sensitive to glucagon, whereas those from late-pregnant and early-lactating rats were 1-2 orders of magnitude less sensitive. 4. Adipocytes from 24 h-starved rats showed a much smaller stimulation of lipolysis by glucagon, making the assessment of sensitivity difficult. Therefore, rates of lipolysis were also measured in the presence of a maximally anti-lipolytic dose of insulin. The presence of insulin did not alter the relative sensitivities to glucagon of adipocytes from fed animals in different reproductive states, although all dose-response curves were shifted to the right. When lipolysis in adipocytes from starved animals was measured in the presence of insulin, it became evident that starvation for 24 h markedly increased the sensitivity of adipocytes from late-pregnant rats to glucagon, but did not affect that of cells from animals in the other reproductive states. 5. It is concluded that the large changes in sensitivity to glucagon that occurred during the reproductive cycle may enable the modulation of adipose-tissue lipolysis in vivo to satisfy the different metabolic requirements of the animal in the transition from pregnancy to peak lactation.

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