Do Exudates Affect Cadmium Speciation and Bioavailability to the Rhizobacterium Sinorhizobium meliloti?

2006 ◽  
Vol 3 (6) ◽  
pp. 424 ◽  
Author(s):  
Karine Dedieu ◽  
Tatiana Iuranova ◽  
Vera I. Slaveykova
Keyword(s):  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Ion Concentration ◽  
Nutrient Cycles ◽  
Free Concentration ◽  
Soil Solutions ◽  
Constitutive Process ◽  
Free Ion ◽  
Cadmium Speciation

Environmental Context. Heavy metals such as cadmium can affect soil microbes and consequently perturb important nutrient cycles resulting in deterioration of the soil fertility. Conversely, soil bacteria might influence cadmium cycling, bioavailability and ecotoxicity by producing exudates such as proteins, polysaccharides and siderophores. These substances are shown to form complexes with cadmium, decreasing the free concentration of cadmium in soil solutions. Abstract. To better understand the role of exudates in cadmium (Cd) speciation and biouptake by the bacterium Sinorhizobium meliloti, the content of various exudate components, including siderophores, proteins and polysaccharides, was quantified in the absence and presence of 10 μM Cd at pH 5.0 and pH 7.0. The obtained results demonstrate that the release of exudates by S. meliloti is a constitutive process rather than one induced by the presence of Cd. Nonetheless, exudates complex Cd and significantly reduce its free ion concentration. Cd bioavailability to S. meliloti was characterized by the amount of adsorbed and intracellular Cd. Adsorbed Cd at pH 5.0 was higher than that at pH 7.0, which is consistent with the higher free Cd concentration and lower amounts of exudates released at that pH. The observed reduction in intracellular Cd at pH 5.0 compared with pH 7.0 was attributed to the prevailing competition between protons and Cd ions for transport sites.

Missing role of groundwater in water and nutrient cycles in the shallow eutrophic lake Kasumigaura, Japan

2008 ◽  
Vol 22 (8) ◽  
pp. 1150-1172 ◽  
Author(s):  
Tadanobu Nakayama ◽  
Masataka Watanabe
Keyword(s):  
Eutrophic Lake ◽  
Nutrient Cycles ◽  
Lake Kasumigaura ◽  
Shallow Eutrophic Lake

scholarly journals Role of Ca2+ in pyruvate dehydrogenase interconversion in brain mitochondria and synaptosomes

1985 ◽  
Vol 227 (1) ◽  
pp. 129-136 ◽  
Author(s):  
R G Hansford ◽  
F Castro
Keyword(s):  
Plasma Membrane ◽  
Steady State ◽  
Pyruvate Dehydrogenase ◽  
Maximal Activity ◽  
Brain Mitochondria ◽  
Ruthenium Red ◽  
Ion Concentration ◽  
Maximal Effect ◽  
State Content

The steady-state content of active (dephospho) pyruvate dehydrogenase (PDHA) of suspensions of coupled rat brain mitochondria oxidizing succinate was found to be markedly increased with increasing free Ca2+ ion concentration of the medium, with a half-maximal effect at 10(-6.43) M Ca2+. Other ions were present in these studies at concentrations appropriate for the cytosol. Depolarization of the plasma membrane of synaptosomes caused an increase in the steady-state content of PDHA, with veratridine giving a larger increase than depolarization by 33 mM-KCl. Values were 68 +/- 1% (n = 13) and 81 +/- 1% (n = 19) of maximal activity, for control incubations and incubations in the presence of 30 microM-veratridine, respectively. Measurements of cytosolic free Ca2+ concentrations ([Ca2+]cyt.) in these suspensions of synaptosomes, with the use of the fluorescent Ca2+-indicator Quin-2, indicated an increase on depolarization, with the change due to 30 microM-veratridine being larger in extent than that due to 33 mM-KCl. Values were 217 +/- 21 nM (n = 15), 544 +/- 48 nM (n = 15) and 783 +/- 75 nM (n = 14) for control, KCl-depolarized and veratridine-depolarized synaptosomes respectively. Experiments in which synaptosomes were treated with Ruthenium Red, an inhibitor of mitochondrial Ca2+ uptake, gave much lower resting contents of PDHA (42 +/- 2% of maximal), but failed to prevent totally an increase on depolarization. Addition of an excess of EGTA to the synaptosomal suspension just before the addition of veratridine resulted in a partial diminution in the response of PDHA content. Parallel studies with Quin-2 indicated no increase in [Ca2+]cyt. on addition of veratridine, under these conditions. Thus an increase in [Ca2+]cyt. forms only a part of the mechanism whereby pyruvate dehydrogenase interconversion responds to depolarization. A decrease in the ATP/ADP ratio may also be important, as inferred from the results of experiments with ouabain, which inhibits the Na+ + K+-dependent ATPase.

Europeanisation and Foreign and Security Policy – Undermining or Rescuing the Nation State?

Politics ◽  
2005 ◽  
Vol 25 (3) ◽  
pp. 175-190 ◽  
Author(s):  
Claudia Major
Keyword(s):  
Security Policy ◽  
Political System ◽  
National Level ◽  
Nation States ◽  
Constitutive Process ◽  
Foreign And Security Policy ◽  
Policy Fields ◽  
Intergovernmental Policy ◽  
The Eu

The article aims to explore the utility of Europeanisation as a concept to grasp the interactions between national and European levels. The article illustrates how the EU impacts on the national level of policy, polity and the politics of Member States and assesses how the role of nation states within the European political system has changed as a result. First, the existing definitions of Europeanisation are critically assessed, contextualised and delimited. Initially developed for communitised policy areas in the first pillar, Europeanisation is defined as an interactive, ongoing and mutually constitutive process of ‘Europeanising’ and ‘Europeanised’ countries, linking national and European levels. Defining Europeanisation as ‘domestic change’, the article then discusses mechanisms, objects and forms, as well as the criteria and conditions of change. The article subsequently seeks to clarify the validity of the Europeanisation concept in capturing the increasing interwovenness of national and European spheres in intergovernmental policy fields situated in the second pillar of the EU, that is, foreign and security policy. Inherent methodological challenges, mainly due to the deficient delimitation of Europeanisation and the intergovernmental character of this policy field are discussed as well as the particularities of its applicability in this unique policy area.

BENEFITS OF NITROGENFIXATION TO THE NITROGENFIXING BACTERIA

2021 ◽  
pp. 42-43
Author(s):  
Shriya Phadnis
Keyword(s):  
Soil Bacteria ◽  
Agricultural Sector ◽  
Nitrogen Starvation ◽  
Review Article ◽  
Symbiotic Association ◽  
Symbiotic Relationship ◽  
Enzymatic Conversion ◽  
Mutualistic Symbiosis ◽  
Biological Nitrogen

The state of some plants being deprived from the availability of nitrogen causing nitrogen starvation leads to the phenomenon of Biological Nitrogen Fixation . Microorganisms are employed to enhance the availability of nitrogen to these plants. The major N2 - xing systems involve the symbiotic association between rhizobia soil bacteria and legumes. The enzymatic conversion of free nitrogen to ammonia occurs as a part of this symbiotic relationship. The signicant role of this phenomenon is enhancing the fertility of the soil and in the growth of the host plant that would otherwise be nitrogen limiting. This process has fascinated researchers in the agricultural sector for the yield of legume crops. This review article focuses on the benets that Rhizobium earns on being in mutualistic symbiosis with the leguminous plants.

scholarly journals Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

2015 ◽  
Vol 198 (3) ◽  
pp. 521-535 ◽  
Author(s):  
Simon Schäper ◽  
Elizaveta Krol ◽  
Dorota Skotnicka ◽  
Volkhard Kaever ◽  
Rolf Hilker ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Acid Stress ◽  
Second Messenger ◽  
Lifestyle Changes ◽  
Single Domain ◽  
Receptor Protein ◽  
Leguminous Plant ◽  
Content Type

ABSTRACTSinorhizobium melilotiundergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG inS. melilotiRm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation ofN-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of theS. melilotigenespleD,SMb20523,SMb20447,SMc01464, andSMc03178encoding putative DGCs and ofSMb21517encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, anS. melilotistrain that did not produce detectable levels of cdG (cdG0) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. TheSMc01790-SMc01796locus, homologous to theAgrobacterium tumefaciensuppABCDEFcluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility.IMPORTANCEWe present the first systematic genome-wide investigation of the role of 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of anS. melilotistrain unable to produce cdG (cdG0) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility ofS. melilotiand uncovered a single-domain PilZ protein as regulator of motility.

scholarly journals Pengaruh Pemberian Kedelai terhadap Sistem Reproduksi

2019 ◽  
Vol 1 (1) ◽  
pp. 53-60
Author(s):  
Rizky Aprilia Wikayanti ◽  
Andre Parmonangan Panjaitan
Keyword(s):  
Menstrual Cycle ◽  
Reproductive System ◽  
Experimental Studies ◽  
Review Literature ◽  
Follicular Phase ◽  
Free Concentration ◽  
Human Reproductive ◽  
17Β Estradiol ◽  
Lh Secretion

Kedelai merupakan tanaman Leguminoceae, yang mengandung senyawa isoflavon. Struktur kimianya menyerupai 17β-estradiol yang memiliki kemampuan untuk berikatan dengan reseptor estrogen yang dapat berpengaruh terhadap sistem reproduksi manusia. Tujuan literatur review ini untuk mengetahui efek kedelai terhadap sistem reproduksi manusia. Metode yang digunakan adalah metode literatur review dari 50 artikel PubMed NCBI, Elsevier dan BMJ Journal yang diperoleh hanya 38 artikel yang digumakan dari tahun 2000 sampai dengan tahun 2018. Berbagai penelitian eksperimental yang dilakukan menunjukkan bahwa kedelai memiliki efek terhadap sistem reproduksi manusia. Kedelai dapat menyebabkan sekresi FSH, sekresi LH menurun dan meningkatkan konsentrasi estradiol bebas. Penurunan FSH dan LH dapat menyebabkan gangguan dalam siklus menstruasi terutama pada fase folikular dan  ovulasi, jika fase folikular terganggu maka siklus menstruasi akan menjadi  tidak teratur. Selain itu fitoestrogen yang terkandung dalam kedelai diketahui dapat menghambat 17-β hidroksisteroidoksidoreduktase sehingga mengakibatkan penurunan kadar testosteron.   Kata kunci: kedelai, manusia, reproduksi   THE ROLE OF SOYBEAN FOR REPRODUCTIVE SYSTEM   ABSTRACT Soybean is a Leguminoceae plant, which contains isoflavone compounds. Its chemical structure resembles 17β-estradiol which has ability to bind to estrogen receptors which can affect the human reproductive system. The purpose of this review literature is to determine the effect of soy on the human reproductive system. Using research articles and books related to the effect of soy on the reproductive system from 2000 to 2018. Various experimental studies conducted showed that soy has an effect on the human reproductive system. Soy can cause FSH secretion, decreased LH secretion and increasing the free concentration of estradiol. Decreased FSH and LH can cause disruption in the menstrual cycle, especially in the follicular phase and ovulation, if the follicular phase is disrupted then the menstrual cycle will become irregular. In addition, phytoestrogens contained in soy are known to inhibit 17-β hydroxysteroidoxidoreductase, resulting in a decrease in testosterone levels.   Keywords : human, reproductive, soybean

The Role of Viruses in the Phytobiome

2018 ◽  
Vol 5 (1) ◽  
pp. 93-111 ◽  
Author(s):  
James E. Schoelz ◽  
Lucy R. Stewart
Keyword(s):  
Soil Bacteria ◽  
Plant Viruses ◽  
Plant Health ◽  
Plant Interactions ◽  
Current Information ◽  
Virus Interactions ◽  
The Impact ◽  
Review Current

Viruses are an important but sequence-diverse and often understudied component of the phytobiome. We succinctly review current information on how plant viruses directly affect plant health and physiology and consequently have the capacity to modulate plant interactions with their biotic and abiotic environments. Virus interactions with other biota in the phytobiome, including arthropods, fungi, and nematodes, may also impact plant health. For example, viruses interact with and modulate the interface between plants and insects. This has been extensively studied for insect-vectored plant viruses, some of which also infect their vectors. Other viruses have been shown to alter the impacts of plant-interacting phytopathogenic and nonpathogenic fungi and bacteria. Viruses that infect nematodes have also recently been discovered, but the impact of these and phage infecting soil bacteria on plant health remain largely unexplored.

The coral reef-dwelling Peneroplis spp. shows calcification resilience to ocean acidification conditions - results from culture experiments

2021 ◽  
Author(s):  
Laurie Charrieau ◽  
Katsunori Kimoto ◽  
Delphine Dissard ◽  
Beatrice Below ◽  
Kazuhiko Fujita ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Ocean Acidification ◽  
Sea Water ◽  
General Structure ◽  
Ion Concentration ◽  
Large Benthic Foraminifera ◽  
Carbonate Ion ◽  
Short Period

<p>Ocean acidification is a consequence of current anthropogenic climate changes. The concomitant decrease in pH and carbonate ion concentration in sea water may have severe impacts on calcifying organisms. Coral reefs are among the first ecosystems recognized vulnerable to ocean acidification. Within coral reefs, large benthic foraminifera (LBF) are major calcium carbonate producers.</p><p>The aim of this study was to evaluate the effects of varying pH on survival and calcification of the symbiont-bearing LBF species <em>Peneroplis</em> spp. We performed culture experiments to study their resistance to ocean acidification conditions, as well as their resilience once placed back under open ocean pH (7.9).</p><p>After three days, small signs of test decalcification were observed on specimens kept at pH 7.4, and severe test decalcification was observed on specimens kept at pH 6.9, with the inner organic lining clearly appearing. After 32 days under pH 7.4, similar strongly decalcified specimens were observed. All the specimens were alive at the end of the experiment. This result demonstrates the resistance of <em>Peneroplis </em>spp. to an acidified pH, at least on a short period of time.</p><p>After being partially decalcified, some of the living specimens were placed back at pH 7.9. After one month, the majority of the specimens showed recalcification features, mostly by addition of new chambers. The trace elements concentrations of the newly formed chambers were analysed by LA-ICPMS. Interestingly, more chambers were added when food was given, which highlights the crucial role of energy source in the recalcification process. Moreover, the newly formed chambers were most of the time abnormal, and the general structure of the tests was altered, with potential impacts on reproduction and in situ survival. In conclusion, if symbiont-bearing LBF show some resistance and resilience to lowered pH conditions, they will remain strongly affected by ocean acidification.</p>

scholarly journals Strain-rate enhancement at Dye 3, Greenland

1999 ◽  
Vol 45 (150) ◽  
pp. 338-345 ◽  
Author(s):  
Throstur Thorsteinsson ◽  
E. D. Waddington ◽  
K. C. Taylor ◽  
R. B. Alley ◽  
D. D. Blankenship
Keyword(s):  
Crystal Size ◽  
Ice Sheets ◽  
Ion Concentration ◽  
Strain Rates ◽  
Anisotropic Flow ◽  
Enhancement Factors ◽  
Measured Strain ◽  
Soluble Ion ◽  
Flow Laws

AbstractIce at depth in ice sheets can be softer in bed-parallel shear than Glen’s flow law predicts. For example, at Dye 3, Greenland, enhancement factors of 3 4 are needed in order to explain the rate of borehole tilting Previous authors have identified crystal fabric as the dominant contributor, but the role of impurities and crystal size is still incompletely resolved. Here we use two formulations of anisotropic flow laws for ice (Azuma’s and Sachs’ models) to account for the effects of anisotropy, and show that the measured anisotropy of the ice at Dye 3 cannot explain all the detailed variations in the measured strain rates, the jump in enhancement across the Holocene–Wisconsin boundary is larger than expected from the measured fabrics alone. Dust and soluble-ion concentration divided by crystal size correlates well with the residual enhancement, indicating that most of the “excess deformation” may be due to impurities or crystal size. While the major features of the deformation at Dye 3 are explained by anisotropy and temperature, results also suggest that further research into the role of impurities and crystal size is warranted.

Role of incoherent pumping and Er 3+ ion concentration on subluminal and superluminal light propagation in Er 3+ -doped YAG crystal

2015 ◽  
Vol 24 (1) ◽  
pp. 014204 ◽  
Author(s):  
Seyyed Hossein Asadpour ◽  
H. Rahimpour Soleimani
Keyword(s):  
Light Propagation ◽  
Ion Concentration
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