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Sample records for 3h-gaba uptake sites

  1. Distribution of 3H-GABA uptake sites in the nematode Ascaris

    SciTech Connect

    Guastella, J.; Stretton, A.O. )

    1991-05-22

    The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, located at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.

  2. Uptake and release of [3H]GABA by growth cones isolated from neonatal rat brain.

    PubMed

    Gordon-Weeks, P R; Lockerbie, R O; Pearce, B R

    1984-11-23

    A subcellular fraction highly enriched in neuronal growth cones was isolated from 5-day-old rat forebrain by a recently described method. The growth cone fraction was shown to have a sodium- and temperature-dependent, high-affinity (Km = 4.4 microM) uptake system for [3H]GABA. Electron microscopic autoradiography confirmed that this uptake was into growth cones since only these structures were heavily labelled with silver grains. High potassium induced the release of newly accumulated [3H]GABA from the growth cone fraction, about half of which was Ca2+-dependent. The presence of uptake and release systems for GABA in growth cones may simply reflect the development of growth cones into nerve terminals. Alternatively, these observations may indicate a role for neurotransmitter release in synaptogenesis.

  3. Centrifuge-induced hypergravity: [ 3H]GABA and L-[ 14C]glutamate uptake, exocytosis and efflux mediated by high-affinity, sodium-dependent transporters

    NASA Astrophysics Data System (ADS)

    Borisova, T. A.; Himmelreich, N. H.

    The effects of centrifuge-induced hypergravity on the presynaptic events have been investigated in order to provide further insight into regulation of glutamate and GABA neurotransmission and correlation between excitatory and inhibitory responses under artificial gravity conditions. Exposure of animals to hypergravity (centrifugation of rats at 10 G for 1 h) has been found to cause changes in the synaptic processes of brain, in particular neurotransmitter release and uptake in rat brain synaptosomes. Hypergravity loading resulted in more than two-fold enhancement of GABA transporter activity ( Vmax increased from 1.4 ± 0.3 nmol/min/mg of protein in the control group to 3.3 ± 0.59 nmol/min/mg of protein for the animals exposed to hypergravity ( P ⩽ 0.05)). The maximal velocity of L-[ 14C]glutamate uptake decreased from 12.5 ± 3.2 to 5.6 ± 0.9 nmol/min/mg of protein under artificial gravity conditions. Depolarization-evoked exocytotic release of the neurotransmitters has also changed in response to hypergravity. It increased for GABA (7.2 ± 0.54% and 11.74 ± 1.2% of total accumulated label for control and hypergravity, respectively ( P ⩽ 0.05)), but reduced for glutamate (14.4 ± 0.7% and 6.2 ± 1.9%, for control and hypergravity, respectively). Thus, comparative analysis of the neurotransmitter uptake and release has demonstrated that short-term centrifuge-induced 10 G hypergravity loading intensified inhibitory and attenuated excitatory processes in nerve terminals. The activation or reduction of neurotransmitter uptake appeared to be coupled with similarly directed alterations of the neurotransmitter release.

  4. Regulation of (/sup 3/H)GABA release from strips of guinea pig urinary bladder

    SciTech Connect

    Shirakawa, J.; Taniyama, K.; Iwai, S.; Tanaka, C.

    1988-12-01

    The presence of receptors that regulate the release of gamma-aminobutyric acid (GABA) was studied in strips of the guinea pig urinary bladder. GABA (10(-8)-10(-5) M) and muscimol (10(-8)-10(-5) M), but not baclofen (10(-5) M), reduced the Ca2+-dependent, tetrodotoxin-resistant release of (/sup 3/H)GABA evoked by high K+ from the urinary bladder strips preloaded with (/sup 3/H)GABA. The inhibitory effect of muscimol was antagonized by bicuculline and potentiated by diazepam, clonazepam, and pentobarbital sodium. The potentiating effect of clonazepam was antagonized by Ro 15-1788. Acetylcholine (ACh) inhibited the high K+-evoked release of (/sup 3/H)GABA. The inhibitory effect of ACh was antagonized by atropine sulfate and pirenzepine but not by hexamethonium. Norepinephrine (NE) inhibited the evoked release of (/sup 3/H)GABA. The inhibitory effect of NE was mimicked by clonidine, but not by phenylephrine, and was antagonized by yohimbine but not by prazosin. These results provide evidence that the release of GABA from strips of guinea pig urinary bladder is regulated via the bicuculline-sensitive GABAA receptor, M1-muscarinic, and alpha 2-adrenergic receptors.

  5. Purinergic modulation of [(3)H]GABA release from rat hippocampal nerve terminals.

    PubMed

    Cunha, R A; Ribeiro, J A

    2000-04-27

    The hippocampal GABAergic system is assumed not to be a target for purine modulation. We have now confirmed that neither adenosine A(1) and A(3) receptor nor nucleotide P(2) or P(4) receptor activation modified the K(+)-evoked [(3)H]GABA release from hippocampal synaptosomes. However, activation of adenosine A(2A) receptors with CGS 21680 (10 nM) or HENECA (30 nM) facilitated GABA release by 32% and 21%, respectively. These effects were prevented by the A(2A) antagonist, ZM 241385 (20 nM). A(2A) receptors may activate adenylate cyclase and protein kinase A since CGS 21680 (10 nM) facilitation was partially prevented by 8-bromo-cAMP (1 mM), forskolin (10 microM) and HA-1004 (10 microM). Protein kinase C may also be recruited, since chelerythrine (6 microM) and phorbol-12, 13-didecanoate (250 nM) attenuated CGS 21680 (10 nM) facilitation of [(3)H]GABA release. Omega-agatoxin-IVA (200 nM) occluded CGS 21680 facilitation suggesting the involvement of P-type calcium channels. Thus, the adenosine A(2A) receptor system appears to be one of the first presynaptic neuromodulatory systems able to enhance the evoked release of GABA from hippocampal nerve terminals.

  6. gamma-Aminobutyric acidA (GABAA) receptors modulate [3H]GABA release from isolated neuronal growth cones in the rat.

    PubMed

    Lockerbie, R O; Gordon-Weeks, P R

    1985-04-19

    Potassium-induced release of gamma-[3H]aminobutyric acid [( 3H]GABA) from a growth cone-enriched fraction isolated from neonatal rat forebrain was inhibited by the GABA mimetic muscimol in a dose-dependent manner (IC50 15 nM). The GABA antagonist bicuculline completely reversed the effect of muscimol. Bicuculline alone slightly potentiated the K+-induced release of [3H]GABA. Baclofen, a proposed selective agonist for a bicuculline-insensitive GABAB receptor, was found to cause only a slight reduction in the K+-induced release of [3H]GABA. These results are compatible with the presence of a negative feedback mechanism mediated by GABAA receptors for controlling [3H]GABA release from growth cones of the developing rat forebrain.

  7. Autoradiographic analysis of 3H-glutamate, 3H-dopamine, and 3H-GABA accumulation in rabbit retina after kainic acid treatment

    SciTech Connect

    Hampton, C.K.; Redburn, D.A.

    1983-01-01

    We have previously reported that exposure of isolated rabbit retina to 10(-3) M kainic acid produces profound morphological changes in specific retinal neurons (Hampton et al, 1981). We noted specific swelling of horizontal cell bodies and neurites, necrosis of cell bodies in the amacrine and ganglion cell layers, and swelling of elements in the inner plexiform layer. We now report a differential sensitivity to kainic acid of specific subclasses of amacrine cells autoradiographically labeled with 3H-glutamate, 3H-GABA, or 3H-dopamine. Three different effects were observed: (1) Labeling of neurons after incubation in 3H-glutamate was uniformly reduced while labeling of glia was much less affected. (2) The accumulation of 3H-dopamine was also decreased by kainic acid in two of the three labeled bands of the inner plexiform layer. The outermost labeled band was insensitive to kainic acid at the highest concentration tested (10(-2) M). These findings provide a basis for the subclassification of dopaminergic amacrine cells into at least two subclasses based on their sensitivity to kainic acid. (3) Kainic acid caused a dramatic increase in the labeling of GABAergic amacrine cell bodies and their terminals. This increased intensity may reflect a compensatory increase in uptake activity in response to kainic acid-induced depletion of endogenous GABA stores. These results confirm the highly toxic nature of kainic acid and demonstrate a high degree of specificity and complexity in its action in the retina.

  8. Histamine H3 receptor activation counteracts adenosine A2A receptor-mediated enhancement of depolarization-evoked [3H]-GABA release from rat globus pallidus synaptosomes.

    PubMed

    Morales-Figueroa, Guadalupe-Elide; Márquez-Gómez, Ricardo; González-Pantoja, Raúl; Escamilla-Sánchez, Juan; Arias-Montaño, José-Antonio

    2014-08-20

    High levels of histamine H3 receptors (H3Rs) are found in the globus pallidus (GP), a neuronal nucleus in the basal ganglia involved in the control of motor behavior. By using rat GP isolated nerve terminals (synaptosomes), we studied whether H3R activation modified the previously reported enhancing action of adenosine A2A receptor (A2AR) stimulation on depolarization-evoked [(3)H]-GABA release. At 3 and 10 nM, the A2AR agonist CGS-21680 enhanced [(3)H]-GABA release induced by high K(+) (20 mM) and the effect of 3 nM CGS-21680 was prevented by the A2AR antagonist ZM-241385 (100 nM). The presence of presynaptic H3Rs was confirmed by the specific binding of N-α-[methyl-(3)H]-histamine to membranes from GP synaptosomes (maximum binding, Bmax, 1327 ± 79 fmol/mg protein; dissociation constant, Kd, 0.74 nM), which was inhibited by the H3R ligands immepip, clobenpropit, and A-331440 (inhibition constants, Ki, 0.28, 8.53, and 316 nM, respectively). Perfusion of synaptosomes with the H3R agonist immepip (100 nM) had no effect on K(+)-evoked [(3)H]-GABA release, but inhibited the stimulatory action of A2AR activation. In turn, the effect of immepip was blocked by the H3R antagonist clobenpropit, which had no significant effect of its own on K(+)-induced [(3)H]-GABA release. These data indicate that H3R activation selectively counteracts the facilitatory action of A2AR stimulation on GABA release from striato-pallidal projections.

  9. Histamine H3 Receptor Activation Counteracts Adenosine A2A Receptor-Mediated Enhancement of Depolarization-Evoked [3H]-GABA Release from Rat Globus Pallidus Synaptosomes

    PubMed Central

    2014-01-01

    High levels of histamine H3 receptors (H3Rs) are found in the globus pallidus (GP), a neuronal nucleus in the basal ganglia involved in the control of motor behavior. By using rat GP isolated nerve terminals (synaptosomes), we studied whether H3R activation modified the previously reported enhancing action of adenosine A2A receptor (A2AR) stimulation on depolarization-evoked [3H]-GABA release. At 3 and 10 nM, the A2AR agonist CGS-21680 enhanced [3H]-GABA release induced by high K+ (20 mM) and the effect of 3 nM CGS-21680 was prevented by the A2AR antagonist ZM-241385 (100 nM). The presence of presynaptic H3Rs was confirmed by the specific binding of N-α-[methyl-3H]-histamine to membranes from GP synaptosomes (maximum binding, Bmax, 1327 ± 79 fmol/mg protein; dissociation constant, Kd, 0.74 nM), which was inhibited by the H3R ligands immepip, clobenpropit, and A-331440 (inhibition constants, Ki, 0.28, 8.53, and 316 nM, respectively). Perfusion of synaptosomes with the H3R agonist immepip (100 nM) had no effect on K+-evoked [3H]-GABA release, but inhibited the stimulatory action of A2AR activation. In turn, the effect of immepip was blocked by the H3R antagonist clobenpropit, which had no significant effect of its own on K+-induced [3H]-GABA release. These data indicate that H3R activation selectively counteracts the facilitatory action of A2AR stimulation on GABA release from striato-pallidal projections. PMID:24884070

  10. Cannabinoid agonists stimulate [3H]GABA release in the globus pallidus of the rat when G(i) protein-receptor coupling is restricted: role of dopamine D2 receptors.

    PubMed

    Gonzalez, Brenda; Paz, Francisco; Florán, Leonor; Aceves, Jorge; Erlij, David; Florán, Benjamín

    2009-03-01

    The motor effects of cannabinoids in the globus pallidus appear to be caused by increases in interstitial GABA. To elucidate the mechanism of this response, we investigated the effect of the selective cannabinoid type 1 receptor (CB1) cannabinoid agonist arachidonyl-2-chloroethylamide (ACEA) on [(3)H]GABA release in slices of the rat globus pallidus. ACEA had two effects: concentrations between 10(-8) and 10(-6) M stimulated release, whereas higher concentrations (IC(50) approximately 10(-6) M) inhibited it. Another cannabinoid agonist, WIN-55,212-2, also had bimodal effects on release. Studies of cAMP production indicate that under conditions of low G(i/o), availability the coupling of CB1 receptors with G(i/o) proteins can be changed into CB1:G(s/olf) coupling; therefore, we determined the effects of conditions that limit G(i/o) availability on [(3)H]GABA release. Blockers of G(i/o) protein interactions, pertussis toxin and N-ethylmaleimide, transformed the inhibitory effects of ACEA on GABA release into stimulation. It also has been suggested that stimulation of D2 receptors can reduce G(i/o) availability. Blocking D2 receptors with sulpiride [(S)-5-aminosulfonyl-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2-methoxybenzamidersqb] or depleting dopamine with reserpine inhibited the ACEA-induced stimulation of release. Thus, the D2 dependence of stimulation is consistent with the proposal that D2 receptors reduce G(i/o) proteins available for binding to the CB1 receptor. In summary, CB1 receptor activation has dual effects on GABA release in the globus pallidus. Low concentrations stimulate release through a process that depends on activation of dopamine D2 receptors that may limit G(i/o) protein availability. Higher concentrations of cannabinoid inhibit GABA release through mechanisms that are independent of D2 receptor activation.

  11. Effects of Tityus serrulatus scorpion venom and its toxin TsTX-V on neurotransmitter uptake in vitro.

    PubMed

    Cecchini, Alessandra L; Vasconcelos, Flávio; Amara, Susan G; Giglio, José Roberto; Arantes, Eliane Candiani

    2006-12-01

    Scorpion neurotoxins targeting the Na(v) channel can be classified into two classes: alpha- and beta-neurotoxins and are reported as highly active in mammalian brain. In this work, we evaluate the effects of Tityus serrulatus venom (Ts venom) and its alpha-neurotoxin TsTX-V on gamma-aminobutyric acid (GABA), dopamine (DA) and glutamate (Glu) uptake in isolated rat brain synaptosomes. TsTX-V was isolated from Ts venom by ion exchange chromatography followed by reverse-phase (C18) high-performance liquid chromatography. Neither Ts venom nor TsTX-V was able to affect (3)H-Glu uptake. On the other hand, Ts venom (0.13 microg/mg) significantly inhibited both (3)H-GABA and (3)H-DA uptake ( approximately 50%). TsTX-V showed IC(50) values of 9.37 microM and 22.2 microM for the inhibition of (3)H-GABA and (3)H-DA uptake, respectively. These effects were abolished by pre-treatment with tetrodotoxin (TTX, 1 microM), indicating the involvement of voltage-gated Na(+) channels in this process. In the absence of Ca(2+), and at low Ts venom concentrations, the reduction of (3)H-GABA uptake was not as marked as in the presence of Ca(2+). TsTX-V did not reduce (3)H-GABA uptake in COS-7 cells expressing the GABA transporters GAT-1 and GAT-3, suggesting that this toxin indirectly reduces the transport. The reduced (3)H-GABA uptake by synaptosomes might be due to rapid cell depolarization as revealed by confocal microscopy of C6 glioma cells. Thus, TsTX-V causes a reduction of (3)H-GABA and (3)H-DA uptake in a Ca(2+)-dependent manner, not directly affecting GABA transporters, but, in consequence of depolarization, involving voltage-gated Na(+) channels.

  12. Growth cones isolated from developing rat forebrain: uptake and release of GABA and noradrenaline.

    PubMed

    Lockerbie, R O; Gordon-Weeks, P R; Pearce, B R

    1985-08-01

    A growth cone-enriched fraction isolated from neonatal rat forebrain was shown to accumulate gamma-amino [3H]butyric acid ([3H]-GABA) and [3H]noradrenaline ([3H]NA). Uptake of both neurotransmitters was sodium- and temperature-dependent and exhibited saturation kinetics with Km values of 17.7 microM and 4.5 microM respectively and Vmax values of 114 pmol/min/mg protein and 59 pmol/min/mg protein respectively. Electron microscopic autoradiography showed that about 50% of isolated growth cones can accumulate [3H]GABA. Inhibitor studies showed that beta-alanine was a relatively weak inhibitor of [3H]GABA uptake compared to nipecotic acid and diamino-butyric acid. Growth cone fractions preloaded with [3H]GABA and [3H]NA demonstrated a K+ (25 mM) -induced release of both neurotransmitters. Of the K+-stimulated release of [3H]GABA 50% was Ca2+-dependent, whereas the release of [3H]NA was entirely Ca2+-independent.

  13. Measuring the serotonin uptake site using (/sup 3/H)paroxetine--a new serotonin uptake inhibitor

    SciTech Connect

    Gleiter, C.H.; Nutt, D.J.

    1988-01-01

    Serotonin is an important neurotransmitter that may be involved in ethanol preference and dependence. It is possible to label the serotonin uptake site in brain using the tricyclic antidepressant imipramine, but this also binds to other sites. We have used the new high-affinity uptake blocker paroxetine to define binding to this site and report it to have advantages over imipramine as a ligand.

  14. Manganese accumulation in membrane fractions of primary astrocytes is associated with decreased γ-aminobutyric acid (GABA) uptake, and is exacerbated by oleic acid and palmitate.

    PubMed

    Fordahl, Steve C; Erikson, Keith M

    2014-05-01

    Manganese (Mn) exposure interferes with GABA uptake; however, the effects of Mn on GABA transport proteins (GATs) have not been identified. We sought to characterize how Mn impairs GAT function in primary rat astrocytes. Astrocytes exposed to Mn (500 μM) had significantly reduced (3)H-GABA uptake despite no change in membrane or cytosolic GAT3 protein levels. Co-treatment with 100 μM oleic or palmitic acids (both known to be elevated in Mn neurotoxicity), exacerbated the Mn-induced decline in (3)H-GABA uptake. Mn accumulation in the membrane fraction of astrocytes was enhanced with fatty acid administration, and was negatively correlated with (3)H-GABA uptake. Furthermore, control cells exposed to Mn only during the experimental uptake had significantly reduced (3)H-GABA uptake, and the addition of GABA (50 μM) blunted cytosolic Mn accumulation. These data indicate that reduced GAT function in astrocytes is influenced by Mn and fatty acids accumulating at or interacting with the plasma membrane.

  15. Distribution and ultrastructure of neurons in opossum piriform cortex displaying immunoreactivity to GABA and GAD and high-affinity tritiated GABA uptake

    SciTech Connect

    Haberly, L.B.; Hansen, D.J.; Feig, S.L.; Presto, S.

    1987-12-08

    GABAergic neurons have been identified in the piriform cortex of the opossum at light and electron microscopic levels by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase and by autoradiographic visualization of high-affinity /sup 3/H-GABA uptake. Four major neuron populations have been distinguished on the basis of soma size, shape, and segregation at specific depths and locations: large horizontal cells in layer Ia of the anterior piriform cortex, small globular cells with thin dendrites concentrated in layers Ib and II of the posterior piriform cortex, and multipolar and fusiform cells concentrated in the deep part of layer III in anterior and posterior parts of the piriform cortex and the subjacent endopiriform nucleus. All four populations were well visualized with both antisera, but the large layer Ia horizontal cells displayed only very light /sup 3/H-GABA uptake, thus suggesting a lack of local axon collaterals or lack of high-affinity GABA uptake sites. The large, ultrastructurally distinctive somata of layer Ia horizontal cells receive a very small number of symmetrical synapses; the thin, axonlike dendrites of small globular cells are exclusively postsynaptic and receive large numbers of both symmetrical and asymmetrical synapses, in contrast to somata which receive a small number of both types; and the deep multipolar and fusiform cells receive a highly variable number of symmetrical and asymmetrical synapses on somata and proximal dendrites. Labeled puncta of axon terminal dimensions were found in large numbers in the neuropil surrounding pyramidal cell somata in layer II and in the endopiriform nucleus. Moderately large numbers of labeled puncta were found in layer I at the depth of pyramidal cell apical dendrites with greater numbers in layer Ia at the depth of distal apical segments than in layer Ib.

  16. Effects of Tityus serrulatus scorpion venom and its toxin TsTX-V on neurotransmitter uptake in vitro

    SciTech Connect

    Cecchini, Alessandra L.; Vasconcelos, Flavio; Giglio, Jose Roberto; Arantes, Eliane Candiani . E-mail: ecabraga@fcfrp.usp.br

    2006-12-01

    Scorpion neurotoxins targeting the Na{sub v} channel can be classified into two classes: {alpha}- and {beta}-neurotoxins and are reported as highly active in mammalian brain. In this work, we evaluate the effects of Tityus serrulatus venom (Ts venom) and its {alpha}-neurotoxin TsTX-V on {gamma}-aminobutyric acid (GABA), dopamine (DA) and glutamate (Glu) uptake in isolated rat brain synaptosomes. TsTX-V was isolated from Ts venom by ion exchange chromatography followed by reverse-phase (C18) high-performance liquid chromatography. Neither Ts venom nor TsTX-V was able to affect {sup 3}H-Glu uptake. On the other hand, Ts venom (0.13 {mu}g/mg) significantly inhibited both {sup 3}H-GABA and {sup 3}H-DA uptake ({approx} 50%). TsTX-V showed IC{sub 5} values of 9.37 {mu}M and 22.2 {mu}M for the inhibition of {sup 3}H-GABA and {sup 3}H-DA uptake, respectively. These effects were abolished by pre-treatment with tetrodotoxin (TTX, 1 {mu}M), indicating the involvement of voltage-gated Na{sup +} channels in this process. In the absence of Ca{sup 2+}, and at low Ts venom concentrations, the reduction of {sup 3}H-GABA uptake was not as marked as in the presence of Ca{sup 2+}. TsTX-V did not reduce {sup 3}H-GABA uptake in COS-7 cells expressing the GABA transporters GAT-1 and GAT-3, suggesting that this toxin indirectly reduces the transport. The reduced {sup 3}H-GABA uptake by synaptosomes might be due to rapid cell depolarization as revealed by confocal microscopy of C6 glioma cells. Thus, TsTX-V causes a reduction of {sup 3}H-GABA and {sup 3}H-DA uptake in a Ca{sup 2+}-dependent manner, not directly affecting GABA transporters, but, in consequence of depolarization, involving voltage-gated Na{sup +} channels.

  17. Uptake and release of [3H]gamma-aminobutyric acid by embryonic spinal cord neurons in dissociated cell culture

    PubMed Central

    1979-01-01

    We have investigated the uptake and release of [3H]gamma-aminobutyric acid (GABA) by embryonic chick spinal cord cells maintained in culture. Cells dissociated from 4- or 7-d-old embryos were studied between 1 and 3 wk after plating. At 3 degrees C, [3H]GABA was accumulated by a high affinity (Km approximately equal to 4 microM) and a low affinity (Km approximately equal to 100 microM) mechanism. The high affinity transport was markedly inhibited in low Na+ media, by ouabain, at 0 degrees C, and by 2,4-diaminobutyric acid. Autoradiography, after incubation in 0.1 microM [3H]GABA, showed that approximately 50% (range = 30-70%) of the multipolar cells were labeled. These cells were neurons rather than glia; action potentials and/or synaptic potentials were recorded in cells subsequently found to be labeled. Non-neuronal, fibroblast-like cells and co-cultured myotubes were not labeled under the same conditions. The fact that not all of the neurons were labeled is consistent with the suggestion, based on studies of intact adult tissue, that high affinity transport of [3H]GABA may be unique to neurons that use GABA as a neurotransmitter. Our finding that none of fifteen physiologically identified cholinergic neurons, i.e., cells that innervated nearby myotubes, were heavily labeled after incubation in 0.1 microM [3H]GABA is significant in this regard. The newly taken up [3H]GABA was not metabolized in the short run. It was stored in a form that could be released when the neurons were depolarized in a high K+ (100 mM) medium. As expected for a neurotransmitter, the K+-evoked release was reversibly inhibited by reducing the extracellular Ca++/Mg++ ratio. PMID:457763

  18. Reduced number of caudate nucleus dopamine uptake sites in vascular dementia.

    PubMed

    Allard, P; Englund, E; Marcusson, J

    1999-01-01

    The dopamine (DA) uptake sites in the caudate nucleus were studied in patients with vascular dementia (VAD) and in a control group using the presynaptic DA uptake site marker [3H][2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane] as radioligand. There was a significant decrease in the number of DA uptake sites in the VAD group, while the binding affinity was unchanged. The present results indicate that in the patients investigated, the cerebrovascular disease process involves dopaminergic neuron terminals in the caudate nucleus. Our findings are discussed in relation to the reductions in number of DA uptake sites that have previously been revealed in Alzheimer's and Parkinson's diseases.

  19. [Methoxyflurane and ethanol do not inhibit the neuronal uptake of noradrenaline (uptake 1) at the desipramine binding site].

    PubMed

    Kress, H G; Schömig, E

    1990-07-01

    We recently demonstrated that the net accumulation of 3H-norepinephrine in the rat pheochromocytoma cell line PC12 was reduced by anesthetic concentrations of n-alkanols and the volatile anesthetics halothane, enflurane, isoflurane, and methoxyflurane. In PC12 cells, as in adrenergic neurons, norepinephrine is transported across the plasma membrane by a saturable, high-affinity, carrier-mediated mechanism (uptake1), which follows Michaelis-Menten kinetics, is energy- and sodium-dependent, and is inhibited by low concentrations of cocaine and the tricyclic antidepressant desipramine. Although uptake1 is the most important process for the removal of norepinephrine from the synaptic cleft, the net accumulation of norepinephrine within the neuron also depends on other factors including its vesicular uptake and storage within the granules, its metabolism by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT), and the efflux of its more lipophilic metabolites. In our previous report we could not exclude the contribution of any of these factors to the observed inhibitory effects of volatile substances. Therefore, the aim of the present study with ethanol and methoxyflurane was: (1) to elucidate further the exact mechanism responsible for the reduction of the norepinephrine accumulation; and (2) to investigate the anesthetics' interaction with the substrate recognition site, which is identical with the desipramine binding site on the norepinephrine carrier. METHODS. For 3H-norepinephrine uptake experiments, PC12 cells were cultured on dishes (60 mm, Nunc) coated with polyornithine. Reserpine (10 microM) was added to the culture 24 h before the experiment to deplete endogenous norepinephrine. The initial carrier-mediated transport rate (60 s) was measured as previously described. 3H-desipramine equilibrium binding was determined with isolated plasma membranes prepared from PC12 cells grown in suspension culture. The carrier-mediated uptake of 3H

  20. Autoradiographic localization of adenosine uptake sites in rat brain using (/sup 3/H)nitrobenzylthioinosine

    SciTech Connect

    Bisserbe, J.C.; Patel, J.; Marangos, P.J.

    1985-02-01

    The adenosine uptake site has been localized in rat brain by an in vitro light microscopic autoradiographic method, using (/sup 3/H)nitrobenzylthioinosine ((/sup 3/H)NBI) as the probe. The binding characteristics of (/sup 3/H)NBI on slide-mounted sections are comparable to those seen in studies performed on brain homogenates. A very high density of uptake sites occurs in the nucleus tractus solitarius, in the superficial layer of the superior colliculus, in several thalamic nuclei, and also in geniculate body nuclei. A high density of sites are also observed in the nucleus accumbens, the caudate putamen, the dorsal tegmentum area, the substantia nigra, and the central gray. The localization of the adenosine uptake site in brain may provide information on the functional activity of the site and suggests the involvement of the adenosine system in the central regulation of cardiovascular function.

  1. Dopamine uptake sites in the striatum are distributed differentially in striosome and matrix compartments

    SciTech Connect

    Graybiel, A.M.; Moratalla, R. )

    1989-11-01

    A major mechanism of neurotransmitter inactivation at catecholaminergic synapses in reuptake of released transmitter at high-affinity uptake sites on presynaptic terminals. The authors have analyzed the anatomical distribution of site-selective ligand binding for dopamine uptake sites in the striatum of rat, cat, and monkey. The authors report here that desipramine-sensitive ({sup 3}H)mazindol binding sites have highly heterogeneous distributions in the dorsal and the ventral striatum. In the caudate nucleus of cat and monkey, ({sup 3}H)mazindol binding observes striosomal ordering, being reduced in striosomes and heightened in the extrastriosomal matrix. Some local heterogeneity appears in the ventral caudoputamen of the rat. Different subdivisions of the nucleus accumbens also have different binding levels. These findings suggest that some functional effects of psychoactive drugs, such as cocaine, and that bind to the dopamine-uptake complex could be related to the distribution of these specific uptake sites. The findings also raise the possibility that these distributions could result in selective neuronal vulnerability to neurotoxins, such as 1-methyl-4-phenylpyridine (MPP{sup +}), that depend on the dopamine-uptake complex for entry into neurons.

  2. An overview of muscle glucose uptake during exercise. Sites of regulation.

    PubMed

    Wasserman, D H; Halseth, A E

    1998-01-01

    The uptake of blood glucose by skeletal muscle is a complex process. In order to be metabolized, glucose must travel the path from blood to interstitium to intracellular space and then be phosphorylated to glucose 6-phosphate (G6P). Movement of glucose from blood to interstitium is determined by skeletal muscle blood flow, capillary recruitment and the endothelial permeability to glucose. The influx of glucose from the interstitium to intracellular space is determined by the number of glucose transporters in the sarcolemma and the glucose gradient across the sarcolemma. The capacity to phosphorylate glucose is determined by the amount of skeletal muscle hexokinase II, hexokinase II compartmentalization within the cell, and the concentration of the hexokinase II inhibitor G6P. Any change in glucose uptake occurs due to an alteration in one or more of these steps. Based on the low calculated intracellular glucose levels and the higher affinity of glucose for phosphorylation relative to transport, glucose transport is generally considered rate-determining for basal muscle glucose uptake. Exercise increases both the movement of glucose from blood to sarcolemma and the permeability of the sarcolemma to glucose. Whether the ability to phosphorylate glucose is increased in the working muscle remains to be clearly shown. It is possible that the accelerated glucose delivery and transport rates during exercise bias regulation so that muscle glucose phosphorylation exerts more control on muscle glucose uptake. Conditions that alter glucose uptake during exercise, such as increased NEFA concentrations, decreased oxygen availability and adrenergic stimulation, must work by altering one or more of the three steps involved in glucose uptake. This review describes the regulation of glucose uptake during exercise at each of these sites under a number of conditions, as well as describing muscle glucose uptake in the post-exercise state.

  3. Autoradiographic localization of /sup 3/H-paroxetine-labeled serotonin uptake sites in rat brain

    SciTech Connect

    De Souza, E.B.; Kuyatt, B.L.

    1987-01-01

    Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H-paroxetine; 3H-paroxetine binding in slide-mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H-paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H-paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H-paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H-paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H-paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4-methylenedioxyamphetamine caused large decreases in 3H-paroxetine binding. The autoradiographic distribution of 3H-paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin.

  4. Native Plant Uptake Model for Radioactive Waste Disposal Areas at the Nevada Test Site

    SciTech Connect

    BROWN,THERESA J.; WIRTH,SHARON

    1999-09-01

    This report defines and defends the basic framework, methodology, and associated input parameters for modeling plant uptake of radionuclides for use in Performance Assessment (PA) activities of Radioactive Waste Management Sites (RWMS) at the Nevada Test Site (NTS). PAs are used to help determine whether waste disposal configurations meet applicable regulatory standards for the protection of human health, the environment, or both. Plants adapted to the arid climate of the NTS are able to rapidly capture infiltrating moisture. In addition to capturing soil moisture, plant roots absorb nutrients, minerals, and heavy metals, transporting them within the plant to the above-ground biomass. In this fashion, plant uptake affects the movement of radionuclides. The plant uptake model presented reflects rooting characteristics important to plant uptake, biomass turnover rates, and the ability of plants to uptake radionuclides from the soil. Parameters are provided for modeling plant uptake and estimating surface contaminant flux due to plant uptake under both current and potential future climate conditions with increased effective soil moisture. The term ''effective moisture'' is used throughout this report to indicate the soil moisture that is available to plants and is intended to be inclusive of all the variables that control soil moisture at a site (e.g., precipitation, temperature, soil texture, and soil chemistry). Effective moisture is a concept used to simplify a number of complex, interrelated soil processes for which there are too little data to model actual plant available moisture. The PA simulates both the flux of radionuclides across the land surface and the potential dose to humans from that flux. Surface flux is modeled here as the amount of soil contamination that is transferred from the soil by roots and incorporated into aboveground biomass. Movement of contaminants to the surface is the only transport mechanism evaluated with the model presented here

  5. Rates and tissue sites of non-insulin- and insulin-mediated glucose uptake in humans

    SciTech Connect

    Baron, A.D.; Brechtel, G.; Wallace, P.; Edelman, S.V.

    1988-12-01

    In vivo glucose uptake can occur via two mechanisms, namely, insulin-mediated glucose uptake (IMGU) and non-insulin-mediated glucose uptake (NIMGU). Although the principal tissue sites for IMGU are skeletal muscle, the tissue sites for NIMGU at a given serum glucose concentration are not known. To examine this issue, rates of whole body glucose uptake (Rd) were measured at basal and during glucose clamp studies performed at euglycemia (approximately 90 mg/dl) and hyperglycemia (approximately 220 mg/dl) in six lean healthy men. Studies were performed during hyperinsulinemia (approximately 70 microU/ml) and during somatostatin-induced insulinopenia to measure IMGU and NIMGU, respectively. During each study, leg glucose balance (arteriovenous catheter technique) was also measured. With this approach, rates of whole body skeletal muscle IMGU and NIMGU can be estimated, and the difference between overall Rd and skeletal muscle glucose uptake represents non-skeletal muscle Rd. The results indicate that approximately 20% of basal Rd is into skeletal muscle. During insulinopenia approximately 86% of body NIMGU occurs in non-skeletal muscle tissues at euglycemia. When hyperglycemia was created, whole body NIMGU increased from 128 +/- 6 to 213 +/- 18 mg/min (P less than 0.01); NIMGU into non-skeletal muscle tissues was 134 +/- 11 and 111 +/- 6 mg/min at hyperglycemia and euglycemia, respectively, P = NS. Therefore, virtually all the hyperglycemia induced increment in NIMGU occurred in skeletal muscle. During hyperinsulinemia, IMGU in skeletal muscle represented 75 and 95% of body Rd, at euglycemia and hyperglycemia, respectively.

  6. Identification of a lithium interaction site in the gamma-aminobutyric acid (GABA) transporter GAT-1.

    PubMed

    Zhou, Yonggang; Zomot, Elia; Kanner, Baruch I

    2006-08-01

    The sodium- and chloride-dependent electrogenic gamma-aminobutyric acid (GABA) transporter GAT-1, which transports two sodium ions together with GABA, is essential for synaptic transmission by this neurotransmitter. Although lithium by itself does not support GABA transport, it has been proposed that lithium can replace sodium at one of the binding sites but not at the other. To identify putative lithium selectivity determinants, we have mutated the five GAT-1 residues corresponding to those whose side chains participate in the sodium binding sites Na1 and Na2 of the bacterial leucine-transporting homologue LeuT(Aa). In GAT-1 and in most other neurotransmitter transporter family members, four of these residues are conserved, but aspartate 395 replaces the Na2 residue threonine 354. At varying extracellular sodium, lithium stimulated sodium-dependent transport currents as well as [3H]GABA uptake in wild type GAT-1. The extent of this stimulation was dependent on the GABA concentration. In mutants in which aspartate 395 was replaced by threonine or serine, the stimulation of transport by lithium was abolished. Moreover, these mutants were unable to mediate the lithium leak currents. This phenotype was not observed in mutants at the four other positions, although their transport properties were severely impacted. Thus at saturating GABA, the site corresponding to Na2 behaves as a low affinity sodium binding site where lithium can replace sodium. We propose that GABA participates in the other sodium binding site, just like leucine does in the Na1 site, and that at limiting GABA, this site determines the apparent sodium affinity of GABA transport.

  7. Uptake of nitroaromatic compounds in plants : Implications for risk assessment of ammunition sites.

    PubMed

    Schneider, K; Oltmanns, J; Radenberg, T; Schneider, T; Pauly-Mundegar, D

    1996-09-01

    The uptake of nitroaromatic compounds by plants from the soil was studied at an ammunition site. After the development of analytical methods for 2,4,6-trinitrotoluene, aminodinitrotoluenes and dinitrotoluenes in plant material, we could show that these substances accumulated in the roots of plants and are found to a lesser extent inleaves and stems. We observed only moderate differences between various plant species. It is likely that a metabolic transformation in plants leads to the formation of dinitrotoluenes which are considered to be potent carcinogens. Results from soils with a wide range of explosive concentrations show a good correlation between the plant and soil concentrations. The relative accumulation in plant material is higher at lower soil concentrations. At low soil concentrations of about 1 mg trinitrotoluene/kg soil, an accumulation factor of about 0.5 can be derived. These data are an important input for the risk assessment of ammunition sites.

  8. Differential visualization of dopamine and norepinephrine uptake sites in rat brain using (/sup 3/H)mazindol autoradiography

    SciTech Connect

    Javitch, J.A.; Strittmatter, S.M.; Snyder, S.H.

    1985-06-01

    Mazindol is a potent inhibitor of neuronal dopamine (DA) and norepinephrine (NE) uptake. DA and NE uptake sites in rat brain have been differentially visualized using (/sup 3/H)mazindol autoradiography. At appropriate concentrations, desipramine (DMI) selectively inhibits (/sup 3/H)mazindol binding to NE uptake sites without significantly affecting binding to DA uptake sites. The localization of DMI-insensitive specific (/sup 3/H) mazindol binding, reflecting DA uptake sites, is densest in the caudate-putamen, the nucleus accumbens, the olfactory tubercle, the subthalamic nucleus, the ventral tegmental area, the substantia nigra (SN) pars compacta, and the anterior olfactory nuclei. In contrast, the localization of DMI-sensitive specific (/sup 3/H)mazindol binding, representing NE uptake sites, is densest in the locus coeruleus, the nucleus of the solitary tract, the bed nucleus of the stria terminalis, the paraventricular and periventricular nuclei of the hypothalamus, and the anteroventral thalamus. The distribution of DMI-insensitive specific (/sup 3/H)mazindol binding closely parallels that of dopaminergic terminal and somatodendritic regions, while the distribution of DMI-sensitive specific (/sup 3/H)mazindol binding correlates well with the regional localization of noradrenergic terminals and cell bodies. Injection of 6-hydroxydopamine, ibotenic acid, or colchicine into the SN decreases (/sup 3/H)mazindol binding to DA uptake sites in the ipsilateral caudate-putamen by 85%. In contrast, ibotenic acid lesions of the caudate-putamen do not reduce (/sup 3/H)mazindol binding to either the ipsilateral or contralateral caudate-putamen.

  9. Effects of repeated oral doses of dexnorfenfluramine on 5-HT levels and 5-HT uptake sites in rat brain.

    PubMed

    Gobbi, M; Bergami, A; Caltavuturo, C; Valle, F D; Mennini, T; Caccia, S

    1996-11-15

    The effects of oral dexnorfenfluramine (DNF; 1-4 mg/kg, twice daily for 4 days), the active metabolite of dexfenfluramine, were examined on rat regional brain indole contents and [3H]citalopram binding. Two hours after the last dose, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were dose-dependently lowered at doses above 1.5 mg/kg, with slight regional differences. Cortical 5-HT uptake sites were reduced only at the highest dose. Above 2 mg/kg DNF also caused a more lasting reduction (4 weeks) of regional indoles and cortical 5-HT uptake sites. At this longer time while the decrease in hippocampal 5-HT levels and cortical 5-HT uptake sites remained essentially constant, cortical and striatal 5-HT levels were lowered less than at 2 h, suggesting a return toward control values.

  10. Water uptake by two river red gum ( Eucalyptus camaldulensis) clones in a discharge site plantation in the Western Australian wheatbelt

    NASA Astrophysics Data System (ADS)

    Marshall, John K.; Morgan, Anne L.; Akilan, Kandia; Farrell, Richard C. C.; Bell, David T.

    1997-12-01

    The heat-pulse technique was used to estimate year-long water uptake in a discharge zone plantation of 9-year-old clonal Eucalyptus camaldulensis Dehnh. near Wubin, Western Australia. Water uptake matched rainfall closely during weter months but exceeded rainfall as the dry season progressed. Average annual water uptake (1148 mm) exceeded rainfall (432 mm) by about 2.7 fold and approached 56% of pan evaporation for the area. The data suggest that at least 37% (i.e. ( {1}/{2.7}) × 100 ) of the lower catchment discharge zone should be planted to prevent the rise of groundwater. Water uptake varied with soil environment, season and genotype. Upslope trees used more water than did downslope trees. Water uptake was higher in E. camaldulensis clone M80 than in clone M66 until late spring. The difference reversed as summer progressed. Both clones, however, have the potential to dry out the landscape when potential evapotranspiration exceeds rainfall. This variation in water uptake within the species indicates the potential for manipulating plantation uptake by matching tree characteristics to site characteristics. Controlled experiments on the heat-pulse technique indicated accuracy errors of approximately 10%. This, combined with the ability to obtain long-term, continuous data and the superior logistics of use of the heat-pulse technique, suggests that results obtained by it would be much more reliable than those achieved by the ventilated chamber technique.

  11. Sites of calcium uptake of fish otoliths correspond with macular regions rich of carbonic anhydrase

    NASA Astrophysics Data System (ADS)

    Beier, M.; Anken, R.; Hilbig, R.

    2006-01-01

    Based on pharmacological data, it has been suggested that the enzyme carbonic anhydrase (CAH) plays a prominent role in the mineralization of fish otoliths. To directly test this proposal, the topographical distribution of CAH was histochemically analyzed in the utricular and saccular maculae of larval cichlid fish Oreochromis mossambicus. Further investigations were focussed on the sites of otolithic calcium uptake using the fluorescent calcium tracer alizarin-complexone (AC). Both in the utricle and the saccule, CAH-reactivity was prominent in regions on both sides of the sensory macula (centrifugal (cf) and centripetal (cp) areas), which reportedly contain ionocytes, specialized cells regulating the ionic composition of the endolymph. (The terms centrifugal and centripetal were chosen instead of lateral and medial, because the saccule is positioned perpendicular to the utricle; “lateral” and “medial” thus do not allow an unambiguous allocation of the respective regions.) In the saccule, the size of cf and cp did not differ from each other, whereas, in the utricle, cp was considerably larger as compared to cf (CAH-reactivity per μm2 was nearly identical in both areas of both endorgans). AC-incubation resulted in a fluorescent band on the proximal surface of the otoliths (this surface lies next to the sensory epithelium). In saccular otoliths (sagittae), the area of the band did not differ between centrifugal and centripetal otolith regions, whereas in the utricular otoliths (lapilli), the area of the centripetal AC-band was larger in size as compared to the centrifugal one (AC-fluorescence per μm2 did not differ between the areas analyzed in both types of otoliths). These results strongly suggest that calcium/carbonate uptake of otoliths takes place especially in those regions of their proximal face which are located adjacent to CAH-rich areas of the macular epithelium. It is thus concluded that CAH is directly involved in otolith calcification. The

  12. Effects of high-dose fenfluramine treatment on monoamine uptake sites in rat brain: Assessment using quantitative autoradiography

    SciTech Connect

    Appel, N.M.; Mitchell, W.M.; Contrera, J.F.; De Souza, E.B. )

    1990-01-01

    Fenfluramine is an amphetamine derivative that in humans is used primarily as an anorectic agent in the treatment of obesity. In rats, subchronic high-dose d,l-fenfluramine treatment (24 mg/kg subcutaneously, twice daily for 4 days) causes long-lasting decreases in brain serotonin (5HT), its metabolite 5-hydroxyindoleacetic acid, and high-affinity 5HT uptake sites. Moreover, this high-dose treatment regimen causes both selective long-lasting decreases in fine-caliber 5HT-immunoreactive axons and appearance of other 5HT-immunoreactive axons with morphology characteristic of degenerating axons. Determination of the potential neurotoxic effects of fenfluramine treatment using immunohistochemistry is limited from the perspectives that staining is difficult to quantify and that it relies on presence of the antigen (in this case 5HT), and the 5HT-depleting effects of fenfluramine are well known. In the present study, we used quantitative in vitro autoradiography to assess, in detail, the density and regional distribution of (3H)paroxetine-labeled 5HT and (3H)mazindol-labeled catecholamine uptake sites in response to the high-dose fenfluramine treatment described above. Because monoamine uptake sites are concentrated on monoamine-containing nerve terminals, decreases in uptake site density would provide a quantitative assessment of potential neurotoxicity resulting from this fenfluramine treatment regimen. Marked decreases in densities of (3H)paroxetine-labeled 5HT uptake sites occurred in brain regions in which fenfluramine treatment decreased the density of 5HT-like immunostaining when compared to saline-treated control rats. These included cerebral cortex, caudate putamen, hippocampus, thalamus, and medial hypothalamus.

  13. Soil contamination and plant uptake of heavy metals at polluted sites in China.

    PubMed

    Wang, Qing-Ren; Cui, Yan-Shan; Liu, Xiu-Mei; Dong, Yi-Ting; Christie, Peter

    2003-05-01

    We investigated heavy metal contamination in soils and plants at polluted sites in China including some with heavy industries, metal mining, smelting and untreated wastewater irrigation areas. We report our main findings in this paper. The concentrations of heavy metals, including Cd and Zn, in the soils at the investigated sites were above the background levels, and generally exceeded the Government guidelines for metals in soil. The concentrations of metals in plants served to indicate the metal contamination status of the site, and also revealed the abilities of various plant species to take up and accumulate the metals from the soil. Substantial differences in the accumulation of heavy metals were observed among the plant species investigated. Polygonum hydropiper growing on contaminated soils in a sewage pond had accumulated 1061 mg kg(-1) of Zn in its shoots. Rumex acetosa L. growing near a smelter had accumulated more than 900 mg kg(-1) of Zn both in its shoots and roots. Therefore these species have potential for phytoremediation of metal-contaminated sites. Our results indicate the need to elucidate the dynamics of soil metal contamination of plants and the onward movement of metal contaminants into the food chain. Also our results indicate that the consumption of rice grown in paddy soils contaminated with Cd, Cr or Zn may pose a serious risk to human health, because from 24 to 22% of the total metal content in the rice biomass was concentrated in the rice grain. Platanus acerifolia growing on heavily contaminated soil accumulated only very low levels of heavy metals, and this mechanism for excluding metal uptake may have value in crop improvement. Sources of metal entering the environmental matrices studied included untreated wastewater, tailings or slurries and dust depositions from metal ore mining, and sewage sludge. Pb, Zn or Cd concentrations declined with the distance from metal smelter in accordance with a good exponential correlation (R2

  14. Similarity of nutrient uptake and root dimensions of Engelmann spruce and subalpine fir at two contrasting sites in Colorado

    SciTech Connect

    Yanai, R; McFarlane, K; Lucash, M; Kulpa, S; Wood, D

    2009-10-09

    Nutrient uptake capacity is an important parameter in modeling nutrient uptake by plants. Researchers commonly assume that uptake capacity measured for a species can be used across sites. We tested this assumption by measuring the nutrient uptake capacity of intact roots of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) at Loch Vale Watershed and Fraser Experimental Forest in the Rocky Mountains of central Colorado. Roots still attached to the tree were exposed to one of three concentrations of nutrient solutions for time periods ranging from 1 to 96 hours, and solutions were analyzed for ammonium, nitrate, calcium, magnesium, and potassium. Surprisingly, the two species were indistinguishable in nutrient uptake within site for all nutrients (P > 0.25), but uptake rates differed by site. In general, nutrient uptake was higher at Fraser (P = 0.01, 0.15, 0.03, 0.18 for NH{sub 4}{sup +}, NO{sub 3}{sup -}, Ca{sup 2+}, and K{sup +}, respectively), which is west of the Continental Divide and has lower atmospheric deposition of N than Loch Vale. Mean uptake rates by site for ambient solution concentrations were 0.12 {micro}mol NH{sub 4}{sup +} g{sub fwt}{sup -1} h{sup -1}, 0.02 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1}, 0.21 {micro}mol Ca{sup 2+} g{sub fwt}{sup -1} h{sup -1}, and 0.01 {micro}mol Mg{sup 2+} g{sub fwt}{sup -1} h{sup -1} at Loch Vale, and 0.21 {micro}mol NH{sub 4}{sup +} f{sub fwt}{sup -1}h{sup -1}, 0.04 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1} h{sup -1}, 0.51 {micro}mol Ca{sup 2+}g{sub fwt}{sup -1}h{sup -1}, and 0.07 {micro}mol Mg{sup 2+} f{sub fwt}{sup -1}h{sup -1} at Fraser. The importance of site conditions in determining uptake capacity should not be overlooked when parameterizing nutrient uptake models. We also characterized the root morphology of these two species and compared them to other tree species we have measured at various sites in the northeastern USA. Engelman spruce and subalpine fir

  15. In vivo labeling of 5-hydroxytryptamine uptake sites in mouse brain with ( sup 3 H)-6-nitroquipazine

    SciTech Connect

    Hashimoto, K.; Goromaru, T. )

    1990-10-01

    6-Nitroquipazine (DU 24565; 6-nitro 2-piperazinylquinoline) is a very potent 5-hydroxytryptamine (5-HT; serotonin) uptake inhibitor. It has been demonstrated very recently that (3H)-6-nitroquipazine is a suitable radioligand for studying 5-HT uptake sites. The present study evaluates (3H)6-nitroquipazine as a radioligand for in vivo labeling of 5-HT uptake sites in mouse brain. Very high uptake of radioactivity in the brain after i.v. administration of (3H)-6-nitroquipazine was shown. Regional distribution of the radioactivity in mouse brain 3 hr after injection of (3H)-6-nitroquipazine was in the order (highest to lowest) hypothalamus greater than midbrain greater than striatum greater than hippocampus greater than cerebral cortex greater than medulla oblongata greater than cerebellum. The regional distribution of in vivo (3H)-6-nitroquipazine binding in mouse brain was highly correlated with that in rat brain obtained from previous in vitro binding studies. Coadministration of carrier 6-nitroquipazine (5 mg/kg) significantly decreased the radioactivity in the hypothalamus, whereas that in the cerebellum and cerebral cortex was increased. Because the cerebellum has very low density of (3H)-6-nitroquipazine binding sites, the radioactivity in the cerebellum could, therefore, reflect the amount on nonspecific binding and free ligand. Kinetic studies showed highest in vivo specific binding 1 hr after injection of (3H)-6-nitroquipazine and slow clearance of specific binding. Specific binding in the hypothalamus was inhibited in a stereoselective manner by the stereoisomers of norzimelidine. Furthermore, specific binding in the hypothalamus was reduced by several 5-HT uptake inhibitors, in a dose-dependent manner.

  16. Exemplifying whole-plant ozone uptake in adult forest trees of contrasting species and site conditions.

    PubMed

    Nunn, Angela J; Wieser, Gerhard; Metzger, Ursula; Löw, Markus; Wipfler, Philip; Häberle, Karl-Heinz; Matyssek, Rainer

    2007-04-01

    Whole-tree O3 uptake was exemplified for Picea abies, Fagus sylvatica and Larix decidua in stands at high and low altitude and contrasting water availability through sap flow measurement in tree trunks, intrinsically accounting for drought and boundary layer effects on O3 flux. O3 uptake of evergreen spruce per unit foliage area was enhanced by 100% at high relative to low elevation, whereas deciduous beech and larch showed similar uptake regardless of altitude. The responsiveness of the canopy conductance to water vapor and, as a consequence, O3 uptake to soil moisture and air humidity did not differ between species. Unifying findings at the whole-tree level will promote cause-effect based O3 risk assessment and modeling. PMID:16996178

  17. Exemplifying whole-plant ozone uptake in adult forest trees of contrasting species and site conditions.

    PubMed

    Nunn, Angela J; Wieser, Gerhard; Metzger, Ursula; Löw, Markus; Wipfler, Philip; Häberle, Karl-Heinz; Matyssek, Rainer

    2007-04-01

    Whole-tree O3 uptake was exemplified for Picea abies, Fagus sylvatica and Larix decidua in stands at high and low altitude and contrasting water availability through sap flow measurement in tree trunks, intrinsically accounting for drought and boundary layer effects on O3 flux. O3 uptake of evergreen spruce per unit foliage area was enhanced by 100% at high relative to low elevation, whereas deciduous beech and larch showed similar uptake regardless of altitude. The responsiveness of the canopy conductance to water vapor and, as a consequence, O3 uptake to soil moisture and air humidity did not differ between species. Unifying findings at the whole-tree level will promote cause-effect based O3 risk assessment and modeling.

  18. High and Reversible Ammonia Uptake in Mesoporous Azolate Metal-Organic Frameworks with Open Mn, Co, and Ni Sites.

    PubMed

    Rieth, Adam J; Tulchinsky, Yuri; Dincă, Mircea

    2016-08-01

    A series of new mesoporous metal-organic frameworks (MOFs) made from extended bisbenzenetriazolate linkers exhibit coordinatively unsaturated metal sites that are responsible for high and reversible uptake of ammonia. Isostructural Mn, Co, and Ni materials adsorb 15.47, 12.00, and 12.02 mmol of NH3/g, respectively, at STP. Importantly, these near-record capacities are reversible for at least three cycles. These results demonstrate that azolate MOFs are sufficiently thermally and chemically stable to find uses in recyclable sorption, storage, and potentially separation of chemically challenging and/or corrosive gases, especially when designed to exhibit a high density of open metal sites.

  19. Different components of /sup 3/H-imipramine binding in rat brain membranes: relation to serotonin uptake sites

    SciTech Connect

    Gobbi, M.; Taddei, C.; Mennini, T.

    1988-01-01

    In the present paper, the authors confirm and extend previous studies showing heterogeneous /sup 3/H-imipramine (/sup 3/H-IMI) binding sites. Inhibition curves of various drugs (serotonin, imipramine, desmethyl-imipramine, d-fenfluramine, d-norfenfluramine and indalpine, a potent serotonin uptake inhibitor) obtained using 2 nM /sup 3/H-IMI and in presence of 120 mM NaCl, confirmed the presence of at least three /sup 3/H-IMI binding sites: two of these were serotonin-insensitive while the third one was selectively inhibited by serotonin and indalpine with nanomolar affinities. Moreover this last component was found to be selectively modulated by chronic imipramine treatment thus suggesting a close relation to serontonin uptake mechanism. These data indicate that the use of a more selective inhibitors of the serotonin-sensitive component (like indalpine or serotonin itself) to define non specific /sup 3/H-IMI, may be of help in understanding its relation with serotonin uptake system. 22 references, 2 figures, 2 tables.

  20. Knowledge, attitude, and uptake related to human papillomavirus vaccination among young women in Germany recruited via a social media site

    PubMed Central

    Remschmidt, Cornelius; Walter, Dietmar; Schmich, Patrick; Wetzstein, Matthias; Deleré, Yvonne; Wichmann, Ole

    2014-01-01

    Background: Many industrialized countries have introduced human papillomavirus (HPV) vaccination of young women, but vaccine uptake often remains suboptimal. This study aimed to investigate whether a social media site like Facebook is an appropriate tool to assess knowledge, attitude and uptake related to HPV vaccination in young women in Germany. Methods: Between December 2012 and January 2013 two different targeting strategies were implemented on Facebook, providing a link to an online questionnaire. Advertisements were displayed to female Facebook users aged 18–25 years living in Germany. During the simple targeting strategy, advertisements comprised health-related images along with various short titles and text messages. During the focused strategy, advertisements were targeted to users who in addition had certain fashion brands or pop stars listed on their profiles. The targeting strategies were compared with respect to participant characteristics. Univariate and multivariate analyses were used to identify factors associated with HPV vaccine uptake. Results: A total of 1161 women participated. The two targeting strategies resulted in significant differences regarding educational status and migrant background. Overall, awareness of HPV was high, but only 53% received at least one vaccine dose. In multivariate analysis, HPV vaccine uptake was independently associated with a physician's recommendation and trust in vaccine effectiveness. Concerns of adverse effects were negatively associated with vaccine uptake. Discussion: Social network recruitment permits fast and convenient access to young people. Sample characteristics can be manipulated by adjusting targeting strategies. There is further need for promoting knowledge of HPV vaccination among young women. Physicians have a major role in the vaccination decision-making process of young women. PMID:25483492

  1. Root water uptake model based on water potential gradient with water redistribution via roots: application to coniferous forest site

    NASA Astrophysics Data System (ADS)

    Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav

    2013-04-01

    A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction

  2. Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

    PubMed

    Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

    2016-07-01

    The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area. PMID:27149147

  3. Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

    PubMed

    Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

    2016-07-01

    The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area.

  4. Cellular sites of estrogen and antiestrogen uptake, retention and action: comparative autoradiographic studies in the immature rat uterus

    SciTech Connect

    Ennis, B.W.

    1987-01-01

    This purpose of this study is to clarify the mechanism of action of antiestrogens: agents used for treating breast cancer and as probes for studying the mechanisms of action of estrogen. Nuclear uptake and retention of estrogen and antiestrogen were determined in the different cell types of the immature rat uterus, by quantitative autoradiography, after an injection of tritiated hydroxytamoxifen ((/sup 3/H)TAM(OH)) or tritiated estradiol ((/sup 3/H)E/sub 2/). The effect of TAM(OH) and E/sub 2/ on progesterone receptor content was assessed in the different cell types by determining nuclear uptake of the synthetic progestin (/sup 3/H)Org 2058. The results indicate that antiestrogen and estrogen localize to nuclei of the same uterine cell types, but that this nuclear uptake differs among the uterine tissue compartments, that antiestrogen is taken up considerably slower and retained longer than estrogen and that antiestrogen and estrogen differentially affect progesterone receptor content in the different cell types. The results further suggest that antiestrogen-specific binding sites exist in the cytoplasm of uterine luminal epithelium.

  5. Site-Specific Radioiodination of HER2-Targeting Affibody Molecules using 4-Iodophenethylmaleimide Decreases Renal Uptake of Radioactivity

    PubMed Central

    Strand, Joanna; Nordeman, Patrik; Honarvar, Hadis; Altai, Mohamed; Orlova, Anna; Larhed, Mats; Tolmachev, Vladimir

    2015-01-01

    Affibody molecules are small scaffold-based affinity proteins with promising properties as probes for radionuclide-based molecular imaging. However, a high reabsorption of radiolabeled Affibody molecules in kidneys is an issue. We have shown that the use of 125I-3-iodo-((4-hydroxyphenyl)ethyl)maleimide (IHPEM) for site-specific labeling of cysteine-containing Affibody molecules provides high tumor uptake but low radioactivity retention in kidneys. We hypothesized that the use of 4-iodophenethylmaleimide (IPEM) would further reduce renal retention of radioactivity because of higher lipophilicity of radiometabolites. An anti-human epidermal growth factor receptor type 2 (HER2) Affibody molecule (ZHER2:2395) was labeled using 125I-IPEM with an overall yield of 45±3 %. 125I-IPEM-ZHER2:2395 bound specifically to HER2-expressing human ovarian carcinoma cells (SKOV-3 cell line). In NMRI mice, the renal uptake of 125I-IPEM-ZHER2:2395 (24±2 and 5.7±0.3 % IA g−1at 1 and 4 h after injection, respectively) was significantly lower than uptake of 125I-IHPEM-ZHER2:2395 (50±8 and 12±2 % IA g−1at 1 and 4 h after injection, respectively). In conclusion, the use of a more lipophilic linker for the radioiodination of Affibody molecules reduces renal radioactivity. PMID:25969816

  6. Selective labeling of serotonin uptake sites in rat brain by (/sup 3/H)citalopram contrasted to labeling of multiple sites by (/sup 3/H)imipramine

    SciTech Connect

    D'Amato, R.J.; Largent, B.L.; Snowman, A.M.; Snyder, S.H.

    1987-07-01

    Citalopram is a potent and selective inhibitor of neuronal serotonin uptake. In rat brain membranes (/sup 3/H)citalopram demonstrates saturable and reversible binding with a KD of 0.8 nM and a maximal number of binding sites (Bmax) of 570 fmol/mg of protein. The drug specificity for (/sup 3/H)citalopram binding and synaptosomal serotonin uptake are closely correlated. Inhibition of (/sup 3/H)citalopram binding by both serotonin and imipramine is consistent with a competitive interaction in both equilibrium and kinetic analyses. The autoradiographic pattern of (/sup 3/H)citalopram binding sites closely resembles the distribution of serotonin. By contrast, detailed equilibrium-saturation analysis of (/sup 3/H)imipramine binding reveals two binding components, i.e., high affinity (KD = 9 nM, Bmax = 420 fmol/mg of protein) and low affinity (KD = 553 nM, Bmax = 8560 fmol/mg of protein) sites. Specific (/sup 3/H)imipramine binding, defined as the binding inhibited by 100 microM desipramine, is displaced only partially by serotonin. Various studies reveal that the serotonin-sensitive portion of binding corresponds to the high affinity sites of (/sup 3/H)imipramine binding whereas the serotonin-insensitive binding corresponds to the low affinity sites. Lesioning of serotonin neurons with p-chloroamphetamine causes a large decrease in (/sup 3/H)citalopram and serotonin-sensitive (/sup 3/H)imipramine binding with only a small effect on serotonin-insensitive (/sup 3/H)imipramine binding. The dissociation rate of (/sup 3/H)imipramine or (/sup 3/H)citalopram is not altered by citalopram, imipramine or serotonin up to concentrations of 10 microM. The regional distribution of serotonin sensitive (/sup 3/H)imipramine high affinity binding sites closely resembles that of (/sup 3/H)citalopram binding.

  7. Uptake of gamma-aminobutyric acid and L-glutamic acid by synaptosomes from postmortem human cerebral cortex: multiple sites, sodium dependence and effect of tissue preparation.

    PubMed

    Dodd, P R; Watson, W E; Morrison, M M; Johnston, G A; Bird, E D; Cowburn, R F; Hardy, J A

    1989-06-26

    The uptake of gamma-aminobutyric acid (GABA) and L-glutamic acid by synaptosomes prepared from frozen postmortem human brain was shown to be effected via distinct high and low affinity sites. At approximately 17 h postmortem delay, the kinetic parameters for GABA uptake were: high affinity site, Km 7.1 +/- 2.5 microM, Vmax 18.7 +/- 4.8 nmol.min-1 per 100 mg protein; low affinity site, Km 2 +/- 1 mM, Vmax 425 +/- 250 nmol.min-1 per 100 mg protein (means +/- S.E.M., n = 13). Kinetic parameters for L-glutamate uptake were: high affinity site, Km 7.5 +/- 1.0 microM, Vmax 85 +/- 8 nmol.min-1 per 100 mg protein; low affinity site, Km 1.8 +/- 1.2 mM. Vmax 780 +/- 175 nmol.min-1 per 100 mg protein (n = 11). A detailed kinetic analysis of high affinity GABA uptake was performed over a range of sodium ion concentrations. The results were consistent with a coupling ratio of one Na+ ion to one GABA molecule; a similar result was found with rat brain synaptosomes. However, rat and human synaptosomes differed in the degree to which the substrate affinity of the high affinity GABA uptake site varied with decreasing Na+ ion concentration. High affinity GABA uptake was markedly affected by the method used to freeze and divide the tissue, but did not vary greatly in different cortical regions. There was some decline of high affinity GABA uptake activity with postmortem delay, apparently due to a loss of sites rather than a change in site affinity.

  8. A comparison of 90Sr and 137Cs uptake in plants via three pathways at two Chernobyl-contaminated sites.

    PubMed

    Malek, M A; Hinton, T G; Webb, S B

    2002-01-01

    Foliar absorption of resuspended 90Sr, root uptake and contamination adhering to leaf surfaces (i.e. soil loading) were compared at two Chernobyl-contaminated sites, Chistogalovka and Polesskoye. Although foliar absorption of resuspended 90Sr was quantifiable, its contribution amounted to less than 10% of the plants' total, above-ground contamination. Root uptake was 200 times greater than foliar absorption at the near-field site of Chistogalovka and eight times greater at Polesskoye, where the fallout consisted of the more soluble condensation-type, rather than fuel particles. Strontium's bioavailability exceeded that of 137Cs (analyzed in the same plants) by orders of magnitude when compared using concentration ratios. Simplistic, cumulative effective dose calculations for humans ingesting 90Sr- and 137Cs-contaminated plants revealed that the dose at Chistogalovka was greater from 90Sr (185 mSv vs. 3 mSv from 137Cs), while at Polesskoye the dose from 137Cs (66 mSv) was 30 times greater than from 90Sr (2 mSv). PMID:11814162

  9. Adenosine A2A receptor stimulation decreases GAT-1-mediated GABA uptake in the globus pallidus of the rat.

    PubMed

    Gonzalez, Brenda; Paz, Francisco; Florán, Leonor; Aceves, Jorge; Erlij, David; Florán, Benjamín

    2006-07-01

    We examined modulation of [(3)H]GABA uptake in slices of the rat globus pallidus because stimulation of adenosine A(2A) receptors increases extracellular GABA in this structure. Pharmacological analysis showed that GAT-1 is the main transporter present in these slices. Both adenosine and the A(2A) agonist CGS 21680 reduced GABA uptake. Antagonist ZM 241385 prevented these effects. Agents that increase protein kinase A activity like forskolin and 8-bromo-cAMP also inhibited GABA uptake. The inhibition of uptake produced by these substances and by CGS 21680 was prevented by the protein kinase A blocker H-89. The protein phosphatase blocker okadaic acid reduced uptake; this effect and the response to CGS 21680 were not additive. The effective concentrations of adenosine (EC(50)=15.2microM) are within the range measured in the interstitial fluid under some physiological conditions. Thus, inhibition of uptake may be important in increasing interstitial GABA during endogenous adenosine release.

  10. The cell pole: the site of cross talk between the DNA uptake and genetic recombination machinery.

    PubMed

    Kidane, Dawit; Ayora, Silvia; Sweasy, Joann B; Graumann, Peter L; Alonso, Juan C

    2012-01-01

    Natural transformation is a programmed mechanism characterized by binding of free double-stranded (ds) DNA from the environment to the cell pole in rod-shaped bacteria. In Bacillus subtilis some competence proteins, which process the dsDNA and translocate single-stranded (ss) DNA into the cytosol, recruit a set of recombination proteins mainly to one of the cell poles. A subset of single-stranded binding proteins, working as "guardians", protects ssDNA from degradation and limit the RecA recombinase loading. Then, the "mediators" overcome the inhibitory role of guardians, and recruit RecA onto ssDNA. A RecA·ssDNA filament searches for homology on the chromosome and, in a process that is controlled by "modulators", catalyzes strand invasion with the generation of a displacement loop (D-loop). A D-loop resolvase or "resolver" cleaves this intermediate, limited DNA replication restores missing information and a DNA ligase seals the DNA ends. However, if any step fails, the "rescuers" will repair the broken end to rescue chromosomal transformation. If the ssDNA does not share homology with resident DNA, but it contains information for autonomous replication, guardian and mediator proteins catalyze plasmid establishment after inhibition of RecA. DNA replication and ligation reconstitute the molecule (plasmid transformation). In this review, the interacting network that leads to a cross talk between proteins of the uptake and genetic recombination machinery will be placed into prospective.

  11. Beta-test Results for an HPV Information Web site: GoHealthyGirls.org – Increasing HPV Vaccine Uptake in the United States

    PubMed Central

    Nodulman, Jessica A.; Kong, Alberta S.; Wheeler, Cosette M.; Buller, David B.; Woodall, W. Gill

    2014-01-01

    A web site, GoHealthyGirls, was developed to educate and inform parents and their adolescent daughters about human papillomavirus (HPV) and HPV vaccines. This article provides an overview of web site development and content followed by the results of a beta-test of the web site. 63 New Mexican parents of adolescent girls tested the site. Results indicated that GoHealthyGirls was a functioning and appealing web site. During this brief educational intervention, findings suggest that the web site has the potential to increase HPV vaccine uptake. This research supports the Internet as a valuable channel to disseminate health education and information to diverse populations. PMID:25221442

  12. The cell pole: The site of cross talk between the DNA uptake and genetic recombination machinery

    PubMed Central

    Kidane, Dawit; Ayora, Silvia; Sweasy, Joann; Graumann, Peter L.; Alonso, Juan C.

    2012-01-01

    Natural transformation is a programmed mechanism characterized by binding of free double-stranded (ds) DNA from the environment to the cell pole in rod-shaped bacteria. In Bacillus subtilis some competence proteins, which process the dsDNA and translocate single-stranded (ss) DNA into the cytosol, recruit a set of recombination proteins mainly to one of the cell poles. A subset of single-stranded binding proteins, working as “guardians”, protect ssDNA from degradation and limit the RecA recombinase loading. Then, the “mediators” overcome the inhibitory role of guardians, and recruit RecA onto ssDNA. A RecA·ssDNA filament searches for homology on the chromosome and, in a process that is controlled by “modulators”, catalyzes strand invasion with the generation of a displacement loop (D-loop). A D-loop resolvase or “resolver” cleaves this intermediate, limited DNA replication restores missing information and a DNA ligase seals the DNA ends. However, if any step fails, the “rescuers” will repair the broken end to rescue chromosomal transformation. If the ssDNA does not share homology with resident DNA, but it contains information for autonomous replication, guardian and mediator proteins catalyze plasmid establishment after inhibition of RecA. DNA replication and ligation reconstitute the molecule (plasmid transformation). In this review, the interacting network that leads to a cross talk between proteins of the uptake and genetic recombination machinery will be placed into prospective. PMID:23046409

  13. Uptake of Human Papillomavirus Vaccine Among Adolescent Males and Females: Immunization Information System Sentinel Sites, 2009–2012

    PubMed Central

    Cullen, Karen A.; Stokley, Shannon; Markowitz, Lauri E.

    2015-01-01

    Objective The Advisory Committee on Immunization Practices (ACIP) has recommended routine human papillomavirus (HPV) vaccination at age 11 or 12 years for girls since 2006 and for boys since 2011. We sought to describe adolescent HPV vaccination coverage, doses administered from 2009 to 2012, and age at first vaccination by sex. Methods Aggregate data were analyzed from 8 Immunization Information System sentinel sites on HPV vaccinations in children and adolescents aged 11 to 12 years, 13 to 15 years, and 16 to 18 years. Vaccination coverage by age group was reported for 2009 to 2012, and weekly doses administered were determined. Age at first HPV vaccination was calculated for girls in 2007 and 2011 and for boys in 2011. Results This analysis included data on 2.9 million adolescents aged 11 to 18 years. There were small increases in coverage for girls, with receipt of ≥1 dose of HPV vaccine reaching 27.1% of ages 11 to 12, 47.9% of ages 13 to 15, and 57.1% of ages 16 to 18 by December 31, 2012. Uptake of ≥1 dose in boys reached ~18% for all age groups. Doses administered showed seasonal variation, with highest uptake before back to school among girls and steady increases in boys after the 2009 ACIP recommendation for permissive use. Doses administered to boys surpassed those administered to girls by September 2012. Among vaccinated girls, more received vaccine at the recommended age of 11 to 12 years in 2011 (74.2%) compared to 2007 (9.9%). In 2011, 27.3% of vaccinated boys received their first dose at age 11 to 12 years. Conclusions HPV vaccination coverage increased among adolescents between 2009 and 2012. However, increases among girls were small, and coverage for boys and girls remained below target levels. PMID:24954170

  14. Synaptic vesicles in electromotoneurones. I. Axonal transport, site of transmitter uptake and processing of a core proteoglycan during maturation.

    PubMed Central

    Kiene, M L; Stadler, H

    1987-01-01

    We were able by using an in vivo pulse-label technique to trace part of the life cycle of a secretory organelle, the acetylcholine-storing synaptic vesicle from electromotoneurones of Torpedo marmorata. This technique uses [35S]sulphate incorporation into the cell bodies of the electromotoneurones which results in radioactive labelling of a synaptic vesicle heparansulphate proteoglycan--a major core component. Vesicles are anterogradely transported in the axons at a fast rate as 'empty' organelles (VP0 population). In the nerve terminal, maturation of the granule to a population (VP1) fully charged with acetylcholine and ATP occurs. Finally after a longer time interval a change to a third population (VP2) is observed. This population is reduced in diameter as compared to VP0 and VP1 suggesting, in agreement with earlier reports, that it has undergone exo-endocytosis. The changes from VP0 to VP1 and VP2 are accompanied by a degradation of the core proteoglycan as measured by gel filtration of the 35S-labelled compound. The results show that vesicles are axonally transported as preformed organelles, exist in the neurone at least in three different populations and that the nerve terminal is the major site of transmitter uptake. Images Fig. 1. Fig. 4. Fig. 6. PMID:2444433

  15. Water structural changes at the proton uptake site (the Thr46-Asp96 domain) in the L intermediate of bacteriorhodopsin

    SciTech Connect

    Yamazaki, Yoichi; Hatanka, Minoru; Kandori, Hideki

    1995-05-30

    Fourier transform infrared spectra of the L intermediate of light-adapted bacteriorhodopsin were examined for recombinant proteins with amino acid substitutions at Thr46 and Asp96. Two O-H stretching vibrational bands of water, at 3607 and 3577 cm{sup -1}, change into stronger H-bonding states in L of the wild type. Thr46{r_arrow}Val substitution abolished these bands in spite of the fact that [3-{sup 18}O]threonine-labeling did not shift with them indicating that they correspond to coordination of the water with Thr46. The two water bands were restored, although with changed frequencies, by an additional Asp96{r_arrow}Asn substitution in Thr46{r_arrow}Val/Asp96{r_arrow}Asn. A single Asp96{r_arrow}Asn substitution abolished the 3607 cm{sup -1} band. Thus, Asp96 also takes part in structural changes in water. The perturbations of these water molecules in the L intermediate displayed a weak correlation with the ratio of intensity change in the two of vibrational bands of the Schiff base mode at 1312 and 1301 cm{sup -1} and the rate for the deprotonation of the Schiff base at the L-to-M reaction of the photocycle. We find, therefore, that the water molecule sin the cytoplasmic Asp96-Thr46 domain, which comprises the site of proton uptake after formation of the M intermediate, undergo structural changes in the L intermediate already. These changes are transmitted to the extracellular domain and the affect interaction of the Schiff base with Asp 85, that is far removed from this region. 32 refs., 7 figs.

  16. Metal uptake by homegrown vegetables – The relative importance in human health risk assessments at contaminated sites

    SciTech Connect

    Augustsson, Anna L.M.; Uddh-Söderberg, Terese E.; Hogmalm, K. Johan; Filipsson, Monika E.M.

    2015-04-15

    Risk assessments of contaminated land often involve the use of generic bioconcentration factors (BCFs), which express contaminant concentrations in edible plant parts as a function of the concentration in soil, in order to assess the risks associated with consumption of homegrown vegetables. This study aimed to quantify variability in BCFs and evaluate the implications of this variability for human exposure assessments, focusing on cadmium (Cd) and lead (Pb) in lettuce and potatoes sampled around 22 contaminated glassworks sites. In addition, risks associated with measured Cd and Pb concentrations in soil and vegetable samples were characterized and a probabilistic exposure assessment was conducted to estimate the likelihood of local residents exceeding tolerable daily intakes. The results show that concentrations in vegetables were only moderately elevated despite high concentrations in soil, and most samples complied with applicable foodstuff legislation. Still, the daily intake of Cd (but not Pb) was assessed to exceed toxicological thresholds for about a fifth of the study population. Bioconcentration factors were found to vary more than indicated by previous studies, but decreasing BCFs with increasing metal concentrations in the soil can explain why the calculated exposure is only moderately affected by the choice of BCF value when generic soil guideline values are exceeded and the risk may be unacceptable. - Highlights: • Uptake of Cd and Pb by lettuce and potatoes increased with soil contamination. • Consumption of homegrown vegetables may lead to a daily Cd intake above TDIs. • The variability in the calculated BCFs is high when compared to previous studies. • Exposure assessments are most sensitive to the choice of BCFs at low contamination.

  17. Comparison of modelled and measured ozone concentrations and meteorology for a site in south-west Sweden: implications for ozone uptake calculations.

    PubMed

    Klingberg, Jenny; Danielsson, Helena; Simpson, David; Pleijel, Håkan

    2008-09-01

    Measurements of ground-level ozone concentrations and meteorology (temperature, vapour pressure deficit (VPD), solar radiation) at the monitoring site Ostad (south-west Sweden) were compared to data from the corresponding grid in the EMEP photo-oxidant model for 1997, 1999 and 2000. The influence of synoptic weather on the agreement between model and measurements was studied. Implications of differences between modelled and observed inputs for ozone flux calculations for wheat and potato were investigated. The EMEP model output of ozone, temperature and VPD correlated well with measurements during daytime. Deviations were larger during the night, especially in calm conditions, attributed to local climatological conditions at the monitoring site deviating from average conditions of the grid. These differences did not lead to significant differences in calculated ozone uptake, which was reproduced remarkably well. The uptake calculations were sensitive to errors in the ozone and temperature input data, especially when including a flux threshold.

  18. Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300

    SciTech Connect

    van Hattem, M G; Santolo, G

    2005-02-23

    Concentrations of eleven potential environmental contaminants (metals) in the blood and retrice feathers of fledged-Hatch Year and adult loggerhead shrikes (Lanius ludovicianus) were examined at Lawrence Livermore National Laboratory's Site 300 and a control site, in San Joaquin and Contra Costa Counties, California. The purpose of this pilot study was to determine, through non-lethal means, if loggerhead shrikes are exposed to metals at Site 300 and whether specific demographic variables (i.e., clutch size, fledgling success, etc.) are affected. Loggerhead shrikes at Site 300 had higher blood concentrations of metals, especially birds on the west side of the site, when compared to control site birds. Metal concentrations in the feathers of control site birds tended to be higher than Site 300 shrikes. Blood concentrations of metals in loggerhead shrikes from both Site 300 and the control site were well below the Most Tolerant Dietary Level (MTDL) for domestic birds for all metals except selenium. Clutch size was similar to other populations but one deformed embryo was discovered in a failed egg. The results of this pilot study suggest further work is needed to understand possible synergistic effects related to other contaminants of concern found at Site 300 and overall population variability.

  19. Tianeptine: 5-HT uptake sites and 5-HT(1-7) receptors modulate memory formation in an autoshaping Pavlovian/instrumental task.

    PubMed

    Meneses, Alfredo

    2002-05-01

    Recent studies using invertebrate and mammal species have revealed that, endogenous serotonin (5-hydroxytryptamine, 5-HT) modulates cognitive processes, particularly learning and memory, though, at present, it is unclear the manner, where, and how long 5-HT systems are involved. Hence in this work, an attempt was made to study the effects of 5-HT endogenous on memory formation, using a 5-HT uptake facilitator (tianeptine) and, selective 5-HT(1-7) receptor antagonists to determine whether 5-HT uptake sites and which 5-HT receptors are involved, respectively. Results showed that post-training tianeptine injection enhanced memory consolidation in an autoshaping Pavlovian/instrumental learning task, which has been useful to detect changes on memory formation elicited by drugs or aging. On interaction experiments, ketanserin (5-HT(1D/2A/2C) antagonist) slightly enhanced tianeptine effects, while WAY 100635 (5-HT(1A) antagonist), SB-224289 (5-HT(1B) inverse agonist), SB-200646 (5-HT(2B/2C) antagonist), ondansetron (5-HT(3) antagonist), GR 127487 (5-HT(4) antagonist), Ro 04-6790 (5-HT(6) antagonist), DR 4004 (5-HT(7) antagonist), or fluoxetine (an inhibitor of 5-HT reuptake) blocked the facilitatory tianeptine effect. Notably, together tianeptine and Ro 04-6790 impaired learning consolidation. Moreover, 5-HT depletion completely reversed the tianeptine effect. Tianeptine also normalized an impaired memory elicited by scopolamine (an antimuscarinic) or dizocilpine (non-competitive glutamatergic antagonist), while partially reversed that induced by TFMPP (5-HT(1B/1D/2A-2C/7) agonist/antagonist). Finally, tianeptine-fluoxetine coadministration had no effect on learning consolidation; nevertheless, administration of an acetylcholinesterase inhibitor, phenserine, potentiated subeffective tianeptine or fluoxetine doses. Collectively, these data confirmed that endogenously 5-HT modulates, via uptake sites and 5-HT(1-7) receptors, memory consolidation, and are consistent with the

  20. Siderophore-mediated iron uptake in fluorescent Pseudomonas: characterization of the pyoverdine-receptor binding site of three cross-reacting pyoverdines.

    PubMed

    Meyer, Jean-Marie; Geoffroy, Valérie A; Baysse, Christine; Cornelis, Pierre; Barelmann, Insa; Taraz, Kambiz; Budzikiewicz, Herbert

    2002-01-15

    Two Pseudomonas fluorescens and one Pseudomonas aeruginosa strains, although producing structurally different pyoverdines, demonstrated highly efficient cross-reactions when tested for pyoverdine-mediated iron uptake. A ferripyoverdine receptor-deficient mutant of the P. aeruginosa strain was unable to use any of the three pyoverdines. Moreover, the three strains presented each a specific outer membrane siderophore-receptor pattern. Thus, the capacity of using heterologous pyoverdines was related not to the presence of supplementary specific ferripyoverdine receptors but to the existence within the respective pyoverdine-peptide chains of a common dipeptide motif which should act as the receptor-binding site for the three pyoverdines. Other pyoverdines sharing the same motif but at another position within the peptide chain were not efficient in iron transport, demonstrating the importance of the spatial position of the binding site. PMID:11795869

  1. Grass species influence on plant N uptake - Determination of atmospheric N deposition to a semi-natural peat bog site using a 15N labelling approach

    NASA Astrophysics Data System (ADS)

    Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

    2014-05-01

    Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. Our study site - a moderately drained raised bog - is surrounded by highly fertilized agricultural land and livestock production. In this study, we used a 15N pool dilution technique called 'Integrated Total Nitrogen Input' (ITNI) to quantify annual deposition of atmospheric N into biomonitoring pots over a two-year period. Since it considers direct N uptake by plants, it was expected to result in higher N input than conventional methods for determination of N deposition (e.g. micrometeorological approaches, bulk N samplers). Using Lolium multiflorum and Eriophorum vaginatum as monitor plants and low, medium and high levels of fertilization, we aimed to simulate increasing N deposition to planted pots and to allocate airborne N after its uptake by the soil-plant system in aboveground biomass, roots and soil. Increasing N fertilization was positively correlated with biomass production of Eriophorum vaginatum, whereas atmospheric plant N uptake decreased and highest airborne N input of 899.8 ± 67.4 µg N d-1 pot-1 was found for low N fertilization. In contrast, Lolium multiflorum showed a clear dependency of N supply on plant N uptake and was highest (688.7 ± 41.4 µg N d-1 pot-1) for highly fertilized vegetation pots. Our results suggest that grass species respond differently to increasing N input. While crop grasses such as Lolium multiflorum take up N according to N availability, species adopted to nutrient-limited conditions like Eriophorum vaginatum show N saturation effects with increasing N supply. Total airborne N input ranged from about 24 to 66 kg N ha-1 yr-1 dependent on the used indicator plant and the amount of added fertilizer. Parallel determination of atmospheric N deposition using a micrometeorological approach

  2. Increasing Healthy Start food and vitamin voucher uptake for low income pregnant women (Early Years Collaborative Leith Pioneer Site)

    PubMed Central

    Mackenzie, Graham; Dougall, Angela

    2016-01-01

    Poverty has a detrimental impact on health and wellbeing. Healthy Start food and vitamin vouchers provide support for low income families across the UK, but at least 25% of eligible women and children miss out. We set out to increase uptake, with an aim of 90% of eligible women and children (n~540 eligible, varying over time) receiving vouchers in the initial team's catchment area by December 2015. Starting with one midwife and one pregnant woman in March 2014 we used the model for improvement to identify ways to improve documentation, sign up, and referral. Weekly data on process measures and monthly data on voucher receipt were plotted on run charts. Comparing medians for January-June 2014 and March-August 2015 there was a 13.3% rise in voucher receipt in Lothian (increase from 313 to 355 women), versus an 8.4% decline for the rest of Scotland (fall from 1688 to 1546 women). Figures varied by team, influenced by staff, family, and area factors. The initial aim proved unrealistic, as signing up a woman for vouchers increases both the numerator and denominator. Accordingly, the percentage uptake has not increased at a regional level (remains at 75%), though the figure for the initiating team (“team 3” in graphs) has increased from 73.0% (January 2014) to 79.0% (November 2015). We have continued testing, achieving recent increases in the number of women referred for welfare rights advice on benefits, tax credits, employment rights, childcare, and debt, securing on average £4,500 per client during 2015/16 (£404k for 89 clients by mid September 2015). This improvement project, part of the Early Years Collaborative in Scotland, has had a measureable impact on pregnant women across Lothian. Success has relied on testing, an electronic maternity record, rapid dissemination of findings through direct engagement with clinical teams, and persistence. Our findings have relevance across the UK, particularly at a time of worsening finances for many families. PMID

  3. Increasing Healthy Start food and vitamin voucher uptake for low income pregnant women (Early Years Collaborative Leith Pioneer Site).

    PubMed

    Mackenzie, Graham; Dougall, Angela

    2016-01-01

    Poverty has a detrimental impact on health and wellbeing. Healthy Start food and vitamin vouchers provide support for low income families across the UK, but at least 25% of eligible women and children miss out. We set out to increase uptake, with an aim of 90% of eligible women and children (n~540 eligible, varying over time) receiving vouchers in the initial team's catchment area by December 2015. Starting with one midwife and one pregnant woman in March 2014 we used the model for improvement to identify ways to improve documentation, sign up, and referral. Weekly data on process measures and monthly data on voucher receipt were plotted on run charts. Comparing medians for January-June 2014 and March-August 2015 there was a 13.3% rise in voucher receipt in Lothian (increase from 313 to 355 women), versus an 8.4% decline for the rest of Scotland (fall from 1688 to 1546 women). Figures varied by team, influenced by staff, family, and area factors. The initial aim proved unrealistic, as signing up a woman for vouchers increases both the numerator and denominator. Accordingly, the percentage uptake has not increased at a regional level (remains at 75%), though the figure for the initiating team ("team 3" in graphs) has increased from 73.0% (January 2014) to 79.0% (November 2015). We have continued testing, achieving recent increases in the number of women referred for welfare rights advice on benefits, tax credits, employment rights, childcare, and debt, securing on average £4,500 per client during 2015/16 (£404k for 89 clients by mid September 2015). This improvement project, part of the Early Years Collaborative in Scotland, has had a measureable impact on pregnant women across Lothian. Success has relied on testing, an electronic maternity record, rapid dissemination of findings through direct engagement with clinical teams, and persistence. Our findings have relevance across the UK, particularly at a time of worsening finances for many families. PMID:27134747

  4. Site-specific conjugation of single domain antibodies to liposomes enhances photosensitizer uptake and photodynamic therapy efficacy

    NASA Astrophysics Data System (ADS)

    Broekgaarden, M.; van Vught, R.; Oliveira, S.; Roovers, R. C.; van Bergen En Henegouwen, P. M. P.; Pieters, R. J.; van Gulik, T. M.; Breukink, E.; Heger, M.

    2016-03-01

    Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested.Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested. Electronic supplementary information (ESI) available: Materials and methods. See DOI: 10.1039/c6nr00014b

  5. Evidence for regional catecholamine uptake and storage sites in the transplanted human heart by positron emission tomography

    SciTech Connect

    Schwaiger, M.; Hutchins, G.D.; Kalff, V.; Rosenspire, K.; Haka, M.S.; Mallette, S.; Deeb, G.M.; Abrams, G.D.; Wieland, D. )

    1991-05-01

    Positron emission tomography in combination with the newly introduced catecholamine analogue ({sup 11}C)hydroxyephedrine (({sup 11}C)HED) enables the noninvasive delineation of sympathetic nerve terminals of the heart. To address the ongoing controversy over possible reinnervation of the human transplant, 5 healthy control subjects and 11 patients were studied after cardiac transplant by this imaging approach. Regional ({sup 11}C)HED retention was compared to regional blood flow as assessed by rubidium-82. Transplant patients were divided into two groups. Group I had recent (less than 1 yr, 4.4 +/- 2.3 mo) surgery, while group II patients underwent cardiac transplantation more than 2 yr before imaging (3.5 +/- 1.3 yr). ({sup 11}C)HED retention paralleled blood flow in normals, but was homogeneously reduced in group I. In contrast, group II patients revealed heterogeneous ({sup 11}C)HED retention, with increased uptake in the proximal anterior and septal wall. Quantitative evaluation of ({sup 11}C)HED retention revealed a 70% reduction in group I and 59% reduction in group II patients (P less than 0.001). In group II patients, ({sup 11}C)HED retention reached 60% of normal in the proximal anterior wall. These data suggest the presence of neuronal tissue in the transplanted human heart, which may reflect regional sympathetic reinnervation.

  6. SITE SITE DISTURBANCE EFFECTS ON A CLAY SOIL UNDER PINUS RADIATA - ROOT BIOMASS, MYCORRHIZAL COLONISATION, 15AMMONIUM UPTAKE, AND FOLIAR NUTRIENT LEVELS

    EPA Science Inventory

    Timber harvesting can result in adverse physical, chemical and biological alterations to soil. The objective of this study was to examine the effects of site disturbance to determine the extent and duration of possible harvesting impacts on soil chemical and biological propertie...

  7. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules

    PubMed Central

    Davidge, Kelly S; Singh, Sandip; Bowman, Lesley AH; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and •NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify •NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, •NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site. PMID:26478812

  8. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules.

    PubMed

    Boron, Ignacio; Bustamante, Juan Pablo; Davidge, Kelly S; Singh, Sandip; Bowman, Lesley Ah; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify (•)NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, (•)NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.

  9. Did we choose the best one? A new site selection approach based on exposure and uptake potential for waste incineration.

    PubMed

    Demirarslan, K Onur; Korucu, M Kemal; Karademir, Aykan

    2016-08-01

    Ecological problems arising after the construction and operation of a waste incineration plant generally originate from incorrect decisions made during the selection of the location of the plant. The main objective of this study is to investigate how the selection method for the location of a new municipal waste incineration plant can be improved by using a dispersion modelling approach supported by geographical information systems and multi-criteria decision analysis. Considering this aim, the appropriateness of the current location of an existent plant was assessed by applying a pollution dispersion model. Using this procedure, the site ranking for a total of 90 candidate locations and the site of the existing incinerator were determined by a new location selection practice and the current place of the plant was evaluated by ANOVA and Tukey tests. This ranking, made without the use of modelling approaches, was re-evaluated based on the modelling of various variables, including the concentration of pollutants, population and population density, demography, temporality of meteorological data, pollutant type, risk formation type by CALPUFF and re-ranking the results. The findings clearly indicate the impropriety of the location of the current plant, as the pollution distribution model showed that its location was the fourth-worst choice among 91 possibilities. It was concluded that the location selection procedures for waste incinerators should benefit from the improvements obtained by the articulation of pollution dispersion studies combined with the population density data to obtain the most suitable location.

  10. Did we choose the best one? A new site selection approach based on exposure and uptake potential for waste incineration.

    PubMed

    Demirarslan, K Onur; Korucu, M Kemal; Karademir, Aykan

    2016-08-01

    Ecological problems arising after the construction and operation of a waste incineration plant generally originate from incorrect decisions made during the selection of the location of the plant. The main objective of this study is to investigate how the selection method for the location of a new municipal waste incineration plant can be improved by using a dispersion modelling approach supported by geographical information systems and multi-criteria decision analysis. Considering this aim, the appropriateness of the current location of an existent plant was assessed by applying a pollution dispersion model. Using this procedure, the site ranking for a total of 90 candidate locations and the site of the existing incinerator were determined by a new location selection practice and the current place of the plant was evaluated by ANOVA and Tukey tests. This ranking, made without the use of modelling approaches, was re-evaluated based on the modelling of various variables, including the concentration of pollutants, population and population density, demography, temporality of meteorological data, pollutant type, risk formation type by CALPUFF and re-ranking the results. The findings clearly indicate the impropriety of the location of the current plant, as the pollution distribution model showed that its location was the fourth-worst choice among 91 possibilities. It was concluded that the location selection procedures for waste incinerators should benefit from the improvements obtained by the articulation of pollution dispersion studies combined with the population density data to obtain the most suitable location. PMID:27354016

  11. An evaluation of the regional acid deposition model surface module for ozone uptake at three sites in the San Joaquin Valley of California

    NASA Technical Reports Server (NTRS)

    Massman, W. J.; Pederson, J.; Delany, A.; Grantz, D.; Hertog, G. Den; Neumann, H. H.; Oncley, S. P.; Pearson, R., Jr.; Shaw, R. H.

    1994-01-01

    Plants and soils act as major sinks for the destruction of tropospheric ozone, especially during daylight hours when plant stomata open and are thought to provide the dominant pathway for the uptake of ozone. The present study, part of the California Ozone Deposition Experiment, compares predictions of the regional acid deposition model ozone surface conductance module with surface conductance data derived from eddy covariance measurements of ozone flux taken at a grape, a cotton, and a grassland site in the San Joaquin Valley of California during the summer of 1991. Results indicate that the model (which was developed to provide long-term large-area estimates for the eastern United States) significantly overpredicts the surface conductance at all times of the day for at least two important types of plant cover of the San Joaquin Valley and that it incorrectly partitions the ozone flux between transpiring and nontranspiring components of the surface at the third site. Consequently, the model either overpredicts or inaccurately represents the observed deposition velocities. Other results indicate that the presence of dew does not reduce the rate of ozone deposition, contradicting to model assumptions, and that model assumptions involving the dependency of stomata upon environmental temperature are unnecessary. The effects of measurement errors and biases, arising from the presence of the roughness sublayer and possible photochemical reactions, are also discussed. A simpler model for ozone surface deposition (at least for the San Joaquin Valley) is proposed and evaluated.

  12. GABA localization in the nematode Ascaris

    SciTech Connect

    Guastella, J.

    1988-01-01

    A histochemical approach was used to examine the distribution of GABA-associated neurons in the nematode Ascaris, an organism whose small number of morphologically simple neurons make it an excellent preparation for analyzing neuronal phenotypes. Two GABAergic markers were examined: GABA-like immunoreactivity (GLIR), a marker for endogenous stores of GABA; and ({sup 3}H)-GABA uptake, a marker for GABA uptake sites. Strong GLIR was present in the cell bodies, neurites and commissures of dorsal and ventral inhibitory motorneurons present in this region. Strong GLIR was also present in the cell bodies and processes of the four RME neurons in the nerve ring and in several other ganglionic neurons. Staining was absent in excitatory motorneurons, in ventral cord interneurons and in muscle cells and hypodermis. GABA uptake sites were found in single neural processes in both the ventral and dorsal nerve cords. ({sup 3}H)-GABA labeling was also observed in the other two RME cells and several other cephalic neurons. Four putative cholinergic excitatory motorneurons in the retrovesicular ganglion (RVG) were heavily labeled. Ventral and dorsal nerve cord inhibitory motorneurons did not take up ({sup 3}H)-GABA. Labeling of the ventral cord excitatory motorneuron somata and cell bodies was at or slightly above background. Heavy labeling of muscle cells was also observed.

  13. Cadmium and zinc uptake by volunteer willow species and elder rooting in polluted dredged sediment disposal sites.

    PubMed

    Vandecasteele, Bart; De Vos, Bruno; Tack, Filip M G

    2002-11-01

    Salix species and Sambucus nigra L. (elder) naturally invade dredged sediment landfills and are commonly encountered on substrates contaminated with heavy metals. Foliar concentrations of Cd and Zn in four Salix species and elder were explored in the field. Metal contents in dredged sediment derived soils were elevated compared to baseline concentration levels reported for Flanders. To evaluate foliar concentrations, reference data were compiled from observations in nurseries, young plantations and unpolluted sites with volunteer willow vegetation. Willows grown on polluted dredged sediment landfills showed elevated foliar Cd and Zn concentrations (>6.6 mg Cd/kg DW and >700 mg Zn/kg DW). This was not the case for elder. For willow, a significant relation was found between soil total Zn or Cd and foliar Zn or Cd, regardless of age, species, or clone. Willows proved to be useful bioindicators. Results indicated a possible threat in long-term habitat development of willow brushwood from transfer of Cd and Zn to the food web.

  14. Random and site-specific mutagenesis of the Helicobacter pylori ferric uptake regulator provides insight into Fur structure-function relationships.

    PubMed

    Gilbreath, Jeremy J; Pich, Oscar Q; Benoit, Stéphane L; Besold, Angelique N; Cha, Jeong-Heon; Maier, Robert J; Michel, Sarah L J; Maynard, Ernest L; Merrell, D Scott

    2013-07-01

    The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wild-type (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3) respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in manganese-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2 and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein.

  15. Random and site-specific mutagenesis of the Helicobacter pylori ferric uptake regulator provides insight into Fur structure-function relationships.

    PubMed

    Gilbreath, Jeremy J; Pich, Oscar Q; Benoit, Stéphane L; Besold, Angelique N; Cha, Jeong-Heon; Maier, Robert J; Michel, Sarah L J; Maynard, Ernest L; Merrell, D Scott

    2013-07-01

    The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wild-type (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3) respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in manganese-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2 and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein. PMID:23710935

  16. Random and Site-Specific Mutagenesis of the Helicobacter pylori Ferric Uptake Regulator Provides Insight into Fur Structure-Function Relationships

    PubMed Central

    Gilbreath, Jeremy J.; Pich, Oscar Q.; Benoit, Stéphane L.; Besold, Angelique N.; Cha, Jeong-Heon; Maier, Robert J.; Michel, Sarah L.J.; Maynard, Ernest L.; Merrell, D. Scott

    2013-01-01

    Summary The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wildtype (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T, and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3), respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in iron-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2, and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein. PMID:23710935

  17. 3,4-Methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine destroy serotonin terminals in rat brain: quantification of neurodegeneration by measurement of (/sup 3/H)paroxetine-labeled serotonin uptake sites

    SciTech Connect

    Battaglia, G.; Yeh, S.Y.; O'Hearn, E.; Molliver, M.E.; Kuhar, M.J.; De Souza, E.B.

    1987-09-01

    This study examines the effects of repeated systemic administration (20 mg/kg s.c., twice daily for 4 days) of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) on levels of brain monoamines, their metabolites and on the density of monoamine uptake sites in various regions of rat brain. Marked reductions (30-60%) in the concentration of 5-hydroxyindoleacetic acid were observed in cerebral cortex, hippocampus, striatum, hypothalamus and midbrain at 2 weeks after a 4-day treatment regimen of MDMA or MDA; less consistent reductions in serotonin (5-HT) content were observed in these brain regions. In addition, both MDMA and MDA caused comparable and substantial reductions (50-75%) in the density of (/sup 3/H)paroxetine-labeled 5-HT uptake sites in all brain regions examined. In contrast, neither MDMA nor MDA caused any widespread or long-term changes in the content of the catecholaminergic markers (i.e., norepinephrine, dopamine, 3,4 dihydroxyphenylacetic acid and homovanillic acid) or in the number of (/sup 3/H)mazindol-labeled norepinephrine or dopamine uptake sites in the brain regions examined. These data demonstrate that MDMA and MDA cause long-lasting neurotoxic effects with respect to both the functional and structural integrity of serotonergic neurons in brain. Furthermore, our measurement of reductions in the density of 5-HT uptake sites provides a means for quantification of the neurodegenerative effects of MDMA and MDA on presynaptic 5-HT terminals.

  18. Site-specific conjugation of monodispersed DOTA-PEGn to a thiolated diabody reveals the effect of increasing peg size on kidney clearance and tumor uptake with improved 64-copper PET imaging.

    PubMed

    Li, Lin; Crow, Desiree; Turatti, Fabio; Bading, James R; Anderson, Anne-Line; Poku, Erasmus; Yazaki, Paul J; Carmichael, Jenny; Leong, David; Wheatcroft, David; Wheatcroft, Michael P; Raubitschek, Andrew A; Hudson, Peter J; Colcher, David; Shively, John E

    2011-04-20

    Optimal PET imaging of tumors with radiolabeled engineered antibodies requires, among other parameters, matching blood clearance and tumor uptake with the half-life of the engineered antibody. Although diabodies have favorable molecular sizes (50 kDa) for rapid blood clearance (t(1/2) = 30-60 min) and are bivalent, thereby increasing tumor uptake, they exhibit substantial kidney uptake as their major route of clearance, which is especially evident when they are labeled with the PET isotope (64)Cu (t(1/2) = 12 h). To overcome this drawback, diabodies may be conjugated to PEG, a modification that increases the apparent molecular size of the diabody and reduces kidney uptake without adversely affecting tumor uptake or the tumor to blood ratio. We show here that site-specific attachment of monodispersed PEGn of increasing molecular size (n = 12, 24, and 48) can uniformly increase the apparent molecular size of the PEG-diabody conjugate, decrease kidney uptake, and increase tumor uptake, the latter due to the increased residence time of the conjugate in the blood. Since the monodispersed PEGs were preconjugated to the chelator DOTA, the conjugates were able to bind radiometals such as (111)In and (64)Cu that can be used for SPECT and PET imaging, respectively. To allow conjugation of the DOTA-PEG to the diabody, the DOTA-PEG incorporated a terminal cysteine conjugated to a vinyl sulfone moiety. In order to control the conjugation chemistry, we have engineered a surface thiolated diabody that incorporates two cysteines per monomer (four per diabody). The thiolated diabody was expressed and purified from bacterial fermentation and only needs to be reduced prior to conjugation to the DOTA-PEGn-Cys-VS. This novel imaging agent (a diabody with DOTA-PEG48-Cys-VS attached to introduced thiols) gave up to 80%ID/g of tumor uptake with a tumor to blood ratio (T/B) of 8 at 24 h when radiolabeled with (111)In and 37.9% ID/g of tumor uptake (T/B = 8) at 44 h when radiolabeled with

  19. Uptake of strontium by chamisa (Chrysothamnus nauseosus) shrub plants growing over a former liquid waste disposal site at Los Alamos National Laboratory

    SciTech Connect

    Fresquez, P.R.; Foxx, T.S.; Naranjo, L. Jr.

    1996-06-01

    A major concern of managers at low-level waste burial site facilities is that plant roots may translocate contaminants up to the soil surface. This study investigates the uptake of strontium ({sup 90}Sr), a biologically mobile element, by chamisa (Chrysothamnus nauseosus), a deep-rooted shrub plant, growing in a former liquid waste disposal site (Solid Waste Management Unit [SWMU] 10-003[c]) at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Surface soil samples were also collected from below (understory) and between (interspace) shrub canopies. Both chamisa plants growing over SWMU 10-003(c) contained significantly higher concentrations of {sup 90}Sr than a control plant--one plant, in particular, contained 3.35 x 10{sup 6} Bq kg{sup {minus}1} ash (9.05 x 10{sup 4} pCi g{sup {minus}1} ash) in top-growth material. Similarly, soil surface samples collected underneath and between plants contained {sup 90}Sr concentrations above background and LANL screening action levels (> 218 Bq kg{sup {minus}1} dry [5.90 pCi g{sup {minus}1} dry]); this probably occurred as a result of chamisa plant leaf fall contaminating the soil understory area followed by water and/or winds moving {sup 90}Sr to the soil interspace areas. Although some soil surface migration of {sup 90}Sr from SWMU 10-003(c) has occurred, the level of {sup 90}Sr in sediments collected downstream of SWMU 10-003(c) at the LANL boundary was still within regional (background) concentrations.

  20. Roles of uptake, biotransformation, and target site sensitivity in determining the differential toxicity of chlorpyrifos to second to fourth instar Chironomous riparius (Meigen)

    USGS Publications Warehouse

    Buchwalter, D.B.; Sandahl, J.F.; Jenkins, J.J.; Curtis, L.R.

    2004-01-01

    Early life stages of aquatic organisms tend to be more sensitive to various chemical contaminants than later life stages. This research attempted to identify the key biological factors that determined sensitivity differences among life stages of the aquatic insect Chironomous riparius. Specifically, second to fourth instar larvae were exposed in vivo to both low and high waterborne concentrations of chlorpyrifos to examine differences in accumulation rates, chlorpyrifos biotransformation, and overall sensitivity among instars. In vitro acetylcholinesterase (AChE) assays were performed with chlorpyrifos and the metabolite, chlorpyrifos-oxon, to investigate potential target site sensitivity differences among instars. Earlier instars accumulated chlorpyrifos more rapidly than later instars. There were no major differences among instars in the biotransformation rates of chlorpyrifos to the more polar metabolites, chlorpyrifos-oxon, and chlorpyridinol (TCP). Homogenate AChE activities from second to fourth instar larvae were refractory to chlorpyrifos, even at high concentrations. In contrast, homogenate AChE activities were responsive in a dose-dependent manner to chlorpyrifos-oxon. In general, it appeared that chlorpyrifos sensitivity differences among second to fourth instar C. riparius were largely determined by differences in uptake rates. In terms of AChE depression, fourth instar homogenates were more sensitive to chlorpyrifos and chlorpyrifos-oxon than earlier instars. However, basal AChE activity in fourth instar larvae was significantly higher than basal AChE activity in second to third instar larvae, which could potentially offset the apparent increased sensitivity to the oxon. ?? 2003 Elsevier B.V. All rights reserved.

  1. [C-11]{beta}CNT: A new monoamine uptake ligand for studying serotonin and dopamine transporter sites in the living brain with PET

    SciTech Connect

    Mulholland, G.K.; Zheng, Q.H.; Zhou, F.C.

    1996-05-01

    There is considerable interest in measuring serotonin (5HT) and dopamine (DA) function in the human brain. Altered levels of 5HT and DA are recognized in drug abuse, neurotoxicities, psychiatric disorders, and neurodegenerative conditions including Alzheimer`s and Parkinson`s disease. Several phenyltropane analogs of cocaine bind tightly to both DA and 5HT uptake proteins. We have made a new agent from this class called {beta}CNT, 2{beta}-carboxymethyl-3{beta}-(2-naphthyl)-tropane, the isosteric O-for-CH{sub 2} analog of a compound reported to have among the highest measured affinities for DA and 5HT transporters and studied its in vivo brain distributions in animals for the first time. Optically pure {beta}CNT was made from cocaine, and labeled at the O-methyl position by esterification of {beta}CNT-acid with [C-11]CH{sub 3}OTfl under conditions similar to Wilson`s. HPLC-purified (99+%) final products (15-50% eob yield from CO{sub 2}, 40 min synth) had specific activities 0.1-1.2 Ci/{mu}mol at the time of injection. Preliminary [C-11]{beta}{beta}CNT rodent distribution showed very high brain uptake (3% ID at 60 min) and localization (striat: fr cort: hypo: cer: blood, 11: 5: 4: 1: 06). {beta}CNT-PET studies in juvenile pigs (5-20 mCi, 20-35 kg) found rapid brain uptake, and prominent retention (85 min) in midbrain, anterior brainstem and striatum, followed by cortex and olfactory bulb. Paroxetine pretreatment (5HT uptake blocker, 2mg/kg), diminished retention in most brain areas; nomifensine (DA/NE uptake blocker, 6 mg/kg) reduced striatum selectively. Direct comparisons of [C-11]{beta}CNT with other PET transporter radioligands {beta}CFT, {beta}CIT, and {beta}CTT (RTI-32) in the same pig found {beta}CNT had highest overall brain uptake among the agents. These initial results suggest {beta}CNT has favorable properties for imaging both 5HT and DA transporters in vivo, and further evaluation of its potential as a human PET agent is warranted.

  2. Binding of [(3)H]lysergic acid diethylamide to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites in platelets from healthy children, adolescents and adults.

    PubMed

    Sigurdh, J; Spigset, O; Allard, P; Mjörndal, T; Hägglöf, B

    1999-11-01

    Possible age effects on binding of [(3)H]lysergic acid diethylamide ([(3)H]LSD) to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites were studied in platelets from healthy children (11-12 years of age), adolescents (16-17 years of age) and adults. Significant overall age effects were found both for the number of binding sites (B(max)) for [(3)H]LSD binding (p < 0.001), the affinity constant (K(d)) for [(3)H]LSD binding (p < 0.001), B(max) for [(3)H]paroxetine binding (p < 0.001) and K(d) for [(3)H] paroxetine binding (p = 0.006). In general, there was a decrease in B(max) with increasing age, which predominantly occurred between the ages 11-12 years and 16-17 years for the 5-HT(2A) receptor, and after 16-17 years of age for the serotonin uptake site. These developmental changes might have an impact on the effect of treatment with serotonergic drugs in children and adolescents. When the platelet serotonin variables investigated are employed in studies in children or adolescents, age matching or, alternatively, introduction of age control in the statistical analysis should be performed.

  3. Significant enhancement of gas uptake capacity and selectivity via the judicious increase of open metal sites and Lewis basic sites within two polyhedron-based metal-organic frameworks.

    PubMed

    Liu, Bing; Yao, Shuo; Shi, Chao; Li, Guanghua; Huo, Qisheng; Liu, Yunling

    2016-02-21

    Two new isomorphous polyhedron-based MOFs ( and ), with dual functionalities of OMSs and LBSs, have been synthesized by using the SBB strategy. By judiciously avoiding the DABCO axial ligand, possesses more OMSs than , and exhibits a significant enhancement of CO2 uptake capacity 210 versus 162 cm(3) g(-1) for at 273 K under 1 bar.

  4. Identification of gamma-aminobutyric acid and its binding sites in Caenorhabditis elegans

    SciTech Connect

    Schaeffer, J.M.; Bergstrom, A.R.

    1988-01-01

    Gamma-aminobutyric acid (GABA), glutamate decarboxylase and GABA-transaminase were identified in the nematode Caenorhabditis elegans. The concentration of GABA in C. elegans is approximately 10-fold lower than the concentration of GABA in rat brain. Glutamate decarboxylase and GABA-transaminase, the GABA anabolic and catabolic enzymes, are also present in C. elegans. Crude membrane fractions were prepared from C. elegans and used to study specific (/sup 3/H) GABA binding sites. GABA binds to C. elegans membranes with high affinity and low capacity. Muscimol is a competitive inhibitor of specific GABA binding with a K/sub I/ value of 120 nM. None of the other GABA agonists or antagonists inhibited greater than 40% of the specific GABA binding at concentrations up to 10/sup -4/M. Thirteen spider venoms were examined as possible GABA agonists or antagonists, the venom from Calilena agelenidae inhibits specific GABA binding with a K/sub I/ value of 6 nl/ml. These results suggest that GABA has a physiological role as a neurotransmitter in C. elegans.

  5. Biaryl analogues of conformationally constrained tricyclic tropanes as potent and selective norepinephrine reuptake inhibitors: synthesis and evaluation of their uptake inhibition at monoamine transporter sites.

    PubMed

    Zhou, Jia; Zhang, Ao; Kläss, Thomas; Johnson, Kenneth M; Wang, Cheng Z; Ye, Yan Ping; Kozikowski, Alan P

    2003-05-01

    A series of novel conformationally constrained tricyclic tropane derivatives containing a biaryl moiety, (Z)-9-(biarylylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes, were synthesized and evaluated for their ability to inhibit reuptake of dopamine (DA), serotonin (5-HT), and norepinephrine (NE) by the DA, 5-HT, and NE transporters. Most of the compounds containing a methoxycarbonyl substituent at C-10 exhibit moderate to high inhibitory activity at the NET but lower activity at the DAT and SERT. Among these new compounds, some potent, NET-selective ligands were identified. The p-methoxy derivative 11a has a K(i) value of 39 nM for uptake inhibition at the NET and moderate to high selectivity over the SERT (100-fold) and the DAT (20-fold). Compound 11f exhibits a remarkable potency (K(i) = 9.7 nM) at the NET and a 25-fold selectivity over both the SERT and the DAT. Analogue 23 containing a thiophene ring as a bioisosteric replacement of the phenyl ring Ar(1) displays a high activity (K(i) = 10.3 nM) for the NET and similar selectivity over the SERT (50-fold) and the DAT (37-fold). The selectivity profile of biaryl analogues differs from that of the monoaryl series, as most members of that series display excellent potency at and selectivity for the SERT (J. Med. Chem. 2002, 45, 1930). This finding suggests that the different shape and size of the lipophilic recognition pocket that encompasses the aryl ring(s) of these tropanes are major determinants of a ligand's transporter activity at either the NET or the SERT. Some of the compounds in this series may also be valuable in sorting out the contribution of the individual transporters to cocaine's reinforcing properties.

  6. An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

    PubMed

    Atwal, O S; Viel, L; Minhas, K J

    1990-07-01

    The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung.

  7. An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

    PubMed

    Atwal, O S; Viel, L; Minhas, K J

    1990-07-01

    The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung. PMID:2390765

  8. Rates and Determinants of Uptake and Use of an Internet Physical Activity and Weight Management Program in Office and Manufacturing Work Sites in England: Cohort Study

    PubMed Central

    Hurling, Robert; Bataveljic, Ogi; Fairley, Bruce W; Hurst, Tina L; Murray, Peter; Rennie, Kirsten L; Tomkins, Chris E; Finn, Anne; Cobain, Mark R; Pearson, Dympna A; Foreyt, John P

    2008-01-01

    Background Internet-based physical activity (PA) and weight management programs have the potential to improve employees’ health in large occupational health settings. To be successful, the program must engage a wide range of employees, especially those at risk of weight gain or ill health. Objective The aim of the study was to assess the use and nonuse (user attrition) of a Web-based and monitoring device–based PA and weight management program in a range of employees and to determine if engagement with the program was related to the employees’ baseline characteristics or measured outcomes. Methods Longitudinal observational study of a cohort of employees having access to the MiLife Web-based automated behavior change system. Employees were recruited from manufacturing and office sites in the North West and the South of England. Baseline health data were collected, and participants were given devices to monitor their weight and PA via data upload to the website. Website use, PA, and weight data were collected throughout the 12-week program. Results Overall, 12% of employees at the four sites (265/2302) agreed to participate in the program, with 130 men (49%) and 135 women (51%), and of these, 233 went on to start the program. During the program, the dropout rate was 5% (11/233). Of the remaining 222 Web program users, 173 (78%) were using the program at the end of the 12 weeks, with 69% (153/222) continuing after this period. Engagement with the program varied by site but was not significantly different between the office and factory sites. During the first 2 weeks, participants used the website, on average, 6 times per week, suggesting an initial learning period after which the frequency of website log-in was typically 2 visits per week and 7 minutes per visit. Employees who uploaded weight data had a significant reduction in weight (−2.6 kg, SD 3.2, P< .001). The reduction in weight was largest for employees using the program’s weight loss mode (−3

  9. Application of ground bone and sheep manure on soils from two contaminated sites and influence on oat growth, uranium and radium uptake and translocation

    NASA Astrophysics Data System (ADS)

    Abreu, M. M.; Pacheco, A.; Santos, E.; Magalhães, M. C. F.

    2012-04-01

    Past radium and uranium exploitation and processing in Urgeiriça mine and radium processing in Barracão (centre-north of Portugal) led to soils and waters contamination. Most of the soils, located in rural areas, are cultivated for vegetables, fruit trees, and/or pasturage, and the waters used for soils irrigation. The objective of this work was to evaluate the capacity of organic amendments and hydroxiapatite to reduce the soil available fraction of Utotal and 226Ra in soils of two areas after four months of incubation. Influence on oat growth, uranium and radium uptake and translocation was also studied. Pot experiments, under controlled conditions, were undertaken during four months of incubation at 70% of the soil water-holding capacity. Urgeiriça (Urg) and Barracão (Brc) soils containing large concentrations of Utotal (635 and 189 mg/kg, respectively), and 226Ra (2310 and 1770 Bq/kg, respectively) were used. The available fraction of these elements, extracted with ammonium acetate, corresponds to: 90 and 20% of total concentration of uranium and radium, respectively, for Urgeiriça soil, and 19 and 43% of total concentration of uranium and radium, respectively, for Barracão soil. Fine ground bone (FB), sheep manure (OM), and vermicompost (V) single or mixtures were used as amendments. Control (soil) and treatments were made in triplicate: (T1) soil+96 g FB/kg of soil; (T2) soil+168 g OM/kg of soil; (T3) soil+168 g OM/kg of soil+96 g FB/kg of soil; (T4) soil+168 g V/kg of soil. After incubation, soil subsamples were analysed for pH, electric conductivity (EC), and available fractions of Utotal and 226Ra. The remaining soils were used for oat (Avena sativa L.) cultivation. Soils had pH 5.15 (Urg) and 6.04 (Brc), and EC 57.3 µS/cm (Urg) and 36.3 µS/cm (Brc). After incubation soil pH increased to a maximum of 6.82 (Urg) and 7.10 (Brc) in amended samples, and EC showed a large increase (15-19 times) when compared to the control. A decrease of the available

  10. Binding of [3H]paroxetine to serotonin uptake sites and of [3H]lysergic acid diethylamide to 5-HT2A receptors in platelets from women with premenstrual dysphoric disorder during gonadotropin releasing hormone treatment.

    PubMed

    Bixo, M; Allard, P; Bäckström, T; Mjörndal, T; Nyberg, S; Spigset, O; Sundström-Poromaa, I

    2001-08-01

    Changes in serotonergic parameters have been reported in psychiatric conditions such as depression but also in the premenstrual dysphoric disorder (PMDD). In addition, hormonal effects on serotonergic activity have been established. In the present study, binding of [3H]paroxetine to platelet serotonin uptake sites and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors were studied in patients with PMDD treated with a low dose of a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and compared to controls. The PMDD patients were relieved of premenstrual symptoms like depression and irritability during buserelin treatment. The number of [3H]paroxetine binding sites (Bmax) were significantly higher in the follicular phase in untreated PMDD patients compared to controls. When treated with buserelin the difference disappeared. No differences in [3H]LSD binding between the three groups were shown. The present study demonstrated altered platelet [3H]paroxetine binding characteristics in women with PMDD compared to controls. Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low dose of buserelin. The results are consistent with the hypothesis that changes in serotonergic transmission could be a trait in the premenstrual dysphoric disorder.

  11. Potential Moderating Effects of Selenium on Mercury Uptake and Selenium:Mercury Molar Ratios in Fish From Oak Ridge and Savannah River Site - 12086

    SciTech Connect

    Burger, Joanna; Gochfeld, Michael; Donio, Mark; Jeitner, Christian; Pittfield, Taryn

    2012-07-01

    Mercury contamination is an important remediation issue at the U.S. Department of Energy's (DOE) Oak Ridge Reservation and to a lesser extent at other DOE sites because of the hazard it presents, potential consequences to humans and eco-receptors, and completed pathways, to offsite receptors. Recent work has emphasized that selenium might ameliorate the toxicity of mercury, and we examine the selenium:mercury (Se:Hg) molar ratios in fish from Oak Ridge, and compare them to Se:Hg molar ratios in fish from the Savannah River. Selenium/mercury molar ratios varied considerably among and within fish species. There was considerable variation in the molar ratios for individual fish (as opposed to mean ratios by species) for freshwater fish from both sites. The inter-individual variation in molar ratios indicates that such that the molar ratios of mean Se and Hg concentrations may not be representative. Even for fish species with relatively low mercury levels, some individual fish have molar ratios less than unity, the value sometime thought to be protective. Selenium levels varied narrowly regardless of fish size, consistent with homeostatic regulation of this essential trace element. The data indicate that considerable attention will need to be directed toward variations and variances, as well as the mechanisms of the interaction of selenium and mercury, before risk assessment and risk management policies can use this information to manage mercury pollution and risk. Even so, if there are high levels of selenium in the fish from Poplar Creek on Oak Ridge, then the potential exists for some amelioration of adverse health effects, on the fish themselves, predators that eat them, and people who consume them. This work will aid DOE because it will allow managers and scientists to understand another aspect that affects fate and transport of mercury, as well as the potential effects of methylmercury in fish for human and ecological receptors. The variability within fish

  12. Excitant amino acid projections from rat amygdala and thalamus to nucleus accumbens

    SciTech Connect

    Robinson, T.G.; Beart, P.M.

    1988-04-01

    High affinity uptake of D-(/sup 3/H)aspartate, (/sup 3/H)choline and (/sup 3/H)GABA was examined in synaptosomal-containing preparations of rat nucleus accumbens septi 7 to 10 days after unilateral or bilateral N-methyl-D-aspartate lesions confined to the parataenial nucleus of the thalamus or the basolateral nucleus of the amygdala. Uptake of both D-(/sup 3/H)aspartate and (/sup 3/H)choline was significantly reduced (11% and 14% less than control, respectively) by unilateral lesion of the thalamus, whereas (/sup 3/H)GABA uptake was unaffected. Bilateral thalamic lesions significantly reduced D-(/sup 3/H)aspartate uptake (11% less than control) into homogenates of the nucleus accumbens, whilst (/sup 3/H)GABA uptake was unaltered. D-(/sup 3/H)aspartate uptake was significantly reduced (26% less than control) following unilateral lesion of the amygdala, whereas both (/sup 3/H)GABA and (/sup 3/H)choline uptake were unaffected. Bilateral amygdaloid lesions significantly increased D-(/sup 3/H)aspartate uptake (39% greater than control), whilst uptake of (/sup 3/H)GABA was not affected. The results implicate glutamate and/or aspartate as putative neurotransmitters in afferent projections from the basolateral amygdala and the parataenial thalamus to the nucleus accumbens. Thalamic afferents to the nucleus accumbens may also utilize acetylcholine as their transmitter.

  13. Cystathionine γ lyase-hydrogen sulfide increases peroxisome proliferator-activated receptor γ activity by sulfhydration at C139 site thereby promoting glucose uptake and lipid storage in adipocytes.

    PubMed

    Cai, Junyan; Shi, Xiaoqin; Wang, Huamin; Fan, Jinghui; Feng, Yongliang; Lin, Xianjuan; Yang, Jichun; Cui, Qinghua; Tang, Chaoshu; Xu, Guoheng; Geng, Bin

    2016-05-01

    Adipocytes express the cystathionine γ lyase (CSE)-hydrogen sulfide (H2S) system. CSE-H2S promotes adipogenesis but ameliorates adipocyte insulin resistance. We investigated the mechanism of how CSE-H2S induces these paradoxical effects. First, we confirmed that an H2S donor or CSE overexpression promoted adipocyte differentiation. Second, we found that H2S donor inhibited but CSE inhibition increased phosphodiesterase (PDE) activity. H2S replacing isobutylmethylxanthine in the differentiation program induced adipocyte differentiation in part. Inhibiting PDE activity by H2S induced peroxisome proliferator activated receptor γ (PPARγ) protein and mRNA expression. Of note, H2S directly sulfhydrated PPARγ protein. Sulfhydrated PPARγ increased its nuclear accumulation, DNA binding activity and adipogenesis gene expression, thereby increasing glucose uptake and lipid storage, which were blocked by the desulfhydration reagent DTT. H2S induced PPARγ sulfhydration, which was blocked by mutation of the C139 site of PPARγ. In mice fed a high-fat diet (HFD) for 4 weeks, the CSE inhibitor decreased but H2S donor increased adipocyte numbers. In obese mice fed an HFD for 13 weeks, H2S treatment increased PPARγ sulfhydration in adipose tissues and attenuated insulin resistance but did not increase obesity. In conclusion, CSE-H2S increased PPARγ activity by direct sulfhydration at the C139 site, thereby changing glucose into triglyceride storage in adipocytes. CSE-H2S-mediated PPARγ activation might be a new therapeutic target for diabetes associated with obesity. PMID:26946260

  14. Cystathionine γ lyase-hydrogen sulfide increases peroxisome proliferator-activated receptor γ activity by sulfhydration at C139 site thereby promoting glucose uptake and lipid storage in adipocytes.

    PubMed

    Cai, Junyan; Shi, Xiaoqin; Wang, Huamin; Fan, Jinghui; Feng, Yongliang; Lin, Xianjuan; Yang, Jichun; Cui, Qinghua; Tang, Chaoshu; Xu, Guoheng; Geng, Bin

    2016-05-01

    Adipocytes express the cystathionine γ lyase (CSE)-hydrogen sulfide (H2S) system. CSE-H2S promotes adipogenesis but ameliorates adipocyte insulin resistance. We investigated the mechanism of how CSE-H2S induces these paradoxical effects. First, we confirmed that an H2S donor or CSE overexpression promoted adipocyte differentiation. Second, we found that H2S donor inhibited but CSE inhibition increased phosphodiesterase (PDE) activity. H2S replacing isobutylmethylxanthine in the differentiation program induced adipocyte differentiation in part. Inhibiting PDE activity by H2S induced peroxisome proliferator activated receptor γ (PPARγ) protein and mRNA expression. Of note, H2S directly sulfhydrated PPARγ protein. Sulfhydrated PPARγ increased its nuclear accumulation, DNA binding activity and adipogenesis gene expression, thereby increasing glucose uptake and lipid storage, which were blocked by the desulfhydration reagent DTT. H2S induced PPARγ sulfhydration, which was blocked by mutation of the C139 site of PPARγ. In mice fed a high-fat diet (HFD) for 4 weeks, the CSE inhibitor decreased but H2S donor increased adipocyte numbers. In obese mice fed an HFD for 13 weeks, H2S treatment increased PPARγ sulfhydration in adipose tissues and attenuated insulin resistance but did not increase obesity. In conclusion, CSE-H2S increased PPARγ activity by direct sulfhydration at the C139 site, thereby changing glucose into triglyceride storage in adipocytes. CSE-H2S-mediated PPARγ activation might be a new therapeutic target for diabetes associated with obesity.

  15. Saturable binding of /sup 35/S-t-butylbicyclophosphorothionate to the sites linked to the GABA receptor and the interaction with gabaergic agents

    SciTech Connect

    Wong, D.T.; Threlkeld, P.G.; Bymaster, F.P.; Squires, R.F.

    1984-02-27

    /sup 35/-S-t-Butylbicyclophosphorothionate (/sup 35/S-TBPS) binds in a concentration-saturable manner to specific sites on membranes from rat cerebral cortex. Using a filtration assay at 25/sup 0/C, in 250 mM NaCl, specific binding of /sup 35/S-TBPS constitutes about 84 to 94 percent of total binding, depending on radioligand concentrations. /sup 35/S-TBPS binding is optimal in the presence of NaCl or NaBr and substantially less in the presence of NaI or NaF. It is sensitive to the treatment with 0.05 percent Triton X-100 but not to repeated freezing and thawing, procedures which increase /sup 3/H-GABA binding. Pharmacological studies show that /sup 35/S-TBPS binding is strongly inhibited by GABA-A receptor agonists (e.g., GABA and muscimol) and by the noncompetitive antagonist, picrotoxin, but not the competitive antagonist, bicuculline. Compounds which enhance binding of radioactive GABA and benzodiazepines, such as the pyrazolopyridines, cartazolate and trazolate, and a diaryl-triazine, LY81067, are also potent inhibitors of /sup 35/S-TBPS binding, with LY81067 being the most effective. The effects of GABA, picrotoxin

  16. Further studies on conformationally constrained tricyclic tropane analogues and their uptake inhibition at monoamine transporter sites: synthesis of (Z)-9-(substituted arylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes as a novel class of serotonin transporter inhibitors.

    PubMed

    Zhang, Ao; Zhou, Guochun; Hoepping, Alexander; Mukhopadhyaya, Jayanta; Johnson, Kenneth M; Zhang, Mei; Kozikowski, Alan P

    2002-04-25

    A novel series of conformationally constrained tricyclic tropane analogues, (Z)-9-(substituted arylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes, were prepared, and their abilities to inhibit high-affinity uptake of dopamine (DA), serotonin (5-HT), and norepinephrine (NE) into rat brain nerve endings (synaptosomes) were evaluated. First, a systematic screening of a variety of different substituents on the phenyl ring indicated that the substitution pattern plays an important role in the monoamine transporter activity. Most compounds in this series possessed a very low activity at the DA transporter (DAT) but a good to excellent affinity for the 5-HT transporter (SERT). In the case of para-substituted phenyl analogues, the electronic character of the substituent did not affect uptake inhibition as dramatically as observed in some benztropine analogues. Among these compounds, the 4-bromophenyl and 4-isopropylphenyl analogues 8d and 8j exhibited the highest potency at the SERT with a K(i) value of 10 nM. In the 3,4-disubstituted phenyl series, even more potent and highly selective compounds were discovered. Compound 8o has a K(i) value of 2.3 nM for uptake inhibition at the SERT, a DAT/SERT uptake ratio of 2360, and a NET/SERT uptake ratio of 200. Compound 8p exhibited a K(i) value of 1.8 nM for uptake inhibition at the SERT, a DAT/SERT uptake ratio of 1740, and a NET/SERT uptake ratio of 151. These compounds are 3-4-fold more potent than the antidepressant medication fluoxetine, and the selectivities for SERT over DAT and NET are also better than those of fluoxetine. Second, a variety of functional modifications on the ester moiety were investigated. Substitution by other esters or amides as well as alkenes did not increase potency, while most of the acetates or benzoates (16-21, 23, and 24) and the ketone 28 exhibited significantly improved activity. A good hydrogen-bonding ability of the substituent is believed to be required for high activity. The most potent and

  17. Mitochondrial calcium uptake.

    PubMed

    Williams, George S B; Boyman, Liron; Chikando, Aristide C; Khairallah, Ramzi J; Lederer, W J

    2013-06-25

    Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.

  18. Saturable binding of /sup 35/S-t-butylbicyclophosphorothionate to the sites linked to the GABA receptor and the interaction with gabaergic agents

    SciTech Connect

    Wong, D.T.; Threlkeld, P.G.; Bymaster, F.P.; Squires, R.F.

    1984-02-27

    /sup 35/S-t-Butylbicyclophosphorothionate (/sup 35/S-TBPS) binds in a concentration-saturable manner to specific sites on membranes from rat cerebral cortex. Using a filtration assay at 25/sup 0/C, in 250 mM NaCl, specific binding of /sup 35/S-TBPS constitutes about 84 to 94 percent of total binding, depending on radioligand concentrations. /sup 35/S-TBPS binding is optimal in the presence of NaCl or NaBr and substantially less in the presence of NaI or NaF. It is sensitive to the treatment with 0.05 percent Triton X-100 but not to repeated freezing and thawing, procedures which increase /sup 3/H-GABA binding. Pharmacological studies show that /sup 35/S-TBPS binding is strongly inhibited by GABA-A receptor agonists (e.g., GABA and muscimol) and by the noncompetitive antagonist, picrotoxin, but not the competitive antagonist, bicuculline. Compounds which enhance binding of radioactive GABA and benzodiazepines, such as the pyrazolopyridines, cartazolate and tracazolate, and a diaryltriazine, LY81067, are also potent inhibitors of /sup 35/S-TBPS binding, with LY81067 being the most effective. The effects of GABA, picrotoxin and LY81067 on the saturable binding of /sup 35/S-TBPS in cortical membranes are compared. The present findings are consistent with the interpretation that /sup 35/S-TBPS bind at or near the picrotoxin-sensitive anion recognition sites of the GABA/benzodiazepine/picrotoxin receptor complex.

  19. Proton uptake associated with the reduction of the primary quinone Q(A) influences the binding site of the secondary quinone Q(B) in Rhodopseudomonas viridis photosynthetic reaction centers.

    PubMed

    Zachariae, U; Lancaster, C R

    2001-06-01

    Previously, two binding sites for the secondary quinone Q(B) in the photosynthetic reaction center (RC) from Rhodopseudomonas viridis were identified by X-ray crystallography, a 'proximal' binding site close to the non-heme iron, and a 'distal' site, displaced by 4.2 A along the path of the isoprenoid tail [C.R.D. Lancaster and H. Michel, Structure 5 (1997) 1339-1359]. The quinone ring planes in the two sites differ by roughly a 180 degrees rotation around the isoprenoid tail. Here we present molecular dynamics simulations, which support the theory of a spontaneous transfer of Q(B) between the distal site and the proximal site. In contrast to earlier computational studies on RCs, the molecular dynamics simulations of Q(B) migration resulted in a proximal Q(B) binding pattern identical to that of the crystallographic findings. Also, we demonstrate that the preference towards the proximal Q(B) location is not necessarily attributed to reduction of Q(B) to the semiquinone, but already to the preceding reduction of the primary quinone Q(A) and resulting protonation changes in the protein. Energy mapping of the Q(B) binding pocket indicates that the quinone ring rotation required for completion of the transfer between the two sites is improbable at the distal or proximal binding sites due to high potential barriers, but may be possible at a newly identified position near the distal binding site.

  20. Putrescine uptake in saintpaulia petals.

    PubMed

    Bagni, N; Pistocchi, R

    1985-02-01

    Putrescine uptake and the kinetics of this uptake were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments of [(3)H] or [(14)C] putrescine were done on single petals at room temperature at various pH values. The results show that putrescine uptake occurs against a concentration gradient at low external putrescine concentration (0.5-100 micromolar) and follows a concentration gradient at higher external putrescine concentrations (100 micromolar to 100 millimolar). 2,4-Dinitrophenol and carbonylcyanide-m-chlorophenylhydrazone, two uncouplers, had no effect on putrescine uptake. Uptake rates were constant for 2 hours, reaching a maximum after 3 to 4 hours. Putrescine uptake depended markedly on the external pH and two maxima were observed: at low external concentrations of putrescine, the optimum was at pH 5 to 5.5; at higher concentrations the optimum was at pH 8. PMID:16664065

  1. Coupling nutrient uptake and energy flow in headwater streams

    SciTech Connect

    Mulholland, Patrick J; Fellows, Christine; Valett, H. Maurice; Dahm, Cliff; Thomas, Steve

    2006-08-01

    Nutrient cycling and energy flow in ecosystems are tightly linked through the metabolic processes of organisms. Greater uptake of inorganic nutrients is expected to be associated with higher rates of metabolism [gross primary production (GPP) and respiration (R)], due to assimilatory demand of both autotrophs and heterotrophs. However, relationships between uptake and metabolism should vary with the relative contribution of autochthonous and allochthonous sources of organic matter. To investigate the relationship between metabolism and nutrient uptake, we used whole-stream and benthic chamber methods to measure rates of nitrate-nitrogen (NO{sub 3}-N) uptake and metabolism in four headwater streams chosen to span a range of light availability and therefore differing rates of GPP and contributions of autochthonous carbon. We coupled whole-stream metabolism with measures of NO{sub 3}-N uptake conducted repeatedly over the same stream reach during both day and night, as well as incubating benthic sediments under both light and dark conditions. NO{sub 3}-N uptake was generally greater in daylight compared to dark conditions, and although day-night differences in whole-stream uptake were not significant, light-dark differences in benthic chambers were significant at three of the four sites. Estimates of N demand indicated that assimilation by photoautotrophs could account for the majority of NO{sub 3}-N uptake at the two sites with relatively open canopies. Contrary to expectations, photoautotrophs contributed substantially to NO{sub 3}-N uptake even at the two closed-canopy sites, which had low values of GPP/R and relied heavily on allochthonous carbon to fuel R.

  2. Endocytotic uptake of nutrients in carnivorous plants.

    PubMed

    Adlassnig, Wolfram; Koller-Peroutka, Marianne; Bauer, Sonja; Koshkin, Edith; Lendl, Thomas; Lichtscheidl, Irene K

    2012-07-01

    Carnivorous plants trap, digest and absorb animals in order to supplement their mineral nutrition. Nutrients absorbed by the plant include different nitrogen species, phosphate, potassium, trace elements and small organic compounds. Uptake is usually thought to be performed via specific channels, but this study provides evidence that endocytosis is involved as well. Traps of the carnivorous plants Nepenthes coccinea, Nepenthes ventrata, Cephalotus follicularis, Drosophyllum lusitanicum, Drosera capensis, Dionaea muscipula, Aldrovanda vesiculosa, Genlisea violacea × lobata, Sarracenia psittacina and Sarracenia purpurea were stained with methylene blue in order to identify possible sites of uptake. The permeable parts of the traps were incubated with fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA) and other fluorescent endocytosis markers, combined with the soluble protein BSA or respiratory inhibitors. Uptake was studied by confocal microscopy. In Nepenthes, small fluorescent vesicles became visible 1 h after incubation with FITC-BSA. These vesicles fused to larger compartments within 30 h. A similar behaviour was found in the related genera Drosera, Dionaea, Aldrovanda and Drosophyllum but also in Cephalotus with glands of different evolutionary origin. In Genlisea and Sarracenia, no evidence for endocytosis was found. We propose that in many carnivorous plants, nutrient uptake by carriers is supplemented by endocytosis, which enables absorption and intracellular digestion of whole proteins. The advantage for the plant of reducing secretion of enzymes for extracellular digestion is evident.

  3. Endocytotic uptake of nutrients in carnivorous plants.

    PubMed

    Adlassnig, Wolfram; Koller-Peroutka, Marianne; Bauer, Sonja; Koshkin, Edith; Lendl, Thomas; Lichtscheidl, Irene K

    2012-07-01

    Carnivorous plants trap, digest and absorb animals in order to supplement their mineral nutrition. Nutrients absorbed by the plant include different nitrogen species, phosphate, potassium, trace elements and small organic compounds. Uptake is usually thought to be performed via specific channels, but this study provides evidence that endocytosis is involved as well. Traps of the carnivorous plants Nepenthes coccinea, Nepenthes ventrata, Cephalotus follicularis, Drosophyllum lusitanicum, Drosera capensis, Dionaea muscipula, Aldrovanda vesiculosa, Genlisea violacea × lobata, Sarracenia psittacina and Sarracenia purpurea were stained with methylene blue in order to identify possible sites of uptake. The permeable parts of the traps were incubated with fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA) and other fluorescent endocytosis markers, combined with the soluble protein BSA or respiratory inhibitors. Uptake was studied by confocal microscopy. In Nepenthes, small fluorescent vesicles became visible 1 h after incubation with FITC-BSA. These vesicles fused to larger compartments within 30 h. A similar behaviour was found in the related genera Drosera, Dionaea, Aldrovanda and Drosophyllum but also in Cephalotus with glands of different evolutionary origin. In Genlisea and Sarracenia, no evidence for endocytosis was found. We propose that in many carnivorous plants, nutrient uptake by carriers is supplemented by endocytosis, which enables absorption and intracellular digestion of whole proteins. The advantage for the plant of reducing secretion of enzymes for extracellular digestion is evident. PMID:22417315

  4. Phospholipase A2 and 3H-hemicholinium-3 binding sites in rat brain: A potential second-messenger role for fatty acids in the regulation of high-affinity choline uptake

    SciTech Connect

    Saltarelli, M.D.; Yamada, K.; Coyle, J.T. )

    1990-01-01

    The involvement of phospholipase A2 (PLA2) and fatty acid release in the regulation of sodium-dependent high-affinity choline uptake in rat brain was assessed in vitro through the use of the specific binding of 3H-hemicholinium-3 (3H-HCh-3). Addition of arachidonic acid and other unsaturated fatty acids to rat striatal membranes in vitro resulted in a dose-dependent, temperature-independent activation of 3H-HCh-3 binding. Scatchard analysis revealed that these changes in binding result from a 2-fold increase in the affinity and capacity of 3H-HCh-3 binding. Saturated fatty acids, lysophospholipids, and phospholipids did not affect specific 3H-HCh-3 binding. Addition of defatted BSA to membranes, which had been treated previously with arachidonic acid, completely reversed the increase in specific 3H-HCh-3 binding. However, several inhibitors of fatty acid metabolism, including nordihydroguaiaretic acid, indomethacin, catalase, and superoxide dismutase, did not alter arachidonic acid-induced changes in 3H-HCh-3 binding, suggesting that unsaturated fatty acids, and not their metabolites, are directly responsible for the observed activation of specific 3H-HCh-3 binding. Additionally, unsaturated fatty acids dose-dependently inhibited high-affinity 3H-choline uptake in rat striatal synaptosomes, apparently due to the disruption of synaptosomal integrity. The phospholipase A2 inhibitors quinacrine hydrochloride, trifluoperazine, and 4-bromophenacylbromide dose-dependently inhibited potassium depolarization-induced activation of specific 3H-HCh-3 binding in slices of rat brain in vitro. Similarly, both quinacrine and trifluoperazine inhibited the metabolism of phospholipids and the release of fatty acids evoked by either elevated KCl or calcium ionophore A23187.

  5. Recombinant glucose uptake system

    DOEpatents

    Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

    1997-01-01

    Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

  6. Numerical model for the uptake of groundwater contaminants by phreatophytes

    USGS Publications Warehouse

    Widdowson, M.A.; El-Sayed, A.; Landmeyer, J.E.

    2008-01-01

    Conventional solute transport models do not adequately account for the effects of phreatophytic plant systems on contaminant concentrations in shallow groundwater systems. A numerical model was developed and tested to simulate threedimensional reactive solute transport in a heterogeneous porous medium. Advective-dispersive transport is coupled to biodegradation, sorption, and plantbased attenuation processes including plant uptake and sorption by plant roots. The latter effects are a function of the physical-chemical properties of the individual solutes and plant species. Models for plant uptake were tested and evaluated using the experimental data collected at a field site comprised of hybrid poplar trees. A non-linear equilibrium isotherm model best represented site conditions.

  7. Uptake of VOC by sunflower

    NASA Astrophysics Data System (ADS)

    Folkers, A.; Miebach, M.; Kleist, E.; Wildt, J.

    2003-04-01

    To study potential VOC uptake by plants we exposed sunflower (Helianthus annuus) to different VOC in continuously stirred tank reactors. For many VOC like methanol, ethanol, acetone, methylvinylketone, isoprene or limonene no uptake was detectable within the accuracy of our analytic set up. Other VOC like hexanal, octanal, (E)-3-hexenol and nopinone were taken up by sunflower. The uptake was related to stomatal aperture. Obviously, these VOC enter the plants through stomata. In case of hexanal, octanal, and (E)-3-hexenol the uptake was only limited by stomatal aperture implying that these VOC are rapidly metabolised. For nopinone the uptake seems to be limited by a slow metabolization. Estimations of deposition velocities showed that dry deposition of these compounds cannot be neglected as sink if diffusion through stomata is the limiting step for dry deposition. In such cases the lifetime with respect to dry deposiotion is comparable to the lifetime with respect to oxidation by hydroxyl radicals.

  8. Stimulation-dependent myocardial calcium uptake into slowly exchangeable compartments

    SciTech Connect

    Fintel, M.; Langer, G.A.

    1986-03-01

    Myocardial calcium uptake into slowly exchangeable sites was increased in response to beating following a period of prolonged quiescence (> 1 hr). Net calcium uptake was measured in rabbit interventricular septa using the /sup 45/Ca washout technique. The maximal increment of slowly exchangeable calcium induced by beating was 20 +/- 2% of calcium uptake during quiescence. The increment in calcium uptake induced by 282 beats in 10 minutes did not differ from the increment induced by 60 beats but was significantly greater than the increment induced by 35 and 15 beats. The total number of beats rather than the frequency of stimulation appeared to be the most critical factor which determined the increment in calcium uptake. Based on the increment of 0.12 +/- 0.02 mmoles/kg dry weight obtained when 15 beats occurred in 10 minutes, the minimum amount of calcium which entered slowly exchangeable sites per beat was calculated to be 1 ..mu..mol/kg wet weight. The increment in slowly exchangeable calcium induced by beating was not affected by ryanodine but was inhibited by the metabolic inhibitor CCCP. In conclusion, a net increment in slowly exchangeable calcium occurs when beating is resumed following a period of prolonged quiescence. This suggests that calcium influx exceeds efflux transiently, under these conditions, and that slowly exchangeable sites represent an important mechanism by which a fraction of incoming calcium is buffered.

  9. Light dependence of selenium uptake by phytoplankton and implications for predicting selenium incorporation into food webs

    USGS Publications Warehouse

    Baines, S.B.; Fisher, N.S.; Doblin, M.A.; Cutter, G.A.; Cutter, L.S.; Cole, B.

    2004-01-01

    The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) and C by intact plankton communities at two sites in the Sacramento/San Joaquin River Delta. Our goals were to determine (1) whether C and Se(IV) uptake were coupled, (2) the role of bacteria in Se(IV) uptake, and (3) the Se:C uptake ratio of newly produced organic material. Se(IV) uptake, like C uptake, was strongly related to irradiance. The shapes of both relationships were very similar except that at least 42-56% of Se(IV) uptake occurred in the dark, whereas C uptake in the dark was negligible. Of this dark Se(IV) uptake, 34-67% occurred in the 0.2-1.0-??m size fraction, indicating significant uptake by bacteria. In addition to dark uptake, total Se(IV) uptake consisted of a light-driven component that was in fixed proportion to C uptake. Our estimates of daily areal Se(IV):C uptake ratios agreed very well with particulate Se:C measured at a site dominated by phytoplankton biomass. Estimates of bacterial Se:C were 2.4-13 times higher than for the phytoplankton, suggesting that bacteriovores may be exposed to higher dietary Se concentrations than herbivores.

  10. Manganese uptake of imprinted polymers

    SciTech Connect

    Susanna Ventura

    2015-09-30

    Batch tests of manganese imprinted polymers of variable composition to assess their ability to extract lithium and manganese from synthetic brines at T=45C . Data on manganese uptake for two consecutive cycles are included.

  11. The Helicobacter pylori HpyAXII restriction–modification system limits exogenous DNA uptake by targeting GTAC sites but shows asymmetric conservation of the DNA methyltransferase and restriction endonuclease components

    PubMed Central

    Humbert, Olivier; Salama, Nina R.

    2008-01-01

    The naturally competent organism Helicobacter pylori encodes a large number of restriction–modification (R–M) systems that consist of a restriction endonuclease and a DNA methyltransferase. R–M systems are not only believed to limit DNA exchange among bacteria but may also have other cellular functions. We report a previously uncharacterized H. pylori type II R–M system, M.HpyAXII/R.HpyAXII. We show that this system targets GTAC sites, which are rare in the H. pylori chromosome but numerous in ribosomal RNA genes. As predicted, this type II R–M system showed attributes of a selfish element. Deletion of the methyltransferase M.HpyAXII is lethal when associated with an active endonuclease R.HpyAXII unless compensated by adaptive mutation or gene amplification. R.HpyAXII effectively restricted both unmethylated plasmid and chromosomal DNA during natural transformation and was predicted to belong to the novel ‘half pipe’ structural family of endonucleases. Analysis of a panel of clinical isolates revealed that R.HpyAXII was functional in a small number of H. pylori strains (18.9%, n = 37), whereas the activity of M.HpyAXII was highly conserved (92%, n = 50), suggesting that GTAC methylation confers a selective advantage to H. pylori. However, M.HpyAXII activity did not enhance H. pylori fitness during stomach colonization of a mouse infection model. PMID:18978016

  12. Characterization of cadmium uptake by the water lily Nymphaea aurora.

    PubMed

    Schor-Fumbarov, Tamar; Keilin, Zvika; Tel-Or, Elisha

    2003-01-01

    This study characterizes cadmium (Cd) uptake by the waterlily Nymphaea aurora, (Nymphaeaceae) in two systems: a model hydroponic Cd solution and heavily polluted sludge from two sites in Israel. The uptake of Cd from hydroponic solution resulted in Cd storage in petioles and laminae of Nymphaea, as well as in the roots. The pH of the solution affected Cd solubility and availability, with pH 5.5 yielding maximum Cd content in the plant (140 mg Cd per g DW). Cd uptake was reduced by the addition of EDTA to the hydroponic growth medium, although EDTA enhanced heavy metal uptake by terrestrial plants. Nymphaea efficiently reduced the concentration of Cd in heavy metal polluted urban and industrial sludge and the amount of Cd uptake was enhanced by the addition of KCl to the sludge and by adjustment of the pH to 5.5. The inherent growth patterns of Nymphaea plants allowed Cd uptake by the shoot and root, and resulted in maximum contact between the various plant parts and the growth media. Thus, Nymphaea has potential as an optimal, highly effective phytoremediation tool for the removal of Cd from polluted waste sources.

  13. Uptake of inert microparticles in normal and immune deficient mice.

    PubMed

    Smyth, S H; Feldhaus, S; Schumacher, U; Carr, K E

    2008-01-01

    Intestinal microparticle uptake is important for drug delivery, environmental pollution and multiple organ dysfunction syndrome. This paper explores further whether uptake occurs at mucosa associated lymphoid tissue (MALT) via the microfold (M) cells of Peyer's patch domes or through villous epithelium. It does this by comparing the results of exposure of either severe combined immunodeficient (SCID) mice (lacking MALT) or normal BALBc mice, to oral gavage with 2 microm fluorescent latex microparticles. At 5 and 30 min after gavage, full circumference samples along the small intestine were processed for fluorescence microscopy and microparticle numbers were collected for surface and tissue sites. Uptake occurred in both BALBc and SCID mice within 5 min of particle administration and increased further in the following 25 min. In BALBc mice, almost all particles (96%) are in non-MALT sites in MALT circumference samples, with very few at the domes: uptake was also substantial in entirely villous samples. In SCID mice, particle numbers were only slightly lower than those of the BALBc mice, and occurred exclusively by the villous route. These findings confirm that the villous uptake route must be considered when assessing the extent of the dose delivered following pharmaceutical or toxicological oral exposure to microparticles. PMID:17723283

  14. Uptake of antibiotics by human polymorphonuclear leukocyte cytoplasts

    SciTech Connect

    Hand, W.L.; King-Thompson, N.L. , Decatur, GA )

    1990-06-01

    Enucleated human polymorphonuclear leukocytes (PMN cytoplasts), which have no nuclei and only a few granules, retain many of the functions of intact neutrophils. To better define the mechanisms and intracellular sites of antimicrobial agent accumulation in human neutrophils, we studied the antibiotic uptake process in PMN cytoplasts. Entry of eight radiolabeled antibiotics into PMN cytoplasts was determined by means of a velocity gradient centrifugation technique. Uptakes of these antibiotics by cytoplasts were compared with our findings in intact PMN. Penicillin entered both intact PMN and cytoplasts poorly. Metronidazole achieved a concentration in cytoplasts (and PMN) equal to or somewhat less than the extracellular concentration. Chloramphenicol, a lipid-soluble drug, and trimethoprim were concentrated three- to fourfold by cytoplasts. An unusual finding was that trimethroprim, unlike other tested antibiotics, was accumulated by cytoplasts more readily at 25 degrees C than at 37 degrees C. After an initial rapid association with cytoplasts, cell-associated imipenem declined progressively with time. Clindamycin and two macrolide antibiotics (roxithromycin, erythromycin) were concentrated 7- to 14-fold by cytoplasts. This indicates that cytoplasmic granules are not essential for accumulation of these drugs. Adenosine inhibited cytoplast uptake of clindamycin, which enters intact phagocytic cells by the membrane nucleoside transport system. Roxithromycin uptake by cytoplasts was inhibited by phagocytosis, which may reduce the number of cell membrane sites available for the transport of macrolides. These studies have added to our understanding of uptake mechanisms for antibiotics which are highly concentrated in phagocytes.

  15. Brain uptake of ketoprofen-lysine prodrug in rats.

    PubMed

    Gynther, Mikko; Jalkanen, Aaro; Lehtonen, Marko; Forsberg, Markus; Laine, Krista; Ropponen, Jarmo; Leppänen, Jukka; Knuuti, Johanna; Rautio, Jarkko

    2010-10-31

    The blood-brain barrier (BBB) controls the entry of xenobiotics into the brain. Often the development of central nervous system drugs needs to be terminated because of their poor brain uptake. We describe a way to achieve large neutral amino acid transporter (LAT1)-mediated drug transport into the rat brain. We conjugated ketoprofen to an amino acid l-lysine so that the prodrug could access LAT1. The LAT1-mediated brain uptake of the prodrug was demonstrated with in situ rat brain perfusion technique. The ability of the prodrug to deliver ketoprofen into the site of action, the brain intracellular fluid, was determined combining in vivo and in vitro experiments. A rapid brain uptake from blood and cell uptake was seen both in in situ and in vivo experiments. Therefore, our results show that a prodrug approach can achieve uptake of drugs via LAT1 into the brain intracellular fluid. The distribution of the prodrug in the brain parenchyma and the site of parent drug release in the brain were shown with in vivo and in vitro studies. In addition, our results show that although lysine or ketoprofen are not LAT1-substrates themselves, by combining these molecules, the formed prodrug has affinity for LAT1. PMID:20727958

  16. Post-uptake metabolism affects quantification of amino acid uptake.

    PubMed

    Warren, Charles R

    2012-01-01

    • The quantitative significance of amino acids to plant nutrition remains controversial. This experiment determined whether post-uptake metabolism and root to shoot export differ between glycine and glutamine, and examined implications for estimation of amino acid uptake. • Field soil containing a Eucalyptus pauciflora seedling was injected with uniformly (13)C- and (15)N-labelled glycine or glutamine. I quantified (15)N and (13)C excess in leaves and roots and intact labelled amino acids in leaves, roots and stem xylem sap. A tunable diode laser quantified fluxes of (12)CO(2) and (13)CO(2) from leaves and soil. • 60-360 min after addition of amino acid, intact molecules of U-(13)C,(15)N glutamine were < 5% of (15)N excess in roots, whereas U-(13)C,(15)N glycine was 30-100% of (15)N excess in roots. Intact molecules of glutamine, but not glycine, were exported from roots to shoots. • Post-uptake metabolism and transport complicate interpretation of isotope labelling such that root and shoot contents of intact amino acid, (13)C and (15)N may not reflect rates of uptake. Future experiments should focus on reconciling discrepancies between intact amino acid, (13)C and (15)N by determining the turnover of amino acids within roots. Alternatively, post-uptake metabolism and transport could be minimized by harvesting plants within minutes of isotope addition.

  17. The MDP skull uptake test: A new diagnostic tool

    SciTech Connect

    Ell, P.J.; Jarritt, P.H.; Cullum, I.; Lui, D.

    1984-01-01

    An original approach to the measurement of bone turnover is presented. With SPECT, the authors have measured in pgr/ml, the uptake of MDP by the skull in man. The Cleon 710 scanner, ring phantoms and bone biopsies were used for ultimate in vivo/in vitro count recovery correlation and calibration. A normal range for 24 patients was found: 8.5 to 19.5 pgr/ml with a mean of 14. For patients with bony metastases (12), the values were: 22.5 to 50, mean of 30. For 5 patients with osteomalacia, the values were 46 to 68, mean of 62: for 12 patients with hyperparathyroidism, the values were 37 to 48.5, mean of 43. In 3 patients with Pagets disease, the values were 58.5 to 75, with a mean of 65. In 76 patients with metastatic disease to bone, the conventional wholebody bone scan was investigated against the following: 24h wholebody retention of MDP (WBR), skull uptake as described and GFR by Cr-51-DTPA. There is a correlation between GFR and WBR - r=0.67. There is a lesser correlation between GFR and skull uptake - r=0.3. There is no correlation between skull uptake and WBR - r=0.1. The comparison of skull uptake data with normal whole body bone scans leads to a significant proportion of cancer patients with positive skull uptake data. Monostotic disease (especially if metabolic in nature) expresses itself by abnormal skull uptake even if the clinical site of abnormality lies outside the skull. This new technique is ideal as a tool to investigate phosphonate concentration in bone. With it, the authors have shown the effect of specific activity of label on skull uptake, which increases as the specific activity of labelled MDP decreases.

  18. Nitrogen Uptake in Spinach

    NASA Astrophysics Data System (ADS)

    Ramirez, J.; VanBenthem, P.

    2013-12-01

    A plant's absorption of nitrogen can be encouraged by a variety of environmental factors, especially the application of fertilizers. As a common limiting factor in plant growth, not up taking enough nitrogen can be a result of an unhealthy plant. Moreover, as farmers seek out methods to increase growth of plants, fertilizers are used as a solution to the issue of nitrogen deficiency to incorporate additional nitrogen from chemical or organic sources, by not using the right fertilizer can greatly affect the plats. The point of this research project is to determine the effect of various fertilizers on the plant growth, and to correlate the measured nitrogen, water and chlorophyll content in spinach leaves. Spinach leaves were used because they are known to quickly uptake chemicals in the environment. The spinach plants were exposed to four different growing parameters, which are referred to as control, ammonium nitrate, MiracleGro , and organic. The spinach was originally placed in nitrogen deficient soil with only 2.2x10 4 weight percent (wt. %) nitrogen. The leaves in the control group were grown in this nitrogen deficient soil without any fertilizer added. Ammomium nitrate and MiracleGro were added to the spinach in the A and MG groups, respectively, and organic chicken stool was used for the O group. By using a spectral imaging system and flame combustion techniques, the chlorophyll content can be related to the nitrogen content in the spinach leaves. In these spinach leaves, nitrogen and chlorophyll content were measured, chlorophyll is a green pigment that plays a crucial role in producing nutrients for green plants. The lack of chlorophyll will allow the plant to become susceptible to diseases, so it is extremely important that the plants have a high content of chlorophyll. The role of nitrogen in chlorophyll is very important and helps in the creation of chlorophyll; therefore it is necessary that an appropriate amount of nitrogen is added for optimal growth

  19. Mechanisms of Ocean Heat Uptake

    NASA Astrophysics Data System (ADS)

    Garuba, Oluwayemi

    An important parameter for the climate response to increased greenhouse gases or other radiative forcing is the speed at which heat anomalies propagate downward in the ocean. Ocean heat uptake occurs through passive advection/diffusion of surface heat anomalies and through the redistribution of existing temperature gradients due to circulation changes. Atlantic meridional overturning circulation (AMOC) weakens in a warming climate and this should slow the downward heat advection (compared to a case in which the circulation is unchanged). However, weakening AMOC also causes a deep warming through the redistributive effect, thus increasing the downward rate of heat propagation compared to unchanging circulation. Total heat uptake depends on the combined effect of these two mechanisms. Passive tracers in a perturbed CO2 quadrupling experiments are used to investigate the effect of passive advection and redistribution of temperature anomalies. A new passive tracer formulation is used to separate ocean heat uptake into contributions due to redistribution and passive advection-diffusion of surface heating during an ocean model experiment with abrupt increase in surface temperature. The spatial pattern and mechanisms of each component are examined. With further experiments, the effects of surface wind, salinity and temperature changes in changing circulation and the resulting effect on redistribution in the individual basins are isolated. Analysis of the passive advection and propagation path of the tracer show that the Southern ocean dominates heat uptake, largely through vertical and horizontal diffusion. Vertical diffusion transports the tracer across isopycnals down to about 1000m in 100 years in the Southern ocean. Advection is more important in the subtropical cells and in the Atlantic high latitudes, both with a short time scale of about 20 years. The shallow subtropical cells transport the tracer down to about 500m along isopycnal surfaces, below this vertical

  20. Through form to function: root hair development and nutrient uptake

    NASA Technical Reports Server (NTRS)

    Gilroy, S.; Jones, D. L.

    2000-01-01

    Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

  1. Presenilin Promotes Dietary Copper Uptake

    PubMed Central

    Southon, Adam; Greenough, Mark A.; Ganio, George; Bush, Ashley I.; Burke, Richard; Camakaris, James

    2013-01-01

    Dietary copper is essential for multicellular organisms. Copper is redox active and required as a cofactor for enzymes such as the antioxidant Superoxide Dismutase 1 (SOD1). Copper dyshomeostasis has been implicated in Alzheimer’s disease. Mutations in the presenilin genes encoding PS1 and PS2 are major causes of early-onset familial Alzheimer’s disease. PS1 and PS2 are required for efficient copper uptake in mammalian systems. Here we demonstrate a conserved role for presenilin in dietary copper uptake in the fly Drosophila melanogaster. Ubiquitous RNA interference-mediated knockdown of the single Drosophila presenilin (PSN) gene is lethal. However, PSN knockdown in the midgut produces viable flies. These flies have reduced copper levels and are more tolerant to excess dietary copper. Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake. SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat. These data support presenilin being needed for dietary copper uptake in the gut and so impacting on SOD activity and tolerance to oxidative stress. These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake. PMID:23667524

  2. l-Methionine Placental Uptake

    PubMed Central

    Araújo, João R.; Correia-Branco, Ana; Ramalho, Carla; Gonçalves, Pedro; Pinho, Maria J.; Keating, Elisa

    2013-01-01

    Our aim was to investigate the influence of gestational diabetes mellitus (GDM) and GDM-associated conditions upon the placental uptake of 14C-l-methionine (14C-l-Met). The 14C-l-Met uptake by human trophoblasts (TBs) obtained from normal pregnancies (normal trophoblast [NTB] cells) is mainly system l-type amino acid transporter 1 (LAT1 [L])-mediated, although a small contribution of system y+LAT2 is also present. Comparison of 14C-l-Met uptake by NTB and by human TBs obtained from GDM pregnancies (diabetic trophoblast [DTB] cells) reveals similar kinetics, but a contribution of systems A, LAT2, and b0+ and a greater contribution of system y+LAT1 appears to exist in DTB cells. Short-term exposure to insulin and long-term exposure to high glucose, tumor necrosis factor-α, and leptin decrease 14C-l-Met uptake in a human TB (Bewo) cell line. The effect of leptin was dependent upon phosphoinositide 3-kinase, extracellular-signal-regulated kinase 1/2 (ERK/MEK 1/2), and p38 mitogen-activated protein kinase. In conclusion, GDM does not quantitatively alter 14C-l-Met placental uptake, although it changes the nature of transporters involved in that process. PMID:23653387

  3. UPTAKE OF RADIONUCLIDE METALS BY SPME FIBERS

    SciTech Connect

    Duff, M; S Crump, S; Robert02 Ray, R; Keisha Martin, K; Donna Beals, D

    2006-08-28

    The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) and fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of HE and FD residue involves using solid phase microextraction or SPME fibers to remove residue of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most metals. However, no studies have measured the affinity of radionuclides for SPME fibers. The focus of this research was to examine the affinity of dissolved radionuclide ({sup 239/240}Pu, {sup 238}U, {sup 237}Np, {sup 85}Sr, {sup 133}Ba, {sup 137}Cs, {sup 60}Co and {sup 226}Ra) and stable radionuclide surrogate metals (Sr, Co, Ir, Re, Ni, Ba, Cs, Nb, Zr, Ru, and Nd) for SPME fibers at the exposure conditions that favor the uptake of HE and FD residues. Our results from radiochemical and mass spectrometric analyses indicate these metals have little measurable affinity for these SPME fibers during conditions that are conducive to HE and FD residue uptake with subsequent analysis by liquid or gas phase chromatography with mass spectrometric detection.

  4. Comparison of characteristics of dopamine uptake and mazindol binding in mouse striatum.

    PubMed

    Zimányi, I; Lajtha, A; Reith, M E

    1989-12-01

    Biochemical and pharmacological studies suggest that the binding of [3H]mazindol is functionally related to the dopamine uptake carrier complex in rodent striatum. In order to study further the relationship between the substrate recognition site for dopamine uptake and the high-affinity binding site for mazindol the uptake of [3H]dopamine and the binding of [3H]mazindol was studied in BALB/cBy mouse striatum in various buffers (Tris, HEPES, bicarbonate-phosphate). Kinetic analysis showed that the Kd of the binding of [3H]mazindol and the Km of the uptake of [3H]dopamine was changed by different sodium concentrations and/or by the presence of Tris, while the Bmax and the Vmax remained essentially the same. However, the shape of the Na+ dependency curves was not the same for mazindol binding and dopamine uptake in the various buffers. The inhibitory effect of other cations such as K+ and Tris was also different on binding and uptake under similar experimental circumstances. Dopamine did not slow down the dissociation of mazindol from its site and this effect was not sodium-sensitive. These complexities can be accommodated by a model that involves overlapping sites for mazindol and dopamine on the dopamine uptake carrier complex, and translocation-reorientation steps. PMID:2615854

  5. Uptake of atmospheric tritium by market foods

    SciTech Connect

    Inoue, Y.; Tanaka-Miyamoto, K.; Iwakura, T. )

    1992-03-01

    In this paper uptake of tritium by market foods from tritiated water vapor in the air is investigated using cereals and beans purchased in Deep River, Canada. The concentrations of tissue free water tritium (TFWT) and organically bound tritium (OBT) range from 12 to 79% and from 10 to 38% respectively, of that estimated for atmospheric water vapor of the sampling month. The specific activity ratios of OBT to TFWT were constant for cereals, but variable for beans. The elevated OBT was shown to be the result of isotopic exchange of labile hydrogen by the fact that washing the foods with tritium free-water reduced their tritium contents to levels characteristic of their production sites.

  6. Pulmonary uptake of morphine (M)

    SciTech Connect

    Roerig, D.L.; Bunke, S.S.; Kotrly, K.J.; Dawson, C.A.; Kampine, J.P.

    1986-03-01

    Previously the authors reported less than 5% of M was taken up during the first pass through the human lung. The low uptake of this basic lipophilic amine was further investigated in a single pass isolated perfused rat lung (IPL) in comparison to uptake of radiolabelled H/sub 2/O, antipyrine (A), aminopyrine (AM), nicotine (N) and phenylethylamine (P). The IPL was perfused for 5 min with each drug (5nmol/ml) and effluent collected in 10 sec fractions. Pulmonary extraction was calculated using indocyanine green dye as a non-extractable reference indicator. Accumulation of all compounds in the IPL reached an apparent equilibrium within 4 min. At equilibrium lung/perfusate conc. ratios for H/sub 2/O, A, AM, N, P and M were 1.04, 0.84, 0.85, 1.44, 2.57 and 1.13 respectively. The time course of M uptake differed from the other compounds since initial extraction of M was low (23%) compared to 75%, 53%, 35%, 82% and 86% for H/sub 2/O, A, AM, N and P respectively. Also, the half time to equilibrium for M was longer (50 sec) compared to 18, 21, 26, 19 and 22 sec for H/sub 2/O, A, AM, N and P respectively. The low initial pulmonary extraction of M compared to these compounds followed by greater M extraction during the remainder of drug infusion suggests uptake mechanisms for M different than the flow limited uptake for water and other basic amine drugs.

  7. Lithium isotope fractionation during uptake by gibbsite

    NASA Astrophysics Data System (ADS)

    Wimpenny, Josh; Colla, Christopher A.; Yu, Ping; Yin, Qing-Zhu; Rustad, James R.; Casey, William H.

    2015-11-01

    The intercalation of lithium from solution into the six-membered μ2-oxo rings on the basal planes of gibbsite is well-constrained chemically. The product is a lithiated layered-double hydroxide solid that forms via in situ phase change. The reaction has well established kinetics and is associated with a distinct swelling of the gibbsite as counter ions enter the interlayer to balance the charge of lithiation. Lithium reacts to fill a fixed and well identifiable crystallographic site and has no solvation waters. Our lithium-isotope data shows that 6Li is favored during this intercalation and that the solid-solution fractionation depends on temperature, electrolyte concentration and counter ion identity (whether Cl-, NO3- or ClO4-). We find that the amount of isotopic fractionation between solid and solution (ΔLisolid-solution) varies with the amount of lithium taken up into the gibbsite structure, which itself depends upon the extent of conversion and also varies with electrolyte concentration and in the counter ion in the order: ClO4- < NO3- < Cl-. Higher electrolyte concentrations cause more rapid expansion of the gibbsite interlayer and some counter ions, such as Cl-, are more easily taken up than others, probably because they ease diffusion. The relationship between lithium loading and ΔLisolid-solution indicates two stages: (1) uptake into the crystallographic sites that favors light lithium, in parallel with adsorption of solvated cations, and (2) continued uptake of solvated cations after all available octahedral vacancies are filled; this second stage has no isotopic preference. The two-step reaction progress is supported by solid-state NMR spectra that clearly resolve a second reservoir of lithium in addition to the expected layered double-hydroxide phase.

  8. Polyamine Uptake, Kinetics, and Competition among Polyamines and between Polyamines and Inorganic Cations.

    PubMed

    Pistocchi, R; Bagni, N; Creus, J A

    1986-02-01

    Polyamine uptake, the kinetics of this uptake, and the competition among polyamines and between polyamines and inorganic cations were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments using (14)C-labeled polyamines were carried out on single petals, at room temperaure (20 degrees C) and in the light. The results show that putrescine, spermidine, and spermine uptake was dependent on the external pH and occurred up to high external polyamine concentrations with K(m) values of 8.6, 1.2, and 2.1 millimolar, respectively, with spermidine being the most absorbed at low concentration (17 micromolar). Putrescine and spermidine did not seem to compete for the same site of absorption. Furthermore, putrescine and spermidine uptake was not inhibited by Ca(2+), Mg(2+), and K(+) at the same concentrations (17 micromolar), whereas 1.7 millimolar Ca(2+) inhibited and K(+) enhanced spermidine uptake. The intracellular localization of the absorbed putrescine was determined using two different methods. Very little label was found in the apoplast, while most of it was localized in the 98,500g supernatant. According to our data the vacuole, which represents a substantial part of Saintpaulia parenchyma cells, could be a site of putrescine accumulation. 2,4-Dinitrophenol and diethylstilbestrol did not inhibit uptake; however, at 0 degrees C there was a 35% inhibition of spermidine uptake, compared with the controls kept at 20 degrees C as well as a 68% inhibition with 20 millimolar NaSCN. PMID:16664661

  9. Uptake of auxins into membrane vesicles isolated from pea stems: an in vitro auxin transport system

    SciTech Connect

    Slone, J.H.

    1985-01-01

    The objective of this research was to test the applicability of the chemiosmotic theory of auxin transport to a subcellular system. Membrane vesicles were isolated from the basal portion of the third internode of etiolated pea plants (Pisum sativum L. var. Alaska) by differential centrifugation. Uptake of auxin was determined by adding /sup 14/C-labeled indoleacetic acid (IAA) to vesicles. Nigericin, a monovalent cation ionophore, and the electrogenic protonophore, carbonyl-cyanide m-chlorophenylhydrazone (CCCP), at micromolar concentrations abolished saturable uptake. Bursting vesicles by sonication, osmotic shock and freeze/thawing also eliminated saturable uptake. As the temperature increased from 0 to 30/sup 0/C, saturable uptake decreased markedly. Nonsaturable auxin uptake was less affected by these treatments. The pH gradient-dependent uptake of auxin appeared to be a transmembrane uptake of auxin into the vesicles rather than surface binding. Unlabeled IAA, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-naphthaleneacetic acid (NAA) at low concentrations reduced the saturable accumulation of (/sup 14/C)IAA in vesicles, while phenylacetic acid, benzoic acid, and 1-NAA were effective only at high concentrations. Kinetic analysis revealed two types of sites: a high affinity site with an uptake capacity of 25 to 40 pmoles/g tissue, and a low affinity site with an uptake capacity of 260 to 600 pmole/g tissue, fresh wt. In conclusion, several principal elements of an auxin transport system, as specific by the chemiosmotic theory of polar auxin transport, were present in membrane vesicles isolated from relatively mature pea stem tissue. However, one important aspect of the theory was not demonstrated in this in vitro system - a TIBA/NPA-sensitive auxin efflux. The kinetics and specificity of auxin uptake strongly suggested that this system was physiologically significant.

  10. Anorectic activities of serotonin uptake inhibitors: correlation with their potencies at inhibiting serotonin uptake in vivo and /sup 3/H-mazindol binding in vitro

    SciTech Connect

    Angel, I.; Taranger, M.A.; Claustre, Y.; Scatton, B.; Langer, S.Z.

    1988-01-01

    The mechanism of anorectic action of several serotonin uptake inhibitors was investigated by comparing their anorectic potencies with several biochemical and pharmacological properties and in reference to the novel compound SL 81.0385. The anorectic effect of the potent serotonin uptake inhibitor SL 81.0385 was potentiated by pretreatment with 5-hydroxytryptophan and blocked by the serotonin receptor antagonist metergoline. A good correlation was obtained between the ED/sub 50/ values of anorectic action and the ED/sub 50/ values of serotonin uptake inhibition in vivo (but not in vitro) for several specific serotonin uptake inhibitors. Most of the drugs tested displaced (/sup 3/H)-mazindol from its binding to the anorectic recognition site in the hypothalamus, except the pro-drug zimelidine which was inactive. Excluding zimelidine, a good correlation was obtained between the affinities of these drugs for (/sup 3/H)-mazindol binding and their anorectic action indicating that their anorectic activity may be associated with an effect mediated through this site. Taken together these results suggest that the anorectic action of serotonin uptake inhibitors is directly associated to their ability to inhibit serotonin uptake and thus increasing the synaptic levels of serotonin. The interactions of these drugs with the anorectic recognition site labelled with (/sup 3/H)-mazindol is discussed in connection with the serotonergic regulation of carbohydrate intake.

  11. Site Partition: Turning One Site into Two for Adsorbing CO2.

    PubMed

    Tian, Ziqi; Dai, Sheng; Jiang, De-En

    2016-07-01

    We propose the concept of site partition to explain the role of guest molecules in increasing CO2 uptake in metal-organic frameworks and to design new covalent porous materials for CO2 capture. From grand canonical Monte Carlo simulations of CO2 sorption in the recently synthesized CPM-33 MOFs, we show that guest insertion divides one open metal site into two relatively strong binding sites, hence dramatically increasing CO2 uptake. Further, we extend the site partition concept to covalent organic frameworks with large free volume. After insertion of a designed geometry-matching guest, we show that the volumetric uptake of CO2 doubles. Therefore, the concept of site partition can be used to engineer the pore space of nanoporous materials for higher gas uptake. PMID:27320252

  12. Cellular uptake of metallated cobalamins.

    PubMed

    Tran, Mai Thanh Quynh; Stürup, Stefan; Lambert, Ian Henry; Gammelgaard, Bente; Furger, Evelyne; Alberto, Roger

    2016-03-01

    Cellular uptake of vitamin B12-cisplatin conjugates was estimated via detection of their metal constituents (Co, Pt, and Re) by inductively coupled plasma mass spectrometry (ICP-MS). Vitamin B12 (cyano-cob(iii)alamin) and aquo-cob(iii)alamin [Cbl-OH2](+), which differ in the β-axial ligands (CN(-) and H2O, respectively), were included as control samples. The results indicated that B12 derivatives delivered cisplatin to both cellular cytosol and nuclei with an efficiency of one third compared to the uptake of free cisplatin cis-[Pt(II)Cl2(NH3)2]. In addition, uptake of charged B12 derivatives including [Cbl-OH2](+), [{Co}-CN-{cis-PtCl(NH3)2}](+), [{Re}-{Co}-CN-{cis-PtCl(NH3)2}](+), and [{Co}-CN-{trans-Pt(Cyt)(NH3)2}](2+) (Cyt = cytarabin) was high compared to neutral B12, which implied the existence of an additional internalization pathway for charged B12 vitamin analogs. The affinities of the charged B12 derivatives to the B12 transporters HC, IF and TC were similar to that of native vitamin B12. PMID:26739575

  13. Macroscopic modeling of plant water uptake: soil and root resistances

    NASA Astrophysics Data System (ADS)

    Vogel, Tomas; Votrubova, Jana; Dohnal, Michal; Dusek, Jaromir

    2014-05-01

    The macroscopic physically-based plant root water uptake (RWU) model, based on water-potential-gradient formulation (Vogel et al., 2013), was used to simulate the observed soil-plant-atmosphere interactions at a forest site located in a temperate humid climate of central Europe and to gain an improved insight into the mutual interplay of RWU parameters that affects the soil water distribution in the root zone. In the applied RWU model, the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow. The RWU algorithm is implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation. The RWU model is defined by four parameters (root length density distribution, average active root radius, radial root resistance, and the threshold value of the root xylem potential). In addition, soil resistance to water extraction by roots is related to soil hydraulic conductivity function and actual soil water content. The RWU model is capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. The present study focusses on the sensitivity analysis of the combined soil water flow and RWU model responses in respect to variations of RWU model parameters. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154.

  14. Detecting spatio-temporal controls on depth distributions of root water uptake using soil moisture patterns

    NASA Astrophysics Data System (ADS)

    Blume, Theresa; Heidbüchel, Ingo; Simard, Sonia; Güntner, Andreas; Weiler, Markus

    2016-04-01

    Landscape scale soil moisture patterns show a pronounced shift when plants become active during the growing season. Soil moisture patterns are then not only controlled by soils, topography and related abiotic site characteristics as well as site characteristic throughfall patterns but also by root water uptake. In this study root water uptake from different soil depths is estimated based on diurnal fluctuations in soil moisture content and was investigated with a setup of 15 field sites in a forest in northeastern Germany. These sites cover different topographic positions and forest stands. Vegetation types include pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 5 soil moisture and soil temperature profiles, matric potential, piezometers and sapflow sensors as well as standard climate data. The resulting comprehensive data set of depth distributed root water uptake shows differences in overall amounts as well as in uptake depth distributions between different forest stands, but also related to slope position and thus depth to groundwater. Temporal dynamics of signal strength within the profile suggest a locally shifting spatial distribution of root water uptake depending on water availability. The relative contributions of the different depths to overall root water uptake shift as the summer progresses. However, the relationship of these depth resolved uptake rates to overall soil water availability varies considerably between tree species. This unique data set of depth specific contributions to root water uptake down to a depth of 2 m allows a much more detailed analysis of tree response to water availability than the more common transpiration estimates generated by sapflow or eddy flux measurements.

  15. Measurement of Glucose Uptake in Cultured Cells.

    PubMed

    Yamamoto, Norio; Ueda-Wakagi, Manabu; Sato, Takuya; Kawasaki, Kengo; Sawada, Keisuke; Kawabata, Kyuichi; Akagawa, Mitsugu; Ashida, Hitoshi

    2015-12-08

    Facilitative glucose uptake transport systems are ubiquitous in animal cells and are responsible for transporting glucose across cell surface membranes. Evaluation of glucose uptake is crucial in the study of numerous diseases and metabolic disorders such as myocardial ischemia, diabetes mellitus, and cancer. Detailed in this unit are laboratory methods for assessing glucose uptake into mammalian cells. The unit is divided into five sections: (1) a brief overview of glucose uptake assays in cultured cells; (2) a method for measuring glucose uptake using radiolabeled 3-O-methylglucose; (3) a method for measuring glucose uptake using radiolabeled 2-deoxyglucose (2DG); (4) a microplate method for measuring 2DG-uptake using an enzymatic, fluorometric assay; and (5) a microplate-based method using a fluorescent analog of 2DG.

  16. A mechanism for the hydrogen uptake process in zirconium alloys

    NASA Astrophysics Data System (ADS)

    Cox, B.

    1999-01-01

    Hydrogen uptake data for thin Zircaloy-2 specimens in steam at 300-400°C have been analysed to show that there is a decrease in the rate of uptake with respect to the rate of oxidation when the terminal solid solubility (TSS) of hydrogen in the metal is exceeded. In order for TSS to be reached during pre-transition oxidation a very thin 0.125 mm Zircaloy sheet was used. The specimens had been pickled initially removing all Zr 2(Fe/Ni) particles from the initial surfaces, yet the initial hydrogen uptake rates were still much higher than for Zircaloy-4 or a binary Zr/Fe alloy that did not contain phases that dissolve readily during pickling. Cathodic polarisation at room temperature in CuSO 4 solution showed that small cracks or pores formed the cathodic sites in pre-transition oxide films. Some were at pits resulting from the initial dissolution of the Zr 2(Fe/Ni) phase; others were not; none were at the remaining intermetallics in the original surface. These small cracks are thought to provide the ingress routes for hydrogen. A microscopic steam starvation process at the bottoms of these small cracks or pores, leading to the accumulation of hydrogen adjacent to the oxide/metal interface, and causing breakdown of the passive oxide forming at the bottom of the flaw, is thought to provide the mechanism for the hydrogen uptake process during both pre-transition and post-transition oxidation.

  17. DNA Uptake by Transformable Bacteria

    SciTech Connect

    Lacks, Sanford A.

    1999-03-31

    The various processes of DNA uptake by cells can be categorized as: viral DNA entry, conjugation, or transformation. Within each category, a variety of mechanisms have been found. However, considerable similarities occur among the different mechanisms of conjugation and, especially, transformation. All of these natural mechanisms of DNA transfer are quite elaborate and involve multiple protein components, as the case may be, of the virus, the donor cell, and the recipient cell. The mechanisms of viral infection and conjugation will be discussed mainly with respect to their relevance to transformation.

  18. DNA UPTAKE BY TRANSFORMABLE BACTERIA

    SciTech Connect

    LACKS,S.A.

    1999-09-07

    The various processes of DNA uptake by cells can be categorized as: viral DNA entry, conjugation, or transformation. Within each category, a variety of mechanisms have been found. However, considerable similarities occur among the different mechanisms of conjugation and, especially, transformation. All of these natural mechanisms of DNA transfer are quite elaborate and involve multiple protein components, as the case may be, of the virus, the donor cell, and the recipient cell. The mechanisms of viral infection and conjugation will be discussed mainly with respect to their relevance to transformation.

  19. Localization of glycine, GABA and neuropeptide containing neurons in tiger salamander retina

    SciTech Connect

    Yang, C.Y.

    1988-01-01

    Putative glycinergic and GABAergic neurons in the salamander retina were localized by a parallel analysis of high affinity {sup 3}H-glycine uptake and glycine-like immunoreactivity (Gly-IR) and a comparative analysis of high affinity {sup 3}H-GABA uptake, GABA, like immunoreactivity (GABA-IR), and glutamate decarboxylase immunoreactivity (GAD-IR) at the light microscopic level. Good correspondence of labeling of {sup 3}H-glycine uptake and Gly-IR as well as that of {sup 3}H-GABA uptake and GABA-IR were observed. In addition, GAD immunoreactive neurons contained GABA-IR as well. Extensive colocalization of {sup 3}H-glycine uptake and Gly-IR and that of {sup 3}H-GABA uptake, GABA-IR and perhaps GAD-IR were indicated by the similarities in the distribution, morphology and labeling frequency of neurons and lamination in the inner plexiform layer (IPL). However, the Gly-IR and the GABA-IR probes appeared to be more sensitive and can thus be a reliable marker for glycine and GABA containing neurons respectively.

  20. Ocean uptake of carbon dioxide

    SciTech Connect

    Peng, Tsung-Hung; Takahashi, Taro

    1993-06-01

    Factors controlling the capacity of the ocean for taking up anthropogenic C0{sup 2} include carbon chemistry, distribution of alkalinity, pCO{sup 2} and total concentration of dissolved C0{sup 2}, sea-air pCO{sup 2} difference, gas exchange rate across the sea-air interface, biological carbon pump, ocean water circulation and mixing, and dissolution of carbonate in deep sea sediments. A general review of these processes is given and models of ocean-atmosphere system based on our understanding of these regulating processes axe used to estimate the magnitude of C0{sup 2} uptake by the ocean. We conclude that the ocean can absorb up to 35% of the fossil fuel emission. Direct measurements show that 55% Of C0{sup 2} from fossil fuel burning remains in the atmosphere. The remaining 10% is not accounted for by atmospheric increases and ocean uptake. In addition, it is estimated that an amount equivalent to 30% of recent annual fossil fuel emissions is released into the atmosphere as a result of deforestation and farming. To balance global carbon budget, a sizable carbon sink besides the ocean is needed. Storage of carbon in terrestrial biosphere as a result of C0{sup 2} fertilization is a potential candidate for such missing carbon sinks.

  1. Ocean uptake of carbon dioxide

    SciTech Connect

    Peng, Tsung-Hung ); Takahashi, Taro . Lamont-Doherty Earth Observatory)

    1993-01-01

    Factors controlling the capacity of the ocean for taking up anthropogenic C0[sup 2] include carbon chemistry, distribution of alkalinity, pCO[sup 2] and total concentration of dissolved C0[sup 2], sea-air pCO[sup 2] difference, gas exchange rate across the sea-air interface, biological carbon pump, ocean water circulation and mixing, and dissolution of carbonate in deep sea sediments. A general review of these processes is given and models of ocean-atmosphere system based on our understanding of these regulating processes axe used to estimate the magnitude of C0[sup 2] uptake by the ocean. We conclude that the ocean can absorb up to 35% of the fossil fuel emission. Direct measurements show that 55% Of C0[sup 2] from fossil fuel burning remains in the atmosphere. The remaining 10% is not accounted for by atmospheric increases and ocean uptake. In addition, it is estimated that an amount equivalent to 30% of recent annual fossil fuel emissions is released into the atmosphere as a result of deforestation and farming. To balance global carbon budget, a sizable carbon sink besides the ocean is needed. Storage of carbon in terrestrial biosphere as a result of C0[sup 2] fertilization is a potential candidate for such missing carbon sinks.

  2. Pulmonary uptake of liposomal phosphatidylcholine.

    PubMed

    Zachman, R D; Tsao, F H

    1980-01-01

    Liposomes prepared with phosphatidylcholine (PC) labeled with [1-14C]-dipalmitoyl-PC, dicetylphosphate, cholesterol (molar ratio 7:2:1) were injected into the right ear vein of 2-month-old male rabbits. At 5, 60, and 120 min after injection, organs were removed and analyzed for [14C]-PC. Lung, liver, and spleen took up the [14C]-PC by 5 min. Spleen accumulation of [14C]-PC increased steadily, liver plateaued from 1--2 hr, and lung fell rapidly. The uptake of liposomal [14C]-PC by lung and liver was dependent on the concentration of iv injected liposomal [14C]-PC. All lung subcellular fractions (lamellar bodies, mitochondria, and microsomes) took up [14C]-PC. Lamellar body [14C]-PC was highest at 5 min, and then decreased. Still, on a nmole/mg protein basis, uptake of [14C]-PC by lamellar bodies was higher than other organelle fractions. Of the radioactivity in lung, 95% was [14C]-PC even after 2 hr, whereas by 1 hr, 28% of liposomal PC absorbed by liver had been degraded. PMID:7360518

  3. Uptake of Workplace HIV Counselling and Testing: A Cluster-Randomised Trial in Zimbabwe

    PubMed Central

    Corbett, Elizabeth L; Dauya, Ethel; Matambo, Ronnie; Cheung, Yin Bun; Makamure, Beauty; Bassett, Mary T; Chandiwana, Steven; Munyati, Shungu; Mason, Peter R; Butterworth, Anthony E; Godfrey-Faussett, Peter; Hayes, Richard J

    2006-01-01

    Background HIV counselling and testing is a key component of both HIV care and HIV prevention, but uptake is currently low. We investigated the impact of rapid HIV testing at the workplace on uptake of voluntary counselling and testing (VCT). Methods and Findings The study was a cluster-randomised trial of two VCT strategies, with business occupational health clinics as the unit of randomisation. VCT was directly offered to all employees, followed by 2 y of open access to VCT and basic HIV care. Businesses were randomised to either on-site rapid HIV testing at their occupational clinic (11 businesses) or to vouchers for off-site VCT at a chain of free-standing centres also using rapid tests (11 businesses). Baseline anonymised HIV serology was requested from all employees. HIV prevalence was 19.8% and 18.4%, respectively, at businesses randomised to on-site and off-site VCT. In total, 1,957 of 3,950 employees at clinics randomised to on-site testing had VCT (mean uptake by site 51.1%) compared to 586 of 3,532 employees taking vouchers at clinics randomised to off-site testing (mean uptake by site 19.2%). The risk ratio for on-site VCT compared to voucher uptake was 2.8 (95% confidence interval 1.8 to 3.8) after adjustment for potential confounders. Only 125 employees (mean uptake by site 4.3%) reported using their voucher, so that the true adjusted risk ratio for on-site compared to off-site VCT may have been as high as 12.5 (95% confidence interval 8.2 to 16.8). Conclusions High-impact VCT strategies are urgently needed to maximise HIV prevention and access to care in Africa. VCT at the workplace offers the potential for high uptake when offered on-site and linked to basic HIV care. Convenience and accessibility appear to have critical roles in the acceptability of community-based VCT. PMID:16796402

  4. Is the effect of silicon on rice uptake of arsenate (AsV) related to internal silicon concentrations, iron plaque and phosphate nutrition?

    PubMed

    Guo, W; Zhu, Y-G; Liu, W-J; Liang, Y-C; Geng, C-N; Wang, S-G

    2007-07-01

    Solution culture experiments were conducted to investigate the effects of silicon (Si) on arsenate (As(V)) uptake by rice. The addition of Si to the pretreatment or uptake solution significantly decreased shoot and root As concentrations (P<0.001 and P<0.05). The presence of Si in the pretreatment or uptake solution also significantly decreased shoot P concentrations (P<0.001). The data demonstrated that both internal and external Si inhibited the uptake of As and P. Results of As uptake kinetics showed that the mechanism of the effect of Si on arsenate uptake is not caused by direct competition for active sites of transporters with As. The effect of Si on As uptake was not entirely mediated through the effect of Si on P uptake. Although the addition of Si to pretreatment solutions still significantly decreased shoot and root As concentrations, the extent of reduction became smaller when rice roots were coated with iron plaque. PMID:17175078

  5. Is the effect of silicon on rice uptake of arsenate (AsV) related to internal silicon concentrations, iron plaque and phosphate nutrition?

    PubMed

    Guo, W; Zhu, Y-G; Liu, W-J; Liang, Y-C; Geng, C-N; Wang, S-G

    2007-07-01

    Solution culture experiments were conducted to investigate the effects of silicon (Si) on arsenate (As(V)) uptake by rice. The addition of Si to the pretreatment or uptake solution significantly decreased shoot and root As concentrations (P<0.001 and P<0.05). The presence of Si in the pretreatment or uptake solution also significantly decreased shoot P concentrations (P<0.001). The data demonstrated that both internal and external Si inhibited the uptake of As and P. Results of As uptake kinetics showed that the mechanism of the effect of Si on arsenate uptake is not caused by direct competition for active sites of transporters with As. The effect of Si on As uptake was not entirely mediated through the effect of Si on P uptake. Although the addition of Si to pretreatment solutions still significantly decreased shoot and root As concentrations, the extent of reduction became smaller when rice roots were coated with iron plaque.

  6. Uptake of technetium-99m methylene diphosphonate by fractured and osteoporotic bone after a pulse dose of Vitamin D/sub 3/. [Rats

    SciTech Connect

    Carr, E.A. Jr.; Carroll, M.; Montes, M.; Zielezny, M.

    1985-04-01

    The effect of a pulse dose of Vitamin D/sub 3/ on uptake of (/sup 99m/Tc)MDP by fractured and osteoporotic bone, respectively, was compared with D/sub 3/'s effect on uptake by normal bone in rats. At 4, 7, and 14 days, respectively, after femoral fracture, basal uptake was significantly increased at the fracture site by 336.8, 276.1, and 183.5%, respectively, over the contralateral control site. D/sub 3/-treated rats had lower uptakes than untreated controls at all three fracture sites and at 12 of 15 normal bone sites but analysis of variance showed the uptake differences were not significant. Cortisone-induced osteoporosis caused a significant decrease in basal uptake. The decrease occurred in all nine bone areas studied. D/sub 3/ caused a significant increase in uptake by these osteoporotic bones, but a significant decrease in uptake by the same bones in normal controls. Thus, D/sub 3/ had an effect on uptake by the bone lesion, osteoporosis, that differed from D/sub 3/'s effect on uptake by fracture or normal bone.

  7. Cell uptake survey of pegylated nanographene oxide

    NASA Astrophysics Data System (ADS)

    Vila, M.; Portolés, M. T.; Marques, P. A. A. P.; Feito, M. J.; Matesanz, M. C.; Ramírez-Santillán, C.; Gonçalves, G.; Cruz, S. M. A.; Nieto, A.; Vallet-Regi, M.

    2012-11-01

    Graphene and more specifically, nanographene oxide (GO) has been proposed as a highly efficient antitumoral therapy agent. Nevertheless, its cell uptake kinetics, its influence in different types of cells and the possibility of controlling cellular internalization timing, is still a field that remains unexplored. Herein, different cell types have been cultured in vitro for several incubation periods in the presence of 0.075 mg ml-1 pegylated GO solutions. GO uptake kinetics revealed differences in the agent’s uptake amount and speed as a function of the type of cell involved. Osteoblast-like cells GO uptake is higher and faster without resulting in greater cell membrane damage. Moreover, the dependence on the commonly used PEG nature (number of branches) also influences the viability and cell uptake speed. These facts play an important role in the future definition of timing parameters and selective cell uptake control in order to achieve an effective therapy.

  8. Neutrophil uptake of vaccinia virus in vitro

    SciTech Connect

    West, B.C.; Eschete, M.L.; Cox, M.E.; King, J.W.

    1987-10-01

    We studied human neutrophils for uptake of vaccinia virus. Uptake was determined radiometrically and by electron microscopy. Vaccinia virus was labeled with /sup 14/C or /sup 3/H, incubated with neutrophils, and quantified in neutrophil pellets in a new radiometric phagocytosis assay. Better results were obtained from assays of (/sup 3/H)thymidine-labeled virus; uptake increased through 1 hr and then plateaued. Phagocytosis of 3H-labeled Staphylococcus aureus was normal. Uptake of virus was serum dependent. Hexose monophosphate shunt activity was measured by two methods. No /sup 14/CO/sub 2/ from (/sup 14/C)1-glucose accompanied uptake of vaccinia virus, in contrast to the respiratory burst accompanying bacterial phagocytosis. Electron microscopy showed intact to slightly digested intraphagolysosomal vaccinia virus. Pock reduction assay showed a decrease in viral content due to neutrophils until 6 hr of incubation, when a modest but significant increase was observed. Thus, neutrophil uptake of vaccinia virus is distinguished from bacterial phagocytosis.

  9. Specific uptake of serotonin by murine lymphoid cells

    SciTech Connect

    Jackson, J.C.; Walker, R.F.; Brooks, W.H.; Roszman, T.L.

    1986-03-01

    Recently the authors confirmed and extended earlier observations that serotonin (5-hydroxytryptamine, 5HT) can influence immune function. Both 5HT and its precursor, 5-hydroxytryptophan inhibit the primary, in vivo antibody response to sheep red blood cells, in mice. Here, the authors report specific in vitro association of this amine with mouse splenocytes. Spleen cells from 6-8 week old CBA/J mice incorporated /sup 3/H-5HT(10/sup -8/ to 2.5 x 10/sup -6/M) in a saturable manner, at 37/sup 0/C. Specificity of uptake was indicated by competition with excess (10/sup -5/M) unlabelled 5HT and with 10/sup -5/M fluoxetine, a selective inhibitor of active 5HT reuptake in rat brain. The 5HT receptor antagonists, methysergide and cyproheptadine, also blocked 5HT uptake. Cell lysis and displacement studies revealed largely intracellular accumulation of /sup 3/H-5HT with little membrane association, in splenocytes. Hofstee analysis of uptake kinetics yielded an apparent Km of 0.82 +/- 0.22 x 10/sup -7/M and Vmax of 501 +/- 108 pM/3 x 10/sup 6/ cells/10 min. Spleen cells fractionated on Sephadex G10 showed virtually no specific 5HT uptake while peritoneal exudate cells from thioglycollate treated mice displayed 5HT uptake kinetics similar to those of splenocytes. The site of specific /sup 3/H-5HT incorporation within a population of spleen cells and the functional significance of this phenomenon to immunomodulation by 5HT remain to be elucidated.

  10. Ethanol intake and sup 3 H-serotonin uptake II: A study in alcoholic patients using platelets sup 3 H-paroxetine binding

    SciTech Connect

    Daoust, M.; Boucly, P. ); Ernouf, D. ); Breton, P. ); Lhuintre, J.P.

    1991-01-01

    The kinetic parameters of {sup 3}H-paroxetine binding and {sup 3}H-serotonin uptake were studied in platelets of alcoholic patients. There was no difference between alcoholic and non alcoholic subjects in {sup 3}H-paroxetine binding. When binding and {sup 3}H-serotonin uptake were studied, in the same plasma of the same subjects, the Vmax of serotonin uptake was increased in alcoholics. The data confirm the involvement of serotonin uptake system in alcohol dependance and suggest that serotonin uptake and paroxetine binding sites may be regulated independently in this pathology.

  11. Monitoring iron uptake by siderophores.

    PubMed

    Hoegy, Françoise; Schalk, Isabelle J

    2014-01-01

    Iron is an important element for almost all forms of life. In order to get access to this essential nutriment, Pseudomonads produce two major siderophores, pyoverdine PVD and pyochelin (PCH). Uptake of iron in bacterial cells can be monitored accurately using (55)Fe. Bacteria cells are incubated in the presence of either PVD or PCH loaded with (55)Fe. After incubation, extracellular iron ions are separated from those accumulated in the bacteria cells by either centrifugation or filtration on glass microfiber filters, for the PCH and PVD assays, respectively. (55)Fe contained in the harvested cells on the filter or in the cell pellet is counted in scintillation cocktail. The number of moles of (55)Fe transported can be determined using the specific activity of the radionuclide. PMID:24818918

  12. Lysimeter study of vegetative uptake from saltstone

    SciTech Connect

    Murphy, C.E. Jr.

    1990-06-08

    At the Savannah River Site, liquid, low-level nuclear waste will be disposed of by incorporating the waste in concrete, a wasteform called saltstone. Saltstone monoliths will then be buried in the earth. To study the potential uptake of radionuclides by trees and other plants growing in the soil in the area containing buried saltstone, a lysimeter study has been in progress since 1984. Thirty two lysimeters were designed, constructed, and filled with soil. Saltstone samples, containing the liquid, low-level supernate from the tank 50 in-tank precipitation demonstration, were buried in some of the lysimeters. Other lysimeters, not containing saltstone, were used as controls. Crops, grass, and trees were planted in the lysimeters and sampled periodically to determine radionuclide concentrations. Water samples were also collected from the lysimeter sumps and analyzed for radionuclide content. This report documents the results of vegetative and lysimeter sump water measurements from the beginning of the project in November of 1984 through September of 1989. 6 refs., 22 figs., 6 tabs.

  13. Uptake, Distribution and Speciation of Chromium

    SciTech Connect

    Bluskov,S.; Arocena, J.; Omotoso, O.; Young, J.

    2005-01-01

    Brassica juncea (Indian mustard) has been widely used in phytoremediation because of its capacity to accumulate high levels of chromium (Cr) and other metals. The present study was conducted to investigate mechanism(s) involved in Cr binding and sequestration by B. juncea. The plants were grown under greenhouse conditions in field-moist or air-dried soils, amended with 100 mg kg -1 of Cr (III or VI). The plant concentrated Cr mainly in the roots. B. juncea removed an average of 48 and 58 {mu}g Cr per plant from Cr (III) and Cr (VI)-treated soils, respectively. The uptake of Cr was not affected by the moisture status of the soils. X-ray absorption near-edge spectroscopy measurements showed only Cr (III) bound predominantly to formate and acetate ligands, in the bulk and rhizosphere soils, respectively. In the plant tissues, Cr (III) was detected, primarily as acetate in the roots and oxalate in the leaves. X-ray microprobe showed the sites of Cr localization, and probably sequestration, in epidermal and cortical cells in the roots and epidermal and spongy mesophyll cells in the leaves. These findings demonstrate the ability of B. juncea to detoxify more toxic Cr (VI), thereby making this plant a potential candidate for phytostabilization.

  14. Physiology, morphology, and ozone uptake of leaves of black cherry seedlings, saplings, and canopy trees.

    PubMed

    Fredericksen, T S; Joyce, B J; Skelly, J M; Steiner, K C; Kolb, T E; Kouterick, K B; Savage, J E; Snyder, K R

    1995-01-01

    Patterns of ozone uptake were related to physiological, morphological, and phenological characteristics of different-sized black cherry trees (Prunus serotina Ehrh.) at a site in central Pennsylvania. Calculated ozone uptake differed among open-grown seedlings, forest gap saplings, and canopy trees and between leaves in the upper and lower crown of saplings and canopy trees. On an instantaneous basis, seedling leaves had the greatest ozone uptake rates of all tree size classes due to greater stomatal conductance and higher concentrations of ozone in their local environment. A pattern of higher stomatal conductance of seedlings was consistent with higher incident photosynthetically-active radiation, stomatal density, and predawn xylem water potentials for seedlings relative to larger trees. However, seedlings displayed an indeterminate pattern of shoot growth, with the majority of their leaves produced after shoot growth had ceased for canopy and sapling trees. Full leaf expansion occurred by mid-June for sapling and canopy trees. Because many of their leaves were exposed to ozone for only part of the growing season, seedlings had a lower relative exposure over the course of the growing season, and subsequently lower cumulative uptake, of ozone than canopy trees and a level of uptake similar to upper canopy leaves of saplings. Visible injury symptoms were not always correlated with patterns in ozone uptake. Visible symptoms were more apparent on seedling leaves in concurrence with their high instantaneous uptake rates. However, visible injury was more prevalent on leaves in the lower versus upper crown of canopy trees and saplings, even though lower crown leaves had less ozone uptake. Lower crown leaves may be more sensitive to ozone per unit uptake than upper crown leaves because of their morphology. In addition, the lower net carbon uptake of lower crown leaves may limit repair and anti-oxidant defense processes. PMID:15091517

  15. Riboflavin uptake by the human-derived liver cells Hep G2: mechanism and regulation.

    PubMed

    Said, H M; Ortiz, A; Ma, T Y; McCloud, E

    1998-09-01

    The water-soluble vitamin riboflavin (RF) plays a critical role in many metabolic reactions, and thus, is essential for normal cellular functions and growth. The liver plays a central role in normal RF metabolism and is the site of maximal utilization of the vitamin. The mechanism of liver uptake of RF has been studied in animals, but no information is available describing the mechanism of the vitamin uptake in the human situation and its cellular regulation. In this study, we used the human-derived liver cells Hep G2 as an in vitro model system to address these issues. Uptake of RF by Hep G2 cells was found to be temperature- and energy-dependent but Na+-independent in nature. Uptake seemed to involve a carrier-mediated process as indicated by the saturation as a function of substrate concentration (apparent Km 0.41 +/- 0.08 microM), and by the ability of the structural analogs lumiflavin and lumichrome to inhibit the uptake process [inhibition constant (K) of 1.84 and 6.32 microM, respectively]. RF uptake was energy dependent, and was inhibited by the -SH group blocker p-chloromercuriphenylsulfonate (p-CMPS) (Ki of 0.10 mM). Specific modulators of intracellular protein kinase A (PKA)-, protein kinase C (PKC)-, and protein tyrosine kinase (PTK)-mediated pathways did not affect RF uptake by Hep G2 cells. On the other hand, specific inhibitors of Ca2+/calmodulin-mediated pathway significantly inhibited the uptake process; this effect seemed to be mediated through a decrease in the Vmax of the substrate uptake process. Maintaining Hep G2 cells in a RF-deficient growth medium was associated with a significant up-regulation in the substrate uptake; this effect was specific for RF and was mediated mainly by means of an increase in the Vmax of the uptake process. These results describe, for the first time, the mechanism and cellular regulation of RF uptake by a human-derived liver cellular preparation, and shows the involvement of a carrier-mediated system in the uptake

  16. Effect of Uptake-one inhibitors on the uptake of norepinephrine and metaiodobenzylguanidine

    SciTech Connect

    Tobes, M.C.; Jaques, S. Jr.; Wieland, D.M.; Sisson, J.C.

    1985-08-01

    The mechanisms underlying the uptake of the radiopharmaceutical metaiodobenzylguanidine (MIBG) and the catecholamine norepinephrine (NE) were studied using cultured bovine adrenomedullary cells as an in vitro model system. Sodium-dependent and sodium-independent uptake systems have been identified and characterized for both MIBG and NE. The sodium-dependent uptake of Ne and MIBG was inhibited by the selective Uptake-one inhibitors, desmethylimipramine (DMI) and cocaine, whereas the sodium-independent uptake for NE and MIBG was much less sensitive to inhibition by these agents. The sodium-dependent uptake system fulfills the criteria for the neuronal Uptake-one system, and the sodium-independent uptake system fulfills the criteria for a passive diffusion mechanism. Arterial concentrations proximal to the dog adrenal were very small suggesting that the sodium-dependent (Uptake-one) system is predominant in vivo. Consistent with the in vitro observations, the in vivo uptake of MIBG and NE into dog adrenal medullae was effectively blocked by pretreatment with DMI or cocaine. Therefore, iodine-131 MIBG scintigraphy of the adrenal appears to reflect uptake by way of the Uptake-one system.

  17. Corrective Feedback and Learner Uptake in CALL

    ERIC Educational Resources Information Center

    Heift, Trude

    2004-01-01

    This paper describes a study in which we investigated the effects of corrective feedback on learner uptake in CALL. Learner uptake is here defined as learner responses to corrective feedback in which, in case of an error, students attempt to correct their mistake(s). 177 students from three Canadian universities participated in the study during…

  18. Incidental fleurodeoxyglucose uptake in the prostate

    PubMed Central

    Wong, W L; Moule, R N; Nunan, T

    2010-01-01

    This commentary confirms the rarity of prostatic cancer associated with incidental prostatic fleurodeoxyglucose (FDG) uptake. The study adds to the literature by showing that even if a prostate lesion is FDG avid it is unlikely to be due to cancer. The commentary considers the management of incidental prostate FDG uptake on the basis of the available evidence. PMID:20965899

  19. Gallium-67 pulmonary uptake in eosinophilic pneumonia

    SciTech Connect

    Morais, J.; Carrier, L.; Gariepy, G.; Le Bel, L.; Chartrand, R.; Picard, D.

    1988-01-01

    Eosinophilic pneumonia is usually diagnosed based on the findings on chest x-ray, white blood count, and transbronchial biopsy. After reporting a case of Ga-67 lung uptake in eosinophilic pneumonia, its histopathology is discussed and the mechanisms of Ga-67 uptake by inflammatory lesions are reviewed.

  20. Cellular uptake of neutral phosphorodiamidate morpholino oligomers.

    PubMed

    Iversen, Patrick L; Aird, Katherine M; Wu, Rebecca; Morse, Michael M; Devi, Gayathri R

    2009-09-01

    Phosphorodiamidate morpholino oligomers (PMO), which have a neutral chemistry, are extensively being used as tools for selective inhibition of gene expression in cell culture models and are currently in human clinical trials. Unlike phosphorothioates (PS ODN) and other charged oligonucleotides, little is known about the uptake characteristics of neutral oligomers. The purpose of this study was to understand the kinetics of PMO transport in cells and correlate with antisense activity. In contrast to primary cells and some transformed cell lines which were uptake permissive, established cancer cell lines showed very poor uptake with an occasional diffuse intracellular pattern. Differential PMO uptake was also observed in immune cells, with dendritic cells and monocytes showing highest uptake compared to T and B cells. In addition, PMO localization was observed to be heterogeneous within a population of uptake permissive cells. Unassisted PMO delivery targeting specific genes was correlated with functional antisense efficacy in experiments showing correction of pre-mRNA missplicing and inhibition of target enzyme activity in cells in culture. PMO internalization in uptake-permissive cells was identified to be specific, saturable, and energy-dependent, suggesting a receptor mediated uptake mechanism. Understanding PMO transport should facilitate the design of more effective synthetic antisense oligomers as therapeutic agents.

  1. Glucose metabolism in sediments of a eutrophic lake: tracer analysis of uptake and product formation.

    PubMed

    King, G M; Klug, M J

    1982-12-01

    The uptake of glucose and the formation of end products from glucose catabolism have been measured for sediments of eutrophic Wintergreen Lake with a combination of tritiated and C-labeled tracers. Time course analyses of the loss of [H]glucose from sediments were used to establish rate constants for glucose uptake at natural substrate concentrations. Turnover times from these analyses were about 1 min for littoral and profundal sediments. No seasonal or site differences were noted in turnover times. Time course analyses of [U-C]glucose uptake and C-labeled end product formation indicated that glucose mass flow could not be calculated from end product formation since the specific activity of added [C]glucose was significantly diluted by pools of intracellular glucose and glucose metabolites. Mass flow could only be accurately estimated by use of rates of uptake from tracer studies. Intermediate fermentation end products included acetate (71%), propionate (15%), lactate (9%), and only minor amounts of butyrates or valerates. Addition of H(2) to sediments resulted in greater production of lactate (28%) and decreased formation of acetate (50%), but did not affect glucose turnover. Depth profiles of glucose uptake indicated that rates of uptake decreased with depth over the 0- to 18-cm interval and that glucose uptake accounted for 30 to 40% of methanogenesis in profundal sediments.

  2. Sorptive uptake of selenium with magnetite and its supported materials onto activated carbon.

    PubMed

    Kwon, Jae H; Wilson, Lee D; Sammynaiken, R

    2015-11-01

    Kinetic and equilibrium uptake studies of selenite in aqueous solution with synthetic magnetite (Mag-P), commercial magnetite (Mag-C), goethite, activated carbon (AC), and a composite material containing 19% magnetite supported on activated carbon (CM-19) were investigated. Kinetic uptake studies used a one-pot setup at pH 5.26 at variable temperature. Sampling of unbound selenite in-situ was achieved with analytical detection by atomic absorbance. The sorptive uptake at equilibrium and kinetic conditions are listed in descending order: goethite>Mag-P>Mag-C>CM-19. Kinetic uptake parameters reveal that Mag-P showed apparent negative values for the activation energy (E(a)) and the enthalpy of activation (ΔH(‡)), in agreement with a multi-step process for the kinetic uptake of selenite. By contrast, Mag-C, CM-19, and goethite showed positive values for E(a) and ΔH(‡). The uptake properties of the various sorbent materials with selenite are in accordance with the formation of inner- and out-sphere complexes. Leaching of iron from the composite material (CM-19) was attenuated due to the stabilizing effect of the magnetite within the pore sites and the surface of AC. Supported iron oxide nanomaterial composites represent a unique sorbent material with tunable uptake properties toward inorganic selenite in aqueous solution.

  3. Electrogenicity of hepatocellular fatty acid uptake.

    PubMed

    Elsing, C; Kassner, A; Gajdzik, L; Graf, J; Stremmel, W

    1998-08-18

    Sensitivity of cellular fatty acids uptake to the membrane potential difference is still a matter of controversy. For direct evaluation of potential sensitivity the effect of changing membrane potential on uptake of a fluorescent long chain fatty acid derivative, 12-NBD-stearate, in isolated rat hepatocytes, was examined. Changes in membrane potential were achieved by patch clamp procedures. Fatty acid influx was simultaneously determined by recording of cell fluorescence. Hyperpolarization from -30 to -70 mV accelerated fatty acid influx whereas depolarization to +50 mV reduced uptake. After obtaining equilibrium hyperpolarization increased cell fluorescence, whereas depolarization pushed NBD-stearate out of cells. Potential sensitivity of uptake was dependent on the fatty acid concentrations in the medium with most prominent effects at low unbound concentrations. These data show that, at low fatty acid concentrations, uptake is, in part, driven by an intracellular negative electric membrane potential.

  4. Highly infectious symbiont dominates initial uptake in coral juveniles.

    PubMed

    Abrego, David; VAN Oppen, Madeleine J H; Willis, Bette L

    2009-08-01

    The majority of reef-building corals acquire their obligate algal symbionts (Symbiodinium) from the environment. However, factors shaping the initial establishment of coral-algal symbioses, including parental effects, local environmental conditions and local availability of symbionts, are not well understood. This study monitored the uptake and maintenance of Symbiodinium in juveniles of two common corals, Acropora tenuis and Acropora millepora, that were reciprocally explanted between sites where adult colonies host different types of Symbiodinium. We found that coral juveniles were rapidly dominated by type D Symbiodinium, even though this type is not found in adult colonies (including the parental colonies) in four out of the five study populations. Furthermore, type D Symbiodinium was found in less than one-third of a wide range of coral species (n > 50) sampled at the two main study sites, suggesting that its dominance in the acroporid juveniles is not because it is the most abundant local endosymbiotic type. Moreover, dominance by type D was observed irrespective of the light intensity to which juveniles were exposed in a field study. In summary, despite its relatively low abundance in coral assemblages at the study sites and irrespective of the surrounding light environment, type D Symbiodinium is the main symbiont type initially acquired by juveniles of A. millepora and A. tenuis. We conclude that during early ontogeny in these corals, there are few barriers to the uptake of Symbiodinium types which differ from those found in parental colonies, resulting in dominance by a highly infectious and potentially opportunistic symbiont.

  5. Controls on tree water uptake and information storage in tree rings

    NASA Astrophysics Data System (ADS)

    Blume, Theresa; Simard, Sonia; Heidbüchel, Ingo; Güntner, Andreas; Heinrich, Ingo

    2016-04-01

    Controls on tree water uptake are investigated in various forest stands in the northeastern German lowlands by a multi-method approach. This approach combines sapflow and dendrometer measurements as well as tree-ring analyses with soil moisture derived root water uptake rates. The latter method has the advantage that it provides depth distributions of root water uptake and thus additional information allowing for a more detailed analysis of the relationship between water availability and water uptake. High resolution climatic data makes it possible to investigate the site specific interplay between atmospheric demand and water availability on the one hand and tree response and adaptation on the other hand. The comparison of spatio-temporal patterns of these responses with concurrent tree growth as well as tree-ring analyses enables a first matching of actual and "archived" patterns and thus an estimate of how much of this information is stored in tree rings.

  6. Phytoplankton productivity, respiration, and nutrient uptake and regeneration in the Potomac River, August 1977 - August 1978

    USGS Publications Warehouse

    Cole, B.E.; Harmon, D.D.

    1981-01-01

    Rates of phytoplankton productivity, respiration, and nutrient uptake and regeneration are presented. These observations were made on the Potomac River estuary (POTE) during four cruises between August 1977 and August 1978. Four experimental methods were used: carbon uptake using carbon-14, carbon uptake and respiration by a pH method, productivity and respiration by the dissolved oxygen method, and nutrient (NH4+, NO3-, NO2-, PO4=, and SiO2=) uptake and regeneration by colorimetry. The experiments were made at sites representative of conditions in four principal reaches of the tidal Potomac River estuary: near the mouth, seaward of the summer nutrient and phytoplankton maximum, near the region of maximum phytoplankton standing stock , and near the maximum anthropogenic nutrient source. (USGS)

  7. Cadmium and calcium uptake in the mollusc donax rugosus and effect of a calcium channel blocker

    SciTech Connect

    Sidoumou, Z.; Gnassia-Barelli, M.; Romeo, M.

    1997-02-01

    Donax rugosus, a common bivalve mollusc in the coastal waters of Mauritania, has been studied for trace metal concentrations as a function of sampling site (from South of Mauritania to the North of this country) and of season. In this paper, the uptake of cadmium was experimentally studied in the different organs of D. rugosus. Since metals such as cadmium, copper and mercury may alter calcium homeostasis, calcium uptake was also studied in the animals treated with cadmium. Since calcium is taken up through specific channels, it appears that metals inhibit Ca uptake by interacting with these channels in the plasma membrane. Cadmium and calcium have very similar atomic radii, thus cadmium may be taken up through the calcium channels, particularly through voltage-dependent channels. The uptake of cadmium and calcium by D. Rugosus was therefore also studied in the presence of the calcium channel blocker verapamil. 13 refs., 3 figs., 1 tab.

  8. Technetium-99m-HDP uptake characteristics in equine fractures: a retrospective study.

    PubMed

    Scheidegger, E; Geissbühlerl, U; Doherr, M G; Lang, J

    2006-10-01

    Bone scintigraphy is a very sensitive diagnostic tool to detect elevated bone metabolism. In cases of fractures and fissure fractures, the radiopharmaceutical uptake in the bone is said to be increased within a few hours after the injury. In this retrospective study, the scintigraphic uptake characteristics at the fracture site of 36 horses with radiographically confirmed fractures or fissure fractures were evaluated. Uptake ratios between the fracture region and adjacent normal bone or soft tissue activity respectively were calculated and compared to different anamnestic and radiographic data. The overall sensitivity of bone scintigraphy was 94.4% (34 positive cases out of 36). In the 36 horses, no correlation between the age of the fracture and the radiopharmaceutical uptake was found. However, there seems to be a lack of sensitivity in early detection of equine pelvic fractures when a standing bone scintigraphy examination protocol is used.

  9. Modification of nitrate uptake pathway in plants affects the cadmium uptake by roots.

    PubMed

    Guan, Mei Yan; Fan, Shi Kai; Fang, Xian Zhi; Jin, Chong Wei

    2015-01-01

    NRT1.1 is a dual-affinity nitrate (NO3(-)) transporter involved in both high- and low-affinity NO3(-) uptake in Arabidopsis plants. In a recent study, we showed that, under cadmium (Cd) exposure, blocking the NRT1.1-mediated NO3(-) uptake reduces Cd entry into roots, thus lowing Cd levels in plants and improving plant growth. In addition, we also found that the Cd levels in edible parts of 11 Chinese cabbage (Brassica rapa L. ssp. pekinensis) cultivars correlated well with the NO3(-) uptake rates of their roots. These results suggested that the NO3(-) uptake of roots negatively regulate Cd uptake. Modification of NO3(-) uptake in crops by modulating NO3(-) uptake pathway might provide a biological engineering approach to reducing Cd accumulation in edible organs, thus improving food safety.

  10. Plant-uptake of uranium: Hydroponic and soil system studies

    USGS Publications Warehouse

    Ramaswami, A.; Carr, P.; Burkhardt, M.

    2001-01-01

    Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus giganteus), Spring Vetch (Vicia sativa), Hairy Vetch (Vicia villosa), Juniper (Juniperus monosperma), Indian Mustard (Brassica juncea), and Bush Bean (Phaseolus nanus). Plant performance was evaluated both in terms of the percent uranium extracted from the three systems, as well as the biological absorption coefficient (BAC) that normalized uranium uptake to plant biomass. Study results indicate that uranium extraction efficiency decreased sharply across hydroponic, sandy and organic soil systems, indicating that soil organic matter sequestered uranium, rendering it largely unavailable for plant uptake. These results indicate that site-specific soils must be used to screen plants for uranium extraction capability; plant behavior in hydroponic systems does not correlate well with that in soil systems. One plant species, Juniper, exhibited consistent uranium extraction efficiencies and BACs in both sandy and organic soils, suggesting unique uranium extraction capabilities.

  11. The uptake of water hardness metals by human hair.

    PubMed

    Evans, A O; Marsh, J M; Wickett, R R

    2011-01-01

    The objective of this work was to examine the variables that influence the interaction between water hardness metals and human hair. Hair extracts various constituents from the tap water used during daily hygiene practices and chemical treatments. Calcium and magnesium metal ions are the most prevalent and give water "hardness." Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was employed to quantify the metal content of hair, which was studied as a function of the following variables: hair condition (oxidative damage), level of water hardness, and water pH. We have demonstrated that these variables impact water hardness metal uptake to varying extents, and the effects are driven primarily by the binding capacity (available anionic sites) of the hair. The condition of the hair, a key representation of the binding capacity, was most influential. Interestingly, water hardness levels had only a small effect on uptake; hair became saturated with notable amounts of water hardness metals even after repeated exposure to soft water. Water pH influenced metal uptake since side chains of hair proteins deprotonate with increasing alkalinity. These insights highlight the importance to the hair care industry of understanding the interaction between water hardness metals and hair.

  12. Cystine and dibasic amino acid uptake by opossum kidney cells

    SciTech Connect

    States, B.; Segal, S. )

    1990-06-01

    The characteristics of the uptake of L-cystine by the continuous opossum kidney cell line, OK, were examined. Uptake of cystine is rapid and, in contrast to other continuous cultured cell lines, these cells retain the cystine/dibasic amino acid transport system which is found in vivo and in freshly isolated kidney tissue. Confluent monolayers of cells also fail to show the presence of the cystine/glutamate transport system present in LLC-PK1 cells, fibroblasts, and cultured hepatocytes. Uptake of cystine occurs via a high-affinity saturable process which is independent of medium sodium concentration. The predominant site of cystine transport is across the apical cell membrane. The intracellular concentration of GSH far exceeds that of cystine with a ratio greater than 100:1 for GSH:cysteine. Incubation of cells for 5 minutes with a physiological level of labelled cystine resulted in the labelling of 66% and 5% of the total intracellular cysteine and glutathione, respectively. The ability of these cells to reflect the shared cystine/dibasic amino acid transport system makes them a suitable model for investigation of the cystine carrier which is altered in human cystinuria.

  13. Radiostrontium uptake by plants from different soil types in Kazakhstan.

    PubMed

    Savinkov, A; Semioshkina, N; Howard, B J; Voigt, G

    2007-02-01

    The transfer of 90Sr to a range of different plant species grown on a range of different soil types in Kazakhstan, including three from the Semipalatinsk Test Site (STS), has been measured in a lysimeter experiment. 90Sr uptake by Stipa spp was significantly higher than for other vegetation species. The uptake of 90Sr from chernozem was significantly lower than that from the other soil types which is consistent with other literature. There was a significant negative relationship between 90Sr uptake and calcium, humus and CEC concentration in the soil for Agropyrum spp, Artemisia spp but not for Stipa spp or Bromus spp. The transfer to vegetation from soil has been quantified using the aggregated transfer coefficients for each species. Tag values range from 0.6 to 11.9 m2 kg-1x10(-3) over all measurements. The transfer of 90Sr to plants from the Kazakh soils was low compared to previously reported data and to that given from literature reviews.

  14. Temperature responses of carbon monoxide and hydrogen uptake by vegetated and unvegetated volcanic cinders

    PubMed Central

    King, Caitlin E; King, Gary M

    2012-01-01

    Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 °C) to extreme (55 °C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14–25 °C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H2) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H2 uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H2 uptake was less sensitive than Bare H2 uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 °C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H2 uptake for material from both sites was completely inhibited at 55 °C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material. PMID:22258097

  15. Variable effects of plant colonization on black slate uptake into microbial PLFAs

    NASA Astrophysics Data System (ADS)

    Seifert, Anne-Gret; Trumbore, Susan; Xu, Xiaomei; Zhang, Dachung; Gleixner, Gerd

    2013-04-01

    Microbial degradation of carbon derived from black shale and slate has been shown in vitro. However, in natural settings where other labile carbon sources are likely to exist, this has not been previously demonstrated. We investigated the uptake of ancient carbon derived from slate weathering and from recently photosynthesised organic matter by different groups of microorganisms. Therefore we isolated microbial biomarkers (phospholipid fatty acids, PLFAs) from black slates collected at a chronosequence of waste piles which differed in age and vegetation cover. We quantified the amount of PLFAs and performed stable isotope and radiocarbon measurements on individual or grouped PLFAs to quantify the fraction of slate derived carbon. We used black slate from a pile heaped in the 1950s with either uncovered black slate material (bare site) or material slightly colonized by small plants (greened site) and from a forested leaching pile (forested site) used for alum-mining in the 19th century. Colonization by plants influenced the amount and composition of the microbial community. Greater amounts of PLFAs (5410 ng PLFA/g dw) were extracted from slate sampled at the forested site as opposed to the bare site (960 ng PLFAs/g dw) or the greened (annual grasses and mosses) rock waste pile (1050 ng PLFAs/g dw). We found the highest proportion of PLFAs representing Gram-negative bacteria on the forested site and the highest proportion of PLFAs representing Gram-positive bacteria on the bare site. The fungal PLFA was most abundant at the greened site. Sites with less plant colonization (bare and greened site) tended to have more depleted δ13C values compared to the forested site. Radiocarbon measurements on PLFAs indicated that fungi and Gram-positive bacteria were best adapted to black slate carbon uptake. In the fungal PLFA (combined bare and greened waste pile sample) and in PLFAs of Gram-positive bacteria (greened site) we measured 39.7% and 28.9% ancient carbon uptake

  16. A statistical approach to estimate O3 uptake of ponderosa pine in a mediterranean climate.

    PubMed

    Grulke, N E; Preisler, H K; Fan, C C; Retzlaff, W A

    2002-01-01

    In highly polluted sites, stomatal behavior is sluggish with respect to light, vapor pressure deficit, and internal CO2 concentration (Ci) and poorly described by existing models. Statistical models were developed to estimate stomatal conductance (gs) of 40-year-old ponderosa pine at three sites differing in pollutant exposure for the purpose of calculating O3 uptake. Gs was estimated using julian day, hour of day, pre-dawn xylem potential and photosynthetic photon flux density (PPFD). The median difference between estimated and observed field gs did not exceed 10 mmol H2O m(-2) s(-1), and estimated gs within 95% confidence intervals. 03 uptake was calculated from hourly estimated gs, hourly O3 concentration, and a constant to correct for the difference in diffusivity between water vapor and 03. The simulation model TREGRO was also used to calculate the cumulative 03 uptake at all three sites. 03 uptake estimated by the statistical model was higher than that simulated by TREGRO because gas exchange rates were proportionally higher. O3 exposure and uptake were significantly correlated (r2>0.92), because O3 exposure and gs were highly correlated in both statistical and simulation models. PMID:12152824

  17. Uptake of perchlorate in terrestrial plants.

    PubMed

    Yu, Lu; Cañas, Jaclyn E; Cobb, George P; Jackson, William A; Anderson, Todd A

    2004-05-01

    Cucumber (Cucumis sativus L.), lettuce (Lactuca sativa L.), and soybean (Glycine max) were used to determine uptake of the perchlorate anion (100 ppb) from sand. Plants were watered with different ratios of Hydrosol (a diluted solution of Peters All-Purpose Plant Food) to Milli-Q water (18 MOmega) to determine if the presence of other nutrients (such as nitrate) influenced perchlorate uptake. Perchlorate concentrations in sand and plant tissues were determined weekly. Perchlorate uptake was observed in all three plant species. In most experiments, perchlorate was completely depleted from sand in which plants were growing. Perchlorate concentrations in lettuce were also significantly higher than those in cucumber and soybean (P < 0.0001). Perchlorate concentrations in sand decreased at a higher rate at lower ratios of Hydrosol to Milli-Q, indicating that plant (cucumber) uptake of perchlorate is influenced by the presence of external nutrients. The results of an 8-week uptake study in cucumber and a 6-week uptake study in lettuce suggest that a threshold perchlorate concentration is reached: for cucumber, 150 ppm and for lettuce, 750 ppm. Although the presence of external nutrients decreases the rate of perchlorate uptake by plants, significant concentrations of perchlorate occur in aboveground plant tissues even after relatively short periods of growth. The potential for trophic transfer of perchlorate from soil to higher organisms through plants exists.

  18. FDG uptake, a surrogate of tumour hypoxia?

    PubMed Central

    Van de Wiele, Christophe

    2008-01-01

    Introduction Tumour hyperglycolysis is driven by activation of hypoxia-inducible factor-1 (HIF-1) through tumour hypoxia. Accordingly, the degree of 2-fluro-2-deoxy-d-glucose (FDG) uptake by tumours might indirectly reflect the level of hypoxia, obviating the need for more specific radiopharmaceuticals for hypoxia imaging. Discussion In this paper, available data on the relationship between hypoxia and FDG uptake by tumour tissue in vitro and in vivo are reviewed. In pre-clinical in vitro studies, acute hypoxia was consistently shown to increase FDG uptake by normal and tumour cells within a couple of hours after onset with mobilisation or modification of glucose transporters optimising glucose uptake, followed by a delayed response with increased rates of transcription of GLUT mRNA. In pre-clinical imaging studies on chronic hypoxia that compared FDG uptake by tumours grown in rat or mice to uptake by FMISO, the pattern of normoxic and hypoxic regions within the human tumour xenografts, as imaged by FMISO, largely correlated with glucose metabolism although minor locoregional differences could not be excluded. In the clinical setting, data are limited and discordant. Conclusion Further evaluation of FDG uptake by various tumour types in relation to intrinsic and bioreductive markers of hypoxia and response to radiotherapy or hypoxia-dependent drugs is needed to fully assess its application as a marker of hypoxia in the clinical setting. PMID:18509637

  19. Does elevated CO2 alter silica uptake in trees?

    PubMed

    Fulweiler, Robinson W; Maguire, Timothy J; Carey, Joanna C; Finzi, Adrien C

    2014-01-01

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, long-term free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.

  20. Does elevated CO2 alter silica uptake in trees?

    DOE PAGES

    Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; Finzi, Adrien C.

    2015-01-13

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, longterm free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwoodmore » species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.« less

  1. Does elevated CO2 alter silica uptake in trees?

    PubMed Central

    Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; Finzi, Adrien C.

    2015-01-01

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, long-term free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems. PMID:25628636

  2. The K+/site and H+/site stoichiometry of mitochondrial electron transport.

    PubMed

    Reynafarje, B; Lehninger, A L

    1978-09-25

    Electrode measurements of the average number of H+ ejected and K+ taken up (in the presence of valinomycin) per pair of electrons passing the energy-conserving sites of the respiratory chain of rat liver and rat heart mitochondria have given identical values of the H+/site and 5+/site ratios very close to 4 in the presence of N-ethylmaleimide, an inhibitor of interfering respiration-coupled uptake of H+ + H2PO4-. The K+/site uptake ratio of 4 not only shows that inward movement of K+ provides quantitative charge-compensation for the 4 H+ ejected, but also confirms that 4 charges are separated per pair of electrons per site. When N-ethylmaleimide is omitted, the H+/site ejection ratio is depressed, because of the interfering secondary uptake of H/+ with H2PO4- on the phosphate carrier, but the K+/site uptake ratio remains at 4.0. Addition of phosphate or acetate, which can carry H+ into respiring mitochondria, further depresses the H+/site ratio, but does not affect the K+/site ratio, which remains at 4.0. These and other considerations thus confirm our earlier stoichiometric measurements that the average H+/site ratio is 4.0 and also show that the K+/site uptake ratio can be used as a measure of the intrinsic H+/site ratio, regardless of the presence of phosphate in the medium and without the necessity of adding N-ethylmaleimide or other inhibitors of H+ + H2PO4- transport.

  3. Uptake of fluorine-18-fluorodeoxyglucose in sarcoidosis

    SciTech Connect

    Lewis, P.J.; Salama, A.

    1994-10-01

    Whole-body PET scanning was performed using {sup 18}F-fluorodeoxyglucose (FDG) in two patients with hilar lymphadenopathy in whom the clinical differential diagnosis was between sarcoidosis and lymphoma. Both patients were later proven to have sarcoidosis. Uptake of {sup 18}FDG was seen in both intra- and extrathoracic lesions as well as in associated erythema nodosum. One patient underwent a repeat scan after steroid therapy where a marked decrease in hilar uptake was seen. Fluorine-18-fluorodeoxyglucose uptake is observed in lymph nodes with sarcoid involvement. Further investigation is necessary to assess if quantitative differences exist between sarcoid and malignant lymphadenopathy. 30 refs., 3 figs.

  4. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    SciTech Connect

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-19

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  5. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    NASA Astrophysics Data System (ADS)

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-01

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  6. Sphagnum mosses--masters of efficient N-uptake while avoiding intoxication.

    PubMed

    Fritz, Christian; Lamers, Leon P M; Riaz, Muhammad; van den Berg, Leon J L; Elzenga, Theo J T M

    2014-01-01

    Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form ((15)N-ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5-6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands.

  7. Uptake of trimethoprim by renal cortex.

    PubMed

    Cacini, W; Myre, S A

    1985-10-01

    The purpose of this study was to examine the mechanisms involved in the uptake of the urinary antibacterial drug trimethoprim by incubated slices of rat renal cortex. Concentration-dependent studies of the uptake process demonstrated that a saturable component was involved. The results of inhibitor studies as well as the time-course pattern support the conclusion that at least two processes are involved in the uptake of trimethoprim. These include active transport via the organic cation system, accounting for about 40% of the total uptake, and a second component that continues to operate under conditions of inhibited cellular metabolism. Chromatographic examination of post-incubation bathing medium and slice extracts failed to demonstrate renal cortex metabolism of trimethoprim. PMID:4052093

  8. Nitrogen uptake and utilization by intact plants

    NASA Technical Reports Server (NTRS)

    Raper, C. D., Jr.; Tolley-Henry, L. C.

    1986-01-01

    The results of experiments support the proposed conceptual model that relates nitrogen uptake activity by plants as a balanced interdependence between the carbon-supplying function of the shoot and the nitrogen-supplying function of the roots. The data are being used to modify a dynamic simulation of plant growth, which presently describes carbon flows through the plant, to describe nitrogen uptake and assimilation within the plant system. Although several models have been proposed to predict nitrogen uptake and partitioning, they emphasize root characteristics affecting nutrient uptake and relay on empirical methods to describe the relationship between nitrogen and carbon flows within the plant. Researchers, on the other hand, propose to continue to attempt a mechanistic solution in which the effects of environment on nitrogen (as well as carbon) assimilation are incorporated through their direct effects on photosynthesis, respiration, and aging processes.

  9. CONVERGING PATTERNS OF UPTAKE AND HYDRAULIC REDISTRIBUTION OF SOIL WATER IN CONTRASTING WOODY VEGETATION TYPES

    EPA Science Inventory

    We used concurrent measurements of soil water content and soil water potential (Ysoil) to assess the effects of Ysoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles in six sites characterized by different types and amounts of woo...

  10. Gallium-67 uptake in meningeal sarcoidosis

    SciTech Connect

    Ayres, J.G.; Hicks, B.H.; Maisey, M.N.

    1986-07-01

    A case of sarcoidosis limited to the central nervous system is described in which the diagnosis was suggested by high Ga-67 uptake in the cranial and spinal meninges. The diagnosis was confirmed by meningeal biopsy. Treatment with oral corticosteroids resulted in clinical improvement and marked reduction in Ga-67 uptake in the meninges. This is the first reported case of the central nervous system sarcoid diagnosed by Ga-67 imaging.

  11. Diaphragm and Laryngeal FDG Uptake With Hiccups.

    PubMed

    Srivastava, Madhur K; Jain, Avani S; Panneer, Venkat; Muthukrishnan, Indirani; Simon, Shelley

    2015-11-01

    F-FDG PET/CT study is a well-established investigation in diagnosis, treatment evaluation, and follow-up of malignant tumors. It is very important to know the normal biodistribution and physiologic uptake of F-FDG to prevent it from confusing as malignant disease. This article describes unusual but physiological uptake in the laryngeal and diaphragmatic muscles in a patient presenting as metastatic adenocarcinoma with unknown primary having hiccups. PMID:26204217

  12. General aspects of muscle glucose uptake.

    PubMed

    Alvim, Rafael O; Cheuhen, Marcel R; Machado, Silmara R; Sousa, André Gustavo P; Santos, Paulo C J L

    2015-03-01

    Glucose uptake in peripheral tissues is dependent on the translocation of GLUT4 glucose transporters to the plasma membrane. Studies have shown the existence of two major signaling pathways that lead to the translocation of GLUT4. The first, and widely investigated, is the insulin activated signaling pathway through insulin receptor substrate-1 and phosphatidylinositol 3-kinase. The second is the insulin-independent signaling pathway, which is activated by contractions. Individuals with type 2 diabetes mellitus have reduced insulin-stimulated glucose uptake in skeletal muscle due to the phenomenon of insulin resistance. However, those individuals have normal glucose uptake during exercise. In this context, physical exercise is one of the most important interventions that stimulates glucose uptake by insulin-independent pathways, and the main molecules involved are adenosine monophosphate-activated protein kinase, nitric oxide, bradykinin, AKT, reactive oxygen species and calcium. In this review, our main aims were to highlight the different glucose uptake pathways and to report the effects of physical exercise, diet and drugs on their functioning. Lastly, with the better understanding of these pathways, it would be possible to assess, exactly and molecularly, the importance of physical exercise and diet on glucose homeostasis. Furthermore, it would be possible to assess the action of drugs that might optimize glucose uptake and consequently be an important step in controlling the blood glucose levels in diabetic patients, in addition to being important to clarify some pathways that justify the development of drugs capable of mimicking the contraction pathway.

  13. Substrate stiffness regulates cellular uptake of nanoparticles.

    PubMed

    Huang, Changjin; Butler, Peter J; Tong, Sheng; Muddana, Hari S; Bao, Gang; Zhang, Sulin

    2013-04-10

    Nanoparticle (NP)-bioconjugates hold great promise for more sensitive disease diagnosis and more effective anticancer drug delivery compared with existing approaches. A critical aspect in both applications is cellular internalization of NPs, which is influenced by NP properties and cell surface mechanics. Despite considerable progress in optimization of the NP-bioconjugates for improved targeting, the role of substrate stiffness on cellular uptake has not been investigated. Using polyacrylamide (PA) hydrogels as model substrates with tunable stiffness, we quantified the relationship between substrate stiffness and cellular uptake of fluorescent NPs by bovine aortic endothelial cells (BAECs). We found that a stiffer substrate results in a higher total cellular uptake on a per cell basis, but a lower uptake per unit membrane area. To obtain a mechanistic understanding of the cellular uptake behavior, we developed a thermodynamic model that predicts that membrane spreading area and cell membrane tension are two key factors controlling cellular uptake of NPs, both of which are modulated by substrate stiffness. Our experimental and modeling results not only open up new avenues for engineering NP-based cancer cell targets for more effective in vivo delivery but also contribute an example of how the physical environment dictates cellular behavior and function.

  14. Neptunium uptake by serum transferrin.

    PubMed

    Llorens, Isabelle; Den Auwer, Christophe; Moisy, Philippe; Ansoborlo, Eric; Vidaud, Claude; Funke, Harld

    2005-04-01

    Although of major impact in terms of biological and environmental hazards, interactions of actinide cations with biological molecules are only partially understood. Human serum transferrin (Tf) is one of the major iron carriers in charge of iron regulation in the cell cycle and consequently contamination by actinide cations is a critical issue of nuclear toxicology. Combined X-ray absorption spectroscopy (XAS) and near infrared absorption spectrometry were used to characterize a new complex between Tf and Np (IV) with the synergistic nitrilotriacetic acid (NTA) anion. Description of the neptunium polyhedron within the iron coordination site is given.

  15. Endocytosis of the major yolk proteins of the silkmoth, Hyalophora cecropia: Uptake kinetics and interactions

    SciTech Connect

    Kulakosky, P.C.

    1989-01-01

    The oocytes of Lepidopteran insects take up several yolk proteins in defined proportions even though their relative availability in the hemolymph changes during the several days required to complete yolk formation in all the eggs. There are three hemolymph yolk precursors, vitellogenin, microvitellogenin and lipophorin; one precursor, paravitellogenin is produced in the ovary. The control mechanism for their proportional endocytosis is not known. In this thesis, the author describe the purification of all four proteins and the radiolabeling of the hemolymph precursors. The radiolabeled proteins were tested with an in vitro incubation system to assess the biological activity of the proteins and the reliability of the incubation methods. All of the labeled probes were transferred from the incubation medium to yolk spheres within the oocyte in a saturable, energy-dependent, and stage-specific manner. The rates of uptake were similar to the estimated rates of uptake in situ. The concentration dependence of in vitro uptake was investigated and found to be consistent with in situ concentrations and the composition of yolk in mature eggs. Two precursors, vitellogenin and lipophorin, competed for uptake indicating that they share a common binding site while the third, microvitellin, did not compete with the others. Though vitellogenin and lipophorin competed for uptake, only vitellogenin displayed the unique ability to increase the uptake rate of microvitellin and fluid in vitro.

  16. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia.

    PubMed

    Millett, J; Foot, G W; Svensson, B M

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant-prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific.

  17. Caged mussels and semipermeable membrane devices as indicators of organic contaminant uptake in Dorchester and Duxbury Bays, Massachusetts

    SciTech Connect

    Peven, C.S.; Uhler, A.D.; Querzoli, F.J.

    1996-02-01

    An experiment to measure organic contaminant depuration by the blue mussel (Mytilus edulis) was carried out by transplanting mussels in stainless steel cages from a known contaminated site in Dorchester Bay, Massachusetts to a documented clean site in Duxbury Bay, Massachusetts approximately 30 nmi south of the original collection site. A parallel contaminant uptake experiment was performed in which mussels from Duxbury Bay were collected and deployed in similar cages in Dorchester Bay. The bivalves were collected from each transplant site at set intervals over a period of 95 days to monitor the rates and selectivity of depuration and uptake, respectively, of polynuclear atomic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and chlorinated pesticides. In a related study, semipermeable membrane devices (SPMD: polyethylene bags) containing the lipid material triolein were deployed in Dorchester Bay and collected at the same frequency as the caged mussels to evaluate their effectiveness as models for estimating bioconcentration of target organic contaminants. At the Duxbury site, results suggest that the caged mussels depurated contaminants within 68 days to levels found in native animals at the site. At the Dorchester site, bivalves concentrated the contaminants to a level similar to the native M. edulis. PCB and DDT uptake rates were found to be similar between caged mussels and SPMDs; PAH uptake by the SPMDs was initially lower than by transplanted bivalves. PCB and PAH assemblages were noticeably different between bivalves and SPMDs deployed at the same site.

  18. In vivo radiometric analysis of glucose uptake and distribution in mouse bone

    PubMed Central

    Zoch, Meredith L; Abou, Diane S; Clemens, Thomas L; Thorek, Daniel L J; Riddle, Ryan C

    2016-01-01

    Bone formation and remodeling occurs throughout life and requires the sustained activity of osteoblasts and osteoclasts, particularly during periods of rapid bone growth. Despite increasing evidence linking bone cell activity to global energy homeostasis, little is known about the relative energy requirements or substrate utilization of bone cells. In these studies, we measured the uptake and distribution of glucose in the skeleton in vivo using positron-emitting 18F-fluorodeoxyglucose ([18F]-FDG) and non-invasive, high-resolution positron emission tomography/computed tomography (PET/CT) imaging and ex vivo autoradiography. Assessment of [18F]-FDG uptake demonstrated that relative to other tissues bone accumulated a significant fraction of the total dose of the glucose analog. Skeletal accumulation was greatest in young mice undergoing the rapid bone formation that characterizes early development. PET/CT imaging revealed that [18F]-FDG uptake was greatest in the epiphyseal and metaphyseal regions of long bones, which accords with the increased osteoblast numbers and activity at this skeletal site. Insulin administration significantly increased skeletal accumulation of [18F]-FDG, while uptake was reduced in mice lacking the insulin receptor specifically in osteoblasts or fed a high-fat diet. Our results indicated that the skeleton is a site of significant glucose uptake and that its consumption by bone cells is subject to regulation by insulin and disturbances in whole-body metabolism. PMID:27088042

  19. In vivo radiometric analysis of glucose uptake and distribution in mouse bone.

    PubMed

    Zoch, Meredith L; Abou, Diane S; Clemens, Thomas L; Thorek, Daniel L J; Riddle, Ryan C

    2016-01-01

    Bone formation and remodeling occurs throughout life and requires the sustained activity of osteoblasts and osteoclasts, particularly during periods of rapid bone growth. Despite increasing evidence linking bone cell activity to global energy homeostasis, little is known about the relative energy requirements or substrate utilization of bone cells. In these studies, we measured the uptake and distribution of glucose in the skeleton in vivo using positron-emitting (18)F-fluorodeoxyglucose ([(18)F]-FDG) and non-invasive, high-resolution positron emission tomography/computed tomography (PET/CT) imaging and ex vivo autoradiography. Assessment of [(18)F]-FDG uptake demonstrated that relative to other tissues bone accumulated a significant fraction of the total dose of the glucose analog. Skeletal accumulation was greatest in young mice undergoing the rapid bone formation that characterizes early development. PET/CT imaging revealed that [(18)F]-FDG uptake was greatest in the epiphyseal and metaphyseal regions of long bones, which accords with the increased osteoblast numbers and activity at this skeletal site. Insulin administration significantly increased skeletal accumulation of [(18)F]-FDG, while uptake was reduced in mice lacking the insulin receptor specifically in osteoblasts or fed a high-fat diet. Our results indicated that the skeleton is a site of significant glucose uptake and that its consumption by bone cells is subject to regulation by insulin and disturbances in whole-body metabolism. PMID:27088042

  20. Utilization of a Model for Uptake of Cadmium by Plants as a Phytoremediation Assessment Tool

    NASA Astrophysics Data System (ADS)

    Takahashi, M.; Furbish, D. J.; Clarke, J.

    2008-12-01

    Some traditional methods of environmental remediation, such as removal and disposal of contaminated soil, are loosing economic favor and public acceptance, while others, such as in situ phytoremediation, are being carefully examined because of their attractiveness as environmentally friendly, low-cost solutions to site clean-up. The success of phytoremediation strategies, however, hinges on the ability of selected plants, or plant communities, to effectively uptake, accumulate and tolerate targeted contaminants. Heavy metals, specifically cadmium (Cd), are not essential nutrients to plants. However, chemically similar zinc (Zn) is a micronutrient and is actively taken up by hyperaccumulators. For this reason, the mechanisms involved in uptake of Cd parallel those of Zn. Ideally, Cd would be allocated to the stem, leaf, and/or flower, where it becomes harvestable. Our modeling work simulates the uptake and the storage of Cd in a growing hyperaccumulator. After uptake, Cd is partitioned between adsorption to plant tissue and upward movement to leaves driven by transpiration. Uptake, adsorption and transport are also regulated by phytotoxicity. Simulations suggest that a young plant with small biomass can quickly reach phytotoxicity, which shuts down the normal operation of the plant. Conversely, mature plants on a mildly contaminated site, if harvested before the plants die due to phytotoxicity or natural cause, not only survive but may occasionally thrive. The immediate aim is to estimate the effectiveness and limitations of Cd uptake by hyperaccumulators. The eventual goal of this study is to expand the model in spatial and temporal scales, from individual plants to the community scale, and from one harvest interval to several generations. Understanding the interface between physical and biological processes, specifically the uptake and release of contaminants, provides scientists and engineers tools to assess whether phytoremediation is a reasonable strategy for a

  1. Quantitating Antibody Uptake In Vivo: Conditional Dependence on Antigen Expression Levels

    PubMed Central

    Thurber, Greg M.; Weissleder, Ralph

    2010-01-01

    Purpose Antibodies form an important class of cancer therapeutics, and there is intense interest in using them for imaging applications in diagnosis and monitoring of cancer treatment. Despite the expanding body of knowledge describing pharmacokinetic and pharmacodynamic interactions of antibodies in vivo, discrepancies remain over the effect of antigen expression level on tumoral uptake with some reports indicating a relationship between uptake and expression and others showing no correlation. Procedures Using a cell line with high EpCAM expression and moderate EGFR expression, fluorescent antibodies with similar plasma clearance were imaged in vivo. A mathematical model and mouse xenograft experiments were used to describe the effect of antigen expression on uptake of these high affinity antibodies. Results As predicted by the theoretical model, under subsaturating conditions, uptake of the antibodies in such tumors is similar because localization of both probes is limited by delivery from the vasculature. In a separate experiment, when the tumor is saturated, the uptake becomes dependent on the number of available binding sites. In addition, targeting of small micrometastases is shown to be higher than larger vascularized tumors. Conclusions These results are consistent with the prediction that high affinity antibody uptake is dependent on antigen expression levels for saturating doses and delivery for subsaturating doses. It is imperative for any probe to understand whether quantitative uptake is a measure of biomarker expression or transport to the region of interest. The data provide support for a predictive theoretical model of antibody uptake, enabling it to be used as a starting point for the design of more efficacious therapies and timely quantitative imaging probes. PMID:20809210

  2. Expression of the hepatocellular chloride-dependent sulfobromophthalein uptake system in Xenopus laevis oocytes.

    PubMed Central

    Jacquemin, E; Hagenbuch, B; Stieger, B; Wolkoff, A W; Meier, P J

    1991-01-01

    The expression of the basolateral chloride-activated organic anion uptake system of rat hepatocytes has been studied in Xenopus laevis oocytes. Injection of oocytes with rat liver poly(A)+RNA resulted in the functional expression of chloride-dependent sulfobromophthalein (BSP) uptake within 3-5 d. This expressed chloride-dependent BSP uptake system exhibited saturation kinetics (apparent Km approximately 6.2 microM) and efficiently extracted BSP from its binding sites on BSA. Furthermore, the chloride-activated portion of BSP uptake was inhibited by bilirubin (10 microM; inhibition 53%), 4,4'-diisothiocyano-2,2-disulfonic acid stilbene (DIDS, 100 microM; 80%), taurocholate (100 microM; 80%), and cholate (200 microM; 95%). In contrast to results with total rat liver mRNA, injection of mRNA derived from the Na+/bile acid cotransporter cDNA (Hagenbuch, B., B. Stieger, M. Foguet, H. Lübbert, and P. J. Meier. 1991. Proc. Natl. Acad. Sci. USA. In press.) had no effect on BSP uptake into oocytes. Size fractionation of total rat liver mRNA revealed that a 2.0- to 3.5-kb size-class mRNA was sufficient to express the hepatic chloride-dependent BSP uptake system. These data indicate that "expression cloning" in oocytes represents a promising approach to ultimately clone the cDNA coding for the hepatocyte high affinity, chloride-dependent organic anion uptake system. Furthermore, the results confirm that the Na+/bile acid cotransport system does not mediate BSP uptake. PMID:1752967

  3. Significance of incidental focal uptake in prostate on 18-fluoro-2-deoxyglucose positron emission tomography CT images.

    PubMed

    Han, E J; H O, J; Choi, W H; Yoo, I R; Chung, S K

    2010-11-01

    To evaluate the clinical significance of incidental focal prostate fluorodeoxyglucose (FDG) uptake, we reviewed 18-F-FDG positron emission tomography (PET)/CT scans from 2003 to 2007 and selected cases with focal FDG uptake in prostate. Cases of known prostate cancer were excluded. The maximum standardised uptake value (SUV(max)), site (central or peripheral) and pattern (discrete or ill-defined) of FDG uptake, calcification (present or absent) and prostate volume (<30 or ≥30 cc) were recorded. The PET/CT findings were correlated with serum prostate-specific antigen (PSA) levels, imaging studies, clinical follow-up and biopsy. Of a total of 5119 cases, 63 (1.2%) demonstrated focal FDG uptake in prostate. Eight cases were lost to follow-up. Among the 55 cases with follow-up, malignancy was confirmed by biopsy in 3 (5.4%). The three malignant cases had SUV(max) values of 3.3, 3.6 and 2.3, and all were noted in the peripheral portion of prostate; two of these cases had a discrete FDG uptake pattern, none had calcification corresponding to the FDG uptake area and one had a prostatic volume greater than 30 cc. The mean SUV(max) of 52 benign cases was 3.2 ± 1.7 and focal FDG uptake was noted in the peripheral portion in 34 (65%), 20 (38%) cases showed a discrete FDG uptake pattern, 35 (67%) were accompanied by calcification and 32 (62%) had a prostatic volume greater than 30 cc. The majority of cases demonstrating focal FDG uptake in prostate were benign and no PET/CT finding could reliably differentiate benign from malignant lesions; however, when discrete focal FDG uptake without coincidental calcification is seen, particularly in the peripheral zone of the prostate, further clinical evaluation is recommended.

  4. Examination of the mechanism of action of nitrogen monoxide on iron uptake from transferrin.

    PubMed

    Watts, R N; Richardson, D R

    2000-08-01

    Nitrogen monoxide (NO) exerts many of its functions by binding to iron (Fe) in the active sites of a number of key proteins. Previously we have shown that NO produced by NO-generating agents decreased cellular Fe uptake from transferrin (Tf). However, the mechanism of this effect was not elucidated. In this study we examined the possible mechanisms whereby NO could interfere with Fe uptake. Our experiments demonstrate that NO produced by the NO generator S-nitroso-N-acetylpenicillamine was slightly more effective than the Fe chelator deferoxamine at reducing iron 59 uptake from 59Fe-labeled Tf by LMTK- fibroblasts. Other NO generators including S-nitrosoglutathione (GSNO) and spermine-NONOate also decreased 59Fe uptake from 59Fe-labeled Tf. In contrast, precursors of these compounds that do not release NO had no effect. When the RAW264.7 macrophage cell line was activated to produce NO by incubation with lipopolysaccharide or lipopolysaccharide and interferon-gamma, a decrease in 59Fe uptake from 59Fe-labeled Tf was also observed. Experiments with electron paramagnetic resonance spectroscopy and ultraviolet-Vis spectrophotometry demonstrated that NO did not prevent Fe uptake by binding to the Fe-ligating sites of Tf, suggesting that it acted more distally. Because the uptake of Fe is an energy-dependent process, and since NO inhibits mitochondrial respiration, cellular adenosine triphosphate (ATP) was estimated after incubation with GSNO. In the presence of D-glucose (D-G), GSNO reduced ATP levels by 35% as compared with the control, while in the absence of D-G, GSNO reduced ATP by 72%. When the same experiments were performed with D-fructose (D-F), which cannot be efficiently metabolized by fibroblasts, no "rescue" effect was observed on ATP levels. The addition of D-G to GSNO prevented the decrease in 59Fe uptake from 59Fe-labeled Tf while D-F did not, in good correlation with their effects on ATP levels. These results suggest that D-G acts as a salvage

  5. Selenium Uptake and Volatilization by Marine Algae

    NASA Astrophysics Data System (ADS)

    Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.

    2015-04-01

    Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se

  6. Sugar uptake by the solventogenic clostridia.

    PubMed

    Mitchell, Wilfrid J

    2016-02-01

    The acetone-butanol-ethanol fermentation of solventogenic clostridia was operated as a successful, worldwide industrial process during the first half of the twentieth century, but went into decline for economic reasons. The recent resurgence in interest in the fermentation has been due principally to the recognised potential of butanol as a biofuel, and development of reliable molecular tools has encouraged realistic prospects of bacterial strains being engineered to optimise fermentation performance. In order to minimise costs, emphasis is being placed on waste feedstock streams containing a range of fermentable carbohydrates. It is therefore important to develop a detailed understanding of the mechanisms of carbohydrate uptake so that effective engineering strategies can be identified. This review surveys present knowledge of sugar uptake and its control in solventogenic clostridia. The major mechanism of sugar uptake is the PEP-dependent phosphotransferase system (PTS), which both transports and phosphorylates its sugar substrates and plays a central role in metabolic regulation. Clostridial genome sequences have indicated the presence of numerous phosphotransferase systems for uptake of hexose sugars, hexose derivatives and disaccharides. On the other hand, uptake of sugars such as pentoses occurs via non-PTS mechanisms. Progress in characterization of clostridial sugar transporters and manipulation of control mechanisms to optimise sugar fermentation is described.

  7. The Uptake of GABA in Trypanosoma cruzi.

    PubMed

    Galvez Rojas, Robert L; Ahn, Il-Young; Suárez Mantilla, Brian; Sant'Anna, Celso; Pral, Elizabeth Mieko Furusho; Silber, Ariel Mariano

    2015-01-01

    Gamma aminobutyric acid (GABA) is widely known as a neurotransmitter and signal transduction molecule found in vertebrates, plants, and some protozoan organisms. However, the presence of GABA and its role in trypanosomatids is unknown. Here, we report the presence of intracellular GABA and the biochemical characterization of its uptake in Trypanosoma cruzi, the etiological agent of Chagas' disease. Kinetic parameters indicated that GABA is taken up by a single transport system in pathogenic and nonpathogenic forms. Temperature dependence assays showed a profile similar to glutamate transport, but the effect of extracellular cations Na(+) , K(+) , and H(+) on GABA uptake differed, suggesting a different uptake mechanism. In contrast to reports for other amino acid transporters in T. cruzi, GABA uptake was Na(+) dependent and increased with pH, with a maximum activity at pH 8.5. The sensitivity to oligomycin showed that GABA uptake is dependent on ATP synthesis. These data point to a secondary active Na(+) /GABA symporter energized by Na(+) -exporting ATPase. Finally, we show that GABA occurs in the parasite's cytoplasm under normal culture conditions, indicating that it is regularly taken up from the culture medium or synthesized through an still undescribed metabolic pathway.

  8. Effect of insulin on muscle glutamate uptake

    PubMed Central

    Aoki, T. T.; Brennan, M. F.; Müller, W. A.; Moore, F. D.; Cahill, G. F.

    1972-01-01

    For decades, investigators concerned with protein metabolism in man have performed detailed amino acid analyses of human plasma obtained under a wide range of experimental situations. A large body of information has been used to calculated rates of protein synthesis and proteolysis. During the course of an investigation of the effect of intrabrachial artery infusion of insulin (70 μU/min per kg body weight) on glutamate uptake by human forearm muscle, it was discovered that plasma arterio-deep venous glutamate difference analysis failed to document any increase in the uptake of this amino acid, suggesting that insulin had little influence on glutamate uptake by muscle. However, whole blood glutamate analyses, performed on the same blood samples, revealed that (a) the resting muscle uptake of glutamate is smaller than previously reported and (b) insulin is capable of markedly increasing glutamate uptake by muscle from whole blood. Since the hematocrit was obtained on all samples, detailed analyses of the various compartments in which glutamate could be found were performed. It was determined that circulating blood cells have a dynamic role in glutamate transport. These data underscore the need for both whole blood and plasma amino acid analysis in investigations concerned with protein synthesis and/or amino acid flux, for analysis of plasma samples alone could be misleading as illustrated in the present study. Images PMID:5080414

  9. Vimentin mediates uptake of C3 exoenzyme.

    PubMed

    Rohrbeck, Astrid; Schröder, Anke; Hagemann, Sandra; Pich, Andreas; Höltje, Markus; Ahnert-Hilger, Gudrun; Just, Ingo

    2014-01-01

    Clostridium botulinum C3 exoenzyme (C3) selectively inactivates RhoA/B/C GTPases by ADP-ribosylation. Based on this substrate specificity C3 is a well-established tool in cell biology. C3 is taken up by eukaryotic cells although lacking an uptake and translocation domain. Based on different approaches vimentin was identified as membranous C3-interaction partner by mass spectrometry. Vimentin in fact was partly localized at the outer surface of hippocampal HT22 cells and J744A.1 macrophages. Domain analysis identified the rod domain as binding partner of C3. Vimentin was also involved in uptake of C3 as shown by knock down of vimentin in HT22 and J774A.1 cells. The involvement of vimentin in uptake of C3 was further supported by the findings that the vimentin disruptor acrylamide blocked uptake of C3. Vimentin is not only a major organizing element of the intermediate filament network but is also involved in both binding and uptake of C3 exoenzyme. PMID:24967582

  10. The Uptake of GABA in Trypanosoma cruzi.

    PubMed

    Galvez Rojas, Robert L; Ahn, Il-Young; Suárez Mantilla, Brian; Sant'Anna, Celso; Pral, Elizabeth Mieko Furusho; Silber, Ariel Mariano

    2015-01-01

    Gamma aminobutyric acid (GABA) is widely known as a neurotransmitter and signal transduction molecule found in vertebrates, plants, and some protozoan organisms. However, the presence of GABA and its role in trypanosomatids is unknown. Here, we report the presence of intracellular GABA and the biochemical characterization of its uptake in Trypanosoma cruzi, the etiological agent of Chagas' disease. Kinetic parameters indicated that GABA is taken up by a single transport system in pathogenic and nonpathogenic forms. Temperature dependence assays showed a profile similar to glutamate transport, but the effect of extracellular cations Na(+) , K(+) , and H(+) on GABA uptake differed, suggesting a different uptake mechanism. In contrast to reports for other amino acid transporters in T. cruzi, GABA uptake was Na(+) dependent and increased with pH, with a maximum activity at pH 8.5. The sensitivity to oligomycin showed that GABA uptake is dependent on ATP synthesis. These data point to a secondary active Na(+) /GABA symporter energized by Na(+) -exporting ATPase. Finally, we show that GABA occurs in the parasite's cytoplasm under normal culture conditions, indicating that it is regularly taken up from the culture medium or synthesized through an still undescribed metabolic pathway. PMID:25851259

  11. Action on low immunization uptake.

    PubMed

    Azubuike, M C; Ehiri, J E

    1998-01-01

    Despite a number of initiatives and campaigns over the years, immunization coverage in most parts of Nigeria remains low. That low coverage contributes to high morbidity and mortality levels among children. Poor transport, an ineffective cold chain, shortages of trained manpower, and inadequate community support and involvement are some of the factors which explain the underutilization of the immunization service. Aba is a city of approximately 500,000 people in eastern Nigeria in which the majority of inhabitants are traders. Aba's primary health care committee decided that immunization centers should be established in or near main trading areas to accommodate traders who did not want to leave their goods in order to take their children to primary care facilities for immunization. Traders' representatives helped to identify 8 suitable locations for vaccination sites in 3 shopping centers, the local authority provided financial and political support, and the state government gave technical and logistical assistance. The project began in September 1990 and was publicized through the traders' networks, which also helped to mobilize the relevant resources. Since many trading families were reached for the first time at the special centers, immunization coverage improved significantly for the 6 vaccine-preventable childhood diseases. Moreover, the project gave health workers the opportunity to deliver other services and counseling on matters of public health importance.

  12. Increasing uptake of live attenuated influenza vaccine among children in the United States, 2008-2014.

    PubMed

    Rodgers, Loren; Pabst, Laura J; Chaves, Sandra S

    2015-01-01

    The Advisory Committee on Immunization Practices (ACIP) recommends annual influenza vaccination for all persons in the United States aged ≥6 months. On June 25, 2014, ACIP preferentially recommended live attenuated influenza vaccine (LAIV) for healthy children aged 2-8 years. Little is known about national LAIV uptake. To determine uptake of LAIV relative to inactivated influenza vaccine, we analyzed vaccination records from six immunization information system sentinel sites (approximately 10% of US population). LAIV usage increased over time in all sites. Among children 2-8 years of age vaccinated for influenza, exclusive LAIV usage in the collective sentinel site area increased from 20.1% (2008-09 season) to 38.0% (2013-14). During 2013-14, at least half of vaccinated children received LAIV in Minnesota (50.0%) and North Dakota (55.5%). Increasing LAIV usage suggests formulation acceptability, and this preexisting trend offers a favorable context for implementation of ACIP's preferential recommendation.

  13. Uptake of genetic testing for cancer predisposition.

    PubMed Central

    Evans, D G; Maher, E R; Macleod, R; Davies, D R; Craufurd, D

    1997-01-01

    Although there has been much debate about the uptake and effects of predictive testing for common cancers, such as breast and colon cancer, little has been published on the more classical tumour predisposing conditions, such as von Hippel-Lindau disease and familial adenomatous polyposis. Since 1990 the genetics departments in Manchester and Cambridge have had a genetic register for cancer predisposing syndromes and presymptomatic testing for these conditions has been offered once this has become possible. To investigate the factors that might influence uptake of genetic testing in familial cancer syndromes we have reviewed our experience. Demand for predictive testing has generally been high, but men had a lower uptake (77%) than a comparable group of women (93%) (p < 0.01). PMID:9321761

  14. Plant Water Uptake in Drying Soils1

    PubMed Central

    Lobet, Guillaume; Couvreur, Valentin; Meunier, Félicien; Javaux, Mathieu; Draye, Xavier

    2014-01-01

    Over the last decade, investigations on root water uptake have evolved toward a deeper integration of the soil and roots compartment properties, with the goal of improving our understanding of water acquisition from drying soils. This evolution parallels the increasing attention of agronomists to suboptimal crop production environments. Recent results have led to the description of root system architectures that might contribute to deep-water extraction or to water-saving strategies. In addition, the manipulation of root hydraulic properties would provide further opportunities to improve water uptake. However, modeling studies highlight the role of soil hydraulics in the control of water uptake in drying soil and call for integrative soil-plant system approaches. PMID:24515834

  15. Isotopic signatures of production and uptake of H2 by soil

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Popa, M. E.; Batenburg, A. M.; Röckmann, T.

    2015-09-01

    Molecular hydrogen (H2) is the second most abundant reduced trace gas (after methane) in the atmosphere, but its biogeochemical cycle is not well understood. Our study focuses on the soil production and uptake of H2 and the associated isotope effects. Air samples from a grass field and a forest site in the Netherlands were collected using soil chambers. The results show that uptake and emission of H2 occurred simultaneously at all sampling sites, with strongest emission at the grassland sites where clover (N2 fixing legume) was present. The H2 mole fraction and deuterium content were measured in the laboratory to determine the isotopic fractionation factor during H2 soil uptake (αsoil) and the isotopic signature of H2 that is simultaneously emitted from the soil (δDsoil). By considering all net-uptake experiments, an overall fractionation factor for deposition of αsoil = kHD/kHH = 0.945 ± 0.004 (95 % CI) was obtained. The difference in mean αsoil between the forest soil 0.937 ± 0.008 and the grassland 0.951 ± 0.025 is not statistically significant. For two experiments, the removal of soil cover increased the deposition velocity (vd) and αsoil simultaneously, but a general positive correlation between vd and αsoil was not found in this study. When the data are evaluated with a model of simultaneous production and uptake, the isotopic composition of H2 that is emitted at the grassland site is calculated as δDsoil = (-530 ± 40) ‰. This is less deuterium-depleted than what is expected from isotope equilibrium between H2O and H2.

  16. Isotopic signatures of production and uptake of H2 by soil

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Popa, M. E.; Batenburg, A. M.; Röckmann, T.

    2015-11-01

    Molecular hydrogen (H2) is the second most abundant reduced trace gas (after methane) in the atmosphere, but its biogeochemical cycle is not well understood. Our study focuses on the soil production and uptake of H2 and the associated isotope effects. Air samples from a grass field and a forest site in the Netherlands were collected using soil chambers. The results show that uptake and emission of H2 occurred simultaneously at all sampling sites, with strongest emission at the grassland sites where clover (N2 fixing legume) was present. The H2 mole fraction and deuterium content were measured in the laboratory to determine the isotopic fractionation factor during H2 soil uptake (αsoil) and the isotopic signature of H2 that is simultaneously emitted from the soil (δDsoil). By considering all net-uptake experiments, an overall fractionation factor for deposition of αsoil = kHD / kHH = 0.945 ± 0.004 (95 % CI) was obtained. The difference in mean αsoil between the forest soil 0.937 ± 0.008 and the grassland 0.951 ± 0.026 is not statistically significant. For two experiments, the removal of soil cover increased the deposition velocity (vd) and αsoil simultaneously, but a general positive correlation between vd and αsoil was not found in this study. When the data are evaluated with a model of simultaneous production and uptake, the isotopic composition of H2 that is emitted at the grassland site is calculated as δDsoil = (-530 ± 40) ‰. This is less deuterium depleted than what is expected from isotope equilibrium between H2O and H2.

  17. Characterization of a Dipartite Iron Uptake System from Uropathogenic Escherichia coli Strain F11*

    PubMed Central

    Koch, Doreen; Chan, Anson C. K.; Murphy, Michael E. P.; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H.

    2011-01-01

    In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His44, Met90, His97, and His127, and CuB, a second degenerate octahedral geometry with the addition of Glu46. The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein. PMID:21596746

  18. Potassium Uptake Modulates Staphylococcus aureus Metabolism

    PubMed Central

    Gries, Casey M.; Sadykov, Marat R.; Bulock, Logan L.; Chaudhari, Sujata S.; Thomas, Vinai C.; Bose, Jeffrey L.

    2016-01-01

    ABSTRACT As a leading cause of community-associated and nosocomial infections, Staphylococcus aureus requires sophisticated mechanisms that function to maintain cellular homeostasis in response to its exposure to changing environmental conditions. The adaptation to stress and maintenance of homeostasis depend largely on membrane activity, including supporting electrochemical gradients and synthesis of ATP. This is largely achieved through potassium (K+) transport, which plays an essential role in maintaining chemiosmotic homeostasis, affects antimicrobial resistance, and contributes to fitness in vivo. Here, we report that S. aureus Ktr-mediated K+ uptake is necessary for maintaining cytoplasmic pH and the establishment of a proton motive force. Metabolite analyses revealed that K+ deficiency affects both metabolic and energy states of S. aureus by impairing oxidative phosphorylation and directing carbon flux toward substrate-level phosphorylation. Taken together, these results underline the importance of K+ uptake in maintaining essential components of S. aureus metabolism. IMPORTANCE Previous studies describing mechanisms for K+ uptake in S. aureus revealed that the Ktr-mediated K+ transport system was required for normal growth under alkaline conditions but not under neutral or acidic conditions. This work focuses on the effect of K+ uptake on S. aureus metabolism, including intracellular pH and carbon flux, and is the first to utilize a pH-dependent green fluorescent protein (GFP) to measure S. aureus cytoplasmic pH. These studies highlight the role of K+ uptake in supporting proton efflux under alkaline conditions and uncover a critical role for K+ uptake in establishing efficient carbon utilization. PMID:27340697

  19. Potassium Uptake Modulates Staphylococcus aureus Metabolism.

    PubMed

    Gries, Casey M; Sadykov, Marat R; Bulock, Logan L; Chaudhari, Sujata S; Thomas, Vinai C; Bose, Jeffrey L; Bayles, Kenneth W

    2016-01-01

    As a leading cause of community-associated and nosocomial infections, Staphylococcus aureus requires sophisticated mechanisms that function to maintain cellular homeostasis in response to its exposure to changing environmental conditions. The adaptation to stress and maintenance of homeostasis depend largely on membrane activity, including supporting electrochemical gradients and synthesis of ATP. This is largely achieved through potassium (K(+)) transport, which plays an essential role in maintaining chemiosmotic homeostasis, affects antimicrobial resistance, and contributes to fitness in vivo. Here, we report that S. aureus Ktr-mediated K(+) uptake is necessary for maintaining cytoplasmic pH and the establishment of a proton motive force. Metabolite analyses revealed that K(+) deficiency affects both metabolic and energy states of S. aureus by impairing oxidative phosphorylation and directing carbon flux toward substrate-level phosphorylation. Taken together, these results underline the importance of K(+) uptake in maintaining essential components of S. aureus metabolism. IMPORTANCE Previous studies describing mechanisms for K(+) uptake in S. aureus revealed that the Ktr-mediated K(+) transport system was required for normal growth under alkaline conditions but not under neutral or acidic conditions. This work focuses on the effect of K(+) uptake on S. aureus metabolism, including intracellular pH and carbon flux, and is the first to utilize a pH-dependent green fluorescent protein (GFP) to measure S. aureus cytoplasmic pH. These studies highlight the role of K(+) uptake in supporting proton efflux under alkaline conditions and uncover a critical role for K(+) uptake in establishing efficient carbon utilization. PMID:27340697

  20. Enantioselective cellular uptake of chiral semiconductor nanocrystals

    NASA Astrophysics Data System (ADS)

    Martynenko, I. V.; Kuznetsova, V. A.; Litvinov, I. K.; Orlova, A. O.; Maslov, V. G.; Fedorov, A. V.; Dubavik, A.; Purcell-Milton, F.; Gun'ko, Yu K.; Baranov, A. V.

    2016-02-01

    The influence of the chirality of semiconductor nanocrystals, CdSe/ZnS quantum dots (QDs) capped with L- and D-cysteine, on the efficiency of their uptake by living Ehrlich Ascite carcinoma cells is studied by spectral- and time-resolved fluorescence microspectroscopy. We report an evident enantioselective process where cellular uptake of the L-Cys QDs is almost twice as effective as that of the D-Cys QDs. This finding paves the way for the creation of novel approaches to control the biological properties and behavior of nanomaterials in living cells.

  1. Cadmium uptake and resistance among selected bacteria

    SciTech Connect

    Burke, B.E.

    1987-01-01

    The purpose of this research was to determine the relationship between Cd resistance and Cd uptake by lake sediment bacteria. For the Gram positive and gram negative sediment bacteria that were tested, the relationship between resistance and Cd uptake varied and was dependent on the isolate under consideration. Results of this study indicated that bacterial communities in lake sediments may influence the concentration and availability of Cd in sediments and the water column. In addition, results of this study did not support the theory that the genes encoding for Cd resistance are usually carried on antibiotic resistance plasmids.

  2. Tracking the diurnal signal of plant water uptake through the hydrologic system

    NASA Astrophysics Data System (ADS)

    Blume, Theresa; Hassler, Sibylle; Heidbüchel, Ingo; Weiler, Markus; Simard, Sonia; Güntner, Andreas; Heinrich, Ingo

    2015-04-01

    Plant water uptake during summer is characterized by strong diurnal fluctuations. As a result a diurnal sink term is imposed on catchment storage, affecting the unsaturated zone, sometimes the saturated zone and even streamflow. Detecting this signal and understanding its propagation through the hydrological system may help to better quantify eco-hydrological connectivity. The extent and strength of the propagation of this signal from plant to soil to ground- and stream water was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographies and types of vegetation. Vegetation types include grassland, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture profiles, matrix potential, piezometers and sapflow sensors (as proxy for plant water uptake) as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. Signal strength (amplitude of diurnal fluctuations) can thus be traced through the system and gives an indication of the physical sphere of influence of plant water uptake i.e. the "eco-hydro-connectivity". Temporal dynamics of signal strength furthermore suggest a shifting spatial distribution of root water uptake with time. The analysis of time lags (or phase shifts) between daily fluctuations in temperature, radiation, sapflow, soil water, groundwater and streamflow gives further insights into the processes driving and propagating these signals and inter-site comparison allows for the investigation of local controls.

  3. Contributions of Atmospheric CO and Hydrogen Uptake to Microbial Dynamics on Recent Hawaiian Volcanic Deposits†

    PubMed Central

    King, Gary M.

    2003-01-01

    A series of sites were established on Hawaiian volcanic deposits ranging from about 18 to 300 years old. Three sites occurred in areas that supported tropical rain forests; the remaining sites were in areas that supported little or no plant growth. Sites >26 years old consumed atmospheric CO and hydrogen at rates ranging from about 0.2 to 5 mg of CO m−2 day−1 and 0.1 to 4 mg of H2 m−2 day−1, respectively. Respiration, measured as CO2 production, for a subset of the sites ranged from about 40 to >1,400 mg of CO2 m−2 day−1. CO and H2 accounted for about 13 to 25% of reducing equivalent flow for all but a forested site, where neither substrate appeared significant. Based on responses to chloroform fumigation, hydrogen utilization appeared largely due to microbial uptake. In contrast to results for CO and hydrogen, methane uptake occurred consistently only at the forest site. Increasing deposit age was generally accompanied by increasing concentrations of organic matter and microbial biomass, measured as phospholipid phosphate. Exoenzymatic activities (acid and alkaline phosphatases and α- and β-glucosidases) were positively correlated with deposit age in spite of considerable variability within sites. The diversity of substrates utilized in Biolog Ecoplate assays also increased with deposit age, possibly reflecting changes in microbial community complexity. PMID:12839783

  4. Contributions of atmospheric CO and hydrogen uptake to microbial dynamics on recent Hawaiian volcanic deposits.

    PubMed

    King, Gary M

    2003-07-01

    A series of sites were established on Hawaiian volcanic deposits ranging from about 18 to 300 years old. Three sites occurred in areas that supported tropical rain forests; the remaining sites were in areas that supported little or no plant growth. Sites >26 years old consumed atmospheric CO and hydrogen at rates ranging from about 0.2 to 5 mg of CO m(-2) day(-1) and 0.1 to 4 mg of H(2) m(-2) day(-1), respectively. Respiration, measured as CO(2) production, for a subset of the sites ranged from about 40 to >1,400 mg of CO(2) m(-2) day(-1). CO and H(2) accounted for about 13 to 25% of reducing equivalent flow for all but a forested site, where neither substrate appeared significant. Based on responses to chloroform fumigation, hydrogen utilization appeared largely due to microbial uptake. In contrast to results for CO and hydrogen, methane uptake occurred consistently only at the forest site. Increasing deposit age was generally accompanied by increasing concentrations of organic matter and microbial biomass, measured as phospholipid phosphate. Exoenzymatic activities (acid and alkaline phosphatases and alpha- and beta-glucosidases) were positively correlated with deposit age in spite of considerable variability within sites. The diversity of substrates utilized in Biolog Ecoplate assays also increased with deposit age, possibly reflecting changes in microbial community complexity.

  5. Extrapulmonary sites of radiogallium accumulation in sarcoidosis

    SciTech Connect

    Sulavik, S.B.; Palestro, C.J.; Spencer, R.P.; Swyer, A.J.; Goldsmith, S.J.; Tierstein, A.S. )

    1990-12-01

    In an effort to detect extrapulmonary sites of radiogallium accumulation in cases of sarcoidosis, 145 separate Ga-67 citrate studies of 114 patients with biopsy-proven sarcoidosis were examined. The most characteristic extrapulmonary radiogallium uptake pattern was the panda sign in 47 patients (41%). The most common site of prominent extrapulmonary radiogallium uptake was the lacrimal glands in 101 patients (88%). Second most common was activity in one or more superficial lymph node regions such as the cervical, axillary, femoral, or inguinal in 19 patients (17%). Other extrapulmonary sites included breast uptake in 6 out of 80 women (8%), prominent splenic and nasal uptake in 9 (8%) patients, periportal accumulation in 7 (6%), and cutaneous/subcutaneous activity in 4 (4%). Because many of these individuals were receiving corticosteroids, the natural (untreated) prevalence of extrapulmonary findings may be even higher. Although the sensitivity and specificity of extrapulmonary radiogallium accumulation has still to be determined, many of the sites may be accessible to biopsy both for diagnostic purposes and to follow the effects of medications. It is therefore suggested that whole-body imaging be performed when radiogallium is administered to patients with suspected or known sarcoidosis.

  6. Uptake, translocation, and accumulation of polycyclic aromatic hydrocarbons in vegetation

    SciTech Connect

    Walton, B.T. ); Hoylman, A.M. )

    1992-12-01

    A review of the scientific literature was conducted to determine the potential for plants to take up polycyclic aromatic hydrocarbons (PAHs) from soils and the possibility of PAH movement from soils into vegetation at waste disposal sites associated with manufactured gas plants (MGP). Studies published since 1983 are considered in conjunction with previous publications and literature reviews on PAH uptake by vegetation. These studies indicate that the extent to which sorption to roots occurs is likely to be influenced by species-specific properties of the plant, physicochemical properties of each PAH, soil properties, and biodegradation rates of the PAHs in soil. PAHs containing five or more rings may sorb to plant roots but are not expected to be translocated to foliage in other than trace quantities. Uptake of naphthalene, anthracene, and benzo[a]anthracene by roots has been reported in the literature. In addition, eight PAHs of three and four rings (acenapthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, and chrysene) were isolated from leaves and roots of four plant species collected near a coal tar disposal trench in eastern Tennessee. A total concentration of 5519 ng/g was observed for the eight PAHs in roots of lamb's quarters. Coal tar, in soil, was implicated as the source of PAHs in the four plant species.

  7. Classification of Physiological 18F-fluorodeoxyglucose Uptake in the Large Intestine: a Preliminary Study.

    PubMed

    Yasuda, Seiei; Kobayashi, Katsuyuki; Ono, Masao; Miyatake, Yoshiko; Miyauchi, Mizuho; Kato, Tatsuya; Tanaka, Tatsuro; Ito, Masayoshi; Yamamoto, Nobuhiko

    2014-09-20

    Varying degrees of physiological uptake of 18F-fluorodeoxyglucose (FDG) are often noted in the large intestine and can be problematic when interpreting positron emission tomography (PET) images. In relation to colorectal tumor detection with FDG PET, we tentatively classified physiological FDG uptake in the large intestine according to its patterns and intensity. Subjects were 144 asymptomatic individuals (109 men, 35 women; mean age 57.5 ± 10.1 years) in our cancer screening program who underwent total colonoscopy within 24 days of FDG PET study and showed no evidence of colonic lesions on colonoscopy. Distinct FDG uptake on FDG PET images was classified into four types: focal, defined as distinctly nodular and visible on at least 4 axial; localized, 2 to 8 cm with SUVmean ≥ 4; diffuse, > 8 cm with SUVmean ≥ 4; and mixed, of more than one type. SUVmeans were examined by placing multiple circular regions of interest of 1 cm in diameter on the axial images. We found 21 distinct FDG uptakes matching our criteria in 20 of 144 subjects (13.9%): focal (n = 4), localized (n = 1), diffuse (n = 14), and mixed (n = 1; focal and diffuse). With regard to colorectal tumor detection, 6 subjects (4.2%) with focal or localized type of uptake were considered at risk of false-positive tumor identification, and 15 subjects (10.4%) with diffuse type of uptake were considered at risk of their tumors being missed at the site of FDG uptake. To confirm the feasibility of our criteria, this classification should be tested with a larger number of subjects.

  8. Characterization of taurine binding, uptake, and release in the rat hypothalamus

    SciTech Connect

    Hanretta, A.T.

    1985-01-01

    The neurotransmitter criteria of specific receptors, inactivation, and release were experimentally examined for taurine in the hypothalamus. Specific membrane binding and synaptosomal uptake of taurine both displayed high affinity and low affinity systems. The neurotransmitter criterion of release was studied in superfused synaptosomes. Exposure of synaptosomes which had been preloaded with a concentration of (/sup 3/H)taurine in the high affinity uptake range (1.5 ..mu..M) to either 56 mM K/sup +/ or 100 ..mu..M veratridine evoked a Ca/sup 2 +/-independent release. Exposure of synaptosomes which had been preloaded with a concentration of (/sup 3/H)taurine in the low affinity uptake range (2 mM) to 56 mM K/sup +/ induced a Ca/sup 2 +/-independent release, whereas 100 /sup +/M veratridine did not, either in the presence or absence of Ca/sup 2 +/. Based on these results, as well as other observations, a model is proposed in which the high affinity uptake system is located on neuronal membranes and the low affinity uptake system is located on glial membranes. The mechanisms of binding, uptake, and release in relation to the cellular location of each are discussed. We conclude that the neurotransmitter criterion of activation by re-uptake is satisfied for taurine in the hypothalamus. However, the failure to demonstrate both a specific taurine receptor site and a Ca/sup 2 +/-dependent evoked release, necessitates that we conclude that taurine appears not to function as a hypothalamic neurotransmitter, at least not in the classical sense.

  9. Inhibition of Phosphate Uptake in Corn Roots by Aluminum-Fluoride Complexes1

    PubMed Central

    Façanha, Arnoldo Rocha; Okorokova-Façanha, Anna L.

    2002-01-01

    F forms stable complexes with Al at conditions found in the soil. Fluoroaluminate complexes (AlFx) have been widely described as effective analogs of inorganic phosphate (Pi) in Pi-binding sites of several proteins. In this work, we explored the possibility that the phytotoxicity of AlFx reflects their activity as Pi analogs. For this purpose, 32P-labeled phosphate uptake by excised roots and plasma membrane H+-ATPase activity were investigated in an Al-tolerant variety of maize (Zea mays L. var. dwarf hybrid), either treated or not with AlFx. In vitro, AlFx competitively inhibited the rate of root phosphate uptake as well as the H+-ATPase activity. Conversely, pretreatment of seedlings with AlFx in vivo promoted no effect on the H+-ATPase activity, whereas a biphasic effect on Pi uptake by roots was observed. Although the initial rate of phosphate uptake by roots was inhibited by AlFx pretreatment, this situation changed over the following minutes as the rate of uptake increased and a pronounced stimulation in subsequent 32Pi uptake was observed. This kinetic behavior suggests a reversible and competitive inhibition of the phosphate transporter by fluoroaluminates. The stimulation of root 32Pi uptake induced by AlFx pretreatment was tentatively interpreted as a phosphate starvation response. This report places AlF3 and AlF4− among Al-phytotoxic species and suggests a mechanism of action where the accumulation of Pi-mimicking fluoroaluminates in the soil may affect the phosphate absorption by plants. The biochemical, physiological, and environmental significance of these findings is discussed. PMID:12177489

  10. The gut wall provides an effective barrier against nanoparticle uptake

    PubMed Central

    Sinnecker, Heike; Krause, Thorsten; Koelling, Sabine; Lautenschläger, Ingmar

    2014-01-01

    Summary Background: The omnipresence of nanoparticles (NPs) in numerous goods has led to a constant risk of exposure and inadvertent uptake for humans. This situation calls for thorough investigation of the consequences of NP intake. As the vast mucosa of the human gastrointestinal tract represents an attractive site of entry, we wanted to take a look on the fate that ingested NPs suffer in the gut. As a model to investigate NP uptake we used the isolated perfused rat small intestine. Differently sized fluorescent latex particles were used as exemplary anthropogenic NPs. Results: The particles were administered as bolus into the isolated intestine, and samples from the luminal, vascular and lymphatic compartments were collected over time. NP amounts in the different fluids were determined by fluorescence measurements. No particles could be detected in the vascular and lymphatic system. By contrast a major amount of NPs was found in luminal samples. Yet, a substantial share of particles could not be recovered in the fluid fractions, indicating a sink function of the intestinal tissue for NPs. A histological examination of the gut revealed that virtually no particles adhered to the epithelium or resided in the tissue, the bulk of particles seemed to be trapped in the mucus lining the gut tube. When this mucus was dissolved and removed from the gut almost the entire amount of particles missing could be recovered: over 95% of the given NPs were present in the two fractions, the luminal samples and the dissolved mucus. To foster NP uptake via an extended interaction time with the epithelium, the intestinal peristalsis was decelerated and the duration of the experiment was prolonged. Even under those conditions, no particle fluorescence was detected in the vascular and lymphatic samples. Conclusion: We could show that after intestinal exposure with a large dose of NPs the vast majority of NPs did obviously not come into contact with the epithelium but was either directly

  11. The Relationship Between Uptake and Questioning.

    ERIC Educational Resources Information Center

    Kebede, S.

    1999-01-01

    Considers whether it is possible to account for the phenomenon of uptake by looking at some of the discoursal features of the interactive work that goes on between an instructor and his students in biology lessons in the context of nonnative English-speaking instructors working with nonnative English-speaking students in a tertiary-level…

  12. Routes and mechanisms of extracellular vesicle uptake

    PubMed Central

    Mulcahy, Laura Ann; Pink, Ryan Charles; Carter, David Raul Francisco

    2014-01-01

    Extracellular vesicles (EVs) are small vesicles released by donor cells that can be taken up by recipient cells. Despite their discovery decades ago, it has only recently become apparent that EVs play an important role in cell-to-cell communication. EVs can carry a range of nucleic acids and proteins which can have a significant impact on the phenotype of the recipient. For this phenotypic effect to occur, EVs need to fuse with target cell membranes, either directly with the plasma membrane or with the endosomal membrane after endocytic uptake. EVs are of therapeutic interest because they are deregulated in diseases such as cancer and they could be harnessed to deliver drugs to target cells. It is therefore important to understand the molecular mechanisms by which EVs are taken up into cells. This comprehensive review summarizes current knowledge of EV uptake mechanisms. Cells appear to take up EVs by a variety of endocytic pathways, including clathrin-dependent endocytosis, and clathrin-independent pathways such as caveolin-mediated uptake, macropinocytosis, phagocytosis, and lipid raft–mediated internalization. Indeed, it seems likely that a heterogeneous population of EVs may gain entry into a cell via more than one route. The uptake mechanism used by a given EV may depend on proteins and glycoproteins found on the surface of both the vesicle and the target cell. Further research is needed to understand the precise rules that underpin EV entry into cells. PMID:25143819

  13. Thiamin function, metabolism, uptake, and transport.

    PubMed

    Manzetti, Sergio; Zhang, Jin; van der Spoel, David

    2014-02-11

    Vitamins are crucial components in the diet of animals and many other living organisms. One of these essential nutrients, thiamin, is known to be involved in several cell functions, including energy metabolism and the degradation of sugars and carbon skeletons. Other roles that are connected to this vitamin are neuronal communication, immune system activation, signaling and maintenance processes in cells and tissues, and cell-membrane dynamics. Because of the key functions of thiamin, uptake and transport through the body are crucial. Its uptake route is relatively complex, encompassing a variety of protein families, including the solute carrier anion transporters, the alkaline phosphatase transport system, and the human extraneuronal monoamine transporter family, some of which are multispecific proteins. There are two known structures of protein (subunits) involved in thiamin uptake in prokaryotes. Binding of thiamin to these proteins is strongly guided by electrostatic interactions. The lack of structural information about thiamin binding proteins for higher organisms remains a bottleneck for understanding the uptake process of thiamin in atomic detail. This review includes recent data on thiamin metabolism, related deficiencies and pathologies, and the latest findings on thiamin binding transporters.

  14. Direct uptake of soil nitrogen by mosses.

    PubMed

    Ayres, Edward; van der Wal, René; Sommerkorn, Martin; Bardgett, Richard D

    2006-06-22

    Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques (15N). Both species exhibited increased concentrations of shoot 15N when exposed to either soil- or wet deposition-derived 15N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated.

  15. Implications of abnormal right ventricular thallium uptake in acute myocardial infarction

    SciTech Connect

    Nestico, P.F.; Hakki, A.H.; Felsher, J.; Heo, J.; Iskandrian, A.S.

    1986-08-01

    The correlates of abnormal right ventricular (RV) thallium uptake were examined in 116 patients with documented acute myocardial infarction (AMI) who underwent predischarge thallium-201 scintigraphy at rest, radionuclide angiography and 24-hour ambulatory electrocardiography. The patients were separated into 2 groups: patients group 1 (n = 31) had increased RV thallium uptake and those in group 2 (n = 85) had no such uptake. The 2 groups were comparable in age, type and site of AMI, peak creatine kinase level, systolic blood pressure and heart rate. However, compared with group 2, group 1 had a lower mean left ventricular (LV) ejection fraction (33 +/- 15% vs 39 +/- 14%, p less than 0.05), higher prevalence of increased lung thallium uptake (45% vs 22%, p less than 0.02), more extensive LV perfusion defects (4.4 +/- 2.9 vs 3.0 +/- 3.0 segments, p less than 0.03) and more complex ventricular arrhythmias (55% vs 35%, p less than 0.05). At a mean follow-up of 6 months, 17 patients (8 in group 1 and 9 in group 2) died from cardiac causes. Actuarial life-table analysis showed that the survival rate was better in group 2 than in group 1 (Mantel-Cox statistics = 4.62, p = 0.03). Thus, patients with AMI and abnormal RV thallium uptake have worse LV function, more complex ventricular arrhythmias and worse prognosis.

  16. Hardwood seeding root and nutrient parameters for a model of nutrient uptake.

    PubMed

    Kelly, J M; Scarbrough, J D; Mays, P A

    2001-01-01

    Use of mechanistic models is an increasingly accepted way to evaluate complex processes. The Barber-Cushman model provides a means to simulate nutrient uptake once information on root system characteristics, nutrient uptake, and soil nutrient supply are developed. Objectives of this study were to determine during a growing season: (i) root growth for 1-yr-old black cherry (Prunus serotina Ehrh.), northern red oak (Quercus rubra L.), and red maple (Acer rubrum L.) seedlings; (ii) net plant increase in N, P, K, Ca, and Mg; (iii) soil solution and solid phase nutrient concentrations; and (iv) the influence of root growth and soil nutrient supply changes on nutrient uptake using the Barber-Cushman model. Seedlings were grown in pots containing A horizon soil from two forest sites. Measurements were made on five occasions during the growing season. Root growth averaged 41.5 cm d-1 for red maple compared with 28.0 and 16.7 cm d-1 for cherry and oak, respectively. Seventy-five percent of root growth occurred at the end of the growing season. Total plant N showed the greatest change (25-58%) due to soil source. Model simulations underestimated observed uptake by 31 to 99%. A clear relationship between soil solution nutrient concentration and plant uptake, an important assumption of the model, was not observed. Results indicate care will need to be exercised in the development and use of root growth and nutrient supply values in mechanistic models. PMID:11285903

  17. DOC:NO3- ratios and NO3- uptake in forested headwater streams

    NASA Astrophysics Data System (ADS)

    Rodríguez-Cardona, Bianca; Wymore, Adam S.; McDowell, William H.

    2016-01-01

    The underlying mechanisms driving the coupled interactions between inorganic nitrogen uptake and dissolved organic matter are not well understood, particularly in surface waters. To determine the relationship between dissolved organic carbon (DOC) quantity and nitrate (NO3-) uptake kinetics in streams, we performed a series of NO3- Tracer Additions for Spiraling Curve Characterization experiments in four streams within the Lamprey River Watershed, New Hampshire, across a range in background DOC concentrations (1-8 mg C/L). Experiments were performed throughout the 2013 and 2014 growing seasons. Across streams and experimental dates, ambient uptake velocity (Vf) correlated positively with increasing DOC concentrations and DOC:NO3- ratios but was only weakly negatively associated with NO3- concentrations. Ambient NO3- Vf was unrelated to pH, light, temperature, dissolved oxygen, and Specific Ultraviolet Absorbance at 254 nm. Although there were general tendencies across the entire Lamprey River Watershed, individual sites behaved differently in their uptake kinetics. NO3- uptake dynamics in the Lamprey River Watershed are most strongly influenced by DOC concentrations rather than NO3- concentrations or physicochemical parameters, which have been identified as regional- to continental-scale drivers in previous research. Understanding the fundamental relationships between dissolved organic matter and inorganic nutrients will be important as global and climatic changes influence the delivery and production of DOC and NO3- in aquatic ecosystems.

  18. Effects of pH on uranium uptake and oxidative stress responses induced in Arabidopsis thaliana.

    PubMed

    Saenen, Eline; Horemans, Nele; Vanhoudt, Nathalie; Vandenhove, Hildegarde; Biermans, Geert; Van Hees, May; Wannijn, Jean; Vangronsveld, Jaco; Cuypers, Ann

    2013-09-01

    Uranium (U) causes oxidative stress in Arabidopsis thaliana plants grown at pH 5.5. However, U speciation and its toxicity strongly depend on environmental parameters, for example pH. It is unknown how different U species determine U uptake and translocation within plants and how they might affect the oxidative defense mechanisms of these plants. The present study analyzed U uptake and oxidative stress-related responses in A. thaliana (Columbia ecotype) under contrasted U chemical speciation conditions. The 18-d-old seedlings were exposed for 3 d to 25 µM U in a nutrient solution of which the pH was adjusted to 4.5, 5.5, 6.5, or 7.5. Results indicate that there is a different rate of U uptake and translocation at the different pHs, with high uptake and low translocation at low pH and lower uptake but higher translocation at high pH. After U exposure, an increased glutathione reductase activity and total glutathione concentration were observed in U-exposed roots, pointing toward an important role for glutathione in the root defense system against U either by chelation or by antioxidative defense mechanisms. In leaves, antioxidative defense mechanisms were activated on U exposure, indicated by increased superoxide dismutase and catalase activity. As it seems that U toxicity is influenced by pH, it is important to consider site-specific characteristics when making U risk assessments. PMID:23737149

  19. Uptake rates of thorium progeny in a semiarid environment.

    PubMed

    McClellan, Yvonne; August, Robert; Gosz, James; Gann, Steve; Parmenter, Robert; Nelson, Martin; Harper, Mark

    2003-01-01

    The release rates and transformation processes that influence the mobility, biological uptake, and transfer of radionuclides are essential to the assessment of the health effects in the food chain and ecosystem. This study examined concentrations of 222Th in both soil and vegetation at a closed military training site, Kirtland Air Force Base (KAFB), New Mexico. Brazilian sludge was intentionally introduced into the topsoil in the early 1960s to simulate nuclear weapon accidents. Soil (60) and vegetation (120) samples were collected from 1996 to 2000 and analyzed for radionuclides and progeny. High-resolution gamma-ray spectroscopy was used to determine radionuclide activities. The results indicate that the thorium progeny were the predominant contaminant in soil and vegetation. Concentration ratios (CRs) were calculated based on actinium levels. PMID:14535318

  20. Nutrient Uptake Kinetics in Two Virginia Estuaries

    NASA Astrophysics Data System (ADS)

    Henry, A.; Mulholland, M. R.; Bernhardt, P.; Watson, A. M.; Dias, R. F.

    2002-12-01

    Recently, there has been an increase in the occurrence and geographical range of blooms of the brown tide pelagophyte Aureococcus anophagefferens in coastal areas along the east coast of the USA. Brown tide blooms occur when concentrations of inorganic nutrients are low or at the limit of analytical detection and these organisms have been shown to use organic nitrogen for growth. Indeed, it has been suggested that A. anophagefferens, along with a variety of other species that form harmful algal blooms, have a preference for organic nitrogen and because organic nitrogen compounds also have carbon, it is thought that many bloom species may supplement photosynthetic carbon fixation with uptake of organic carbon. In order to better understand the nutritional preferences of bloom organisms, we investigated uptake kinetics for inorganic and organic nutrients in two Virginia waterways where harmful algal blooms frequently occur; the Rappahannock River, a Chesapeake Bay tributary that experiences blooms of dinoflagellates, and Chincoteague Bay, a coastal bay where there are seasonal brown tide blooms. We used stable isotopes (15N and 13C) to measure uptake kinetics for NH4+, urea, two amino acids, a dipeptide and glucose. During the Chincoteague Bay study, there was a bloom of A. anophagefferens (> 1,000,000 cells/ml), however, no blooms were encountered during the Rappahannock Study. Results suggest that brown tide bloom populations had higher affinities and uptake capacities for NH4+ and dipeptides and lower affinities and uptake capacities for urea and the two amino acids. In addition, it appeared that the organic substrates were used primarily as N sources.

  1. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    NASA Astrophysics Data System (ADS)

    Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; Berkelhammer, Max; Desai, Ankur R.; Campbell, J. Elliott

    2016-03-01

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil-COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States found soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, > 800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. While COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.

  2. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    DOE PAGES

    Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; Berkelhammer, Max; Desai, Ankur R.; Campbell, J. Elliott

    2016-03-21

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States found soilmore » COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, >800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. Furthermore, while COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.« less

  3. Investigating phosphorus uptake in anoxic and sulfidic surface sediments with 33P radiotracer experiments

    NASA Astrophysics Data System (ADS)

    Dijkstra, Nikki; Kraal, Peter; Gonzalez, Santiago; Slomp, Caroline

    2016-04-01

    Phosphorus (P) is a key nutrient for marine organisms. Enhanced P availability in the water column can fuel algal blooms and the development of bottom water anoxia. Recently, it was suggested that micro-organisms in sediments overlain by anoxic and sulfidic bottom waters might take up dissolved P and form Fe(II)-P minerals, thereby enhancing P removal. In this study, we investigated the uptake of P in surface sediments with 33P radiotracer experiments. The sediments were recovered from the anoxic and sulfidic deep basin of the Black Sea and, for comparison, from the adjacent oxic shelf. Results suggest a very fast sedimentary uptake of 33P at all sites but in particular for sediments from the oxic shelf. At all sites, most 33P was sequestered in the citrate-dithionite-bicarbonate-(CDB)-extractable sediment P fraction. No significant differences with abiotic controls were observed, implying that micro-organisms were not directly involved in the P uptake. Whereas 33P uptake by the oxic shelf sediment was likely controlled by sorption of 33P to iron(Fe)-(oxyhydr)oxides, the nature of the CDB-extractable P fraction in the deep basin sediments remains unclear. We discuss whether authigenic formation of Fe(II)-P minerals or fast adsorption of P to calcites may explain our findings.

  4. Effects of ammonium and nitrate on nutrient uptake and activity of nitrogen assimilating enzymes in western hemlock

    SciTech Connect

    Knoepp, J.D.; Turner, D.P.; Tingey, D.T.

    1993-01-01

    Western hemlock seedlings were grown in nutrient solutions with ammonium, nitrate or ammonium plus nitrate as nitrogen sources. The objectives were to examine (1) possible selectivity for ammonium or nitrate as an N source, (2) the maintenance of charge balance during ammonium and nitrate uptake, and (3) the activity of the nitrogen assimilating enzymes, nitrate reductase, glutamine synthetase, and glutamine dehydrogenase, in relation to the uptake of different nitrogen sources. The uptake studies revealed that western hemlock takes up ammonium faster than nitrate and that ammonium partially inhibits nitrate uptake. Nitrate reductase activity varied with nitrate availability in root tissue, but showed no response in needles, indicating that most nitrate is reduced in the roots. Results indicate that western hemlock may be adapted to sites where NH(4+) is the predominate N source.

  5. Imipramine treatment differentially affects platelet /sup 3/H-imipramine binding and serotonin uptake in depressed patients

    SciTech Connect

    Suranyi-Cadotte, B.E.; Quirion, R.; Nair, N.P.V.; Lafaille, F.; Schwartz, G.

    1985-02-25

    Uptake of serotonin and /sup 3/H-imipramine binding in platelets of depressed patients were investigated simultaneously with changes in clinical state. Both V/sub max/ for serotonin uptake and B/sub max/ for /sup 3/H-imipramine binding were significantly lower in unmedicated depressed patients with respect to normal subjects. Successful treatment with imipramine led to a significant increase in B/sub max/ for /sup 3/H-imipramine binding, without significant change in V/sub max/ for serotonin uptake. B/sub max/ values increased to the normal range following complete, rather than partial clinical improvement. These data indicate that successful antidepressant treatment may increase the density of /sup 3/H-imipramine binding sites on platelets by a process which is independent of the uptake of serotonin. 29 references, 1 table.

  6. Comparing Measures of Fine Root Uptake by Mature Trees: Applications for Determining the Potential Impacts of Climate Change-Induced Soil Freezing on Nutrient Uptake by Sugar Maple and Red Spruce

    NASA Astrophysics Data System (ADS)

    Socci, A. M.; Templer, P. H.

    2008-12-01

    and the peak growing seasons. Rates of nutrient uptake by intact roots were significantly greater than rates of uptake by excised roots for both sugar maple and red spruce. Despite this difference, the patterns of NH4+ uptake compared to NO3- uptake were consistent across both methods. These results suggest that both means of measuring root nutrient uptake may be sufficient for comparing relative treatment effects across sites. However, the observed variation in magnitude suggests that caution must be taken in interpreting actual rates of uptake from either method.

  7. Value siting

    SciTech Connect

    Ferrar, T.A.; Howes, J.A.

    1995-02-01

    Finding an appropriate site is becoming an increasing challenge in building new power projects. One of the first orders of business in project development is identifying a site that offers the maximum spread between the cost of fuel and net power price. The collection of sites that exhibit an adequate spread - presenting a first-order, acceptable economic expectation - must now be subjected to an ever increasing number of political, societal, technical, and economic exclusion screens. The barriers can include cooling water constraints, community resistance, visual incompatibility, archaeological concerns and endangered species preservation issues. Most power siting difficulties can be substantially mitigated by gaining access to developed, but under-used sites, whose current owners are bound by circumstances - political or financial - that prevent them from using such locations. There are two such categories of sites: Utilities that have sites on which depreciated power production assets rest; and, The federal government, with numerous sites throughout the country, particularly military bases subject to closure under the Base Realignment and Closure (BRAC) proceedings. It is in the interests of developers, as well as consumers, investors and taxpayers, ti undertake a thorough examination of these overlooked pearls of opportunities and develop their potential.

  8. Characterization of (+/-)-methadone uptake by rat lung.

    PubMed Central

    Chi, C H; Dixit, B N

    1977-01-01

    1. By use of a sensitive and specific fluorescence assay procedure it was shown that after subcutaneous administration to rats, (+/-)-methadone was concentrated in the lung. Lung to serum ratios ranging from 25 to 60 were obtained indicating that the rat lung tissue was capable of extracting (+/-)-methadone against a concentration gradient. 2. This phenomenon was investigated in vitro with rat lung slices incubated in Krebs-Ringer phosphate buffer (pH 7.4). The uptake was expressed in terms of tissue to medium concentration ratios (T/M ratio). 3. The principal observations were: (i) Studies on the time-course of the uptake showed that the T/M ratios of (+/-)-methadone increased rapidly during the first 60 min of incubation and then more slowly, with a plateau occurring at 180 min; (ii) The T/M ratio of (+/-)-methadone progressively increased from 9.5 to 17 as the pH of the incubation medium was varied from 6.2 to 7.5; (iii) When the concentration of (+/-)-methadone in the incubation medium was varied from 0.005 to 0.5 mM, the T/M ratio decreased rapidly suggesting self-saturation of the transport process. Beyond the medium concentration of 0.5 mM, the T/M ratio declined very slowly. 4. These results suggested that at low concentrations, (+/-)-methadone was transported predominantly by a self-saturable process while at higher concentrations it was transported by a process of simple diffusion. 5. At low concentrations (0.01 mM) the uptake of (+)-methadone was higher than that of (-)-isomer indicating stereo-specificity of the uptake process. The uptake of (+/-)-methadone at low concentration (0.01 mM) was significantly inhibited by low temperature, lack of O2, lack of glucose, lack of Na+ in the incubation medium, and by exposure of the tissue to high temperature (approximately 100 degrees C). The uptake was also inhibited by relatively high concentration of iodoacetate (1.0 mM) and of naloxone (1.0 mM). 6. Kinetic analysis of data showed that the diffusion constant

  9. An exposure system for measuring nasal and lung uptake of vapors in rats

    SciTech Connect

    Dahl, A.R.; Brookins, L.K.; Gerde, P.

    1995-12-01

    Inhaled gases and vapors often produce biological damage in the nasal cavity and lower respiratory tract. The specific site within the respirator tract at which a gas or vapor is absorbed strongly influences the tissues at risk to potential toxic effects; to predict or to explain tissue or cell specific toxicity of inhaled gases or vapors, the sites at which they are absorbed must be known. The purpose of the work reported here was to develop a system for determining nose and lung absorption of vapors in rats, an animal commonly used in inhalation toxicity studies. In summary, the exposure system described allows us to measure in the rate: (1) nasal absorption and desorption of vapors; (2) net lung uptake of vapors; and (3) the effects of changed breathing parameters on vapor uptake.

  10. Stimulation of Cadmium Uptake in Relation to the Cadmium Content of Plants 1

    PubMed Central

    Petit, Charles M.; Ringoet, Arthur; Myttenaere, Constant

    1978-01-01

    The time course of cadmium uptake by the roots of intact tomato plants (Lycopersicon esculentum Mill.) was measured in a nutrient solution with a micromolar cadmium concentration until all cadmium in the medium was exhausted. Exhaustion taking a few hours, cadmium was repeatedly added to the nutrient solution. The initial rate of cadmium uptake was computed for each cadmium addition. This rate sharply increased and ultimately leveled off, the maximum value being about three times higher than the value measured after the first cadmium addition. The stimulating effect of cadmium was associated with an inhibitory effect at higher levels of cadmium concentrations. An increase in the net cadmium influx with time could not be explained by the binding of heavy metal to a fixed number of organic compounds. Conceivably, the production of binding sites could be increased and cadmium might play a part in controlling the rate of sites production. PMID:16660557

  11. Influence of the physicochemical characteristics of pollutants on their uptake in moss

    NASA Astrophysics Data System (ADS)

    Varela, Z.; Fernández, J. A.; Real, C.; Carballeira, A.; Aboal, J. R.

    2015-02-01

    Bryophytes are commonly used as biomonitors to estimate the atmospheric deposition of heavy metals and metalloids. However, the tissue concentrations of these elements in moss do not always accurately reflect atmospheric levels. The aim of the present study was to investigate whether element uptake in moss is affected by the physicochemical characteristics of the elements. Factor analysis was used to identify any patterns of covariance in the accumulation of elements in samples of the moss Pseudoscleropodium purum collected from the surroundings of different factories and from control sites. The variation in the concentrations of elements was similar in moss from both types of sites and was related to the binding properties of the elements. This suggests that the physicochemical characteristics of the elements determine the uptake of metals and metalloids from the atmosphere. Therefore, in studies that use multiple correlations among elements as indicators of a common origin of contaminants, erroneous conclusions may be reached by overlooking the adsorption properties of the moss.

  12. Gallium-68 PSMA uptake in adrenal adenoma.

    PubMed

    Law, W Phillip; Fiumara, Frank; Fong, William; Miles, Kenneth A

    2016-08-01

    Gallium-68 (Ga-68) labelled prostate-specific membrane antigen (PSMA) imaging by positron emission tomography (PET) has emerged as a promising tool for staging of prostate cancer and restaging of disease in recurrence or biochemical failure after definitive treatment of prostate cancer. Ga-68 PSMA PET produces high target-to-background images of prostate cancer and its metastases which are reflective of the significant overexpression of PSMA in these cells and greatly facilitates tumour detection. However, relatively little is known about the PSMA expression of benign neoplasms and non-prostate epithelial malignancies. This is a case report of PSMA uptake in an adrenal adenoma incidentally discovered on PET performed for restaging of biochemically suspected prostate cancer recurrence. With the increasing use of PSMA PET in the management of prostate cancer - and the not infrequent occurrence of adrenal adenomas - the appearance of low- to moderate-grade PSMA uptake in adrenal adenomas should be one with which reporting clinicians are familiar.

  13. Calcium Uptake in Crude Tissue Preparation.

    PubMed

    Bidwell, Philip A; Kranias, Evangelia G

    2016-01-01

    The various isoforms of the sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) are responsible for the Ca(2+) uptake from the cytosol into the endoplasmic or sarcoplasmic reticulum (ER/SR). In some tissues, the activity of SERCA can be modulated by binding partners, such as phospholamban and sarcolipin. The activity of SERCA can be characterized by its apparent affinity for Ca(2+) as well as maximal enzymatic velocity. Both parameters can be effectively determined by the protocol described here. Specifically, we describe the measurement of the rate of oxalate-facilitated (45)Ca uptake into the SR of crude mouse ventricular homogenates. This protocol can easily be adapted for different tissues and animal models as well as cultured cells.

  14. Computer program for calculation of oxygen uptake

    NASA Technical Reports Server (NTRS)

    Castle, B. L.; Castle, G.; Greenleaf, J. E.

    1979-01-01

    A description and operational precedures are presented for a computer program, written in Super Basic, that calculates oxygen uptake, carbon dioxide production, and related ventilation parameters. Program features include: (1) the option of entering slope and intercept values of calibration curves for the O2 and CO2 and analyzers; (2) calculation of expired water vapor pressure; and (3) the option of entering inspured O2 and CO2 concentrations. The program is easily adaptable for programmable laboratory calculators.

  15. Uranium uptake by hydroponically cultivated crop plants.

    PubMed

    Soudek, Petr; Petrová, Sárka; Benešová, Dagmar; Dvořáková, Marcela; Vaněk, Tomáš

    2011-06-01

    Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC(50) value about 0.1mM. Cucumis sativa represented the most resistant plant to uranium (EC(50)=0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1mM or 0.5mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation.

  16. Varicella vaccine uptake in Shandong province, China

    PubMed Central

    Xu, Aiqiang; Xu, Qing; Fang, Xueqiang; Bialek, Stephanie; Wang, Chengbin

    2012-01-01

    Varicella vaccine has been licensed in China for decade to be used as single dose in children aged ≥ 12 mo of age in private sector. Little data were available on varicella uptake to date in China yet. A cross-sectional study was conducted in Shandong Province in May 2011 to examine varicella vaccination coverage among children aged 16–40 mo and examine factors associated with varicella vaccine uptake. The overall coverage among children eligible for varicella vaccine was 62% (range 16.7–94.7% by county), much lower than the coverage of the eight vaccines included in the national immunization program (all above 97%). Though proximity to immunization services (< 5 km) was linked with higher vaccine uptake (62.6 vs. 37.4%, p = 0.02), county-level economic development (77.8, 61.0 and 47.1% for developed, sub-developed and developing regions, respectively, p < 0.001) played an even more important role in varicella vaccination. Moreover, there was little variation in coverage of vaccines included in the national immunization program along with county-level economic development. Even though varicella vaccine uptake is relatively high for use on a private basis, the vaccination coverage is not high enough to prevent epidemiology shift to adolescents and adults who are more prone to develop severe outcomes to varicella. Further enhancement on varicella vaccination coverage is necessary and inclusion to national immunization program seems to be a promising option for achieving and maintaining high coverage. PMID:22894966

  17. A thermodynamic formulation of root water uptake

    NASA Astrophysics Data System (ADS)

    Hildebrandt, A.; Kleidon, A.; Bechmann, M.

    2015-12-01

    By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how the energetics involved in root water uptake can be quantified. The illustration is done using a simple, four-box model of the soil-root system to represent heterogeneity and a parameterization in which root water uptake is driven by the xylem potential of the plant with a fixed flux boundary condition. We use this approach to evaluate the effects of soil moisture heterogeneity and root system properties on the dissipative losses and export of energy involved in root water uptake. For this, we derive an expression that relates the energy export at the root collar to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We conclude that such a thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path and explicitly accounting not only for the resistances along the flow path and those imposed by soil drying but especially the role of heterogenous soil water distribution. The results show that least energy needs to be exported and dissipative losses are minimized by a root system if it extracts water uniformly from the soil. This has implications for plant water relations in forests where canopies generate heterogenous input patterns. Our diagnostic in the energy domain should be useful in future model applications for quantifying how plants can evolve towards greater efficiency in their structure and function, particularly in heterogenous soil environments. Generally, this approach may help to better describe heterogeneous processes in the soil in a simple, yet physically-based way.

  18. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to...

  19. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to...

  20. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to...

  1. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to...

  2. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to...

  3. Uptake as a Mechanism to Promote Student Learning

    ERIC Educational Resources Information Center

    Bell, Clare Valerie

    2013-01-01

    This study is a descriptive examination of uptake that occurred during classroom discourse in 33 Algebra I classrooms in nine U.S. states. Uptake refers to the act of taking up mathematical comments, questions, and constructions as objects of discourse. Uptake is important because it can be used for scaffolding authentic opportunities to learn and…

  4. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  5. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  6. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  7. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  8. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  9. Capturing Individual Uptake: Toward a Disruptive Research Methodology

    ERIC Educational Resources Information Center

    Bastian, Heather

    2015-01-01

    This article presents and illustrates a qualitative research methodology for studies of uptake. It does so by articulating a theoretical framework for qualitative investigations of uptake and detailing a research study designed to invoke and capture students' uptakes in a first-year writing classroom. The research design sought to make uptake…

  10. 21 CFR 892.1320 - Nuclear uptake probe.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear uptake probe. 892.1320 Section 892.1320...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1320 Nuclear uptake probe. (a) Identification. A nuclear uptake probe is a device intended to measure the amount of radionuclide taken up by...

  11. 21 CFR 892.1320 - Nuclear uptake probe.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nuclear uptake probe. 892.1320 Section 892.1320...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1320 Nuclear uptake probe. (a) Identification. A nuclear uptake probe is a device intended to measure the amount of radionuclide taken up by...

  12. 21 CFR 892.1320 - Nuclear uptake probe.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear uptake probe. 892.1320 Section 892.1320...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1320 Nuclear uptake probe. (a) Identification. A nuclear uptake probe is a device intended to measure the amount of radionuclide taken up by...

  13. 21 CFR 892.1320 - Nuclear uptake probe.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear uptake probe. 892.1320 Section 892.1320...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1320 Nuclear uptake probe. (a) Identification. A nuclear uptake probe is a device intended to measure the amount of radionuclide taken up by...

  14. 21 CFR 892.1320 - Nuclear uptake probe.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nuclear uptake probe. 892.1320 Section 892.1320...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1320 Nuclear uptake probe. (a) Identification. A nuclear uptake probe is a device intended to measure the amount of radionuclide taken up by...

  15. Spatial analysis of agri-environmental policy uptake and expenditure in Scotland.

    PubMed

    Yang, Anastasia L; Rounsevell, Mark D A; Wilson, Ronald M; Haggett, Claire

    2014-01-15

    Agri-environment is one of the most widely supported rural development policy measures in Scotland in terms of number of participants and expenditure. It comprises 69 management options and sub-options that are delivered primarily through the competitive 'Rural Priorities scheme'. Understanding the spatial determinants of uptake and expenditure would assist policy-makers in guiding future policy targeting efforts for the rural environment. This study is unique in examining the spatial dependency and determinants of Scotland's agri-environmental measures and categorised options uptake and payments at the parish level. Spatial econometrics is applied to test the influence of 40 explanatory variables on farming characteristics, land capability, designated sites, accessibility and population. Results identified spatial dependency for each of the dependent variables, which supported the use of spatially-explicit models. The goodness of fit of the spatial models was better than for the aspatial regression models. There was also notable improvement in the models for participation compared with the models for expenditure. Furthermore a range of expected explanatory variables were found to be significant and varied according to the dependent variable used. The majority of models for both payment and uptake showed a significant positive relationship with SSSI (Sites of Special Scientific Interest), which are designated sites prioritised in Scottish policy. These results indicate that environmental targeting efforts by the government for AEP uptake in designated sites can be effective. However habitats outside of SSSI, termed here the 'wider countryside' may not be sufficiently competitive to receive funding in the current policy system.

  16. PARTITIONING THE RELATIVE INFLUENCE OF SOIL N, MYCORRHIZAE, AND FOLIAR N UPTAKE ON FOLIAR δ15N PATTERNS: CAN WE DETECT FOLIAR UPTAKE OF REACTIVE N?

    NASA Astrophysics Data System (ADS)

    Vallano, D.; Sparks, J. P.

    2009-12-01

    Vegetation is an important sink for atmospheric reactive N in N-limited systems and may be capable of incorporating reactive N compounds directly into leaves through the foliar uptake pathway. A proxy for atmospheric reactive N entering vegetation would be useful to estimate the impact of direct foliar N uptake on plant metabolism. Natural abundance foliar N isotopic composition (δ15N) is a practical tool for this purpose because plant-available N sources often have different isotopic compositions. Current understanding of foliar δ15N suggests these values primarily represent the integration of soil δ15N, direct foliar N uptake, mycorrhizal fractionation, and within-plant fractionations. Using a potted plant mesocosm system, we estimated the influence of mycorrhizae on foliar δ15N patterns in red maple (Acer rubrum) seedlings along an N deposition gradient in New York State. We found that mycorrhizal associations altered foliar δ15N in red maple seedlings from 0.03 - 1.01‰ across sites. Along the same temporal and spatial scales, we examined the influence of soil δ15N, foliar N uptake, and mycorrhizae on foliar δ15N in adult stands of American beech (Fagus grandifolia), black birch (Betula lenta), red maple (A. rubrum), and red oak (Quercus rubra). Using multiple regression models, atmospheric NO2 concentration explained 0%, 69%, 23%, and 45% of the residual variation in foliar δ15N remaining in American beech, red maple, red oak, and black birch, respectively, after accounting for soil δ15N. Our results suggest that foliar δ15N may be used to estimate pollution-derived atmospheric reactive N entering vegetation via the foliar N uptake pathway.

  17. Arsenic uptake and metabolism in plants.

    PubMed

    Zhao, F J; Ma, J F; Meharg, A A; McGrath, S P

    2009-03-01

    Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans.Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite,the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified. PMID:19207683

  18. A thermodynamic formulation of root water uptake

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Anke; Kleidon, Axel; Bechmann, Marcel

    2016-08-01

    By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how root water uptake can be evaluated thermodynamically and demonstrate that this evaluation provides additional insights into the factors that impede root water uptake. We derive an expression that relates the energy export at the base of the root system to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We illustrate this thermodynamic formulation using an idealized setup of scenarios with a simple model. In these scenarios, we demonstrate why heterogeneity in soil water distribution and rooting properties affect the impediment of water flow even though the mean soil water content and rooting properties are the same across the scenarios. The effects of heterogeneity can clearly be identified in the thermodynamics of the system in terms of differences in dissipative losses and hydraulic energy, resulting in an earlier start of water limitation in the drying cycle. We conclude that this thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path, which goes beyond resistances and also accounts for the role of heterogeneity in soil water distribution.

  19. Arsenic uptake and metabolism in plants.

    PubMed

    Zhao, F J; Ma, J F; Meharg, A A; McGrath, S P

    2009-03-01

    Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans.Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite,the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified.

  20. Modeling carbon monoxide uptake during work

    SciTech Connect

    Bernard, T.E.; Duker, J.

    1981-05-01

    Acute carbon monoxide poisoning is the result of a diminished capacity of the blood to transport oxygen and sustain a level of metabolic activity. The diminished capacity is expressed in terms of the carboxyhemoglobin (COHb) level in the blood which is dependent upon the concentration of CO in the inhaled air. The rate of CO uptake or elimination is dependent upon the concentration of CO in the air as well as pulmonary diffusion capacity and alveolar ventilation which change with different metabolic rates. Coburn, Forster, and Kane (CFK) developed a mathematical model to describe the uptake and elimination kinetics of CO in sedentary individuals. The CFK model was used in a mathematical simulation of CO uptake and elimination where the independent variables were inhaled CO concentration and metabolic rate. The metabolic rate was used to specify pulmonary diffusing capacity and alveolar ventilation. As the level of COHb increased the metabolic rate was decreased to a level compatible with the impaired oxygen transport. A physical fatigue limit was also included. The theoretical model was used to simulate conditions beyond the range of exposures permissible under experimental laboratory conditions.

  1. Water Uptake in PEMFC Catalyst Layers

    SciTech Connect

    Gunterman, Haluna P.; Kwong, Anthony H.; Gostick, Jeffrey T.; Kusoglu, Ahmet; Weber, Adam Z.

    2011-07-01

    Water uptake profiles of proton-exchange-membrane fuel-cell catalyst layers are characterized in the form of capillary-pressure saturation (Pc-S) curves. The curves indicate that the catalyst layers tested are highly hydrophilic and require capillary pressures as low as -80 kPa to eject imbibed water. Comparison of materials made with and without Pt indicates a difference in water ejection and uptake phenomena due to the presence of Pt. The addition of Pt increases the tendency of the catalyst layer to retain water. Dynamic vapor sorption (DVS) is used to characterize the water-vapor sorption onto Nafion, Pt/C, and C surfaces. The DVS results align with the trends found from the Pc-S curves and show an increased propensity for water uptake in the presence of Pt. The effect of the ion in Nafion, sodium or protonated form, is also compared and demonstrates that although the protonation of the Nafion in the catalyst layer also increases hydrophilicity, the effect is not as great as that caused by Pt.

  2. Identification of the First Highly Subtype-Selective Inhibitor of Human GABA Transporter GAT3.

    PubMed

    Damgaard, Maria; Al-Khawaja, Anas; Vogensen, Stine B; Jurik, Andreas; Sijm, Maarten; Lie, Maria E K; Bæk, Mathias I; Rosenthal, Emil; Jensen, Anders A; Ecker, Gerhard F; Frølund, Bente; Wellendorph, Petrine; Clausen, Rasmus P

    2015-09-16

    Screening a library of small-molecule compounds using a cell line expressing human GABA transporter 3 (hGAT3) in a [(3)H]GABA uptake assay identified isatin derivatives as a new class of hGAT3 inhibitors. A subsequent structure-activity relationship (SAR) study led to the identification of hGAT3-selective inhibitors (i.e., compounds 20 and 34) that were superior to the reference hGAT3 inhibitor, (S)-SNAP-5114, in terms of potency (low micromolar IC50 values) and selectivity (>30-fold selective for hGAT3 over hGAT1/hGAT2/hBGT1). Further pharmacological characterization of compound 20 (5-(thiophen-2-yl)indoline-2,3-dione) revealed a noncompetitive mode of inhibition at hGAT3. This suggests that this compound class, which has no structural resemblance to GABA, has a binding site different from the substrate, GABA. This was supported by a molecular modeling study that suggested a unique binding site that matched the observed selectivity, inhibition kinetics, and SAR of the compound series. These compounds are the most potent GAT3 inhibitors reported to date that provide selectivity for GAT3 over other GABA transporter subtypes.

  3. Cloning, expression, and characterization of cadmium and manganese uptake genes from Lactobacillus plantarum

    SciTech Connect

    Hao, Z.; Chen, S.; Wilson, D.B.

    1999-11-01

    An Mn{sup 2+} and Cd{sup 2+} uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd{sup 2+} sensitivity as well as energy-dependent Cd{sup 2+} uptake activity. Both transcription and translation of mntA were induced by Mn{sup 2+} starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd{sup 2+} uptake systems have been identified in L. plantarum: one is a high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system that is expressed in Mn{sup 2+}-starved cells, and the other is a nonsaturable Cd{sup 2+} uptake system that is expressed in Cd{sup 2+}-sufficient cells. MntA was not detected in an Mn{sup 2+}-dependent mutant of L. plantarum which had lost high-affinity Mn{sup 2+} and Cd{sup 2+} uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn{sup 2+} and Cd{sup 2+} transporter. On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases. The topology and potential Mn{sup 2+}- and Cd{sup 2+}-binding sites of MntA are discussed. A second clone containing a low-affinity Cd{sup 2+} transport system was also isolated.

  4. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia.

    PubMed

    Millett, J; Foot, G W; Svensson, B M

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant-prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. PMID:25655989

  5. Sodium-Glucose Transporter-2 (SGLT2; SLC5A2) Enhances Cellular Uptake of Aminoglycosides

    PubMed Central

    Jiang, Meiyan; Wang, Qi; Karasawa, Takatoshi; Koo, Ja-Won; Li, Hongzhe; Steyger, Peter S.

    2014-01-01

    Aminoglycoside antibiotics, like gentamicin, continue to be clinically essential worldwide to treat life-threatening bacterial infections. Yet, the ototoxic and nephrotoxic side-effects of these drugs remain serious complications. A major site of gentamicin uptake and toxicity resides within kidney proximal tubules that also heavily express electrogenic sodium-glucose transporter-2 (SGLT2; SLC5A2) in vivo. We hypothesized that SGLT2 traffics gentamicin, and promotes cellular toxicity. We confirmed in vitro expression of SGLT2 in proximal tubule-derived KPT2 cells, and absence in distal tubule-derived KDT3 cells. D-glucose competitively decreased the uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent analog of glucose, and fluorescently-tagged gentamicin (GTTR) by KPT2 cells. Phlorizin, an SGLT2 antagonist, strongly inhibited uptake of 2-NBDG and GTTR by KPT2 cells in a dose- and time-dependent manner. GTTR uptake was elevated in KDT3 cells transfected with SGLT2 (compared to controls); and this enhanced uptake was attenuated by phlorizin. Knock-down of SGLT2 expression by siRNA reduced gentamicin-induced cytotoxicity. In vivo, SGLT2 was robustly expressed in kidney proximal tubule cells of heterozygous, but not null, mice. Phlorizin decreased GTTR uptake by kidney proximal tubule cells in Sglt2+/− mice, but not in Sglt2−/− mice. However, serum GTTR levels were elevated in Sglt2−/− mice compared to Sglt2+/− mice, and in phlorizin-treated Sglt2+/− mice compared to vehicle-treated Sglt2+/− mice. Loss of SGLT2 function by antagonism or by gene deletion did not affect gentamicin cochlear loading or auditory function. Phlorizin did not protect wild-type mice from kanamycin-induced ototoxicity. We conclude that SGLT2 can traffic gentamicin and contribute to gentamicin-induced cytotoxicity. PMID:25268124

  6. Computational screening of iodine uptake in zeolitic imidazolate frameworks in a water-containing system.

    PubMed

    Yuan, Yue; Dong, Xiuqin; Chen, Yifei; Zhang, Minhua

    2016-08-17

    Iodine capture is of great environmental significance due to the high toxicity and volatility of I2. Here we conduct a systematic computational investigation of iodine adsorption in zeolitic imidazolate frameworks (ZIFs) by adopting the grand canonical Monte Carlo (GCMC) simulation and the density functional theory (DFT) method. The results confirm the vital structural factors for iodine adsorption at 298 K and moderate pressures including metal sites, organic linkers, symmetry, and topology types. The uptake will be enhanced by active metal sites, the simple imidazolate linker and single asymmetric linkers with polar functional groups. The symmetry effect is stronger than the surface properties. Meanwhile low steric hindrance is more beneficial than polar functional groups to iodine adsorption. The specific topology types like mer bringing large surface areas and large diameter cages result in high iodine capacities. Iodine molecules tend to locate in cages with large diameters and aggregates along the sides of cages. In contrast, water prefers small diameter cages. In hydrophilic materials, water has a negative impact on iodine uptake due to its similar adsorption sites to iodine. The selectivity of iodine over water increases with increasing water content due to the large diameter cages of ZIFs. This work proves that ZIFs can be identified as efficient and economical adsorbents with high diversity for iodine in a water-containing system. Furthermore, it provides comprehensive insights into key structural factors for iodine uptake and separation in silver-free porous solids. PMID:27499079

  7. Modelling water uptake efficiency of root systems

    NASA Astrophysics Data System (ADS)

    Leitner, Daniel; Tron, Stefania; Schröder, Natalie; Bodner, Gernot; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry; Schnepf, Andrea

    2016-04-01

    Water uptake is crucial for plant productivity. Trait based breeding for more water efficient crops will enable a sustainable agricultural management under specific pedoclimatic conditions, and can increase drought resistance of plants. Mathematical modelling can be used to find suitable root system traits for better water uptake efficiency defined as amount of water taken up per unit of root biomass. This approach requires large simulation times and large number of simulation runs, since we test different root systems under different pedoclimatic conditions. In this work, we model water movement by the 1-dimensional Richards equation with the soil hydraulic properties described according to the van Genuchten model. Climatic conditions serve as the upper boundary condition. The root system grows during the simulation period and water uptake is calculated via a sink term (after Tron et al. 2015). The goal of this work is to compare different free software tools based on different numerical schemes to solve the model. We compare implementations using DUMUX (based on finite volumes), Hydrus 1D (based on finite elements), and a Matlab implementation of Van Dam, J. C., & Feddes 2000 (based on finite differences). We analyse the methods for accuracy, speed and flexibility. Using this model case study, we can clearly show the impact of various root system traits on water uptake efficiency. Furthermore, we can quantify frequent simplifications that are introduced in the modelling step like considering a static root system instead of a growing one, or considering a sink term based on root density instead of considering the full root hydraulic model (Javaux et al. 2008). References Tron, S., Bodner, G., Laio, F., Ridolfi, L., & Leitner, D. (2015). Can diversity in root architecture explain plant water use efficiency? A modeling study. Ecological modelling, 312, 200-210. Van Dam, J. C., & Feddes, R. A. (2000). Numerical simulation of infiltration, evaporation and shallow

  8. Developmental features of rat cerebellar neural cells cultured in a chemically defined medium

    SciTech Connect

    Gallo, V.; Ciotti, M.T.; Aloisi, F.; Levi, G.

    1986-01-01

    We studied some aspects of the differentiation of rat cerebellar neural cells obtained from 8-day postnatal animals and cultured in a serum-free, chemically defined medium (CDM). The ability of the cells to take up radioactive transmitter amino acids was analyzed autoradiographically. The L-glutamate analogue /sup 3/H-D-aspartate was taken up by astroglial cells, but not by granule neurons, even in late cultures (20 days in vitro). This is in agreement with the lack of depolarization-induced release of /sup 3/H-D-aspartate previously observed in this type of culture. In contrast, /sup 3/H-(GABA) was scarcely accumulated by glial-fibrillary-acidic-protein (GFAP)-positive astrocytes, but taken up by glutamate-decarboxylase-positive inhibitory interneurons and was released in a Ca2+-dependent way upon depolarization: /sup 3/H-GABA evoked release progressively increased with time in culture. Interestingly, the expression of the vesicle-associated protein synapsin I was much reduced in granule cells cultured in CDM as compared to those maintained in the presence of serum. These data would indicate that in CDM the differentiation of granule neurons is not complete, while that of GABAergic neurons is not greatly affected. Whether the diminished differentiation of granule cells must be attributed only to serum deprivation or also to other differences in the composition of the culture medium remains to be established. /sup 3/H-GABA was avidly taken up also by a population of cells which were not recognized by antibodies raised against GFAP, glutamate decarboxylase, and microtubule-associated protein 2. These cells have been characterized as bipotential precursors of oligodendrocytes and of a subpopulation of astrocytes bearing a stellate shape and capable of high-affinity /sup 3/H-GABA uptake.

  9. Repetitive mechanical strain suppresses macrophage uptake of immunoglobulin G complexes and enhances cyclic adenosine monophosphate synthesis.

    PubMed Central

    Mattana, J.; Sankaran, R. T.; Singhal, P. C.

    1995-01-01

    Uptake of immunoglobulin G (IgG) complexes by macrophages (M phi) may play an important role in disease states characterized by increased levels of circulating immune complexes. In sites such as the glomerular mesangium M phi may be subjected to repetitive mechanical strain, although in vitro studies of M phi endocytosis are typically carried out with cells grown on rigid surfaces. We undertook the present study to determine whether repetitive mechanical strain could modulate M phi endocytosis of IgG complexes. IgG complex uptake was significantly diminished in M phi that were subjected to repetitive mechanical strain using parameters corresponding to peak and minimal intraglomerular pressures compared with control, and uptake varied according to the amount of mechanical strain applied. There was no significant difference in surface binding of IgG between M phi subjected to strain and those not. Mechanical strain did not significantly influence the rate of IgG complex degradation. Inhibition of nitric oxide synthase and guanylate cyclase activity did not alter the effect of mechanical strain, although this effect was potentiated by 3-isobutyl-1-methylxanthine (IBMX). Angiotensin II, which has been shown to reduce adenosine 3',5'-cyclic monophosphate (cAMP) production in M phi, significantly attenuated the suppressive effect of mechanical strain on IgG complex uptake as well as another inhibitor of cAMP generation, indomethacin. Enzyme immunoassay demonstrated significantly enhanced levels of cAMP in M phi that were subjected to mechanical strain compared with control, an effect that was potentiated by IBMX and attenuated by angiotensin II and indomethacin. These results demonstrate that repetitive mechanical strain significantly reduces IgG complex uptake by M phi, most likely by enhancing cAMP synthesis. Such an effect might play a significant role in macromolecule handling by M phi in sites in which they are subjected to repetitive mechanical deformation such as

  10. Foliar concentrations of volunteer willows growing on polluted sediment-derived sites versus sites with baseline contamination levels.

    PubMed

    Vandecasteele, Bart; Quataert, Paul; De Vos, Bruno; Tack, Filip M G; Muys, Bart

    2004-04-01

    Many alluvial soils along navigable waterways are affected by disposal of dredged sediments or overbank sedimentation and contain metal concentrations that are elevated compared to baseline levels. Uptake patterns for metals and other elements by several volunteer Salix species growing on these sites were determined during a growing season in field plots and compared with the same species growing on soils with baseline contamination levels. For Cd and Zn, foliar concentrations were clearly higher on dredged sediment landfills. Uptake patterns differed significantly between species. A high uptake of Mn and low uptake of Cu, K and S in S. cinerea was attributed to wetland soil chemistry. Site effects on metal uptake were evaluated in more detail for Salix cinerea and S. alba growing on different sediment-derived sites under field conditions. Foliar Cd concentrations were higher in S. cinerea than in S. alba. This appeared to be a genetic feature not influenced by soil chemical properties, as it was observed both on clean sites and polluted sediment-derived sites. For S. cinerea, soil chemistry was reflected in foliar concentrations, while foliar Cd concentrations and bioavailability were found to be independent of the thickness of the polluted horizon. Dredged sediment landfills and freshwater tidal marshes with comparable Cd soil pollution had significantly different foliar Cd concentrations.

  11. Monitoring vegetation water uptake in a semiarid riparian corridor

    NASA Astrophysics Data System (ADS)

    Robinson, J.; Ochoa, C. G.; Leonard, J.

    2015-12-01

    With a changing global climate and growing demand for water throughout the world, responsible and sustainable land and water resource management practices are becoming increasingly important. Accounting for the amount of water used by riparian vegetation is a critical element for better managing water resources in arid and semiarid environments. The objective of this study was to determine water uptake by selected riparian vegetative species in a semiarid riparian corridor in North-Central Oregon. Exo-skin sap flow sensors (Dynamax, Houston, TX, U.S.A.) were used to measure sap flux in red alder (Alnus rubra) trees, the dominant overstory vegetation at the field site. Xylem sap flow data was collected from selected trees at the field site and in a greenhouse setting. Transpiration rates were determined based on an energy balance method, which makes it possible to estimate the mass flow of sap by measuring the velocity of electrical heat pulses through the plant stem. Preliminary field results indicate that red alder tree branches of about 1 inch diameter transpire between 2 and 6 kg of water/day. Higher transpiration rates of up to 7.3 kg of water/day were observed under greenhouse conditions. Streamflow and stream water temperature, vegetation characteristics, and meteorological data were analyzed in conjunction with transpiration data. Results of this study provide insight on riparian vegetation water consumption in water scarce ecosystems. This study is part of an overarching project focused on climate-vegetation interactions and ecohydrologic processes in arid and semiarid landscapes.

  12. Modeling vapor uptake induced mobility shifts in peptide ions observed with transversal modulation ion mobility spectrometry-mass spectrometry.

    PubMed

    Rawat, Vivek K; Vidal-de-Miguel, Guillermo; Hogan, Christopher J

    2015-10-21

    Low field ion mobility spectrometry-mass spectrometry (IMS-MS) techniques exhibit low orthogonality, as inverse mobility often scales with mass to charge ratio. This inadequacy can be mitigated by adding vapor dopants, which may cluster with analyte ions and shift their mobilities by amounts independent of both mass and mobility of the ion. It is therefore important to understand the interactions of vapor dopants with ions, to better quantify the extent of dopant facilitated mobility shifts. Here, we develop predictive models of vapor dopant facilitated mobility shifts, and compare model calculations to measurements of mobility shifts for peptide ions exposed to variable gas phase concentrations of isopropanol. Mobility measurements were made at atmospheric pressure and room temperature using a recently developed transversal modulation ion mobility spectrometer (TMIMS). Results are compared to three separate models, wherein mobility shifts due to vapor dopants are attributed to changes in gas composition and (I) no vapor dopant uptake is assumed, (II) site-specific dopant uptake by the ion is assumed (approximated via a Langmuir adsorption model), and (III) site-unspecific dopant uptake by the ion is assumed (approximated via a classical nucleation model). We find that mobility shifts in peptide ions are in excellent agreement with model II, site-specific binding predictions. Conversely, mobility shifts of tetraalkylammonium ions from previous measurements were compared with these models and best agreement was found with model III predictions, i.e. site-unspecific dopant uptake.

  13. Focal 99mTc-DMSA Uptake in Lung Parenchyma Without Structural Alterations on SPECT/CT.

    PubMed

    Nursal, Gül Nihal; Reyhan, Mehmet; Yapar, Ali Fuat

    2015-11-01

    Static renal scintigraphy with Tc-DMSA is commonly used for the evaluation of renal morphology and function. Extrarenal uptake of Tc-DMSA is a rare finding described previously on sites such as bone metastasis, hemangioma, and splenic amyloidosis. We report a case with Tc-DMSA activity in the lungs.

  14. Modeling of cellular arginine uptake by more than one transporter.

    PubMed

    Nel, Marietha J; Woodiwiss, Angela J; Candy, Geoffrey P

    2012-01-01

    Determining the kinetic constants of arginine uptake by endothelial cells mediated by more than one transporter from linearization of data as Eadie-Hofstee plots or modeling which does not include the concentration of trace radiolabeled amino acid used to measure uptake may not be correct. The initial rate of uptake of trace [³H]L-arginine by HUVECs and ECV₃₀₄ cells in the presence of a range of unlabeled arginine and modifiers was used in nonlinear models to calculate the constants of arginine uptake using GraphPad Prism. Theoretical plots of uptake derived from constants determined from Eadie-Hofstee graphs overestimated uptake, whereas those from the nonlinear modeling approach agreed with experimental data. The contribution of uptake by individual transporters could be modeled and showed that leucine inhibited the individual transporters differently and not necessarily competitively. N-Ethylmaleimide inhibited only y⁺ transport, and BCH may be a selective inhibitor of y⁺L transport. The absence of sodium reduced arginine uptake by y⁺L transport and reduced the K(m)', whereas reducing sodium decreased arginine uptake by y⁺ transport without affecting the K (m)'. The nonlinear modeling approach using raw data avoided the errors inherent in methods deriving constants from the linearization of the uptake processes following Michaelian kinetics. This study provides explanations for discrepancies in the literature and suggests that a nonlinear modeling approach better characterizes the kinetics of amino acid uptake into cells by more than one transporter.

  15. Relating Nutrient Uptake And Respiration With Metabolically Active Transient Storage

    NASA Astrophysics Data System (ADS)

    Argerich, A.; Haggerty, R.; Christensen, C.

    2009-12-01

    Quantification of water transient storage zones is critical to understand stream nutrient uptake, but the common method to measure transient storage parameters (based on the use of conservative solutes as hydrologic tracers) does not allow distinguishing among different transient storage compartments that contribute in different proportions to nutrient uptake. We use an alternative experimental approach, the Resazurin (Raz) “smart” tracer, which in combination with a conservative tracer is expected to give the relation between metabolically active transient storage (MATS) versus whole transient storage. Raz is a weakly fluorescent phenoxazine dye that undergoes an irreversible reduction to highly fluorescent Resorufin (hereafter referred as Rru) in the presence of aerobic respiration. We conducted a combined injection of Raz, NaCl, NH4, and PO4 in WS01 at H.J. Andrews Experimental Forest. The injection was performed during low-baseflow conditions (Q<0.5 L/s) at a constant flow rate for 5 days. Changes in time in EC, Raz, Rru and nutrient concentrations were examined at 3 surface sampling sites and at 6 wells. Simultaneously to the injection we measured whole-reach metabolism and we performed an SF6 injection to measure the exchange coefficient of O2 between the atmosphere and stream water. The reach achieved plateau conditions in less than 15 hours after the injection began and recovered to pre-injection conditions 56 hours after the end of the injection. EC corrected by background conditions decreased with distance reflecting a dilution effect caused by the water gaining condition of the reach. Raz concentration increased and Rru concentration decreased along the reach reflecting the transformation of Raz to Rru with distance. The Rru to Raz ratio at surface water was correlated with instantaneous rates of net ecosystem production (NEP) measured over the whole reach. Percentage of surface water in wells during plateau ranged between 50% and 95%. Raz

  16. Antihistamine effect on synaptosomal uptake of serotonin, norepinephrine and dopamine

    NASA Technical Reports Server (NTRS)

    Brown, P. A.; Vernikos, J.

    1980-01-01

    A study on the effects of five H1 and H2 antihistamines on the synaptosomal uptake of serotonin (5HT), norepinephrine (NE), and dopamine (DA) is presented. Brain homogenates from female rats were incubated in Krebs-Ringer phosphate buffer solution in the presence of one of three radioactive neurotransmitters, and one of the five antihistamines. Low concentrations of pyrilamine competitively inhibited 5HT uptake, had little effect on NE uptake, and no effect on DA uptake. Promethazine, diphenhydramine, metiamide, and cimetidine had no effect on 5HT or DA uptake at the same concentration. Diphenhydramine had a small inhibitory effect on NE uptake. It is concluded that pyrilamine is a selective and potent competitive inhibitor of 5HT uptake at concentrations between .05 and .5 micromolars.

  17. Effects of calmodulin and calmodulin inhibitors on Ca uptake by sarcoplasmic reticulum of saponin skinned caudal artery

    SciTech Connect

    Stout, M.A.; Silver, P.J.

    1986-03-05

    Calmodulin (CaM) stimulates plasma membrane transport in many cell types, however, its role in Ca regulation by the sarcoplasmic reticulum (SR) in smooth muscle has not been established. /sup 45/Ca uptake was studied in saponin skinned strips of rat caudal artery as a function of CaM and the CaM inhibitors, W-7, calmidazolium (CaMZ), and trifluoperazine (TFP). Although caudal artery strips lose approximately 30% of total tissue CaM during skinning, 0.3 - 2 ..mu..M CaM did not increase /sup 45/Ca uptake over a wide range of free Ca concentrations (10/sup -8/ - 10/sup -6/M). Neither W-7 nor CaMZ at concentration of 10/sup -4/ - 2 x 10/sup -4/M inhibited the MgATP-dependent Ca uptake. Ca uptake was not affected by 50 ..mu..M TFP but a significant inhibition was produced by 500 ..mu..M. Studies of the effects of TFP on /sup 45/Ca efflux indicated that TFP concentrations which inhibited Ca uptake also significantly increased the rate of Ca release. The results suggest that total Ca uptake in caudal artery depends mainly upon MgATP and is not modulated by exogenous CaM or affected by these CaM inhibitors. They cannot preclude that CaM may affect initial velocities or that the CaM inhibitors failed to reach active sites.

  18. Elevated Uptake of Plasma Macromolecules by Regions of Arterial Wall Predisposed to Plaque Instability in a Mouse Model

    PubMed Central

    Mohri, Zahra; Rowland, Ethan M.; Clarke, Lindsey A.; De Luca, Amalia; Peiffer, Véronique; Krams, Rob; Sherwin, Spencer J.; Weinberg, Peter D.

    2014-01-01

    Atherosclerosis may be triggered by an elevated net transport of lipid-carrying macromolecules from plasma into the arterial wall. We hypothesised that whether lesions are of the thin-cap fibroatheroma (TCFA) type or are less fatty and more fibrous depends on the degree of elevation of transport, with greater uptake leading to the former. We further hypothesised that the degree of elevation can depend on haemodynamic wall shear stress characteristics and nitric oxide synthesis. Placing a tapered cuff around the carotid artery of apolipoprotein E -/- mice modifies patterns of shear stress and eNOS expression, and triggers lesion development at the upstream and downstream cuff margins; upstream but not downstream lesions resemble the TCFA. We measured wall uptake of a macromolecular tracer in the carotid artery of C57bl/6 mice after cuff placement. Uptake was elevated in the regions that develop lesions in hyperlipidaemic mice and was significantly more elevated where plaques of the TCFA type develop. Computational simulations and effects of reversing the cuff orientation indicated a role for solid as well as fluid mechanical stresses. Inhibiting NO synthesis abolished the difference in uptake between the upstream and downstream sites. The data support the hypothesis that excessively elevated wall uptake of plasma macromolecules initiates the development of the TCFA, suggest that such uptake can result from solid and fluid mechanical stresses, and are consistent with a role for NO synthesis. Modification of wall transport properties might form the basis of novel methods for reducing plaque rupture. PMID:25531765

  19. A primary fish gill cell culture model to assess pharmaceutical uptake and efflux: evidence for passive and facilitated transport.

    PubMed

    Stott, Lucy C; Schnell, Sabine; Hogstrand, Christer; Owen, Stewart F; Bury, Nic R

    2015-02-01

    The gill is the principle site of xenobiotic transfer to and from the aqueous environment. To replace, refine or reduce (3Rs) the large numbers of fish used in in vivo uptake studies an effective in vitro screen is required that mimics the function of the teleost gill. This study uses a rainbow trout (Oncorhynchus mykiss) primary gill cell culture system grown on permeable inserts, which tolerates apical freshwater thus mimicking the intact organ, to assess the uptake and efflux of pharmaceuticals across the gill. Bidirectional transport studies in media of seven pharmaceuticals (propranolol, metoprolol, atenolol, formoterol, terbutaline, ranitidine and imipramine) showed they were transported transcellularly across the epithelium. However, studies conducted in water showed enhanced uptake of propranolol, ranitidine and imipramine. Concentration-equilibrated conditions without a concentration gradient suggested that a proportion of the uptake of propranolol and imipramine is via a carrier-mediated process. Further study using propranolol showed that its transport is pH-dependent and at very low environmentally relevant concentrations (ng L(-1)), transport deviated from linearity. At higher concentrations, passive uptake dominated. Known inhibitors of drug transport proteins; cimetidine, MK571, cyclosporine A and quinidine inhibited propranolol uptake, whilst amantadine and verapamil were without effect. Together this suggests the involvement of specific members of SLC and ABC drug transporter families in pharmaceutical transport.

  20. Calcium-calmodulin-dependent kinase II (CaMKII) mediates insulin-stimulated proliferation and glucose uptake.

    PubMed

    Illario, Maddalena; Monaco, Sara; Cavallo, Anna Lina; Esposito, Iolanda; Formisano, Pietro; D'Andrea, Luca; Cipolletta, Ersilia; Trimarco, Bruno; Fenzi, Gianfranco; Rossi, Guido; Vitale, Mario

    2009-05-01

    Cellular growth and glucose uptake are regulated by multiple signals generated by the insulin receptor. The mechanisms of individual modulation of these signals remain somewhat elusive. We investigated the role of CaMKII in insulin signalling in a rat skeletal muscle cell line, demonstrating that CaMKII modulates the insulin action on DNA synthesis and the negative feedback that down regulates glucose uptake. Insulin stimulation generated partly independent signals leading to the rapid activation of Akt, Erk-1/2 and CaMKII. Akt activation was followed by Glut-4 translocation to the plasma membrane and increase of glucose uptake. Then, IRS-1 was phosphorylated at S612, the IRS-1/p85PI3K complex was disrupted, Akt was no more phosphorylated and both Glut-4 translocation and glucose uptake were reduced. Inhibition of CaMKII abrogated the insulin-induced Erk-1/2 activation, DNA synthesis and phosphorylation of IRS-1 at S612. Inhibition of CaMKII also abrogated the down-regulation of insulin-stimulated Akt phosphorylation, Glut-4 membrane translocation and glucose uptake. These results demonstrate that: 1 - CaMKII modulates the insulin-induced Erk-1/2 activation and cell proliferation; 2 - after the initial stimulation of the IRS-1/Akt pathway, CaMKII mediates the down-regulation of stimulated glucose uptake. This represents a novel mechanism in the selective control of insulin signals, and a possible site for pharmacological intervention.

  1. Influence of soil structure on unsaturated water flow including root uptake

    NASA Astrophysics Data System (ADS)

    Kuhlmann, Anna; Neuweiler, Insa; van der Zee, Sjoerd; Helmig, Rainer

    2010-05-01

    The development of effective irrigation strategies is of great importance as the scarcity of water during extended dry periods in aride areas leads to limited water uptake by roots and thus to restricted growth and eventually to wilting of plants. To approach this goal a broad understanding of the factors which influence the distribution of the water potential and the interactions with root uptake is crucial. Soil structure is supposed to have a large impact on water flow especially under dry conditions when the variability of soil parameters is increased. For field applications, predictions of the water flow are needed for large scales where the scarcity of measurements leads to a high level of uncertainty about the detailed distribution of soil parameters. Thus stochastic methods in which heterogeneity of soil is described by a random parameter field are used. In this presentation, the interrelation of root uptake and heterogeneity is analyzed using numerical simulations. Random parameter fields with Gaussian and non-Gaussian dependence were parameterized according to the Las Cruces Trench Site dataset and used as input for the numerical model. Transpiration is considered in a macroscopic way as a sink term with a prescribed potential extraction rate at each node, determined by the density distribution of the plants and with restricted uptake due to unfavorable conditions as lack of water and oxygen (modeled according to the Feddes - Function). With this basic model, water flow in two dimensional random fields has been investigated under dry conditions. It was observed that dry spots - regions in which roots dry up to the wilting point form when the structure shows isolated high extreme values in conductivity. In these dry regions, roots take up a decreased amount of water such that the total potential demand is not met anymore. This seems rather unrealistic as sufficient water is available at other locations of the domain. Thus two other approaches are analyzed

  2. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts. PMID:22578572

  3. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts.

  4. Characterization of cadmium uptake in Lactobacillus plantarum and isolation of cadmium and manganese uptake mutants

    SciTech Connect

    Hao, Z.; Reiske, H.R.; Wilson, D.B.

    1999-11-01

    Two different Cd{sup 2+} uptake systems were identified in Lactobacillus plantarum. One is a high-affinity, high-velocity Mn{sup 2+} uptake system which also takes up Cd{sup 2+} and is induced by Mn{sup 2+} starvation. The calculated K{sub m} and V{sub max} are 0.26 {mu}M and 3.6 {mu}mol g of dry cell{sup {minus}1} min{sup {minus}1}, respectively. Unlike Mn{sup 2+} uptake, which is facilitated by citrate and related tricarboxylic acids, Cd{sup 2+} uptake is weakly inhibited by citrate. Cd{sup 2+} and Mn{sup 2+} are competitive inhibitors of each other, and the affinity of the system for Cd{sup 2+} is higher than that for Mn{sup 2+}. The other Cd{sup 2+} uptake system is expressed in Mn{sup 2+}-sufficient cells, and no K{sub m} can be calculated for it because uptake is nonsaturable. Mn{sup 2+} does not compete for transport through this system, nor does any other tested cation, i.e., Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Ca{sup 2+}, Fe{sup 2+}, or Ni{sup 2+}. Both systems require energy, since uncouplers completely inhibit their activities. Two Mn{sup 2+}-dependent L. plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment. They required more than 5,000 times as much Mn{sup 2+} for growth as the parental strain. Mn{sup 2+} starvation-induced Cd{sup 2+} uptake in both mutants was less than 5% the wild-type rate. The low level of long-term Mn{sup 2+} or Cd{sup 2+} accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system.

  5. Uptake of Mass Drug Administration Programme for Schistosomiasis Control in Koome Islands, Central Uganda

    PubMed Central

    Tuhebwe, Doreen; Bagonza, James; Kiracho, Elizabeth Ekirapa; Yeka, Adoke; Elliott, Alison M.; Nuwaha, Fred

    2015-01-01

    Introduction Schistosomiasis is one of the neglected tropical diseases targeted for elimination in Uganda through the Mass Drug Administration (MDA) programme. Praziquantel has been distributed using community resource persons in fixed sites and house-to-house visits; however the uptake is still below target coverage. In 2011/2012 MDA exercise, uptake stood at 50% yet WHO target coverage is 75% at community level. We assessed the uptake of MDA and the associated factors in Koome Islands, Central Uganda. Methods In March 2013, we conducted a mixed methods cross sectional study in 15 randomly selected villages. We interviewed a total of 615 respondents aged 18 years and above using semi structured questionnaires and five key informants were also purposively selected. Univariate and multivariate analysis was done. MDA uptake was defined as self reported swallowing of praziquantel during the last (2012) MDA campaign. We conducted key informant interviews with Ministry of Health, district health personnel and community health workers. Results Self reported uptake of praziquantel was 44.7% (275/615), 95% confidence interval (CI) 40.8–48.7%. Of the 275 community members who said they had swallowed praziquantel, 142 (51.6%) reported that they had developed side effects. Uptake of MDA was more likely if the respondent was knowledgeable about schistosomiasis transmission and prevention (adjusted odds ratio [AOR] 1.85, 95% CI 1.22–2.81) and reported to have received health education from the health personnel (AOR 5.95, 95% CI 3.67–9.65). Service delivery challenges such as drug shortages and community health worker attrition also influenced MDA in Koome Islands. Conclusions Uptake of MDA for schistosomiasis control in Koome was sub optimal. Lack of knowledge about schistosomiasis transmission and prevention, inadequate health education and drug shortages are some of the major factors associated with low uptake. These could be addressed through routine health education

  6. Modeling the uptake and transpiration of TCE using phreatophytic trees. Master`s Thesis

    SciTech Connect

    Wise, D.P.

    1997-12-01

    Phytoremediation is a recent addition to the numerous methods used today to remediate ground water contaminants. It is proving more effective and efficient compared to existing remediation techniques. The use of phreatophytes, or water seeking trees, has great potential for phytoremediation. These trees are fast growing, long lived, grow their roots down to the ground water table, transpire large amounts of water, and are proven to actively remove contaminants from the soil horizon. The purpose of this research is to develop quantitative concepts for understanding the dynamics of TCE uptake and transpiration by phreatophytic trees over a short rotation woody crop time frame. This will he done by constructing a system dynamics model of this process and running it over a wide range of conditions. This research will offer managers a tool to simulate long-term uptake and transpiration of TCE at potential sites. The results of this study indicate that TCE is actively removed from the soil horizon by phreatophytic trees and a significant proportion of this TCE is then transpired. Changes in soil horizon parameters, xylem flow rates, and variables in the uptake equation greatly influence TCE uptake rates as well as transpiration. Also, parameters used in equations representing flows in and out of the leaf greatly influence transpiration. Better understanding of these processes is essential for managers to accurately predict the amount of TCE removed and transpired during potential phytoremediation projects.

  7. Selective MPP+ uptake into synaptic dopamine vesicles: possible involvement in MPTP neurotoxicity.

    PubMed Central

    Del Zompo, M.; Piccardi, M. P.; Ruiu, S.; Quartu, M.; Gessa, G. L.; Vaccari, A.

    1993-01-01

    1. In the present study we provide evidence for a saturable, Mg2+/ATP- and temperature-dependent, tetrabenazine-, dopamine-, and amphetamine-sensitive uptake of 1-methyl-4-phenylpyridinium ion (MPP+) in synaptic vesicles from mouse striatum. 2. Similarity in the properties of the vesicular uptake suggests that in the striatum dopamine and MPP+ share the vesicular carrier. 3. The presence of MPP+ vesicular uptake in dopamine-rich regions such as striatum, olfactory, tubercles and hypothalamus, as well as its absence in cerebellum, cortex and pons-medulla, suggest that monoamine vesicular carriers differ between highly and poorly dopamine-innervated regions. 4. The restriction of active MPP+ uptake to the dopaminergic regions, which reflects the previously shown distribution of [3H]-MPP+ binding sites in mouse brain membranes, indicates MPP+ as a marker of the vesicular carrier for dopamine in dopaminergic neurones. 5. A role in MPP+ neurotoxicity is suggested for this region-specific, vesicular storage of the toxin. Images Figure 1 PMID:8102929

  8. Bile acid inhibition of taurocholate uptake by rat hepatocytes: role of OH groups

    SciTech Connect

    Bellentani, S.; Hardison, W.G.M.; Marchegiano, P.; Zanasi, G.; Manenti, F.

    1987-03-01

    To define further the structural specificity of the taurocholate uptake site, the authors studied the ability of a variety of taurine-conjugated bile acids with differing hydroxyl substituents on the sterol moiety to inhibit (/sup 14/C) taurocholate uptake. Rat hepatocytes isolated by collagenase perfusion were incubated in a tris (hydroxymethyl) aminomethane-phosphate buffer containing (/sup 14/C)taurocholate in the presence or absence of inhibitor bile acid. Stronger inhibitors were studied at a fixed concentration of 5 ..mu..M, weaker ones at 25 ..mu..M. Initial uptake velocity was measured. Uptake velocity could then be related to taurocholate concentration and a V/sub max/ and K/sub m/ could be determined by applying a nonlinear least squares fit to the data obtained with or without inhibitor. The kinetic parameters allowed the determination of the type of inhibition and of inhibition constants (K/sub i/) of the various test bile acids. The data indicate that bile acids containing a 6- or 7-OH group exhibit competitive inhibition, whereas bile acids with no 6- or 7-OH group exhibit noncompetitive inhibition. Of the compounds exhibiting competitive inhibition, K/sub i/ varied with the number of hydroxyl groups on the sterol moiety. They conclude that the presence of absence of a 6- or 7-OH group dictates the mechanism of inhibition; the number of hydroxyl substituents determines the potency of competitive inhibition.

  9. Coastal-ocean uptake of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Bourgeois, Timothée; Orr, James C.; Resplandy, Laure; Terhaar, Jens; Ethé, Christian; Gehlen, Marion; Bopp, Laurent

    2016-07-01

    Anthropogenic changes in atmosphere-ocean and atmosphere-land CO2 fluxes have been quantified extensively, but few studies have addressed the connection between land and ocean. In this transition zone, the coastal ocean, spatial and temporal data coverage is inadequate to assess its global budget. Thus we use a global ocean biogeochemical model to assess the coastal ocean's global inventory of anthropogenic CO2 and its spatial variability. We used an intermediate resolution, eddying version of the NEMO-PISCES model (ORCA05), varying from 20 to 50 km horizontally, i.e. coarse enough to allow multiple century-scale simulations but finer than coarse-resolution models (˜ 200 km) to better resolve coastal bathymetry and complex coastal currents. Here we define the coastal zone as the continental shelf area, excluding the proximal zone. Evaluation of the simulated air-sea fluxes of total CO2 for 45 coastal regions gave a correlation coefficient R of 0.8 when compared to observation-based estimates. Simulated global uptake of anthropogenic carbon results averaged 2.3 Pg C yr-1 during the years 1993-2012, consistent with previous estimates. Yet only 0.1 Pg C yr-1 of that is absorbed by the global coastal ocean. That represents 4.5 % of the anthropogenic carbon uptake of the global ocean, less than the 7.5 % proportion of coastal-to-global-ocean surface areas. Coastal uptake is weakened due to a bottleneck in offshore transport, which is inadequate to reduce the mean anthropogenic carbon concentration of coastal waters to the mean level found in the open-ocean mixed layer.

  10. Sugar uptake by intestinal basolateral membrane vesicles.

    PubMed

    Wright, E M; van Os, C H; Mircheff, A K

    1980-03-27

    A high yield of membrane vesicles was prepared from the basolateral surface of rat intestinal cells using an N2 cavitation bomb and density gradient centrifugation. The membranes were enriched 10-fold and were free of significatn contamination by brush border membranes and mitochondria. The rate of D-E114C]glucose and L-E13H]glucose uptake into the vesicle was measured using a rapid filtration technique. D-Glucose equilibrated within the vesicles with a half-time 1/25th that for L-glucose. The stereospecific uptake exhibited saturation kinetics with a Km of approx. 44 mM and a V of approx. 110 nmol . mg-1 min-1 at 10 degrees C. The activation energy for the process was 14 kcal . mol-1 below 15 degrees C and it approached 3 kcal . mol-1 above 22 degrees C. Carrier-mediated uptake was eliminated in the presence of 1 mM HgCl2 and 0.5 mM phloretin. The rate of transport was unaffected by the absence or presence of sodium concentration gradients. Competition studies demonstrated that all sugars with the D-glucose pyranose ring chair conformation shared the transport system, and that, with the possible exception of the -OH group at carbon No. 1, there were no specific requirements for an equatorial -OH group at any position in the pyranose ring. In the case of alpha-methyl-D-glucoside its inability to share the D-glucose transport system may be due to steric hindrance posed by the -OCH3 group rather than by a specific requirement for a free hydroxyl group at the position in the ring. It is concluded that sugars are transported across the basolateral membrane of the intestinal epithelium by a facilitated diffusion system reminiscent of that in human red blood cells. PMID:6245688

  11. Sugar uptake by intestinal basolateral membrane vesicles.

    PubMed

    Wright, E M; van Os, C H; Mircheff, A K

    1980-03-27

    A high yield of membrane vesicles was prepared from the basolateral surface of rat intestinal cells using an N2 cavitation bomb and density gradient centrifugation. The membranes were enriched 10-fold and were free of significatn contamination by brush border membranes and mitochondria. The rate of D-E114C]glucose and L-E13H]glucose uptake into the vesicle was measured using a rapid filtration technique. D-Glucose equilibrated within the vesicles with a half-time 1/25th that for L-glucose. The stereospecific uptake exhibited saturation kinetics with a Km of approx. 44 mM and a V of approx. 110 nmol . mg-1 min-1 at 10 degrees C. The activation energy for the process was 14 kcal . mol-1 below 15 degrees C and it approached 3 kcal . mol-1 above 22 degrees C. Carrier-mediated uptake was eliminated in the presence of 1 mM HgCl2 and 0.5 mM phloretin. The rate of transport was unaffected by the absence or presence of sodium concentration gradients. Competition studies demonstrated that all sugars with the D-glucose pyranose ring chair conformation shared the transport system, and that, with the possible exception of the -OH group at carbon No. 1, there were no specific requirements for an equatorial -OH group at any position in the pyranose ring. In the case of alpha-methyl-D-glucoside its inability to share the D-glucose transport system may be due to steric hindrance posed by the -OCH3 group rather than by a specific requirement for a free hydroxyl group at the position in the ring. It is concluded that sugars are transported across the basolateral membrane of the intestinal epithelium by a facilitated diffusion system reminiscent of that in human red blood cells.

  12. Angiotensin II reduces calcium uptake into bone.

    PubMed

    Schurman, Scott J; Bergstrom, William H; Shoemaker, Lawrence R; Welch, Thomas R

    2004-01-01

    Children with neonatal Bartter syndrome (NBS) have hypercalciuria, nephrocalcinosis, and osteopenia. A complex of basic-fibroblast growth factor (b-FGF) and a naturally occurring glycosaminoglycan has been identified in the serum and urine of NBS patients. This complex increases bone resorption in a bone disc bioassay system. Angiotensin II (AT II), which is increased in Bartter syndrome, increases the synthesis of b-FGF by cultured endothelial cells. Addition of 10(-8) M AT II to the bioassay, a concentration reported in Bartter syndrome patients, significantly decreased calcium uptake into bone discs [E/C 0.60 (0.04), P < 0.001 compared with buffer, normal E/C >0.90]. Adding b-FGF monoclonal antibody at 10 microg/ml [E/C 0.90 (0.06), P=NS] or indomethacin [E/C 1.00 (0.03), P=NS] to 10(-8 )M AT II neutralized this effect. In separate experiments, newborn rats were given intraperitoneal injections of AT II. Bone discs from these animals were used in the bioassay system and calcium uptake was markedly reduced compared with discs from rats injected with phosphate-buffered saline [AT II 6.6 x 10(-9), E/C 0.10 (0.04), P<0.001, AT II 3.3 x 10(-8), E/C 0.10 (0.05), P<0.001]. AT II decreases calcium uptake in the bone disc bioassay system. This effect can be abrogated by antibody to b-FGF or prostaglandin synthetase inhibition. These results support the hypothesis that in children with NBS, elevated levels of AT II stimulate local skeletal b-FGF synthesis, with a resultant increase in bone resorption via a prostaglandin-dependent pathway. PMID:14648327

  13. A Comparative Study of Iron Uptake Rates and Mechanisms amongst Marine and Fresh Water Cyanobacteria: Prevalence of Reductive Iron Uptake

    PubMed Central

    Lis, Hagar; Kranzler, Chana; Keren, Nir; Shaked, Yeala

    2015-01-01

    In this contribution, we address the question of iron bioavailability to cyanobacteria by measuring Fe uptake rates and probing for a reductive uptake pathway in diverse cyanobacterial species. We examined three Fe-substrates: dissolved inorganic iron (Fe') and the Fe-siderophores Ferrioxamine B (FOB) and FeAerobactin (FeAB). In order to compare across substrates and strains, we extracted uptake rate constants (kin = uptake rate/[Fe-substrate]). Fe' was the most bioavailable Fe form to cyanobacteria, with kin values higher than those of other substrates. When accounting for surface area (SA), all strains acquired Fe' at similar rates, as their kin/SA were similar. We also observed homogeneity in the uptake of FOB among strains, but with 10,000 times lower kin/SA values than Fe'. Uniformity in kin/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB. In contrast, different uptake pathways were found for FeAB along with variations in kin/SA. Our data supports the existence of a common reductive Fe uptake pathway amongst cyanobacteria, functioning alone or in addition to siderophore-mediated uptake. Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates. PMID:25768677

  14. Political and economic factors influencing contraceptive uptake.

    PubMed

    Sai, F T

    1993-01-01

    International, national and local level politics influence the uptake of contraception through consensuses, laws, financial and moral support or the creation of an enabling atmosphere. Opposition to contraception generally comes from some churches and groups opposed to particular technologies. Socio-economic factors, particularly education, the health care system and the perceived or actual cost of fertility regulation as compared to benefits expected from children also powerfully influence contraceptive use. For many poor women in developing countries their powerlessness in relation to their male partners is an important obstacle.

  15. Antigen Uptake during Different Life Stages of Zebrafish (Danio rerio) Using a GFP-Tagged Yersinia ruckeri.

    PubMed

    Korbut, Rozalia; Mehrdana, Foojan; Kania, Per Walter; Larsen, Marianne Halberg; Frees, Dorte; Dalsgaard, Inger; Jørgensen, Louise von Gersdorff

    2016-01-01

    Immersion-vaccines (bacterins) are routinely used for aquacultured rainbow trout to protect against Yersinia ruckeri (Yr). During immersion vaccination, rainbow trout take up and process the antigens, which induce protection. The zebrafish was used as a model organism to study uptake mechanisms and subsequent antigen transport in fish. A genetically modified Yr was developed to constitutively express green fluorescent protein (GFP) and was used for bacterin production. Larval, juvenile and adult transparent zebrafish (tra:nac mutant) received a bath in the bacterin for up to 30 minutes. Samples were taken after 1 min, 15 min, 30 min, 2 h, 12 h and 24 h. At each sampling point fish were used for live imaging of the uptake using a fluorescence stereomicroscope and for immunohistochemistry (IHC). In adult fish, the bacterin could be traced within 30 min in scale pockets, skin, oesophagus, intestine and fins. Within two hours post bath (pb) Yr-antigens were visible in the spleen and at 24 h in liver and kidney. Bacteria were associated with the gills, but uptake at this location was limited. Antigens were rarely detected in the blood and never in the nares. In juvenile fish uptake of the bacterin was seen in the intestine 30 min pb and in the nares 2 hpb but never in scale pockets. Antigens were detected in the spleen 12 hpb. Zebrafish larvae exhibited major Yr uptake only in the mid-intestine enterocytes 24 hpb. The different life stages of zebrafish varied with regard to uptake locations, however the gut was consistently a major uptake site. Zebrafish and rainbow trout tend to have similar uptake mechanisms following immersion or bath vaccination, which points towards zebrafish as a suitable model organism for this aquacultured species. PMID:27404564

  16. Antigen Uptake during Different Life Stages of Zebrafish (Danio rerio) Using a GFP-Tagged Yersinia ruckeri

    PubMed Central

    Korbut, Rozalia; Mehrdana, Foojan; Kania, Per Walter; Larsen, Marianne Halberg; Frees, Dorte; Dalsgaard, Inger; Jørgensen, Louise von Gersdorff

    2016-01-01

    Immersion-vaccines (bacterins) are routinely used for aquacultured rainbow trout to protect against Yersinia ruckeri (Yr). During immersion vaccination, rainbow trout take up and process the antigens, which induce protection. The zebrafish was used as a model organism to study uptake mechanisms and subsequent antigen transport in fish. A genetically modified Yr was developed to constitutively express green fluorescent protein (GFP) and was used for bacterin production. Larval, juvenile and adult transparent zebrafish (tra:nac mutant) received a bath in the bacterin for up to 30 minutes. Samples were taken after 1 min, 15 min, 30 min, 2 h, 12 h and 24 h. At each sampling point fish were used for live imaging of the uptake using a fluorescence stereomicroscope and for immunohistochemistry (IHC). In adult fish, the bacterin could be traced within 30 min in scale pockets, skin, oesophagus, intestine and fins. Within two hours post bath (pb) Yr-antigens were visible in the spleen and at 24 h in liver and kidney. Bacteria were associated with the gills, but uptake at this location was limited. Antigens were rarely detected in the blood and never in the nares. In juvenile fish uptake of the bacterin was seen in the intestine 30 min pb and in the nares 2 hpb but never in scale pockets. Antigens were detected in the spleen 12 hpb. Zebrafish larvae exhibited major Yr uptake only in the mid-intestine enterocytes 24 hpb. The different life stages of zebrafish varied with regard to uptake locations, however the gut was consistently a major uptake site. Zebrafish and rainbow trout tend to have similar uptake mechanisms following immersion or bath vaccination, which points towards zebrafish as a suitable model organism for this aquacultured species. PMID:27404564

  17. Antigen Uptake during Different Life Stages of Zebrafish (Danio rerio) Using a GFP-Tagged Yersinia ruckeri.

    PubMed

    Korbut, Rozalia; Mehrdana, Foojan; Kania, Per Walter; Larsen, Marianne Halberg; Frees, Dorte; Dalsgaard, Inger; Jørgensen, Louise von Gersdorff

    2016-01-01

    Immersion-vaccines (bacterins) are routinely used for aquacultured rainbow trout to protect against Yersinia ruckeri (Yr). During immersion vaccination, rainbow trout take up and process the antigens, which induce protection. The zebrafish was used as a model organism to study uptake mechanisms and subsequent antigen transport in fish. A genetically modified Yr was developed to constitutively express green fluorescent protein (GFP) and was used for bacterin production. Larval, juvenile and adult transparent zebrafish (tra:nac mutant) received a bath in the bacterin for up to 30 minutes. Samples were taken after 1 min, 15 min, 30 min, 2 h, 12 h and 24 h. At each sampling point fish were used for live imaging of the uptake using a fluorescence stereomicroscope and for immunohistochemistry (IHC). In adult fish, the bacterin could be traced within 30 min in scale pockets, skin, oesophagus, intestine and fins. Within two hours post bath (pb) Yr-antigens were visible in the spleen and at 24 h in liver and kidney. Bacteria were associated with the gills, but uptake at this location was limited. Antigens were rarely detected in the blood and never in the nares. In juvenile fish uptake of the bacterin was seen in the intestine 30 min pb and in the nares 2 hpb but never in scale pockets. Antigens were detected in the spleen 12 hpb. Zebrafish larvae exhibited major Yr uptake only in the mid-intestine enterocytes 24 hpb. The different life stages of zebrafish varied with regard to uptake locations, however the gut was consistently a major uptake site. Zebrafish and rainbow trout tend to have similar uptake mechanisms following immersion or bath vaccination, which points towards zebrafish as a suitable model organism for this aquacultured species.

  18. Positive newborn screen for methylmalonic aciduria identifies the first mutation in TCblR/CD320, the gene for cellular uptake of transcobalamin-bound vitamin B(12).

    PubMed

    Quadros, Edward V; Lai, Shao-Chiang; Nakayama, Yasumi; Sequeira, Jeffrey M; Hannibal, Luciana; Wang, Sihe; Jacobsen, Donald W; Fedosov, Sergey; Wright, Erica; Gallagher, Renata C; Anastasio, Natascia; Watkins, David; Rosenblatt, David S

    2010-08-01

    Elevated methylmalonic acid in five asymptomatic newborns whose fibroblasts showed decreased uptake of transcobalamin-bound cobalamin (holo-TC), suggested a defect in the cellular uptake of cobalamin. Analysis of TCblR/CD320, the gene for the receptor for cellular uptake of holo-TC, identified a homozygous single codon deletion, c.262_264GAG (p.E88del), resulting in the loss of a glutamic acid residue in the low-density lipoprotein receptor type A-like domain. Inserting the codon by site-directed mutagenesis fully restored TCblR function.

  19. Requirement of glycogenolysis for uptake of increased extracellular K+ in astrocytes: potential implications for K+ homeostasis and glycogen usage in brain.

    PubMed

    Xu, Junnan; Song, Dan; Xue, Zhanxia; Gu, Li; Hertz, Leif; Peng, Liang

    2013-03-01

    The importance of astrocytic K(+) uptake for extracellular K(+) ([K(+)](e)) clearance during neuronal stimulation or pathophysiological conditions is increasingly acknowledged. It occurs by preferential stimulation of the astrocytic Na(+),K(+)-ATPase, which has higher K(m) and V(max) values than its neuronal counterpart, at more highly increased [K(+)](e) with additional support of the cotransporter NKCC1. Triggered by a recent DiNuzzo et al. paper, we used administration of the glycogenolysis inhibitor DAB to primary cultures of mouse astrocytes to determine whether K(+) uptake required K(+)-stimulated glycogenolysis. KCl was increased by either 5 mM (stimulating only the Na(+),K(+)-ATPase) or 10 mM (stimulating both transporters) in glucose-containing saline media prepared to become iso-osmotic after the addition. DAB completely inhibited both uptakes, the Na(+),K(+)-ATPase-mediated by preventing Na(+) uptake for stimulation of its intracellular Na(+)-activated site, and the NKCC1-mediated uptake by inhibition of depolarization- and L-channel-mediated Ca(2+) uptake. Drugs inhibiting the signaling pathways involved in either of these processes also abolished K(+) uptake. Assuming similar in vivo characteristics, partly supported by literature data, K(+)-stimulated astrocytic K(+) uptake must discontinue after normalization of extracellular K(+). This will allow Kir1.4-mediated release and reuptake by the less powerful neuronal Na(+),K(+)-ATPase.

  20. Site Construction.

    ERIC Educational Resources Information Center

    Richardson, Eric C.

    1996-01-01

    Presents a guide to planning and building a Web site, with an emphasis on setting up a Web server. Discussion includes hiring a consultant, contracts and payment, assembly of teams, training, development of a business plan, registration of domain name, purchase of hardware and software, local area networks, and types of Internet connection. (JKP)

  1. d-Galactose Uptake by Fenugreek Cotyledons 1

    PubMed Central

    Zambou, Katerina; Spyropoulos, Caroline G.

    1990-01-01

    The uptake of d-galactose was studied in detached fenugreek (Trigonella foenum-graecum L.) cotyledons. Uptake kinetics and treatment with p-chloromercury-benzenesulfonic acid indicated that at low concentrations d-galactose was taken up by a carrier. At higher concentrations a diffusion-like component existed. Proton flux and pH studies, treatment with α-naphthaleneacetic acid, and uptake experiments under water stress conditions suggested that d-galactose was not taken up via H+ contransport. However, d-galactose uptake was under metabolic control. Uptake kinetics under water stress conditions suggested that moderate water stress either increased the Km of the carrier or decreased the Vmax. However, prolonged stress transformed the carrier-mediated uptake into a diffusion uptake transport. The uptake of d-galactose by fenugreek cotyledons was very low before and just after germination, was maximum after 35 hours imbibition, and started decreasing thereafter. The different uptake rates of d-galactose with imbibition times were attributed to the operation of the carrier. At low uptake rates the carrier did not operate. Treatment with cycloheximide suggested that the carrier was synthesized de novo just after germination and stopped operating when all galactomannan hydrolysis was over. Results were discussed in the context of control of endosperm galactomannan hydrolysis by the cotyledons of fenugreek embryo. PMID:16667633

  2. Similarity in microbial amino acid uptake in surface waters of the North and South Atlantic (sub-)tropical gyres

    NASA Astrophysics Data System (ADS)

    Hill, Polly G.; Mary, Isabelle; Purdie, Duncan A.; Zubkov, Mikhail V.

    2011-12-01

    The Earth’s most extensive biomes - the oceanic subtropical gyres - are considered to be expanding with current surface ocean warming. Although it is well established that microbial communities control gyre biogeochemistry, comparisons of their metabolic activities between gyres are limited. In order to estimate metabolic activities including production of microbial communities, the uptake rates of amino acids leucine, methionine and tyrosine at ambient concentrations were estimated in surface waters of the Atlantic Ocean using radioisotopically labelled tracers. Data were acquired during six research cruises covering main oceanic provinces herein termed: North and South Atlantic Gyres, Bermuda Atlantic Time-series Study site (BATS), Equatorial region, and Mauritanian Upwelling (off Cape Blanc). Data were divided between provinces, the extents of which were identified by ocean colour data, in order to achieve provincial mean uptake rates. Leucine and methionine uptake rates did not differ between sampling periods, and were comparable between the North and South subtropical gyres. Furthermore, variation in uptake rates measured throughout the two oligotrophic gyres, where sampling covered ∼4 × 10 6 km 2, was considerably lower than that measured within the Mauritanian Upwelling and Equatorial regions, and even at the BATS site. Tyrosine was generally the slowest of the amino acids to be taken up, however, it was assimilated faster than methionine within the Mauritanian Upwelling region. Thus, we propose that one value for leucine (12.6 ± 3.2 pmol L -1 h -1) and methionine (10.0 ± 3.3 pmol L -1 h -1) uptake could be applied to the oligotrophic subtropical gyres of the Atlantic Ocean. However, with the significantly lower uptake rates observed at the BATS site, we would not advise extrapolation to the Sargasso Sea.

  3. Assessment of producers' response to Salmonella biosecurity issues and uptake of advice on laying hen farms in England and Wales.

    PubMed

    Gosling, R J; Martelli, F; Wintrip, A; Sayers, A R; Wheeler, K; Davies, R H

    2014-01-01

    High standards of biosecurity are known to reduce the risk of disease outbreaks; however, uptake of advice and implementation of biosecurity measures are dependent on many factors. This study assessed the uptake of targeted biosecurity advice by 60 laying hen farms provided during biosecurity audit visits. Advice was provided as bullet point cards focusing on specific areas identified as benefitting from improvement. These covered site entrance, site tidiness, vaccination, boot hygiene, hand hygiene, house tidiness, rodent control, fly control, red mite control and cleaning and disinfection between flocks. Background knowledge of Salmonella and biosecurity and farmers' willingness and intent to implement additional measures were assessed. About 50% of the principal decision-makers had basic background knowledge of Salmonella, with 22% considered well informed; almost all agreed that biosecurity could impact on Salmonella control and many appeared willing to implement additional biosecurity measures. Sixty-three per cent of study farms were categorised using the Defra Farmer Segmentation Model as Modern Family Businesses (MFBs), with 7-11% of farms being categorised as Custodian, Lifestyle Choice, Pragmatist or Challenged Enterprise; however, categorisation, did not determine uptake of advice. The most frequently used advice cards were boot hygiene, red mite control, hand hygiene, site entrance and cleaning and disinfection; uptake of advice ranged from 54 to 80% depending on the advice card. Uptake of advice by the farmers was encouraging, especially considering it was being provided by people other than their usual source of biosecurity information. Those who did not implement the recommended measures cited cost, difficulty of enforcement and practicality as the main reasons. However, the positive uptake of advice and implementation of recommended measures by many farmers demonstrates that targeted advice, discussed face to face with farmers, on a small number of

  4. Assessment of producers' response to Salmonella biosecurity issues and uptake of advice on laying hen farms in England and Wales.

    PubMed

    Gosling, R J; Martelli, F; Wintrip, A; Sayers, A R; Wheeler, K; Davies, R H

    2014-01-01

    High standards of biosecurity are known to reduce the risk of disease outbreaks; however, uptake of advice and implementation of biosecurity measures are dependent on many factors. This study assessed the uptake of targeted biosecurity advice by 60 laying hen farms provided during biosecurity audit visits. Advice was provided as bullet point cards focusing on specific areas identified as benefitting from improvement. These covered site entrance, site tidiness, vaccination, boot hygiene, hand hygiene, house tidiness, rodent control, fly control, red mite control and cleaning and disinfection between flocks. Background knowledge of Salmonella and biosecurity and farmers' willingness and intent to implement additional measures were assessed. About 50% of the principal decision-makers had basic background knowledge of Salmonella, with 22% considered well informed; almost all agreed that biosecurity could impact on Salmonella control and many appeared willing to implement additional biosecurity measures. Sixty-three per cent of study farms were categorised using the Defra Farmer Segmentation Model as Modern Family Businesses (MFBs), with 7-11% of farms being categorised as Custodian, Lifestyle Choice, Pragmatist or Challenged Enterprise; however, categorisation, did not determine uptake of advice. The most frequently used advice cards were boot hygiene, red mite control, hand hygiene, site entrance and cleaning and disinfection; uptake of advice ranged from 54 to 80% depending on the advice card. Uptake of advice by the farmers was encouraging, especially considering it was being provided by people other than their usual source of biosecurity information. Those who did not implement the recommended measures cited cost, difficulty of enforcement and practicality as the main reasons. However, the positive uptake of advice and implementation of recommended measures by many farmers demonstrates that targeted advice, discussed face to face with farmers, on a small number of

  5. Chemical hydrophobicity and uptake by plant roots.

    PubMed

    Dettenmaier, Erik M; Doucette, William J; Bugbee, Bruce

    2009-01-15

    The transpiration stream concentration factor (TSCF), the ratio between a compound's concentration in the xylem to that in the solution adjacent to the roots, is commonly used to describe the relative ability of an organic compound to be passively transported from root to shoot. Widely cited bell-shaped curves relating TSCFto the octanol/water partition coefficient (log Kow) imply that significant root uptake and transfer into shoot tissues occurs only for compounds falling within an intermediate hydrophobicity range. However, recent laboratory and field data for relatively water soluble compounds such as sulfolane, methyl tert-butyl ether (MTBE), and 1,4-dioxane suggest that these relationships are not universally applicable, especiallyfor nonionizable, highly polar, water soluble organics. To re-evaluate the relationship between root uptake and chemical hydrophobicity, TSCFs were measured for 25 organic chemicals ranging in log Kow from -0.8 to 5 using a pressure chamber technique. Using the TSCF values measured in this study, a new empirical relationship between TSCF (0 and 1) and log Kow (-0.8 to 5) is presented that indicates that nonionizable, polar, highly water soluble organic compounds are most likely to be taken up by plant roots and translocated to shoot tissue.

  6. Pharmacokinetics of sevoflurane uptake into the brain.

    PubMed

    Turner, M J; McCulloch, T J; Kennedy, R R; Baker, A B

    2004-12-01

    Two recent studies have examined the pharmacokinetics of sevoflurane in adults. Lu et al.(Pharmacokinetics of sevoflurane uptake into the brain and body, Anaesthesia 2003; 58: 951-6) observed that jugular bulb sevoflurane concentration initially rose unexpectedly rapidly and then approached arterial concentrations unexpectedly slowly, suggesting that a blood-brain diffusion barrier exists. They also observed a large alveolar-arterial sevoflurane gradient, suggesting that an alveolar-arterial diffusion barrier exists. Nakamura et al. (Predicted sevoflurane partial pressure in the brain with an uptake and distribution model: Comparison with the measured value in internal jugular vein blood. Journal of Clinical Monitoring and Computing 1999; 15: 299-305) found no diffusion barriers. We used a computer model to analyse both data sets and show that the observations of Lu et al. can be explained by contamination of jugular samples with extracerebral blood. It is possible that the alveolar-arterial gradients observed by Lu et al. are due to discrepancies in conversions between blood concentrations and gas partial pressures. Our study suggests that there is no blood-brain diffusion barrier for sevoflurane and that the data of Lu et al. must be interpreted with caution.

  7. Liver uptake of biguanides in rats.

    PubMed

    Sogame, Yoshihisa; Kitamura, Atsushi; Yabuki, Masashi; Komuro, Setsuko

    2011-09-01

    Metformin is an oral antihyperglycaemic agent widely used in the management of non-insulin-dependent diabetes mellitus. The liver is the primary target, metformin being taken up into human and rat hepatocytes via an active transport mechanism. The present study was designed to compare hepatic uptake of two biguanides, metformin and phenformin, in vitro and in vivo. In in vitro experiments, performed using rat cryopreserved hepatocytes, phenformin exhibited a much higher affinity and transport than metformin, with marked differences in kinetics. The K(m) values for metformin and phenformin were 404 and 5.17μM, respectively, with CLint (V(max)/K(m)) values 1.58μl/min per 10(6) cells and 34.7μl/min per 10(6) cells. In in vivo experiments, when (14)C-metformin and (14)C-phenformin were given orally to male rats at a dose of 50mg/kg, the liver concentrations of radioactivity at 0.5 hour after dosing were 21.5μg eq./g with metformin but 147.1μg eq./g for phenformin, ratios of liver to plasma concentrations being 4.2 and 61.3, respectively. In conclusion, the results suggest that uptake of biguanides by rat hepatocytes is in line with the liver distribution found in vivo, phenformin being more efficiently taken up by liver than metformin after oral administration.

  8. Freehand SPECT in low uptake situations

    NASA Astrophysics Data System (ADS)

    Lasser, Tobias; Ziegler, Sibylle I.; Navab, Nassir

    2011-03-01

    3D functional imaging in the operating room can be extremely useful for some procedures like SLN mapping or SLN biopsies. Freehand SPECT is an example of such an imaging modality, combining manually scanned, hand-held 1D gamma detectors with spatial positioning systems in order to reconstruct localized 3D SPECT images, for example in the breast or neck region. Standard series expansion methods are applied together with custom physical models of the acquisition process and custom filtering procedures to perform 3D tomographic reconstruction from sparse, limited-angle and irregularly sampled data. A Freehand SPECT system can easily be assembled on a mobile cart suitable for use in the operating room. This work addresses in particular the problem of objects with low uptake (like sentinel lymph nodes), where reconstruction tends to be difficult due to low signal to noise ratio. In a neck-like phantom study, we show that four simulated nodes of 250 microliter volume with 0.06% respectively 0.03% uptake of a virtual 70MBq injection of Tc99m (the typical activity for SLN procedures at our hospital) in a background of water can be reconstructed successfully using careful filtering procedures in the reconstruction pipeline. Ten independent Freehand SPECT scans of the phantom were performed by several different operators, with an average scan duration of 5.1 minutes. The resulting reconstructions show an average spatial accuracy within voxel dimensions (2.5mm) compared to CT and exhibit correct relative quantification.

  9. Imaging neurotransmitter uptake and depletion in astrocytes

    SciTech Connect

    Tan, W. |; Haydon, P.G.; Yeung, E.S.

    1997-08-01

    An ultraviolet (UV) laser-based optical microscope and charge-coupled device (CCD) detection system was used to obtain chemical images of biological cells. Subcellular structures can be easily seen in both optical and fluorescence images. Laser-induced native fluorescence detection provides high sensitivity and low limits of detection, and it does not require coupling to fluorescent dyes. We were able to quantitatively monitor serotonin that has been taken up into and released from individual astrocytes on the basis of its native fluorescence. Different regions of the cells took up different amounts of serotonin with a variety of uptake kinetics. Similarly, we observed different serotonin depletion dynamics in different astrocyte regions. There were also some astrocyte areas where no serotonin uptake or depletion was observed. Potential applications include the mapping of other biogenic species in cells as well as the ability to image their release from specific regions of cells in response to external stimuli. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  10. Pathways of Arsenic Uptake and Efflux

    PubMed Central

    Yang, Hung-Chi; Fu, Hsueh-Liang; Lin, Yung-Feng; Rosen, Barry P.

    2015-01-01

    Arsenic is the most prevalent environmental toxic substance and ranks first on the U.S. Environmental Protection Agency’s Superfund List. Arsenic is a carcinogen and a causative agent of numerous human diseases. Paradoxically arsenic is used as a chemotherapeutic agent for treatment of acute promyelocytic leukemia. Inorganic arsenic has two biological important oxidation states: As(V) (arsenate) and As(III) (arsenite). Arsenic uptake is adventitious because the arsenate and arsenite are chemically similar to required nutrients. Arsenate resembles phosphate and is a competitive inhibitor of many phosphate-utilizing enzymes. Arsenate is taken up by phosphate transport systems. In contrast, at physiological pH, the form of arsenite is As(OH)3, which resembles organic molecules such as glycerol. Consequently, arsenite is taken into cells by aquaglyceroporin channels. Arsenic efflux systems are found in nearly every organism and evolved to rid cells of this toxic metalloid. These efflux systems include members of the multidrug resistance protein family and the bacterial exchangers Acr3 and ArsB. ArsB can also be a subunit of the ArsAB As(III)-translocating ATPase, an ATP-driven efflux pump. The ArsD metallochaperone binds cytosolic As(III) and transfers it to the ArsA subunit of the efflux pump. Knowledge of the pathways and transporters for arsenic uptake and efflux is essential for understanding its toxicity and carcinogenicity and for rational design of cancer chemotherapeutic drugs. PMID:23046656

  11. Mitochondrial calcium uptake capacity modulates neocortical excitability

    PubMed Central

    Sanganahalli, Basavaraju G; Herman, Peter; Hyder, Fahmeed; Kannurpatti, Sridhar S

    2013-01-01

    Local calcium (Ca2+) changes regulate central nervous system metabolism and communication integrated by subcellular processes including mitochondrial Ca2+ uptake. Mitochondria take up Ca2+ through the calcium uniporter (mCU) aided by cytoplasmic microdomains of high Ca2+. Known only in vitro, the in vivo impact of mCU activity may reveal Ca2+-mediated roles of mitochondria in brain signaling and metabolism. From in vitro studies of mitochondrial Ca2+ sequestration and cycling in various cell types of the central nervous system, we evaluated ranges of spontaneous and activity-induced Ca2+ distributions in multiple subcellular compartments in vivo. We hypothesized that inhibiting (or enhancing) mCU activity would attenuate (or augment) cortical neuronal activity as well as activity-induced hemodynamic responses in an overall cytoplasmic and mitochondrial Ca2+-dependent manner. Spontaneous and sensory-evoked cortical activities were measured by extracellular electrophysiology complemented with dynamic mapping of blood oxygen level dependence and cerebral blood flow. Calcium uniporter activity was inhibited and enhanced pharmacologically, and its impact on the multimodal measures were analyzed in an integrated manner. Ru360, an mCU inhibitor, reduced all stimulus-evoked responses, whereas Kaempferol, an mCU enhancer, augmented all evoked responses. Collectively, the results confirm aforementioned hypotheses and support the Ca2+ uptake-mediated integrative role of in vivo mitochondria on neocortical activity. PMID:23591650

  12. Uptake of Latex Particles by Blood Platelets

    PubMed Central

    White, James G.

    1972-01-01

    The incorporation of large particulates by blood platelets is considered identical to the ingestion of bacteria by neutrophils, and is referred to as platelet phagocytosis. However, bacteria enter neutrophils in sealed vacuoles derived from the cell wall, and products deposited in the vacuoles during neutrophil degranulation are confined almost exclusively to the phagolysosomes. Products released from platelet storage organelles after uptake of foreign particles, on the other hand, are extruded to the cell exterior. The basis for this unusual difference in the phagocytic response of platelets and neutrophils has been sought in the present investigation. Combined electron microscopic and cytechemical study of platelet-latexspherule interaction revealed that platelets do not phagocytize in the usual sense. Most of the latex particles observed in platelets were lodged in channels of the open canalicular system. Channels which contained latex did not pinch off to form sealed phagocytic vacuoles, but remained open. An electron-dense tracer, lanthanum nitrate, was able to penetrate into the channels and outline the ingested latex particles. Therefore, platelets do not phagocytize latex, but sequester the spherules in preformed membranous invaginations. The persistence of open channel communication with the exterior after latex uptake may explain why platelets extrude secretory products, rather than confine them to phagolysosomes. ImagesFig 4Fig 1Fig 5Fig 2Fig 6Fig 3 PMID:5086899

  13. Iodide uptake by negatively charged clay interlayers?

    PubMed

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species.

  14. Vaccine production, distribution, access, and uptake.

    PubMed

    Smith, Jon; Lipsitch, Marc; Almond, Jeffrey W

    2011-07-30

    For human vaccines to be available on a global scale, complex production methods, meticulous quality control, and reliable distribution channels are needed to ensure that the products are potent and effective at the point of use. The technologies used to manufacture different types of vaccines can strongly affect vaccine cost, ease of industrial scale-up, stability, and, ultimately, worldwide availability. The complexity of manufacturing is compounded by the need for different formulations in different countries and age-groups. Reliable vaccine production in appropriate quantities and at affordable prices is the cornerstone of developing global vaccination policies. However, to ensure optimum access and uptake, strong partnerships are needed between private manufacturers, regulatory authorities, and national and international public health services. For vaccines whose supply is insufficient to meet demand, prioritisation of target groups can increase the effect of these vaccines. In this report, we draw from our experience of vaccine development and focus on influenza vaccines as an example to consider production, distribution, access, and other factors that affect vaccine uptake and population-level effectiveness. PMID:21664680

  15. Microbiology and Moisture Uptake of Desert Soils

    NASA Astrophysics Data System (ADS)

    Kress, M. E.; Bryant, E. P.; Morgan, S. W.; Rech, S.; McKay, C. P.

    2005-12-01

    We have initiated an interdisciplinary study of the microbiology and water content of desert soils to better understand microbial activity in extreme arid environments. Water is the one constituent that no organism can live without; nevertheless, there are places on Earth with an annual rainfall near zero that do support microbial ecosystems. These hyperarid deserts (e.g. Atacama and the Antarctic Dry Valleys) are the closest terrestrial analogs to Mars, which is the subject of future exploration motivated by the search for life beyond Earth. We are modeling the moisture uptake by soils in hyperarid environments to quantify the environmental constraints that regulate the survival and growth of micro-organisms. Together with the studies of moisture uptake, we are also characterizing the microbial population in these soils using molecular and culturing methods. We are in the process of extracting DNA from these soils using MoBio extraction kits. This DNA will be used as a template to amplify bacterial and eukaryotic ribosomal DNA to determine the diversity of the microbial population. We also have been attempting to determine the density of organisms by culturing on one-half strength R2A agar. The long-range goal of this research is to identify special adaptations of terrestrial life that allow them to inhabit extreme arid environments, while simultaneously quantifying the environmental parameters that enforce limits on these organisms' growth and survival.

  16. Pathways of arsenic uptake and efflux.

    PubMed

    Yang, Hung-Chi; Fu, Hsueh-Liang; Lin, Yung-Feng; Rosen, Barry P

    2012-01-01

    Arsenic is the most prevalent environmental toxic substance and ranks first on the U.S. Environmental Protection Agency's Superfund List. Arsenic is a carcinogen and a causative agent of numerous human diseases. Paradoxically arsenic is used as a chemotherapeutic agent for treatment of acute promyelocytic leukemia. Inorganic arsenic has two biological important oxidation states: As(V) (arsenate) and As(III) (arsenite). Arsenic uptake is adventitious because the arsenate and arsenite are chemically similar to required nutrients. Arsenate resembles phosphate and is a competitive inhibitor of many phosphate-utilizing enzymes. Arsenate is taken up by phosphate transport systems. In contrast, at physiological pH, the form of arsenite is As(OH)(3), which resembles organic molecules such as glycerol. Consequently, arsenite is taken into cells by aquaglyceroporin channels. Arsenic efflux systems are found in nearly every organism and evolved to rid cells of this toxic metalloid. These efflux systems include members of the multidrug resistance protein family and the bacterial exchangers Acr3 and ArsB. ArsB can also be a subunit of the ArsAB As(III)-translocating ATPase, an ATP-driven efflux pump. The ArsD metallochaperone binds cytosolic As(III) and transfers it to the ArsA subunit of the efflux pump. Knowledge of the pathways and transporters for arsenic uptake and efflux is essential for understanding its toxicity and carcinogenicity and for rational design of cancer chemotherapeutic drugs.

  17. Mitochondrial calcium uptake capacity modulates neocortical excitability.

    PubMed

    Sanganahalli, Basavaraju G; Herman, Peter; Hyder, Fahmeed; Kannurpatti, Sridhar S

    2013-07-01

    Local calcium (Ca(2+)) changes regulate central nervous system metabolism and communication integrated by subcellular processes including mitochondrial Ca(2+) uptake. Mitochondria take up Ca(2+) through the calcium uniporter (mCU) aided by cytoplasmic microdomains of high Ca(2+). Known only in vitro, the in vivo impact of mCU activity may reveal Ca(2+)-mediated roles of mitochondria in brain signaling and metabolism. From in vitro studies of mitochondrial Ca(2+) sequestration and cycling in various cell types of the central nervous system, we evaluated ranges of spontaneous and activity-induced Ca(2+) distributions in multiple subcellular compartments in vivo. We hypothesized that inhibiting (or enhancing) mCU activity would attenuate (or augment) cortical neuronal activity as well as activity-induced hemodynamic responses in an overall cytoplasmic and mitochondrial Ca(2+)-dependent manner. Spontaneous and sensory-evoked cortical activities were measured by extracellular electrophysiology complemented with dynamic mapping of blood oxygen level dependence and cerebral blood flow. Calcium uniporter activity was inhibited and enhanced pharmacologically, and its impact on the multimodal measures were analyzed in an integrated manner. Ru360, an mCU inhibitor, reduced all stimulus-evoked responses, whereas Kaempferol, an mCU enhancer, augmented all evoked responses. Collectively, the results confirm aforementioned hypotheses and support the Ca(2+) uptake-mediated integrative role of in vivo mitochondria on neocortical activity.

  18. Abiotic uptake of gases by organic soils

    NASA Astrophysics Data System (ADS)

    Smagin, A. V.

    2007-12-01

    Methodological and experimental studies of the abiotic uptake of gaseous substances by organic soils were performed. The static adsorption method of closed vessels for assessing the interaction of gases with the solid and liquid soil phases and the dynamic method of determining the sorption isotherms of gases by soils were analyzed. The theoretical substantiation of the methods and their practical implementations on the basis of a PGA-7 portable gas analyzer (Russia) were considered. Good agreement between the equilibrium sorption isotherms of the gases and the Langmuir model was revealed; for the real ranges of natural gas concentrations, this model can be reduced to the linear Henry equation. The limit values of the gas sorption (Langmuir monolayer capacity) are typical for dry samples; they vary from 670 4000 g/m3 for methane and oxygen to 20 000 25 000 g/m3 for carbon dioxide. The linear distribution coefficients of gases between the solid and gas phases of organic soils (Henry constants) are 8 18 units for poorly sorbed gases (O2, CH4) and 40 60 units for CO2. The kinetics of the chemicophysical uptake of gases by the soil studied is linear in character and obeys the relaxation kinetic model of the first order with the corresponding relaxation constants, which vary from 1 h -1 in wet samples to 10 h -1 in dry samples.

  19. Iron uptake and transport across physiological barriers.

    PubMed

    Duck, Kari A; Connor, James R

    2016-08-01

    Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron's function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood-brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers. PMID:27457588

  20. Uptake and partitioning of zinc in Lemnaceae.

    PubMed

    Lahive, Elma; O'Callaghan, Michael J A; Jansen, Marcel A K; O'Halloran, John

    2011-11-01

    Macrophytes provide food and shelter for aquatic invertebrates and fish, while also acting as reservoirs for nutrients and trace elements. Zinc accumulation has been reported for various Lemnaceae species. However, comparative accumulation across species and the link between zinc accumulation and toxicity are poorly understood. Morphological distribution and cellular storage, in either bound or soluble form, are important for zinc tolerance. This study shows differences in the uptake and accumulation of zinc by three duckweed species. Landoltia punctata and Lemna minor generally accumulated more zinc than Lemna gibba. L. minor, but not L. gibba or L. punctata, accumulated greater concentrations of zinc in roots compared to fronds when exposed to high levels of zinc. The proportion of zinc stored in the bound form relative to the soluble-form was higher in L. minor. L. punctata accumulated greater concentrations of zinc in fronds compared to roots and increased the proportion of zinc it stored in the soluble form, when exposed to high zinc levels. L. gibba is the only species that significantly accumulated zinc at low concentrations, and was zinc-sensitive. Overall, internal zinc concentrations showed no consistent correlation with toxic effect. We conclude that relationships between zinc toxicity and uptake and accumulation are species specific reflecting, among others, zinc distribution and storage. Differences in zinc distribution and storage are also likely to have implications for zinc bioavailability and trophic mobility. PMID:21755349

  1. Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

  2. Lead uptake, toxicity, and detoxification in plants.

    PubMed

    Pourrut, Bertrand; Shahid, Muhammad; Dumat, Camille; Winterton, Peter; Pinelli, Eric

    2011-01-01

    Lead has gained considerable attention as a persistent toxic pollutant of concern,partly because it has been prominent in the debate concerning the growing anthropogenic pressure on the environment. The purpose of this review is to describe how plants take lead up and to link such uptake to the ecotoxicity of lead in plants.Moreover, we address the mechanisms by which plants or plant systems detoxify lead.Lead has many interesting physico-chemical properties that make it a very useful heavy metal. Indeed, lead has been used by people since the dawn of civilization.Industrialization, urbanization, mining, and many other anthropogenic activities have resulted in the redistribution of lead from the earth's crust to the soil and to the environment.Lead forms various complexes with soil components, and only a small fraction of the lead present as these complexes in the soil solution are phyto available. Despite its lack of essential function in plants, lead is absorbed by them mainly through the roots from soil solution and thereby may enter the food chain. The absorption of lead by roots occurs via the apoplastic pathway or via Ca2+-permeable channels.The behavior of lead in soil, and uptake by plants, is controlled by its speciation and by the soil pH, soil particle size, cation-exchange capacity, root surface area,root exudation, and degree of mycorrhizal transpiration. After uptake, lead primarily accumulates in root cells, because of the blockage by Casparian strips within the endodermis. Lead is also trapped by the negative charges that exist on roots' cell walls.Excessive lead accumulation in plant tissue impairs various morphological, physiological, and biochemical functions in plants, either directly or indirectly, and induces a range of deleterious effects. It causes phytotoxicity by changing cell membrane permeability, by reacting with active groups of different enzymes involved in plant metabolism and by reacting with the phosphate groups of ADP or ATP

  3. A hierarchical examination of methane uptake: field patterns, lab physiology, community composition and biogeography

    NASA Astrophysics Data System (ADS)

    von Fischer, J. C.; Koyama, A.; Johnson, N. G.; Webb, C. T.

    2015-12-01

    Scaling problems abound in biogeochemistry. At the finest scale, soil microbes experience habitats and environmental changes that affect the chemical transformations of interest. We collect the DNA of these organisms from sites across landscapes and note differences in who is there, and we seek to evaluate why group membership changes in space (biogeography) and why activity rates change over time (physiology). The goal of efforts at finer scales is often to better predict patterns at larger scales. We conducted such a hierarchical examination of methane uptake in the Great Plains grasslands of North America, gathering data from 22 plots at 8 field locations, scattered from South Dakota to New Mexico and Colorado to Kansas. Our work provides insight into methanotroph biogeochemistry at all of these scales. For example, we found that methane uptake rates vary mostly due to the methanotroph activity, and less so due to diffusivity. A combination of field and lab observations reveal that methanotroph communities differ in their sensitivity to soil moisture and to ammonium (an inhibitor of methanotrophy). Examination of methanotroph community composition reveals tantalizing patterns in composition, dominance and richness across sites, that appears to be structured by patterns of precipitation and soil texture. We anticipate that greater synthesis of these hierarchical findings will paint a richer picture of methanotroph life and enable improved prediction of methane uptake at regional scales.

  4. [The peroperative isotopic location of osteoid osteomas and other lesions exhibiting increased uptake on scintigraphy].

    PubMed

    Augereau, B; Wioland, M; De Labriolle-Vaylet, C; Padovani, J P; Martin, T; Verneret, C; Apoil, A; Milhaud, G

    1988-01-01

    The technique, advantages and pitfalls of the isotopic localization and control during operation in orthopaedic surgery were evaluated throughout 28 interventions on lesions, which exhibited an increased uptake of a radioactive bone-seeker: the dimethyl-aminodiphosphonate, provisionally designated SF44 (Laboratoires Solabco, Coutras, France). For bone scanning, following the injection of this radiopharmaceutical that increased by 25% the lesion to normal bone ratio compared to the data for the diphosphonates in current use, the localization of lesions at surgical sites was carried out with the use of a sterilisable small radiation probe of a circular cross section 2 mm in diameter (Quartz et Silice, Paris, France). The probe was connected to a portable electronic device that converted the rates of radioactive disintegration into an acoustic signal, which increased with increasing radioactivity (Novelec, Meylan, France). The method was atraumatic and has proved to be useful at various times of the operation. More often, it was used to locate the lesion on the exposed bone. It enabled monitoring the progress of excisions and allowed to shorten their dimensions. The method was of great value at the end of the intervention for ensuring a complete excision as indicated by the lack of any residual focus of increased uptake detectable on the periphery of the operative site. Isotopic control during an operation is fully efficient to locate osteoid osteomas and other circumscribed lesions of the skeleton that give rise to an increased uptake of radioactivity.

  5. A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions

    NASA Astrophysics Data System (ADS)

    Pang, Jiandong; Jiang, Feilong; Wu, Mingyan; Liu, Caiping; Su, Kongzhao; Lu, Weigang; Yuan, Daqiang; Hong, Maochun

    2015-06-01

    Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm3 (STP) g-1 and the second-highest volumetric uptake of 196 cm3 (STP) cm-3 at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (~200 cm3 (STP) g-1). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption-desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake.

  6. A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions

    PubMed Central

    Pang, Jiandong; Jiang, Feilong; Wu, Mingyan; Liu, Caiping; Su, Kongzhao; Lu, Weigang; Yuan, Daqiang; Hong, Maochun

    2015-01-01

    Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm3 (STP) g−1 and the second-highest volumetric uptake of 196 cm3 (STP) cm−3 at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm3 (STP) g−1). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption–desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake. PMID:26123775

  7. Elemental uptake and distribution of nutrients in avocado mesocarp and the impact of soil quality.

    PubMed

    Reddy, Mageshni; Moodley, Roshila; Jonnalagadda, Sreekanth B

    2014-07-01

    The distribution of 14 elements (both essential and non-essential) in the Hass and Fuerte cultivars of avocados grown at six different sites in KwaZulu-Natal, South Africa, was investigated. Soils from the different sites were concurrently analysed for elemental concentration (both total and exchangeable), pH, organic matter and cation exchange capacity. In both varieties of the fruit, concentrations of the elements Cd, Co, Cr, Pb and Se were extremely low with the other elements being in decreasing order of Mg > Ca > Fe > Al > Zn > Mn > Cu > Ni > As. Nutritionally, avocados were found to be a good dietary source of the micronutrients Cu and Mn. In soil, Pb concentrations indicated enrichment (positive geoaccumuluation indices) but this did not influence uptake of the metal by the plant. Statistical analysis was done to evaluate the impact of soil quality parameters on the nutrient composition of the fruits. This analysis indicated the prevalence of complex metal interactions at the soil-plant interface that influenced their uptake by the plant. However, the plant invariably controlled metal uptake according to metabolic needs as evidenced by their accumulation and exclusion.

  8. Can Canopy Uptake Influence Nitrogen Acquisition and Allocation by Trees?

    NASA Astrophysics Data System (ADS)

    Nair, Richard; Perks, Mike; Mencuccini, Maurizio

    2015-04-01

    Nitrogen (N) fertilization due to atmospheric deposition of anthropogenic nitrogen (NDEP) may explain some of the net carbon (C) sink (0.6-0.7 Pg y-1) in temperate forests, but estimates of the additional C uptake due to atmospheric N additions (ΔCΔN) can vary by over an order of magnitude (~ 5 to 200 ΔCΔN). High estimates from several recent studies [e.g. Magnani (2007), Nature 447 848-850], deriving ΔCΔN from regional correlations between NDEP and measures of C uptake (such as eddy covariance -derived net ecosystem production, or forest inventory data) contradict estimates from other studies of 15N tracer applications added as fertilizer to the forest floor. A strong ΔCΔN effect requires nitrogen to be efficiently acquired by trees and allocated to high C:N, long-lived woody tissues, but these isotope experiments typically report relatively little (~ 20 %) of 15N added is found above-ground, with < 5 % of the total 15N applied found in wood. Consequently the high correlation-derived ΔCΔN estimates are often attributed to co-variation with other factors across the range of sites investigated. However 15N-fertilization treatments often impose considerably higher total N loads than ambient NDEP and almost exclusively only apply mineral 15N treatments to the soil, often in a limited number of treatment events over relatively short periods of time. Excessive N deposition loads can induce negative physiological effects and limit the resulting ΔCΔN observed, and applying treatments to the soil may ignore the importance of canopy nitrogen uptake in overall forest nutrition. As canopies can directly take up nitrogen, the chronic, (relatively) low levels of ambient NDEP inputs from pollution may be acquired without some of the effects of heavy N loads, obtaining this N before it reaches the soil, and allowing canopies to substitute for, or supplement, edaphic N nutrition. The strength of this effect depends on how much N uptake can occur across the canopy under

  9. Estimation of stream nutrient uptake from nutrient addition experiments

    SciTech Connect

    Payn, Robert

    2005-09-01

    Nutrient uptake in streams is often quantified by determining nutrient uptake length. However, current methods for measuring nutrient uptake length are often impractical, expensive, or demonstrably incorrect. We have developed a new method to estimate ambient nutrient uptake lengths using field experiments involving several levels of nutrient addition. Data analysis involves plotting nutrient addition uptake lengths versus added concentration and extrapolating to the negative ambient concentration. This method is relatively easy, inexpensive, and based on sound theoretical development. It is more accurate than the commonly used method involving a single nutrient addition. The utility of the method is supported by field studies directly comparing our new method with isotopic tracer methods for determining uptake lengths of phosphorus, ammonium, and nitrate. Our method also provides parameters for comparing potential nutrient limitation among streams.

  10. Uptake and incorporation of pyrimidines in Euglena gracilis.

    PubMed

    Wasternack, C H

    1976-08-01

    In photoorganotrophically grown cells of Euglena gracilis the uptake and incorporation degree of 12 different pyrimidines were tested. The rate of uptake of pyrimidines has distinct maxima in the late log phase and in the stationary phase of cell multiplication. The kinetics of uptake are linear in the first 2 h, do not show saturation at various concentrations and increase with the concetrations. No accumulation of the pyrimidines at various concentrations could be observed in the first 2 h of incubation. Membrane inhibitors as uranyl acetate inhibit the uptake of the reference substance alpha-AIB, which is wellknown transported by an active transport mechanism, but have no effect on uptake rate of uracil and cytosine. It could not be observed an energy requirement tested in temperature dependence and with electron transport inhibitors. Uptake of uridine, uracil, barbituric acid and alpha-AIB is inhibited by cycloheximide in a different manner after 5 - 10 min.

  11. Effect of raw humus under two adult Scots pine stands on ectomycorrhization, nutritional status, nitrogen uptake, phosphorus uptake and growth of Pinus sylvestris seedlings.

    PubMed

    Schulz, Horst; Schäfer, Tina; Storbeck, Veronika; Härtling, Sigrid; Rudloff, Renate; Köck, Margret; Buscot, François

    2012-01-01

    Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth.

  12. ars1, an Arabidopsis mutant exhibiting increased tolerance to arsenate and increased phosphate uptake.

    PubMed

    Lee, David A; Chen, Alice; Schroeder, Julian I

    2003-09-01

    Arsenic is one of the most toxic pollutants at contaminated sites, yet little is known about the mechanisms by which certain plants survive exposure to high arsenic levels. To gain insight into the mechanisms of arsenic tolerance in plants, we developed a genetic screen to isolate Arabidopsis thaliana mutants with altered tolerance to arsenic. We report here on the isolation of a mutant arsenic resisant 1 (ars1) with increased tolerance to arsenate. ars1 germinates and develops under conditions that completely inhibit growth of wild-type plants and shows a semi-dominant arsenic resistance phenotype. ars1 accumulates levels of arsenic similar to that accumulated by wild-type plants, suggesting that ars1 plants have an increased ability to detoxify arsenate. However, ars1 plants produce phytochelatin levels similar to levels produced by the wild type, and the enhanced resistance of ars1 is not abolished by the gamma-glutamylcysteine synthetase inhibitor l-buthionine sulfoxime (BSO). Furthermore, ars1 plants do not show resistance to arsenite or other toxic metals such as cadmium and chromium. However, ars1 plants do show a higher rate of phosphate uptake than that shown by wild-type plants, and wild-type plants grown with an excess of phosphate show increased tolerance to arsenate. Traditional models of arsenate tolerance in plants are based on the suppression of phosphate uptake pathways and consequently on the reduced uptake of arsenate. Our data suggest that arsenate tolerance in ars1 could be due to a new mechanism mediated by increased phosphate uptake in ars1. Models discussing how increased phosphate uptake could contribute to arsenate tolerance are discussed.

  13. Uptake of acetylene on cosmic dust and production of benzene in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria L.; James, Alexander D.; Sánchez, Juan Diego Carrillo; Mangan, Thomas P.; Willacy, Karen; Poppe, Andrew R.; Plane, John M. C.

    2016-11-01

    A low-temperature flow tube and ultra-high vacuum apparatus were used to explore the uptake and heterogeneous chemistry of acetylene (C2H2) on cosmic dust analogues over the temperature range encountered in Titan's atmosphere below 600 km. The uptake coefficient, γ, was measured at 181 K to be (1.6 ± 0.4) × 10-4, (1.9 ± 0.4) × 10-4 and (1.5 ± 0.4) × 10-4 for the uptake of C2H2 on Mg2SiO4, MgFeSiO4 and Fe2SiO4, respectively, indicating that γ is independent of Mg or Fe active sites. The uptake of C2H2 was also measured on SiO2 and SiC as analogues for meteoric smoke particles in Titan's atmosphere, but was found to be below the detection limit (γ < 6 × 10-8 and < 4 × 10-7, respectively). The rate of cyclo-trimerization of C2H2 to C6H6 was found to be 2.6 × 10-5 exp(-741/T) s-1, with an uncertainty ranging from ± 27 % at 115 K to ± 49 % at 181 K. A chemical ablation model was used to show that the bulk of cosmic dust particles (radius 0.02-10 μm) entering Titan's atmosphere do not ablate (< 1% mass loss through sputtering), thereby providing a significant surface for heterogeneous chemistry. A 1D model of dust sedimentation shows that the production of C6H6via uptake of C2H2 on cosmic dust, followed by cyclo-trimerization and desorption, is probably competitive with gas-phase production of C6H6 between 80 and 120 km.

  14. Global 3D Imaging of Yersinia ruckeri Bacterin Uptake in Rainbow Trout Fry

    PubMed Central

    Ohtani, Maki; Villumsen, Kasper Rømer; Koppang, Erling Olaf; Raida, Martin Kristian

    2015-01-01

    Yersinia ruckeri is the causative agent of enteric redmouth disease (ERM) in rainbow trout, and the first commercially available fish vaccine was an immersion vaccine against ERM consisting of Y. ruckeri bacterin. The ERM immersion vaccine has been successfully used in aquaculture farming of salmonids for more than 35 years. The gills and the gastrointestinal (GI) tract are believed to be the portals of antigen uptake during waterborne vaccination against ERM; however, the actual sites of bacterin uptake are only partly understood. In order to obtain insight into bacterin uptake during waterborne vaccination, optical projection tomography (OPT) together with immunohistochemistry (IHC) was applied to visualize bacterin uptake and processing in whole rainbow trout fry. Visualization by OPT revealed that the bacterin was initially taken up via gill lamellae from within 30 seconds post vaccination. Later, bacterin uptake was detected on other mucosal surfaces such as skin and olfactory bulb from 5 to 30 minutes post vaccination. The GI tract was found to be filled with a complex of bacterin and mucus at 3 hours post vaccination and the bacterin remained in the GI tract for at least 24 hours. Large amounts of bacterin were present in the blood, and an accumulation of bacterin was found in filtering lymphoid organs such as spleen and trunk kidney where the bacterin accumulates 24 hours post vaccination as demonstrated by OPT and IHC. These results suggest that bacterin is taken up via the gill epithelium in the earliest phases of the bath exposure and from the GI tract in the later phase. The bacterin then enters the blood circulatory system, after which it is filtered by spleen and trunk kidney, before finally accumulating in lymphoid organs where adaptive immunity against ERM is likely to develop. PMID:25658600

  15. Uptake of proline by the scutellum of germinating barley grain

    SciTech Connect

    Vaeisaenen, E.; Sopanen, T.

    1986-04-01

    Scutella separated from germinating grains of barley (Hordeum vulgare L. cv Himalaya) took up 1 millimolar L-(/sup 14/C)proline at an initial rate of about 6.5 micromoles gram/sup -1/ fresh weight hour/sup -1/ (pH 5, 30/sup 0/C). The uptake had a pH optimum at 5. The bulk of the uptake (93%) was via carrier-mediated active transport. All of the 19 L-amino acids tested at 10 millimolar concentration inhibited the mediated uptake of 1 millimolar proline, the inhibitions varying from 18 to 76%. By studying how large a fraction of the mediated uptake was inhibitable by asparagine, alanine, glutamine, and leucine, the mediated uptake was shown to be due to three components. Two of these are most probably attributable to the two nonspecific uptake systems proposed earlier to act in the uptake of glutamine and leucine. The third component was not inhibited by glutamine, asparagine, or alanine, but was inhibited by unlabeled proline and leucine. The uptake by this system was apparently carrier-mediated active transport. D-Proline inhibited this system as strongly as L-proline. Nine of the 16 L-amino tested at 50 millimolar concentrations did not inhibit the uptake of 1 millimolar proline by this system. Valine, leucine, isoleucine, and the basic amino acids were inhibitory, but in spite of this, they did not appear to be taken up by this system. It seems therefore that in addition to two nonspecific amino acid uptake systems the scutella have an uptake system which is specific for proline. It is likely that this proline-specific system accounts for the bulk of proline uptake in a germinating grain.

  16. Increased skeletal:renal uptake ratio. [Bone-seekers

    SciTech Connect

    Cheng, T.H.; Holman, B.L.

    1980-08-01

    Twenty-four patients with increased skeletal:renal uptake ratios of /sup 99m/Tc-methylene diphosphonate were studied. Increased uptake was central in metastatic prostate carcinoma, peripheral in hematologic disorders, and heterogeneous in Paget disease and fibrous dysplasia. There was no discernible redistribution of skeletal uptake in patients with renal failure. Absence of both renal and bladder activity was not observed in patients with normal renal function. An increased ratio was always abnormal and frequently indicated diffuse bone disease.

  17. Methane uptake in forest soils along an urban-to-rural gradient in Pearl River Delta, South China.

    PubMed

    Zhang, Wei; Wang, Keya; Luo, Yiqi; Fang, Yunting; Yan, Junhua; Zhang, Tao; Zhu, Xiaomin; Chen, Hao; Wang, Wantong; Mo, Jiangming

    2014-01-01

    We investigated soil CH4 fluxes from six forests along an urban-to-rural gradient in Guangzhou City metropolitan area, South China. The most significant CH4 consumption was found in the rural site, followed by suburban, and then urban forest sites. The rates of CH4 uptake were significantly higher (by 38% and 44%, respectively for mixed forest and broadleaf forest) in the rural than in the urban forest site. The results indicate that soil water filled pore space (WFPS) is the primary factor for controlling CH4 consumption in subtropical forests. The reductions of soil CH4 uptake in urban forests were also influenced by the higher rates of atmospheric nitrogen (N) deposition and increases in soil nitrate (NO3(-)) and aluminum (Al(3+)) contents as a result of urbanization. Results from this work suggest that environmental changes associated with urbanization could decrease soil CH4 consumption in subtropical forests and potentially contribute to increase of atmospheric CH4 concentration.

  18. Uptake of environmental contaminants by small mammals in pickleweed habitats at San Francisco Bay, California

    USGS Publications Warehouse

    Clark, D.R.; Foerster, K.S.; Marn, C.M.; Hothem, R.L.

    1992-01-01

    Small mammals were livetrapped in pickleweed (Salicornia virginica) habitats near San Francisco Bay, California in order to measure the uptake of several contaminants and to evaluate the potential effects of these contaminants on the endangered salt marsh harvest mouse (Reithrodontomys raviventris). Tissues of house mice (Mus musculus), deer mice (Peromyscus maniculatus), and California voles (Microtus californicus) from nine sites were analyzed for chemical contaminants including mercury, selenium, cadmium, lead, and polychlorinated biphenyls (PCBs). Concentrations of contaminants differed significantly among sites and species. Mean concentrations at sites where uptake was greatest were less than maximum means for the same or similar species recorded elsewhere. Harvest mice (Reithrodontomys spp.) were captured only at sites where concentrations of mercury or PCBs were below specific levels in house mice. Additional studies aimed at the protection of the salt marsh harvest mouse are suggested. These include contaminant feeding studies in the laboratory as well as field monitoring of surrogate species and community structure in salt marsh harvest mouse habitats.

  19. Uptake of environmental contaminants by small mammals in pickleweed habitats at San Francisco Bay, California.

    PubMed

    Clark, D R; Foerster, K S; Marn, C M; Hothem, R L

    1992-05-01

    Small mammals were live-trapped in pickleweed (Salicornia virginica) habitats near San Francisco Bay, California in order to measure the uptake of several contaminants and to evaluate the potential effects of these contaminants on the endangered salt marsh harvest mouse (Reithrodontomys raviventris). Tissues of house mice (Mus musculus), deer mice (Peromyscus maniculatus), and California voles (Microtus californicus) from nine sites were analyzed for chemical contaminants including mercury, selenium, cadmium, lead, and polychlorinated biphenyls (PCBs). Concentrations of contaminants differed significantly among sites and species. Mean concentrations at sites where uptake was greatest were less than maximum means for the same or similar species recorded elsewhere. Harvest mice (Reithrodontomys spp.) were captured only at sites where concentrations of mercury or PCBs were below specific levels in house mice. Additional studies aimed at the protection of the salt marsh harvest mouse are suggested. These include contaminant feeding studies in the laboratory as well as field monitoring of surrogate species and community structure in salt marsh harvest mouse habitats. PMID:1586203

  20. Rhizosphere biophysics and root water uptake

    NASA Astrophysics Data System (ADS)

    Carminati, Andrea; Zarebanadkouki, Mohsen; Ahmed, Mutez A.; Passioura, John

    2016-04-01

    The flow of water into the roots and the (putative) presence of a large resistance at the root-soil interface have attracted the attention of plant and soil scientists for decades. Such resistance has been attributed to a partial contact between roots and soil, large gradients in soil matric potential around the roots, or accumulation of solutes at the root surface creating a negative osmotic potential. Our hypothesis is that roots are capable of altering the biophysical properties of the soil around the roots, the rhizosphere, facilitating root water uptake in dry soils. In particular, we expect that root hairs and mucilage optimally connect the roots to the soil maintaining the hydraulic continuity across the rhizosphere. Using a pressure chamber apparatus we measured the relation between transpiration rate and the water potential difference between soil and leaf xylem during drying cycles in barley mutants with and without root hairs. The samples were grown in well structured soils. At low soil moistures and high transpiration rates, large drops in water potential developed around the roots. These drops in water potential recovered very slowly, even after transpiration was severely decreased. The drops in water potential were much bigger in barley mutants without root hairs. These mutants failed to sustain high transpiration rates in dry conditions. To explain the nature of such drops in water potential across the rhizosphere we performed high resolution neutron tomography of the rhizosphere of the barleys with and without root hairs growing in the same soil described above. The tomograms suggested that the hydraulic contact between the soil structures was the highest resistance for the water flow in dry conditions. The tomograms also indicate that root hairs and mucilage improved the hydraulic contact between roots and soil structures. At high transpiration rates and low water contents, roots extracted water from the rhizosphere, while the bulk soil, due its

  1. Ligand modified nanoparticles increases cell uptake, alters endocytosis and elevates glioma distribution and internalization

    PubMed Central

    Gao, Huile; Yang, Zhi; Zhang, Shuang; Cao, Shijie; Shen, Shun; Pang, Zhiqing; Jiang, Xinguo

    2013-01-01

    Nanoparticles (NPs) were widely used in drugs/probes delivery for improved disease diagnosis and/or treatment. Targeted delivery to cancer cells is a highly attractive application of NPs. However, few studies have been performed on the targeting mechanisms of these ligand-modified delivery systems. Additional studies are needed to understand the transport of nanoparticles in the cancer site, the interactions between nanoparticles and cancer cells, the intracellular trafficking of nanoparticles within the cancer cells and the subcellular destiny and potential toxicity. Interleukin 13 (IL-13) peptide can specifically bind IL-13Rα2, a receptor that is highly expressed on glioma cells but is expressed at low levels on other normal cells. It was shown that the nanoparticels modification with the IL-13 peptide could improve glioma treatment by selectively increasing cellular uptake, facilitating cell internalization, altering the uptake pathway and increasing glioma localization. PMID:23982586

  2. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria

    PubMed Central

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv. PMID:26910324

  3. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria.

    PubMed

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv.

  4. Readily available phosphorous and nitrogen counteract for arsenic uptake and distribution in wheat (Triticum aestivum L.).

    PubMed

    Brackhage, Carsten; Huang, Jen-How; Schaller, Jörg; Elzinga, Evert J; Dudel, E Gert

    2014-01-01

    Elevated arsenic content in food crops pose a serious human health risk. Apart from rice wheat being another main food crop is possibly cultivated on contaminated sites. But for wheat uptake mechanisms are not entirely understood especially with regard to nutrient fertilization and different moisture regimes taking into account heavy rainfall events due to climate change. Here we show that especially higher P-fertilization under changing redox conditions may enhance arsenic uptake. This counteracts with higher N-fertilization reducing arsenic transfer and translocation into aboveground plant parts for both higher P-fertilization and reducing soil conditions. Arsenic speciation did not change in grain but for leaves P-fertilization together with reducing conditions increased the As(V) content compared to other arsenic species. Our results indicate important dependencies of nutrient fertilization, moisture conditions and substrate type on As accumulation of wheat as one of the most important crop plants worldwide with implications for agricultural practices. PMID:24821134

  5. Comparative uptake of uranium, thorium, and plutonium by biota inhabiting a contaminated Tennessee floodplain

    SciTech Connect

    Garten, C.T. Jr.; Bondietti, E.A.; Walker, R.L.

    1981-04-01

    The uptake of /sup 238/U, /sup 232/Th, and /sup 239/Pu from soil by fescue, grasshoppers, and small mammals was compared at the contaminated White Oak Creek floodplain in East Tennessee. Comparisons of actinide uptake were based on analyses of radionuclide ratios (U/Pu and Th/Pu) in soil and biota. U:Pu ratios in small mammal carcasses (shrews, mice, and rats) and bone samples from larger mammals (rabbit, woodchuck, opossum, and raccoon) were significantly greater (P less than or equal to 0.05) than U/Pu ratios in soil (based on 8M HNO/sub 3/ extractable). There was no significant difference between Th/Pu ratios in animals and soil. The order of actinide accumulation by biota from the site relative to contaminated soil was U > Th approx. = Pu.

  6. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria.

    PubMed

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv. PMID:26910324

  7. Readily available phosphorous and nitrogen counteract for arsenic uptake and distribution in wheat (Triticum aestivum L.)

    PubMed Central

    Brackhage, Carsten; Huang, Jen-How; Schaller, Jörg; Elzinga, Evert J.; Dudel, E. Gert

    2014-01-01

    Elevated arsenic content in food crops pose a serious human health risk. Apart from rice wheat being another main food crop is possibly cultivated on contaminated sites. But for wheat uptake mechanisms are not entirely understood especially with regard to nutrient fertilization and different moisture regimes taking into account heavy rainfall events due to climate change. Here we show that especially higher P-fertilization under changing redox conditions may enhance arsenic uptake. This counteracts with higher N-fertilization reducing arsenic transfer and translocation into aboveground plant parts for both higher P-fertilization and reducing soil conditions. Arsenic speciation did not change in grain but for leaves P-fertilization together with reducing conditions increased the As(V) content compared to other arsenic species. Our results indicate important dependencies of nutrient fertilization, moisture conditions and substrate type on As accumulation of wheat as one of the most important crop plants worldwide with implications for agricultural practices. PMID:24821134

  8. Readily available phosphorous and nitrogen counteract for arsenic uptake and distribution in wheat (Triticum aestivum L.)

    NASA Astrophysics Data System (ADS)

    Brackhage, Carsten; Huang, Jen-How; Schaller, Jörg; Elzinga, Evert J.; Dudel, E. Gert

    2014-05-01

    Elevated arsenic content in food crops pose a serious human health risk. Apart from rice wheat being another main food crop is possibly cultivated on contaminated sites. But for wheat uptake mechanisms are not entirely understood especially with regard to nutrient fertilization and different moisture regimes taking into account heavy rainfall events due to climate change. Here we show that especially higher P-fertilization under changing redox conditions may enhance arsenic uptake. This counteracts with higher N-fertilization reducing arsenic transfer and translocation into aboveground plant parts for both higher P-fertilization and reducing soil conditions. Arsenic speciation did not change in grain but for leaves P-fertilization together with reducing conditions increased the As(V) content compared to other arsenic species. Our results indicate important dependencies of nutrient fertilization, moisture conditions and substrate type on As accumulation of wheat as one of the most important crop plants worldwide with implications for agricultural practices.

  9. Predictive relationships for uptake of organic contaminants by hybrid poplar trees

    SciTech Connect

    Burken, J.G.; Schnoor, J.L.

    1998-11-01

    Twelve organic compounds commonly found at hazardous waste sites were studied for uptake by hybrid poplar trees. The vegetative uptake of many of these compounds has not previously been demonstrated for plant species being utilized for phytoremediation, such as hybrid poplar trees. Experiments were conducted hydroponically utilizing {sup 14}C-labeled compounds to ascertain translocation and fate. Predictive relationships for the translocation and partitioning to plant tissues were developed from the experimental data. Translocation and partitioning relationships based on compounds` octanol-water partitioning coefficients produced the best results, but the relationships did not allow for fully accurate prediction of each contaminant`s fate. Translocation and subsequent transpiration of volatile organic compounds (VOCs) from the leaves to the atmosphere was shown to be a significant pathway. As full-scale phytoremediation systems are deliberated, the pathways investigated here should be considered in terms of a contaminant removal mechanism and potential contamination of the vegetation.

  10. Contraction stimulates muscle glucose uptake independent of atypical PKC.

    PubMed

    Yu, Haiyan; Fujii, Nobuharu L; Toyoda, Taro; An, Ding; Farese, Robert V; Leitges, Michael; Hirshman, Michael F; Mul, Joram D; Goodyear, Laurie J

    2015-11-01

    Exercise increases skeletal muscle glucose uptake, but the underlying mechanisms are only partially understood. The atypical protein kinase C (PKC) isoforms λ and ζ (PKC-λ/ζ) have been shown to be necessary for insulin-, AICAR-, and metformin-stimulated glucose uptake in skeletal muscle, but not for treadmill exercise-stimulated muscle glucose uptake. To investigate if PKC-λ/ζ activity is required for contraction-stimulated muscle glucose uptake, we used mice with tibialis anterior muscle-specific overexpression of an empty vector (WT), wild-type PKC-ζ (PKC-ζ(WT)), or an enzymatically inactive T410A-PKC-ζ mutant (PKC-ζ(T410A)). We also studied skeletal muscle-specific PKC-λ knockout (MλKO) mice. Basal glucose uptake was similar between WT, PKC-ζ(WT), and PKC-ζ(T410A) tibialis anterior muscles. In contrast, in situ contraction-stimulated glucose uptake was increased in PKC-ζ(T410A) tibialis anterior muscles compared to WT or PKC-ζ(WT) tibialis anterior muscles. Furthermore, in vitro contraction-stimulated glucose uptake was greater in soleus muscles of MλKO mice than WT controls. Thus, loss of PKC-λ/ζ activity increases contraction-stimulated muscle glucose uptake. These data clearly demonstrate that PKC-λζ activity is not necessary for contraction-stimulated glucose uptake.

  11. Root Uptake of Pharmaceuticals and Personal Care Product Ingredients.

    PubMed

    Miller, Elizabeth L; Nason, Sara L; Karthikeyan, K G; Pedersen, Joel A

    2016-01-19

    Crops irrigated with reclaimed wastewater or grown in biosolids-amended soils may take up pharmaceuticals and personal care product ingredients (PPCPs) through their roots. The uptake pathways followed by PPCPs and the propensity for these compounds to bioaccumulate in food crops are still not well understood. In this critical review, we discuss processes expected to influence root uptake of PPCPs, evaluate current literature on uptake of PPCPs, assess models for predicting plant uptake of these compounds, and provide recommendations for future research, highlighting processes warranting study that hold promise for improving mechanistic understanding of plant uptake of PPCPs. We find that many processes that are expected to influence PPCP uptake and accumulation have received little study, particularly rhizosphere interactions, in planta transformations, and physicochemical properties beyond lipophilicity (as measured by Kow). Data gaps and discrepancies in methodology and reporting have so far hindered development of models that accurately predict plant uptake of PPCPs. Topics warranting investigation in future research include the influence of rhizosphere processes on uptake, determining mechanisms of uptake and accumulation, in planta transformations, the effects of PPCPs on plants, and the development of predictive models. PMID:26619126

  12. Uptake pathways of anionic and cationic photosensitizers into bacteria

    PubMed Central

    George, Saji; Hamblin, Michael R.; Kishen, Anil

    2009-01-01

    The effect of divalent cations (calcium and magnesium) and a permeabilizing agent (EDTA) on the uptake of a cationic photosensitizer (PS), methylene blue (MB), and two anionic PSs, rose bengal (RB) and indocyanine green (ICG), by Gram-positive Enterococcus faecalis and Gram-negative Actinobacillus actinomycetemcomitans was examined. The possible roles of multidrug efflux pumps and protein transporters in photosensitizer uptake were assessed in E. faecalis cells by studies using an efflux pump inhibitor (verapamil) and trypsin treatment respectively. Divalent cations enhanced the uptake and photodynamic inactivation potential of both RB and ICG in E. faecalis and A. actinomycetemcomitans, while they decreased the uptake and bacterial killing by MB. Verapamil increased the uptake of RB (possibly due to efflux pump inhibition), whereas trypsin treatment resulted in significant decrease in RB and ICG uptake. The results suggested that the uptake of anionic PSs by bacterial cells may be mediated through a combination of electrostatic charge interaction and by protein transporters, while the uptake of cationic PSs, as previously reported, is mediated by electrostatic interactions and self promoted uptake pathways. PMID:19492106

  13. Impact of ocean phytoplankton diversity on phosphate uptake

    PubMed Central

    Lomas, Michael W.; Bonachela, Juan A.; Levin, Simon A.; Martiny, Adam C.

    2014-01-01

    We have a limited understanding of the consequences of variations in microbial biodiversity on ocean ecosystem functioning and global biogeochemical cycles. A core process is macronutrient uptake by microorganisms, as the uptake of nutrients controls ocean CO2 fixation rates in many regions. Here, we ask whether variations in ocean phytoplankton biodiversity lead to novel functional relationships between environmental variability and phosphate (Pi) uptake. We analyzed Pi uptake capabilities and cellular allocations among phytoplankton groups and the whole community throughout the extremely Pi-depleted western North Atlantic Ocean. Pi uptake capabilities of individual populations were well described by a classic uptake function but displayed adaptive differences in uptake capabilities that depend on cell size and nutrient availability. Using an eco-evolutionary model as well as observations of in situ uptake across the region, we confirmed that differences among populations lead to previously uncharacterized relationships between ambient Pi concentrations and uptake. Supported by novel theory, this work provides a robust empirical basis for describing and understanding assimilation of limiting nutrients in the oceans. Thus, it demonstrates that microbial biodiversity, beyond cell size, is important for understanding the global cycling of nutrients. PMID:25422472

  14. Specific in vitro uptake of serotonin by cells in the anterior pituitary of the rat

    SciTech Connect

    Johns, M.A.; Azmitia, E.C.; Krieger, D.T.

    1982-03-01

    In vivo studies have suggested that serotonin (5HT) influences anterior pituitary function at the hypothalamic level. The present in vitro study investigated the possibility that 5HT may act directly on the anterior pituitary. The high affinity uptake of (3H)5HT into adult rat anterior pituitary tissue was examined in two types of experiments. 1) To test the specificity and saturability of uptake of 5HT in the anterior pituitary, pituitary tissue was incubated (37 C) with (3H)5HT (10(-8)-10(-6) M) in the presence and absence of excess (10(-5) M) unlabeled 5HT, norepinephrine, fluoxetine (FLUOX), metergoline, or cyproheptadine. A Hofstee analysis of the specific uptake of (3H)5HT gave an apparent Km value of 4.23 x 10(-7) M and a Vmax of 1576 pmol/g/10 min (3H)5HT. The total uptake of (3H)5HT was not altered by norepinephrine or metergoline, but was significantly reduced (P less than 0.01-0.001) by FLUOX and cyproheptadine. Uptake was shown to be temperature and sodium dependent and not directly dependent on energy derived from glycolysis or aerobic metabolism. 2) To study the site of uptake of 5 HT in the anterior pituitary, in concomitant radioautographic experiments, tissue was incubated with (3H)5HT with and without excess 5HT or FLUOX. Three patterns of silver grain distribution were observed: 1) nonrandom concentrations over select anterior pituitary cells near blood vessels, 2) heavy aggregates of silver grains usually associated with blood vessels, and 3) a seemingly random dispersal of grains over pituitary tissue. Tissue incubated with (3H)5HT alone contained 10% heavily labeled cells, 32% moderately labeled cells, and 58% weakly labeled cells. In contrast, no heavily labeled cells were seen when tissue was incubated with either excess 5HT or FLUOX in addition to (3H)5HT. Our findings of saturable and specific high affinity uptake of (3H)5HT into a subgroup of anterior pituitary cells suggest a direct pituitary action of 5HT.

  15. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  16. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

    NASA Astrophysics Data System (ADS)

    Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

    2012-07-01

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  17. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  18. ORCID Uptake in the Astronomical Community

    NASA Astrophysics Data System (ADS)

    Holmquist, Jane

    2015-08-01

    The IAU General Assembly provides librarians with a unique opportunity to interact with astronomers from all over the world. From the perspective of an ORCID Ambassador, the Focus Group Meeting on "Scholarly Publication in Astronomy" also provides an opportunity to demonstrate the cooperation and collaboration needed by individual astronomers, societies, librarians, publishers and bibliographic database providers to achieve universal adoption of ORCID, a standard unique identifier for authors, just as the DOI (digital object identifier) has been adopted for each journal article published.I propose to 1) present at the Focus Group Meeting an update on the uptake of ORCID by members of the astronomical community and 2) set up a small station (TBA) near the IAU registration area where librarians can show researchers how to register for an ORCID in 30 seconds.

  19. Plant uptake of sludge-borne PCBs

    SciTech Connect

    O'Connor, G.A.; Kiehl, D.; Eiceman, G.A.; Ryan, J.A.

    1990-01-01

    Plant uptake of sludge-borne polychlorinated biphenyls (PCBs) (similar to Aroclor 1248) was evaluated in a greenhouse study with two food-chain crops and a grass species. Polychlorinated biphenyl loading to two soils was varied in one experiment by adding different rates of a municipal sewage sludge heavily contaminated (52 mg/kg) with PCBs. In a second experiment, Aroclor 1248 was spiked into unamended soils or soils amended with another sludge containing <1mg/kg PCBs. Analysis of PCBs was by GC/MS with a reliable detection limit in plants of 20 microg/kg for individual chlorinated classes (tri, tetra-, and pentachlorobiphenyls) and total PCBs. Only carrots (Daucus carota) were contaminated with PCBs, and contamination was restricted to carrot peels. Current USEPA guidelines for land application of sludges based on sludge PCB content are shown to be extremely conservative.

  20. Female condom uptake and acceptability in Zimbabwe.

    PubMed

    Napierala, Sue; Kang, Mi-Suk; Chipato, Tsungai; Padian, Nancy; van der Straten, Ariane

    2008-04-01

    As the first phase of a two-phase prospective cohort study to assess the acceptability of the diaphragm as a potential HIV/STI prevention method, we conducted a 2-month prospective study and examined the effect of a male and female condom intervention on female condom (FC) use among 379 sexually active women in Harare, Zimbabwe. Reported use of FC increased from 1.1% at baseline to 70.6% at 2-month follow-up. Predictors of FC uptake immediately following the intervention included interest in using FC, liking FC better than male condoms, and believing one could use them more consistently than male condoms. Women reported 28.8% of sex acts protected by FC in the 2 weeks prior to last study visit. Though FC may not be the preferred method for the majority of women, with access, proper education, and promotion they may be a valuable option for some Zimbabwean women. PMID:18433318

  1. Factors affecting stomatal uptake of ozone by different canopies and a comparison between dose and exposure.

    PubMed

    Zhang, Leiming; Vet, Robert; Brook, Jeffrey R; Legge, Allan H

    2006-10-15

    Measured ozone (O(3)) and carbon dioxide (CO(2)) concentrations and fluxes over five different canopies (mixed coniferous-deciduous forest, deciduous forest, corn, soybean and pasture) in the eastern USA were analyzed to investigate the stomatal uptake of O(3). It was found that the ambient O(3) concentration levels had little effect on stomatal conductance. However, the accumulated stomatal uptake of O(3), upon reaching a threshold value on any given day, appears to reduce the rate of further O(3) uptake substantially. This may explain why the maximum O(3) deposition velocity often appeared in the early morning hours over some forest canopies. Substantially reduced CO(2) fluxes over wet canopies compared to dry canopies suggest that stomata were likely partially or totally blocked by water droplets or films when canopies were wet. By using a big-leaf dry deposition model, measured O(3) fluxes were separated into stomatal and non-stomatal portions. It was estimated that stomatal uptake contributed 55-75% of the total daytime O(3) fluxes and 40-60% of the total daytime plus nighttime fluxes, depending on canopy type. This suggests that about half of the total O(3) flux occurred through the non-stomatal pathway. At three locations (deciduous forest, corn and soybean sites), O(3) concentrations of 30-60 ppb and of 60-85 ppb contributed equally to the accumulated stomatal fluxes, while at the other two locations (mixed coniferous-deciduous forest and pasture sites), concentrations of 30-60 ppb contributed twice as much as those from 60 to 85 ppb.

  2. Ouabain uptake by endocytosis in isolated guinea pig atria

    SciTech Connect

    Nunez-Duran, H.; Riboni, L.; Ubaldo, E.; Kabela, E.; Barcenas-Ruiz, L. Instituto Nacional de Cardiologia, Mexico DF )

    1988-10-01

    Mammalian cells specifically internalize some molecular species through receptor-mediated endocytosis (RME). The authors have used four different experimental protocols to investigate whether ouabain enters cardiac cells of guinea pig atrium through this pathway. First, by electron microscope morphometry the authors found that ouabain increased endocytic vesicles in atrial cells. Second, by scintillation counting they found that ({sup 3}H)ouabain uptake by the tissue is decreased by three treatments that decrease RME, i.e., NH{sub 4}Cl, trifluoperazine, and 16 mM (K{sup +}){sub 0}. Third, by radioautography at the electron microscope level, they checked that in preceding experiments ({sup 3}H)ouabain was washed out of plasma membrane after 60-min rinse and interiorized into the cardiac cells. Fourth, isometric tension recordings showed that the positive inotropic effect of ouabain was diminished in the presence of inhibitors, whereas that of a hydrophobic analogue, ouabagenin, was not affected. These results suggest that ouabain enters cardiac cells through RME and also that an intracellular site may, at least in part, be responsible for its inotropic effect.

  3. Copper uptake by Eichhornia crassipes exposed at high level concentrations.

    PubMed

    Melignani, Eliana; de Cabo, Laura Isabel; Faggi, Ana María

    2015-06-01

    The objective of this study was to assess the growth of water hyacinth (Eichhornia crassipes) and its ability to accumulate Cu from polluted water with high Cu concentrations and a mixture of other contaminants under short-term exposure, in order to use this species for the remediation of highly contaminated sites. Two hydroponic experiments were performed under greenhouse conditions for 7 days. One of them consisted of growing water hyacinth in Hoagland solution supplemented with 15 or 25 mg Cu/L and a control. The other one contained water hyacinth growing in polluted river water supplemented with 15 mg Cu/L and a control. Cu was accumulated principally in roots. The maximum Cu concentration was 23,387.2 mg/kg dw in the treatment of 25 mg Cu/L in Hoagland solution. Cu translocation from roots to leaves was low. The mixture of 15 mg Cu/L with polluted water did not appear to have toxic effects on the water hyacinth. This plant showed a remarkable uptake capacity under elevated Cu concentrations in a mixture of pollutants similar to pure industrial effluents in a short time of exposure. This result has not been reported before, to our knowledge. This species is suitable for phytoremediation of waters subject to discharge of mixed industrial effluents containing elevated Cu concentrations (≥15 mg Cu/L), as well as nutrient-rich domestic wastewaters.

  4. Methane uptake in agricultural and old-field ecosystems

    SciTech Connect

    Reed, W.L.; Halstead, S.J.; Robertson, G.P. Michigan State Univ., East Lansing )

    1993-06-01

    Atmospheric methane (CH[sub 4]) concentrations are rising approximately 1% per year, with important consequences for the earth's radiation balance and tropospheric chemistry. Sources of this increase are not well known; recent evidence suggests that land conversion to agriculture may play some role in this increase if CH[sub 4] consumption in upland soils is suppressed by agronomic activities. We tested this hypothesis in a series of replicated agricultural and old-field communities at the KBS LTER site in southwest Michigan. We measured CH[sub 4] flux with static chambers in 6 different cropping systems (conventional till and no-till annual crops, ridge-till organic based crops, perennial crops) and in early successional and mid-succession (never tilled) old field communities. Chambers were sampled 17 times over the 1992 growing season and analyzed for CH[sub 4], N[sub 2]O, and CO[sub 2]. We found significant but highly variable CH[sub 4] uptake on some dates in all 8 ecosystem types, with most consistent consumption in the organic based crops and old-field communities.

  5. Uptake, Distribution, and Speciation of Chromium in Brassica Juncea

    SciTech Connect

    Bluskov, S.; Arocena, J.M.; Omotoso, O.O.; Young, J.P.

    2008-06-09

    Brassica juncea (Indian mustard) has been widely used in phytoremediation because of its capacity to accumulate high levels of chromium (Cr) and other metals. The present study was conducted to investigate mechanism(s) involved in Cr binding and sequestration by B. juncea. The plants were grown under greenhouse conditions in field-moist or air-dried soils, amended with 100 mg kg{sup -1} of Cr (III or VI). The plant concentrated Cr mainly in the roots. B. juncea removed an average of 48 and 58 {micro}g Cr per plant from Cr (III) and Cr (VI)-treated soils, respectively. The uptake of Cr was not affected by the moisture status of the soils. X-ray absorption near-edge spectroscopy measurements showed only Cr (III) bound predominantly to formate and acetate ligands, in the bulk and rhizosphere soils, respectively. In the plant tissues, Cr (III) was detected, primarily as acetate in the roots and oxalate in the leaves. X-ray microprobe showed the sites of Cr localization, and probably sequestration, in epidermal and cortical cells in the roots and epidermal and spongy mesophyll cells in the leaves. These findings demonstrate the ability of B. juncea to detoxify more toxic Cr (VI), thereby making this plant a potential candidate for phytostabilization.

  6. Measurement of uptake and release of tritium by tungsten

    SciTech Connect

    Nakayama, M.; Torikai, Y.; Saito, M.; Penzhorn, R.D.; Isobe, K.; Yamanishi, T.; Kurishita, H.

    2015-03-15

    Tungsten is currently contemplated as plasma facing material for the divertor of future fusion machines. In this paper the uptake of tritium by tungsten and its release behavior have been investigated. Tungsten samples have been annealed at various temperatures and loaded at also different temperatures with deuterium containing 7.2 % tritium at a pressure of 1.2 kPa. A specific system was designed to assess the release of tritiated water and molecular tritium by the samples. Due to the rather low solubility of hydrogen isotopes in tungsten it is particularly important to be aware of the presence of hydrogen traps or thin oxide films. As shown in this work, traps or oxide films may affect the retention capability of tungsten and lead to significantly modified release properties. It became clear that there were capture sites that had different thermal stability and different capture intensity in tungsten after polishing, or oxide films that were grown on the surface of tungsten and had barrier effects.

  7. Copper uptake by Eichhornia crassipes exposed at high level concentrations.

    PubMed

    Melignani, Eliana; de Cabo, Laura Isabel; Faggi, Ana María

    2015-06-01

    The objective of this study was to assess the growth of water hyacinth (Eichhornia crassipes) and its ability to accumulate Cu from polluted water with high Cu concentrations and a mixture of other contaminants under short-term exposure, in order to use this species for the remediation of highly contaminated sites. Two hydroponic experiments were performed under greenhouse conditions for 7 days. One of them consisted of growing water hyacinth in Hoagland solution supplemented with 15 or 25 mg Cu/L and a control. The other one contained water hyacinth growing in polluted river water supplemented with 15 mg Cu/L and a control. Cu was accumulated principally in roots. The maximum Cu concentration was 23,387.2 mg/kg dw in the treatment of 25 mg Cu/L in Hoagland solution. Cu translocation from roots to leaves was low. The mixture of 15 mg Cu/L with polluted water did not appear to have toxic effects on the water hyacinth. This plant showed a remarkable uptake capacity under elevated Cu concentrations in a mixture of pollutants similar to pure industrial effluents in a short time of exposure. This result has not been reported before, to our knowledge. This species is suitable for phytoremediation of waters subject to discharge of mixed industrial effluents containing elevated Cu concentrations (≥15 mg Cu/L), as well as nutrient-rich domestic wastewaters. PMID:25529492

  8. The phylogeny of uptake hydrogenases in Frankia.

    PubMed

    Leul, Melakeselam; Normand, Philippe; Sellstedt, Anita

    2009-03-01

    Uptake hydrogenase is an enzyme that is beneficial for nitrogen fixation in bacteria. Recent studies have shown that Frankia sp. has two sets of uptake hydrogenase genes, organized in synton 1 and synton 2. In the present study, phylogenetic analysis of the structural subunits of hydrogenase syntons 1 and 2 showed a distinct clustering pattern between the proteins of Frankia strains that were isolated from different host plants and non-Frankia organisms. The structural subunits of hydrogenase synton 1 of Frankia sp. CpI1, Frankia alni ACN14a, and F. alni AvCI1 were grouped together while those of Frankia spp. CcI3, KB5, UGL140104, and UGL011102 formed another group. The structural subunits of hydrogenase synton 2 of F. alni ACN14a and Frankia spp. CcI3 and BCU110501 grouped together, but those of Frankia spp. KB5 and CpI1, F. alni ArI3, and F. alniAvCI1 comprised a separate group. The structural subunits of hydrogenase syntons 1 and 2 of Frankia sp. EAN1pec were more closely related to those of non-Frankia bacteria, i.e., Streptomyces avermitilis and Anaeromyxobacter sp., respectively, than to those of other Frankia strains, suggesting the occurrence of lateral gene transfer between these organisms. In addition, the accessory Hyp proteins of hydrogenase syntons 1 and 2 of F. alni ACN14a and Frankia sp. CcI3 were shown to be phylogenetically more related to each other than to those of Frankia EAN1pec. PMID:19440980

  9. Uptake of Nitroaromatic Compounds by Polymeric Tubing

    SciTech Connect

    BOUNKEUA, VIENGNGEUN; RODACY, PHILIP J.

    2001-04-01

    The type of polymeric material used in the manufacturing of tubing determines its strength, elasticity, and durability. Tubing made of polymeric material is commonly used for analytical work because it is readily available, inexpensive and can be relatively inert. Polymeric tubing is used in many sampling applications for explosive compounds. A major concern is the uptake of the explosive compounds into or onto the tubing during sampling. Because of the reactive nature of explosives, it is important that as little of the detectable explosive as possible is lost by tubing uptake. It is also important that nothing leaches out of the tubing to interfere with the detection of explosives. High Performance Liquid Chromatography (HPLC) is commonly used for the analysis of trace levels of explosive compounds in the range of parts per billion (ppb) to parts per million (ppm). This study attempts to determine which types of polymers are most conducive to sampling applications where large volumes of dilute explosive solutions are collected through a length of tubing for analysis. This was determined by analyzing the amount of explosive lost from solution per cm{sup 2} of tubing in solution. It was determined that tubing made of polyethylene, teflon, polypropylene, or KYNAR{reg_sign} is recommended for dilute trinitrotoluene (TNT) solution analyses. Tubing made of polypropylene, PHARMED{reg_sign}, KYNAR{reg_sign}, or polyethylene is recommended for analyses involving dilute explosive solutions of RDX. Tubing made from polyurethane, TYGON{reg_sign}, nylon, vinyl, gum rubber, or reinforced PVC are not recommended because they leach contaminants into solution that may interfere with HPLC analysis of explosive peaks.

  10. Fatty acid uptake in normal human myocardium

    SciTech Connect

    Vyska, K.; Meyer, W.; Stremmel, W.; Notohamiprodjo, G.; Minami, K.; Machulla, H.J.; Gleichmann, U.; Meyer, H.; Koerfer, R. )

    1991-09-01

    Fatty acid binding protein has been found in rat aortic endothelial cell membrane. It has been identified to be a 40-kDa protein that corresponds to a 40-kDa fatty acid binding protein with high affinity for a variety of long chain fatty acids isolated from rat heart myocytes. It is proposed that this endothelial membrane fatty acid binding protein might mediate the myocardial uptake of fatty acids. For evaluation of this hypothesis in vivo, influx kinetics of tracer-labeled fatty acids was examined in 15 normal subjects by scintigraphic techniques. Variation of the plasma fatty acid concentration and plasma perfusion rate has been achieved by modulation of nutrition state and exercise conditions. The clinical results suggest that the myocardial fatty acid influx rate is saturable by increasing fatty acid plasma concentration as well as by increasing plasma flow. For analysis of these data, functional relations describing fatty acid transport from plasma into myocardial tissue in the presence and absence of an unstirred layer were developed. The fitting of these relations to experimental data indicate that the free fatty acid influx into myocardial tissue reveals the criteria of a reaction on a capillary surface in the vicinity of flowing plasma but not of a reaction in extravascular space or in an unstirred layer and that the fatty acid influx into normal myocardium is a saturable process that is characterized by the quantity corresponding to the Michaelis-Menten constant, Km, and the maximal velocity, Vmax, 0.24 {plus minus} 0.024 mumol/g and 0.37 {plus minus} 0.013 mumol/g(g.min), respectively. These data are compatible with a nondiffusional uptake process mediated by the initial interaction of fatty acids with the 40-kDa membrane fatty acid binding protein of cardiac endothelial cells.

  11. Effect of THIP and SL 76002, two clinically experimented GABA-mimetic compounds, on anterior pituitary GABA receptors and prolactin secretion in the rat

    SciTech Connect

    Apud, J.A.; Masotto, C.; Racagni, G.

    1987-03-02

    In the present study, the ability of three direct GABA agonists, muscimol, THIP and SL 76002 to displace /sup 3/H-GABA binding from anterior pituitary and medio-basal hypothalamus membranes was evaluated. Further, the effect of both THIP and SL 76002 on baseline prolactin levels or after stimulation of hormone release with haloperidol has been also studied. Either muscimol, THIP or SL 76002 have shown to posses 7-, 7- and 3-fold higher affinity, respectively, for the central nervous system than for the anterior pituitary /sup 3/H-GABA binding sites. Moreover, THIP and SL 76002 have demonstrated to be respectively, 25- and 1000- fold less potent than muscimol in inhibiting /sup 3/H- GABA binding at the level of the anterior pituitary and about 25- and 2700-fold less potent at the level of the medio-basal hypothalamus. Under basal conditions, either THIP or SL 76002 were ineffective to reduce prolactin release. However, after stimulation of prolactin secretion through blockade of the dopaminergic neurotransmission with haloperidol (0.1 mg/kg), both THIP (10 mg/kg) and SL 76002 (200 mg/kg) significantly counteracted the neuroleptic-induced prolactin rise with a potency which is in line with their ability to inhibit /sup 3/H-GABA binding in the anterior pituitary. The present results indicate that both compounds inhibit prolactin release under specific experimental situations probably through a GABAergic mechanism. In view of the endocrine effects of these GABA-mimetic compounds, the possibility arises for an application of these type of drugs in clinical neuroendocrinology. 35 references, 3 figures, 2 tables.

  12. Nitrogen uptake by natural populations of phytoplankton and primary production in the Pacific Ocean: regional variability of uptake capacity

    SciTech Connect

    Kanda, J.; Saino, T.; Hattori, A.

    1985-09-01

    Uptake of nitrogenous nutrients (ammonium, nitrate, and urea) and inorganic carbon by natural populations of phytoplankton in surface waters of the Pacific Ocean was measured by a /sup 13/C-/sup 15/N dual tracer technique. Regional variability of uptake capacity and its correlation with environmental parameters were examined. The uptakes proceeded linearly with time for at least 3 h. Half-saturation constants for uptake of ammonium, nitrate, and urea were generally low (about 0.1 ..mu..g-atom N liter/sup -1/). The maximum uptake rate of nitrate was well correlated with the uptake of inorganic carbon; these two rates expressed on a chlorophyll a basis were relatively lower at higher latitude stations. Maximum uptake rates of ammonium and urea clearly covaried with the ambient water temperature. The estimated turnover times of ammonium at subtropical and tropical stations ranged from 1 to 3 days. The contribution of uptake in the dark was larger at low latitude stations. Regional variation of uptake capacity is correlated with temperature and possibly light, but not with nutrient supply.

  13. An approach to monitoring influenza vaccination uptake across Europe.

    PubMed

    Kroneman, M; Paget, W J; Meuwissen, L E; Joseph, C; Kennedy, H

    2008-05-15

    Currently, the monitoring of influenza vaccination uptake is mainly a national issue. As influenza infection easily crosses international borders, it is in the interest of all countries to have a high vaccine uptake in people who may be vulnerable when influenza spreads. A Europe-wide monitoring system can provide insight into the strengths and weaknesses of uptake rates in countries and, on ce sufficient levels are achieved, can safeguard the continuation of the achieved levels. This paper aims to address the following issues: a) How is influenza vaccination uptake monitored in Europe? b) What methods to monitor vaccination uptake are available and what are their limitations? c) What steps should be taken to implement a European-wide influenza vaccination uptake monitoring system? Based on existing literature and experiences in monitoring influenza vaccination uptake, an approach to set up a European-wide monitoring system is proposed. The following issues were identified as relevant for influenza vaccination uptake monitoring: a) Agreement on the population groups in which vaccination uptake should be monitored; b) The frequency of data collection; c) The importance of sharing experiences regarding existing influenza vaccination campaigns in order to learn from each other, and develop 'best practices'; d) The need to publish uptake data in close relation with influenza surveillance data and other European efforts on dissemination of vaccination knowledge. To stimulate the discussion on implementing a pan-European influenza uptake monitoring scheme the following recommendations were suggested : a) Develop a common set of variables; b) Build on experience from individual countries; c) Create a coordinating body; d) Create or identify a platform to publish the data; e) Start small and expand rapidly. PMID:18761972

  14. Natural Competence and the Evolution of DNA Uptake Specificity

    PubMed Central

    Mell, Joshua Chang

    2014-01-01

    Many bacteria are naturally competent, able to actively transport environmental DNA fragments across their cell envelope and into their cytoplasm. Because incoming DNA fragments can recombine with and replace homologous segments of the chromosome, competence provides cells with a potent mechanism of horizontal gene transfer as well as access to the nutrients in extracellular DNA. This review starts with an introductory overview of competence and continues with a detailed consideration of the DNA uptake specificity of competent proteobacteria in the Pasteurellaceae and Neisseriaceae. Species in these distantly related families exhibit strong preferences for genomic DNA from close relatives, a self-specificity arising from the combined effects of biases in the uptake machinery and genomic overrepresentation of the sequences this machinery prefers. Other competent species tested lack obvious uptake bias or uptake sequences, suggesting that strong convergent evolutionary forces have acted on these two families. Recent results show that uptake sequences have multiple “dialects,” with clades within each family preferring distinct sequence variants and having corresponding variants enriched in their genomes. Although the genomic consensus uptake sequences are 12 and 29 to 34 bp, uptake assays have found that only central cores of 3 to 4 bp, conserved across dialects, are crucial for uptake. The other bases, which differ between dialects, make weaker individual contributions but have important cooperative interactions. Together, these results make predictions about the mechanism of DNA uptake across the outer membrane, supporting a model for the evolutionary accumulation and stability of uptake sequences and suggesting that uptake biases may be more widespread than currently thought. PMID:24488316

  15. Relationship between Nitrite Reduction and Active Phosphate Uptake in the Phosphate-Accumulating Denitrifier Pseudomonas sp. Strain JR 12

    PubMed Central

    Barak, Yoram; van Rijn, Jaap

    2000-01-01

    Phosphate uptake by the phosphate-accumulating denitrifier Pseudomonas sp. JR12 was examined with different combinations of electron and carbon donors and electron acceptors. Phosphate uptake in acetate-supplemented cells took place with either oxygen or nitrate but did not take place when nitrite served as the final electron acceptor. Furthermore, nitrite reduction rates by this denitrifier were shown to be significantly reduced in the presence of phosphate. Phosphate uptake assays in the presence of the H+-ATPase inhibitor N,N′-dicyclohexylcarbodiimide (DCCD), in the presence of the uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP), or with osmotic shock-treated cells indicated that phosphate transport over the cytoplasmic membrane of this bacterium was mediated by primary and secondary transport systems. By examining the redox transitions of whole cells at 553 nm we found that phosphate addition caused a significant oxidation of a c-type cytochrome. Based on these findings, we propose that this c-type cytochrome serves as an intermediate in the electron transfer to both nitrite reductase and the site responsible for active phosphate transport. In previous studies with this bacterium we found that the oxidation state of this c-type cytochrome was significantly higher in acetate-supplemented, nitrite-respiring cells (incapable of phosphate uptake) than in phosphate-accumulating cells incubated with different combinations of electron donors and acceptors. Based on the latter finding and results obtained in the present study it is suggested that phosphate uptake in this bacterium is subjected to a redox control of the active phosphate transport site. By means of this mechanism an explanation is provided for the observed absence of phosphate uptake in the presence of nitrite and inhibition of nitrite reduction by phosphate in this organism. The implications of these findings regarding denitrifying, phosphate removal wastewater plants is discussed. PMID

  16. Analysing global ecosystem CO2 uptake capacity with plant trait data

    NASA Astrophysics Data System (ADS)

    van de Weg, Martine; Sadat Musavi, Talie; van Bodegom, Peter; Kattge, Jens; Mahecha, Miguel; Reichstein, Markus; Bahn, Michael

    2014-05-01

    Given the modulating role of vegetation in the global carbon cycle, there is a demand for simple and general scaling relationships of vegetation characteristics and ecosystem CO2-uptake and emissions. On a leaf level, is it well established that plant trait foliar nitrogen (N) relates strongly with leaf level CO2. Furthermore, ecosystem productivity or CO2 uptake capacity have been related directly with whole-canopy N concentrations for a variety of ecosystems such as grasslands, and boreal, temporal and tropical forests. However, studies on the global validity of these leaf and ecosystem level relationships have been lacking up to date. The arrival of the large plant trait database TRY database offers the opportunity to link plant trait and ecosystem functioning on a global scale. In this study, we used CO2 flux data from the FLUXNET database, with plant trait (Narea) data from TRY and Narea measurements from a selection of FLUXNET sites as well. For 83 global FLUXNET sites, which had information available on species composition, we derived the light saturated gross primary productivity (GPP1000). We used MODIS LAI and fPAR, together with the species' relative height and abundance data, to up-scale the TRY derived Narea values to a canopy value per site (Ncanopy). For this calculation we assumed that top canopy leaves contribute more to CO2 uptake, and used a Lambert-Beer canopy light extinction principle to weigh the relative contribution per species to the final Ncanopy value. For our analyses, we divided the sites in five different vegetation classes: broad leaved forests, needle leaved forests, grasslands, crops and (sub)arctic non-forest vegetation. Site-measured Nareadata corroborated well with TRY derived Narea data, giving confidence in using a database such as TRY for global analyses like ours. Ncanopy alone explained 18 % of the observed variation in maximum (90th percentile) GPP1000 with a linear model. When adding the different vegetation types as a

  17. Inter- and intracellular relationship of substance P-containing neurons with serotonin and GABA in the dorsal raphe nucleus: combination of autoradiographic and immunocytochemical techniques

    SciTech Connect

    Magoul, R.; Onteniente, B.; Oblin, A.; Calas, A.

    1986-06-01

    Double-labeling experiments were performed at the electron microscopic level in the dorsal raphe nucleus of rat, in order to study the inter- and intracellular relationship of substance P with gamma-aminobutyric acid (GABA) and serotonin. Autoradiography for either (/sup 3/H)serotonin or (/sup 3/H)GABA was coupled, on the same tissue section, with peroxidase-antiperoxidase immunocytochemistry for substance P in colchicine-treated animals. Intercellular relationships were represented by synaptic contacts made by (/sup 3/H)serotonin-labeled terminals on substance P-containing somata and dendrites, and by substance P-containing terminals on (/sup 3/H)GABA-labeled cells. Intracellular relationships were suggested by the occurrence of the peptide within (/sup 3/H)serotonin-containing and (/sup 3/H)GABA-containing cell bodies and fibers. Doubly labeled varicosities of the two kinds were also observed in the supraependymal plexus adjacent to the dorsal raphe nucleus. The results demonstrated that, in addition to reciprocal synaptic interactions made by substance P with serotonin and GABA, the dorsal raphe nucleus is the site of intracellular relationships between the peptide and either the amine or the amino acid.

  18. Uptake and depuration of 131I by the edible periwinkle Littorina littorea: uptake from seawater.

    PubMed

    Vives i Batlle, J; Wilson, R C; McDonald, P; Parker, T G

    2005-01-01

    Uptake and depuration experiments for the edible periwinkle Littorina littorea have been performed using 131I-labelled seawater. Throughout the experimental phase the winkles were fed on unlabelled Chondrus crispus. 131I concentrations in winkles during uptake followed linear first-order kinetics with an uptake half-time of 11 days, whereas for depuration a triphasic sequence with biological half-lives of 4, 23 and 56 days was determined. In general, iodine turnover in winkles via labelled seawater appears to be slower than observed for other molluscs (2-3 days). Most of the activity prior to and after depuration is found to be in the shell, with indications that shell and soft parts accumulate and depurate 131I at a similar rate. The operculum displays the highest specific activity of all fractions with a concentration factor of 750 l kg(-1). Concentration factors for whole winkle, shell, soft parts and digestive gland are in the order of 40-60 l kg(-1), higher than the IAEA recommended CF value for iodine in molluscs of 10 l kg(-1). The 131I CF in winkles is closer to that of the conservative radionuclides 99Tc and 137Cs than the CF of the particle reactive radionuclides (239,240)Pu and 241Am. PMID:15465179

  19. Silver Uptake, Distribution, and Effect on Calcium, Phosphorus, and Sulfur Uptake 1

    PubMed Central

    Koontz, Harold V.; Berle, Karen L.

    1980-01-01

    Bean, corn, and tomato plants were grown in a nutrient solution labeled with 32P, 45Ca, or 35S and varying concentrations of AgNO3. Following a 6-hour treatment period, plants were harvested and analyzed. A low Ag+ concentration (50 nanomolar) inhibited the shoot uptake of the ions investigated. In the roots, Ca uptake increased whereas P and S uptake decreased. Autoradiograms of bean and corn plants, using 110mAg, showed that Ag+ was uniformly deposited in the bean shoot, but corn shoots had regions of high activity along the leaf margins and at the tips where guttation had occurred. Roots were heavily labeled and shoots (especially the new growth) continued to accumulate Ag+ even after the intact plant was returned to Ag-free solution. Silver was believed to be phloem-mobile since it was exported from a treated leaf. Bean plants removed one-half the Ag+ from 4 liters of nutrient solution containing 50 nanomolar AgNO3 within 1.5 hours, but took 16 hours for 20 liters of solution. Images PMID:16661185

  20. A local renal renin-angiotensin system activation via renal uptake of prorenin and angiotensinogen in diabetic rats.

    PubMed

    Tojo, Akihiro; Kinugasa, Satoshi; Fujita, Toshiro; Wilcox, Christopher S

    2016-01-01

    The mechanism of activation of local renal renin-angiotensin system (RAS) has not been clarified in diabetes mellitus (DM). We hypothesized that the local renal RAS will be activated via increased glomerular filtration and tubular uptake of prorenin and angiotensinogen in diabetic kidney with microalbuminuria. Streptozotocin (STZ)-induced DM and control rats were injected with human prorenin and subsequently with human angiotensinogen. Human prorenin uptake was increased in podocytes, proximal tubules, macula densa, and cortical collecting ducts of DM rats where prorenin receptor (PRR) was expressed. Co-immunoprecipitation of kidney homogenates in DM rats revealed binding of human prorenin to the PRR and to megalin. The renal uptake of human angiotensinogen was increased in DM rats at the same nephron sites as prorenin. Angiotensin-converting enzyme was increased in podocytes, but decreased in the proximal tubules in DM rats, which may have contributed to unchanged renal levels of angiotensin despite increased angiotensinogen. The systolic blood pressure increased more after the injection of 20 μg of angiotensinogen in DM rats than in controls, accompanied by an increased uptake of human angiotensinogen in the vascular endothelium. In conclusion, endocytic uptake of prorenin and angiotensinogen in the kidney and vasculature in DM rats was contributed to increased tissue RAS and their pressor response to angiotensinogen.

  1. Mesoscopic aspects of root water uptake modeling - Hydraulic resistances and root geometry interpretations in plant transpiration analysis

    NASA Astrophysics Data System (ADS)

    Vogel, Tomas; Votrubova, Jana; Dusek, Jaromir; Dohnal, Michal

    2016-02-01

    In the context of soil water flow modeling, root water uptake is often evaluated based on water potential difference between the soil and the plant (the water potential gradient approach). Root water uptake rate is modulated by hydraulic resistance of both the root itself, and the soil in the root vicinity. The soil hydraulic resistance is a function of actual soil water content and can be assessed assuming radial axisymmetric water flow toward a single root (at the mesoscopic scale). In the present study, three approximate solutions of mesoscopic root water uptake - finite difference approximation, steady-state solution, and steady-rate solution - are examined regarding their ability to capture the pressure head variations in the root vicinity. Insignificance of their differences when implemented in the macroscopic soil water flow model is demonstrated using the critical root water uptake concept. Subsequently, macroscopic simulations of coupled soil water flow and root water uptake are presented for a forest site under temperate humid climate. Predicted soil water pressure heads and actual transpiration rates are compared with observed data. Scenario simulations illustrate uncertainties associated with estimates of root geometrical and hydraulic properties. Regarding the actual transpiration prediction, the correct characterization of active root system geometry and hydraulic properties seems far more important than the choice of a particular mesoscopic model.

  2. Nitrogen and carbon uptake dynamics in Lake Superior

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Sterner, Robert W.; Finlay, Jacques C.

    2008-12-01

    Despite a fivefold rise in nitrate concentration over the last century, many fundamental aspects of Lake Superior's N and C cycles are still very poorly understood. We present here the first measurements of inorganic N uptake and in situ C uptake rates in Lake Superior, one of the largest lakes in the world. A profile of C uptake suggests that more than 95% of production occurs in the top 30 m with highest productivity to biomass ratio in the epilimnion. High C uptake:N uptake and particulate C: N ratio compared to the Redfield ratio (6.6) in the epilimnion suggests higher turnover rate of C compared to N in epilimnetic particles. Experiments performed over a range of typical environmental conditions suggest a strong temperature dependence of N uptake with maximum rates observed during the warmest stratified period. Lakewide N uptake estimates derived from a temperature-based model suggest that on an annual basis, uptake is considerably higher than total N inputs from outside the lake. This difference indicates that the lake is recycling N rapidly, leading to a shorter turnover time in the water column than previously assumed. The long-term buildup of nitrate in the lake has been hypothesized to arise from limited assimilation of nitrate entering the lake. In contrast, our results suggest that nitrate accumulating in the lake is a result of internal N cycling, a finding consistent with recent studies based on a nitrogen budget and NO3- stable isotope analyses.

  3. Nutrient uptake of peanut genotypes under different water regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought is a serious environmental stress limiting growth and productivity in peanut and other crops. Nutrient uptake of peanut is reduced under drought conditions, which reduces yield. The objectives of this study were to investigate nutrient uptake of peanut genotypes in response to drought and ...

  4. Liver uptake on bone scanning: a diagnostic algorithm.

    PubMed

    Al-Katib, Sayf; Al-Faham, Zaid; Balon, Helena

    2015-06-01

    In this report, we present a case of liver uptake seen on a bone scan that was due to diffuse metastatic disease from breast carcinoma. We discuss possible etiologies for the uptake and offer an algorithm to narrow the differential diagnosis.

  5. Increased Brain Fatty Acid Uptake in Metabolic Syndrome

    PubMed Central

    Karmi, Anna; Iozzo, Patricia; Viljanen, Antti; Hirvonen, Jussi; Fielding, Barbara A.; Virtanen, Kirsi; Oikonen, Vesa; Kemppainen, Jukka; Viljanen, Tapio; Guiducci, Letizia; Haaparanta-Solin, Merja; Någren, Kjell; Solin, Olof; Nuutila, Pirjo

    2010-01-01

    OBJECTIVE To test whether brain fatty acid uptake is enhanced in obese subjects with metabolic syndrome (MS) and whether weight reduction modifies it. RESEARCH DESIGN AND METHODS We measured brain fatty acid uptake in a group of 23 patients with MS and 7 age-matched healthy control subjects during fasting conditions using positron emission tomography (PET) with [11C]-palmitate and [18F]fluoro-6-thia-heptadecanoic acid ([18F]-FTHA). Sixteen MS subjects were restudied after 6 weeks of very low calorie diet intervention. RESULTS At baseline, brain global fatty acid uptake derived from [18F]-FTHA was 50% higher in patients with MS compared with control subjects. The mean percentage increment was 130% in the white matter, 47% in the gray matter, and uniform across brain regions. In the MS group, the nonoxidized fraction measured using [11C]-palmitate was 86% higher. Brain fatty acid uptake measured with [18F]-FTHA-PET was associated with age, fasting serum insulin, and homeostasis model assessment (HOMA) index. Both total and nonoxidized fractions of fatty acid uptake were associated with BMI. Rapid weight reduction decreased brain fatty acid uptake by 17%. CONCLUSIONS To our knowledge, this is the first study on humans to observe enhanced brain fatty acid uptake in patients with MS. Both fatty acid uptake and accumulation appear to be increased in MS patients and reversed by weight reduction. PMID:20566663

  6. Carbon uptake by karsts in the Houzhai Basin, southwest China

    NASA Astrophysics Data System (ADS)

    Yan, Junhua; Wang, Y. P.; Zhou, Guoyi; Li, Shenggong; Yu, Guirui; Li, Kun

    2011-12-01

    Using an estimated bicarbonate concentration ([HCO3-]) in water and discharge rates of surface water and underground water from the Houzhai Basin, southwest China, from 1986 to 2007, we estimate that the mean carbon uptake rate was 20.7 g C m-2 yr-1. The surface water and underground water contribute about equally to the total carbon uptake from 1986 to 2007. About 97% of the interannual variation of annual carbon uptake can be explained by the discharge rate. Within a year, the net carbon uptake rate by karst during the wet season (May-October) was found to be about 2.4 times that during the dry season (November-April). If the seasonal variations of discharge rate and bicarbonate concentrations are not accounted for, estimates of annual net carbon uptake by karst can be biased by >25%, but that bias becomes very small (<5%) when averaged from 1986 to 2007 for the Houzhai Basin. We also found that one of the empirical models as used in global modeling overestimated the net carbon uptake by karst at Houzhai Basin by 29%. Carbon uptake from chemical weathering of all karsts in China is estimated to be about 12 Tg C yr-1 at present (1 Tg = 1012 g), or about 57% of the rate of net carbon accumulated in the forest biomass from 1981 to 1998 in China; we therefore recommend the inclusion of carbon uptake from chemical weathering in the regional carbon budget of China.

  7. UPTAKE OF IONIZABLE ORGANIC CHEMICALS AT FISH GILLS

    EPA Science Inventory

    Uptake of organic acids by fish, and their toxicity, generally decrease with increasing pH above the pK, presumably due to neutral forms of such chemicals being more readily adsorbed than their ionized forms. However, uptake usually exceeds that expected based just on the concent...

  8. Matrix stiffness affects endocytic uptake of MK2-inhibitor peptides.

    PubMed

    Brugnano, Jamie L; Panitch, Alyssa

    2014-01-01

    In this study, the role of substrate stiffness on the endocytic uptake of a cell-penetrating peptide was investigated. The cell-penetrating peptide, an inhibitor of mitogen-activated protein kinase activated protein kinase II (MK2), enters a primary mesothelial cell line predominantly through caveolae. Using tissue culture polystyrene and polyacrylamide gels of varying stiffness for cell culture, and flow cytometry quantification and enzyme-linked immunoassays (ELISA) for uptake assays, we showed that the amount of uptake of the peptide is increased on soft substrates. Further, peptide uptake per cell increased at lower cell density. The improved uptake seen on soft substrates in vitro better correlates with in vivo functional studies where 10-100 µM concentrations of the MK2 inhibitor cell penetrating peptide demonstrated functional activity in several disease models. Additional characterization showed actin polymerization did not affect uptake, while microtubule polymerization had a profound effect on uptake. This work demonstrates that cell culture substrate stiffness can play a role in endocytic uptake, and may be an important consideration to improve correlations between in vitro and in vivo drug efficacy.

  9. Matrix Stiffness Affects Endocytic Uptake of MK2-Inhibitor Peptides

    PubMed Central

    Brugnano, Jamie L.; Panitch, Alyssa

    2014-01-01

    In this study, the role of substrate stiffness on the endocytic uptake of a cell-penetrating peptide was investigated. The cell-penetrating peptide, an inhibitor of mitogen-activated protein kinase activated protein kinase II (MK2), enters a primary mesothelial cell line predominantly through caveolae. Using tissue culture polystyrene and polyacrylamide gels of varying stiffness for cell culture, and flow cytometry quantification and enzyme-linked immunoassays (ELISA) for uptake assays, we showed that the amount of uptake of the peptide is increased on soft substrates. Further, peptide uptake per cell increased at lower cell density. The improved uptake seen on soft substrates in vitro better correlates with in vivo functional studies where 10–100 µM concentrations of the MK2 inhibitor cell penetrating peptide demonstrated functional activity in several disease models. Additional characterization showed actin polymerization did not affect uptake, while microtubule polymerization had a profound effect on uptake. This work demonstrates that cell culture substrate stiffness can play a role in endocytic uptake, and may be an important consideration to improve correlations between in vitro and in vivo drug efficacy. PMID:24400117

  10. Nucleic acids encoding metal uptake transporters and their uses

    DOEpatents

    Schroeder, Julian I.; Antosiewicz, Danuta M.; Schachtman, Daniel P.; Clemens, Stephan

    1999-01-01

    The invention provides LCT1 nucleic acids which encode metal ion uptake transporters. The invention also provides methods of modulating heavy metal and alkali metal uptake in plants. The methods involve producing transgenic plants comprising a recombinant expression cassette containing an LCT1 nucleic acid linked to a plant promoter.

  11. Uptake coefficients for biosolids-amended dryland winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biosolids regulations developed in the United States employed risk assessment impacts of trace element additions on plant uptake. The US Environmental Protection Agency adapted the uptake coefficient (ratio of plant concentration to quantity of element added) when developing limitations on selected...

  12. Methionine Uptake and Required Radiation Dose to Control Glioblastoma

    SciTech Connect

    Iuchi, Toshihiko; Hatano, Kazuo; Uchino, Yoshio; Itami, Makiko; Hasegawa, Yuzo; Kawasaki, Koichiro; Sakaida, Tsukasa; Hara, Ryusuke

    2015-09-01

    Purpose: The purpose of this study was to retrospectively assess the feasibility of radiation therapy planning for glioblastoma multiforme (GBM) based on the use of methionine (MET) positron emission tomography (PET), and the correlation among MET uptake, radiation dose, and tumor control. Methods and Materials: Twenty-two patients with GBM who underwent MET-PET prior to radiation therapy were enrolled. MET uptake in 30 regions of interest (ROIs) from 22 GBMs, biologically effective doses (BEDs) for the ROIs and their ratios (MET uptake:BED) were compared in terms of whether the ROIs were controlled for >12 months. Results: MET uptake was significantly correlated with tumor control (odds ratio [OR], 10.0; P=.005); however, there was a higher level of correlation between MET uptake:BED ratio and tumor control (OR, 40.0; P<.0001). These data indicated that the required BEDs for controlling the ROIs could be predicted in terms of MET uptake; BED could be calculated as [34.0 × MET uptake] Gy from the optimal threshold of the MET uptake:BED ratio for tumor control. Conclusions: Target delineation based on MET-PET was demonstrated to be feasible for radiation therapy treatment planning. MET-PET could not only provide precise visualization of infiltrating tumor cells but also predict the required radiation doses to control target regions.

  13. Lung uptake of thallium-201: a marker of defect reversibility?

    NASA Astrophysics Data System (ADS)

    Sanderson, R.; Woldman, S.; McCurrach, G.; Martin, W.; Hutton, I.

    1998-06-01

    High lung uptake of thallium-201 at stress is reported to be associated with a large number of perfusion defects and poor prognosis. This study was performed to assess whether the reversibility of stress perfusion defects was related to lung uptake. Gated planar thallium scans at stress and at redistribution from 102 consecutive patients with essentially normal left ventricular ejection fraction (using gated blood pool ventriculography) were graded in terms of defect size. Lung and myocardial uptake of thallium were quantitated by region of interest methods relative to the given activity in a previously validated method. There was no significant correlation (non-parametric) between lung uptake and degree of redistribution (). There was a weak but positive correlation between lung uptake and defect size (). Both exercise time and double product showed a negative correlation with lung uptake (e.g. for double product, ). In conclusion, contrary to our expectation, lung uptake is not related to the degree of redistribution. High lung uptake seems to reflect poor cardiovascular reserve.

  14. Concanavalin A-stimulated Ca2+ uptake in rat splenocytes.

    PubMed

    Larner, A; Rebhun, L I; Larner, J; Oron, Y

    1980-11-20

    Commercially available concanavalin A binds Ca2+ with high apparent affinity. In order to dissociate concanavalin A stimulated Ca2+ uptake (defined as an increased association of 45Ca2+ with cells) in rat splenocytes and Ca2+ binding to cell-bound concanavalin A, conditions were developed to remove more than 75% of the bound concanavalin A. Under these conditions concanavalin A treated cells showed a considerable increase in 45Ca2+ uptake over control. The concanavalin A stimulated uptake of 45Ca2+ occurred within minutes, and required concentrations of concanavalin A which promoted [3H]thymidine uptake into these cells. Succinyl concanavalin A was less potent in promoting Ca2+ uptake than concanavalin A. Sodium periodate inhibited Ca2+ uptake at concentrations which promoted 3H-thymidine incorporation into splenocytes. It is concluded that concanavalin A promotes Ca2+ uptake which is not due to binding of 45Ca2+ to concanavalin A. Although the concanavalin A-promoted Ca2+ uptake occurs at lectin concentrations that cause lymphocyte proliferation as measured by 3H-thymidine incorporation, the role of Ca2+ in this event remains unclear.

  15. Kinetics and mechanism of DNA uptake into the cell nucleus

    PubMed Central

    Salman, H.; Zbaida, D.; Rabin, Y.; Chatenay, D.; Elbaum, M.

    2001-01-01

    Gene transfer to eukaryotic cells requires the uptake of exogenous DNA into the cell nucleus. Except during mitosis, molecular access to the nuclear interior is limited to passage through the nuclear pores. Here we demonstrate the nuclear uptake of extended linear DNA molecules by a combination of fluorescence microscopy and single-molecule manipulation techniques, using the latter to follow uptake kinetics of individual molecules in real time. The assays were carried out on nuclei reconstituted in vitro from extracts of Xenopus eggs, which provide both a complete complement of biochemical factors involved in nuclear protein import, and unobstructed access to the nuclear pores. We find that uptake of DNA is independent of ATP or GTP hydrolysis, but is blocked by wheat germ agglutinin. The kinetics are much slower than would be expected from hydrodynamic considerations. A fit of the data to a simple model suggests femto-Newton forces and a large friction relevant to the uptake process. PMID:11390964

  16. Uptake of immunisation in district health authorities in England

    PubMed Central

    Jarman, Brian; Bosanquet, Nick; Rice, Peter; Dollimore, Nicola; Leese, Brenda

    1988-01-01

    The uptakes of immunisation in the district health authorities in England were studied for the years 1983-5. Multiple regression analysis showed that the factors significantly associated with a low uptake of immunisation were mainly related to social conditions, particularly overcrowding of households and population density. Of the service factors, high proportions of elderly and singlehanded general practitioners and high average list sizes were also associated with a low uptake of immunisation in some of the analyses. The results suggest that the measures outlined in the government's white paper on improving primary health care services are likely to lead to improved uptakes of immunisation. If, however, the uptakes of immunisation are used as a measure of standards of the services provided they should first be adjusted to control for variations in social conditions, and the quality of vaccination data would have to be improved. PMID:3250552

  17. Interleukin-15 receptor is essential to facilitate GABA transmission and hippocampal dependent memory

    PubMed Central

    He, Yi; Wu, Xiaojun; Hsuchou, Hung; Kastin, Abba J.; Khan, Reas S.; Pistell, Paul J.; Wang, Wei-Hsung; Feng, Jiming; Li, Zengbiao; Guo, Xiaochuan; Pan, Weihong

    2010-01-01

    Interleukin-15 (IL15) is a cytokine produced by normal brain, but the functions of the IL15 system in normal adults are not yet clear. The hypothesis that the hippocampal IL15 system is essential for memory consolidation was tested by use of IL15Rα knockout mice in behavioral, biochemical, immunohistological, and electron microscopic analyses. The knockout mice showed deficits in memory, determined by the Stone T-maze and fear conditioning. In their hippocampi, the concentration of γ-aminobutyric acid (GABA) was significantly lower. There were region specific changes of the GABA synthesizing enzyme glutamic acid decarboxidase (GAD), with increased GAD-67 immunopositive interneurons in the stratum oriens of the CA1 region of the hippocampus, accompanied by non-significant reduction of GAD-67 synapses in the CA3 region. Western blotting showed an increase of GAD-65, but not GAD-67, in the hippocampal homogenate. The ultrastructure of the hippocampus remained intact in the knockout mice. To further test the hypothesis that IL15 directly modulates GABA turnover by reuptake mechanisms, the dose-response relationship of IL15 on 3H-GABA uptake was determined in two neuronal cell lines. The effective and non-toxic dose was further used in the synaptosomal uptake studies. IL15 decreased the uptake of 3H-GABA in synaptosomes from the forebrain of wildtype mice. Consistent with this, IL15Rα knockout mice had increased synaptosomal uptake of 3H-GABA. Overall, the results show novel functions of a unique cytokine in normal hippocampal activity by regulating GABA transmission. PMID:20357123

  18. Forage uptake of uranium series radionuclides in the vicinity of the anaconda uranium mill

    SciTech Connect

    Rayno, D.R.; Momeni, M.H.; Sabau, C.

    1980-01-01

    Radiochemical analysis was performed on samples of soil and eight species of common vegetation growing on the Anaconda uranium mill site, located in New Mexico. The concentrations of the long-lived radionuclides U-238, U-234, Th-230, Ra-226, and Pb-210 in these forage plants were determined. The sampling procedures and analytical laboratory methods used are described. The highest radionuclide concentration found in a forage species was 130 pCi of Ra-226 per gram dry weight for grass growing on the main tailings pile at Anaconda, where the surface soil activity of Ra-226 was 236 pCi/g. A comparison of shoots activity with that of roots and soil was used to determine a distribution index and uptake coefficient for each species. The distribution index, the ratio of root activity to shoot activity, ranged from 0.30 (Th-230) in galleta grass (Hilaria jamesii) to 38.0 (Ra-226) in Indian ricegrass (Oryzopsis hymenoides). In nearly all instances, the roots contained higher radionuclide concentrations. The uptake coefficient, the ratio of vegetation activity to soil activity, ranged from 0.69 (U-238) in Indian ricegrass roots to 0.01 (U-238) in four-wing saltbush (Atriplex canescans) shoots. The range of radionuclide concentrations in plants growing on the Anaconda mill site is compared to that in vegetation from a control site 20 km away.

  19. Coupling Physiology and Gene Regulation in Bacteria: The Phosphotransferase Sugar Uptake System Delivers the Signals

    NASA Astrophysics Data System (ADS)

    Stülke, Jörg; Hillen, Wolfgang

    In many bacteria a crucial link between metabolism and regulation of catabolic genes is based on the phosphotransferase sugar uptake system (PTS). We summarize the mechanisms of the signaling pathways originating from PTS and leading to regulation of transcription. A protein domain, called PTS regulation domain (PRD), is linked to many antiterminators and transcriptional activators and regulates their activity depending on its state of phosphorylation. Two sites can be phosphorylated in most PRDs: HPr-dependent modification at one site leads to activation while enzyme II dependent phosphorylation of the other site renders it inactive. In addition, PTS components are used to generate cofactors for regulators of transcription. The paradigm is the enzyme II dependent activity of adenylate cyclase determining the cyclic AMP level in Escherichia coli and thereby the activity of the catabolite activator protein. In many gram-positive bacteria catabolite repression is mediated by the catabolite control protein CcpA, which requires HPr Ser-46 phosphate as a cofactor to regulate transcription of catabolic genes. HPr Ser-46 phosphate is produced by HPr kinase, the activity of which is under metabolic control via the concentrations of glycolytic intermediates. These recent results establish a multifaceted regulatory role for PTS in addition to its well-established function in active sugar uptake.

  20. Modulation of Glycosaminoglycans Affects PrPSc Metabolism but Does Not Block PrPSc Uptake

    PubMed Central

    Wolf, Hanna; Graßmann, Andrea; Bester, Romina; Hossinger, André; Möhl, Christoph; Paulsen, Lydia; Groschup, Martin H.; Schätzl, Hermann

    2015-01-01

    ABSTRACT Mammalian prions are unconventional infectious agents composed primarily of the misfolded aggregated host prion protein PrP, termed PrPSc. Prions propagate by the recruitment and conformational conversion of cellular prion protein into abnormal prion aggregates on the cell surface or along the endocytic pathway. Cellular glycosaminoglycans have been implicated as the first attachment sites for prions and cofactors for cellular prion replication. Glycosaminoglycan mimetics and obstruction of glycosaminoglycan sulfation affect prion replication, but the inhibitory effects on different strains and different stages of the cell infection have not been thoroughly addressed. We examined the effects of a glycosaminoglycan mimetic and undersulfation on cellular prion protein metabolism, prion uptake, and the establishment of productive infections in L929 cells by two mouse-adapted prion strains. Surprisingly, both treatments reduced endogenous sulfated glycosaminoglycans but had divergent effects on cellular PrP levels. Chemical or genetic manipulation of glycosaminoglycans did not prevent PrPSc uptake, arguing against their roles as essential prion attachment sites. However, both treatments effectively antagonized de novo prion infection independently of the prion strain and reduced PrPSc formation in chronically infected cells. Our results demonstrate that sulfated glycosaminoglycans are dispensable for prion internalization but play a pivotal role in persistently maintained PrPSc formation independent of the prion strain. IMPORTANCE Recently, glycosaminoglycans (GAGs) became the focus of neurodegenerative disease research as general attachment sites for cell invasion by pathogenic protein aggregates. GAGs influence amyloid formation in vitro. GAGs are also found in intra- and extracellular amyloid deposits. In light of the essential role GAGs play in proteinopathies, understanding the effects of GAGs on protein aggregation and aggregate dissemination is crucial

  1. N-isopropyl-(/sup 123/I)p-iodoamphetamine: single-pass brain uptake and washout; binding to brain synaptosomes; and localization in dog and monkey brain

    SciTech Connect

    Winchell, H.S.; Horst, W.D.; Braun, L.; Oldendorf, W.H.; Hattner, R.; Parker, H.

    1980-10-01

    The kinetics of N-isopropyl-p-(/sup 123/I)iodoamphetamine in rat brains were determined by serial measurements of brain uptake index (BUI) after intracarotid injection; also studied were its effects on amine uptake and release in rat's brain cortical synaptosomes; and its in vivo distribution in the dog and monkey. No specific localization in brain nuclei of the dog was seen, but there was progressive accumulation in the eyes. Rapid initial brain uptake in the ketamine-sedated monkey was noted, and further slow brain uptake occurred during the next 20 min but without retinal localization. High levels of brain activity were maintained for several hours. The quantitative initial single-pass clearance of the agent in the brain suggests its use in evaluation of regional brain perfusion. Its interaction with brain amine-binding sites suggests its possible application in studies of cerebral amine metabolism.

  2. Cellular Uptake and Intracellular Trafficking of Oligonucleotides: Implications for Oligonucleotide Pharmacology

    PubMed Central

    Ming, Xin; Carver, Kyle; Laing, Brian

    2014-01-01

    One of the major constraints on the therapeutic use of oligonucleotides is inefficient delivery to their sites of action in the cytosol or nucleus. Recently it has become evident that the pathways of cellular uptake and intracellular trafficking of oligonucleotides can strongly influence their pharmacological actions. Here we provide background information on the basic processes of endocytosis and trafficking and then review recent literature on targeted delivery and subcellular trafficking of oligonucleotides in that context. A variety of approaches including molecular scale ligand-oligonucleotide conjugates, ligand-targeted nanocarriers, and the use of small molecules to enhance oligonucleotide effects are discussed. PMID:24383421

  3. Amino acid uptake in rust fungi.

    PubMed

    Struck, Christine

    2015-01-01

    The plant pathogenic rust fungi colonize leaf tissue and feed off their host plants without killing them. Certain economically important species of different genera such as Melampsora, Phakopsora, Puccinia, or Uromyces are extensively studied for resolving the mechanisms of the obligate biotrophy. As obligate parasites rust fungi only can complete their life cycle on living hosts where they grow through the leaf tissue by developing an extended network of intercellular hyphae from which intracellular haustoria are differentiated. Haustoria are involved in key functions of the obligate biotrophic lifestyle: suppressing host defense responses and acquiring nutrients. This review provides a survey of rust fungi nitrogen nutrition with special emphasis on amino acid uptake. A variety of sequences of amino acid transporter genes of rust fungi have been published; however, transport activity of only three in planta highly up-regulated amino acid permeases have been characterized. Functional and immunohistochemical investigations have shown the specificity and localization of these transporters. Sequence data of various genome projects allowed identification of numerous rust amino acid transporter genes. An in silico analysis reveals that these genes can be classified into different transporter families. In addition, genetic and molecular data of amino acid transporters have provided new insights in the corresponding metabolic pathways.

  4. Selenium uptake by sulfur-accumulating bacteria

    NASA Astrophysics Data System (ADS)

    Nelson, Douglas C.; Casey, William H.; Sison, Jennette D.; Mack, E. Erin; Ahmad, Azeem; Pollack, Jeffrey S.

    1996-09-01

    Selenium is a trace metal in many rock-forming minerals but is a major environmental contaminant worldwide. Uptake of selenium by S-accumulating bacteria was examined in both pure cultures of Chromatium vinosum and in co-culture with Desulfovibrio desulfuricans. We used dual cultures including these bacteria to concentrate selenium into intracellular globules. The bacterium D. desulfuricans reduces sulfate [SO 42- (aq)] to sulfide [H 2S(aq)] and also reduces selenate [SeO 42- (aq)] to selenide [H 2Se (aq)]. Once reduced, sulfide is enzymatically oxidized and formed into intracellular globules by C. vinosum. We found that the selenium also forms an intercellular solid but the reaction is thermodynamically driven and proceeds by reducing S° (s) with H 2Se(aq). Relative to the initial molar ratio of selenate and sulfate in the medium, selenium is concentrated 4.5 to 32-fold in the globules. Because solid selenium is so much more stable than sulfur at growth conditions, other S-depositing bacteria, such as Beggiatoa and Chlorobium, should also concentrate selenium via this reaction, providing a strategy for eliminating contamination or for concentrating low natural levels into a usable form.

  5. Cellular uptake: lessons from supramolecular organic chemistry.

    PubMed

    Gasparini, Giulio; Bang, Eun-Kyoung; Montenegro, Javier; Matile, Stefan

    2015-07-01

    The objective of this Feature Article is to reflect on the importance of established and emerging principles of supramolecular organic chemistry to address one of the most persistent problems in life sciences. The main topic is dynamic covalent chemistry on cell surfaces, particularly disulfide exchange for thiol-mediated uptake. Examples of boronate and hydrazone exchange are added for contrast, comparison and completion. Of equal importance are the discussions of proximity effects in polyions and counterion hopping, and more recent highlights on ring tension and ion pair-π interactions. These lessons from supramolecular organic chemistry apply to cell-penetrating peptides, particularly the origin of "arginine magic" and the "pyrenebutyrate trick," and the currently emerging complementary "disulfide magic" with cell-penetrating poly(disulfide)s. They further extend to the voltage gating of neuronal potassium channels, gene transfection, and the delivery of siRNA. The collected examples illustrate that the input from conceptually innovative chemistry is essential to address the true challenges in biology beyond incremental progress and random screening.

  6. New nitrogen uptake strategy: specialized snow roots.

    PubMed

    Onipchenko, Vladimir G; Makarov, Mikhail I; van Logtestijn, Richard S P; Ivanov, Viktor B; Akhmetzhanova, Assem A; Tekeev, Dzhamal K; Ermak, Anton A; Salpagarova, Fatima S; Kozhevnikova, Anna D; Cornelissen, Johannes H C

    2009-08-01

    The evolution of plants has yielded a wealth of adaptations for the acquisition of key mineral nutrients. These include the structure, physiology and positioning of root systems. We report the discovery of specialized snow roots as a plant strategy to cope with the very short season for nutrient uptake and growth in alpine snow-beds, i.e. patches in the landscape that remain snow-covered well into the summer. We provide anatomical, chemical and experimental (15)N isotope tracking evidence that the Caucasian snow-bed plant Corydalis conorhiza forms extensive networks of specialized above-ground roots, which grow against gravity to acquire nitrogen directly from within snow packs. Snow roots capture nitrogen that would otherwise partly run off down-slope over a frozen surface, thereby helping to nourish these alpine ecosystems. Climate warming is changing and will change mountain snow regimes, while large-scale anthropogenic N deposition has increased snow N contents. These global changes are likely to impact on the distribution, abundance and functional significance of snow roots.

  7. Spiperone: evidence for uptake into secretory granules.

    PubMed Central

    Dannies, P S; Rudnick, M S; Fishkes, H; Rudnick, G

    1984-01-01

    Spiperone, a dopamine antagonist widely used as a specific ligand for dopamine and serotonin receptors, is actively accumulated into the F4C1 strain of rat pituitary tumor cells. The accumulation of 10 nM [3H]spiperone was linear for 3 min and reached a steady state after 10 min. Spiperone accumulation was reduced 50% by preincubation with 5 microM reserpine, an inhibitor of biogenic amine transport into secretory granules, and was also blocked by monensin and ammonium chloride, both of which increase the pH of intracellular storage organelles. Uptake was not affected by replacing sodium in the buffer with lithium at equimolar concentrations. Spiperone at 1 microM inhibited by over 50% serotonin transport into membrane vesicles isolated from platelet dense granules; this concentration inhibited the Na+-dependent plasma membrane transport system less than 10%. The data indicate spiperone specifically interacts with the secretory granule amine transport system and suggest that this transport system is found in the F4C1 pituitary cell strain as well as in platelets and neurons. The data also suggest that experiments utilizing spiperone to measure dopamine and serotonin receptors be interpreted with caution. PMID:6584920

  8. Vascular renin and hypertension. Uptake versus synthesis.

    PubMed

    Swales, J D; Samani, N J

    1990-11-01

    Conventional radioimmunoassay techniques demonstrated in the aortic wall a renin-like activity which is derived from plasma but has a longer half-life than plasma renin. Blood pressure elevation after renin injection into nephrectomized rats correlates better with aortic renin than with plasma renin. Vascular and other extrarenal tissue can also synthesize renin. Using a ribonuclease protection technique for the detection of renin messenger RNA we have been able to demonstrate that a wide variety of extrarenal tissues contain the renin message. In at least two of these, the brain and the liver, renin messenger RNA levels are unaffected by changes in dietary salt or by changes in systemic blood pressure. Functional studies using isolated human resistance vessels also demonstrate the presence of renin-like activity by a contractile response to added renin substrate. It is suggested that extrarenal tissues therefore contain renin-like activity derived both from uptake and from local synthesis. These systems may be regulated in different ways and may carry out different functions.

  9. Nonstomatal versus stomatal uptake of atmospheric mercury.

    PubMed

    Stamenkovic, Jelena; Gustin, Mae S

    2009-03-01

    Atmospheric constituents may be deposited to and incorporated into plant leaves, with gases entering via stomata, and gas and particles being sorbed at the surface and in some cases traversing the cuticle, possibly reaching the epidermis. Plants are known to be a sink for atmospheric mercury (Hg), and the current paradigm is that uptake of gaseous elemental Hg occurs by way of the stomata. Four plant species, Rudbeckia hirta, Sorghastrum nutans, Andropogon gerardii, and Populus tremuloides, were exposed to air from different sources and with different Hg and CO2 concentrations in light and dark within a gas exchange chamber at approximately 25% relative humidity. Data showed that Hg concentration and air source had a significant effect (p < 0.001) on leaf-atmosphere Hg flux, with more deposition to the leaf occurring in elevated-Hg air, and in scrubbed air compared to ambient air. Deposition also occurred during dark and elevated CO2 exposures, when stomatal conductance was reduced. These observations and the fact that limited or no Hg emission occurred after deposition of atmospheric Hg suggests that the nonstomatal pathway may be an important route of foliar accumulation of atmospheric Hg.

  10. Organochlorine (chlordecone) uptake by root vegetables.

    PubMed

    Florence, Clostre; Philippe, Letourmy; Magalie, Lesueur-Jannoyer

    2015-01-01

    Chlordecone, an organochlorine insecticide, continues to pollute soils in the French West Indies. The main source of human exposure to this pollutant is food. Root vegetables, which are staple foods in tropical regions, can be highly contaminated and are thus a very effective lever for action to reduce consumer exposure. We analyzed chlordecone contamination in three root vegetables, yam, dasheen and sweet potato, which are among the main sources of chlordecone exposure in food in the French West Indies. All soil types do not have the same potential for the contamination of root vegetables, allophanic andosols being two to ten times less contaminating than non-allophanic nitisols and ferralsols. This difference was only partially explained by the higher OC content in allophanic soils. Dasheen corms were shown to accumulate more chlordecone than yam and sweet potato tubers. The physiological nature of the root vegetable may explain this difference. Our results are in good agreement with the hypothesis that chlordecone uptake by root vegetables is based on passive and diffusive processes and limited by transport and dilution during growth.

  11. Iron uptake and metabolism in pseudomonads.

    PubMed

    Cornelis, Pierre

    2010-05-01

    Pseudomonads are ubiquitous Gram-negative gamma proteobacteria known for their extreme versatility and adaptability. Some are plant pathogens (Pseudomonas syringae) which have to survive on the surface of leaves while others can colonize the rhizosphere or survive in soil (Pseudomonas fluorescens, Pseudomonas putida), and one species, Pseudomonas entomophila, is an insect pathogen. The most investigated species, Pseudomonas aeruginosa, is known to be an opportunistic pathogen able to infect plants, nematodes, insects, and mammals, including humans. Like for other bacteria, iron is a key nutrient for pseudomonads. The fluorescent pseudomonads produce siderophores, the best known being the fluorescent high-affinity peptidic pyoverdines. Often diverse secondary siderophores of lower affinity are produced as well (pyochelin, pseudomonin, corrugatins and ornicorrugatins, yersiniabactin, and thioquinolobactin). Reflecting their large capacity of adaptation to changing environment and niche colonization, pseudomonads are able to obtain their iron from heme or from siderophores produced by other microorganisms (xenosiderophores) via the expression of outer membrane TonB-dependent receptors. As expected, iron uptake is exquisitely and hierarchically regulated in these bacteria. In this short review, the diversity of siderophores produced, receptors, and finally the way iron homeostasis is regulated in P. aeruginosa, P. syringae, P. putida, and P. fluorescens, will be presented and, when possible, put in relation with the lifestyle and the ecological niche. PMID:20352420

  12. Bioenergetics and solute uptake under extreme conditions.

    PubMed

    Albers, S V; Van de Vossenberg, J L; Driessen, A J; Konings, W N

    2001-10-01

    The ion and particularly the proton and sodium ion permeabilities of cytoplasmic membranes play crucial roles in the bioenergetics of microorganisms. The proton and sodium permeabilities of membranes increase with temperature. Psychrophilic and mesophilic bacteria and mesophilic, (hyper)thermophilic, and halophilic archaea are capable of adjusting the lipid composition of their membranes in such a way that the proton permeability at the respective growth temperature remains constant (homeoproton permeability). Thermophilic bacteria are an exception. They rely on the less permeable sodium ions to generate a sodium motive force, which is subsequently used to drive energy-requiring membrane-bound processes. Transport of solutes across bacterial and archaeal membranes is mainly catalyzed by primary ATP-driven transport systems or by proton- or sodium-motive-force-driven secondary transport systems. Unlike most bacteria, hyperthermophilic bacteria and archaea prefer primary uptake systems. Several high-affinity ATP-binding cassette (ABC) transporters for sugars from hyperthermophiles have been identified and characterized. The activities of these ABC transporters allow these organisms to thrive in their nutrient-poor environments.

  13. Isotopic signatures of H2 and CO uptake and emissions by soil

    NASA Astrophysics Data System (ADS)

    Popa, Maria Elena; Chen, Qianjie; Röckmann, Thomas

    2016-04-01

    We performed soil chamber experiments in order to determine the isotopic signatures of the exchange of H2 and CO between soil and atmosphere. The experiments took place at two sites in the Netherlands, a forest (Speuld) and a grass field (Cabauw). Flask samples were filled from the soil chamber, and then analyzed in the laboratory for δD in H2 and δ13C and δ18O in CO. The isotope results prove that, for both species, uptake and emission occur simultaneously regardless of the direction of the net flux. We were able to determine separately the isotopic effects of the two fluxes. For both H2 and CO, soil uptake is associated with a small positive fractionation (the lighter molecule is taken up faster). The soil uptake fractionation (α = kheavy/klight) was 0.945 ± 0.004 for H2; for CO, the fractionation was 0.992 for 13C and 0.985 for 18O. The isotopic composition of the H2 emitted from the grassland was -530 ± 40 ‰, less depleted that what is expected from the isotopic equilibrium of H2 with water. For CO, the isotopic composition of the soil emission is depleted in 13C compared to atmospheric CO, and lower than the average isotopic composition of plant or soil organic matter.

  14. Uptake of polychlorinated biphenyls and organochlorine pesticides from soil and air into radishes (Raphanus sativus).

    PubMed

    Mikes, Ondrej; Cupr, Pavel; Trapp, Stefan; Klanova, Jana

    2009-02-01

    Uptake of organochlorine pesticides and polychlorinated biphenyls from soil and air into radishes was measured at a heavily contaminated field site. The highest contaminant concentrations were found for DDT and its metabolites, and for beta-hexachlorocyclohexane. Bioconcentration factor (BCF, defined as a ratio between the contaminant concentration in the plant tissue and concentration in soil) was determined for roots, edible bulbs and shoots. Root BCF values were constant and not correlated to log K(OW). A negative correlation between BCF and log K(OW) was found for edible bulbs. Shoot BCF values were rather constant and varied between 0.01 and 0.22. Resuspended soil particles may facilitate the transport of chemicals from soil to shoots. Elevated POP concentrations found in shoots of radishes grown in the control plot support the hypothesis that the uptake from air was more significant for shoots than the one from soil. The uptake of POPs from air was within the range of theoretical values predicted from log K(OA).

  15. The minute virus of mice exploits different endocytic pathways for cellular uptake

    SciTech Connect

    Garcin, Pierre O.; Panté, Nelly

    2015-08-15

    The minute virus of mice, prototype strain (MVMp), is a non-enveloped, single-stranded DNA virus of the family Parvoviridae. Unlike other parvoviruses, the mechanism of cellular uptake of MVMp has not been studied in detail. We analyzed MVMp endocytosis in mouse LA9 fibroblasts and a tumor cell line derived from epithelial–mesenchymal transition through polyomavirus middle T antigen transformation in transgenic mice. By a combination of immunofluorescence and electron microscopy, we found that MVMp endocytosis occurs at the leading edge of migrating cells in proximity to focal adhesion sites. By using drug inhibitors of various endocytic pathways together with immunofluorescence microscopy and flow cytometry analysis, we discovered that MVMp can use a number of endocytic pathways, depending on the host cell type. At least three different mechanisms were identified: clathrin-, caveolin-, and clathrin-independent carrier-mediated endocytosis, with the latter occurring in transformed cells but not in LA9 fibroblasts. - Highlights: • MVMp uptake takes place at the leading edge of migrating cells. • MVMp exploits a variety of endocytic pathways. • MVMp could use clathrin- and caveolin-mediated endocytosis. • MVMp could also use clathrin-independent carriers for cellular uptake.

  16. Structural basis for ligand and innate immunity factor uptake by the trypanosome haptoglobin-haemoglobin receptor.

    PubMed

    Lane-Serff, Harriet; MacGregor, Paula; Lowe, Edward D; Carrington, Mark; Higgins, Matthew K

    2014-12-12

    The haptoglobin-haemoglobin receptor (HpHbR) of African trypanosomes allows acquisition of haem and provides an uptake route for trypanolytic factor-1, a mediator of innate immunity against trypanosome infection. In this study, we report the structure of Trypanosoma brucei HpHbR in complex with human haptoglobin-haemoglobin (HpHb), revealing an elongated ligand-binding site that extends along its membrane distal half. This contacts haptoglobin and the β-subunit of haemoglobin, showing how the receptor selectively binds HpHb over individual components. Lateral mobility of the glycosylphosphatidylinositol-anchored HpHbR, and a ∼50° kink in the receptor, allows two receptors to simultaneously bind one HpHb dimer. Indeed, trypanosomes take up dimeric HpHb at significantly lower concentrations than monomeric HpHb, due to increased ligand avidity that comes from bivalent binding. The structure therefore reveals the molecular basis for ligand and innate immunity factor uptake by trypanosomes and identifies adaptations that allow efficient ligand uptake in the context of the complex trypanosome cell surface.

  17. Uptake of [3H]-nicotine and [3H]-noradrenaline by cultured chromaffin cells.

    PubMed Central

    Ceña, V.; García, A. G.; Montiel, C.; Sánchez-García, P.

    1984-01-01

    Three day-old cultured bovine adrenal chromaffin cells incubated at room temperature with Krebs-HEPES solution containing different concentrations of [3H]-nicotine, took up and retained increasing amounts of the drug by a mechanism that did not saturate. Concentrations of cold nicotine as high as 100 microM did not alter the amount of [3H]-nicotine retained by cells. Imipramine, cocaine, tetracaine or mecamylamine, at concentrations (10 microM) that blocked the catecholamine secretory effects of nicotine completely, did not modify the uptake of [3H]-nicotine. Both imipramine and cocaine drastically inhibited [3H]-noradrenaline uptake by cells in a concentration-dependent manner (IC50S of 0.08 and 1 microM, respectively). These data indicate that the secretory effects of nicotine are not coupled to its previous uptake into cells, and are evidence in favour of a site of action for nicotine located in or at the surface of the chromaffin cell membrane. PMID:6704577

  18. Structural basis for ligand and innate immunity factor uptake by the trypanosome haptoglobin-haemoglobin receptor

    PubMed Central

    Lane-Serff, Harriet; MacGregor, Paula; Lowe, Edward D; Carrington, Mark; Higgins, Matthew K

    2014-01-01

    The haptoglobin-haemoglobin receptor (HpHbR) of African trypanosomes allows acquisition of haem and provides an uptake route for trypanolytic factor-1, a mediator of innate immunity against trypanosome infection. In this study, we report the structure of Trypanosoma brucei HpHbR in complex with human haptoglobin-haemoglobin (HpHb), revealing an elongated ligand-binding site that extends along its membrane distal half. This contacts haptoglobin and the β-subunit of haemoglobin, showing how the receptor selectively binds HpHb over individual components. Lateral mobility of the glycosylphosphatidylinositol-anchored HpHbR, and a ∼50o kink in the receptor, allows two receptors to simultaneously bind one HpHb dimer. Indeed, trypanosomes take up dimeric HpHb at significantly lower concentrations than monomeric HpHb, due to increased ligand avidity that comes from bivalent binding. The structure therefore reveals the molecular basis for ligand and innate immunity factor uptake by trypanosomes and identifies adaptations that allow efficient ligand uptake in the context of the complex trypanosome cell surface. DOI: http://dx.doi.org/10.7554/eLife.05553.001 PMID:25497229

  19. BRAF inhibition decreases cellular glucose uptake in melanoma in association with reduction in cell volume

    PubMed Central

    Theodosakis, Nicholas; Held, Matthew A.; Marzuka-Alcala, Alexander; Meeth, Katrina M.; Micevic, Goran; Long, Georgina V.; Scolyer, Richard A.; Stern, David F.; Bosenberg, Marcus W.

    2015-01-01

    BRAF kinase inhibitors have dramatically impacted treatment of BRAFV600E/K-driven metastatic melanoma. Early responses assessed using [18F]fluorodeoxyglucose uptake-positron emission tomography (FDG-PET) have shown dramatic reduction of radiotracer signal within two weeks of treatment. Despite high response rates, relapse occurs in nearly all cases, frequently at sites of treated metastatic disease. It remains unclear whether initial loss of 18FDG uptake is due to tumor cell death or other reasons. Here we provide evidence of melanoma cell volume reduction in a patient cohort treated with BRAF inhibitors. We present data demonstrating that BRAF inhibition reduces melanoma glucose uptake per cell, but that this change is no longer significant following normalization for cell volume changes. We also demonstrate that volume normalization greatly reduces differences in transmembrane glucose transport and hexokinase-mediated phosphorylation. Mechanistic studies suggest that this loss of cell volume is due in large part to decreases in new protein translation as a consequence of vemurafenib treatment. Ultimately, our findings suggest that cell volume regulation constitutes an important physiologic parameter that may significantly contribute to radiographic changes observed in clinic. PMID:25948295

  20. Inhibition of Nitrate Transporter 1.1-Controlled Nitrate Uptake Reduces Cadmium Uptake in Arabidopsis1[C][W

    PubMed Central

    Mao, Qian Qian; Guan, Mei Yan; Lu, Kai Xing; Du, Shao Ting; Fan, Shi Kai; Ye, Yi-Quan; Lin, Xian Yong; Jin, Chong Wei

    2014-01-01

    Identification of mechanisms that decrease cadmium accumulation in plants is a prerequisite for minimizing dietary uptake of cadmium from contaminated crops. Here, we show that cadmium inhibits nitrate transporter 1.1 (NRT1.1)-mediated nitrate (NO3−) uptake in Arabidopsis (Arabidopsis thaliana) and impairs NO3− homeostasis in roots. In NO3−-containing medium, loss of NRT1.1 function in nrt1.1 mutants leads to decreased levels of cadmium and several other metals in both roots and shoots and results in better biomass production in the presence of cadmium, whereas in NO3−-free medium, no difference is seen between nrt1.1 mutants and wild-type plants. These results suggest that inhibition of NRT1.1 activity reduces cadmium uptake, thus enhancing cadmium tolerance in an NO3− uptake-dependent manner. Furthermore, using a treatment rotation system allowing synchronous uptake of NO3− and nutrient cations and asynchronous uptake of cadmium, the nrt1.1 mutants had similar cadmium levels to wild-type plants but lower levels of nutrient metals, whereas the opposite effect was seen using treatment rotation allowing synchronous uptake of NO3− and cadmium and asynchronous uptake of nutrient cations. We conclude that, although inhibition of NRT1.1-mediated NO3− uptake by cadmium might have negative effects on nitrogen nutrition in plants, it has a positive effect on cadmium detoxification by reducing cadmium entry into roots. NRT1.1 may regulate the uptake of cadmium and other cations by a common mechanism. PMID:25106820

  1. Close coupling between ammonium uptake by phytoplankton and excretion by Antarctic krill, Euphausia superba

    NASA Astrophysics Data System (ADS)

    Whitehouse, M. J.; Atkinson, A.; Rees, A. P.

    2011-07-01

    In this study we examined the hypothesis that, under conditions of replete macronutrients and iron in the Southern Ocean, phytoplankton abundance and specific N uptake rates are influenced strongly by the processes of grazing and NH 4 regeneration. NH 4 and NO 3 uptake rates by marine phytoplankton were measured to the northeast and northwest of the island of South Georgia during January-February 1998. Mean specific uptake rate for NO 3 ( vNO 3) was 0.0026 h -1 (range 0.0013-0.0065 h -1) and for NH 4 ( vNH 4) was 0.0097 h -1 (0.0014-0.0376 h -1). vNH 4 was related positively with NH 4 availability, which ranged from 0.1 to 1.5 mmol m -3 within the upper mixed layer. Ambient NH 4 concentrations and vNH 4 were both positively related to local krill biomass values, computed from mean values along acoustic transect segments within 2 km of the uptake measurement stations. These biomass values ranged from ˜1 g krill fresh mass m -2 in the northwest to >4 kg krill wet mass m -2 in the northeast. In contrast to the variability found with NH 4 concentrations and uptake rates, vNO 3 was more uniform across the sampling sites. Under these conditions, increasing NH 4 concentration appeared to represent an additional N resource. However, high vNH 4 tended to be found for stations with lower phytoplankton standing stocks, across a total range of 0.24-20 mg chlorophyll a m -3. These patterns suggest a coupling between phytoplankton biomass, vNH 4 and krill in this region of variable but high krill biomass. Locally high concentrations of krill in parts of the study area appeared to have two opposing effects. On the one hand they could graze down phytoplankton stocks, but on the other hand, their NH 4 excretion supported enhanced uptake rates by the remaining, ungrazed cells.

  2. Relative activities on and uptake by human blood platelets of 5-hydroxytryptamine and several analogues

    PubMed Central

    Born, G. V. R.; Juengjaroen, Kanchana; Michal, F.

    1972-01-01

    1. The specificity of platelet receptor sites for 5-HT uptake and for the rapid morphological change and aggregation was investigated with 5-hydroxy-tryptamine (5-HT) and seventeen analogues as well as with some antagonists of 5-HT. 2. The analogues, with the exception of 5-hydroxy-N'N'-dibutyltryptamine, caused the rapid morphological change in platelets. In concentrations below those needed to produce the agonistic action (viz. 0.05-2.0 μM), these analogues themselves inhibited competitively the shape change caused by 5-HT. 3. The velocity of change in shape caused by 5-HT was reduced in low Na media. 4. Ten analogues produced platelet aggregation; three of these, viz. 5-methoxy-α-methyltryptamine, 5-hydroxy-α-methyltryptamine and 5-hydroxy-N'N'-diisopropyltryptamine), were approximately equipotent with 5-HT. Six analogues did not induce platelet aggregation. 5. All the analogues which prevented the initial change in shape of platelets caused by 5-HT also inhibited its aggregating effect, apparently competitively with low Ki values (0.02-1.6 μM). 6. As with the inhibition of shape change, the inhibition of aggregation shows relatively low structural specificity of the receptor site. 7. Methysergide was a potent inhibitor of shape change and aggregation (Ki∼0.03 μM); imipramine was much less inhibitory (Ki∼5-10 μM). 8. Only one analogue (5-hydroxy-α-methyltryptamine) was taken up like 5-HT by platelets. All the other analogues inhibited the uptake of 5-HT by platelets (Ki=0.2-2.7 μM). 9. Methysergide was a weak inhibitor of 5-HT uptake (Ki∼125 μM) whereas imipramine was very effective (Ki∼0.3 μM). 10. Our results show that the initial change in shape of platelets is required for and precedes aggregation. The structural specificity of the platelet receptor concerned with shape change and aggregation caused by 5-HT appears low whereas the uptake mechanism is a highly specific one. The uptake probably proceeds through more than one step, the

  3. Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney

    PubMed Central

    Gironacci, M. M.

    2016-01-01

    Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na+, K+-ATPase inhibition. Present results show that CNP did not affect either 3H-dopamine uptake in renal tissue or Na+, K+-ATPase activity; meanwhile, Ang-(1-7) was able to increase 3H-dopamine uptake and decreased Na+, K+-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na+, K+-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on 3H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on 3H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on 3H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na+, K+-ATPase activity inhibition, contributing to its natriuretic and diuretic effects.

  4. Integration of Peptides for Enhanced Uptake of PEGylayed Gold Nanoparticles.

    PubMed

    Cruje, C; Chithrani, B D

    2015-03-01

    Polyethylene glycol (PEG) has promoted the prospective applications of nanoparticles (NPs) in cancer therapy. PEG is used to evade the immune system allowing NPs accumulation within the tumor using its leaky vasculature. However, the cellular uptake of PEG-coated (PEGylated) NPs is lower in comparison to non-PEGylated NPs since PEG minimizes surface binding of ligands that mediate NP endocytosis. For improved outcome in therapeutic applications, it is necessary to enhance the uptake of PEGylated NPs. We added a peptide containing an integrin binding domain known as the RGD sequence to the NP surface in addition to PEG. We used gold NPs (GNPs) of sizes 14, 50, and 70 nm in this study. Our in vitro data for HeLa cells show enhanced uptake for NPs coated with both PEG and the peptide in comparison to PEGylated GNPs. NPs of size 50 nm had the highest uptake among the three sizes for all GNP surfaces. A similar size-dependent trend was observed for MDA-MB-231 cells for as-made GNPs with lower uptake in comparison to HeLa cells. However, only 14 nm peptide-modified PEGylated NPs had enhanced uptake. Hence, NP uptake was found dependent on cell type and NP surface properties. A properly designed NP system with both PEG and cell membrane targeting peptides can be used to protect it from the immune system and promote internalization by cells upon entry into tumor environment.

  5. Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney

    PubMed Central

    Gironacci, M. M.

    2016-01-01

    Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na+, K+-ATPase inhibition. Present results show that CNP did not affect either 3H-dopamine uptake in renal tissue or Na+, K+-ATPase activity; meanwhile, Ang-(1-7) was able to increase 3H-dopamine uptake and decreased Na+, K+-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na+, K+-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on 3H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on 3H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on 3H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na+, K+-ATPase activity inhibition, contributing to its natriuretic and diuretic effects. PMID:27635280

  6. Glucose uptake in Oesophagostomum dentatum and the effect of oxfendazole.

    PubMed

    Petersen, M B; Friis, C

    1998-12-31

    The uptake of 14C-glucose by adult Oesophagostomum dentatum was characterised. The uptake was a non-linear function of external glucose concentration. The maximum velocity of uptake (Vmax) was 0.964 nmol/100 mg dry weight (dw)/5 min, and the transport constant (Kt) was 10.02 microM. When phlorizin, phloretin and 3-O-methylglucose were tested for their effects on the uptake of 14C-glucose, phloretin and 3-O-methylglucose produced significant inhibitions, indicating that the uptake was mediated and occurred by facilitated diffusion. Exposure of the worms to oxfendazole prior to incubation with 14C-glucose did not affect the uptake of glucose. In another experiment worms were incubated with unlabelled glucose and the external glucose concentration was measured enzymatically. During a 7 h incubation period, the quantity of glucose remaining in the incubation medium of oxfendazole exposed worms was significantly greater than in the control group. It was concluded that oxfendazole did not influence the process of 14C-glucose uptake, but might induce changes in the parasite leading to a reduced ability to deplete the incubation medium of glucose.

  7. An observing system simulation for Southern Ocean carbon dioxide uptake.

    PubMed

    Majkut, Joseph D; Carter, Brendan R; Frölicher, Thomas L; Dufour, Carolina O; Rodgers, Keith B; Sarmiento, Jorge L

    2014-07-13

    The Southern Ocean is critically important to the oceanic uptake of anthropogenic CO2. Up to half of the excess CO2 currently in the ocean entered through the Southern Ocean. That uptake helps to maintain the global carbon balance and buffers transient climate change from fossil fuel emissions. However, the future evolution of the uptake is uncertain, because our understanding of the dynamics that govern the Southern Ocean CO2 uptake is incomplete. Sparse observations and incomplete model formulations limit our ability to constrain the monthly and annual uptake, interannual variability and long-term trends. Float-based sampling of ocean biogeochemistry provides an opportunity for transforming our understanding of the Southern Ocean CO2 flux. In this work, we review current estimates of the CO2 uptake in the Southern Ocean and projections of its response to climate change. We then show, via an observational system simulation experiment, that float-based sampling provides a significant opportunity for measuring the mean fluxes and monitoring the mean uptake over decadal scales.

  8. Mitochondrial Ca(2+) uptake in skeletal muscle health and disease.

    PubMed

    Zhou, Jingsong; Dhakal, Kamal; Yi, Jianxun

    2016-08-01

    Muscle uses Ca(2+) as a messenger to control contraction and relies on ATP to maintain the intracellular Ca(2+) homeostasis. Mitochondria are the major sub-cellular organelle of ATP production. With a negative inner membrane potential, mitochondria take up Ca(2+) from their surroundings, a process called mitochondrial Ca(2+) uptake. Under physiological conditions, Ca(2+) uptake into mitochondria promotes ATP production. Excessive uptake causes mitochondrial Ca(2+) overload, which activates downstream adverse responses leading to cell dysfunction. Moreover, mitochondrial Ca(2+) uptake could shape spatio-temporal patterns of intracellular Ca(2+) signaling. Malfunction of mitochondrial Ca(2+) uptake is implicated in muscle degeneration. Unlike non-excitable cells, mitochondria in muscle cells experience dramatic changes of intracellular Ca(2+) levels. Besides the sudden elevation of Ca(2+) level induced by action potentials, Ca(2+) transients in muscle cells can be as short as a few milliseconds during a single twitch or as long as minutes during tetanic contraction, which raises the question whether mitochondrial Ca(2+) uptake is fast and big enough to shape intracellular Ca(2+) signaling during excitation-contraction coupling and creates technical challenges for quantification of the dynamic changes of Ca(2+) inside mitochondria. This review focuses on characterization of mitochondrial Ca(2+) uptake in skeletal muscle and its role in muscle physiology and diseases. PMID:27430885

  9. Uptake Mechanism for Iodine Species to Black Carbon

    SciTech Connect

    Choung, Sungwook; Um, Wooyong; Kim, Min Kyung; Kim, Min-Gyu

    2013-08-13

    Natural organic matter (NOM) plays an important role in determining the fate and transport of iodine species such as iodide (I-) and iodate (IO3-) in groundwater system. Although NOM exists as diverse forms in environments, prior iodine studies have mainly focused on uptake processes of iodide and iodate to humic materials. This study was conducted to determine the iodide and iodate uptake potential for a particulate NOM (i.e., black carbon [BC]). A laboratory-produced BC and commercial humic acid were used for batch experiments to compare their iodine uptake properties. The BC exhibited >100 times greater uptake capability for iodide than iodate at low pH~3, while iodide uptake was negligible for the humic acid. The uptake properties of both solids strongly depend on the initial iodine aqueous concentrations. After uptake reaction of iodide to the BC, X-ray Absorption Fine Structure spectroscopy results indicated that the iodide was converted to electrophilic species, and iodine was covalently bound to carbon atom in polycyclic aromatic hydrocarbons present in the BC. The computed distribution coefficients (i.e., Kd values) suggest that the BC materials retard significantly the transport of iodide at low pH in environmental systems containing even a small amount of BC.

  10. Uptake mechanism for iodine species to black carbon.

    PubMed

    Choung, Sungwook; Um, Wooyong; Kim, Minkyung; Kim, Min-Gyu

    2013-09-17

    Natural organic matter (NOM) plays an important role in determining the fate and transport of iodine species such as iodide (I(-)) and iodate (IO3(-)) in groundwater system. Although NOM exists as diverse forms in environments, prior iodine studies have mainly focused on uptake processes of iodide and iodate to humic materials. This study was conducted to determine the iodide and iodate uptake potential for a particulate NOM (i.e., black carbon [BC]). A laboratory-produced BC and commercial humic acid were used for batch experiments to compare their iodine uptake properties. The BC exhibited >100 times greater uptake capability for iodide than iodate at low pH of ~3, while iodide uptake was negligible for the humic acid. The uptake properties of both solids strongly depend on the initial iodine aqueous concentrations. After uptake reaction of iodide to the BC, X-ray absorption fine structure spectroscopy results indicated that the iodide was converted to electrophilic species, and iodine was covalently bound to carbon atom in polycyclic aromatic hydrocarbons present in the BC. The computed distribution coefficients (i.e., Kd values) suggest that the BC materials retard significantly the transport of iodide at low pH in environmental systems containing even a small amount of BC.

  11. Uptake and incorporation of iron in sugar beet chloroplasts.

    PubMed

    Solti, Adám; Kovács, Krisztina; Basa, Brigitta; Vértes, Attila; Sárvári, Eva; Fodor, Ferenc

    2012-03-01

    Chloroplasts contain 80-90% of iron taken up by plant cells. Though some iron transport-related envelope proteins were identified recently, the mechanism of iron uptake into chloroplasts remained unresolved. To shed more light on the process of chloroplast iron uptake, trials were performed with isolated intact chloroplasts of sugar beet (Beta vulgaris). Iron uptake was followed by measuring the iron content of chloroplasts in the form of ferrous-bathophenantroline-disulphonate complex after solubilising the chloroplasts in reducing environment. Ferric citrate was preferred to ferrous citrate as substrate for chloroplasts. Strong dependency of ferric citrate uptake on photosynthetic electron transport activity suggests that ferric chelate reductase uses NADPH, and is localised in the inner envelope membrane. The K(m) for iron uptake from ferric-citrate pool was 14.65 ± 3.13 μM Fe((III))-citrate. The relatively fast incorporation of (57)Fe isotope into Fe-S clusters/heme, detected by Mössbauer spectroscopy, showed the efficiency of the biosynthetic machinery of these cofactors in isolated chloroplasts. The negative correlation between the chloroplast iron concentration and the rate of iron uptake refers to a strong feedback regulation of the uptake.

  12. Specificity of Octopine Uptake by Rhizobium and Pseudomonas Strains

    PubMed Central

    Bergeron, Janique; MacLeod, Robert A.; Dion, Patrice

    1990-01-01

    The octopine-utilizing strain Agrobacterium tumefaciens B6S3 and three nonagrobacteria which had the capacity to utilize this opine were compared for octopine uptake. The characteristics of uptake by Rhizobium meliloti A3 and strain B6S3 were similar. In both bacteria, uptake activity was inducible by octopine and by the related opine octopinic acid, and competition assays showed that these two opine substrates were accepted by the same uptake system with an equivalent affinity. Cells of Pseudomonas putida 203 accumulated octopine against a concentration gradient, and this activity was induced specifically by octopine. While strain 203 did not utilize octopinic acid, a spontaneous mutant with a combined capacity for octopine and octopinic acid utilization was obtained. Both opines induced octopine uptake by this mutant, but octopinic acid was not a substrate for the induced system. Thus, the Pseudomonas uptake system exhibited a different specificity for octopine than the corresponding Agrobacterium system. The nonfluorescent pseudomonad GU187j, which utilized the three related opines octopine, octopinic acid, and nopaline, was constitutive for octopine uptake. Strain GU187j possessed a system which accepted these three opines, but not arginine or ornithine, with a similar affinity. PMID:16348194

  13. Kinetic study on urea uptake with chitosan based sorbent materials.

    PubMed

    Xue, Chen; Wilson, Lee D

    2016-01-01

    A one-pot kinetic uptake study of urea in aqueous solution with various chitosan sorbent materials such as pristine chitosan, cross-linked chitosan with glutaraldehyde from low (C-1) to higher (C-2) glutaraldehyde content, and a Cu(II) complex of a glutaraldehyde cross-linked chitosan material (C-3) is reported herein. The kinetic uptake profiles were analyzed by the pseudo-first order (PFO) and pseudo-second-order (PSO) models, respectively. The uptake rate constant of urea and the sorption capacity (qe) of high molecular weight (HMW) chitosan, C-1, C-2, and C-3 were best described by the PFO model. The uptake rate constant of urea with the various sorbents is listed in ascending order: HMW chitosanuptake values obtained independently at equilibrium conditions. Cross-linked chitosan displays relatively rapid urea uptake and greater adsorption capacity when compared with pristine chitosan. The observed trends are in agreement with the greater surface accessibility and pore structure properties of cross-linked chitosan based on scanning electron microscopy studies. These results further illustrate the rational design of chitosan-based materials for the controlled uptake of urea in aquatic environments.

  14. Uptake of 2, 4-Dichlorophenoxyacetic acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, G.A.

    1966-01-01

    WEDEMEYER, GARY (Fish-Pesticide Research Laboratory, Denver, Colo.). Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens. Appl. Microbiol. 14:486-491. 1966.-Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “nonmetabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carriermediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranylion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  15. Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney.

    PubMed

    Rukavina Mikusic, N L; Kouyoumdzian, N M; Rouvier, E; Gironacci, M M; Toblli, J E; Fernández, B E; Choi, M R

    2016-01-01

    Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na(+), K(+)-ATPase inhibition. Present results show that CNP did not affect either (3)H-dopamine uptake in renal tissue or Na(+), K(+)-ATPase activity; meanwhile, Ang-(1-7) was able to increase (3)H-dopamine uptake and decreased Na(+), K(+)-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na(+), K(+)-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on (3)H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on (3)H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on (3)H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na(+), K(+)-ATPase activity inhibition, contributing to its natriuretic and diuretic effects. PMID:27635280

  16. Use of a chemical equilibrium model to describe surface properties and uptake of cadmium, strontium, and lead by Chlorella (UTEX 252)

    SciTech Connect

    Hassett, J.M.

    1988-01-01

    Metal-aquatic biota interactions are important in both natural and engineered systems. In this study, the uptake of cadmium, strontium and lead by the unicellular green alga Chlorella (UTEX 252) was investigated. Variables included metal concentration, pH, and ionic strength. Data gathered included dry weights (mg/l), cell counts (cells/ml), electrophoretic mobilities (EPMs, {mu}m/sec/V/cm) of metal-free and metal-exposed cells, and metal uptake - difference in concentration in filtrate of cell-metal and cell-free metal solutions. Derived data included cell volumes and surface area, uptake on a {mu}M/m{sup 2} basis, {zeta}-potentials, diffuse layer potentials and charge densities. Typical uptake values were 1.1, 5.2, and 6 {mu}M/m{sup 2} for Cd, Pb, and Sr, respectively, from solutions of pH 6, ionic strength 0.02M, and metal concentration 10{sup {minus}4} M. Cell EPMs were insensitive to metal; under certain conditions, however, (pM > 4, pH > 8), cadmium exposed cells exhibited a reversal in surface charge from negative to positive. The chemical equilibrium model MINEQL1 + STANFORD was used to model algal surface properties and metal uptake. Input data included site pK, density, and {Delta}pK, estimated from EPM-pH data. The model described surface properties of Chlorella (UTEX 252) as judged by a close fit of {zeta}-potentials and model-derived diffuse layer potentials. Metal uptake was modelled by adjusting site density and/or metal-surface site equilibrium constants. Attempts to model surface properties and metal uptake simultaneously were not successful.

  17. Compensatory Root Water Uptake of Overlapping Root Systems

    NASA Astrophysics Data System (ADS)

    Agee, E.; Ivanov, V. Y.; He, L.; Bisht, G.; Shahbaz, P.; Fatichi, S.; Gough, C. M.; Couvreur, V.; Matheny, A. M.; Bohrer, G.

    2015-12-01

    Land-surface models use simplified representations of root water uptake based on biomass distributions and empirical functions that constrain water uptake during unfavorable soil moisture conditions. These models fail to capture the observed hydraulic plasticity that allows plants to regulate root hydraulic conductivity and zones of active uptake based on local gradients. Recent developments in root water uptake modeling have sought to increase its mechanistic representation by bridging the gap between physically based microscopic models and computationally feasible macroscopic approaches. It remains to be demonstrated whether bulk parameterization of microscale characteristics (e.g., root system morphology and root conductivity) can improve process representation at the ecosystem scale. We employ the Couvreur method of microscopic uptake to yield macroscopic representation in a coupled soil-root model. Using a modified version of the PFLOTRAN model, which represents the 3-D physics of variably saturated soil, we model a one-hectare temperate forest stand under natural and synthetic climatic forcing. Our results show that as shallow soil layers dry, uptake at the tree and stand level shift to deeper soil layers, allowing the transpiration stream demanded by the atmosphere. We assess the potential capacity of the model to capture compensatory root water uptake. Further, the hydraulic plasticity of the root system is demonstrated by the quick response of uptake to rainfall pulses. These initial results indicate a promising direction for land surface models in which significant three-dimensional information from large root systems can be feasibly integrated into the forest scale simulations of root water uptake.

  18. Norepinephrine uptake by rat jejunum: Modulation by angiotensin II

    SciTech Connect

    Suvannapura, A.; Levens, N.R. )

    1988-02-01

    Angiotensin II (ANG II) is believed to stimulate sodium and water absorption from the small intestine by enhancing sympathetic nerve transmission. This study is designed to determine whether ANG II can enhance sympathetic neurotransmission within the small intestine by inhibition norepinephrine (NE) uptake. Intracellular NE accumulation by rat jejunum was concentration dependent and resolved into high- and low-affinity components. The high-affinity component (uptake 1) exhibited a Michaelis constant (K{sub m}) of 1.72 {mu}M and a maximum velocity (V{sub max}) of 1.19 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. The low-affinity component (uptake 2) exhibited a K{sub m} of 111.1 {mu}M and a V{sub max} of 37.1 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. Cocaine, an inhibitor of neuronal uptake, inhibited the intracellular accumulation of label by 80%. Treatment of animals with 6-hydroxydopamine, which depletes norepinephrine from sympathetic terminals, also attenuated NE uptake by 60%. Thus accumulation within sympathetic nerves constitutes the major form of ({sup 3}H)NE uptake into rat jejunum. ANG II inhibited intracellular ({sup 3}H)NE uptake in a concentration-dependent manner. At a dose of 1 mM, ANG II inhibited intracellular ({sup 3}H)NE accumulation by 60%. Cocaine failed to potentiate the inhibition of ({sup 3}H)NE uptake produced by ANG II. Thus ANG II appears to prevent ({sup 3}H)NE accumulation within rat jejunum by inhibiting neuronal uptake.

  19. Rain events decrease boreal peatland net CO2 uptake through reduced light availability.

    PubMed

    Nijp, Jelmer J; Limpens, Juul; Metselaar, Klaas; Peichl, Matthias; Nilsson, Mats B; van der Zee, Sjoerd E A T M; Berendse, Frank

    2015-06-01

    Boreal peatlands store large amounts of carbon, reflecting their important role in the global carbon cycle. The short-term exchange and the long-term storage of atmospheric carbon dioxide (CO2 ) in these ecosystems are closely associated with the permanently wet surface conditions and are susceptible to drought. Especially, the single most important peat forming plant genus, Sphagnum, depends heavily on surface wetness for its primary production. Changes in rainfall patterns are expected to affect surface wetness, but how this transient rewetting affects net ecosystem exchange of CO2 (NEE) remains unknown. This study explores how the timing and characteristics of rain events during photosynthetic active periods, that is daytime, affect peatland NEE and whether rain event associated changes in environmental conditions modify this response (e.g. water table, radiation, vapour pressure deficit, temperature). We analysed an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a boreal peatland in northern Sweden. Our results show that daytime rain events systematically decreased the sink strength of peatlands for atmospheric CO2 . The decrease was best explained by rain associated reduction in light, rather than by rain characteristics or drought length. An average daytime growing season rain event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m(-2) . On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that reduced light availability associated with rain events is more important in explaining the NEE response to rain events than rain characteristics and changes in water availability. This suggests that peatland CO2 uptake is highly sensitive to changes in cloud cover formation and to altered rainfall regimes, a process hitherto largely

  20. Rain events decrease boreal peatland net CO2 uptake through reduced light availability.

    PubMed

    Nijp, Jelmer J; Limpens, Juul; Metselaar, Klaas; Peichl, Matthias; Nilsson, Mats B; van der Zee, Sjoerd E A T M; Berendse, Frank

    2015-06-01

    Boreal peatlands store large amounts of carbon, reflecting their important role in the global carbon cycle. The short-term exchange and the long-term storage of atmospheric carbon dioxide (CO2 ) in these ecosystems are closely associated with the permanently wet surface conditions and are susceptible to drought. Especially, the single most important peat forming plant genus, Sphagnum, depends heavily on surface wetness for its primary production. Changes in rainfall patterns are expected to affect surface wetness, but how this transient rewetting affects net ecosystem exchange of CO2 (NEE) remains unknown. This study explores how the timing and characteristics of rain events during photosynthetic active periods, that is daytime, affect peatland NEE and whether rain event associated changes in environmental conditions modify this response (e.g. water table, radiation, vapour pressure deficit, temperature). We analysed an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a boreal peatland in northern Sweden. Our results show that daytime rain events systematically decreased the sink strength of peatlands for atmospheric CO2 . The decrease was best explained by rain associated reduction in light, rather than by rain characteristics or drought length. An average daytime growing season rain event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m(-2) . On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that reduced light availability associated with rain events is more important in explaining the NEE response to rain events than rain characteristics and changes in water availability. This suggests that peatland CO2 uptake is highly sensitive to changes in cloud cover formation and to altered rainfall regimes, a process hitherto largely

  1. Consequences of phosphate application on glyphosate uptake by roots: Impacts for environmental management practices.

    PubMed

    Gomes, Marcelo Pedrosa; Maccario, Sophie; Lucotte, Marc; Labrecque, Michel; Juneau, Philippe

    2015-12-15

    Phosphate (PO4(3-)) fertilization is a common practice in agricultural fields also targets for glyphosate application. Due to their chemical similarities, PO4(3-) and glyphosate compete for soil adsorbing sites, with PO4(3-) fertilization increasing glyphosate bioavailability in the soil solution. After PO4(3-) fertilization, its concentration will be elevated in the soil solution and both PO4(3-) and glyphosate will be readily available for runoff into aquatic ecosystems. In this context, man-made riparian buffer strips (RBS) at the interface of agricultural lands and waterways can be used as a green technology to mitigate water contamination. The plants used in RBS form a barrier to agricultural wastes that can limit runoff, and the ability of these plants to take up these compounds through their roots plays an important role in RBS efficacy. However, the implications of PO4(3-) for glyphosate uptake by roots are not yet clearly demonstrated. Here, we addressed this problem by hydroponically cultivating willow plants in nutrient solutions amended with glyphosate and different concentrations of PO4(3-), assuring full availability of both chemicals to the roots. Using a phosphate carrier inhibitor (phosphonophormic acid-PFA), we found that part of the glyphosate uptake is mediated by PO4(3-) transporters. We observed, however, that PO4(3-) increased glyphosate uptake by roots, an effect that was related to increased root cell membrane stability. Our results indicate that PO4(3-) has an important role in glyphosate physiological effects. Under agricultural conditions, PO4(3-) fertilization can amplify glyphosate efficiency by increasing its uptake by the roots of undesired plants. On the other hand, since simultaneous phosphate and glyphosate runoffs are common, non-target species found near agricultural fields can be affected. PMID:26282745

  2. Consequences of phosphate application on glyphosate uptake by roots: Impacts for environmental management practices.

    PubMed

    Gomes, Marcelo Pedrosa; Maccario, Sophie; Lucotte, Marc; Labrecque, Michel; Juneau, Philippe

    2015-12-15

    Phosphate (PO4(3-)) fertilization is a common practice in agricultural fields also targets for glyphosate application. Due to their chemical similarities, PO4(3-) and glyphosate compete for soil adsorbing sites, with PO4(3-) fertilization increasing glyphosate bioavailability in the soil solution. After PO4(3-) fertilization, its concentration will be elevated in the soil solution and both PO4(3-) and glyphosate will be readily available for runoff into aquatic ecosystems. In this context, man-made riparian buffer strips (RBS) at the interface of agricultural lands and waterways can be used as a green technology to mitigate water contamination. The plants used in RBS form a barrier to agricultural wastes that can limit runoff, and the ability of these plants to take up these compounds through their roots plays an important role in RBS efficacy. However, the implications of PO4(3-) for glyphosate uptake by roots are not yet clearly demonstrated. Here, we addressed this problem by hydroponically cultivating willow plants in nutrient solutions amended with glyphosate and different concentrations of PO4(3-), assuring full availability of both chemicals to the roots. Using a phosphate carrier inhibitor (phosphonophormic acid-PFA), we found that part of the glyphosate uptake is mediated by PO4(3-) transporters. We observed, however, that PO4(3-) increased glyphosate uptake by roots, an effect that was related to increased root cell membrane stability. Our results indicate that PO4(3-) has an important role in glyphosate physiological effects. Under agricultural conditions, PO4(3-) fertilization can amplify glyphosate efficiency by increasing its uptake by the roots of undesired plants. On the other hand, since simultaneous phosphate and glyphosate runoffs are common, non-target species found near agricultural fields can be affected.

  3. A proteolytic pathway that controls glucose uptake in fat and muscle

    PubMed Central

    Belman, Jonathan P.; Habtemichael, Estifanos N.; Bogan, Jonathan S.

    2013-01-01

    Insulin regulates glucose uptake by controlling the subcellular location of GLUT4 glucose transporters. GLUT4 is sequestered within fat and muscle cells during low-insulin states, and is translocated to the cell surface upon insulin stimulation. The TUG protein is a functional tether that sequesters GLUT4 at the Golgi matrix. To stimulate glucose uptake, insulin triggers TUG endoproteolytic cleavage. Cleavage accounts for a large proportion of the acute effect of insulin to mobilize GLUT4 to the cell surface. During ongoing insulin exposure, endocytosed GLUT4 recycles to the plasma membrane directly from endosomes, and bypasses a TUG-regulated trafficking step. Insulin acts through the TC10α GTPase and its effector protein, PIST, to stimulate TUG cleavage. This action is coordinated with insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases, and with other signals to direct overall GLUT4 targeting. Data support the idea that the N-terminal TUG cleavage product, TUGUL, functions as a novel ubiquitin-like protein modifier to facilitate GLUT4 movement to the cell surface. The C-terminal TUG cleavage product is extracted from the Golgi matrix, which vacates an “anchoring” site to permit subsequent cycles of GLUT4 retention and release. Together, GLUT4 vesicle translocation and TUG cleavage may coordinate glucose uptake with physiologic effects of other proteins present in the GLUT4-containing vesicles, and with potential additional effects of the TUG C-terminal product. Understanding this TUG pathway for GLUT4 retention and release will shed light on the regulation of glucose uptake and the pathogenesis of type 2 diabetes. PMID:24114239

  4. Brain Uptake of Neurotherapeutics after Intranasal versus Intraperitoneal Delivery in Mice

    PubMed Central

    Chauhan, Mihir B.; Chauhan, Neelima B.

    2015-01-01

    There is a growing global prevalence of neurodegenerative diseases such as Alzheimer’s disease and dementia. Current treatment for neurodegenerative diseases is limited due to the blood brain barrier’s ability to restrict the entry of therapeutics to the brain. In that context, direct delivery of drugs from nose to brain has gained emerging interest as an important alternative to oral and parenteral routes of administration. Although there are considerable reports showing promising results after intranasal drug delivery in various disease-models and investigatory human clinical trials, there are very few studies showing a detailed pharmacokinetics with regard to the uptake and retention of intranasally delivered material(s) within specific brain regions, which are critical determining factors for dosing conditions and optimal treatment regimen. This investigation compared a time-dependent brain uptake and resident time of various radiolabeled candidate neurotherapeutics after a single bolus intranasal or intraperitoneal administration in mice. Results indicate that the brain uptake of intranasally delivered therapeutic(s) is > 5 times greater than that after intraperitoneal delivery. The peak uptake and resident time of all intranasally delivered test therapeutics for all brain regions is observed to be between 30min-12h, depending upon the distance of brain region from the site of administration, followed by gradual fading of radioactive counts by 24h post intranasal administration. Current study confirms the usefulness of intranasal administration as a non- invasive and efficient means of delivering therapeutics to the brain to treat neurodegenerative diseases including Alzheimer’s disease. PMID:26366437

  5. A proteolytic pathway that controls glucose uptake in fat and muscle.

    PubMed

    Belman, Jonathan P; Habtemichael, Estifanos N; Bogan, Jonathan S

    2014-03-01

    Insulin regulates glucose uptake by controlling the subcellular location of GLUT4 glucose transporters. GLUT4 is sequestered within fat and muscle cells during low-insulin states, and is translocated to the cell surface upon insulin stimulation. The TUG protein is a functional tether that sequesters GLUT4 at the Golgi matrix. To stimulate glucose uptake, insulin triggers TUG endoproteolytic cleavage. Cleavage accounts for a large proportion of the acute effect of insulin to mobilize GLUT4 to the cell surface. During ongoing insulin exposure, endocytosed GLUT4 recycles to the plasma membrane directly from endosomes, and bypasses a TUG-regulated trafficking step. Insulin acts through the TC10α GTPase and its effector protein, PIST, to stimulate TUG cleavage. This action is coordinated with insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases, and with other signals to direct overall GLUT4 targeting. Data support the idea that the N-terminal TUG cleavage product, TUGUL, functions as a novel ubiquitin-like protein modifier to facilitate GLUT4 movement to the cell surface. The C-terminal TUG cleavage product is extracted from the Golgi matrix, which vacates an "anchoring" site to permit subsequent cycles of GLUT4 retention and release. Together, GLUT4 vesicle translocation and TUG cleavage may coordinate glucose uptake with physiologic effects of other proteins present in the GLUT4-containing vesicles, and with potential additional effects of the TUG C-terminal product. Understanding this TUG pathway for GLUT4 retention and release will shed light on the regulation of glucose uptake and the pathogenesis of type 2 diabetes.

  6. Does elevated CO2 alter silica uptake in trees?

    SciTech Connect

    Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; Finzi, Adrien C.

    2015-01-13

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, longterm free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.

  7. Arsenic and Lead Uptake by Vegetable Crops Grown on an Old Orchard Site Amended with Compost

    PubMed Central

    McBride, Murray B.; Shayler, Hannah A.; Russell-Anelli, Jonathan M.; Spliethoff, Henry M.; Marquez-Bravo, Lydia G.

    2015-01-01

    The potential for lead (Pb) and arsenic (As) transfer into vegetables was studied on old orchard land contaminated by lead arsenate pesticides. Root (carrot), leafy (lettuce), and vegetable fruits (green bean, tomato) were grown on seven “miniplots” with soil concentrations ranging from near background to ≈ 800 and ≈ 200 mg kg−1 of total Pb and As, respectively. Each miniplot was divided into sub-plots and amended with 0% (control), 5% and 10% (by weight) compost and cropped for 3 years. Edible portions of each vegetable were analyzed for total Pb and As to test the effect of organic matter on transfer of these toxic elements into the crop. Vegetable Pb and As concentrations were strongly correlated to soil total Pb and As, respectively, but not to soil organic matter content or compost addition level. For Pb vegetable concentrations, carrot ≥ lettuce > bean > tomato. For As, lettuce > carrot > bean > tomato. A complementary single-year study of lettuce, arugula, spinach, and collards revealed a beneficial effect of compost in reducing both Pb and As concentrations in leafy vegetables. Comparisons of all measured vegetable concentrations to international health-based standards indicate that tomatoes can be grown without exceeding standards even in substantially Pb- and As-contaminated soils, but carrots and leafy greens may exceed standards when grown in soils with more than 100–200 mg kg−1 Pb. Leafy greens may also exceed health-based standards in gardens where soil As is elevated, with arugula having a particularly strong tendency to accumulate As. PMID:26900187

  8. Uptake of arsenic and metals by tadpoles at an historically contaminated Texas site

    USGS Publications Warehouse

    Clark, D.R.; Cantu, R.; Cowman, D.F.; Maxson, D.J.

    1998-01-01

    On 14 May 1994, tadpoles were collected from Lateral Pond and Municipal Lake in Bryan, Texas. These waters are immediately downstream from Finfeather Lake which was directly contaminated during 53 years of industrial production of arsenic (As)-based cotton defoliants. The tadpoles contained elevated levels of arsenic, chromium (Cr) and zinc (Zn). As far as it is known, the mean concentrations of As (6.87 p.p.m. wet weight) and Cr (6.91 p.p.m. wet weight) in cricket frog (Acris crepitans) tadpoles were the highest ever reported in tadpoles. The Zn in the tadpoles exceeded the levels found in sediments by six to 11 times. The concentrations of As, Cr and Zn in Finfeather Lake in 1994 may have been toxic because tadpoles could not be found there. Ranid tadpoles and a newly transformed ranid frog found dead in Lateral Pond and Municipal Lake in 1994 may indicate that the elements reached toxic levels in some individual amphibians. The concentrations of As, Cr and Zn found in the tadpoles in this study might be toxic to predators. Mortality of turtles showing symptoms linked to chronic exposure to As was reported in Finfeather Lake in 1973. Turtles were not reported in Finfeather Lake again until 1996. Observations at Municipal Lake in 1994-1996 showed abundant tadpoles and turtles but no snakes, which also have not been seen at Finfeather Lake. This absence of snakes may indicate that their sensitivity or exposure to the existing contaminants is greater than that of frogs and turtles.

  9. Effects of opiates on synaptosomal calmodulin and calcium uptake

    SciTech Connect

    Hoss, W.; Formaniak, M.

    1983-02-01

    Acute opiate administration in vivo increases the level of cytoplasmic calmodulin in isolated rat brain synaptosomes. These synaptosomes do not, however, display decreased K/sup +/-stimulated /sup 45/Ca uptake in vitro. Opiates affect neither cytoplasmic calmodulin nor Ca uptake after incubation of synaptosomes with the drugs in vitro. In contrast to the interpretation of electrophysiological data, these results suggest that the observed inhibition by opiates of the release of several transmitters may not be mediated by presynaptic opiate receptors that inhibit Ca uptake.

  10. Variable Nanoparticle-Cell Adhesion Strength Regulates Cellular Uptake

    NASA Astrophysics Data System (ADS)

    Yuan, Hongyan; Li, Ju; Bao, Gang; Zhang, Sulin

    2010-09-01

    In receptor-mediated endocytosis, cells exercise biochemical control over the mechanics of adhesion to engulf foreign particles, featuring a variable adhesion strength. Here we present a thermodynamic model with which we elucidate that the variable adhesion strength critically governs the cellular uptake, yielding an uptake phase diagram in the space of ligand density and particle size. We identify from the diagram an endocytosed phase with markedly high uptake, encompassed by a lower and an upper phase boundary that are set, respectively, by the enthalpic and entropic limits of the adhesion strength. The phase diagram may provide useful guidance to the rational design of nanoparticle-based therapeutic and diagnostic agents.

  11. Effect of different biochars on Nitrogen uptake in poplar trees

    NASA Astrophysics Data System (ADS)

    George, Elizabeth; Tonon, Giustino; Scandellari, Francesca

    2014-05-01

    Influence of biochar on soil nitrogen transformation and plant uptake has been reported. This paper presents preliminary results of plant N uptake in poplars by using 15N isotope tracer approach Two types of biochar were applied to two sets of pots containing only sand and each pot received a pre-rooted poplar cutting. Half of the pots were inoculated with commercial mycorrhizal gel and the other half were left without. It is intended to provide information on how biochar, mycorrhiza and root interaction mediate nitrogen uptake and organ allocation.

  12. Characterization of iron uptake from transferrin by murine endothelial cells.

    PubMed

    Hallmann, R; Savigni, D L; Morgan, E H; Baker, E

    2000-01-01

    Iron is required by the brain for normal function, however, the mechanisms by which it crosses the blood-brain barrier (BBB) are poorly understood. The uptake and efflux of transferrin (Tf) and Fe by murine brain-derived (bEND3) and lymph node-derived (m1END1) endothelial cell lines was compared. The effects of iron chelators, metabolic inhibitors and the cellular activators, lipopolysaccharide (LPS) and tumour necrosis factor-alpha (TNF-alpha), on Tf and Fe uptake were investigated. Cells were incubated with 59Fe-125I-Tf; Fe uptake was shown to increase linearly over time for both cell lines, while Tf uptake reached a plateau within 2 h. Both Tf and Fe uptake were saturable. bEND3 cells were shown to have half as many Tf receptors as m1END1 cells, but the mean cycling times of a Tf molecule were the same. Tf and Fe efflux from the cells were measured over time, revealing that after 2 h only 25% of the Tf but 80% of the Fe remained associated with the cells. Of 7 iron chelators, only deferriprone (L1) markedly decreased Tf uptake. However, Fe uptake was reduced by more than 50% by L1, pyridoxal isonicotinoyl hydrazone (PIH) and desferrithiocin (DFT). The cellular activators TNF-alpha or LPS had little effect on Tf turnover, but they accelerated Fe uptake in both endothelial cell types. Phenylarsenoxide (PhAsO) and N-ethyl maleimide (NEM), inhibitors of Tf endocytosis, reduced both Tf and Fe uptake in both cell lines, while bafilomycin A1, an inhibitor of endosomal acidification, reduced Fe uptake but did not affect Tf uptake. The results suggest that Tf and Fe uptake by both bEND3 and m1END1 is via receptor-mediated endocytosis with release of Fe from Tf within the cell and recycling of apo-Tf. On the basis of Tf- and Fe-metabolism both cell lines are similar and therefore well suited for use in in vitro models for Fe transport across the BBB.

  13. Elevated sacroilac joint uptake ratios in systemic lupus erythematosus

    SciTech Connect

    De Smet, A.A.; Mahmood, T.; Robinson, R.G.; Lindsley, H.B.

    1984-08-01

    Sacroiliac joint radiographs and radionuclide sacroiliac joint uptake ratios were obtained on 14 patients with active systemic lupus erythematosus. Elevated joint ratios were found unilaterally in two patients and bilaterally in seven patients when their lupus was active. In patients whose disease became quiescent, the uptake ratios returned to normal. Two patients had persistently elevated ratios with continued clinical and laboratory evidence of active lupus. Mild sacroiliac joint sclerosis and erosions were detected on pelvic radiographs in these same two patients. Elevated quantitative sacroiliac joint uptake ratios may occur as a manifestation of active systemic lupus erythematosus.

  14. Gallium uptake in myositis ossificans. Potential pitfalls in diagnosis

    SciTech Connect

    Salzman, L.; Lee, V.W.; Grant, P.

    1987-04-01

    Seven cases of gallium uptake in myositis ossificans are described. Gallium scans are done frequently in paraplegics, quadriplegics, and comatose patients to look for occult infection. It is important to be aware of possible gallium uptake in myositis ossificans, particularly in the extremities, which is frequent in these patients. Gallium uptake may be present prior to any abnormalities seen on plain films or CT scans. It is important to correlate roentgenograms with abnormal gallium scans, particularly in the extremities, to avoid potential pitfalls in diagnosis and prevent unnecessary antibiotic treatment. A bone scan should be obtained whenever possible, particularly when roentgenograms are negative, to confirm the diagnosis.

  15. Characterization of iron uptake from transferrin by murine endothelial cells.

    PubMed

    Hallmann, R; Savigni, D L; Morgan, E H; Baker, E

    2000-01-01

    Iron is required by the brain for normal function, however, the mechanisms by which it crosses the blood-brain barrier (BBB) are poorly understood. The uptake and efflux of transferrin (Tf) and Fe by murine brain-derived (bEND3) and lymph node-derived (m1END1) endothelial cell lines was compared. The effects of iron chelators, metabolic inhibitors and the cellular activators, lipopolysaccharide (LPS) and tumour necrosis factor-alpha (TNF-alpha), on Tf and Fe uptake were investigated. Cells were incubated with 59Fe-125I-Tf; Fe uptake was shown to increase linearly over time for both cell lines, while Tf uptake reached a plateau within 2 h. Both Tf and Fe uptake were saturable. bEND3 cells were shown to have half as many Tf receptors as m1END1 cells, but the mean cycling times of a Tf molecule were the same. Tf and Fe efflux from the cells were measured over time, revealing that after 2 h only 25% of the Tf but 80% of the Fe remained associated with the cells. Of 7 iron chelators, only deferriprone (L1) markedly decreased Tf uptake. However, Fe uptake was reduced by more than 50% by L1, pyridoxal isonicotinoyl hydrazone (PIH) and desferrithiocin (DFT). The cellular activators TNF-alpha or LPS had little effect on Tf turnover, but they accelerated Fe uptake in both endothelial cell types. Phenylarsenoxide (PhAsO) and N-ethyl maleimide (NEM), inhibitors of Tf endocytosis, reduced both Tf and Fe uptake in both cell lines, while bafilomycin A1, an inhibitor of endosomal acidification, reduced Fe uptake but did not affect Tf uptake. The results suggest that Tf and Fe uptake by both bEND3 and m1END1 is via receptor-mediated endocytosis with release of Fe from Tf within the cell and recycling of apo-Tf. On the basis of Tf- and Fe-metabolism both cell lines are similar and therefore well suited for use in in vitro models for Fe transport across the BBB. PMID:10865941

  16. Dietary uptake of superlipophilic compounds by earthworms (Eisenia andrei).

    PubMed

    Belfroid, A; Meiling, J; Drenth, H J; Hermens, J; Seinen, W; van Gestel, K

    1995-08-01

    The uptake and elimination of three superlipophilic compounds (hexabromobenzene, PCB153, and octachloronaphthalene) after dietary uptake was studied in earthworms (Eisenia andrei). All three compounds were taken up from the food, although they did not significantly accumulate despite their hydrophobicity. Both uptake efficiencies (E) and biomagnification factors (BMF) were low. E varied between 0.70 and 7.5%, while BMF values were all below 0.17. The elimination of the compounds was slow, with elimination rate constants k2 varying between 0.04 and 0.09 day-1. PMID:7498054

  17. ERp57 modulates mitochondrial calcium uptake through the MCU.

    PubMed

    He, Jingquan; Shi, Weikang; Guo, Yu; Chai, Zhen

    2014-06-01

    ERp57 participates in the regulation of calcium homeostasis. Although ERp57 modulates calcium flux across the plasma membrane and the endoplasmic reticulum membrane, its functions on mitochondria are largely unknown. Here, we found that ERp57 can regulate the expression of the mitochondrial calcium uniporter (MCU) and modulate mitochondrial calcium uptake. In ERp57-silenced HeLa cells, MCU was downregulated, and the mitochondrial calcium uptake was inhibited, consistent with the effect of MCU knockdown. When MCU was re-expressed in the ERp57 knockdown cells, mitochondrial calcium uptake was restored. Thus, ERp57 is a potent regulator of mitochondrial calcium homeostasis.

  18. Evolution of plant sucrose uptake transporters.

    PubMed

    Reinders, Anke; Sivitz, Alicia B; Ward, John M

    2012-01-01

    In angiosperms, sucrose uptake transporters (SUTs) have important functions especially in vascular tissue. Here we explore the evolutionary origins of SUTs by analysis of angiosperm SUTs and homologous transporters in a vascular early land plant, Selaginella moellendorffii, and a non-vascular plant, the bryophyte Physcomitrella patens, the charophyte algae Chlorokybus atmosphyticus, several red algae and fission yeast, Schizosaccharomyces pombe. Plant SUTs cluster into three types by phylogenetic analysis. Previous studies using angiosperms had shown that types I and II are localized to the plasma membrane while type III SUTs are associated with vacuolar membrane. SUT homologs were not found in the chlorophyte algae Chlamydomonas reinhardtii and Volvox carterii. However, the characean algae Chlorokybus atmosphyticus contains a SUT homolog (CaSUT1) and phylogenetic analysis indicated that it is basal to all other streptophyte SUTs analyzed. SUTs are present in both red algae and S. pombe but they are less related to plant SUTs than CaSUT1. Both Selaginella and Physcomitrella encode type II and III SUTs suggesting that both plasma membrane and vacuolar sucrose transporter activities were present in early land plants. It is likely that SUT transporters are important for scavenging sucrose from the environment and intracellular compartments in charophyte and non-vascular plants. Type I SUTs were only found in eudicots and we conclude that they evolved from type III SUTs, possibly through loss of a vacuolar targeting sequence. Eudicots utilize type I SUTs for phloem (vascular tissue) loading while monocots use type II SUTs for phloem loading. We show that HvSUT1 from barley, a type II SUT, reverted the growth defect of the Arabidopsis atsuc2 (type I) mutant. This indicates that type I and II SUTs evolved similar (and interchangeable) phloem loading transporter capabilities independently. PMID:22639641

  19. Uptake and Loss of Na+, Rb+, and Cs+ in Relation to an Active Mechanism for Extrusion of Na+ in Scenedesmus 1

    PubMed Central

    Kylin, Anders

    1966-01-01

    The mechanism for extrusion of Na+ from Scenedesmus cells is characterized physiologically. It is stimulated by phosphate but oxygen is not necessary. Rb+ and Cs+ may also be extruded, but in the presence of Na+ they cannot compete for the sites on the inside of the transport system. When Na+ is extruded, Rb+ and, by inference, K+ seems to be transported as counter ion from the outside, and sodium ions compete only weakly for this external site. The parallelism between these findings and the Na+-K+-activated adenosine triphosphatases known from animal tissues is pointed out. With low additions of phosphate, the extrusion mechanism can keep the cells practically free from Na+. Increasing the concentrations of external phosphate stimulates uptake more than extrusion, and a net uptake occurs. As for Rb+ and Cs+, they are taken up in the absence of external phosphate, but additions of P will greatly enhance the amounts absorbed. Two different ways of uptake are indicated. PMID:5932402

  20. Phytochelatin systhesis and cadmium uptake of Brassica napus.

    PubMed

    Selvam, A; Wong, J W C

    2008-07-01

    Soil contamination with cadmium (Cd) poses risk to human health. Metal hyperaccumulator plants play an important role in phytoextraction of heavy metals from such contaminated sites. Accumulation of Cd and its influence on the induction of phytochelatins in Brassica napus was investigated. Brassica napus plants were grown in nutrient culture with 1 and 5 microM Cd for 10 days. The biomass negatively correlates with Cd concentration in the nutrient solution and the reduction in dry weight was significantly higher for the root than the shoot. Cadmium accumulation positively correlates with the Cd concentration in the nutrient solution and the Cd accumulation in root is significantly higher than the shoot. High-performance liquid chromatography (HPLC) analysis revealed the induction of PC2, PC3 and PC4 in response to Cd in B. napus and their concentrations vary with the Cd level in the external solution. In 1 microM Cd treated plants; PC2 was the dominant thiol fraction in the root, followed by PC3 and PC4, whereas in the shoot, PC3 is the dominant species followed by PC4 and PC2. In 5 microM Cd treated plants, the concentration of both PC3 and PC4 are higher than that of PC2 in the roots. In the shoot, the concentration of PC3 and PC4 was higher than the PC2 irrespective of the quantity of Cd uptake, implying that the detoxification of Cd involves higher molecular weight thiol complexes in the shoot. Considering the high aboveground biomass and Cd accumulation in the shoot, B. napus can be a potential candidate for the phytoextraction of Cd. PMID:18697518

  1. Arbuscular mycorrhizal colonization reduces arsenate uptake in barley via downregulation of transporters in the direct epidermal phosphate uptake pathway.

    PubMed

    Christophersen, H M; Smith, F A; Smith, S E

    2009-12-01

    *Here, we used barley (Hordeum vulgare) grown in normal and compartmented pots to investigate sensitivity to arsenic (As) in the absence of a positive growth response to arbuscular mycorrhizas (AM). *We tested the hypothesis that upon inoculation with AM fungi downregulation of HvPht1;1 and HvPht1;2 genes (encoding high-affinity inorganic orthophosphate (P(i))-uptake systems in a direct pathway via root epidermis and root hairs) and upregulation of the AM-induced HvPht1;8 (encoding the P(i)-uptake system responsible for transfer of P(i) from the symbiotic interface to cortical cells) play a role in decreased As uptake and hence reduced As sensitivity in AM plants. *Barley did not respond, or responded negatively to colonization by Glomus intraradices in terms of growth. In terms of specific phosphorus (P) uptake (P uptake per g of root) barley was nonresponsive. There was a significant interaction between As treatment and colonization, resulting in a lower As concentration and uptake in AM compared with nonmycorrhizal (NM) plants. *The decreased uptake of As and higher P : As molar ratios in the AM barley can be explained by the operation of the AM pathway as indicated by induction of HvPht1;8 and by down-regulation of HvPht1;1 and HvPht1;2.

  2. Kinetics of ClONO(2) reactive uptake on ice surfaces at temperatures of the upper troposphere.

    PubMed

    Fernandez, Miguel A; Hynes, Robert G; Cox, Richard A

    2005-11-10

    The reactive uptake kinetics of ClONO(2) on pure and doped water-ice surfaces have been studied using a coated wall flow tube reactor coupled to an electron impact mass spectrometer. Experiments have been conducted on frozen film ice surfaces in the temperature range 208-228 K with P((ClONO)(2)) < or = 10(-6) Torr. The uptake coefficient (gamma) of ClONO(2) on pure ice was time dependent with a maximum value of gamma(max) approximately 0.1. On HNO(3)-doped ice at 218 K the gamma(max) was 0.02. HOCl formation was detected in both experiments. On HCl-doped ice, uptake was gas-phase diffusion limited (gamma > 0.1) and gas-phase Cl(2) was formed. The uptake of HCl on ice continuously doped with HNO(3) was reversible such that there was no net uptake of HCl once the equilibrium surface coverage was established. The data were well described by a single site 2-species competitive Langmuir adsorption isotherm. The surface coverage of HCl on HNO(3)-doped ice was an order of magnitude lower than on bare ice for a given temperature and P(HCl). ClONO(2) uptake on this HCl/HNO(3)-doped ice was studied as a function of P(HCl). gamma(max) was no longer gas-phase diffusion limited and was found to be linearly dependent on the surface concentration of HCl. Under conditions of low HCl surface concentration, hydrolysis of ClONO(2) and reaction with HCl were competing such that both Cl(2) and HOCl were formed. A numerical model was used to simulate the experimental results and to aid in the parametrization of ClONO(2) reactivity on cirrus ice clouds in the upper troposphere.

  3. Modeling the carbon cost of plant nitrogen acquisition: Mycorrhizal trade-offs and multipath resistance uptake improve predictions of retranslocation

    NASA Astrophysics Data System (ADS)

    Brzostek, Edward R.; Fisher, Joshua B.; Phillips, Richard P.

    2014-08-01

    Accurate projections of the future land carbon (C) sink by terrestrial biosphere models depend on how nutrient constraints on net primary production are represented. While nutrient limitation is nearly universal, current models do not have a C cost for plant nutrient acquisition. Also missing are symbiotic mycorrhizal fungi, which can consume up to 20% of net primary production and supply up to 50% of a plant's nitrogen (N) uptake. Here we integrate simultaneous uptake and mycorrhizae into a cutting-edge plant N model—Fixation and Uptake of Nitrogen (FUN)—that can be coupled into terrestrial biosphere models. The C cost of N acquisition varies as a function of mycorrhizal type, with plants that support arbuscular mycorrhizae benefiting when N is relatively abundant and plants that support ectomycorrhizae benefiting when N is strongly limiting. Across six temperate forested sites (representing arbuscular mycorrhizal- and ectomycorrhizal-dominated stands and 176 site years), including multipath resistance improved the partitioning of N uptake between aboveground and belowground sources. Integrating mycorrhizae led to further improvements in predictions of N uptake from soil (R2 = 0.69 increased to R2 = 0.96) and from senescing leaves (R2 = 0.29 increased to R2 = 0.73) relative to the original model. On average, 5% and 9% of net primary production in arbuscular mycorrhizal- and ectomycorrhizal-dominated forests, respectively, was needed to support mycorrhizal-mediated acquisition of N. To the extent that resource constraints to net primary production are governed by similar trade-offs across all terrestrial ecosystems, integrating these improvements to FUN into terrestrial biosphere models should enhance predictions of the future land C sink.

  4. Decadal predictions of the North Atlantic CO2 uptake.

    PubMed

    Li, Hongmei; Ilyina, Tatiana; Müller, Wolfgang A; Sienz, Frank

    2016-01-01

    As a major CO2 sink, the North Atlantic, especially its subpolar gyre region, is essential for the global carbon cycle. Decadal fluctuations of CO2 uptake in the North Atlantic subpolar gyre region are associated with the evolution of the North Atlantic Oscillation, the Atlantic meridional overturning circulation, ocean mixing and sea surface temperature anomalies. While variations in the physical state of the ocean can be predicted several years in advance by initialization of Earth system models, predictability of CO2 uptake has remained unexplored. Here we investigate the predictability of CO2 uptake variations by initialization of the MPI-ESM decadal prediction system. We find large multi-year variability in oceanic CO2 uptake and demonstrate that its potential predictive skill in the western subpolar gyre region is up to 4-7 years. The predictive skill is mainly maintained in winter and is attributed to the improved physical state of the ocean. PMID:27026490

  5. Significance of diffuse pulmonary uptake in radiogallium scans: concise communication

    SciTech Connect

    Gupta, S.M.; Sziklas, J.J.; Spencer, R.P.; Rosenberg, R.

    1980-04-01

    Diffuse pulmonary uptake of radiogallium was observed in 50 out of 510 scans (9.8%) performed in a general hospital over a period of 1 y. Of the 50 cases, 80% had bilateral, diffuse distribution, and 20% unilateral. A variety of clinical conditions produced a similar picture on the pulmonary images. The most common cause of the diffuse uptake was infectious disease (48%) followed by infiltrative disorders (30%) and neoplastic conditions (22%). On a repeat study there was significant reduction in the intensity of pulmonary radiogallium uptake following drug therapy in three patients - sarcoidosis on corticosteroid therapy, pneumocystis carinii treated with trimethoprim and sulfamethoxozole, and interstitial pulmonary fibrosis on corticosteroids. No close correlation was observed between the underlying clinical disorder and the pattern or intensity of pulmonary uptake of radiogallium.

  6. A peak and decline in North Atlantic CO2 uptake

    NASA Astrophysics Data System (ADS)

    Halloran, Paul; Lebehot, Alice; Watson, Andy; McNeall, Doug; Schuster, Ute; Voelker, Christoph; Booth, Ben; Totterdell, Ian; Jones, Chris; Lambert, Hugo

    2016-04-01

    The oceans play a vital role in mitigating climate change by removing anthropogenic CO2 from the atmosphere. Presently, only around half of human-emitted CO2 remains in the atmosphere, with the rest being taken up by the land and ocean carbon sinks in approximately equal proportions. Of the ocean's CO2 uptake, that occurring in that high-latitude North Atlantic is the most intense. We develop a theoretical framework whic