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Sample records for increases quantal size

  1. Secretory vesicle rebound hyperacidification and increased quantal size due to prolonged methamphetamine exposure

    PubMed Central

    Markov, Dmitriy; Mosharov, Eugene V.; Setlik, Wanda; Gershon, Michael D.; Sulzer, David

    2009-01-01

    Acute exposure to amphetamines collapses secretory vesicle pH gradients, which increases cytosolic catecholamine levels while decreases the quantal size of catecholamine release during fusion events. Amphetamine and methamphetamine, however, are retained in tissues over long durations. We used optical and electron microscopic probes to measure the effects of long-term methamphetamine exposure on secretory vesicle pH, and amperometry and intracellular patch electrochemistry to observe the effects on neurosecretion and cytosolic catecholamines in cultured rat chromaffin cells. In contrast to acute methamphetamine effects, exposure to the drug for 6–48 h at 10 μM and higher concentrations produced a concentration-dependent rebound hyperacidification of secretory vesicles. At 5–10 μM levels, methamphetamine increased the quantal size and reinstated exocytotic catecholamine release, although very high (>100 μM) levels of the drug, while continuing to produce rebound hyperacidification, did not increase quantal size. Secretory vesicle rebound hyperacidification was temperature dependent with optimal response at ~ 37°C, was not blocked by the transcription inhibitor, puromycin, and appears to be a general compensatory response to prolonged exposure with membranophilic weak bases, including amphetamines, methylphenidate, cocaine, and ammonia. Thus, under some conditions of prolonged exposure, amphetamines and other weak bases can enhance, rather than deplete, the vesicular release of catecholamines via a compensatory response resulting in vesicle acidification. PMID:19014382

  2. Calcitonin gene-related peptide increases acetylcholine quantal size in neuromuscular junctions of mice.

    PubMed

    Gaydukov, Alexander E; Bogacheva, Polina O; Balezina, Olga P

    2016-08-15

    We used an intracellular microelectrode technique to study the mechanisms of action of two isoforms (human and rat) of calcitonin gene-related peptide (CGRP) on the evoked and spontaneous quantal secretion of acetylcholine (ACh) in mouse diaphragm motor synapses. Recordings of miniature endplate potentials (MEPPs) and evoked multiquantal endplate potentials (EPPs) in a cut neuromuscular preparation showed that CGRP increased the amplitude of EPPs without influencing their quantal content. Both isoforms of CGRP in a wide range of concentrations (1nM-1μM) provoked a similar considerable increase in MEPPs amplitude in a dose-dependent manner (up to 150-160% compared to control) without changing their frequency, rise-time, and decay. Inhibition of CGRP-receptors by truncated CGRP (CGRP8-37) completely prevented the potentiating effect of CGRP on the MEPPs amplitude. The effect of CGRP was not accompanied by changes in input resistance of muscle fiber membrane but was fully prevented by inhibition of vesicular ACh transport by vesamicol. Inhibition of protein kinase A (PKA) by H-89 also prevented CGRP action on the MEPPs amplitude. It is concluded that, in mammalian neuromuscular junctions, different isoforms of exogenously applied CGRP uniformly potentiate amplitudes of evoked and spontaneous postsynaptic potentials acting presynaptically via an increase in ACh quantal size. PMID:27288020

  3. Presynaptic Molecular Determinants of Quantal Size

    PubMed Central

    Takamori, Shigeo

    2016-01-01

    The quantal hypothesis for the release of neurotransmitters at the chemical synapse has gained wide acceptance since it was first worked out at the motor endplate in frog skeletal muscle in the 1950’s. Considering the morphological identification of synaptic vesicles (SVs) at the nerve terminals that appeared to be homogeneous in size, the hypothesis proposed that signal transduction at synapses is mediated by the release of neurotransmitters packed in SVs that are individually uniform in size; the amount of transmitter in a synaptic vesicle is called a quantum. Although quantal size—the amplitude of the postsynaptic response elicited by the release of neurotransmitters from a single vesicle—clearly depends on the number and sensitivity of the postsynaptic receptors, accumulating evidence has also indicated that the amount of neurotransmitters stored in SVs can be altered by various presynaptic factors. Here, I provide an overview of the concepts and underlying presynaptic molecular underpinnings that may regulate quantal size. PMID:26903855

  4. PDE type-4 inhibition increases L-type Ca(2+) currents, action potential firing, and quantal size of exocytosis in mouse chromaffin cells.

    PubMed

    Marcantoni, A; Carabelli, V; Vandael, D H; Comunanza, V; Carbone, E

    2009-03-01

    We studied the effects of the cAMP-hydrolyzing enzyme phosphodiesterase type-4 (PDE4) on the L-type Ca(2+) channels (LTCCs) and Ca(2+)-dependent secretion in mouse chromaffin cells (MCCs). The selective PDE4 inhibitor rolipram (3 microM) had a specific potentiating action on Ca(2+) currents of MCCs (40% increase within 3 min). A similar effect was produced by the selective beta(1)-AR agonist denopamine (1 microM) and by the unselective PDEs inhibitor IBMX (100 microM). Rolipram and denopamine actions were selective for LTCCs, and the Ca(2+) current increase remained unchanged if the two compounds were applied simultaneously. This suggests that at rest, LTCCs in MCCs are down-regulated by the low levels of cAMP determined by PDE4 activity and that LTCCs can be up-regulated by either inhibiting PDE4 or activating beta(1)-AR. No other PDEs are likely involved in this specific action. PDE4 inhibition had also a marked effect on the spontaneous firing of resting MCCs and catecholamine secretion. Rolipram up-regulated the LTCCs contributing to the "pace-maker" current underlying action potential (AP) discharges and accelerated the firing rate, with no significant effects on AP waveform. Acceleration of AP firing was also induced by the LTCC-agonist Bay K (1 microM), while nifedipine (3 microM) reduced the firing frequency, suggesting that LTCCs and intracellular cAMP play a key role in setting the pace-maker current regulating MCCs excitability. Rolipram increased also the size of the ready-releasable pool and the quantal content of secretory vesicles without affecting their probability of release. Thus, rolipram acts on MCCs by up-regulating both exocytosis and AP firings. These two processes are effectively down-regulated by PDE4 at rest and can dramatically increase the quantity of released catecholamines when PDE4 is inhibited and/or cAMP is raised. PMID:18779976

  5. The active zone protein CAST regulates synaptic vesicle recycling and quantal size in the mouse hippocampus.

    PubMed

    Kobayashi, Shizuka; Hida, Yamato; Ishizaki, Hiroyoshi; Inoue, Eiji; Tanaka-Okamoto, Miki; Yamasaki, Miwako; Miyazaki, Taisuke; Fukaya, Masahiro; Kitajima, Isao; Takai, Yoshimi; Watanabe, Masahiko; Ohtsuka, Toshihisa; Manabe, Toshiya

    2016-09-01

    Synaptic efficacy is determined by various factors, including the quantal size, which is dependent on the amount of neurotransmitters in synaptic vesicles at the presynaptic terminal. It is essential for stable synaptic transmission that the quantal size is kept within a constant range and that synaptic efficacy during and after repetitive synaptic activation is maintained by replenishing release sites with synaptic vesicles. However, the mechanisms for these fundamental properties have still been undetermined. We found that the active zone protein CAST (cytomatrix at the active zone structural protein) played pivotal roles in both presynaptic regulation of quantal size and recycling of endocytosed synaptic vesicles. In the CA1 region of hippocampal slices of the CAST knockout mice, miniature excitatory synaptic responses were increased in size, and synaptic depression after prolonged synaptic activation was larger, which was attributable to selective impairment of synaptic vesicle trafficking via the endosome in the presynaptic terminal likely mediated by Rab6. Therefore, CAST serves as a key molecule that regulates dynamics and neurotransmitter contents of synaptic vesicles in the excitatory presynaptic terminal in the central nervous system. PMID:27422015

  6. Analysis of quantal size of voltage responses to retinal stimulation in the accessory optic system.

    PubMed

    Ariel, Michael; Johny, Manu Ben

    2007-07-01

    In the intact vertebrate central nervous system, the quantal nature of synaptic transmission is difficult to measure because the postsynaptic sites may be distributed along a tortuous dendritic tree that cannot be readily clamped spatially to a uniform potential. Titrating the intact brain's extracellular concentration of calcium ions is also challenging because of its strong buffering mechanisms. In this study, using a whole brain with eye attached preparation, quantal neurotransmission was examined in the turtle brainstem in vitro, by recording from accessory optic system neurons that receive direct input from visually responsive retinal ganglion cells. Unitary EPSPs, evoked by microstimulation of a single ganglion cell, were measured during whole cell current-clamp recordings. In this preparation, the neurons exhibit direction-selectivity, despite the hypoxic conditions. Bath application of cadmium to reduce calcium influx also reduced evoked EPSP amplitudes to that of the spontaneous synaptic events. Statistical analyses indicated that these evoked response amplitudes could be well fitted to a Poisson distribution for most brainstem neurons. Therefore, the spontaneous miniature excitatory synaptic events of approximately 1 mV, as also observed during spike blockade of the retina [Kogo, N., Ariel, M., 1997. Membrane properties and monosynaptic retinal excitation of neurons in the turtle accessory optic system. Journal of Neurophysiology 78, 614-627], are likely responses to the neurotransmitter of single vesicles release by retinal axon terminals. PMID:17543898

  7. Quantal currents evoked by graded intracellular depolarization of crayfish motor axon terminals.

    PubMed Central

    Atwood, H L; Parnas, H; Parnas, I; Wojtowicz, J M

    1987-01-01

    1. Quantal transmitter release was examined at nerve terminals of the excitatory motor axon of the crayfish opener muscle. The magnitude of synaptic currents, recorded with macro-patch electrodes at a nerve terminal, served as a measure of quantal size. Transmitter release was initiated by pulses of depolarizing current applied intracellularly to the axonal terminals after application of tetrodotoxin. Quantal release was altered by a variety of methods and the resulting quantal output and quantal size were measured. 2. Amplitude distributions of quantal events were obtained during experimental manipulations which altered the rate of quantal release by up to 25-fold. These manipulations consisted of: varying pulse amplitude or pulse duration; facilitating the release by prolonged depolarization; and application of a potassium channel blocker, 4-aminopyridine. 3. The amplitude of quantal events is impervious to marked changes in presynaptic depolarization and is not affected by experimental procedures which promote accumulation of calcium ions in the terminals. The vesicular mechanism of release, in which transmitter substance is prepackaged in vesicles which individually undergo exocytosis at a release zone, could account for the observed results. PMID:2888878

  8. Adaptation of quantal content to decreased postsynaptic sensitivity at single endplates in alpha-bungarotoxin-treated rats.

    PubMed Central

    Plomp, J J; van Kempen, G T; Molenaar, P C

    1992-01-01

    1. Rats were injected once every 48 h with alpha-bungarotoxin (alpha BTX) for periods up to 6 weeks. Injections caused weakness of facial muscles which lasted about 8 h. Hemidiaphragms were dissected for biochemical and electrophysiological measurements. 2. In muscles from animals treated for 2-3 weeks with toxin, the binding of 125I-alpha BTX was reduced to 58%, and the ACh content to 81% of control values. Choline acetyltransferase activity was unchanged. ACh release evoked by 3 Hz nerve stimulation was increased to 175% of control values. 3. The use of mu-conotoxin, which specifically blocks muscle action potentials, enabled the recording of full-sized endplate potentials (EPPs) and miniature endplate potentials (MEPPs) at normal muscle membrane potentials (-70 to -80 mV). The amplitude of MEPPs was decreased to 57% in muscles from animals treated for 3 weeks with alpha BTX. The mean of the quantal contents, calculated from the ratio of the corrected EPPs and the MEPPs, was increased to 154%. 4. Within individual muscles of both alpha BTX-treated and control rats, there was an inverse relationship between the quantal content of an endplate and its MEPP amplitude. 5. The MEPP frequency of endplates from control muscles was positively correlated with the quantal content. However, this correlation was not found in alpha BTX-affected muscles. 6. Three hours after a single injection of alpha BTX the amplitude of the MEPPs was reduced to about 60% of control values but no increase of the quantal content was found. During the first few days of alpha BTX treatment the quantal content gradually increased; it reached a plateau between 20 and 30 days. 7. The results suggest the existence of an adaptive mechanism, operating at individual endplates, in which retrograde signals at the motor nerve terminals modulate ACh release when neuromuscular transmission is endangered by block of acetylcholine receptors. PMID:1302275

  9. TOTAL CULTURABLE VIRUS QUANTAL ASSAY

    EPA Science Inventory

    This chapter describes a quantal method for assaying culturable human enteric viruses from water matrices. The assay differs from the plaque assay described in Chapter 10 (December 1987 Revision) in that it is based upon the direct microscopic viewing of cells for virus-induced ...

  10. Facilitation at single synapses probed with optical quantal analysis.

    PubMed

    Oertner, Thomas G; Sabatini, Bernardo L; Nimchinsky, Esther A; Svoboda, Karel

    2002-07-01

    Many synapses can change their strength rapidly in a use-dependent manner, but the mechanisms of such short-term plasticity remain unknown. To understand these mechanisms, measurements of neurotransmitter release at single synapses are required. We probed transmitter release by imaging transient increases in [Ca(2+)] mediated by synaptic N-methyl-D-aspartate receptors (NMDARs) in individual dendritic spines of CA1 pyramidal neurons in rat brain slices, enabling quantal analysis at single synapses. We found that changes in release probability, produced by paired-pulse facilitation (PPF) or by manipulation of presynaptic adenosine receptors, were associated with changes in glutamate concentration in the synaptic cleft, indicating that single synapses can release a variable amount of glutamate per action potential. The relationship between release probability and response size is consistent with a binomial model of vesicle release with several (>5) independent release sites per active zone, suggesting that multivesicular release contributes to facilitation at these synapses. PMID:12055631

  11. Quantal Cumulant Dynamics for Dissipative Systems

    SciTech Connect

    Shigeta, Yasuteru

    2007-12-26

    We develop a quantal cumulant dynamics method for the quantum tunneling in dissipative environment. Reduced equations of motion of classical and quantal cumulant variables without bath degrees of freedom are derived. We observed suppression of the tunneling that depends on the sign of a friction constant for an Ohmic approximation and on the magnitude of a bath frequency for a single bath mode approximation. A possible mechanism of the suppression is explored by analyzing an effective quantal potential of the tunneling path.

  12. Quantal Heating of Conducting Electrons with Discrete Spectrum

    SciTech Connect

    Vitkalov, S. A.; Bykov, A. A.

    2011-12-23

    Usually heating of conducting electrons by dc electric field results in an increase of electron temperature. In this paper we show that the dc heating of 2D electrons, placed in quantized magnetic fields, results in a peculiar electron distribution, which has the same broadening or an effective 'temperature' as the unbiased electron system. The quantal heating, however, violates strongly the Ohm's Law. In the conducting system with discrete electron spectrum the quantal heating results in spectacular decrease of electron resistance and transition of the electrons into a state with zero differential resistance (ZDR). Finally the heating leads to apparent dc driven metal-insulator transition, which correlates with the transition into the ZDR state. The correlation is very unexpected and is not understood.

  13. Dose-response model for teratological experiments involving quantal responses

    SciTech Connect

    Rai, K.; Van Ryzin, J.

    1985-03-01

    This paper introduces a dose-response model for teratological quantal response data where the probability of response for an offspring from a female at a given dose varies with the litter size. The maximum likelihood estimators for the parameters of the model are given as the solution of a nonlinear iterative algorithm. Two methods of low-dose extrapolation are presented, one based on the litter size distribution and the other a conservative method. The resulting procedures are then applied to a teratological data set from the literature.

  14. The effect of opiates on the terminal nerve impulse and quantal secretion from visualized amphibian nerve terminals.

    PubMed Central

    Lavidis, N. A.

    1995-01-01

    1. Secretion of transmitter from amphibian motor nerve terminal release sites is intermittent, spatially non-uniform and varies considerably throughout the year and during development. The role of opioid receptors in modulating transmitter secretion from amphibian motor nerve terminals is evaluated in this study. 2. Dynorphin-A (24 microM) and morphine (500 microM) did not significantly change the shape of the nerve impulse or the consistency with which it was observed, but decreased evoked quantal secretion by more than 50%. These effects of dynorphin-A and morphine were largely reversed by naloxone (50 microM). 3. Dynorphin-A and morphine did not significantly change either the amplitude or the frequency of spontaneous quantal secretions. 4. There was a uniform decrease in evoked quantal secretion from release sites along terminal branches, irrespective of the quantal content value before drug treatment, indicating no difference in the susceptibility of proximal vs distal release sites to opiates. 5. Increasing the extracellular calcium concentration (0.3 to 0.4 mM) or trains of conditioning-test impulses (25 to 100 Hz) resulted in smaller dynorphin-A or morphine-induced decreases in evoked quantal secretion. 6. The decrease in evoked quantal secretion occurs as a result of a uniform decrease in the probability of quantal secretion from release sites without any affect on the propagation of the nerve terminal impulse. Low probability release sites become effectively silent. PMID:7582455

  15. Increasing the Size of Microwave Popcorn

    NASA Astrophysics Data System (ADS)

    Smoyer, Justin

    2005-03-01

    Each year Americans consume approximately 17 billion quarts of popcorn. Since the 1940s, microwaves have been the heating source of choice for most. By treating the popcorn mechanism as a thermodynamic system, it has been shown mathematically and experimentally that reducing the surrounding pressure of the unpopped kernels, results in an increased volume of the kernels [Quinn et al, http://xxx.lanl.gov/abs/cond-mat/0409434 v1 2004]. In this project an alternate method of popping with the microwave was used to further test and confirm this hypothesis. Numerous experimental trials where run to test the validity of the theory. The results show that there is a significant increase in the average kernel size as well as a reduction in the number of unpopped kernels.

  16. Quantal analysis of excitatory synapses in rat hippocampal CA1 in vitro during low-frequency depression.

    PubMed Central

    Larkman, A U; Jack, J J; Stratford, K J

    1997-01-01

    1. We have performed a detailed quantal analysis of excitatory postsynaptic potentials (EPSPs) evoked by minimal extracellular stimulation in the CA1 region of slices of adult rat hippocampus maintained in vitro. 2. EPSPs were evoked at 2-5 Hz, and the eight that were analysed all showed at least a 50% depression of mean peak amplitude during recording. 3. EPSP amplitude fluctuations were analysed by three methods: the use of amplitude frequency histograms with clear and reliable peaks where available, graphs of the EPSP (coefficient of variation)-2 against EPSP mean, and analysis of EPSP mean and standard deviation assuming simple binomial statistics with the number of release sites (N) kept constant but the quantal size (Q) and the release probability (Pr) allowed to vary over time. 4. The results of the three analysis procedures were in good agreement. Seven EPSPs showed a substantial reduction in the mean number of quanta released per trial, and in three cases this was the predominant mechanism of the depression. Five EPSPs showed a substantial decrease in Q. Values for N ranged between 3 and 18, with a median of 6; Pr ranged between 0.14 and 0.81 and Q between 66 and 275 microV. 5. We used the Q estimates from the binomial method to correct the recorded EPSP amplitudes for changes in quantal size over time. For seven out of the eight EPSPs, this rescaling procedure allowed histograms with clear peaks to be obtained from longer runs of data, or improved the sharpness of the peaks in histograms from all the recorded data. The improvement in peak sharpness was assessed using an autocorrelation-based method. The correction was much less successful if the Q estimates were obtained with a variant of the binomial method in which Pr was held constant and N was allowed to vary. 6. The only simple explanation for the success of the correction procedure is that changes in quantal size were a major factor in obscuring peaks in histograms based on large numbers of trials

  17. Preferential cell attachment to nitrogen-doped diamond-like carbon (DLC:N) for the measurement of quantal exocytosis

    PubMed Central

    Sen, Atanu; Barizuddin, Syed; Hossain, Maruf; Polo-Parada, Luis; Gillis, Kevin D.; Gangopadhyay, Shubhra

    2013-01-01

    Electrochemical measurement of transmitter or hormone release from individual cells on microchips has applications both in basic science and drug screening. High-resolution measurement of quantal exocytosis requires the working electrode to be small (cell-sized) and located in immediate proximity to the cell. We examined the ability of candidate electrode materials to promote the attachment of two hormone-secreting cell types as a mechanism for targeting cells for to recording electrodes with high precision. We found that nitrogen-doped diamond-like carbon (DLC:N) promoted cell attachment relative to other materials tested in the rank order of DLC:N > In2O3/SnO2 (ITO), Pt > Au. In addition, we found that treating candidate electrode materials with polylysine did not increase attachment of chromaffin cells to DLC:N, but promoted cell attachment to the other tested materials. We found that hormone-secreting cells did not attach readily to Teflon AF as a potential insulating material, and demonstrated that patterning of Teflon AF leads to selective cell targeting to DLC:N “docking sites”. These results will guide the design of the next generation of biochips for automated and high-throughput measurement of quantal exocytosis. PMID:19124153

  18. Reducing Class Size To Increase Student Involvement.

    ERIC Educational Resources Information Center

    Lottes, Christine R.

    Reducing class size was considered an important element in a revised health course at Gettysburg College (Pennsylvania). However, reducing class size to approximately 15 students per class would require 38 sections, more than the health faculty could handle. To recruit additional instructors, the course was marketed to faculty and administrators…

  19. Illustrating Concepts of Quantal Analysis with an Intuitive Classroom Model

    ERIC Educational Resources Information Center

    Xu-Friedman, Matthew A.

    2013-01-01

    The quantal hypothesis is central to the modern understanding of how a neurotransmitter is released from synapses. This hypothesis expresses that a neurotransmitter is packaged together in quanta that are released probabilistically. The experiments that led to the quantal hypothesis are often related in introductory neuroscience textbooks, but…

  20. Slow kinetics of inositol 1,4,5-trisphosphate-induced Ca2+ release: is the release 'quantal' or 'non-quantal'?

    PubMed Central

    Missiaen, L; De Smedt, H; Parys, J B; Sienaert, I; Sipma, H; Vanlingen, S; Casteels, R

    1997-01-01

    Inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ release from intracellular stores is generally assumed to be a 'quantal' process because low InsP3 concentrations mobilize less Ca2+ than high concentrations and a submaximal concentration does not release all the InsP3-mobilizable Ca2+. However, some recent reports questioned the generally accepted view that a low dose of InsP3 is unable to empty the whole store. We have now challenged the stores of permeabilized A7r5 cells in InsP3 for much longer periods than previously reported, to assess directly whether the slow phase of the release would empty the whole store (a non-quantal response) or only a fraction of it (a quantal response). Addition of a maximal [InsP3] at the end of a prolonged (92 min) stimulation with a submaximal [InsP3] resulted in additional Ca2+ release. Experiments in which the stores were challenged with different submaximal InsP3 concentrations for long time periods revealed that a lower [InsP3] never released the same amount of Ca2+ as a higher [InsP3]. This quantal pattern of Ca2+ release occurred both at 25 degrees C and at 4 degrees C. There was a time-dependent increase in the fraction of Ca2+ recruited by the lower compared with the higher [InsP3]. This recruitment of Ca2+ persisted if the [InsP3] was decreased, but was largely prevented by palmitoyl-CoA, a potent blocker of the luminal Ca2+ translocation between individual store units. ATP, in the presence of InsP3, released Ca2+ under conditions permitting the recruitment of no additional InsP3 receptors, indicating that an all-or-none emptying of a fraction of the stores cannot be the only mechanism responsible for quantal Ca2+ release in A7r5 cells. We conclude that some of the previously published evidence for a non-quantal Ca2+ release pattern should be reinterpreted. PMID:9173870

  1. Ecological determinism increases with organism size.

    PubMed

    Farjalla, Vinicius F; Srivastava, Diane S; Marino, Nicholas A C; Azevedo, Fernanda D; Dib, Viviane; Lopes, Paloma M; Rosado, Alexandre S; Bozelli, Reinaldo L; Esteves, Francisco A

    2012-07-01

    After much debate, there is an emerging consensus that the composition of many ecological communities is determined both by species traits, as proposed by niche theory, as well as by chance events. A critical question for ecology is, therefore, which attributes of species predict the dominance of deterministic or stochastic processes. We outline two hypotheses by which organism size could determine which processes structure ecological communities, and we test these hypotheses by comparing the community structure in bromeliad phytotelmata of three groups of organisms (bacteria, zooplankton, and macroinvertebrates) that encompass a 10 000-fold gradient in body size, but live in the same habitat. Bacteria had no habitat associations, as would be expected from trait-neutral stochastic processes, but still showed exclusion among species pairs, as would be expected from niche-based processes. Macroinvertebrates had strong habitat and species associations, indicating niche-based processes. Zooplankton, with body size between bacteria and macroinvertebrates, showed intermediate habitat associations. We concluded that a key niche process, habitat filtering, strengthened with organism size, possibly because larger organisms are both less plastic in their fundamental niches and more able to be selective in dispersal. These results suggest that the relative importance of deterministic and stochastic processes may be predictable from organism size. PMID:22919920

  2. Can treatment increase the epidemic size?

    PubMed

    Xiao, Yanyu; Brauer, Fred; Moghadas, Seyed M

    2016-01-01

    Antiviral treatment is one of the key pharmacological interventions against many infectious diseases. This is particularly important in the absence of preventive measures such as vaccination. However, the evolution of drug-resistance in treated patients and its subsequent spread to the population pose significant impediments to the containment of disease epidemics using treatment. Previous models of population dynamics of influenza infection have shown that in the presence of drug-resistance, the epidemic final size (i.e., the total number of infections throughout the epidemic) is affected by the treatment rate. These models, through simulation experiments, illustrate the existence of an optimal treatment rate, not necessarily the highest possible rate, for minimizing the epidemic final size. However, the conditions for the existence of such an optimal treatment rate have never been found. Here, we provide these conditions for a class of models covered in the literature previously, and investigate the combination effect of treatment and transmissibility of the drug-resistant pathogen strain on the epidemic final size. For the first time, we obtain the final size relations for an epidemic model with two strains of a pathogen (i.e., drug-sensitive and drug-resistant). We also discuss this model with specific functional forms of de novo resistance emergence, and illustrate the theoretical findings with numerical simulations. PMID:25925242

  3. Effect of N-acetylaspartylglutamate (NAAG) on non-quantal and spontaneous quantal release of acetylcholine at the neuromuscular synapse of rat.

    PubMed

    Malomouzh, Artem I; Nikolsky, Eugen E; Lieberman, Edward M; Sherman, Jessica A; Lubischer, Jane L; Grossfeld, Robert M; Urazaev, Albert Kh

    2005-07-01

    N-Acetylaspartylglutamate (NAAG), known to be present in rat motor neurons, may participate in neuronal modulation of non-quantal secretion of acetylcholine (ACh) from motor nerve terminals. Non-quantal release of ACh was estimated by the amplitude of the endplate membrane hyperpolarization (H-effect) caused by inhibition of nicotinic receptors by (+)-tubocurarine and acetylcholinesterase by armin (diethoxy-p-nitrophenyl phosphate). Application of exogenous NAAG decreased the H-effect in a dose-dependent manner. The reduction of the H-effect by NAAG was completely removed when N-acetyl-beta-aspartylglutamate (betaNAAG) or 2-(phosphonomethyl)-pentanedioic acid (2-PMPA) was used to inhibit glutamate carboxypeptidase II (GCP II), a presynaptic Schwann cell membrane-associated ectoenzyme that hydrolyzes NAAG to glutamate and N-acetylaspartate. Bath application of glutamate decreased the H-effect similarly to the action of NAAG but N-acetylaspartate was without effect. Inhibition of NMDA receptors by dl-2-amino-5-phosphopentanoic acid, (+)-5-methyl-10,11-dihydro-5H-dibenzocyclohepten-5,10-imine (MK801), and 7-chlorokynurenic acid or inhibition of muscle nitric oxide synthase (NO synthase) by N(G)-nitro-l-arginine methyl ester and 3-bromo-7-nitroindazole completely prevented the decrease of the H-effect by NAAG. These results suggest that glutamate, produced by enzymatic hydrolysis of bath-applied NAAG, can modulate non-quantal secretion of ACh from the presynaptic terminal of the neuromuscular synapse via activation of postsynaptic NMDA receptors and synthesis of nitric oxide (NO) in muscle fibers. NAAG also increased the frequency of miniature endplate potentials (mEPPs) generated by spontaneous quantal secretion of ACh, whereas the mean amplitude and time constants for rise time and for decay of mEPPs did not change. PMID:15953368

  4. The quantal component of synaptic transmission from sensory hair cells to the vestibular calyx.

    PubMed

    Highstein, Stephen M; Mann, Mary Anne; Holstein, Gay R; Rabbitt, Richard D

    2015-06-01

    Spontaneous and stimulus-evoked excitatory postsynaptic currents (EPSCs) were recorded in calyx nerve terminals from the turtle vestibular lagena to quantify key attributes of quantal transmission at this synapse. On average, EPSC events had a magnitude of ∼ 42 pA, a rise time constant of τ(0) ∼ 229 μs, decayed to baseline with a time constant of τ(R) ∼ 690 μs, and carried ∼ 46 fC of charge. Individual EPSCs varied in magnitude and decay time constant. Variability in the EPSC decay time constant was hair cell dependent and due in part to a slow protraction of the EPSC in some cases. Variability in EPSC size was well described by an integer summation of unitary quanta, with each quanta of glutamate gating a unitary postsynaptic current of ∼ 23 pA. The unitary charge was ∼ 26 fC for EPSCs with a simple exponential decay and increased to ∼ 48 fC for EPSCs exhibiting a slow protraction. The EPSC magnitude and the number of simultaneous unitary quanta within each event increased with presynaptic stimulus intensity. During tonic hair cell depolarization, both the EPSC magnitude and event rate exhibited adaptive run down over time. Present data from a reptilian calyx are remarkably similar to noncalyceal vestibular synaptic terminals in diverse species, indicating that the skewed EPSC size distribution and multiquantal release might be an ancestral property of inner ear ribbon synapses. PMID:25878150

  5. The quantal component of synaptic transmission from sensory hair cells to the vestibular calyx

    PubMed Central

    Highstein, Stephen M.; Mann, Mary Anne; Holstein, Gay R.

    2015-01-01

    Spontaneous and stimulus-evoked excitatory postsynaptic currents (EPSCs) were recorded in calyx nerve terminals from the turtle vestibular lagena to quantify key attributes of quantal transmission at this synapse. On average, EPSC events had a magnitude of ∼42 pA, a rise time constant of τ0 ∼229 μs, decayed to baseline with a time constant of τR ∼690 μs, and carried ∼46 fC of charge. Individual EPSCs varied in magnitude and decay time constant. Variability in the EPSC decay time constant was hair cell dependent and due in part to a slow protraction of the EPSC in some cases. Variability in EPSC size was well described by an integer summation of unitary quanta, with each quanta of glutamate gating a unitary postsynaptic current of ∼23 pA. The unitary charge was ∼26 fC for EPSCs with a simple exponential decay and increased to ∼48 fC for EPSCs exhibiting a slow protraction. The EPSC magnitude and the number of simultaneous unitary quanta within each event increased with presynaptic stimulus intensity. During tonic hair cell depolarization, both the EPSC magnitude and event rate exhibited adaptive run down over time. Present data from a reptilian calyx are remarkably similar to noncalyceal vestibular synaptic terminals in diverse species, indicating that the skewed EPSC size distribution and multiquantal release might be an ancestral property of inner ear ribbon synapses. PMID:25878150

  6. The effects of increased serving sizes on consumption.

    PubMed

    Hydock, Chris; Wilson, Anne; Easwar, Karthik

    2016-06-01

    The US Food and Drug Administration recently revealed that it is considering modifying the Nutrition Facts Panels required on packaged foods. One proposed change is increasing serving sizes included on labels, which has two potential implications. Larger serving sizes could increase consumption if consumers use the serving sizes displayed as a reference point for their own consumption (McFerran et al., 2010). Alternatively, larger serving sizes that depict increased values of negative nutrients (e.g. calories) could lead consumers to perceive foods as less healthy, thereby reducing consumption (Russo et al., 1986). In study 1 (Online sample, N = 208, Mage = 32, SDage = 12), participants saw pictures of packaged food items and nutrition labels. The labels, depicted either the existing or larger serving size. Across all foods, larger serving sizes led to lower health perceptions. Labels with larger serving sizes were rated as more representative of typical consumption. Study 2 (Online sample, N = 347, Mage = 31, SDage = 10) used the same design as study 1, but required participants to virtually portion foods. While serving sizes did not impact the amount of food consumers portioned, those who saw labels with larger serving sizes estimated that they portioned out more calories. In study 3 (Student sample, N = 198, Mage = 20, SDage = 1), participants were given M&Ms to eat, paired with a nutritional label depicting either the current or a larger serving size, while participating in unrelated surveys. Participants presented with the larger serving size label consumed less than those presented with the current serving size label. Together, the results suggest that the proposed increase in serving sizes on Nutrition Facts Panels could lower consumption of high-calorie foods. PMID:26928789

  7. Parkinsonian patients reduce their stroke size with increased processing demands.

    PubMed

    Van Gemmert, A W; Teulings, H L; Stelmach, G E

    2001-12-01

    Parkinson's disease (PD) patients often show reductions in writing size (micrographia) as the length of the text they produce increases. The cause for these reductions in stroke size are not well understood. Reductions in stroke size could be associated with either concurrent processing demands that result from the coordination and control of fingers, wrist, and arm during writing and the processing of future words or increased extension of the wrist joint as the execution of the writing progresses to the right across the page, resulting in increased stiffness in the pen-limb system. Parkinson's patients and elderly controls wrote phrases of different lengths with target patterns in various serial positions. When the number of words to be written increased, PD patients reduced their stroke size of the initial target pattern, while the elderly controls did not reduce their stroke size. There was no systematic change in stroke size of the second pattern as function of serial position. This result suggests that PD patients reduce the size of their handwriting strokes when concurrent processing load increases. PMID:11748904

  8. Larger brain size indirectly increases vulnerability to extinction in mammals.

    PubMed

    Gonzalez-Voyer, Alejandro; González-Suárez, Manuela; Vilà, Carles; Revilla, Eloy

    2016-06-01

    Although previous studies have addressed the question of why large brains evolved, we have limited understanding of potential beneficial or detrimental effects of enlarged brain size in the face of current threats. Using novel phylogenetic path analysis, we evaluated how brain size directly and indirectly, via its effects on life history and ecology, influences vulnerability to extinction across 474 mammalian species. We found that larger brains, controlling for body size, indirectly increase vulnerability to extinction by extending the gestation period, increasing weaning age, and limiting litter sizes. However, we found no evidence of direct, beneficial, or detrimental effects of brain size on vulnerability to extinction, even when we explicitly considered the different types of threats that lead to vulnerability. Order-specific analyses revealed qualitatively similar patterns for Carnivora and Artiodactyla. Interestingly, for Primates, we found that larger brain size was directly (and indirectly) associated with increased vulnerability to extinction. Our results indicate that under current conditions, the constraints on life history imposed by large brains outweigh the potential benefits, undermining the resilience of the studied mammals. Contrary to the selective forces that have favored increased brain size throughout evolutionary history, at present, larger brains have become a burden for mammals. PMID:27159368

  9. The Evolution of Matter: The Quantal Unity of Evolution

    NASA Astrophysics Data System (ADS)

    Farre, George L.

    2002-09-01

    This paper is a brief sketch of the mechanisms that govern the construction of natural systems. Consequently, relatively little will be said about the external circumstances of their diversification. As nature has relatively few tricks in its bag, what follows may be viewed as an overview of the quantal unit of evolution (QUE), modally indexed.

  10. Computer Simulation of Quantal Dose-Response Relationships.

    ERIC Educational Resources Information Center

    McGilliard, Kip L.

    1985-01-01

    Describes a program which simulates animal pharmacology experiments involving "all-or-none" responses. Use of the Applesoft BASIC program in the pharmacology teaching laboratory provides students with a rapid and economical way to gain experience in the design and statistical analysis of quantal dose-response experiments. Information on obtaining…

  11. Genome size increases in recently diverged hornwort clades.

    PubMed

    Bainard, Jillian D; Villarreal, Juan Carlos

    2013-08-01

    As our knowledge of plant genome size estimates continues to grow, one group has continually been neglected: the hornworts. Hornworts (Anthocerotophyta) have been traditionally grouped with liverworts and mosses because they share a haploid dominant life cycle; however, recent molecular studies place hornworts as the sister lineage to extant tracheophytes. Given the scarcity of information regarding the DNA content of hornworts, our objective was to estimate the 1C-value for a range of hornwort species within a phylogenetic context. Using flow cytometry, we estimated genome size for 36 samples representing 24 species. This accounts for roughly 10% of known hornwort species. Haploid genome sizes (1C-value) ranged from 160 Mbp or 0.16 pg (Leiosporoceros dussii) to 719 Mbp or 0.73 pg (Nothoceros endiviifolius). The average 1C-value was 261 ± 104 Mbp (0.27 ± 0.11 pg). Ancestral reconstruction of genome size on a hornwort phylogeny suggests a small ancestral genome size and revealed increases in genome size in the most recently divergent clades. Much more work is needed to understand DNA content variation in this phylogenetically important group, but this work has significantly increased our knowledge of genome size variation in hornworts. PMID:24168626

  12. Economic Effects of Increased Control Zone Sizes in Conflict Resolution

    NASA Technical Reports Server (NTRS)

    Datta, Koushik

    1998-01-01

    A methodology for estimating the economic effects of different control zone sizes used in conflict resolutions between aircraft is presented in this paper. The methodology is based on estimating the difference in flight times of aircraft with and without the control zone, and converting the difference into a direct operating cost. Using this methodology the effects of increased lateral and vertical control zone sizes are evaluated.

  13. Increasing the Size of a Piece of Popcorn

    NASA Astrophysics Data System (ADS)

    Quinn, Paul; Hong, Daniel C.; Both, Joseph

    2003-03-01

    Popcorn is an extremely popular snack food in the world today. Thermodynamics can be used to analyze how popcorn is produced. By treating the popping mechanism of the corn as a thermodynamic expansion, a method of increasing the volume or size of a kernel of popcorn can be studied. By lowering the pressure surrounding the unpopped kernel, one can use a thermodynamic argument to show that the expanded volume of the kernel when it pops must increase. In this project, a variety of experiments are run to test the validity of this theory. The results show that there is a significant increase in the average kernel size when the pressure of the surroundings is reduced.

  14. Increasing the size of a piece of popcorn

    NASA Astrophysics Data System (ADS)

    Quinn, Paul V.; Hong, Daniel C.; Both, J. A.

    2005-08-01

    Popcorn is an extremely popular snack food in the world today. Thermodynamics can be used to analyze how popcorn is produced. By treating the popping mechanism of the corn as a thermodynamic expansion, a method of increasing the volume or size of a kernel of popcorn can be studied. By lowering the pressure surrounding the unpopped kernel, one can use a thermodynamic argument to show that the expanded volume of the kernel when it pops must increase. In this project, a variety of experiments are run to test the qualitative validity of this theory. The results show that there is a significant increase in the average kernel size when the pressure of the surroundings is reduced.

  15. Rate of tree carbon accumulation increases continuously with tree size.

    PubMed

    Stephenson, N L; Das, A J; Condit, R; Russo, S E; Baker, P J; Beckman, N G; Coomes, D A; Lines, E R; Morris, W K; Rüger, N; Alvarez, E; Blundo, C; Bunyavejchewin, S; Chuyong, G; Davies, S J; Duque, A; Ewango, C N; Flores, O; Franklin, J F; Grau, H R; Hao, Z; Harmon, M E; Hubbell, S P; Kenfack, D; Lin, Y; Makana, J-R; Malizia, A; Malizia, L R; Pabst, R J; Pongpattananurak, N; Su, S-H; Sun, I-F; Tan, S; Thomas, D; van Mantgem, P J; Wang, X; Wiser, S K; Zavala, M A

    2014-03-01

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence. PMID:24429523

  16. Rate of tree carbon accumulation increases continuously with tree size

    USGS Publications Warehouse

    Stephenson, N.L.; Das, A.J.; Condit, R.; Russo, S.E.; Baker, P.J.; Beckman, N.G.; Coomes, D.A.; Lines, E.R.; Morris, W.K.; Rüger, N.; Álvarez, E.; Blundo, C.; Bunyavejchewin, S.; Chuyong, G.; Davies, S.J.; Duque, Á.; Ewango, C.N.; Flores, O.; Franklin, J.F.; Grau, H.R.; Hao, Z.; Harmon, M.E.; Hubbell, S.P.; Kenfack, D.; Lin, Y.; Makana, J.-R.; Malizia, A.; Malizia, L.R.; Pabst, R.J.; Pongpattananurak, N.; Su, S.-H.; Sun, I-F.; Tan, S.; Thomas, D.; van Mantgem, P.J.; Wang, X.; Wiser, S.K.; Zavala, M.A.

    2014-01-01

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage—increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to understand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  17. Rate of tree carbon accumulation increases continuously with tree size

    NASA Astrophysics Data System (ADS)

    Stephenson, N. L.; Das, A. J.; Condit, R.; Russo, S. E.; Baker, P. J.; Beckman, N. G.; Coomes, D. A.; Lines, E. R.; Morris, W. K.; Rüger, N.; Álvarez, E.; Blundo, C.; Bunyavejchewin, S.; Chuyong, G.; Davies, S. J.; Duque, Á.; Ewango, C. N.; Flores, O.; Franklin, J. F.; Grau, H. R.; Hao, Z.; Harmon, M. E.; Hubbell, S. P.; Kenfack, D.; Lin, Y.; Makana, J.-R.; Malizia, A.; Malizia, L. R.; Pabst, R. J.; Pongpattananurak, N.; Su, S.-H.; Sun, I.-F.; Tan, S.; Thomas, D.; van Mantgem, P. J.; Wang, X.; Wiser, S. K.; Zavala, M. A.

    2014-03-01

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  18. Trees increase their P:N ratio with size

    PubMed Central

    Sardans, J; Peñuelas, J.

    2015-01-01

    Aim Phosphorus (P) tends to become limiting in aging terrestrial ecosystems, and its resorption efficiency is higher than for other elements such as nitrogen (N). We thus hypothesized that trees should store more P than those other elements such as N when tree size increases and that this process should be enhanced in slow-growing late successional trees. Location Catalan forests. Methods We have used data from the Catalan Forest Inventory that contains field data of the P and N contents of total aboveground, foliar and woody biomasses of the diverse Mediterranean, temperate and alpine forests of Catalonia (1018 sites). We used correlation and general lineal models (GLM) to analyze the allometric relationships between nutrient contents of different aboveground biomass fractions (foliar, branches and stems) and total aboveground biomass. Results Aboveground forest P content increases proportionally more than aboveground forest N content with increasing aboveground biomass. Two mechanisms underlie this. First, woody biomass increases proportionally more than foliar biomass having woody biomass higher P:N ratio than foliar biomass. Second, wood P:N ratio increases with tree size. These results are consistent with the generally higher foliar resorption of P than of N. Slow-growing species accumulate more P in total aboveground with size than fast-growing species mainly as a result of their large capacity to store P in wood. Main conclusions Trees may have thus developed long-term adaptive mechanisms to store P in biomass, mainly in wood, thereby slowing the loss of P from the ecosystems, reducing its availability for competitors, and implying an increase in the P:N ratio in forest biomass with aging. This trend to accumulate more P than N with size is more accentuated in slow-growing, large, long-living species of late successional stages. This way they partly counterbalance the gradual decrease of P in the soil. PMID:25983656

  19. Effect of hypertonicity on augmentation and potentiation and on corresponding quantal parameters of transmitter release.

    PubMed

    Cheng, H; Miyamoto, M D

    1999-03-01

    Augmentation and (posttetanic) potentiation are two of the four components comprising the enhanced release of transmitter following repetitive nerve stimulation. To examine the quantal basis of these components under isotonic and hypertonic conditions, we recorded miniature endplate potentials (MEPPs) from isolated frog (Rana pipiens) cutaneous pectoris muscles, before and after repetitive nerve stimulation (40 s at 80 Hz). Continuous recordings were made in low Ca2+ high Mg2+ isotonic Ringer solution, in Ringer that was made hypertonic with 100 mM sucrose, and in wash solution. Estimates were obtained of m (no. of quanta released), n (no. of functional release sites), p (mean probability of release), and vars p (spatial variance in p), using a method that employed MEPP counts. Hypertonicity abolished augmentation without affecting potentiation. There were prolonged poststimulation increases in m, n, and p and a marked but transient increase in vars p in the hypertonic solution. All effects were completely reversed with wash. The time constants of decay for potentiation and for vars p were virtually identical. The results are consistent with the notion that augmentation is caused by Ca2+ influx through voltage-gated calcium channels and that potentiation is due to Na+-induced Ca2+ release from mitochondria. The results also demonstrate the utility of this approach for analyzing the dynamics of quantal transmitter release. PMID:10085369

  20. Pupillometry reveals increased pupil size during indirect request comprehension.

    PubMed

    Tromp, Johanne; Hagoort, Peter; Meyer, Antje S

    2016-06-01

    Fluctuations in pupil size have been shown to reflect variations in processing demands during lexical and syntactic processing in language comprehension. An issue that has not received attention is whether pupil size also varies due to pragmatic manipulations. In two pupillometry experiments, we investigated whether pupil diameter was sensitive to increased processing demands as a result of comprehending an indirect request versus a direct statement. Adult participants were presented with 120 picture-sentence combinations that could be interpreted either as an indirect request (a picture of a window with the sentence "it's very hot here") or as a statement (a picture of a window with the sentence "it's very nice here"). Based on the hypothesis that understanding indirect utterances requires additional inferences to be made on the part of the listener, we predicted a larger pupil diameter for indirect requests than statements. The results of both experiments are consistent with this expectation. We suggest that the increase in pupil size reflects additional processing demands for the comprehension of indirect requests as compared to statements. This research demonstrates the usefulness of pupillometry as a tool for experimental research in pragmatics. PMID:26110545

  1. Super-size me: self biases increase to larger stimuli.

    PubMed

    Sui, Jie; Humphreys, Glyn W

    2015-04-01

    Prior work has shown that simple perceptual match responses to pairings of shapes and labels are more efficient if the pairing is associated with the participant (e.g., circle-you) than if it is associated with another familiar person (e.g., square-friend). There is a similar advantage for matching associations with high-value rewards (circle-£9) versus low-value rewards (square-£1) (Sui, He, & Humphreys Journal of Experimental Psychology: Human Perception and Performance, 38, 1105-1117, 2012). Here we evaluated the relations between the self- and reward-bias effects by introducing occasional trials in which the size of a shape was varied unexpectedly (large or small vs. a standard medium). Participants favored stimuli that were larger than the standard when stimuli were associated with the self, and this enhancement of self bias was predicted by the degree of self bias that participants showed to standard (medium) sized stimuli. Although we observed a correlation between the magnitudes of the self and reward biases over participants, reward-bias effects were not increased to large stimuli. The data suggest both overlapping and independent components of the self and reward biases, and that self biases are uniquely enhanced when stimuli increase in size, consistent with previously reported motivational biases favoring large stimuli. PMID:25112393

  2. Exercise training increases size of hippocampus and improves memory.

    PubMed

    Erickson, Kirk I; Voss, Michelle W; Prakash, Ruchika Shaurya; Basak, Chandramallika; Szabo, Amanda; Chaddock, Laura; Kim, Jennifer S; Heo, Susie; Alves, Heloisa; White, Siobhan M; Wojcicki, Thomas R; Mailey, Emily; Vieira, Victoria J; Martin, Stephen A; Pence, Brandt D; Woods, Jeffrey A; McAuley, Edward; Kramer, Arthur F

    2011-02-15

    The hippocampus shrinks in late adulthood, leading to impaired memory and increased risk for dementia. Hippocampal and medial temporal lobe volumes are larger in higher-fit adults, and physical activity training increases hippocampal perfusion, but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood remains unknown. Here we show, in a randomized controlled trial with 120 older adults, that aerobic exercise training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 y. We also demonstrate that increased hippocampal volume is associated with greater serum levels of BDNF, a mediator of neurogenesis in the dentate gyrus. Hippocampal volume declined in the control group, but higher preintervention fitness partially attenuated the decline, suggesting that fitness protects against volume loss. Caudate nucleus and thalamus volumes were unaffected by the intervention. These theoretically important findings indicate that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood, which is accompanied by improved memory function. PMID:21282661

  3. Individual increase in inbreeding allows estimating effective sizes from pedigrees.

    PubMed

    Gutiérrez, Juan Pablo; Cervantes, Isabel; Molina, Antonio; Valera, Mercedes; Goyache, Félix

    2008-01-01

    We present here a simple approach to obtain reliable estimates of the effective population size in real world populations via the computation of the increase in inbreeding for each individual (delta F(i)) in a given population. The values of delta F(i) are computed as t-root of 1 - (1 - F(i)) where F(i) is the inbreeding coefficient and t is the equivalent complete generations for each individual. The values of delta F computed for a pre-defined reference subset can be averaged and used to estimate effective size. A standard error of this estimate of N(e) can be further computed from the standard deviation of the individual increase in inbreeding. The methodology is demonstrated by applying it to several simulated examples and to a real pedigree in which other methodologies fail when considering reference subpopulations. The main characteristics of the approach and its possible use are discussed both for predictive purposes and for analyzing genealogies. PMID:18558071

  4. Increase in vertebral body size in postmenopausal women with osteoporosis.

    PubMed

    Briot, K; Kolta, S; Fechtenbaum, J; Said-Nahal, R; Benhamou, C L; Roux, C

    2010-08-01

    Bone geometry plays a prominent role in bone strength. Cross-sectional studies have shown that advancing age is associated with increasing diameter of long bones, related to both periostal apposition and endosteal resorption. However, there are few data provided by prospective studies, especially concerning the changes in vertebral body dimensions. The objective of this prospective study was to measure the changes occurring in the vertebral body size of women with postmenopausal osteoporosis. Three-year data from placebo groups of the SOTI and TROPOS trials, performed in women with postmenopausal osteoporosis, were used for this study. In these trials, patients underwent lateral radiographs of the thoracic and lumbar spine at baseline and annually over 3 years, according to standardized procedures. Six-point digitization method was used: the four corner points of the vertebral body from T4 to L4 are marked, as well as an additional point in the middle of the upper and lower endplates. From these 6 points, the vertebral body perimeter, area and depth were measured at baseline and at 3 years. The analysis excluded all vertebrae with prevalent or incident fracture. A total of 2017 postmenopausal women (mean age 73.4+/-6.1 years) with a mean lumbar spine T score of -3.1+/-1.5, and a mean femoral neck T score of -3.0+/-0.7 are included in the analysis. Vertebral body dimensions increased over 3 years, by 2.1+/-5.5% (mean depth+/-SD), by 1.7+/-8.3% (mean area+/-SD) and by 1.5+/-4.9% (mean perimeter+/-SD) at the thoracic level (T4 to T12). At the lumbar level (L1 to L4), these dimensions increased as well: 1.4+/-3.6% (mean depth+/-SD), 1.4+/-5.7% (mean area+/-SD), 0.7+/-2.9% (mean perimeter+/-SD). A significant increase in vertebral body size was observed for each vertebral level from T5 to L4 for each of these parameters (p<0.01). These prospective results demonstrate that vertebral body dimensions increase over 3 years in women with postmenopausal osteoporosis. PMID

  5. A Computer Simulation for Teaching Quantal Time Development

    NASA Astrophysics Data System (ADS)

    Styer, Daniel F.

    1996-11-01

    The computer program QMTime (for MS-DOS machines) enables students to simulate quantal time development in one dimension. A variety of initial wave packets (Gaussian, Lorentzian, etc.) can evolve in time under the influence of a variety of potential energy functions (step, ramp, square well, harmonic oscillator, etc.) with or without an external driving force. A novel visualization technique simultaneously displays the magnitude and phase of complex-valued wavefunctions. Either position-space or momentum-space wavefunctions, or both, can be shown. The program is particularly effective in demonstrating the classical limit of quantum mechanics. This program is part of the CUPS (Consortium for Upper level Physics Software) project.

  6. Skill improvement from increased ensemble size and model diversity

    NASA Astrophysics Data System (ADS)

    DelSole, Timothy; Nattala, Jyothi; Tippett, Michael K.

    2014-10-01

    This paper proposes an objective procedure for deciding if the skill of a combination of forecasts is significantly larger than that of a single forecast, and for deciding if the observed improvement is dominated by reduction of noise associated with ensemble averaging, or by addition of new predictable signals. Information theory provides an attractive framework for addressing these questions. The procedure is applied to El Niño-Southern Oscillation hindcasts from the North American Multimodel Ensemble (NMME) and reveals that the observed skill advantage of the NMME compared to individual models is substantially greater than that expected from increased ensemble size alone and is more consistent with the addition of new signals.

  7. Dynamics of quantal heating in electron systems with discrete spectra

    NASA Astrophysics Data System (ADS)

    Dietrich, Scott; Mayer, William; Vitkalov, Sergey; Bykov, A. A.

    2015-05-01

    The temporal evolution of quantal Joule heating of two-dimensional (2D) electrons in a GaAs quantum well placed in quantizing magnetic fields is studied using a difference-frequency method. The method is based on measurements of the electron conductivity oscillating at the beat frequency f =f1-f2 between two microwaves applied to the 2D system at frequencies f1 and f2. The method provides direct access to the dynamical characteristics of the heating and yields the inelastic-scattering time τi n of 2D electrons. The obtained τi n is strongly temperature dependent, varying from 0.13 ns at 5.5 K to 1 ns at 2.4 K in magnetic field B =0.333 T . When the temperature T exceeds the Landau-level separation, the relaxation rate 1 /τi n is proportional to T2, indicating electron-electron interaction as the dominant mechanism limiting the quantal heating. At lower temperatures, the rate tends to be proportional to T3, indicating considerable contribution from electron-phonon scattering.

  8. Experimentally increased badge size increases male competition and reduces male parental care in the collared flycatcher

    PubMed Central

    Qvarnstroöm, A.

    1997-01-01

    Experimental enlargement of sexually selected traits that are energetically cheap to produce is expected to reveal costs resulting from increased risk of predation or social competition. Given a trade-off between sexually selected traits and life history traits such costs may be expected to affect not only the males themselves but also their offspring. In this study I manipulated the size of the forehead patch, a sexually selected trait that functions as a badge of status in male collared flycatchersFicedula albicollis). First, I found that a male's likelihood to establish a breeding territory with respect to his original badge size was affected by the treatment such that old males (older than or equal to two years) with relatively small original badges enjoyed an increased likelihood of establishing a breeding territory while young males (yearlings) suffered a reduced likelihood of establishment when their badges were enlarged as compared to unchanged. Second, young males with enlarged badges that were able to establish a territory fed their nestlings less in relation to their females compared to the control males. However, the females adjusted their parental effort to such an extent that no significant differences were observed in total feeding rate nor in reproductive success between the two groups of males. These results suggest that experimentally enlarged badge size in the collared flycatcher may result in increased male competition and that males have to trade their effort spent in male contest against their parental effort.

  9. Increased incidence of spontaneous malformations in pups and increased litter size from pinealectomized dams.

    PubMed

    Kachi, Takashi; Tanaka, Dai; Watanabe, Seiji; Suzuki, Reiko; Tonosaki, Yoshikazu

    2004-06-01

    The aim of the present study was to clarify whether maternal pinealectomy increases: (i) the incidence of spontaneous malformations in offspring; and (ii) litter size. More than 30 female rats in each of the control groups (normal and sham-pinealectomized) and the pinealectomized group were mated repeatedly with normal male rats and pups were autopsied mostly before weaning. No malformations were seen in offspring from the normal and sham-pinealectomized groups (n = 350 and n = 736, respectively). In contrast, in offspring from pinealectomized mothers (n = 1123), spontaneous malformations were found in five (taillessness in three and unilateral hydronephrosis or large renal cyst in the other two) or maybe six (unilateral renal hypoplasia in another) pups. This increased incidence of malformations in the latter group was statistically significant (P < 0.034 or 0.017 (Fisher's exact test), respectively). The frequency of still-born cases was not higher in pups born from pinealectomized mothers. The mean litter size was larger in the pinealectomized group compared with the control groups (P < 0.005-0.001, Student's t-test) at the first delivery (at approximately 100 days of age), but was not different at later deliveries at older ages. Our results suggest that the maternal pineal hormone suppresses: (i) the incidence of spontaneous malformations in offspring until mothers reach an old age; and (ii) litter size during the reproductively maturational phase of life. PMID:15218625

  10. Direct measurement of ACh release from exposed frog nerve terminals: constraints on interpretation of non-quantal release.

    PubMed Central

    Grinnell, A D; Gundersen, C B; Meriney, S D; Young, S H

    1989-01-01

    1. Acetylcholine (ACh) release from enzymatically exposed frog motor nerve terminals has been measured directly with closely apposed outside-out clamped patches of Xenopus myocyte membrane, rich in ACh receptor channels. When placed close to the synaptic surface of the terminal, such a membrane patch detects both nerve-evoked patch currents (EPCs) and spontaneous quantal 'miniature' patch currents (MPCs), from a few micrometres length of the terminal, in response to ACh release from the nearest three to five active zones. 2. Chemical measurements of ACh efflux from whole preparations revealed a spontaneous release rate of 4.1 pmol (2 h)-1, and no significant difference in resting efflux between enzyme-treated and control preparations. The ratio of enzyme-treated to contralateral control muscle efflux averaged 1.17, indicating that enzyme treatment did not affect spontaneous ACh release. Vesamicol (1.7 microM), which blocks the ACh transporter in synaptic vesicles, decreased the spontaneous release of ACh to 67% of control. 3. In the absence of nerve stimulation, the frequency of single-channel openings recorded by outside-out patch probes adjacent to nerve terminals was very low (1-2 min-1), and little different at a distance of hundreds of micrometres, suggesting that if ACh was continually leaking from the terminal in a non-quantal fashion, the amount being released near active zone regions on the terminal was below the limit of detection with the patches. 4. Direct measurements of the sensitivity of the patches, coupled with calculated ACh flux rates, lead to the conclusion that the amount of ACh released non-quantally from the synaptic surface of the frog nerve terminal is less than one-tenth the amount expected if all non-quantal release is from this region of the terminal membrane. 5. Following a series of single nerve shocks or a 50 Hz train of nerve stimuli, the frequency of asynchronous single-channel openings increased for several seconds. This transient

  11. A Microscopic Quantal Model for Nuclear Collective Rotation

    SciTech Connect

    Gulshani, P.

    2007-10-26

    A microscopic, quantal model to describe nuclear collective rotation in two dimensions is derived from the many-nucleon Schrodinger equation. The Schrodinger equation is transformed to a body-fixed frame to decompose the Hamiltonian into a sum of intrinsic and rotational components plus a Coriolis-centrifugal coupling term. This Hamiltonian (H) is expressed in terms of space-fixed-frame particle coordinates and momenta by using commutator of H with a rotation angle. A unified-rotational-model type wavefunction is used to obtain an intrinsic Schrodinger equation in terms of angular momentum quantum number and two-body operators. A Hartree-Fock mean-field representation of this equation is then obtained and, by means of a unitary transformation, is reduced to a form resembling that of the conventional semi-classical cranking model when exchange terms and intrinsic spurious collective excitation are ignored.

  12. Adipocyte cell size enlargement involves plasma membrane area increase.

    PubMed

    Chowdhury, H H; Zorec, R

    2012-07-01

    The adipocyte enlargement is associated with an increase in the cytoplasmic lipid content, but how the plasma membrane area follows this increase is poorly understood. We monitored single-cell membrane surface area fluctuations, which mirror the dynamics of exocytosis and endocytosis. We employed the patch-clamp technique to measure membrane capacitance (C(m)), a parameter linearly related to the plasma membrane area. Specifically, we studied whether insulin affects membrane area dynamics in adipocytes. A five-minute cell exposure to insulin increased resting C(m) by 12 ± 4%; in controls the change in C(m) was not different from zero. We measured cell diameter of isolated rat adipocytes microscopically. Twenty-four hour exposure of cells to insulin resulted in a significant increase in cell diameter by 5.1 ± 0.6%. We conclude that insulin induces membrane area increase, which may in chronic hyperinsulinemia promote the enlargement of plasma membrane area, acting in concert with other insulin-mediated metabolic effects on adipocytes. PMID:22540353

  13. On being the right size: increased body size is associated with reduced telomere length under natural conditions.

    PubMed

    Ringsby, Thor Harald; Jensen, Henrik; Pärn, Henrik; Kvalnes, Thomas; Boner, Winnie; Gillespie, Robert; Holand, Håkon; Hagen, Ingerid Julie; Rønning, Bernt; Sæther, Bernt-Erik; Monaghan, Pat

    2015-12-01

    Evolution of body size is likely to involve trade-offs between body size, growth rate and longevity. Within species, larger body size is associated with faster growth and ageing, and reduced longevity, but the cellular processes driving these relationships are poorly understood. One mechanism that might play a key role in determining optimal body size is the relationship between body size and telomere dynamics. However, we know little about how telomere length is affected when selection for larger size is imposed in natural populations. We report here on the relationship between structural body size and telomere length in wild house sparrows at the beginning and end of a selection regime for larger parent size that was imposed for 4 years in an isolated population of house sparrows. A negative relationship between fledgling size and telomere length was present at the start of the selection; this was extended when fledgling size increased under the selection regime, demonstrating a persistent covariance between structural size and telomere length. Changes in telomere dynamics, either as a correlated trait or a consequence of larger size, could reduce potential longevity and the consequent trade-offs could thereby play an important role in the evolution of optimal body size. PMID:26631569

  14. Automated Maximum Likelihood Separation of Signal from Baseline in Noisy Quantal Data

    PubMed Central

    Bruno, William J.; Ullah, Ghanim; Daniel Mak, Don-On; Pearson, John E.

    2013-01-01

    Data recordings often include high-frequency noise and baseline fluctuations that are not generated by the system under investigation, which need to be removed before analyzing the signal for the system’s behavior. In the absence of an automated method, experimentalists fall back on manual procedures for removing these fluctuations, which can be laborious and prone to subjective bias. We introduce a maximum likelihood formalism for separating signal from a drifting baseline plus noise, when the signal takes on integer multiples of some value, as in ion channel patch-clamp current traces. Parameters such as the quantal step size (e.g., current passing through a single channel), noise amplitude, and baseline drift rate can all be optimized automatically using the expectation-maximization algorithm, taking the number of open channels (or molecules in the on-state) at each time point as a hidden variable. Our goal here is to reconstruct the signal, not model the (possibly highly complex) underlying system dynamics. Thus, our likelihood function is independent of those dynamics. This may be thought of as restricting to the simplest possible hidden Markov model for the underlying channel current, in which successive measurements of the state of the channel(s) are independent. The resulting method is comparable to an experienced human in terms of results, but much faster. FORTRAN 90, C, R, and JAVA codes that implement the algorithm are available for download from our website. PMID:23823225

  15. Automated maximum likelihood separation of signal from baseline in noisy quantal data.

    PubMed

    Bruno, William J; Ullah, Ghanim; Mak, Don-On Daniel; Pearson, John E

    2013-07-01

    Data recordings often include high-frequency noise and baseline fluctuations that are not generated by the system under investigation, which need to be removed before analyzing the signal for the system's behavior. In the absence of an automated method, experimentalists fall back on manual procedures for removing these fluctuations, which can be laborious and prone to subjective bias. We introduce a maximum likelihood formalism for separating signal from a drifting baseline plus noise, when the signal takes on integer multiples of some value, as in ion channel patch-clamp current traces. Parameters such as the quantal step size (e.g., current passing through a single channel), noise amplitude, and baseline drift rate can all be optimized automatically using the expectation-maximization algorithm, taking the number of open channels (or molecules in the on-state) at each time point as a hidden variable. Our goal here is to reconstruct the signal, not model the (possibly highly complex) underlying system dynamics. Thus, our likelihood function is independent of those dynamics. This may be thought of as restricting to the simplest possible hidden Markov model for the underlying channel current, in which successive measurements of the state of the channel(s) are independent. The resulting method is comparable to an experienced human in terms of results, but much faster. FORTRAN 90, C, R, and JAVA codes that implement the algorithm are available for download from our website. PMID:23823225

  16. Increasing portion sizes of fruits and vegetables in an elementary school lunch program can increase fruit and vegetable consumption.

    PubMed

    Miller, Nicole; Reicks, Marla; Redden, Joseph P; Mann, Traci; Mykerezi, Elton; Vickers, Zata

    2015-08-01

    Increasing portion size can increase children's consumption of food. The goal of this study was to determine whether increasing the portion sizes of fruits and vegetables in an elementary school cafeteria environment would increase children's consumption of them. We measured each child's consumption of the fruit and vegetables served in a cafeteria line on a control day (normal cafeteria procedures) and on two intervention days. When we increased the portion size of 3 of the 4 fruits and vegetables by about 50%, children who took those foods increased their consumption of them. Although this was an effective strategy for increasing fruit and vegetable consumption among students who took those foods, many children chose not to take any fruits or vegetables. Further efforts are needed to increase children's selection and consumption of fruits and vegetables in an environment of competing foods of higher palatability. PMID:25958117

  17. Receptor-mediated presynaptic facilitation of quantal release of acetylcholine induced by pralidoxime in Aplysia.

    PubMed

    Fossier, P; Baux, G; Poulain, B; Tauc, L

    1990-09-01

    1. Possible interactions of contrathion (pralidoxime sulfomethylate), a reactivator of phosphorylated acetylcholinesterase (AChE), with the regulation of cholinergic transmission were investigated on an identified synapse in the buccal ganglion of Aplysia californica. 2. Transmitter release was evoked either by a presynaptic action potential or, under voltage clamp, by a long depolarization of the presynaptic cell. At concentrations higher than 10(-5) M, bath-applied contrathion decreased the amplitude of miniature postsynaptic currents and increased their decay time. At the same time, the quantal release of ACh was transiently facilitated. The facilitatory effect of contrathion was prevented by tubocurarine but not by atropine. Because in this preparation, these drugs block, respectively, the presynaptic nicotinic-like and muscarinic-like receptors involved in positive and negative feedback of ACh release, we proposed that contrathion activates presynaptic nicotinic-like receptors. 3. Differential desensitization of the presynaptic receptors is proposed to explain the transience of the facilitatory action of contrathion on ACh release. 4. The complexity of the synaptic action of contrathion raises the possibility that its therapeutic effects in AChE poisonings are not limited to AChE reactivation. PMID:2253262

  18. Increasing precipitation event size increases aboveground net primary productivity in a semi-arid grassland.

    PubMed

    Heisler-White, Jana L; Knapp, Alan K; Kelly, Eugene F

    2008-11-01

    Water availability is the primary constraint to aboveground net primary productivity (ANPP) in many terrestrial biomes, and it is an ecosystem driver that will be strongly altered by future climate change. Global circulation models predict a shift in precipitation patterns to growing season rainfall events that are larger in size but fewer in number. This "repackaging" of rainfall into large events with long intervening dry intervals could be particularly important in semi-arid grasslands because it is in marked contrast to the frequent but small events that have historically defined this ecosystem. We investigated the effect of more extreme rainfall patterns on ANPP via the use of rainout shelters and paired this experimental manipulation with an investigation of long-term data for ANPP and precipitation. Experimental plots (n = 15) received the long-term (30-year) mean growing season precipitation quantity; however, this amount was distributed as 12, six, or four events applied manually according to seasonal patterns for May-September. The long-term mean (1940-2005) number of rain events in this shortgrass steppe was 14 events, with a minimum of nine events in years of average precipitation. Thus, our experimental treatments pushed this system beyond its recent historical range of variability. Plots receiving fewer, but larger rain events had the highest rates of ANPP (184 +/- 38 g m(-2)), compared to plots receiving more frequent rainfall (105 +/- 24 g m(-2)). ANPP in all experimental plots was greater than long-term mean ANPP for this system (97 g m(-2)), which may be explained in part by the more even distribution of applied rain events. Soil moisture data indicated that larger events led to greater soil water content and likely permitted moisture penetration to deeper in the soil profile. These results indicate that semi-arid grasslands are capable of responding immediately and substantially to forecast shifts to more extreme precipitation patterns. PMID

  19. Variability of Vowel Formant Frequencies and the Quantal Theory of Speech: A First Report

    PubMed Central

    Pisoni, David B.

    2012-01-01

    This paper reports the results of a study in which variability of formant frequencies for different vowels was examined with regard to several predictions derived from the quantal theory of speech. Two subjects were required to reproduce eight different steady-state synthetic vowels which were presented repeatedly in a randomized order. Spectral analysis was carried out on the vocal responses in order to obtain means and standard deviations of the vowel formant frequencies. In the spirit of the quantal theory, it was predicted that the points vowel, /i/, /a/ and /u/ would show lower standard deviations than the nonpoint vowels because these vowels are assumed to be produced at places in the vocal tract where small perturbations in articulation produce only minimal changes in the resulting formant frequencies. That is, these vowels are assumed to be quantal vowels. The results of this study provided little support for the hypothesis under consideration. A discussion of the outcome of the results as well as some speculation as to its failure to find support for the quantal theory is provided in the report. Several final comments are also offered about computer simulation studies of speech production and the need for additional empirical studies on vowel production with real talkers. PMID:7280032

  20. Independent Sources of Quantal Variability at Single Glutamatergic Synapses

    PubMed Central

    Franks, Kevin M.; Stevens, Charles F.; Sejnowski, Terrence J.

    2010-01-01

    Variability in the size of single postsynaptic responses is a feature of most central neurons, although the source of this variability is not completely understood. The dominant source of variability could be either intersynaptic or intrasynaptic. To quantitatively examine this question, a biophysically realistic model of an idealized central axospinous synapse was used to assess mechanisms underlying synaptic variability measurements. Three independent sources of variability were considered: stochasticity of postsynaptic receptors (“channel noise”), variations of glutamate concentration in the synaptic cleft (Δq), and differences in the potency of vesicles released from different locations on the active zone [release-location dependence (RLD)]. As expected, channel noise was small (8% of the total variance) and Δq was the dominant source of variability (58% of total variance). Surprisingly, RLD accounted for a significant amount of variability (36%). Our simulations show that potency of release sites decreased with a length constant of ~100 nm, and that receptors were not activated by release events >300 nm away, which is consistent with the observation that single active zones are rarely >300 nm. RLD also predicts that the manner in which receptors are added or removed from synapses can dramatically affect the nature of the synaptic response, with increasing receptor density being more efficient than merely increasing synaptic area. Saturation levels and synaptic geometry were also important in determining the size and shape of the distribution of amplitudes recorded at different synapses. PMID:12716926

  1. Life history evolution and cellular mechanisms associated with increased size in high-altitude Drosophila.

    PubMed

    Lack, Justin B; Yassin, Amir; Sprengelmeyer, Quentin D; Johanning, Evan J; David, Jean R; Pool, John E

    2016-08-01

    Understanding the physiological and genetic basis of growth and body size variation has wide-ranging implications, from cancer and metabolic disease to the genetics of complex traits. We examined the evolution of body and wing size in high-altitude Drosophila melanogaster from Ethiopia, flies with larger size than any previously known population. Specifically, we sought to identify life history characteristics and cellular mechanisms that may have facilitated size evolution. We found that the large-bodied Ethiopian flies laid significantly fewer but larger eggs relative to lowland, smaller-bodied Zambian flies. The highland flies were found to achieve larger size in a similar developmental period, potentially aided by a reproductive strategy favoring greater provisioning of fewer offspring. At the cellular level, cell proliferation was a strong contributor to wing size evolution, but both thorax and wing size increases involved important changes in cell size. Nuclear size measurements were consistent with elevated somatic ploidy as an important mechanism of body size evolution. We discuss the significance of these results for the genetic basis of evolutionary changes in body and wing size in Ethiopian D. melanogaster. PMID:27547363

  2. 43 CFR 4300.54 - Can BLM increase the size of the land in my permit?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION; ALASKA; REINDEER; GENERAL Changes in the Size of the Permit Area § 4300.54 Can BLM increase the... if BLM determines that the area is too small for the number of reindeer you are grazing. BLM...

  3. 43 CFR 4300.54 - Can BLM increase the size of the land in my permit?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION; ALASKA; REINDEER; GENERAL Changes in the Size of the Permit Area § 4300.54 Can BLM increase the... if BLM determines that the area is too small for the number of reindeer you are grazing. BLM...

  4. 43 CFR 4300.54 - Can BLM increase the size of the land in my permit?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ADMINISTRATION; ALASKA; REINDEER; GENERAL Changes in the Size of the Permit Area § 4300.54 Can BLM increase the... if BLM determines that the area is too small for the number of reindeer you are grazing. BLM...

  5. 43 CFR 4300.54 - Can BLM increase the size of the land in my permit?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ADMINISTRATION; ALASKA; REINDEER; GENERAL Changes in the Size of the Permit Area § 4300.54 Can BLM increase the... if BLM determines that the area is too small for the number of reindeer you are grazing. BLM...

  6. Culling experiments demonstrate size-class specific biomass increases with mortality.

    PubMed

    Schröder, A; Persson, L; de Roos, A M

    2009-02-24

    Size-selective mortality inevitably leads to a decrease in population density and exerts a direct negative effect on targeted size classes. But density and population size structure are also shaped by food-dependent processes, such as individual growth, maturation, and reproduction. Mortality relaxes competition and thereby alters the dynamic interplay among these processes. As shown by the recently developed size-structured theory, which can account for food-dependent individual performance, this altered interplay can lead to overcompensatory responses in size class-specific biomass, with increasing mortality. We experimentally tested this theory by subjecting laboratory fish populations to a range of size-selective mortality rates. Overall, the results were in agreement with theoretical predictions. Biomass of the juvenile size class increased above control levels at intermediate adult mortality rates and thereafter declined at high mortality rates. Juvenile biomass also increased when juveniles themselves were subjected to intermediate mortality rates. Biomass in other size classes decreased with mortality. Such biomass overcompensation can have wide-ranging implications for communities and food webs, including a high sensitivity of top predators to irreversible catastrophic collapses, the establishment of alternative stable community states, and the promotion of coexistence and biodiversity. PMID:19193850

  7. Controlled on-chip stimulation of quantal catecholamine release from chromaffin cells using photolysis of caged Ca2+ on transparent indium-tin-oxide microchip electrodes.

    PubMed

    Chen, Xiaohui; Gao, Yuanfang; Hossain, Maruf; Gangopadhyay, Shubhra; Gillis, Kevin D

    2008-01-01

    Photorelease of caged Ca(2+) is a uniquely powerful tool to study the dynamics of Ca(2+)-triggered exocytosis from individual cells. Using photolithography and other microfabrication techniques, we have developed transparent microchip devices to enable photorelease of caged Ca(2+), together with electrochemical detection of quantal catecholamine secretion from individual cells or cell arrays as a step towards developing high-throughput experimental devices. A 100 nm thick transparent indium-tin-oxide (ITO) film was sputter-deposited onto glass coverslips, which were then patterned into 24 cell-sized working electrodes (approximately 20 microm by 20 microm). We loaded bovine chromaffin cells with acetoxymethyl (AM) ester derivatives of the Ca(2+) cage NP-EGTA and Ca(2+) indicator dye fura-4F, then transferred these cells onto the working ITO electrodes for amperometric recordings. Upon flash photorelease of caged Ca(2+), a uniform rise of [Ca(2+)](i) within the target cell leads to quantal release of oxidizable catecholamines measured amperometrically by the underlying ITO electrode. We observed a burst of amperometric spikes upon rapid elevation of [Ca(2+)](i) and a "priming" effect of sub-stimulatory [Ca(2+)](i) on the response of cells to subsequent [Ca(2+)](i) elevation, similar to previous reports using different techniques. We conclude that UV photolysis of caged Ca(2+) is a suitable stimulation technique for higher-throughput studies of Ca(2+)-dependent exocytosis on transparent electrochemical microelectrode arrays. PMID:18094774

  8. Controlled On-chip Stimulation of Quantal Catecholamine Release from Chromaffin Cells Using Photolysis of Caged Ca2+ on Transparent Indium-Tin-Oxide Microchip Electrodes

    PubMed Central

    Chen, Xiaohui; Gao, Yuanfang; Hossain, Maruf; Gangopadhyay, Shubhra; Gillis, Kevin D.

    2008-01-01

    Photorelease of caged Ca2+ is a uniquely powerful tool to study the dynamics of Ca2+-triggered exocytosis from individual cells. Using photolithography and other microfabrication techniques, we have developed transparent microchip devices to enable photorelease of caged Ca2+ together with electrochemical detection of quantal catecholamine secretion from individual cells or cell arrays as a step towards developing high-throughput experimental devices. A 100 nm - thick transparent Indium-Tin-Oxide (ITO) film was sputter-deposited onto glass coverslips, which were then patterned into 24 cell-sized working electrodes (∼20 μm by 20 μm). We loaded bovine chromaffin cells with acetoxymethyl (AM) ester derivatives of the Ca2+ cage NP-EGTA and Ca2+ indicator dye Fura-4F, then transferred these cells onto the working ITO electrodes for amperometric recordings. Upon flash photorelease of caged Ca2+, a uniform rise of [Ca2+]i within the target cell leads to quantal release of oxidizable catecholamines measured amperometrically by the underlying ITO electrode. We observed a burst of amperometric spikes upon rapid elevation of [Ca2+]i and a “priming” effect of sub-stimulatory [Ca2+]i on the response of cells to subsequent [Ca2+]i elevation, similar to previous reports using different techniques. We conclude that UV photolysis of caged Ca2+ is a suitable stimulation technique for higher-throughput studies of Ca2+-dependent exocytosis on transparent electrochemical microelectrode arrays. PMID:18094774

  9. Increased InAs quantum dot size and density using bismuth as a surfactant

    SciTech Connect

    Dasika, Vaishno D.; Krivoy, E. M.; Nair, H. P.; Maddox, S. J.; Park, K. W.; Yu, E. T.; Bank, S. R.; Jung, D.; Lee, M. L.

    2014-12-22

    We have investigated the growth of self-assembled InAs quantum dots using bismuth as a surfactant to control the dot size and density. We find that the bismuth surfactant increases the quantum dot density, size, and uniformity, enabling the extension of the emission wavelength with increasing InAs deposition without a concomitant reduction in dot density. We show that these effects are due to bismuth acting as a reactive surfactant to kinetically suppress the surface adatom mobility. This mechanism for controlling quantum dot density and size has the potential to extend the operating wavelength and enhance the performance of various optoelectronic devices.

  10. Increased CPC batch size study for Tank 42 sludge in the Defense Waste Processing Facility

    SciTech Connect

    Daniel, W.E.

    2000-01-06

    A series of experiments have been completed at TNX for the sludge-only REDOX adjusted flowsheet using Tank 42 sludge simulant in response to the Technical Task Request HLW/DWPT/TTR-980013 to increase CPC batch sizes. By increasing the initial SRAT batch size, a melter feed batch at greater waste solids concentration can be prepared and thus increase melter output per batch by about one canister. The increased throughput would allow DWPF to dispose of more waste in a given time period thus shortening the overall campaign.

  11. Thermal and quantal isospin and spin fluctuations in heavy ion reactions

    SciTech Connect

    Moretto, L.G.

    1980-01-01

    The isobaric charge distributions are discussed in terms of quantal and classical isospin fluctuations. The roles of mass asymmetry and of the higher giant isovector modes are treated within the framework of a cylinder model that is worked out exactly. Spin fluctuations are considered first in terms of quantal fluctuations in a cylinder model and second in terms of thermal fluctuations in a two-sphere model. The results are applied to the calculation of in- and out-of-plane angular distributions for sequential fission, alpha and gamma decay. Analytical expressions are obtained for the angular distributions. The theoretical predictions are compared with experimental results for sequential fission, alpha, and gamma angular distributions. 23 figures.

  12. Demyelination increases axonal stationary mitochondrial size and the speed of axonal mitochondrial transport

    PubMed Central

    Kiryu-Seo, Sumiko; Ohno, Nobuhiko; Kidd, Grahame J.; Komuro, Hitoshi; Trapp, Bruce D.

    2010-01-01

    Axonal degeneration contributes to permanent neurological disability in inherited and acquired diseases of myelin. Mitochondrial dysfunction has been proposed as a major contributor to this axonal degeneration. It remains to be determined, however, if myelination, demyelination or remyelination alter the size and distribution of axonal mitochondrial stationary sites or the rates of axonal mitochondrial transport. Using live myelinated rat dorsal root ganglion (DRG) cultures, we investigated whether myelination and lysolecithin-induced demyelination affect axonal mitochondria. Myelination increased the size of axonal stationary mitochondrial sites by 2.3 fold. Following demyelination, the size of axonal stationary mitochondrial sites was increased by an additional 2.2 fold and the transport velocity of motile mitochondria was increased by 47%. These measures returned to the levels of myelinated axons following remyelination. Demyelination induced activating transcription factor (ATF) 3 in DRG neurons. Knockdown of neuronal ATF3 by shRNA abolished the demyelination-induced increase in axonal mitochondrial transport and increased nitrotyrosine immunoreactivity in axonal mitochondria, suggesting that neuronal ATF3 expression and increased mitochondrial transport protect demyelinated axons from oxidative damage. In response to insufficient ATP production, demyelinated axons increase the size of stationary mitochondrial sites and thereby balance ATP production with the increased energy needs of nerve conduction. PMID:20463228

  13. Electroporation followed by electrochemical measurement of quantal transmitter release from single cells using a patterned microelectrode

    PubMed Central

    Ghosh, Jaya; Liu, Xin; Gillis, Kevin D.

    2013-01-01

    An electrochemical microelectrode located immediately adjacent to a single neuroendocrine cell can record spikes of amperometric current that result from exocytosis of oxidizable transmitter from individual vesicles, i.e., quantal exocytosis. Here, we report the development of an efficient method where the same electrochemical microelectrode is used to electropermeabilize an adjacent chromaffin cell and then measure the consequent quantal catecholamine release using amperometry. Trains of voltage pulses, 5–7 V in amplitude and 0.1–0.2 ms in duration, were used to reliably trigger release from cells using gold electrodes. Amperometric spikes induced by electropermeabilization had similar areas, peak heights and durations as amperometric spikes elicited by depolarizing high K+ solutions, therefore release occurs from individual secretory granules. Uptake of trypan blue stain into cells demonstrated that the plasma membrane is permeabilized by the voltage stimulus. Voltage pulses did not degrade the electrochemical sensitivity of the electrodes assayed using a test analyte. Surprisingly, robust quantal release was elicited upon electroporation in the absence of Ca2+ in the bath solution (0 Ca2+/5 mM EGTA). In contrast, electropermeabilization-induced transmitter release required Cl− in the bath solution in that bracketed experiments demonstrated a steep dependence of the rate of electropermeabilization-induced transmitter release on [Cl−] between 2 and 32 mM. Using the same electrochemical electrode to electroporate and record quantal release of catecholamines from an individual chromaffin cell allows precise timing of the stimulus, stimulation of a single cell at a time, and can be used to load membrane-impermeant substances into a cell. PMID:23598689

  14. A new diamond biosensor with integrated graphitic microchannels for detecting quantal exocytic events from chromaffin cells.

    PubMed

    Picollo, Federico; Gosso, Sara; Vittone, Ettore; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2013-09-14

    An MeV ion-microbeam lithographic technique can be successfully employed for the fabrication of an all-carbon miniaturized cellular biosensor based on graphitic microchannels embedded in a single-crystal diamond matrix. The device is functionally characterized for the in vitro recording of quantal exocytic events from single chromaffin cells, with high sensitivity and signal-to-noise ratio, opening promising perspectives for the realization of monolithic all-carbon cellular biosensors. PMID:23847004

  15. Evolution of ASPM is associated with both increases and decreases in brain size in primates.

    PubMed

    Montgomery, Stephen H; Mundy, Nicholas I

    2012-03-01

    A fundamental trend during primate evolution has been the expansion of brain size. However, this trend was reversed in the Callitrichidae (marmosets and tamarins), which have secondarily evolved smaller brains associated with a reduction in body size. The recent pursuit of the genetic basis of brain size evolution has largely focused on episodes of brain expansion, but new insights may be gained by investigating episodes of brain size reduction. Previous results suggest two genes (ASPM and CDK5RAP2) associated with microcephaly, a human neurodevelopmental disorder, may have an evolutionary function in primate brain expansion. Here we use new sequences encoding key functional domains from 12 species of callitrichids to show that positive selection has acted on ASPM across callitrichid evolution and the rate of ASPM evolution is significantly negatively correlated with callitrichid brain size, whereas the evolution of CDK5RAP2 shows no correlation with brain size. Our findings strongly suggest that ASPM has a previously unsuspected role in the evolution of small brains in primates. ASPM is therefore intimately linked to both evolutionary increases and decreases in brain size in anthropoids and is a key target for natural selection acting on brain size. PMID:22380452

  16. Diversification Rates Increase With Population Size and Resource Concentration in an Unstructured Habitat

    PubMed Central

    Stevens, M. H. H.; Sanchez, M.; Lee, J.; Finkel, S. E.

    2007-01-01

    Understanding the mechanisms controlling the generation and maintenance of biodiversity provides some of the planet's greatest and most pressing challenges. Variation in resource concentration, which varies widely at multiple scales, may cause biodiversity to increase, decrease, or exhibit a unimodal response and underlying mechanisms remain obscure. We established experimental cultures of long-term stationary phase (LTSP) Escherichia coli to test whether per capita heterozygosity varies with resource concentration, and, if so, whether population sizes associated with different resource concentrations contributed to these patterns. Our results provide the clearest example to date of increasing per capita heterozygosity with increasing resource concentration. Further, our experimental manipulations of population size, independent of resource concentration, provide the first unequivocal evidence that population size is one of the underlying factors controlling per capita heterozygosity along such resource gradients. Specifically, we show that cultures with higher maximum population sizes, associated with higher resource concentrations, have higher per capita heterozygosity. These experiments provide the first experimental evidence for an underappreciated factor controlling biodiversity along resource gradients—population size. This direct evidence of population size influencing diversification rates has implications for regional and global scale patterns of biodiversity. PMID:18073429

  17. Increases in plasma pool size of lipoprotein components in copper-deficient hamsters

    SciTech Connect

    Al-Othman, A.A.; Rosenstein, F.; Lei, K.Y. )

    1991-03-15

    Twenty-four male Golden Syrian hamsters, were randomly assigned to 2 dietary copper (Cu) treatments; deficient and adequate. Reductions in weight gain, hematocrit and liver Cu as well as increases in heart weight and plasma volume were observed in CD hamsters after 7 weeks of treatment. Plasma very low (VLDL), low (LDL) and high (HDL) density lipoproteins were isolated by ultracentrifugation and Sepharose column chromatography. The percentage of total plasma cholesterol carried by LDL was increased from 20 to 24% but was reduced from 71 to 68% for HDL as a result of Cu deficiency. In LDL the % composition of triglycerides (TG) and phospholipids (PL) was increased by 25% but that of cholesterol was reduced by 13%. The % composition of protein was reduced 24% but that of TG was increased 18% in VLDL by Cu deficiency. Since plasma volume was increased 50% in CD hamsters, the data were expressed as the amount present in the plasma pool corrected for body weight. With the exceptions of smaller increased in VLDL protein and PL as well as the more than threefold increases in LDL TG and PL plasma pool size, the pool size for the rest of the lipoprotein components were increased about twofold in CD hamsters. The lipoprotein data further indicate that Cu deficiency increased the particle number of VLDL, LDL and HDL but enlarged the size of only VLDL and LDL.

  18. Numerical Model to Characterize the Size Increase of Combination Drug and Hygroscopic Excipient Nanoparticle Aerosols

    PubMed Central

    Longest, P. Worth; Hindle, Michael

    2011-01-01

    Enhanced excipient growth is a newly proposed respiratory delivery strategy in which submicrometer or nanometer particles composed of a drug and hygroscopic excipient are delivered to the airways in order to minimize extrathoracic depositional losses and maximize lung retention. The objective of this study was to develop a validated mathematical model of aerosol size increase for hygroscopic excipients and combination excipient-drug particles and to apply this model to characterize growth under typical respiratory conditions. Compared with in vitro experiments, the droplet growth model accurately predicted the size increase of single component and combination drug and excipient particles. For typical respiratory drug delivery conditions, the model showed that droplet size increase could be effectively correlated with the product of a newly defined hygroscopic parameter and initial volume fractions of the drug and excipient in the particle. A series of growth correlations was then developed that successively included the effects of initial drug and excipient mass loadings, initial aerosol size, and aerosol number concentration. Considering EEG delivery, large diameter growth ratios (2.1–4.6) were observed for a range of hygroscopic excipients combined with both hygroscopic and non-hygroscopic drugs. These diameter growth ratios were achieved at excipient mass loadings of 50% and below and at realistic aerosol number concentrations. The developed correlations were then used for specifying the appropriate initial mass loadings of engineered insulin nanoparticles in order to achieve a predetermined size increase while maximizing drug payload and minimizing the amount of hygroscopic excipient. PMID:21804683

  19. Increasing the size of portion options affects intake but not portion selection at a meal.

    PubMed

    Zuraikat, Faris M; Roe, Liane S; Privitera, Gregory J; Rolls, Barbara J

    2016-03-01

    In an environment with large portion sizes, allowing consumers more control over their portion selection could moderate the effects on energy intake. We tested whether having subjects choose a portion from several options influenced the amount selected or consumed when all portion sizes were systematically increased. In a crossover design, 24 women and 26 men ate lunch in the lab once a week for 3 weeks. At each meal, subjects chose a portion of macaroni and cheese from a set of 3 portion options and consumed it ad libitum. Across 3 conditions, portion sizes in the set were increased; the order of the conditions was counterbalanced across subjects. For women the portion sets by weight (g) were 300/375/450, 375/450/525, and 450/525/600; for men the portions were 33% larger. The results showed that increasing the size of available portions did not significantly affect the relative size selected; across all portion sets, subjects chose the smallest available portion at 59% of meals, the medium at 27%, and the largest at 15%. The size of portions offered did, however, influence meal intake (P < 0.0001). Mean intake (±SEM) was 16% greater when the largest set was offered (661 ± 34 kcal) than when the medium and smallest sets were offered (both 568 ± 18 kcal). These results suggest that portions are selected in relation to the other available options, and confirm the robust effect of portion size on intake. Although presenting a choice of portions can allow selection of smaller amounts, the sizes offered are a critical determinant of energy intake. Thus, the availability of choices could help to moderate intake if the portions offered are within an appropriate range for energy needs. PMID:26721718

  20. Prey size structure diminishes cascading effects by increasing interference competition and predation among prey.

    PubMed

    Geraldii, Nathan R

    2015-09-01

    The size of an organism can change by orders of magnitude during its lifespan. Size can determine whether an individual consumes, is consumed, competes, or avoids individuals of the same or different species. Two complementary mesocosm experiments with a tri-trophic food chain (top predator, toadfish, Opsanus tau; intermediate prey, mud crab, family Xanthidae; basal resource, oyster, Crassostrea virginica) were conducted to measure how the size of both the top predator and the intermediate prey affects consumptive and behavioral interactions in trophic cascades. In the first experiment, I systematically varied the sizes of predators and prey, respectively. The amount of crab biomass consumed was dependent on crab size and not toadfish size, but the effect of crab size did not cascade to alter oyster survival. Increased oyster survival from crab interference competition in the absence of toadfish was similar to oyster survival,from predator-avoidance behavior in the presence of a toadfish. When all crab size classes were present, crab mortality was similar in the presence and absence of toadfish, highlighting the importance of intraguild predation in food-web dynamics. The second experiment separated crab mortality by other crabs from crab mortality by predatory toadfish and found that crab mortality generally switched from intra- to interguild predation when a toadfish was present. In addition, field surveys indicated mud crab abundance and size was primarily influenced by mud crab recruitment, but not by toadfish abundance, which supports our experimental results that interactions among mud crabs have similar effects to predator-prey interactions. These findings indicate that changes in size or abundance of intermediate prey may be comparable to changes in top predator abundance in terms of trophic interactions and their transmission to lower levels, which suggests that certain types of relatively simple food chains can be resilient to the loss of higher trophic

  1. Increased Leaf Size: Different Means to an End1[W][OA

    PubMed Central

    Gonzalez, Nathalie; De Bodt, Stefanie; Sulpice, Ronan; Jikumaru, Yusuke; Chae, Eunyoung; Dhondt, Stijn; Van Daele, Twiggy; De Milde, Liesbeth; Weigel, Detlef; Kamiya, Yuji; Stitt, Mark; Beemster, Gerrit T.S.; Inzé, Dirk

    2010-01-01

    The final size of plant organs, such as leaves, is tightly controlled by environmental and genetic factors that must spatially and temporally coordinate cell expansion and cell cycle activity. However, this regulation of organ growth is still poorly understood. The aim of this study is to gain more insight into the genetic control of leaf size in Arabidopsis (Arabidopsis thaliana) by performing a comparative analysis of transgenic lines that produce enlarged leaves under standardized environmental conditions. To this end, we selected five genes belonging to different functional classes that all positively affect leaf size when overexpressed: AVP1, GRF5, JAW, BRI1, and GA20OX1. We show that the increase in leaf area in these lines depended on leaf position and growth conditions and that all five lines affected leaf size differently; however, in all cases, an increase in cell number was, entirely or predominantly, responsible for the leaf size enlargement. By analyzing hormone levels, transcriptome, and metabolome, we provide deeper insight into the molecular basis of the growth phenotype for the individual lines. A comparative analysis between these data sets indicates that enhanced organ growth is governed by different, seemingly independent pathways. The analysis of transgenic lines simultaneously overexpressing two growth-enhancing genes further supports the concept that multiple pathways independently converge on organ size control in Arabidopsis. PMID:20460583

  2. Splenic release of platelets contributes to increased circulating platelet size and inflammation after myocardial infarction.

    PubMed

    Gao, Xiao-Ming; Moore, Xiao-Lei; Liu, Yang; Wang, Xin-Yu; Han, Li-Ping; Su, Yidan; Tsai, Alan; Xu, Qi; Zhang, Ming; Lambert, Gavin W; Kiriazis, Helen; Gao, Wei; Dart, Anthony M; Du, Xiao-Jun

    2016-07-01

    Acute myocardial infarction (AMI) is characterized by a rapid increase in circulating platelet size but the mechanism for this is unclear. Large platelets are hyperactive and associated with adverse clinical outcomes. We determined mean platelet volume (MPV) and platelet-monocyte conjugation (PMC) using blood samples from patients, and blood and the spleen from mice with AMI. We further measured changes in platelet size, PMC, cardiac and splenic contents of platelets and leucocyte infiltration into the mouse heart. In AMI patients, circulating MPV and PMC increased at 1-3 h post-MI and MPV returned to reference levels within 24 h after admission. In mice with MI, increases in platelet size and PMC became evident within 12 h and were sustained up to 72 h. Splenic platelets are bigger than circulating platelets in normal or infarct mice. At 24 h post-MI, splenic platelet storage was halved whereas cardiac platelets increased by 4-fold. Splenectomy attenuated all changes observed in the blood, reduced leucocyte and platelet accumulation in the infarct myocardium, limited infarct size and alleviated cardiac dilatation and dysfunction. AMI-induced elevated circulating levels of adenosine diphosphate and catecholamines in both human and the mouse, which may trigger splenic platelet release. Pharmacological inhibition of angiotensin-converting enzyme, β1-adrenergic receptor or platelet P2Y12 receptor reduced platelet abundance in the murine infarct myocardium albeit having diverse effects on platelet size and PMC. In conclusion, AMI evokes release of splenic platelets, which contributes to the increase in platelet size and PMC and facilitates myocardial accumulation of platelets and leucocytes, thereby promoting post-infarct inflammation. PMID:27129192

  3. Visual acuity and sensitivity increase allometrically with body size in butterflies.

    PubMed

    Rutowski, R L; Gislén, Lars; Warrant, Eric J

    2009-03-01

    In insects, the surface area of the compound eye increases with body size both within and between species with only a slight negative allometry. This increase in surface area permits changes in eye structure that affect the eye's acuity and sensitivity, two features of eye performance that cannot be simultaneously maximized. Hence, as eye size varies within a lineage, so will the compromises between features that maximize acuity and those that maximize sensitivity. We examined these compromises in four species of nymphalid butterflies that varied in body mass over almost two orders of magnitude. The largest of these species was crepuscular and so additionally may indicate the potential effect of life style on eye structure. Across these species, as body size increased, facet diameters increased while interommatidial angles decreased. Finally, the eye parameter was fairly constant across species except in the crepuscular species in which some notably large values were observed in the frontal visual field. Based on our measurements, large butterflies have more acute and more sensitive vision than smaller butterflies. However, full understanding of the behavioral implications of this relationship awaits information on the temporal resolution of their eyes because typical flight velocities also increase with body size. PMID:18809509

  4. Does increasing daylength control seasonal changes in clutch sizes of Northern Pintails (Anas acuta)?

    USGS Publications Warehouse

    Krapu, G.L.; Sargeant, G.A.; Perkins, A.E.H.

    2002-01-01

    We evaluated spatiotemporal variation in clutch sizes of Northern Pintails (pintails; Anas acuta) nesting in California (1985 to 1996), North Dakota (1982 to 1985), Saskatchewan (1982 to 1985) and Alaska (1991 to 1993) to determine whether seasonal declines in clutch size varied in ways that were consistent with a controlling influence of increasing day length. Pintails began nesting in mid-March in California, mid-April in North Dakota and Saskatchewan, and mid-May in Alaska. Observed durations of nesting were 70 ?? 2.6 days (SE) in California, 60 ?? 6.3 days in North Dakota, 66 ?? 1.3 days in Saskatchewan, and 42 ?? 0.7 days in Alaska. Annual differences were the principal source of variation in mean clutch sizes (????Y2 = 0.15, SE = 0.049), which varied little among study locations (????A2 = 0.002, SE = 0.013). Predicted rates of seasonal decline in clutch sizes increased with latitude early in the nesting season, but declined as the nesting season progressed, except in California. Rates of decline in clutch sizes thus were not directly related to rates of increase in day length. Predicted declines in numbers of eggs per clutch over the nesting season were similar for all four locations (range, 3.05-3.12) despite wide variation in durations of nesting. Evidence suggests that reduced nutrient availability during nesting contributes to a higher rate of decline in clutch sizes in Alaska than in temperate regions. Pintails that nest early lay large initial clutches, but thereafter clutch sizes decline rapidly and breeding terminates early. This reproductive strategy is adaptive because young that hatch earliest exhibit the highest survival rates; however, the conversion of grassland to cropland on the primary prairie breeding grounds has reduced hatching rates of clutches laid early in the nesting season. Under these conditions, the limited capacity to renest in late spring on their prairie breeding grounds probably has contributed to Pintail population declines.

  5. Potential problems with increasing serving sizes on the Nutrition Facts label.

    PubMed

    Dallas, Steven K; Liu, Peggy J; Ubel, Peter A

    2015-12-01

    The United States Food and Drug Administration recently announced that the serving sizes on the Nutrition Facts labels for many products will be increased, but the effect of these increases remains unclear. The present research examined consumers' interpretation of the meaning of serving size information (study 1) and tested whether exposing consumers to the increased serving sizes of the proposed Nutrition Facts label leads consumers to serve and purchase more food for themselves and others (studies 2-4). Study 1 (N = 101; 44.7% female) tested what consumers believe the serving sizes on Nutrition Facts labels refer to, and the majority of participants (over 78%) incorrectly believed that the serving sizes refer to how much food can or should be consumed in one sitting as part of a healthy diet. Study 2 (N = 51; 41.2% female) tested how exposure to the current versus proposed Nutrition Facts label influences the amount of food that consumers serve themselves, and studies 3 (N = 60; 46.7% female) and 4 (N = 61; 48.2% female) assessed how exposure to the current versus proposed label influences the amount of food that people serve and purchase for others. In studies 2-4, the proposed label (vs. the current label) led consumers to serve themselves 41% more cookies (study 2); serve 27% more cheese crackers to another person (study 3); and buy 43% more lasagnas for others and divide a lasagna into 22% larger slices (study 4). The results suggest that the proposed Nutrition Facts label's increased serving sizes may lead people who use this information as a reference to serve more food to themselves and others. PMID:26278876

  6. Costs and benefits of increased weapon size differ between sexes of the slender crayfish, Cherax dispar.

    PubMed

    Wilson, Robbie S; James, Rob S; Bywater, Candice; Seebacher, Frank

    2009-03-01

    Unreliable signals of weapon strength are considered to be problematic for signalling theory and reliable signals are predicted to be the dominant form of signalling among conspecifics in nature. Previous studies have shown that males of the Australian freshwater crayfish (Cherax dispar) routinely use unreliable signals of strength whereas females use reliable signals of weapon strength. In this study, we examined the performance benefits of increased weapon (chela) size for both males and females of C. dispar. In addition, we investigated the possibility of functional trade-offs in weapon size by assessing the relationship between chela size and maximum escape swimming performance. We found males possessed larger and stronger chelae than females and the variance in chela force was greater for males than females. By contrast, females possessed greater absolute and body length-specific escape swimming speeds than males. Swimming speed was also negatively correlated with chela size for males but not females, suggesting that a functional trade-off exists for males only. Decreases in swimming speed with increases in weapon size suggest there could be important fitness costs associated with larger chelae. Larger weaponry of males may then act as a handicap ensuring large chelae are reliable signals of quality. PMID:19252002

  7. Floral herbivory increases with inflorescence size and local plant density in Digitalis purpurea

    NASA Astrophysics Data System (ADS)

    Sletvold, Nina; Grindeland, John M.

    2008-07-01

    Insect herbivores search for their host plants in heterogeneous environments, and the efficiency of host location may be influenced by plant architecture and abundance. In this study, we ask how plant and habitat characteristics traditionally thought to attract pollinators are related to attack rates by floral herbivores. Patterns of floral herbivory by the moth larva Eupithecia pulchellata were studied in relation to inflorescence size and local plant density in two years in a natural population of the facultative biennial Digitalis purpurea. Overall levels of herbivory were low, 84% of the infested plants lost less than 10% of their flowers. Only 9% of the plants lost more than 20% of their flowers. Probability of herbivory at the plant level increased strongly with inflorescence height, and it was considerably higher in dense patches compared to sparse ones. There was no effect of local plant density on the functional relationship between inflorescence size and probability of herbivory. Both number and proportion of damaged flowers per plant increased with inflorescence height. The results suggest that E. pulchellata is attracted to dense patches and large individuals of D. purpurea, and that negative effects of herbivory increase with plant size. This implies diminishing returns for investment in more flowers in D. purpurea, and indicates that herbivory may select for smaller flowering size and flower number in this monocarpic species.

  8. The largest Last Supper: depictions of food portions and plate size increased over the millennium.

    PubMed

    Wansink, B; Wansink, C S

    2010-05-01

    Portion sizes of foods have been noticably increasing in recent years, but when did this trend begin? If art imitates life and if food portions have been generally increasing with time, we might expect this trend to be reflected in paintings that depict food. Perhaps the most commonly painted meal has been that of Jesus Christ's Last Supper, chronicled in the New Testament of the Bible. A CAD-CAM analysis of the relative food-to-head ratio in 52 representative paintings of the Last Supper showed that the relative sizes of the main dish (entree) (r=0.52, P=0.002), bread (r=0.30, P=0.04), and plates (r=0.46, P=0.02) have linearly increased over the past millennium. PMID:20308996

  9. Marine mixotrophy increases trophic transfer efficiency, mean organism size, and vertical carbon flux.

    PubMed

    Ward, Ben A; Follows, Michael J

    2016-03-15

    Mixotrophic plankton, which combine the uptake of inorganic resources and the ingestion of living prey, are ubiquitous in marine ecosystems, but their integrated biogeochemical impacts remain unclear. We address this issue by removing the strict distinction between phytoplankton and zooplankton from a global model of the marine plankton food web. This simplification allows the emergence of a realistic trophic network with increased fidelity to empirical estimates of plankton community structure and elemental stoichiometry, relative to a system in which autotrophy and heterotrophy are mutually exclusive. Mixotrophy enhances the transfer of biomass to larger sizes classes further up the food chain, leading to an approximately threefold increase in global mean organism size and an ∼35% increase in sinking carbon flux. PMID:26831076

  10. Density-functional errors in ionization potential with increasing system size

    NASA Astrophysics Data System (ADS)

    Whittleton, Sarah R.; Sosa Vazquez, Xochitl A.; Isborn, Christine M.; Johnson, Erin R.

    2015-05-01

    This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems.

  11. Density-functional errors in ionization potential with increasing system size

    SciTech Connect

    Whittleton, Sarah R.; Sosa Vazquez, Xochitl A.; Isborn, Christine M.; Johnson, Erin R.

    2015-05-14

    This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems.

  12. Induced polyploidy dramatically increases the size and alters the shape of fruit in Actinidia chinensis

    PubMed Central

    Wu, Jin-Hu; Ferguson, A. Ross; Murray, Brian G.; Jia, Yilin; Datson, Paul M.; Zhang, Jingli

    2012-01-01

    Background and Aims Some otherwise promising selections of Actinidia chinensis (kiwifruit) have fruit that are too small for successful commercialization. We have therefore made the first detailed study in diploid kiwifruit of the effects of chromosome doubling induced by colchicine on fruit size, shape and crop loading. Methods Flow cytometric analysis of young leaves and chromosome analysis of flower buds and root tips was used to confirm the stability of induced autotetraploids. Fruit weight, size and crop load were measured in the third year after planting in the field and for three consecutive years. DNA fingerprinting was used to confirm the origin of the material. Key Results There was a very significant increase in fruit size in induced autotetraploids of different genotypes of A. chinensis. With the commercially important diploid cultivar ‘Hort16A’, most regenerants, Type A plants, had fruit which were much the same shape as fruit of the diploid but, at the same fruit load, were much larger and heavier. Some regenerants, Type B plants, produced fruit similar to ‘fasciated’ fruit. Fruit of the autotetraploids induced from three female red-fleshed A. chinensis selections were also 50–60 % larger than fruit of their diploid progenitors. The main increase in fruit dimensions was in their diameters. These improved fruit characteristics were stable over several seasons. Conclusions Chromosome doubling has been shown to increase significantly fruit size in autotetraploid A. chinensis, highlighting the considerable potential of this technique to produce new cultivars with fruit of adequate size. Other variants with differently shaped fruit were also produced but the genetic basis of this variation remains to be elucidated. Autoploids of other Actinidia species with commercial potential may also show improved fruit characteristics, opening up many new possibilities for commercial development. PMID:21980192

  13. A simple means of increasing muscle size after spinal cord injury: a pilot study.

    PubMed

    Dudley, G A; Castro, M J; Rogers, S; Apple, D F

    1999-09-01

    This study tested that hypothesis that skeletal muscle within a year of spinal cord injury (SCI) would respond to intermittent high force loading by showing an increase in size. Three males about 46 weeks post clinically complete SCI underwent surface electrical stimulation of their left or right m. quadriceps femoris 2 days per week for 8 weeks to evoke 4 sets of ten isometric or dynamic actions each session. Conditioning increased average cross-sectional area of m. quadriceps femoris, assessed by magnetic resonance imaging, by 20+/-1% (p = 0.0103). This reversed 48 weeks of atrophy such that m. quadriceps femoris 54 weeks after SCI was the same size as when the patients were first studied 6 weeks after injury. The results suggest that skeletal muscle is remarkably responsive to intermittent, high force loading after almost one year of little if any contractile activity. PMID:10483812

  14. Portion size can be used strategically to increase vegetable consumption in adults123

    PubMed Central

    Roe, Liane S; Meengs, Jennifer S

    2010-01-01

    Background: An increase in the proportion of vegetables at meals could help achieve recommended vegetable intakes and facilitate weight management. Objective: We investigated the effects on food and energy intakes of varying the portion size and energy density of a vegetable that was added to a meal or substituted for other foods. Design: In 2 experiments with crossover designs, men and women were served a meal of a vegetable, grain, and meat. Across the meals, the vegetable was served in 3 portion sizes (180, 270, or 360 g) and 2 energy densities (0.8 or 0.4 kcal/g) by altering the type and amount of added fat. In the addition study (n = 49), as the vegetable portion was increased, amounts of the grain and meat were unchanged, whereas in the substitution study (n = 48), amounts of the grain and meat decreased equally. Results: An increase in the vegetable portion size resulted in greater vegetable consumption in both studies (mean ± SE: 60 ± 5 g; P < 0.0001). The addition of more of the vegetable did not significantly affect meal energy intake, whereas substitution of the vegetable for the grain and meat decreased meal energy intake (40 ± 10 kcal; P < 0.0001). A reduction in vegetable energy density decreased meal energy intake independent of portion size (55 ± 9 kcal; P < 0.0001). By combining substitution with a reduction in energy density, meal energy intake decreased by 14 ± 3%. Conclusions: Serving more vegetables, either by adding more or substituting them for other foods, is an effective strategy to increase vegetable intake at a meal. However, to moderate meal energy intake, vegetables should be low in energy density; furthermore, the substitution of vegetables for more energy-dense foods is more effective than simply adding extra vegetables. PMID:20147467

  15. Parallel cone bipolar pathways to a ganglion cell use different rates and amplitudes of quantal excitation.

    PubMed

    Freed, M A

    2000-06-01

    The cone signal reaches the cat's On-beta (X) ganglion cell via several parallel circuits (bipolar cell types b1, b2, and b3). These circuits might convey different regions of the cone's temporal bandwidth. To test this, I presented a step of light that elicited a transient depolarization followed by a sustained depolarization. The contribution of bipolar cells to these response components was isolated by blocking action potentials with tetrodotoxin and by blocking inhibitory synaptic potentials with bicuculline and strychnine. Stationary fluctuation analysis of the sustained depolarization gave the rate of quantal bombardment: approximately 5100 quanta sec(-1) for small central cells and approximately 45,000 quanta sec(-1) for large peripheral cells. Normalizing these rates for the vastly different numbers of bipolar synapses (150-370 per small cell vs 2000 per large cell), quantal rate was constant across the retina, approximately 22 quanta synapse(-1) sec(-1). Nonstationary fluctuation analysis gave the mean quantal EPSP amplitude: approximately 240 microV for the transient depolarization and 30 microV for the sustained depolarization. The b1 bipolar cell is known from noise analysis of the On-alpha ganglion cell to have a near-maximal sustained release of only approximately two quanta synapse(-1) sec(-1). This implies that the other bipolar types (b2 and b3) contribute many more quanta to the sustained depolarization (>/=46 synapse(-1) sec(-1)). Type b1 probably contributes large quanta to the transient depolarization. Thus, bipolar cell types b1 and b2/b3 apparently constitute parallel circuits that convey, respectively, high and low frequencies. PMID:10818130

  16. Wildfires increasing in size and frequency across the U.S. West

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-08-01

    Since 1984, wildfires have increased in size and frequency, correlating with higher drought severity across the western United States. Dennison et al. looked at remotely sensed data from the U.S. government's Monitoring Trends in Burn Severity project from the years 1984-2011, focusing on fires larger than 400 hectares in nine ecoregions that included mountains, plains, and deserts. The authors found that not only are wildfires becoming more frequent—by an estimated seven large fires per year—but they are also burning more total area, increasing by about 355 square kilometers per year.

  17. Automated Targeting of Cells to Electrochemical Electrodes Using a Surface Chemistry Approach for the Measurement of Quantal Exocytosis

    PubMed Central

    2010-01-01

    Here, we describe a method to fabricate a multichannel high-throughput microchip device for the measurement of quantal transmitter release from individual cells. Instead of bringing carbon-fiber electrodes to cells, the device uses a surface chemistry approach to bring cells to an array of electrochemical microelectrodes. The microelectrodes are small and cytophilic in order to promote adhesion of a single cell, whereas all other areas of the chip are covered with a thin cytophobic film to block cell attachement and facilitate the movement of cells to electrodes. This cytophobic film also insulates unused areas of the conductive film; thus, the alignment of cell docking sites to working electrodes is automatic. Amperometric spikes resulting from single-granule fusion events were recorded on the device and had amplitudes and kinetics similar to those measured using carbon-fiber microelectrodes. Use of this device will increase the pace of basic neuroscience research and may also find applications in drug discovery or validation. PMID:21113333

  18. A Bayesian approach to the analysis of quantal bioassay studies using nonparametric mixture models.

    PubMed

    Fronczyk, Kassandra; Kottas, Athanasios

    2014-03-01

    We develop a Bayesian nonparametric mixture modeling framework for quantal bioassay settings. The approach is built upon modeling dose-dependent response distributions. We adopt a structured nonparametric prior mixture model, which induces a monotonicity restriction for the dose-response curve. Particular emphasis is placed on the key risk assessment goal of calibration for the dose level that corresponds to a specified response. The proposed methodology yields flexible inference for the dose-response relationship as well as for other inferential objectives, as illustrated with two data sets from the literature. PMID:24354490

  19. Increased monolayer domain size and patterned growth of tungsten disulfide through controlling surface energy of substrates

    NASA Astrophysics Data System (ADS)

    Godin, Kyle; Kang, Kyungnam; Fu, Shichen; Yang, Eui-Hyeok

    2016-08-01

    We report a surface energy-controlled low-pressure chemical vapor deposition growth of WS2 monolayers on SiO2 using pre-growth oxygen plasma treatment of substrates, facilitating increased monolayer surface coverage and patterned growth without lithography. Oxygen plasma treatment of the substrate caused an increase in the average domain size of WS2 monolayers by 78%  ±  2% while having a slight reduction in nucleation density, which translates to increased monolayer surface coverage. This substrate effect on growth was exploited to grow patterned WS2 monolayers by patterned plasma treatment on patterned substrates and by patterned source material with resolutions less than 10 µm. Contact angle-based surface energy measurements revealed a dramatic increase in polar surface energy. A growth model was proposed with lowered activation energies for growth and increased surface diffusion length consistent with the range of results observed. WS2 samples grown with and without oxygen plasma were similar high quality monolayers verified through transmission electron microscopy, selected area electron diffraction, atomic force microscopy, Raman, and photoluminescence measurements. This technique enables the production of large-grain size, patterned WS2 without a post-growth lithography process, thereby providing clean surfaces for device applications.

  20. Increase of chronic low back pain prevalence in a medium-sized city of southern Brazil

    PubMed Central

    2013-01-01

    Background Chronic low back pain (CLBP) is a highly disabling morbidity with high social, economic and individual effects. Demographic, occupational and behavioral changes that took place in Brazil over the last decade are related with an increasing burden of chronic conditions. Despite these changes, comparison studies on CLBP prevalence and associated factors, over time are scarce in the literature in general, and unknown in Brazil. The present study compared the CLBP prevalence in a medium sized city in Brazil between the years 2002 and 2010 and examined factors associated with prevalence in 2010. Methods Two cross-sectional studies with similar methodology were conducted in a medium-sized city in southern Brazil, in 2002 and 2010. 3182 individuals were interviewed in the first study and 2732 in the second one, all adults aged twenty years or more. Those who reported pain for seven weeks or more in the last three months in the lumbar region where considered cases of CLBP. Results The CLBP prevalence increased from 4.2% to 9.6% in 8 years. In most of the studied subgroups the CLBP prevalence has at least doubled and the increase was even larger among younger individuals with more years of education and higher economic status. Conclusions Increase in CLBP prevalence is worrisome because it is a condition responsible for substantial social impact, besides being an important source of demand for health services. PMID:23634830

  1. Acute sleep deprivation increases portion size and affects food choice in young men.

    PubMed

    Hogenkamp, Pleunie S; Nilsson, Emil; Nilsson, Victor C; Chapman, Colin D; Vogel, Heike; Lundberg, Lina S; Zarei, Sanaz; Cedernaes, Jonathan; Rångtell, Frida H; Broman, Jan-Erik; Dickson, Suzanne L; Brunstrom, Jeffrey M; Benedict, Christian; Schiöth, Helgi B

    2013-09-01

    Acute sleep loss increases food intake in adults. However, little is known about the influence of acute sleep loss on portion size choice, and whether this depends on both hunger state and the type of food (snack or meal item) offered to an individual. The aim of the current study was to compare portion size choice after a night of sleep and a period of nocturnal wakefulness (a condition experienced by night-shift workers, e.g. physicians and nurses). Sixteen men (age: 23 ± 0.9 years, BMI: 23.6 ± 0.6 kg/m(2)) participated in a randomized within-subject design with two conditions, 8-h of sleep and total sleep deprivation (TSD). In the morning following sleep interventions, portion size, comprising meal and snack items, was measured using a computer-based task, in both fasted and sated state. In addition, hunger as well as plasma levels of ghrelin were measured. In the morning after TSD, subjects had increased plasma ghrelin levels (13%, p=0.04), and chose larger portions (14%, p=0.02), irrespective of the type of food, as compared to the sleep condition. Self-reported hunger was also enhanced (p<0.01). Following breakfast, sleep-deprived subjects chose larger portions of snacks (16%, p=0.02), whereas the selection of meal items did not differ between the sleep interventions (6%, p=0.13). Our results suggest that overeating in the morning after sleep loss is driven by both homeostatic and hedonic factors. Further, they show that portion size choice after sleep loss depend on both an individual's hunger status, and the type of food offered. PMID:23428257

  2. Oxidative Damage Does Not Occur in Striped Hamsters Raising Natural and Experimentally Increased Litter Size.

    PubMed

    Zhao, Xiao-Ya; Zhang, Ji-Ying; Cao, Jing; Zhao, Zhi-Jun

    2015-01-01

    Life-history theory assumes that animals can balance the allocation of limited energy or resources to the competing demands of growth, reproduction and somatic maintenance, while consequently maximizing their fitness. However, somatic damage caused by oxidative stress in reproductive female animals is species-specific or is tissue dependent. In the present study, several markers of oxidative stress (hydrogen peroxide, H2O2 and malonadialdehyde, MDA) and antioxidant (catalase, CAT and total antioxidant capacity, T-AOC) were examined in striped hamsters during different stages of reproduction with experimentally manipulated litter size. Energy intake, resting metabolic rate (RMR), and mRNA expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and UCP3 in skeletal muscle were also examined. H2O2 and MDA levels did not change in BAT and liver, although they significantly decreased in skeletal muscle in the lactating hamsters compared to the non-reproductive group. However, H2O2 levels in the brain were significantly higher in lactating hamsters than non-reproductive controls. Experimentally increasing litter size did not cause oxidative stress in BAT, liver and skeletal muscle, but significantly elevated H2O2 levels in the brain. CAT activity of liver decreased, but CAT and T-AOC activity of BAT, skeletal muscle and the brain did not change in lactating hamsters compared to non-reproductive controls. Both antioxidants did not change with the experimentally increasing litter size. RMR significantly increased, but BAT UCP1 mRNA expression decreased with the experimentally increased litter size, suggesting that it was against simple positive links between metabolic rate, UCP1 expression and free radicals levels. It may suggest that the cost of reproduction has negligible effect on oxidative stress or even attenuates oxidative stress in some active tissues in an extensive range of animal species. But the increasing reproductive effort may cause oxidative

  3. Quantal rotation and its coupling to intrinsic motion in nuclei

    NASA Astrophysics Data System (ADS)

    Nakatsukasa, Takashi; Matsuyanagi, Kenichi; Matsuzaki, Masayuki; Shimizu, Yoshifumi R.

    2016-07-01

    Symmetry breaking is an important concept in nuclear physics and other fields of physics. Self-consistent coupling between the mean-field potential and the single-particle motion is a key ingredient in the unified model of Bohr and Mottelson, which could lead to a deformed nucleus as a consequence of spontaneous breaking of the rotational symmetry. Some remarks on the finite-size quantum effects are given. In finite nuclei, the deformation inevitably introduces the rotation as a symmetry-restoring collective motion (Anderson–Nambu–Goldstone mode), and the rotation affects the intrinsic motion. In order to investigate the interplay between the rotational and intrinsic motions in a variety of collective phenomena, we use the cranking prescription together with the quasiparticle random phase approximation (QRPA). At low spin, the coupling effect can be seen in the generalized intensity relation. A feasible quantization of the cranking model is presented, which provides a microscopic approach to the higher-order intensity relation. At high spin, the semiclassical cranking prescription works well. We discuss properties of collective vibrational motions under rapid rotation and/or large deformation. The superdeformed shell structure plays a key role in emergence of a new soft mode which could lead to instability toward the {K}π ={1}- octupole shape. A wobbling mode of excitation, which is a clear signature of the triaxiality, is discussed in terms of a microscopic point of view. A crucial role played by the quasiparticle alignment is presented.

  4. An analysis of increasing the size of the strategic petroleum reserve to one billion barrels

    SciTech Connect

    Not Available

    1990-01-01

    The Department of Energy's Office of Energy Emergency Policy and Evaluation requested that the Energy Information Administration complete an analysis of the proposed expansion in the Strategic Petroleum Reserve (SPR) from its currently planned size of 750 million barrels to 1000 million barrels. Because the SPR contains only 580 million barrels at this point in time, the benefits and costs of increasing the SPR from 600 to 750 million barrels were also estimated. This report documents the assumptions, methodology, and results of the analysis. 17 figs., 15 tabs.

  5. Developmental mortality increases sex-ratio bias of a size-dimorphic bark beetle

    PubMed Central

    Lachowsky, Leanna E; Reid, Mary L

    2014-01-01

    1. Given sexual size dimorphism, differential mortality owing to body size can lead to sex-biased mortality, proximately biasing sex ratios. This mechanism may apply to mountain pine beetles, Dendroctonus ponderosae Hopkins, which typically have female-biased adult populations (2 : 1) with females larger than males. Smaller males could be more susceptible to stresses than larger females as developing beetles overwinter and populations experience high mortality. 2. Survival of naturally-established mountain pine beetles during the juvenile stage and the resulting adult sex ratios and body sizes (volume) were studied. Three treatments were applied to vary survival in logs cut from trees containing broods of mountain pine beetles. Logs were removed from the forest either in early winter, or in spring after overwintering below snow or after overwintering above snow. Upon removal, logs were placed at room temperature to allow beetles to complete development under similar conditions. 3. Compared with beetles from logs removed in early winter, mortality was higher and the sex ratio was more female-biased in overwintering logs. The bias increased with overwinter mortality. However, sex ratios were female-biased even in early winter, so additional mechanisms, other than overwintering mortality, contributed to the sex-ratio bias. Body volume varied little relative to sex-biased mortality, suggesting other size-independent causes of male-biased mortality. 4. Overwintering mortality is considered a major determinant of mountain pine beetle population dynamics. The disproportionate survival of females, who initiate colonisation of live pine trees, may affect population dynamics in ways that have not been previously considered. PMID:25400320

  6. Competitive helping increases with the size of biological markets and invades defection.

    PubMed

    Barclay, Pat

    2011-07-21

    Cooperation between unrelated individuals remains a puzzle in evolutionary biology. Recent work indicates that partner choice can select for high levels of helping. More generally, helping can be seen as but one strategy used to compete for partners within a broader biological market, yet giving within such markets has received little mathematical investigation. In the present model, individuals help others to attract attention from them and thus receive a larger share of any help actively or passively provided by those others. The evolutionarily stable level of helping increases with the size of the biological market and the degree of partner choice. Furthermore, if individuals passively produce some no-cost help to partners, competitive helping can then invade populations of non-helpers because helpers directly benefit from increasing their access to potential partners. This framework of competitive helping demonstrates how high helping can be achieved and why different populations may differ in helping levels. PMID:21550351

  7. Hemodynamic-Morphological Discriminant Models for Intracranial Aneurysm Rupture Remain Stable with Increasing Sample Size

    PubMed Central

    Xiang, Jianping; Yu, Jihnhee; Snyder, Kenneth V.; Levy, Elad I.; Siddiqui, Adnan H.; Meng, Hui

    2016-01-01

    Background We previously established three logistic regression models for discriminating intracranial aneurysm rupture status based on morphological and hemodynamic analysis of 119 aneurysms (Stroke. 2011;42:144–152). In this study we tested if these models would remain stable with increasing sample size and investigated sample sizes required for various confidence levels. Methods We augmented our previous dataset of 119 aneurysms into a new dataset of 204 samples by collecting additional 85 consecutive aneurysms, on which we performed flow simulation and calculated morphological and hemodynamic parameters as done previously. We performed univariate significance tests of these parameters, and on the significant parameters we performed multivariate logistic regression. The new regression models were compared against the original models. Receiver operating characteristics analysis was applied to compare the performance of regression models. Furthermore, we performed regression analysis based on bootstrapping resampling statistical simulations to explore how many aneurysm cases were required to generate stable models. Results Univariate tests of the 204 aneurysms generated an identical list of significant morphological and hemodynamic parameters as previously from analysis of 119 cases. Furthermore, multivariate regression analysis produced three parsimonious predictive models that were almost identical to the previous ones; with model coefficients that had narrower confidence intervals than the original ones. Bootstrapping showed that 10%, 5%, 2%, and 1% convergence levels of confidence interval required 120, 200, 500, and 900 aneurysms, respectively. Conclusions Our original hemodynamic-morphological rupture prediction models are stable and improve with increasing sample size. Results from resampling statistical simulations provide guidance for designing future large multi-population studies. PMID:25488922

  8. [Characteristics of pedigree cat breeding in the Netherlands: breeds, population increase and litter size].

    PubMed

    Gerrits, P O; Huisman, T; Knol, B W

    1999-03-01

    A survey of the Dutch Cat Fancy was carried out to determine reproductive, patterns of pedigree cats. The data of the present study were obtained by questioning the pedigree registers of the cat clubs participating in the foundation 'Overleg Platform van de Nederlandse Cat Fancy'. The Dutch Cat Fancy registers 34 different cat breeds. From 1992 up to 1996 a total of 25.985 litters were registered. Over this period the number of litters increased from 4989 to 5313. Litters from Longhair and Exotic Shorthair cats comprised the biggest group and accounted for 55% of the total number of litters. However, over this period, the number of Longhair and Exotic Shorthair litters decreased by 9%. Litters from British Shorthair, Birman, Maine Coon and Norwegian Forrest Cat increased in number as did litters from small breeds such as Ragdoll, Bengal and Sphynx. Litters from Abyssinian, Siamese, Oriental Shorthair cats remained relatively the same. The average litter size of the total cat population, based on pedigree certificates, was calculated at 3.3 kittens per litter. For different breeds litter size varied from 2.7 (Longhair and Exotic Shorthair) to 4.3 (Burmese and Maine Coon). Taking into account an average age of 14 years, the total Dutch pedigree cat population was estimated at 240,000 viz. about 10% of the total cat population. PMID:10084198

  9. Increasing the size of an aromatic helical foldamer cavity by strand intercalation.

    PubMed

    Singleton, Michael L; Pirotte, Geert; Kauffmann, Brice; Ferrand, Yann; Huc, Ivan

    2014-11-24

    The postsynthetic modulation of capsules based on helical aromatic oligoamide foldamers would be a powerful approach for controlling their receptor properties without altering the initial monomer sequences. With the goal of developing a method to increase the size of a cavity within a helix, a single-helical foldamer capsule was synthesized with a wide-diameter central segment that was designed to intercalate with a second shorter helical strand. Despite the formation of stable double-helical homodimers (K(dim)>10(7) M(-1)) by the shorter strand, when it was mixed with the single-helical capsule sequence, a cross-hybridized double helix was formed with K(a)>10(5) M(-1). This strategy makes it possible to direct the formation of double-helical heterodimers. On the basis of solution- and solid-state structural data, this intercalation resulted in an increase in the central-cavity size to give a new interior volume of approximately 150 Å(3). PMID:25284711

  10. Inhibitors of swelling-activated chloride channels increase infarct size and apoptosis in rabbit myocardium.

    PubMed

    Souktani, Rachid; Ghaleh, Bijan; Tissier, Renaud; d'Anglemont de Tassigny, Alexandra; Aouam, Karim; Bedossa, Pierre; Charlemagne, Danièle; Samuel, Janelyse; Henry, Patrick; Berdeaux, Alain

    2003-10-01

    Apoptosis is a significant contributor to myocardial cell death during ischemia-reperfusion and swelling-activated chloride channels (I(Cl,swell)) contribute to apoptosis. However, the relationship between I(Cl,swell) ischemia-reperfusion and apoptosis remains unknown. To further investigate this, New Zealand rabbits underwent a 20-min coronary artery occlusion (CAO) followed by 72 h of coronary artery reperfusion (CAR). Two I(Cl,swell) blockers, 5-nitro-2-[3-phenylpropylamino]benzoic acid (NPPB) and indanyloxyacetic acid 94 (IAA-94) (both 1 mg/kg), were administered prior to CAO and throughout the 72 h CAR. Infarct size (IS) was increased with NPPB and IAA-94 compared with control (vehicle) rabbits (51 +/- 2% and 48 +/- 3% and vs. 35 +/- 2%, respectively, P < 0.05). Similar results were found when NPPB was administered only during the reperfusion period. The percentage of TUNEL-positive nuclei in the border zone of the infarct was increased with NPPB compared with control (37 +/- 2% vs. 25 +/- 31%, P < 0.05) as well as the number of cytoplasmic histone-associated DNA fragments (0.45 +/- 0.06 vs. 0.33 +/- 0.04 absorbance units, P < 0.05). These findings support the concept that I(Cl,swell) channels play an important role in the determination of myocardial infarct size and apoptosis during ischemia-reperfusion. PMID:14703716

  11. Increase in Growth Cone Size Correlates with Decrease in Neurite Growth Rate

    PubMed Central

    Ren, Yuan

    2016-01-01

    Several important discoveries in growth cone cell biology were made possible by the use of growth cones derived from cultured Aplysia bag cell neurons, including the characterization of the organization and dynamics of the cytoskeleton. The majority of these Aplysia studies focused on large growth cones induced by poly-L-lysine substrates at early stages in cell culture. Under these conditions, the growth cones are in a steady state with very little net advancement. Here, we offer a comprehensive cellular analysis of the motile behavior of Aplysia growth cones in culture beyond this pausing state. We found that average growth cone size decreased with cell culture time whereas average growth rate increased. This inverse correlation of growth rate and growth cone size was due to the occurrence of large growth cones with a peripheral domain larger than 100 μm2. The large pausing growth cones had central domains that were less consistently aligned with the direction of growth and could be converted into smaller, faster-growing growth cones by addition of a three-dimensional collagen gel. We conclude that the significant lateral expansion of lamellipodia and filopodia as observed during these culture conditions has a negative effect on neurite growth. PMID:27274874

  12. Organelle size control - increasing vacuole content activates SNAREs to augment organelle volume through homotypic fusion.

    PubMed

    Desfougères, Yann; Neumann, Heinz; Mayer, Andreas

    2016-07-15

    Cells control the size of their compartments relative to cell volume, but there is also size control within each organelle. Yeast vacuoles neither burst nor do they collapse into a ruffled morphology, indicating that the volume of the organellar envelope is adjusted to the amount of content. It is poorly understood how this adjustment is achieved. We show that the accumulating content of yeast vacuoles activates fusion of other vacuoles, thus increasing the volume-to-surface ratio. Synthesis of the dominant compound stored inside vacuoles, polyphosphate, stimulates binding of the chaperone Sec18/NSF to vacuolar SNAREs, which activates them and triggers fusion. SNAREs can only be activated by lumenal, not cytosolic, polyphosphate (polyP). Control of lumenal polyP over SNARE activation in the cytosol requires the cytosolic cyclin-dependent kinase Pho80-Pho85 and the R-SNARE Nyv1. These results suggest that cells can adapt the volume of vacuoles to their content through feedback from the vacuole lumen to the SNAREs on the cytosolic surface of the organelle. PMID:27252384

  13. The phylogenetic structure of plant-pollinator networks increases with habitat size and isolation.

    PubMed

    Aizen, Marcelo A; Gleiser, Gabriela; Sabatino, Malena; Gilarranz, Luis J; Bascompte, Jordi; Verdú, Miguel

    2016-01-01

    Similarity among species in traits related to ecological interactions is frequently associated with common ancestry. Thus, closely related species usually interact with ecologically similar partners, which can be reinforced by diverse co-evolutionary processes. The effect of habitat fragmentation on the phylogenetic signal in interspecific interactions and correspondence between plant and animal phylogenies is, however, unknown. Here, we address to what extent phylogenetic signal and co-phylogenetic congruence of plant-animal interactions depend on habitat size and isolation by analysing the phylogenetic structure of 12 pollination webs from isolated Pampean hills. Phylogenetic signal in interspecific interactions differed among webs, being stronger for flower-visiting insects than plants. Phylogenetic signal and overall co-phylogenetic congruence increased independently with hill size and isolation. We propose that habitat fragmentation would erode the phylogenetic structure of interaction webs. A decrease in phylogenetic signal and co-phylogenetic correspondence in plant-pollinator interactions could be associated with less reliable mutualism and erratic co-evolutionary change. PMID:26493295

  14. Decreased Rate of Evolution in Y Chromosome STR Loci of Increased Size of the Repeat Unit

    PubMed Central

    Järve, Mari; Zhivotovsky, Lev A.; Rootsi, Siiri; Help, Hela; Rogaev, Evgeny I.; Khusnutdinova, Elza K.; Kivisild, Toomas; Sanchez, Juan J.

    2009-01-01

    Background Polymorphic Y chromosome short tandem repeats (STRs) have been widely used in population genetic and evolutionary studies. Compared to di-, tri-, and tetranucleotide repeats, STRs with longer repeat units occur more rarely and are far less commonly used. Principal Findings In order to study the evolutionary dynamics of STRs according to repeat unit size, we analysed variation at 24 Y chromosome repeat loci: 1 tri-, 14 tetra-, 7 penta-, and 2 hexanucleotide loci. According to our results, penta- and hexanucleotide repeats have approximately two times lower repeat variance and diversity than tri- and tetranucleotide repeats, indicating that their mutation rate is about half of that of tri- and tetranucleotide repeats. Thus, STR markers with longer repeat units are more robust in distinguishing Y chromosome haplogroups and, in some cases, phylogenetic splits within established haplogroups. Conclusions Our findings suggest that Y chromosome STRs of increased repeat unit size have a lower rate of evolution, which has significant relevance in population genetic and evolutionary studies. PMID:19789645

  15. When bigger is not better: intraspecific competition for pollination increases with population size in invasive milkweeds.

    PubMed

    Ward, Megan; Johnson, Steven D; Zalucki, Myron P

    2013-04-01

    One of the essential requirements for an introduced plant species to become invasive is an ability to reproduce outside the native range, particularly when initial populations are small. If a reproductive Allee effect is operating, plants in small populations will have reduced reproductive success relative to plants in larger populations. Alternatively, if plants in small populations experience less competition for pollination than those in large populations, they may actually have higher levels of reproductive success than plants in large populations. To resolve this uncertainty, we investigated how the per capita fecundity of plants was affected by population size in three invasive milkweed species. Field surveys of seed production in natural populations of different sizes but similar densities were conducted for three pollinator-dependent invasive species, namely Asclepias curassavica, Gomphocarpus fruticosus and G. physocarpus. Additionally, supplemental hand-pollinations were performed in small and large populations in order to determine whether reproductive output was limited by pollinator activity in these populations. Reproductive Allee effects were not detected in any of the study species. Instead, plants in small populations exhibited remarkably high levels of reproductive output compared to those in large populations. Increased fruit production following supplemental hand-pollinations suggested that the lower reproductive output of naturally pollinated plants in large populations is a consequence of pollen limitation rather than limitation due to abiotic resources. This is consistent with increased intraspecific competition for pollination amongst plants in large populations. It is likely that the invasion of these milkweed species in Australia has been enhanced because plants in small founding populations experience less intraspecific competition for pollinators than those in large populations, and thus have the ability to produce copious amounts of

  16. Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

    NASA Astrophysics Data System (ADS)

    Lindsey, Adam C.; Zhuravleva, Mariya; Wu, Yuntao; Stand, Luis; Loyd, Matthew; Gokhale, Sasmit; Koschan, Merry; Melcher, Charles L.

    2016-09-01

    KCaI3:Eu crystals have been identified as very promising for use in spectroscopic detector applications related to nuclear nonproliferation and domestic security efforts. Initial studies have shown for small crystals a few mm3 in size with 3% europium dopant concentration, a high light yield of >70,000 ph/MeV and energy resolution of ≈3% at 662 keV is attainable which is comparable with the highest performance scintillators discovered. In this work, single crystals of KCaI3 with a range of Eu2+ doping between 0 and 5 at% substituting for Ca2+ were grown at 22 mm diameter and their performance for gamma-ray spectroscopy studied. Comparisons among crystals approximately Ø22 mm×22 mm (8.4 cm3 or ≈0.5 in3) provide a more accurate understanding of how scintillation performance changes with Eu doping and increased crystal size. KCaI3 in the undoped form is shown to be a highly efficient intrinsic scintillator with a defect-related emission at 404 nm which coexists with the Eu2+ 5d-4f emission in low dopant concentrations and is completely re-absorbed in more heavily doped crystals. For larger crystals, effects from self-absorption due to Eu activation become more evident by a near doubling of decay time for 0.5 in3 crystals as the activator is increased from 0.5 to 5.0 at% Eu. Comparisons of pulse-height spectra obtained for Ø22 mm×22 mm cylinders with varying Eu concentration suggests best performance is achieved using lower Eu additions closer to 0.5-1.0 at%. Using a modified crystal packaging featuring an offset reflector geometry, 0.5 in3 crystals of KCaI3:Eu can attain under 4% energy resolution at 662 keV.

  17. Maintained cocaine self-administration is determined by quantal responses: implications for the measurement of antagonist potency.

    PubMed

    Norman, Andrew B; Tabet, Michael R; Norman, Mantana K; Tsibulsky, Vladimir L

    2014-02-01

    The change in frequency of cocaine self-administration as a function of the unit dose is widely assumed to represent a graded pharmacodynamic response. Alternatively, a pharmacological theory states that during maintained self-administration, a quantal response occurs at a minimum maintained cocaine concentration (satiety threshold). Rats self-administered cocaine at unit doses spanning an 8-fold range from 0.75 to 6 µmol/kg. Despite an approximately 7-fold difference in the interinjection intervals, there were no differences in the plasma cocaine concentration at the time of lever press across this range of unit doses, consistent with the satiety threshold representing an equiactive cocaine concentration. Because self-administration always occurs when cocaine concentrations decline back to the satiety threshold, this behavior represents a process of automatic back titration of equiactive agonist concentrations. Therefore, the lower frequency of self-administration at higher unit doses is caused by an increase in the duration of the cocaine-induced satiety response, and the graded dose-frequency relationship is due to cocaine pharmacokinetics. After the interinjection intervals at a particular unit dose were stable, rats were injected with the competitive D₁-like dopamine receptor antagonist R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH23390; 15 nmol/kg intravenously) and the session continued. At all cocaine unit doses, SCH23390 accelerated self-administration with a concomitant increase in the calculated satiety threshold, and these equiactive cocaine concentration ratios were independent of the cocaine unit dose. Therefore, the measurement of antagonist potency requires only a single unit dose of cocaine, selected on the basis of convenience, and using multiple cocaine unit doses is redundant. PMID:24307200

  18. Mouse motor nerve terminal immunoreactivity to synaptotagmin II during sustained quantal transmitter release.

    PubMed

    Angaut-Petit, D; Juzans, P; Molgó, J; Faille, L; Seagar, M J; Takahashi, M; Shoji-Kasai, Y

    1995-05-29

    An antibody directed against the lumenal NH2-terminus of synaptotagmin II was used to examine the distribution of this vesicular protein either after spontaneous acetylcholine release or after sustained release induced by La3+ or alpha-latrotoxin, in conditions that prevent endocytosis. The detection of the epitope was examined in the presence or absence of Triton X-100. We show that, in resting conditions of transmitter release, permeabilization of nerve terminal membranes is required for obvious detection of synaptotagmin Ii immunoreactivity whereas during sustained rates of quantal release, permeabilization is not necessary. These data indicate that, in the latter conditions, synaptotagmin II is incorporated into the terminal axolemma and its intravesicular domain exposed at the extracellular nerve terminal surface. PMID:7552284

  19. Territory Tenure Increases with Repertoire Size in Brownish-Flanked Bush Warbler

    PubMed Central

    Xia, Canwei; Wei, Chentao; Zhang, Yanyun

    2015-01-01

    Song repertoire size is often cited as a classic example of a secondary sexual trait in birds. Models of sexual selection and empirical tests of their predictions have often related secondary sexual traits to longevity. However, the relationship between repertoire size and longevity is unclear. Using capture-mark-recapture studies in two populations of the brownish-flanked bush warbler Cettia fortipes, we found that males with a repertoire size of three maintained territory tenure for a longer duration than did males with a repertoire size of two. These results provide evidence that even a minimal difference in repertoire size can serve as a potential signal of territory tenure capability. PMID:25822524

  20. Increasing zooplankton size diversity enhances the strength of top-down control on phytoplankton through diet niche partitioning.

    PubMed

    Ye, Lin; Chang, Chun-Yi; García-Comas, Carmen; Gong, Gwo-Ching; Hsieh, Chih-Hao

    2013-09-01

    1. The biodiversity-ecosystem functioning debate is a central topic in ecology. Recently, there has been a growing interest in size diversity because body size is sensitive to environmental changes and is one of the fundamental characteristics of organisms linking many ecosystem properties. However, how size diversity affects ecosystem functioning is an important yet unclear issue. 2. To fill the gap, with large-scale field data from the East China Sea, we tested the novel hypothesis that increasing zooplankton size diversity enhances top-down control on phytoplankton (H1) and compared it with five conventional hypotheses explaining the top-down control: flatter zooplankton size spectrum enhances the strength of top-down control (H2); nutrient enrichment lessens the strength of top-down control (H3); increasing zooplankton taxonomic diversity enhances the strength of top-down control (H4); increasing fish predation decreases the strength of top-down control of zooplankton on phytoplankton through trophic cascade (H5); increasing temperature intensifies the strength of top-down control (H6). 3. The results of univariate analyses support the hypotheses based on zooplankton size diversity (H1), zooplankton size spectrum (H2), nutrient (H3) and zooplankton taxonomic diversity (H4), but not the hypotheses based on fish predation (H5) and temperature (H6). More in-depth analyses indicate that zooplankton size diversity is the most important factor in determining the strength of top-down control on phytoplankton in the East China Sea. 4. Our results suggest a new potential mechanism that increasing predator size diversity enhances the strength of top-down control on prey through diet niche partitioning. This mechanism can be explained by the optimal predator-prey body-mass ratio concept. Suppose each size group of zooplankton predators has its own optimal phytoplankton prey size, increasing size diversity of zooplankton would promote diet niche partitioning of predators

  1. Somatostatin analogue, octreotide, reduces increased glomerular filtration rate and kidney size in insulin-dependent diabetes

    SciTech Connect

    Serri, O.; Beauregard, H.; Brazeau, P.; Abribat, T.; Lambert, J.; Harris, A.; Vachon, L. Sandoz Canada Inc., Dorval, Quebec )

    1991-02-20

    To determine whether treatment with a somatostatin analogue can reduce kidney hyperfiltration and hypertrophy in insulin-dependent diabetes mellitus, the authors studied 11 patients with insulin-dependent diabetes mellitus and glomerular hyperfiltration. The patients were assigned randomly to receive continuous subcutaneous infusion of either octreotide, 300 {mu}g/24 h (five patients) or placebo (six patients) for 12 weeks. At baseline, mean glomerular filtration rate and mean total kidney volume were not significantly different in the two groups. However, after 12 weeks of treatment, the mean glomerular filtration rate was significantly lower in the octreotide group than in the placebo group. Furthermore, the mean total kidney volume was significantly lower after treatment in the octreotide group than in the placebo group. Glycemic control did not change significantly in either group. They conclude that subcutaneous infusion of octreotide for 12 weeks reduces increased glomerular filtration rate and kidney size in patients with insulin-dependent diabetes mellitus despite the fact that glycemic control remains unchanged.

  2. Enhanced Sucrose Loading Improves Rice Yield by Increasing Grain Size1[OPEN

    PubMed Central

    Wang, Liang; Lu, Qingtao

    2015-01-01

    Yield in cereals is a function of grain number and size. Sucrose (Suc), the main carbohydrate product of photosynthesis in higher plants, is transported long distances from source leaves to sink organs such as seeds and roots. Here, we report that transgenic rice plants (Oryza sativa) expressing the Arabidopsis (Arabidopsis thaliana) phloem-specific Suc transporter (AtSUC2), which loads Suc into the phloem under control of the phloem protein2 promoter (pPP2), showed an increase in grain yield of up to 16% relative to wild-type plants in field trials. Compared with wild-type plants, pPP2::AtSUC2 plants had larger spikelet hulls and larger and heavier grains. Grain filling was accelerated in the transgenic plants, and more photoassimilate was transported from the leaves to the grain. In addition, microarray analyses revealed that carbohydrate, amino acid, and lipid metabolism was enhanced in the leaves and grain of pPP2::AtSUC2 plants. Thus, enhancing Suc loading represents a promising strategy to improve rice yield to feed the global population. PMID:26504138

  3. Maternal investment, sibling competition, and offspring survival with increasing litter size and parity in pigs (Sus scrofa).

    PubMed

    Andersen, Inger Lise; Nævdal, Eric; Bøe, Knut Egil

    2011-06-01

    The aim of this study was to examine the effects of litter size and parity on sibling competition, piglet survival, and weight gain. It was predicted that competition for teats would increase with increasing litter size, resulting in a higher mortality due to maternal infanticide (i.e., crushing) and starvation, thus keeping the number of surviving piglets constant. We predicted negative effects on weight gain with increasing litter size. Based on maternal investment theory, we also predicted that piglet mortality would be higher for litters born late in a sow's life and thus that the number of surviving piglets would be higher in early litters. As predicted, piglet mortality increased with increasing litter size both due to an increased proportion of crushed piglets, where most of them failed in the teat competition, and due to starvation caused by increased sibling competition, resulting in a constant number of survivors. Piglet weight at day 1 and growth until weaning also declined with increasing litter size. Sows in parity four had higher piglet mortality due to starvation, but the number of surviving piglets was not affected by parity. In conclusion, piglet mortality caused by maternal crushing of piglets, many of which had no teat success, and starvation caused by sibling competition, increased with increasing litter size for most sow parities. The constant number of surviving piglets at the time of weaning suggests that 10 to 11 piglets could be close to the upper limit that the domestic sow is capable of taking care of. PMID:21743767

  4. Ostracod body size trends do not follow either Bergmann's rule or Cope's rule during periods of constant temperature increase

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Seshadri, P.; Amin, V.; Heim, N. A.; Payne, J.

    2013-12-01

    Over time, organisms have adapted to changing environments by evolving to be larger or smaller. Scientists have described body-size trends using two generalized theories. Bergmann's rule states that body size is inversely related to temperature, and Cope's rule establishes an increase over time. Cope's rule has been hypothesized as a temporal manifestation of Bergmann's rule, as the temperature of the Earth has consistently decreased over time and mean body size has increased. However, during times of constant temperature increase, Bergmann's rule and Cope's rule predict opposite effects on body size. Our goal was to clarify this relationship using both accessible proxies of historic temperature - atmospheric CO2 levels and paleo-latitude. We measured ostracod lengths throughout the Paleozoic and Mesozoic eras (using the Catalogue of Ostracoda) and utilized ostracod latitudinal information from the Paleobiology Database. By closely studying body-size trends during four time periods of constant CO2 increase across spectrums of time and latitude, we were able to compare the effects of Cope's and Bergmann's rule. The correlation, p-values, and slopes of each of our graphs showed that there is no clear relationship between body size and each of these rules in times of temperature increase, both latitudinally and temporally. Therefore, both Cope's and Bergmann's rule act on marine ostracods and no rule is dominant, though our results more strongly disprove the latitudinal variation in ostracod size.

  5. Large increase in nest size linked to climate change: an indicator of life history, senescence and condition.

    PubMed

    Møller, Anders Pape; Nielsen, Jan Tøttrup

    2015-11-01

    Many animals build extravagant nests that exceed the size required for successful reproduction. Large nests may signal the parenting ability of nest builders suggesting that nests may have a signaling function. In particular, many raptors build very large nests for their body size. We studied nest size in the goshawk Accipiter gentilis, which is a top predator throughout most of the Nearctic. Both males and females build nests, and males provision their females and offspring with food. Nest volume in the goshawk is almost three-fold larger than predicted from their body size. Nest size in the goshawk is highly variable and may reach more than 600 kg for a bird that weighs ca. 1 kg. While 8.5% of nests fell down, smaller nests fell down more often than large nests. There was a hump-shaped relationship between nest volume and female age, with a decline in nest volume late in life, as expected for senescence. Clutch size increased with nest volume. Nest volume increased during 1977-2014 in an accelerating fashion, linked to increasing spring temperature during April, when goshawks build and start reproduction. These findings are consistent with nest size being a reliable signal of parental ability, with large nest size signaling superior parenting ability and senescence, and also indicating climate warming. PMID:26154876

  6. Measurement of quantal secretion induced by ouabain and its correlation with depletion of synaptic vesicles.

    PubMed

    Haimann, C; Torri-Tarelli, F; Fesce, R; Ceccarelli, B

    1985-11-01

    Ouabain (0.1 and 0.05 mM) was applied to frog cutaneous pectoris nerve-muscle preparations bathed in modified Ringer's solution containing either 1.8 mM Ca2+ (and 4 mM Mg2+) or no added Ca2+ (4 mM Mg2+ and 1 mM EGTA). During the intense quantal release of acetylcholine (ACh) induced by ouabain, the parameters of the miniature endplate potentials (mepps) were deduced from the variance, skew, and power spectra of the endplate recordings by applying a recently described modification of classical fluctuation analysis. Often the high frequency of mepps is not stationary; therefore, the signal was high-pass filtered (time constant of the resistance-capacitance filter of 2 ms) to remove the errors introduced by nonstationarity. When ouabain was applied in the presence of Ca2+, mepp frequency started to rise exponentially after a lag of 1.5-2 h, reached an average peak frequency of 1,300/s in approximately 30 min, and then suddenly subsided to low level (10/s). In Ca2+-free solution, after a shorter lag (1-1.5 h), mepp frequency rose to peak rate of 700/s in approximately 20 min and then gradually subsided. In spite of the different time course of secretion in the two experimental conditions, the cumulative quantal release was not significantly different (7.4 +/- 1.3 X 10(5) in Ca2+-containing and 8.8 +/- 2.7 X 10(5) in Ca2+-free solutions). 60 min after the peak secretion, the muscles were fixed for observation in the electron microscope. Morphometric analysis on micrographs of neuromuscular junctions revealed in both cases a profound depletion of synaptic vesicles and deep infoldings of presynaptic membrane. This rapid depletion and the lack of uptake of horseradish peroxidase suggest that ouabain impairs the recycling process that tends to conserve the vesicle population during intense secretion of neurotransmitter. The good correlation observed between the reduction in the store of synaptic vesicles and the total number of quanta of ACh secreted in the absence of a

  7. Asymmetric forceps increase fighting success among males of similar size in the maritime earwig

    PubMed Central

    Munoz, Nicole E.; Zink, Andrew G.

    2012-01-01

    Extreme asymmetric morphologies are hypothesized to serve an adaptive function that counteracts sexual selection for symmetry. However direct tests of function for asymmetries are lacking, particularly in the context of animal weapons. The weapon of the maritime earwig, Anisolabis maritima, exhibits sizeable variation in the extent of directional asymmetry within and across body sizes, making it an ideal candidate for investigating the function of asymmetry. In this study, we characterized the extent of weapon asymmetry, characterized the manner in which asymmetric weapons are used in contests, staged dyadic contests between males of different size classes and analyzed the correlates of fighting success. In contests between large males, larger individuals won more fights and emerged as the dominant male. In contests between small males, however, weapon asymmetry was more influential in predicting overall fighting success than body size. This result reveals an advantage of asymmetric weaponry among males that are below the mean size in the population. A forceps manipulation experiment suggests that asymmetry may be an indirect, correlate of a morphologically independent factor that affects fighting ability. PMID:22984320

  8. Automated thinning increases uniformity of in-row spacing and plant size in romaine lettuce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low availability and high cost of farm hand labor make automated thinners a faster and cheaper alternative to hand thinning in lettuce (Lactuca sativa L.). However, the effects of this new technology on uniformity of plant spacing and size as well as crop yield are not proven. Three experiments wer...

  9. Relative head size increase using an anatomic dual mobility hip prosthesis compared to traditional hip arthroplasty: impact on hip stability.

    PubMed

    D'Apuzzo, Michele R; Nevelos, Jim; Yeager, Alyssa; Westrich, Geoffrey H

    2014-09-01

    Smaller head sizes and head/cup ratios make cups smaller than 50mm and larger than 58mm, more prone to dislocation. Using computer modeling, we compared average head sizes and posterior horizontal dislocation distance (PHDD) in two 78-patient matched cohorts. Cup sizes were small (≤50mm) or large (≥58mm). The control cohort had conventional fixed bearing prostheses, while the experimental cohort had anatomical dual mobility (ADM) hip prostheses. ADM cups have larger average head sizes and PHDD than traditional fixed bearing prostheses by 11.5mm and 80% for cups ≤50mm, and 16.3mm and 90% for cups ≥58mm. Larger head sizes and increased head/cup ratio may allow the ADM prosthesis to reduce the incidence of dislocation. PMID:24997653

  10. Increasing zooplankton size diversity enhances the strength of top-down control on phytoplankton in the East China Sea

    NASA Astrophysics Data System (ADS)

    Ye, L.; Chang, C.; García-Comas, C.; Gong, G.; Hsieh, C.

    2012-12-01

    Body size is one of the fundamental characteristics of organisms linking many ecosystem properties and functions. Recent studies suggest that environmental changes alter the size structure of pelagic food webs; however, ecosystem consequences of such changes remain unclear. Here we tested our main hypothesis that increasing zooplankton size diversity enhances top-down control on phytoplankton in the East China Sea (H1), as well as five conventional hypotheses explaining the top-down control: shallower zooplankton size spectrum enhances the strength of top-down control (H2); nutrient enrichment lessens the strength of top-down control (H3); increasing zooplankton taxonomic diversity enhances the strength of top-down control (H4); increasing fish predation is linked to decreasing the strength of top-down control of zooplankton on phytoplankton (H5); increasing temperature intensifies the strength of top-down control (H6). While the results of our univariate analyses support H1, H2, H3, and H4, more in depth analyses indicate that zooplankton size diversity is the most important factor in determining the strength of top-down control on phytoplankton in East China Sea. Our results suggest a new potential mechanism that increasing predator size diversity enhances the strength of top-down control on prey through diet niche partitioning. This mechanism can be explained by the concept of optimal predator-prey body-mass ratio concept. Suppose each size group of zooplankton predators has its own optimal phytoplankton prey size, increasing size diversity of zooplankton would promote diet niche partitioning of predators and thus elevates the top-down control.Fig. 1 Scatter plots the relationship between zooplankton/phytoplankton biomass ratio versus (A) zooplankton size diversity, (B) slope of zooplankton size spectrum, (C) Zoolankton Shannon diversity, (D) NO3, (E) PO4, (F) SiO3, (G) water temperature, and (H) fish larvae density in the East China Sea. Table 1. Results of the

  11. Inorganic and organic mercury chloride toxicity to Coturnix: Sensitivity related to age and quantal assessment of physiologic responses

    USGS Publications Warehouse

    Hill, E.F.

    1982-01-01

    The toxicities of mercuric chloride (HgCl(,2)) and methylmercuric chloride (CH(,3)HgCl) were compared for coturnix (Coturnix coturnix japonica) from hatching to adulthood. Comparisons were based on: (1) Median lethal dosages (LD50) derived by administering single peroral and single intramuscular dosages of mercury, (2) median lethal concentrations (LC50) derived by feeding mercury for 5 days, (3) median toxic concentrations (TC50) derived by feeding mercury 9 weeks and measuring plasma enzyme activity, plasma electrolytes, and other blood constituents, and (4) transient changes of various blood chemistries following a single peroral dose of mercury. Acute peroral and intramuscular LD50s for HgCl(,2) and CH(,3)HgCl increased by two- to threefold for coturnix chicks from hatching to 4 weeks of age. Concomitantly, the LC50s also increased, but the important difference between test procedures was that with both single dose routes of exposure the toxicity ratios, i.e., HgCl(,2)/CH(,3)HgCl, at each age were about 2 to 2.5 compared to about 100 for the LC50s. For example, at 2 weeks of age the peroral LD50s for HgCl(,2) and CH(,3)HgCl were 42 and 18 mg/kg; the dietary LC50s were 5086 and 47 ppm for HgCl(,2) and CH(,3)HgCl. The 9 week feeding trial was not associated with gross effects from either HgCl(,2) at 0.5 to 32 ppm or CH(,3)HgCl at 0.125 to 8 ppm. However, subtle responses were detected for the plasma enzymes aspartate aminotransferase, lactate dehydrogenase, and ornithine carbamoyl transferase and could be quantified by probit analysis. This quantal procedure was based on establishment of a normal value for each enzyme and classing outliers as respondents. A 'hazard index' based on the TC50 for an enzyme divided by the LD50 or LC50 was introduced. The single oral dosages of HgCl(,2) and CH(,3)HgCl showed that ratios of alanine aminotransferase, lactate dehydrogenase, and orinthine carbamoyl transferase for the liver and kidneys of adult coturnix were opposite from

  12. The analysis of dose-response curve from bioassays with quantal response: Deterministic or statistical approaches?

    PubMed

    Mougabure-Cueto, G; Sfara, V

    2016-04-25

    Dose-response relations can be obtained from systems at any structural level of biological matter, from the molecular to the organismic level. There are two types of approaches for analyzing dose-response curves: a deterministic approach, based on the law of mass action, and a statistical approach, based on the assumed probabilities distribution of phenotypic characters. Models based on the law of mass action have been proposed to analyze dose-response relations across the entire range of biological systems. The purpose of this paper is to discuss the principles that determine the dose-response relations. Dose-response curves of simple systems are the result of chemical interactions between reacting molecules, and therefore are supported by the law of mass action. In consequence, the shape of these curves is perfectly sustained by physicochemical features. However, dose-response curves of bioassays with quantal response are not explained by the simple collision of molecules but by phenotypic variations among individuals and can be interpreted as individual tolerances. The expression of tolerance is the result of many genetic and environmental factors and thus can be considered a random variable. In consequence, the shape of its associated dose-response curve has no physicochemical bearings; instead, they are originated from random biological variations. Due to the randomness of tolerance there is no reason to use deterministic equations for its analysis; on the contrary, statistical models are the appropriate tools for analyzing these dose-response relations. PMID:26952004

  13. Salt stress increases content and size of glutenin macropolymers in wheat grain.

    PubMed

    Zhang, Xiaxiang; Shi, Zhiqiang; Tian, Youjia; Zhou, Qin; Cai, Jian; Dai, Tingbo; Cao, Weixing; Pu, Hanchun; Jiang, Dong

    2016-04-15

    Addition of salt solution in making wheat dough improves viscoelasticity. However, the effect of native salt fortification on dough quality is unclear. Here, wheat plants were subjected to post-anthesis salt stress to modify salt ion content in grains. The contents of Na(+) and K(+), high-molecular-weight glutenin subunits (HMW-GS), glutenin macropolyers (GMP) and amino acids in mature grains were measured. As NaCl concentration in soil increased, grain yield decreased while Na(+) and K(+) contents increased. The contents of amino acids, HMW-GS and GMP in grains also increased, especially when NaCl concentration exceeded 0.45%. Fraction of GMP larger than 10 μm was also increased. Na(+) and K(+) contents were significantly positively correlated to GMP and total HMW-GS contents, and to large GMP fraction. PMID:26616983

  14. Increased Silver Activity for Direct Propylene Epoxidation via Subnanometer Size Effects

    SciTech Connect

    Lei, Y.; Mehmood, Faisal; Lee, Sang Soo; Greeley, Jeffrey P.; Lee, Byeongdu; Seifert, Soenke; Winans, R. E.; Elam, J. W.; Meyer, R. J.; Redfern, Paul C.; Teschner, D.; Schlogl, Robert; Pellin, M. J.; Curtiss, Larry A.; Vajda, S.

    2010-04-09

    Production of the industrial chemical propylene oxide is energy-intensive and environmentally unfriendly. Catalysts based on bulk silver surfaces with direct propylene epoxidation by molecular oxygen have not resolved these problems because of substantial formation of carbon dioxide. We found that unpromoted, size-selected Ag3 clusters and ~3.5-nanometer Ag nanoparticles on alumina supports can catalyze this reaction with only a negligible amount of carbon dioxide formation and with high activity at low temperatures. Density functional calculations show that, relative to extended silver surfaces, oxidized silver trimers are more active and selective for epoxidation because of the open-shell nature of their electronic structure. The results suggest that new architectures based on ultrasmall silver particles may provide highly efficient catalysts for propylene epoxidation.

  15. Did greater burial depth increase the seed size of domesticated legumes?

    PubMed

    Kluyver, Thomas A; Charles, Michael; Jones, Glynis; Rees, Mark; Osborne, Colin P

    2013-10-01

    The independent domestication of crop plants in several regions of the world formed the basis of human civilizations, and attracts considerable interest from archaeologists and biologists. Selection under cultivation led to a suite of domestication traits which distinguish crops from their wild progenitors, including larger seeds in most seed crops. This selection may be classified as 'conscious' or 'unconscious' selection according to whether humans were aware of the changes that they were driving. The hypothesis that human cultivation buried seeds deeper than natural dispersal, exerting unconscious selection favouring larger seeds with greater reserves, was tested. Using a comparative approach, accessions of eight grain legumes, originating from independent domestication centres across several continents, were sampled. Seeds were planted at different depths in a controlled environment, and seedling emergence scored for 5 weeks after sowing. Domestication in all species was associated with increased seed mass. In three species, greater mass was not correlated with increased ability to emerge from depth. In five species, emergence depth did correlate with mass, suggesting that selection during domestication may have acted on emergence depth. However, domestication only had a significant effect in two of these species (lentil and mung bean), and the increase in depth was no more than predicted by a cube-root allometric relationship with seed mass. The results do not support the hypothesis that burial under cultivation was a general selection mechanism for increased seed mass during the domestication of grain legumes, but it may have acted in particular species or regions. PMID:24058143

  16. One Size Fits All: The Increasing Standardisation of English Teachers' Work in England

    ERIC Educational Resources Information Center

    Goodwyn, Andrew

    2012-01-01

    English teachers in England have experienced a lengthy period of external constraint, increasingly controlling their practice. This constraint was originated in the 1989 National curriculum. Although in its first version it was in harmony with practice, its numerous revisions have moved it a long way from teachers' own values and beliefs. This…

  17. Investigating the Efficacy of a Preschool Vocabulary Intervention Designed to Increase Vocabulary Size and Conceptual Knowledge

    ERIC Educational Resources Information Center

    Dwyer, Julie C.

    2010-01-01

    This dissertation study investigated the efficacy of a supplementary preschool embedded multimedia curriculum that was designed to increase one type of conceptual knowledge: taxonomic categories. Named the World of Words (WOW), this curriculum focused on teaching the properties and concepts associated with seven taxonomic categories and providing…

  18. Hindlimb muscle fibre size and glycogen stores in bank voles with increased aerobic exercise metabolism.

    PubMed

    Jaromin, Ewa; Wyszkowska, Julia; Labecka, Anna Maria; Sadowska, Edyta Teresa; Koteja, Paweł

    2016-02-01

    To test hypotheses concerning physiological factors limiting the rate of aerobic exercise metabolism, we used a unique experimental evolution model: lines of bank voles selected for high swim-induced aerobic metabolism (A) and unselected, control lines (C). We investigated putative adaptations that result in the increased performance of the hindlimb muscle (gastrocnemius joined with plantaris). The body mass-adjusted muscle mass was higher in A-lines (0.093 g) than in C-lines (0.083 g; P=0.01). However, selection did not affect mean muscle fibre cross-sectional area (P=0.34) or glycogen content assessed with a histochemical periodic acid-Schiff reaction (PAS; P=0.82). The results suggest that the increased aerobic performance is achieved by an increase of total muscle mass, without major qualitative changes in the muscle fibre architecture. However, such a conclusion should be treated with caution, because other modifications, such as increased density of capillaries or mitochondria, could occur. PMID:26685167

  19. Male reproductive success increases with alliance size in Indo-Pacific bottlenose dolphins (Tursiops aduncus).

    PubMed

    Wiszniewski, Joanna; Corrigan, Shannon; Beheregaray, Luciano B; Möller, Luciana M

    2012-03-01

    1. Determining the extent of variation in male mating strategies and reproductive success is necessary to understand the fitness benefits of social and cooperative behaviour. 2. This study assesses the reproductive success of male Indo-Pacific bottlenose dolphins in a small embayment population where different behavioural strategies of males have previously been identified. Parentage for 44 sampled calves was examined using 23 microsatellite loci and one mitochondrial DNA marker. Our candidate parent pool of 70 males and 64 females contained individuals sampled from both the embayment and adjacent coastal populations. 3. A moderate level of polygyny was detected in our sample. We assigned paternity of 23 calves to 12 males at the strict 95% confidence level and an additional nine calves to two males at the 80% confidence level. The majority (92%) of successful males were identified as residents to the embayment, and 46% of offspring were located within the same social group or community as their father. 4. Our results suggest that the size of alliances was the best predictor of reproductive success for males in this population, while the strength of association among allied males, alliance stability and male ranging patterns had little influence. In line with predictions for male alliances formed between unrelated individuals, we found that reproductive skew within alliances was not large. 5. Together, our genetic and behavioural analyses demonstrate that alliance formation between male dolphins is a successful strategy to enhance reproductive output. PMID:21981240

  20. Exploring the Relationship between Receptive and Productive Vocabulary Sizes and Their Increased Use by Azerbaijani English Majors

    ERIC Educational Resources Information Center

    Hajiyeva, Konul

    2015-01-01

    This article reports on the results of two studies on receptive and productive vocabulary knowledge of first-year English majors in an English-medium degree programme. The aim of the study is to answer these research questions: (1) to what extent do the receptive and productive vocabulary sizes of English majors increase after a year of…

  1. An intertidal snail shows a dramatic size increase over the past century.

    PubMed

    Fisher, Jonathan A D; Rhile, Erika C; Liu, Harrison; Petraitis, Peter S

    2009-03-31

    Changes in the shell architecture of marine snails enhance defenses and greatly improve survival against predators. In the northwest Atlantic Ocean, shorter and thicker shells have been reported for several species following the introduction of predatory Carcinus maenas crabs early in the 20th century. But we report that the shell lengths of Nucella lapillus actually increased by an average of 22.6% over the past century, with no evidence of shell thickening after correcting for shell length. The increases in shell length were greatest on sheltered shores, highlighting the interaction between wave exposure and the sampling period. Comparisons were based on archived shells collected in 1915-1922 from sites that were resampled in 2007. N. lapillus is an important member of North Atlantic marine ecosystems, and our results suggest that the impacts of historical changes in species' key morphological traits on marine ecosystems remain underappreciated. PMID:19307561

  2. An intertidal snail shows a dramatic size increase over the past century

    PubMed Central

    Fisher, Jonathan A. D.; Rhile, Erika C.; Liu, Harrison; Petraitis, Peter S.

    2009-01-01

    Changes in the shell architecture of marine snails enhance defenses and greatly improve survival against predators. In the northwest Atlantic Ocean, shorter and thicker shells have been reported for several species following the introduction of predatory Carcinus maenas crabs early in the 20th century. But we report that the shell lengths of Nucella lapillus actually increased by an average of 22.6% over the past century, with no evidence of shell thickening after correcting for shell length. The increases in shell length were greatest on sheltered shores, highlighting the interaction between wave exposure and the sampling period. Comparisons were based on archived shells collected in 1915–1922 from sites that were resampled in 2007. N. lapillus is an important member of North Atlantic marine ecosystems, and our results suggest that the impacts of historical changes in species' key morphological traits on marine ecosystems remain underappreciated. PMID:19307561

  3. Reduced salivary gland size and increased presence of epithelial progenitor cells in DLK1-deficient mice.

    PubMed

    García-Gallastegui, P; Luzuriaga, J; Aurrekoetxea, M; Baladrón, V; Ruiz-Hidalgo, M J; García-Ramírez, J J; Laborda, J; Unda, F; Ibarretxe, G

    2016-06-01

    DLK1 (PREF1, pG2, or FA1) is a transmembrane and secreted protein containing epidermal growth factor-like repeats. Dlk1 expression is abundant in many tissues during embryonic and fetal development and is believed to play an important role in the regulation of tissue differentiation and fetal growth. After birth, Dlk1 expression is abolished in most tissues but is possibly reactivated to regulate stem cell activation and responses to injury. We have recently reported that DLK1 regulates many aspects of salivary gland organogenesis. Here, we have extended our studies of the salivary gland phenotype of Dlk1 knock-out mice. We have observed that salivary glands are smaller and weigh significantly less in both Dlk1 knock-out males and females compared with gender and age-matched wild-type mice and regardless of the natural sexual dimorphism in rodent salivary glands. This reduced size correlates with a reduced capacity of Dlk1-deficient mice to secrete saliva after stimulation with pilocarpine. However, histological and ultrastructural analyses of both adult and developing salivary gland tissues have revealed no defects in Dlk1 ((-/-)) mice, indicating that genetic compensation accounts for the relatively mild salivary phenotype in these animals. Finally, despite their lack of severe anomalies, we have found that salivary glands from Dlk1-deficient mice present a higher amount of CK14-positive epithelial progenitors at various developmental stages, suggesting a role for DLK1 in the regulation of salivary epithelial stem cell balance. PMID:26711912

  4. The Ectopic Expression of the Wheat Puroindoline Genes Increase Germ Size and Seed Oil Content in Transgenic Corn

    PubMed Central

    Zhang, Jinrui; Martin, John M.; Beecher, Brian; Lu, Chaofu; Hannah, L. Curtis; Wall, Michael L.; Altosaar, Illimar; Giroux, Michael J.

    2014-01-01

    Plant oil content and composition improvement is a major goal of plant breeding and biotechnology. The Puroindoline a and b (PINA and PINB) proteins together control whether wheat seeds are soft or hard textured and share a similar structure to that of plant non-specific lipid-transfer proteins. Here we transformed corn (Zea mays L.) with the wheat (Triticum aestivum L.) puroindoline genes (Pina and Pinb) to assess their effects upon seed oil content and quality. Pina and Pinb coding sequences were introduced into corn under the control of a corn Ubiquitin promoter. Three Pina/Pinb expression positive transgenic events were evaluated over two growing seasons. The results showed that Pin expression increased germ size significantly without negatively impacting seed size. Germ yield increased 33.8% while total seed oil content was increased by 25.23%. Seed oil content increases were primarily the result of increased germ size. This work indicates that higher oil content corn hybrids having increased food or feed value could be produced via puroindoline expression. PMID:20725765

  5. Overexpression of a rice TIFY gene increases grain size through enhanced accumulation of carbohydrates in the stem.

    PubMed

    Hakata, Makoto; Kuroda, Masaharu; Ohsumi, Akihiro; Hirose, Tatsuro; Nakamura, Hidemitsu; Muramatsu, Masayuki; Ichikawa, Hiroaki; Yamakawa, Hiromoto

    2012-01-01

    Screening of rice full-length cDNA overexpressing (FOX) lines allowed the identification of a TIFY gene, TIFY11b, as a growth-promoting gene whose overexpression increased plant height and seed size. The grains of TIFY11b-overexpressing plants exceeded those of non-transformants in length, width and thickness, resulting in 9-21% increases in grain weight. The increase was achieved by overexpressing the gene in the whole plant body, but not by seed-restricted expression, indicating that seed enlargement is attributable to overexpression in vegetative organs such as the leaf. The whole-body overexpressing plants developed longer leaves along with higher levels of starch and sucrose in the leaf sheath and culm at the heading stage than the non-transformants. Although overexpression of TIFY11b did not alter the photosynthetic rate per leaf area before and after heading, it caused an accumulation of higher levels of the carbohydrate assimilate, probably due to increased photosynthesis per plant, suggesting that the increase in grain size and weight is attained by enhanced accumulation and translocation of the carbohydrate in the culms and leaf sheaths of the transgenic plants. Thus, TIFY11b is a novel grain-size increasing gene. PMID:23132589

  6. Genetic factors associated with population size may increase extinction risks and decrease colonization potential in a keystone tropical pine

    PubMed Central

    del Castillo, Rafael F; Trujillo-Argueta, Sonia; Sánchez-Vargas, Nahúm; Newton, Adrian C

    2011-01-01

    Pioneer species are essential for forest regeneration and ecosystem resilience. Pinus chiapensis is an endangered pioneer key species for tropical montane cloud forest regeneration in Mesoamerica. Human activities have severely reduced some P. chiapensis populations, which exhibited a small or null colonization potential suggesting the involvement of genetic factors associated with small populations. We explored the relationships between (i) population genetic diversity (allozymes) and population size, including sampling size effects, (ii) fitness estimates associated with colonization potential (seed viability and seedling performance) in a common environment and population size, and (iii) fitness estimates and observed heterozygosity in populations with sizes spanning five orders of magnitude. All the estimates of genetic diversity and fitness increased significantly with population size. Low fitness was detected in progenies of small populations of disturbed and undisturbed habitats. Progenies with the lowest observed heterozygosity displayed the lowest fitness estimates, which, in turn, increased with heterozygosity, but seed viability peaked at intermediate heterozygosity values suggesting inbreeding and outbreeding depression. Inbreeding depression appears to be the most immediate genetic factor in population decline. Conservation efforts should try to maintain large and genetically diverse populations, enhance gene flow by restoring connectivity between adjacent populations, and avoid genetically distant individuals. PMID:25568006

  7. Increase of Cloud Droplet Size with Aerosol Optical Depth: An Observational and Modeling Study

    SciTech Connect

    Yuan, Tianle; Li, Zhanqing; Zhang, Renyi; Fan, Jiwen

    2008-02-21

    Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including water vapor swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D spectral-bin microphysics Goddard Cumulus Ensemble model (GCE) which incorporated a reformulation of the Köhler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant CCNs. Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.

  8. Alternative reproductive tactics increase effective population size and decrease inbreeding in wild Atlantic salmon

    PubMed Central

    Perrier, Charles; Normandeau, Éric; Dionne, Mélanie; Richard, Antoine; Bernatchez, Louis

    2014-01-01

    While nonanadromous males (stream-resident and/or mature male parr) contribute to reproduction in anadromous salmonids, little is known about their impacts on key population genetic parameters. Here, we evaluated the contribution of Atlantic salmon mature male parr to the effective number of breeders (Nb) using both demographic (variance in reproductive success) and genetic (linkage disequilibrium) methods, the number of alleles, and the relatedness among breeders. We used a recently published pedigree reconstruction of a wild anadromous Atlantic salmon population in which 2548 fry born in 2010 were assigned parentage to 144 anadromous female and 101 anadromous females that returned to the river to spawn in 2009 and to 462 mature male parr. Demographic and genetic methods revealed that mature male parr increased population Nb by 1.79 and 1.85 times, respectively. Moreover, mature male parr boosted the number of alleles found among progenies. Finally, mature male parr were in average less related to anadromous females than were anadromous males, likely because of asynchronous sexual maturation between mature male parr and anadromous fish of a given cohort. By increasing Nb and allelic richness, and by decreasing inbreeding, the reproductive contribution of mature male parr has important evolutionary and conservation implications for declining Atlantic salmon populations. PMID:25553070

  9. Increased Litter Size and Suckling Intensity Stimulate mRNA of RFamide-related Peptide in Rats

    PubMed Central

    Noroozi, Atefeh; Jafarzadeh Shirazi, Mohammad Reza; Tamadon, Amin; Moghadam, Ali; Niazi, Ali

    2015-01-01

    Background RFamide-related peptide-3 (RFRP-3) inhibits gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) secretion in rats. This study evaluates the effects of litter size and suckling intensity on RFRP mRNA expression in the dorsomedial hypothalamic nucleus (DMH) of rats. Materials and Methods A total of 32 pregnant and 4 non-lactating ovariectomized (control group) Sprague-Dawley rats were used in this experimental study. Lactating rats were allotted to 8 equal groups. In 3 groups, the litter size was adjusted to 5, 10, or 15 pups upon parturition. Dams were allowed to suckle their pups continuously until 8 days postpartum. In the other 3 groups, the litter size was adjusted to 5 pups following birth. These pups were separated from the dams for 6 hours on day 8 postpartum, after which the pups were allowed to suckle for 2.5, 5, or 7.5 minutes prior to killing the dams. In 2 groups, lactating rats with 10 and 15 pups were separated from their pups for 6 hours on day 8 postpartum. In these groups, the pups were allowed to suckle their dams for 5 minutes before the dams were killed. All rats were killed on day 8 postpartum and the DMH was removed from each rat. We evaluated RFRP mRNA expression using realtime polymerase chain reaction (PCR). Results The expression of RFRP mRNA in the DMH increased with increased litter size and suckling intensity compared to the controls. The effect of suckling intensity on the expression of RFRP mRNA was more pronounced compared to the litter size. Conclusion Increased litter size and suckling intensity stimulated RFRP mRNA expression in the DMH which might contribute to lactation anestrus in rats. PMID:26644862

  10. Testing for Depéret's Rule (Body Size Increase) in Mammals using Combined Extinct and Extant Data.

    PubMed

    Bokma, Folmer; Godinot, Marc; Maridet, Olivier; Ladevèze, Sandrine; Costeur, Loïc; Solé, Floréal; Gheerbrant, Emmanuel; Peigné, Stéphane; Jacques, Florian; Laurin, Michel

    2016-01-01

    Whether or not evolutionary lineages in general show a tendency to increase in body size has often been discussed. This tendency has been dubbed "Cope's rule" but because Cope never hypothesized it, we suggest renaming it after Depéret, who formulated it clearly in 1907. Depéret's rule has traditionally been studied using fossil data, but more recently a number of studies have used present-day species. While several paleontological studies of Cenozoic placental mammals have found support for increasing body size, most studies of extant placentals have failed to detect such a trend. Here, we present a method to combine information from present-day species with fossil data in a Bayesian phylogenetic framework. We apply the method to body mass estimates of a large number of extant and extinct mammal species, and find strong support for Depéret's rule. The tendency for size increase appears to be driven not by evolution toward larger size in established species, but by processes related to the emergence of new species. Our analysis shows that complementary data from extant and extinct species can greatly improve inference of macroevolutionary processes. PMID:26508768

  11. Testing for Depéret's Rule (Body Size Increase) in Mammals using Combined Extinct and Extant Data

    PubMed Central

    Bokma, Folmer; Godinot, Marc; Maridet, Olivier; Ladevèze, Sandrine; Costeur, Loïc; Solé, Floréal; Gheerbrant, Emmanuel; Peigné, Stéphane; Jacques, Florian; Laurin, Michel

    2016-01-01

    Whether or not evolutionary lineages in general show a tendency to increase in body size has often been discussed. This tendency has been dubbed “Cope's rule” but because Cope never hypothesized it, we suggest renaming it after Depéret, who formulated it clearly in 1907. Depéret's rule has traditionally been studied using fossil data, but more recently a number of studies have used present-day species. While several paleontological studies of Cenozoic placental mammals have found support for increasing body size, most studies of extant placentals have failed to detect such a trend. Here, we present a method to combine information from present-day species with fossil data in a Bayesian phylogenetic framework. We apply the method to body mass estimates of a large number of extant and extinct mammal species, and find strong support for Depéret's rule. The tendency for size increase appears to be driven not by evolution toward larger size in established species, but by processes related to the emergence of new species. Our analysis shows that complementary data from extant and extinct species can greatly improve inference of macroevolutionary processes. PMID:26508768

  12. Menopausal hormone therapy and breast cancer: what is the true size of the increased risk?

    PubMed Central

    Jones, Michael E; Schoemaker, Minouk J; Wright, Lauren; McFadden, Emily; Griffin, James; Thomas, Dawn; Hemming, Jane; Wright, Karen; Ashworth, Alan; Swerdlow, Anthony J

    2016-01-01

    Background: Menopausal hormone therapy (MHT) increases breast cancer risk; however, most cohort studies omit MHT use after enrolment and many infer menopausal age. Methods: We used information from serial questionnaires from the UK Generations Study cohort to estimate hazard ratios (HRs) for breast cancer among post-menopausal women with known menopausal age, and examined biases induced when not updating data on MHT use and including women with inferred menopausal age. Results: Among women recruited in 2003–2009, at 6 years of follow-up, 58 148 had reached menopause and 96% had completed a follow-up questionnaire. Among 39 183 women with known menopausal age, 775 developed breast cancer, and the HR in relation to current oestrogen plus progestogen MHT use (based on 52 current oestrogen plus progestogen MHT users in breast cancer cases) relative to those with no previous MHT use was 2.74 (95% confidence interval (CI): 2.05–3.65) for a median duration of 5.4 years of current use, reaching 3.27 (95% CI: 1.53–6.99) at 15+ years of use. The excess HR was underestimated by 53% if oestrogen plus progestogen MHT use was not updated after recruitment, 13% if women with uncertain menopausal age were included, and 59% if both applied. The HR for oestrogen-only MHT was not increased (HR=1.00; 95% CI: 0.66–1.54). Conclusions: Lack of updating MHT status through follow-up and inclusion of women with inferred menopausal age is likely to result in substantial underestimation of the excess relative risks for oestrogen plus progestogen MHT use in studies with long follow-up, limited updating of exposures, and changing or short durations of use. PMID:27467055

  13. Modulation of the inflammatory response by increasing fetal wound size or interleukin-10 overexpression determines wound phenotype and scar formation.

    PubMed

    Morris, Michael W; Allukian, Myron; Herdrich, Benjamin J; Caskey, Robert C; Zgheib, Carlos; Xu, Junwang; Dorsett-Martin, Wanda; Mitchell, Marc E; Liechty, Kenneth W

    2014-01-01

    Wound size impacts the threshold between scarless regeneration and reparative healing in the fetus with increased inflammation showed in fetal scar formation. We hypothesized that increased fetal wound size increases pro-inflammatory and fibrotic genes with resultant inflammation and fibroplasia and that transition to scar formation could be reversed by overexpression of interleukin-10 (IL-10). To test this hypothesis, 2-mm and 8-mm dermal wounds were created in mid-gestation fetal sheep. A subset of 8-mm wounds were injected with a lentiviral vector containing the IL-10 transgene (n = 4) or vehicle (n = 4). Wounds were harvested at 3 or 30 days for histology, immunohistochemistry, analysis of gene expression by microarray, and validation with real-time polymerase chain reaction. In contrast to the scarless 2-mm wounds, 8-mm wounds showed scar formation with a differential gene expression profile, increased inflammatory cytokines, decreased CD45+ cells, and subsequent inflammation. Lentiviral-mediated overexpression of the IL-10 gene resulted in conversion to a regenerative phenotype with decreased inflammatory cytokines and regeneration of dermal architecture. In conclusion, increased fetal wounds size leads to a unique gene expression profile that promotes inflammation and leads to scar formation and furthermore, these results show the significance of attenuated inflammation and IL-10 in the transition from fibroplasia to fetal regenerative healing. PMID:24844340

  14. Extinction reverses olfactory fear-conditioned increases in neuron number and glomerular size.

    PubMed

    Morrison, Filomene G; Dias, Brian G; Ressler, Kerry J

    2015-10-13

    Although much work has investigated the contribution of brain regions such as the amygdala, hippocampus, and prefrontal cortex to the processing of fear learning and memory, fewer studies have examined the role of sensory systems, in particular the olfactory system, in the detection and perception of cues involved in learning and memory. The primary sensory receptive field maps of the olfactory system are exquisitely organized and respond dynamically to cues in the environment, remaining plastic from development through adulthood. We have previously demonstrated that olfactory fear conditioning leads to increased odorant-specific receptor representation in the main olfactory epithelium and in glomeruli within the olfactory bulb. We now demonstrate that olfactory extinction training specific to the conditioned odor stimulus reverses the conditioning-associated freezing behavior and odor learning-induced structural changes in the olfactory epithelium and olfactory bulb in an odorant ligand-specific manner. These data suggest that learning-induced freezing behavior, structural alterations, and enhanced neural sensory representation can be reversed in adult mice following extinction training. PMID:26420875

  15. Extinction reverses olfactory fear-conditioned increases in neuron number and glomerular size

    PubMed Central

    Morrison, Filomene G.; Dias, Brian G.; Ressler, Kerry J.

    2015-01-01

    Although much work has investigated the contribution of brain regions such as the amygdala, hippocampus, and prefrontal cortex to the processing of fear learning and memory, fewer studies have examined the role of sensory systems, in particular the olfactory system, in the detection and perception of cues involved in learning and memory. The primary sensory receptive field maps of the olfactory system are exquisitely organized and respond dynamically to cues in the environment, remaining plastic from development through adulthood. We have previously demonstrated that olfactory fear conditioning leads to increased odorant-specific receptor representation in the main olfactory epithelium and in glomeruli within the olfactory bulb. We now demonstrate that olfactory extinction training specific to the conditioned odor stimulus reverses the conditioning-associated freezing behavior and odor learning-induced structural changes in the olfactory epithelium and olfactory bulb in an odorant ligand-specific manner. These data suggest that learning-induced freezing behavior, structural alterations, and enhanced neural sensory representation can be reversed in adult mice following extinction training. PMID:26420875

  16. Bed disturbance via foraging fish increases bedload transport during subsequent high flows and is controlled by fish size and species

    NASA Astrophysics Data System (ADS)

    Pledger, A. G.; Rice, S. P.; Millett, J.

    2016-01-01

    Benthic foraging by fish can modify the nature and rates of fine sediment accrual and the structure and topography of coarse-grained fluvial substrates, with the potential to alter bed material characteristics, particle entrainment thresholds, and bedload transport fluxes. However, knowledge of what controls the nature, extent, and intensity of benthic foraging and the consequent influence of these controls on geomorphic impact remain rudimentary. An ex-situ experiment utilising Barbel Barbus barbus and Chub Leuciscus cephalus extended previous work by considering the role of fish size and species as controls of sediment disturbance by foraging and the implications for bed material characteristics and bedload transport. In a laboratory flume, changes in bed microtopography and structure were measured when a water-worked bed of 5.6-22.6 mm gravels was exposed to four size classes of Barbel (4-5″, 5-6″, 6-8″, 8-10″ in length) and a single size class of Chub (8-10″). In line with other studies that have investigated animal size as a control of zoogeomorphic agency, increasing the size of Barbel had a significant effect on measured disturbance and transport metrics. Specifically, the area of disturbed substrate, foraging depth, and the fish's impact on microtopographic roughness and imbrication all increased as a function of fish size. In a comparison of the foraging effects of like-sized Barbel and Chub, 8-10″ in length, Barbel foraged a larger area of the test bed and had a greater impact on microtopographic roughness and sediment structure. Relative to water-worked beds that were not foraged, bed conditioning by both species was associated with increased bedload transport during the subsequent application of high flows. However, the bedload flux after foraging by Barbel, which is a specialist benthivore, was 150% higher than that following foraging by Chub, which feed opportunistically from the bed, and the total transported mass of sediment was 98

  17. Autopolyploidy differentially influences body size in plants, but facilitates enhanced accumulation of secondary metabolites, causing increased cytosine methylation.

    PubMed

    Lavania, Umesh C; Srivastava, Sarita; Lavania, Seshu; Basu, Surochita; Misra, Nandeesh Kumar; Mukai, Yasuhiko

    2012-08-01

    Whole genome duplication leads to autopolyploidy and brings about an increase in cell size, concentration of secondary metabolites and enhanced cytosine methylation. The increased cell size offers a positive advantage to polyploids for cell-surface-related activities, but there is a differential response to change in body size across species and taxonomic groups. Although polyploidy has been very extensively studied, having genetic, ecological and evolutionary implications, there is no report that underscores the significance of native secondary metabolites vis-à-vis body size with ploidy change. To address this problem we targeted unique diploid-autotetraploid paired sets of eight diverse clones of six species of Cymbopogon- a species complex of aromatic grasses that accumulate qualitatively different monoterpene essential oils (secondary metabolite) in their vegetative biomass. Based on the qualitative composition of essential oils and the plant body size relationship between the diploid versus autotetraploid paired sets, we show that polyploidy brings about enhanced accumulation of secondary metabolites in all cases, but exerts differential effects on body size in various species. It is observed that the accumulation of alcohol-type metabolites (e.g. geraniol) does not inhibit increase in body size with ploidy change from 2× to 4× (r = 0.854, P < 0.01), but aldehyde-type metabolites (e.g. citral) appear to drastically impede body development (r = -0.895). Such a differential response may be correlated to the metabolic steps involved in the synthesis of essential oil components. When changed to tetraploidy, the progenitor diploids requiring longer metabolic steps in production of their secondary metabolites are stressed, and those having shorter metabolite routes better utilize their resources for growth and vigour. In situ immunodetection of 5-methylcytosine sites reveals enhanced DNA methylation in autopolyploids. It is underpinned that the qualitative

  18. Awns reduce grain number to increase grain size and harvestable yield in irrigated and rainfed spring wheat

    PubMed Central

    Rebetzke, G. J.; Bonnett, D. G.; Reynolds, M. P.

    2016-01-01

    Genotypic variation in ear morphology is linked to differences in photosynthetic potential to influence grain yield in winter cereals. Awns contribute to photosynthesis, particularly under water-limited conditions when canopy assimilation is restricted. We assessed performance of up to 45 backcross-derived, awned–awnletted NILs representing four diverse genetic backgrounds in 25 irrigated or rainfed, and droughted environments in Australia and Mexico. Mean environment grain yields were wide-ranging (1.38–7.93 t ha−1) with vegetative and maturity biomass, plant height, anthesis date, spike number, and harvest index all similar (P >0.05) for awned and awnletted NILs. Overall, grain yields of awned–awnletted sister-NILs were equivalent, irrespective of yield potential and genetic background. Awnletted wheats produced significantly more grains per unit area (+4%) and per spike (+5%) reflecting more fertile spikelets and grains in tertiary florets. Increases in grain number were compensated for by significant reductions in grain size (–5%) and increased frequency (+0.8%) of small, shrivelled grains (‘screenings’) to reduce seed-lot quality of awnletted NILs. Post-anthesis canopies of awnletted NILs were marginally warmer over all environments (+0.27 °C) but were not different and were sometimes cooler than awned NILs at cooler air temperatures. Awns develop early and represented up to 40% of total spikelet biomass prior to ear emergence. We hypothesize that the allocation of assimilate to large and rapidly developing awns decreases spikelet number and floret fertility to reduce grain number, particularly in distal florets. Individual grain size is increased to reduce screenings and to increase test weight and milling quality, particularly in droughted environments. Despite the average reduction in grain size, awnless lines could be identified that combined higher grain yield with larger grain size, increased grain protein concentration, and reduced

  19. Awns reduce grain number to increase grain size and harvestable yield in irrigated and rainfed spring wheat.

    PubMed

    Rebetzke, G J; Bonnett, D G; Reynolds, M P

    2016-04-01

    Genotypic variation in ear morphology is linked to differences in photosynthetic potential to influence grain yield in winter cereals. Awns contribute to photosynthesis, particularly under water-limited conditions when canopy assimilation is restricted. We assessed performance of up to 45 backcross-derived, awned-awnletted NILs representing four diverse genetic backgrounds in 25 irrigated or rainfed, and droughted environments in Australia and Mexico. Mean environment grain yields were wide-ranging (1.38-7.93 t ha(-1)) with vegetative and maturity biomass, plant height, anthesis date, spike number, and harvest index all similar (P >0.05) for awned and awnletted NILs. Overall, grain yields of awned-awnletted sister-NILs were equivalent, irrespective of yield potential and genetic background. Awnletted wheats produced significantly more grains per unit area (+4%) and per spike (+5%) reflecting more fertile spikelets and grains in tertiary florets. Increases in grain number were compensated for by significant reductions in grain size (-5%) and increased frequency (+0.8%) of small, shrivelled grains ('screenings') to reduce seed-lot quality of awnletted NILs. Post-anthesis canopies of awnletted NILs were marginally warmer over all environments (+0.27 °C) but were not different and were sometimes cooler than awned NILs at cooler air temperatures. Awns develop early and represented up to 40% of total spikelet biomass prior to ear emergence. We hypothesize that the allocation of assimilate to large and rapidly developing awns decreases spikelet number and floret fertility to reduce grain number, particularly in distal florets. Individual grain size is increased to reduce screenings and to increase test weight and milling quality, particularly in droughted environments. Despite the average reduction in grain size, awnless lines could be identified that combined higher grain yield with larger grain size, increased grain protein concentration, and reduced screenings. PMID

  20. Recovery of Aging-Related Size Increase of Skin Epithelial Cells: In vivo Mouse and In vitro Human Study

    PubMed Central

    Sokolov, Igor; Guz, Natali V.; Iyer, Swaminathan; Hewitt, Amy; Sokolov, Nina A.; Erlichman, Joseph S.; Woodworth, Craig D.

    2015-01-01

    The size increase of skin epithelial cells during aging is well-known. Here we demonstrate that treatment of aging cells with cytochalasin B substantially decreases cell size. This decrease was demonstrated on a mouse model and on human skin cells in vitro. Six nude mice were treated by topical application of cytochalasin B on skin of the dorsal left midsection for 140 days (the right side served as control for placebo treatment). An average decrease in cell size of 56±16% resulted. A reduction of cell size was also observed on primary human skin epithelial cells of different in vitro age (passages from 1 to 8). A cell strain obtained from a pool of 6 human subjects was treated with cytochalasin B in vitro for 12 hours. We observed a decrease in cell size that became statistically significant and reached 20–40% for cells of older passage (6–8 passages) whereas no substantial change was observed for younger cells. These results may be important for understanding the aging processes, and for cosmetic treatment of aging skin. PMID:25807526

  1. Rheotaxis performance increases with group size in a coupled phase model with sensory noise. The effects of noise and group size on rheotaxis

    NASA Astrophysics Data System (ADS)

    Chicoli, A.; Bak-Coleman, J.; Coombs, S.; Paley, D. A.

    2015-12-01

    Many fish exhibit rheotaxis, a behavior in which fish orient themselves relative to flow. Rheotaxis confers many benefits, including energetic cost savings and interception of drifting prey. Despite the fact that most species of fish school during at least some portion of their life, little is known about the importance of rheotactic behavior to schooling fish and, conversely, how the presence of nearby conspecifics affects rheotactic behavior. Understanding how rheotaxis is modified by social factors is thus of ecological importance. Here we present a mathematical model in the form of an all-to-all, coupled-oscillator framework over the non-Euclidean space of fish orientations to model group rheotactic behavior. Individuals in the model measure the orientation of their neighbors and the flow direction relative to their own orientation. These measures are corrupted by sensory noise. We study the effect of sensory noise and group size on internal (i.e., within the school) and external (i.e., with the flow) disagreement in orientation. We find that under noisy environmental conditions, increased group size improves rheotaxis. Results of this study have implications for understanding animal behavior, as well as for potential applications in bio-inspired engineering.

  2. Founding weaver ant queens (Oecophylla longinoda) increase production and nanitic worker size when adopting non-nestmate pupae.

    PubMed

    Ouagoussounon, Issa; Offenberg, Joachim; Sinzogan, Antonio; Adandonon, Appolinaire; Kossou, Dansou; Vayssières, Jean-François

    2015-01-01

    Weaver ants (Oecophylla longinoda Latreille) are used commercially to control pest insects and for protein production. In this respect fast colony growth is desirable for managed colonies. Transplantation of non-nestmate pupae to incipient colonies has been shown to boost colony growth. Our objectives were to find the maximum number of pupae a founding queen can handle, and to measure the associated colony growth. Secondly, we tested if transplantation of pupae led to production of larger nanitic workers (defined as unusually small worker ants produced by founding queens in their first batch of offspring). Forty-five fertilized queens were divided into three treatments: 0 (control), 100 or 300 non-nestmate pupae transplanted to each colony. Pupae transplantation resulted in highly increased growth rates, as pupae were readily adopted by the queens and showed high proportions of surviving (mean = 76%). However, survival was significantly higher when 100 pupae were transplanted compared to transplantation of 300 pupae, indicating that queens were unable to handle 300 pupae adequately and that pupae require some amount of nursing. Nevertheless, within the 60-day experiment the transplantation of 300 pupae increased total colony size more than 10-fold whereas 100 pupae increased the size 5.6 fold, compared to control. This increase was due not only to the individuals added in the form of pupae but also to an increased per capita brood production by the resident queen, triggered by the adopted pupae. The size of hatching pupae produced by the resident queen also increased with the number of pupae transplanted, leading to larger nanitic workers in colonies adopting pupae. In conclusion, pupae transplantation may be used to produce larger colonies with larger worker ants and may thus reduce the time to produce weaver ant colonies for commercial purposes. This in turn may facilitate the implementation of the use of weaver ants. PMID:25995983

  3. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    PubMed Central

    Cai, Yao; Cao, Changqian; He, Xiaoqing; Yang, Caiyun; Tian, Lanxiang; Zhu, Rixiang; Pan, Yongxin

    2015-01-01

    Purpose This study is to demonstrate the nanoscale size effect of ferrimagnetic H-ferritin (M-HFn) nanoparticles on magnetic properties, relaxivity, enzyme mimetic activities, and application in magnetic resonance imaging (MRI) and immunohistochemical staining of cancer cells. Materials and methods M-HFn nanoparticles with different sizes of magnetite cores in the range of 2.7–5.3 nm were synthesized through loading different amounts of iron into recombinant human H chain ferritin (HFn) shells. Core size, crystallinity, and magnetic properties of those M-HFn nanoparticles were analyzed by transmission electron microscope and low-temperature magnetic measurements. The MDA-MB-231 cancer cells were incubated with synthesized M-HFn nanoparticles for 24 hours in Dulbecco’s Modified Eagle’s Medium. In vitro MRI of cell pellets after M-HFn labeling was performed at 7 T. Iron uptake of cells was analyzed by Prussian blue staining and inductively coupled plasma mass spectrometry. Immunohistochemical staining by using the peroxidase-like activity of M-HFn nanoparticles was carried out on MDA-MB-231 tumor tissue paraffin sections. Results The saturation magnetization (Ms), relaxivity, and peroxidase-like activity of synthesized M-HFn nanoparticles were monotonously increased with the size of ferrimagnetic cores. The M-HFn nanoparticles with the largest core size of 5.3 nm exhibit the strongest saturation magnetization, the highest peroxidase activity in immunohistochemical staining, and the highest r2 of 321 mM−1 s−1, allowing to detect MDA-MB-231 breast cancer cells as low as 104 cells mL−1. Conclusion The magnetic properties, relaxivity, and peroxidase-like activity of M-HFn nanoparticles are size dependent, which indicates that M-HFn nanoparticles with larger magnetite core can significantly enhance performance in MRI and staining of cancer cells. PMID:25878496

  4. Nutrient reserves may allow for genome size increase: evidence from comparison of geophytes and their sister non-geophytic relatives

    PubMed Central

    Veselý, Pavel; Bureš, Petr; Šmarda, Petr

    2013-01-01

    Background and Aims The genome size of an organism is determined by its capacity to tolerate genome expansion, given the species' life strategy and the limits of a particular environment, and the ability for retrotransposon suppression and/or removal. In some giant-genomed bulb geophytes, this tolerance is explained by their ability to pre-divide cells in the dormant stages or by the selective advantage of larger cells in the rapid growth of their fleshy body. In this study, a test shows that the tendency for genome size expansion is a more universal feature of geophytes, and is a subject in need of more general consideration. Methods Differences in monoploid genome sizes were compared using standardized phylogenetically independent contrasts in 47 sister pairs of geophytic and non-geophytic taxa sampled across all the angiosperms. The genome sizes of 96 species were adopted from the literature and 53 species were newly measured using flow cytometry with propidium iodide staining. Key Results The geophytes showed increased genome sizes compared with their non-geophytic relatives, regardless of the storage organ type and regardless of whether or not vernal geophytes, polyploids or annuals were included in the analyses. Conclusions The universal tendency of geophytes to possess a higher genome size suggests the presence of a universal mechanism allowing for genome expansion. It is assumed that this is primarily due to the nutrient and energetic independence of geophytes perhaps allowing continuous synthesis of DNA, which is known to proceed in the extreme cases of vernal geophytes even in dormant stages. This independence may also be assumed as a reason for allowing large genomes in some parasitic plants, as well as the nutrient limitation of small genomes of carnivorous plants. PMID:23960044

  5. Nanocrystalline diamond microelectrode arrays fabricated on sapphire technology for high-time resolution of quantal catecholamine secretion from chromaffin cells.

    PubMed

    Carabelli, V; Gosso, S; Marcantoni, A; Xu, Y; Colombo, E; Gao, Z; Vittone, E; Kohn, E; Pasquarelli, A; Carbone, E

    2010-09-15

    The quantal release of oxidizable molecules can be successfully monitored by means of polarized carbon fiber microelectrodes (CFEs) positioned in close proximity to the cell membrane. To partially overcome certain CFE limitations, mainly related to their low spatial resolution and lack of optical transparency, we developed a planar boron-doped nanocrystalline diamond (NCD) prototype, grown on a transparent sapphire wafer. Responsiveness to applied catecholamines as well as the electrochemical and optical properties of the NCD-based device were first characterized by cyclic voltammetry and optical transmittance measurements. By stimulating chromaffin cells positioned on the device with external KCl, well-resolved quantal exocytotic events could be detected either from one NCD microelectrode, or simultaneously from an array of four microelectrodes, indicating that the chip is able to monitor secretory events (amperometric spikes) from a number of isolated chromaffin cells. Spikes detected by the planar NCD device had comparable amplitudes, kinetics and vesicle diameter distributions as those measured by conventional CFEs from the same chromaffin cell. PMID:20570501

  6. First-principles molecular dynamics of liquid alkali metals based on the quantal hypernetted chain theory

    NASA Astrophysics Data System (ADS)

    Kambayashi, Shaw; Chihara, Junzo

    1996-06-01

    A first-principles molecular dynamics (MD) scheme is presented on the basis of the density-functional (DF) theory with use of the the quantal hypernetted chain (QHNC) approximation. The DF theory brings about exact expressions for the ion-electron and ion-ion radial distribution functions (RDF) of an electron-ion mixture as a model of a simple liquid metal. These exact expressions prove that an ion-electron mixture can be treated as a one-component liquid interacting only via a pairwise interaction in the evaluation of the ion-ion RDF, and provide a set of integral equations: one is an exact integral equation for the ion-ion RDF and another for an effective ion-ion interaction, which depends on the ion configuration specified by the ion-ion RDF. Hence, after some approximations are introduced, the MD simulation can be performed to get the ion-ion RDF using the ion-ion interaction determined so as to be consistent to the ion-ion RDF: the MD simulation and the procedure to determine the effective interaction from the QHNC equation are performed iteratively. This MD simulation coupled with the QHNC equation (QHNC-MD method) for the effective interaction provides a first-principles calculation of structures of simple liquid metal: the ion-ion and electron-ion RDF's, the charge distributions of an ion and a pseudoatom, the effective ion-ion interaction and the ion-ion bridge function are evaluated in a self-consistent manner from the atomic number as the only input. We have applied this QHNC-MD method to Li, Na, K, Rb, and Cs near the melting temperature using up to 16 000 particles for the MD simulation. It is found that the convergence of the effective ion-ion interaction is fast enough for practical application to alkali metals; two MD runs are enough for convergence within accuracy of 3 to 4 digits, if the initial effective potential is properly set up. The structure factors, thus obtained, show excellent agreement with the experimental data observed by x-ray and

  7. Enhanced Stomatal Conductance by a Spontaneous Arabidopsis Tetraploid, Me-0, Results from Increased Stomatal Size and Greater Stomatal Aperture.

    PubMed

    Monda, Keina; Araki, Hiromitsu; Kuhara, Satoru; Ishigaki, Genki; Akashi, Ryo; Negi, Juntaro; Kojima, Mikiko; Sakakibara, Hitoshi; Takahashi, Sho; Hashimoto-Sugimoto, Mimi; Goto, Nobuharu; Iba, Koh

    2016-03-01

    The rate of gas exchange in plants is regulated mainly by stomatal size and density. Generally, higher densities of smaller stomata are advantageous for gas exchange; however, it is unclear what the effect of an extraordinary change in stomatal size might have on a plant's gas-exchange capacity. We investigated the stomatal responses to CO2 concentration changes among 374 Arabidopsis (Arabidopsis thaliana) ecotypes and discovered that Mechtshausen (Me-0), a natural tetraploid ecotype, has significantly larger stomata and can achieve a high stomatal conductance. We surmised that the cause of the increased stomatal conductance is tetraploidization; however, the stomatal conductance of another tetraploid accession, tetraploid Columbia (Col), was not as high as that in Me-0. One difference between these two accessions was the size of their stomatal apertures. Analyses of abscisic acid sensitivity, ion balance, and gene expression profiles suggested that physiological or genetic factors restrict the stomatal opening in tetraploid Col but not in Me-0. Our results show that Me-0 overcomes the handicap of stomatal opening that is typical for tetraploids and achieves higher stomatal conductance compared with the closely related tetraploid Col on account of larger stomatal apertures. This study provides evidence for whether larger stomatal size in tetraploids of higher plants can improve stomatal conductance. PMID:26754665

  8. Increase of larger-sized islets in C57/black mice during the long-term space flight.

    NASA Astrophysics Data System (ADS)

    Proshchina, Alexandra; Krivova, Yulia

    groups are of unequal size. The P-value was considered significant if less than 0.05. The islets in all three groups have a typical for murine pancreas architecture. The insulin-containing cells occupied the central position in pancreatic islets and the glucagon-containing cells were localized at the periphery. Histomorphometric analyses revealed significant increase of islets size in flight group compared with vivarium ground control. Moreover, the islets in group of the delayed synchronous ground control were significant larger then in group of vivarium control. No significant differences were found in islet size between flight and delayed synchronous ground control groups, but analyses indicated the increase of larger-sized islets in mice of flight group compared with synchronous control. Thus the mean islets size correlated with the body weight. The literature data indicates that similar changes are also observed in mice under conditions of an increased demand for insulin such as pregnancy, obesity, diabetes etc. According to the literature data, the researches of activity of pancreas have shown the increase of pancreatic hormones (insulin and C-peptide) in blood of astronauts in the early period after completion of space flights of various durations. In our study, the increase of islets size occurred not only in mice from flight group, but also in synchronous ground control. For this group, the live conditions imitated those of flight group without the factors of spaceflight such as microgravity. Therefore, we supposed that the hypokinesia play an important role in alteration of islets size. Thus, our data confirms the hypothesis of association microgravity and its experimental paradigms with manifestations similar to those of physical inactivity and diabetes.

  9. Does the invasive Lupinus polyphyllus increase pollinator visitation to a native herb through effects on pollinator population sizes?

    PubMed

    Jakobsson, Anna; Padrón, Benigno

    2014-01-01

    Invasive plants may compete with native species for abiotic factors as light, space and nutrients, and have also been shown to affect native pollination interactions. Studies have mainly focused on how invasive plants affect pollinator behaviour, i.e. attraction of pollinators to or away from native flowers. However, when an invasive plant provides resources utilized by native pollinators this could increase pollinator population sizes and thereby pollination success in natives. Effects mediated through changes in pollinator population sizes have been largely ignored in previous studies, and the dominance of negative interactions suggested by meta-analyses may therefore be biased. We investigated the impact of the invasive Lupinus polyphyllus on pollination in the native Lotus corniculatus using a study design comparing invaded and uninvaded sites before and after the flowering period of the invasive. We monitored wild bee abundance in transects, and visit rate and seed production of potted Lotus plants. Bumblebee abundance increased 3.9 times in invaded sites during the study period, whereas it was unaltered in uninvaded sites. Total visit rate per Lotus plant increased 2.1 times in invaded sites and decreased 4.4 times in uninvaded sites. No corresponding change in seed production of Lotus was found. The increase in visit rate to Lotus was driven by an increase in solitary bee visitation, whereas mainly bumblebees were observed to visit the invasive Lupinus. The mechanism by which the invasive increases pollinator visit rates to Lotus could be increased availability of other flower resources for solitary bees when bumblebees forage on Lupinus. PMID:24061551

  10. Demographic population model for American shad: will access to additional habitat upstream of dams increase population sizes?

    USGS Publications Warehouse

    Harris, Julianne E.; Hightower, Joseph E.

    2012-01-01

    American shad Alosa sapidissima are in decline in their native range, and modeling possible management scenarios could help guide their restoration. We developed a density-dependent, deterministic, stage-based matrix model to predict the population-level results of transporting American shad to suitable spawning habitat upstream of dams on the Roanoke River, North Carolina and Virginia. We used data on sonic-tagged adult American shad and oxytetracycline-marked American shad fry both above and below dams on the Roanoke River with information from other systems to estimate a starting population size and vital rates. We modeled the adult female population over 30 years under plausible scenarios of adult transport, effective fecundity (egg production), and survival of adults (i.e., to return to spawn the next year) and juveniles (from spawned egg to age 1). We also evaluated the potential effects of increased survival for adults and juveniles. The adult female population size in the Roanoke River was estimated to be 5,224. With no transport, the model predicted a slow population increase over the next 30 years. Predicted population increases were highest when survival was improved during the first year of life. Transport was predicted to benefit the population only if high rates of effective fecundity and juvenile survival could be achieved. Currently, transported adults and young are less likely to successfully out-migrate than individuals below the dams, and the estimated adult population size is much smaller than either of two assumed values of carrying capacity for the lower river; therefore, transport is not predicted to help restore the stock under present conditions. Research on survival rates, density-dependent processes, and the impacts of structures to increase out-migration success would improve evaluation of the potential benefits of access to additional spawning habitat for American shad.

  11. Fish oil increases raft size and membrane order of B cells accompanied by differential effects on function[S

    PubMed Central

    Rockett, Benjamin Drew; Teague, Heather; Harris, Mitchel; Melton, Mark; Williams, Justin; Wassall, Stephen R.; Shaikh, Saame Raza

    2012-01-01

    Fish oil (FO) targets lipid microdomain organization to suppress T-cell and macrophage function; however, little is known about this relationship with B cells, especially at the animal level. We previously established that a high FO dose diminished mouse B-cell lipid raft microdomain clustering induced by cross-linking GM1. To establish relevance, here we tested a FO dose modeling human intake on B-cell raft organization relative to a control. Biochemical analysis revealed more docosahexaenoic acid (DHA) incorporated into phosphatidylcholines than phosphatidylethanolamines of detergent-resistant membranes, consistent with supporting studies with model membranes. Subsequent imaging experiments demonstrated that FO increased raft size, GM1 expression, and membrane order upon cross-linking GM1 relative to no cross-linking. Comparative in vitro studies showed some biochemical differences from in vivo measurements but overall revealed that DHA, but not eicosapentaenoic acid (EPA), increased membrane order. Finally, we tested the hypothesis that disrupting rafts with FO would suppress B-cell responses ex vivo. FO enhanced LPS-induced B-cell activation but suppressed B-cell stimulation of transgenic naive CD4+ T cells. Altogether, our studies with B cells support an emerging model that FO increases raft size and membrane order accompanied by functional changes; furthermore, the results highlight differences in EPA and DHA bioactivity. PMID:22315394

  12. On the evolutionary consequences of increasing litter size with multiple paternity in wild boar (Sus scrofa scrofa).

    PubMed

    Gayet, Thibault; Devillard, Sébastien; Gamelon, Marlène; Brandt, Serge; Say, Ludovic; Baubet, Eric

    2016-06-01

    Understanding how some species may be able to evolve quickly enough to deal with anthropogenic pressure is of prime interest in evolutionary biology, conservation, and management. Wild boar (Sus scrofa scrofa) populations keep growing all over Europe despite increasing hunting pressure. In wild boar populations subject to male-selective harvesting, the initially described polygynous mating system may switch to a promiscuous/polyandrous one. Such a change in the mating system, where potentially more males sire a litter at one reproductive event, may be associated with the retention of high genetic diversity and an increase of litter size. We tested these hypotheses by estimating the number of sires per litter based on a six-year long monitoring of a wild boar population subject to particularly high harvesting pressure. Our results show a high and stable genetic diversity and high rates of multiple paternity compared to other populations, thus depicting a promiscuous/polyandrous mating system in this population. We also show that litter size is positively linked to the number of sires, suggesting that multiple paternity increases fecundity. We finally discuss that multiple paternity may be one of the factors allowing rapid evolution of this population by maintaining both genetic and phenotypic diversity. PMID:27166953

  13. Combination of PLR, MLR, MWR, and Tumor Size Could Significantly Increase the Prognostic Value for Gastrointestinal Stromal Tumors.

    PubMed

    Feng, Fan; Tian, Yangzi; Liu, Shushang; Zheng, Gaozan; Liu, Zhen; Xu, Guanghui; Guo, Man; Lian, Xiao; Fan, Daiming; Zhang, Hongwei

    2016-04-01

    combination of tumor size, MLR, PLR, and MWR could further increase the predictive value of prognosis of GISTs. PMID:27057867

  14. MicroCT and microMRI imaging of a prenatal mouse model of increased brain size

    NASA Astrophysics Data System (ADS)

    López, Elisabeth K. N.; Stock, Stuart R.; Taketo, Makoto M.; Chenn, Anjen; Ravosa, Matthew J.

    2008-08-01

    There are surprisingly few experimental models of neural growth and cranial integration. This and the dearth of information regarding fetal brain development detract from a mechanistic understanding of cranial integration and its relevance to the patterning of skull form, specifically the role of encephalization on basicranial flexion. To address this shortcoming, our research uses transgenic mice expressing a stabilized form of β-catenin to isolate the effects of relative brain size on craniofacial development. These mice develop highly enlarged brains due to an increase in neural precursors, and differences between transgenic and wild-type mice are predicted to result solely from variation in brain size. Comparisons of wild-type and transgenic mice at several prenatal ages were performed using microCT (Scanco Medical MicroCT 40) and microMRI (Avance 600 WB MR spectrometer). Statistical analyses show that the larger brain of the transgenic mice is associated with a larger neurocranium and an altered basicranial morphology. However, body size and postcranial ossification do not seem to be affected by the transgene. Comparisons of the rate of postcranial and cranial ossification using microCT also point to an unexpected effect of neural growth on skull development: increased fetal encephalization may result in a compensatory decrease in the level of cranial ossification. Therefore, if other life history factors are held constant, the ontogeny of a metabolically costly structure such as a brain may occur at the expense of other cranial structures. These analyses indicate the benefits of a multifactorial approach to cranial integration using a mouse model.

  15. Preharvest application of oxalic acid increased fruit size, bioactive compounds, and antioxidant capacity in sweet cherry cultivars (Prunus avium L.).

    PubMed

    Martínez-Esplá, Alejandra; Zapata, Pedro Javier; Valero, Daniel; García-Viguera, Cristina; Castillo, Salvador; Serrano, María

    2014-04-16

    Trees of 'Sweet Heart' and 'Sweet Late' sweet cherry cultivars (Prunus avium L.) were treated with oxalic acid (OA) at 0.5, 1.0, and 2.0 mM at 98, 112, and 126 days after full blossom. Results showed that all treatments increased fruit size at harvest, manifested by higher fruit volume and weight in cherries from treated trees than from controls, the higher effect being found with 2.0 mM OA (18 and 30% higher weight for 'Sweet Heart' and 'Sweet Late', respectively). Other quality parameters, such as color and firmness, were also increased by OA treatments, although no significant differences were found in total soluble solids or total acidity, showing that OA treatments did not affect the on-tree ripening process of sweet cherry. However, the increases in total anthocyanins, total phenolics, and antioxidant activity associated with the ripening process were higher in treated than in control cherries, leading to fruit with high bioactive compounds and antioxidant potential at commercial harvest (≅45% more anthocyanins and ≅20% more total phenolics). In addition, individual anthocyanins, flavonols, and chlorogenic acid derivatives were also increased by OA treatment. Thus, OA preharvest treatments could be an efficient and natural way to increase the quality and functional properties of sweet cherries. PMID:24684635

  16. Cucumber Mosaic Virus Movement Protein Severs Actin Filaments to Increase the Plasmodesmal Size Exclusion Limit in Tobacco[W][OA

    PubMed Central

    Su, Shengzhong; Liu, Zhaohui; Chen, Cheng; Zhang, Yan; Wang, Xu; Zhu, Lei; Miao, Long; Wang, Xue-Chen; Yuan, Ming

    2010-01-01

    Plant viral movement proteins (MPs) enable viruses to pass through cell walls by increasing the size exclusion limit (SEL) of plasmodesmata (PD). Here, we report that the ability of Cucumber mosaic virus (CMV) MP to increase the SEL of the PD could be inhibited by treatment with the actin filament (F-actin)–stabilizing agent phalloidin but not by treatment with the F-actin–destabilizing agent latrunculin A. In vitro studies showed that CMV MP bound globular and F-actin, inhibited actin polymerization, severed F-actin, and participated in plus end capping of F-actin. Analyses of two CMV MP mutants, one with and one without F-actin severing activities, demonstrated that the F-actin severing ability was required to increase the PD SEL. Furthermore, the Tobacco mosaic virus MP also exhibited F-actin severing activity, and its ability to increase the PD SEL was inhibited by treatment with phalloidin. Our data provide evidence to support the hypothesis that F-actin severing is required for MP-induced increase in the SEL of PD. This may have broad implications in the study of the mechanisms of actin dynamics that regulate cell-to-cell transport of viral and endogenous proteins. PMID:20435906

  17. Increased size and cellularity of advanced atherosclerotic lesions in mice with endothelial overexpression of the human TRPC3 channel

    PubMed Central

    Smedlund, Kathryn B.; Birnbaumer, Lutz; Vazquez, Guillermo

    2015-01-01

    In previous in vitro studies, we showed that Transient Receptor Potential Canonical 3 (TRPC3), a calcium-permeable, nonselective cation channel endowed with high constitutive function, is an obligatory component of the inflammatory signaling that controls expression of the vascular cell adhesion molecule-1 (VCAM-1) and monocyte adhesion to coronary artery endothelial cells. Also, TRPC3 expression in these cells was found to be up-regulated by proatherogenic factors, which enhanced inflammation and VCAM-1 expression. However, it remained to be determined whether these in vitro findings were of relevance to atherosclerotic lesion development in vivo. To answer this important question in the present work, we generated mice with endothelial-specific overexpression of human TRPC3 in an Apoe knockout background (TgEST3ApoeKO) and examined lesions in the aortic sinus following 10 and 16 wk on a high-fat diet. No significant differences were found in size or complexity of early stage lesions (10 wk). However, advanced plaques (16 wk) from TgEST3ApoeKO mice exhibited a significant increase in size and macrophage content compared with nontransgenic littermate controls. Remarkably, this change was correlated with increased VCAM-1 and phospho-IkBα immunoreactivity along the endothelial lining of lesions from transgenic animals compared with controls. These findings validate the in vivo relevance of previous in vitro findings and represent, to our knowledge, the first in vivo evidence for a proatherogenic role of endothelial TRPC3. PMID:25870279

  18. Selective-field-ionization dynamics of a lithium m=2 Rydberg state: Landau-Zener model versus quantal approach

    SciTech Connect

    Foerre, M.; Hansen, J.P.

    2003-05-01

    The selective-field-ionization (SFI) dynamics of a Rydberg state of lithium with magnetic quantum number m=2 is studied in detail based on two different theoretical models: (1) a close coupling integration of the Schroedinger equation and (2) the multichannel (incoherent) Landau-Zener (MLZ) model. The m=2 states are particularly interesting, since they define a border zone between fully adiabatic (m=0,1) and fully diabatic (m>2) ionization dynamics. Both sets of calculations are performed up to, and above, the classical ionization limit. It is found that the MLZ model is excellent in the description of the fully diabatic dynamics while certain discrepancies between the time dependent quantal amplitudes appear when the dynamics become involved. Thus, in this region, the analysis of experimental SFI spectra should be performed with care.

  19. Diabetes Increases Cryoinjury Size with Associated Effects on Cx43 Gap Junction Function and Phosphorylation in the Mouse Heart.

    PubMed

    Palatinus, Joseph A; Gourdie, Robert G

    2016-01-01

    Diabetic patients develop larger myocardial infarctions and have an increased risk of death following a heart attack. The poor response to myocardial injury in the diabetic heart is likely related to the many metabolic derangements from diabetes that create a poor substrate in general for wound healing, response to injury and infection. Studies in rodents have implicated a role for the gap junction protein connexin 43 (Cx43) in regulating the injury response in diabetic skin wounds. In this study, we sought to determine whether diabetes alters Cx43 molecular interactions or intracellular communication in the cryoinjured STZ type I diabetic mouse heart. We found that epicardial cryoinjury size is increased in diabetic mice and this increase is prevented by preinjury insulin administration. Consistent with these findings, we found that intercellular coupling via gap junctions is decreased after insulin administration in diabetic and nondiabetic mice. This decrease in coupling is associated with a concomitant increase in phosphorylation of Cx43 at serine 368, a residue known to decrease channel conductance. Taken together, our results suggest that insulin regulates both gap junction-mediated intercellular communication and injury propagation in the mouse heart. PMID:27034963

  20. Diabetes Increases Cryoinjury Size with Associated Effects on Cx43 Gap Junction Function and Phosphorylation in the Mouse Heart

    PubMed Central

    Palatinus, Joseph A.; Gourdie, Robert G.

    2016-01-01

    Diabetic patients develop larger myocardial infarctions and have an increased risk of death following a heart attack. The poor response to myocardial injury in the diabetic heart is likely related to the many metabolic derangements from diabetes that create a poor substrate in general for wound healing, response to injury and infection. Studies in rodents have implicated a role for the gap junction protein connexin 43 (Cx43) in regulating the injury response in diabetic skin wounds. In this study, we sought to determine whether diabetes alters Cx43 molecular interactions or intracellular communication in the cryoinjured STZ type I diabetic mouse heart. We found that epicardial cryoinjury size is increased in diabetic mice and this increase is prevented by preinjury insulin administration. Consistent with these findings, we found that intercellular coupling via gap junctions is decreased after insulin administration in diabetic and nondiabetic mice. This decrease in coupling is associated with a concomitant increase in phosphorylation of Cx43 at serine 368, a residue known to decrease channel conductance. Taken together, our results suggest that insulin regulates both gap junction-mediated intercellular communication and injury propagation in the mouse heart. PMID:27034963

  1. Apolipoprotein M expression increases the size of nascent pre beta HDL formed by ATP binding cassette transporter A1.

    PubMed

    Mulya, Anny; Seo, Jeongmin; Brown, Amanda L; Gebre, Abraham K; Boudyguina, Elena; Shelness, Gregory S; Parks, John S

    2010-03-01

    Apolipoprotein M (apoM) is a novel apolipoprotein that is reportedly necessary for pre beta HDL formation; however, its detailed function remains unknown. We investigated the biogenesis and properties of apoM and its effects on the initial steps of nascent pre beta HDL assembly by ABCA1 in HEK293 cells. Transiently transfected apoM was localized primarily in the endomembrane compartment. Pulse-chase analyses demonstrated that apoM is inefficiently secreted, relative to human serum albumin, and that approximately 50% remains membrane-associated after extraction with sodium carbonate, pH 11.5. To investigate the role of apoM in nascent pre beta HDL formation, ABCA1-expressing or control cells, transfected with empty vector, apoM, or C-terminal epitope-tagged apoM (apoM-C-FLAG), were incubated with (125)I-apoA-I for 24 h. Conditioned media were harvested and fractionated by fast-protein liquid chromatography (FPLC) to monitor HDL particle size. Pre beta HDL particles were formed effectively in the absence of apoM expression; however, increased apoM expression stimulated the formation of larger-sized nascent pre beta HDLs. Immunoprecipitation with anti-apoA-I antibody followed by apoM Western blot analysis revealed that little secreted apoM was physically associated with pre beta HDL. Our results suggest that apoM is an atypical secretory protein that is not necessary for ABCA1-dependent pre beta HDL formation but does stimulate the formation of larger-sized pre beta HDL. We propose that apoM may function catalytically at an intracellular site to transfer lipid onto pre beta HDL during or after their formation by ABCA1. PMID:19767535

  2. Reduction of the neuroprotective transcription factor Npas4 results in increased neuronal necrosis, inflammation and brain lesion size following ischaemia.

    PubMed

    Choy, Fong Chan; Klarić, Thomas S; Leong, Wai Khay; Koblar, Simon A; Lewis, Martin D

    2016-08-01

    Stroke is the second leading cause of death and the most frequent cause of adult disability. Neuronal Per-Arnt-Sim domain protein 4 (Npas4) is an activity-dependent transcription factor whose expression is induced in various brain insults, including cerebral ischaemia. Although previous studies have demonstrated that Npas4 plays a critical role in protecting neurons against neurodegenerative insults, the neuroprotective effect of Npas4 in response to ischaemic brain injury remains unknown. In this study, we used a loss-of-function approach to examine the neuroprotective potential of Npas4 in the context of ischaemic damage. Using oxygen and glucose deprivation, we demonstrated that the knockdown of Npas4 in mouse cortical neurons resulted in increased susceptibility to cell death. The protective effect of Npas4 was further investigated in vivo using a photochemically-induced stroke model in mice. We found a significantly larger lesion size and increased neurodegeneration in Npas4 knockout mice as compared to wild-type mice. Moreover, we also showed that ablation of Npas4 caused an increase in activated astrocytes and microglia, pro-inflammatory cytokines interleukin-6 and tumour necrosis factor alpha levels and a switch from apoptotic to necrotic cell death. Taken together, these data suggest that Npas4 plays a neuroprotective role in ischaemic stroke by limiting progressive neurodegeneration and neuroinflammation. PMID:26661154

  3. Translocation of differently sized and charged polystyrene nanoparticles in in vitro intestinal cell models of increasing complexity.

    PubMed

    Walczak, Agata P; Kramer, Evelien; Hendriksen, Peter J M; Tromp, Peter; Helsper, Johannes P F G; van der Zande, Meike; Rietjens, Ivonne M C M; Bouwmeester, Hans

    2015-05-01

    Intestinal translocation is a key factor for determining bioavailability of nanoparticles (NPs) after oral uptake. Therefore, we evaluated three in vitro intestinal cell models of increasing complexity which might affect the translocation of NPs: a mono-culture (Caco-2 cells), a co-culture with mucus secreting HT29-MTX cells and a tri-culture with M-cells. Cell models were exposed to well characterized differently sized (50 and 100 nm) and charged (neutral, positively and negatively) polystyrene NPs. In addition, two types of negatively charged NPs with different surface chemistries were used. Size strongly affected the translocation of NPs, ranging up to 7.8% for the 50 nm NPs and 0.8% for the 100 nm NPs. Surface charge of NPs affected the translocation, however, surface chemistry seems more important, as the two types of negatively charged 50 nm NPs had an over 30-fold difference in translocation. Compared with the Caco-2 mono-culture, presence of mucus significantly reduced the translocation of neutral 50 nm NPs, but significantly increased the translocation of one type of negatively charged NPs. Incorporation of M-cells shifted the translocation rates for both NPs closer to those in the mono-culture model. The relative pattern of NP translocation in all three models was similar, but the absolute amounts of translocated NPs differed per model. We conclude that for comparing the relative translocation of different NPs, using one intestinal model is sufficient. To choose the most representative model for risk assessment, in vivo experiments are now needed to determine the in vivo translocation rates of the used NPs. PMID:25093449

  4. Increased left atrial size is associated with reduced atrial stiffness and preserved reservoir function in athlete's heart.

    PubMed

    D'Ascenzi, Flavio; Pelliccia, Antonio; Natali, Benedetta Maria; Cameli, Matteo; Andrei, Valentina; Incampo, Eufemia; Alvino, Federico; Lisi, Matteo; Padeletti, Margherita; Focardi, Marta; Bonifazi, Marco; Mondillo, Sergio

    2015-04-01

    Left atrial (LA) fibrosis with increased stiffness has been assumed to be the substrates for occurrence of atrial arrhythmias in athletes. However, this hypothesis has not yet been confirmed in humans. Aim of this study was, therefore, to assess LA remodeling and stiffness in competitive athletes. 150 competitive athletes and 90 age and sex-matched sedentary subjects were analyzed by speckle-tracking echocardiography to measure peak atrial longitudinal strain (PALS) and peak atrial contraction strain (PACS). LA stiffness was determined using E/e' ratio in conjunction with PALS. Left ventricular (LV) stiffness was also calculated. LA volume index was greater in athletes as compared with controls (24.6 ± 7.3 vs. 18.4 ± 7.8 mL/m(2), p < .0001). LA PALS, LA PACS, and E/e' ratio were lower in athletes in comparison with controls (p < .05, p ≤ .001, and p < .0001, respectively). Despite greater LA size, competitive athletes had lower LA stiffness as compared with controls (0.13 ± 0.04 vs. 0.16 ± 0.06, p ≤ .001). In addition, LV stiffness was lower in athletes (0.84 ± 0.27 vs. 1.07 ± 0.46, p ≤ .001). The only independent predictor of LA stiffness was LV stiffness (β = 0.46, p < .0001), while the only independent predictor of LA volume index was LV end-systolic volume index (β = 0.25, p = .002). Competitive athletes showed greater LA size associated with lower stiffness as compared with controls. Thus, LA remodeling in the context of the athlete's heart is not associated with increased LA stiffness. These findings support the benign nature of LA remodeling in athletes, occurring as a physiological adaptation to exercise conditioning. PMID:25627780

  5. A natural antipredation experiment: predator control and reduced sea ice increases colony size in a long-lived duck

    PubMed Central

    Hanssen, Sveinn A; Moe, Børge; Bårdsen, Bård-Jørgen; Hanssen, Frank; Gabrielsen, Geir W

    2013-01-01

    Anthropogenic impact on the environment and wildlife are multifaceted and far-reaching. On a smaller scale, controlling for predators has been increasing the yield from local natural prey resources. Globally, human-induced global warming is expected to impose severe negative effects on ecosystems, an effect that is expected to be even more pronounced in the scarcely populated northern latitudes. The clearest indication of a changing Arctic climate is an increase in both air and ocean temperatures leading to reduced sea ice distribution. Population viability is for long-lived species dependent on adult survival and recruitment. Predation is the main mortality cause in many bird populations, and egg predation is considered the main cause of reproductive failure in many birds. To assess the effect of predation and climate, we compared population time series from a natural experiment where a trapper/down collector has been licensed to actively protect breeding common eiders Somateria mollissima (a large seaduck) by shooting/chasing egg predators, with time series from another eider colony located within a nature reserve with no manipulation of egg predators. We found that actively limiting predator activity led to an increase in the population growth rate and carrying capacity with a factor of 3–4 compared to that found in the control population. We also found that population numbers were higher in years with reduced concentration of spring sea ice. We conclude that there was a large positive impact of human limitation of egg predators, and that this lead to higher population growth rate and a large increase in size of the breeding colony. We also report a positive effect of warming climate in the high arctic as reduced sea-ice concentrations was associated with higher numbers of breeding birds. PMID:24223290

  6. Transgenic Tobacco Overexpressing Brassica juncea HMG-CoA Synthase 1 Shows Increased Plant Growth, Pod Size and Seed Yield

    PubMed Central

    Liao, Pan; Wang, Hui; Wang, Mingfu; Hsiao, An-Shan; Bach, Thomas J.; Chye, Mee-Len

    2014-01-01

    Seeds are very important not only in the life cycle of the plant but they represent food sources for man and animals. We report herein a mutant of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS), the second enzyme in the mevalonate (MVA) pathway that can improve seed yield when overexpressed in a phylogenetically distant species. In Brassica juncea, the characterisation of four isogenes encoding HMGS has been previously reported. Enzyme kinetics on recombinant wild-type (wt) and mutant BjHMGS1 had revealed that S359A displayed a 10-fold higher enzyme activity. The overexpression of wt and mutant (S359A) BjHMGS1 in Arabidopsis had up-regulated several genes in sterol biosynthesis, increasing sterol content. To quickly assess the effects of BjHMGS1 overexpression in a phylogenetically more distant species beyond the Brassicaceae, wt and mutant (S359A) BjHMGS1 were expressed in tobacco (Nicotiana tabacum L. cv. Xanthi) of the family Solanaceae. New observations on tobacco OEs not previously reported for Arabidopsis OEs included: (i) phenotypic changes in enhanced plant growth, pod size and seed yield (more significant in OE-S359A than OE-wtBjHMGS1) in comparison to vector-transformed tobacco, (ii) higher NtSQS expression and sterol content in OE-S359A than OE-wtBjHMGS1 corresponding to greater increase in growth and seed yield, and (iii) induction of NtIPPI2 and NtGGPPS2 and downregulation of NtIPPI1, NtGGPPS1, NtGGPPS3 and NtGGPPS4. Resembling Arabidopsis HMGS-OEs, tobacco HMGS-OEs displayed an enhanced expression of NtHMGR1, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Overall, increased growth, pod size and seed yield in tobacco HMGS-OEs were attributed to the up-regulation of native NtHMGR1, NtIPPI2, NtSQS, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Hence, S359A has potential in agriculture not only in improving phytosterol content but also seed yield, which may be desirable in food crops. This work further demonstrates HMGS function in plant reproduction

  7. Transgenic tobacco overexpressing Brassica juncea HMG-CoA synthase 1 shows increased plant growth, pod size and seed yield.

    PubMed

    Liao, Pan; Wang, Hui; Wang, Mingfu; Hsiao, An-Shan; Bach, Thomas J; Chye, Mee-Len

    2014-01-01

    Seeds are very important not only in the life cycle of the plant but they represent food sources for man and animals. We report herein a mutant of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS), the second enzyme in the mevalonate (MVA) pathway that can improve seed yield when overexpressed in a phylogenetically distant species. In Brassica juncea, the characterisation of four isogenes encoding HMGS has been previously reported. Enzyme kinetics on recombinant wild-type (wt) and mutant BjHMGS1 had revealed that S359A displayed a 10-fold higher enzyme activity. The overexpression of wt and mutant (S359A) BjHMGS1 in Arabidopsis had up-regulated several genes in sterol biosynthesis, increasing sterol content. To quickly assess the effects of BjHMGS1 overexpression in a phylogenetically more distant species beyond the Brassicaceae, wt and mutant (S359A) BjHMGS1 were expressed in tobacco (Nicotiana tabacum L. cv. Xanthi) of the family Solanaceae. New observations on tobacco OEs not previously reported for Arabidopsis OEs included: (i) phenotypic changes in enhanced plant growth, pod size and seed yield (more significant in OE-S359A than OE-wtBjHMGS1) in comparison to vector-transformed tobacco, (ii) higher NtSQS expression and sterol content in OE-S359A than OE-wtBjHMGS1 corresponding to greater increase in growth and seed yield, and (iii) induction of NtIPPI2 and NtGGPPS2 and downregulation of NtIPPI1, NtGGPPS1, NtGGPPS3 and NtGGPPS4. Resembling Arabidopsis HMGS-OEs, tobacco HMGS-OEs displayed an enhanced expression of NtHMGR1, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Overall, increased growth, pod size and seed yield in tobacco HMGS-OEs were attributed to the up-regulation of native NtHMGR1, NtIPPI2, NtSQS, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Hence, S359A has potential in agriculture not only in improving phytosterol content but also seed yield, which may be desirable in food crops. This work further demonstrates HMGS function in plant reproduction

  8. L-Phosphinothricin modulation of inwardly rectifying K(+) channels increased excitability in striatal medium-sized spiny neurons.

    PubMed

    Domingos, Laetitia; Desrus, Agnès; Même, Sandra; Même, William

    2016-07-01

    Phosphinotricin (L-PPT) is the active compound of a broad-spectrum herbicide. Acute poisoning with L-PPT has various clinical manifestations, including seizures and convulsions. However, the exact mechanism of L-PPT toxicity remains unclear. The present study addressed the role of L-PPT, in the excitability of striatal medium-sized spiny neurons (MSNs). In whole-cell current-clamp experiments, L-PPT increased the input resistance (Ri), decreased the rheobase and increased the firing frequency of action potentials. In voltage-clamp experiments, L-PPT inhibited the inward-rectifying potassium (Kir) currents. Finally, the effects of L-PPT mimicked the inhibition of Kir channels with Ba(2+) on neuronal excitability. Altogether, these results suggest that the herbicide L-PPT is a modulator of Kir channels in MSNs. Thereby, Kir channels are potent regulators of the excitability of MSNs and reduced open probability of these channels would generate a powerful upregulation of neuronal output. This effect may represent a possible mechanism for L-PPT dependent neuronal toxicity. PMID:27136897

  9. Warring arthropod societies: Social spider colonies can delay annihilation by predatory ants via reduced apparency and increased group size.

    PubMed

    Keiser, Carl N; Wright, Colin M; Pruitt, Jonathan N

    2015-10-01

    Sociality provides individuals with benefits via collective foraging and anti-predator defense. One of the costs of living in large groups, however, is increased apparency to natural enemies. Here, we test how the individual-level and collective traits of spider societies can increase the risk of discovery and death by predatory ants. We transplanted colonies of the social spider Stegodyphus dumicola into a habitat dense with one of their top predators, the pugnacious ant Anoplolepis custodiens. With three different experiments, we test how colony-wide survivorship in a predator-dense habitat can be altered by colony apparency (i.e., the presence of a capture web), group size, and group composition (i.e., the proportion of bold and shy personality types present). We also test how spiders' social context (i.e., living solitarily vs. among conspecifics) modifies their behaviour toward ants in their capture web. Colonies with capture webs intact were discovered by predatory ants on average 25% faster than colonies with the capture web removed, and all discovered colonies eventually collapsed and succumbed to predation. However, the lag time from discovery by ants to colony collapse was greater for colonies containing more individuals. The composition of individual personality types in the group had no influence on survivorship. Spiders in a social group were more likely to approach ants caught in their web than were isolated spiders. Isolated spiders were more likely to attack a safe prey item (a moth) than they were to attack ants and were more likely to retreat from ants after contact than they were after contact with moths. Together, our data suggest that the physical structures produced by large animal societies can increase their apparency to natural enemies, though larger groups can facilitate a longer lag time between discovery and demise. Lastly, the interaction between spiders and predatory ants seems to depend on the social context in which spiders reside

  10. Slip-weakening zone sizes at nucleation of catastrophic subaerial and submarine landslides by gradually increasing pore pressure

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.; Rice, J. R.

    2011-12-01

    We address the nucleation of dynamic landslide rupture in response to gradual pore pressure increases. Nucleation marks the onset of acceleration of the overlying slope mass due to the suddenly rapid enlargement of a sub-surface zone of shear failure, previously deforming quasi-statically. We model that zone as a planar surface undergoing initially linear slip-weakening frictional failure within a bordering linear-elastic medium. The results are also relevant to earthquake nucleation. The sub-surface rupture zone considered runs parallel to the free surface of a uniform slope, under a 2D plane-strain deformation state. We show results for ruptures with friction coefficients following linear slip weakening (i.e., the residual friction is not yet reached). For spatially broad increases in pore pressure, the nucleation length depends on a ratio of depth to a cohesive zone length scale. In the very broad-increase limit, a direct numerical solution for nucleation lengths compares well with solutions to a corresponding eigenvalue problem (similar to Uenishi and Rice [JGR '03]), in which spatial variations in normal stress are neglected. We estimate nucleation lengths for subaerial and submarine conditions using data [e.g., Bishop et al., Géotech. '71; Stark et al., JGGE '05] from ring-shear tests on sediments (peak friction fp = 0.5, frictional slip-weakening rate within the range w = -df/d(slip) = 0.1/cm-1/cm). We assume that only pre-stresses, and not material properties, vary with depth. With such fp and w, we find for a range of subsurface depths and shear moduli μ that nucleation lengths are typically several hundred meters long for shallow undersea slopes, and up to an order of magnitude less for steeper slopes on the Earth's surface. In the submarine case, this puts nucleation lengths in a size range comparable to observed pore-pressure-generated seafloor disturbances as pockmarks [e.g., Gay et al., MG '06].

  11. Multiple nanosecond electric pulses increase the number but not the size of long-lived nanopores in the cell membrane.

    PubMed

    Pakhomov, Andrei G; Gianulis, Elena; Vernier, P Thomas; Semenov, Iurii; Xiao, Shu; Pakhomova, Olga N

    2015-04-01

    Exposure to intense, nanosecond-duration electric pulses (nsEP) opens small but long-lived pores in the plasma membrane. We quantified the cell uptake of two membrane integrity marker dyes, YO-PRO-1 (YP) and propidium (Pr) in order to test whether the pore size is affected by the number of nsEP. The fluorescence of the dyes was calibrated against their concentrations by confocal imaging of stained homogenates of the cells. The calibrations revealed a two-phase dependence of Pr emission on the concentration (with a slower rise at<4μM) and a linear dependence for YP. CHO cells were exposed to nsEP trains (1 to 100 pulses, 60ns, 13.2kV/cm, 10Hz) with Pr and YP in the medium, and the uptake of the dyes was monitored by time-lapse imaging for 3min. Even a single nsEP triggered a modest but detectable entry of both dyes, which increased linearly when more pulses were applied. The influx of Pr per pulse was constant and independent of the pulse number. The influx of YP per pulse was highest with 1- and 2-pulse exposures, decreasing to about twice the Pr level for trains from 5 to 100 pulses. The constant YP/Pr influx ratio for trains of 5 to 100 pulses suggests that increasing the number of pulses permeabilizes cells to a greater extent by increasing the pore number and not the pore diameter. PMID:25585279

  12. Excess Salt Increases Infarct Size Produced by Photothrombotic Distal Middle Cerebral Artery Occlusion in Spontaneously Hypertensive Rats

    PubMed Central

    Yao, Hiroshi; Nabika, Toru

    2014-01-01

    Cerebral circulation is known to be vulnerable to high salt loading. However, no study has investigated the effects of excess salt on focal ischemic brain injury. After 14 days of salt loading (0.9% saline) or water, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) were subjected to photothrombotic middle cerebral artery occlusion (MCAO), and infarct volume was determined at 48 h after MCAO: albumin and hemoglobin contents in discrete brain regions were also determined in SHR. Salt loading did not affect blood pressure levels in SHR and WKY. After MCAO, regional cerebral blood flow (CBF), determined with two ways of laser-Doppler flowmetry (one-point measurement or manual scanning), was more steeply decreased in the salt-loaded group than in the control group. In SHR/Izm, infarct volume in the salt-loaded group was 112±27 mm3, which was significantly larger than 77±12 mm3 in the control group (p = 0.002), while the extents of blood-brain barrier disruption (brain albumin and hemoglobin levels) were not affected by excess salt. In WKY, salt loading did not significantly increase infarct size. These results show the detrimental effects of salt loading on intra-ischemic CBF and subsequent brain infarction produced by phototrhombotic MCAO in hypertensive rats. PMID:24816928

  13. When larger brains do not have more neurons: increased numbers of cells are compensated by decreased average cell size across mouse individuals

    PubMed Central

    Herculano-Houzel, Suzana; Messeder, Débora J.; Fonseca-Azevedo, Karina; Pantoja, Nilma A.

    2015-01-01

    There is a strong trend toward increased brain size in mammalian evolution, with larger brains composed of more and larger neurons than smaller brains across species within each mammalian order. Does the evolution of increased numbers of brain neurons, and thus larger brain size, occur simply through the selection of individuals with more and larger neurons, and thus larger brains, within a population? That is, do individuals with larger brains also have more, and larger, neurons than individuals with smaller brains, such that allometric relationships across species are simply an extension of intraspecific scaling? Here we show that this is not the case across adult male mice of a similar age. Rather, increased numbers of neurons across individuals are accompanied by increased numbers of other cells and smaller average cell size of both types, in a trade-off that explains how increased brain mass does not necessarily ensue. Fundamental regulatory mechanisms thus must exist that tie numbers of neurons to numbers of other cells and to average cell size within individual brains. Finally, our results indicate that changes in brain size in evolution are not an extension of individual variation in numbers of neurons, but rather occur through step changes that must simultaneously increase numbers of neurons and cause cell size to increase, rather than decrease. PMID:26082686

  14. Quantal Study of the Exchange Reaction for N + N2 using an ab initio Potential Energy Surface

    NASA Technical Reports Server (NTRS)

    Wang, Dunyou; Stallcop, James R.; Huo, Winifred M.; Dateo, Christopher E.; Schwenke, David W.; Partridge, Harry; Kwak, Dochan (Technical Monitor)

    2002-01-01

    The N + N2 exchange rate is calculated using a time-dependent quantum dynamics method on a newly determined ab initio potential energy surface (PES) for the ground A" state. This ab initio PES shows a double barrier feature in the interaction region with the barrier height at 47.2 kcal/mol, and a shallow well between these two barriers, with the minimum at 43.7 kcal/mol. A quantum dynamics wave packet calculation has been carried out using the fitted PES to compute the cumulative reaction probability for the exchange reaction of N + N2(J=O). The J - K shift method is then employed to obtain the rate constant for this reaction. The calculated rate constant is compared with experimental data and a recent quasi-classical calculation using a LEPS PES. Significant differences are found between the present and quasiclassical results. The present rate calculation is the first accurate 3D quantal dynamics study for N + N2 reaction system and the ab initio PES reported here is the first such surface for N3.

  15. A myostatin inhibitor (propeptide-Fc) increases muscle mass and muscle fiber size in aged mice but does not increase bone density or bone strength.

    PubMed

    Arounleut, Phonepasong; Bialek, Peter; Liang, Li-Fang; Upadhyay, Sunil; Fulzele, Sadanand; Johnson, Maribeth; Elsalanty, Mohammed; Isales, Carlos M; Hamrick, Mark W

    2013-09-01

    Loss of muscle and bone mass with age are significant contributors to falls and fractures among the elderly. Myostatin deficiency is associated with increased muscle mass in mice, dogs, cows, sheep and humans, and mice lacking myostatin have been observed to show increased bone density in the limb, spine, and jaw. Transgenic overexpression of myostatin propeptide, which binds to and inhibits the active myostatin ligand, also increases muscle mass and bone density in mice. We therefore sought to test the hypothesis that in vivo inhibition of myostatin using an injectable myostatin propeptide (GDF8 propeptide-Fc) would increase both muscle mass and bone density in aged (24 mo) mice. Male mice were injected weekly (20 mg/kg body weight) with recombinant myostatin propeptide-Fc (PRO) or vehicle (VEH; saline) for four weeks. There was no difference in body weight between the two groups at the end of the treatment period, but PRO treatment significantly increased mass of the tibialis anterior muscle (+ 7%) and increased muscle fiber diameter of the extensor digitorum longus (+ 16%) and soleus (+ 6%) muscles compared to VEH treatment. Bone volume relative to total volume (BV/TV) of the femur calculated by microCT did not differ significantly between PRO- and VEH-treated mice, and ultimate force (Fu), stiffness (S), toughness (U) measured from three-point bending tests also did not differ significantly between groups. Histomorphometric assays also revealed no differences in bone formation or resorption in response to PRO treatment. These data suggest that while developmental perturbation of myostatin signaling through either gene knockout or transgenic inhibition may alter both muscle and bone mass in mice, pharmacological inhibition of myostatin in aged mice has a more pronounced effect on skeletal muscle than on bone. PMID:23832079

  16. Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity

    PubMed Central

    Payne, Jonathan L.; Boyer, Alison G.; Brown, James H.; Finnegan, Seth; Kowalewski, Michał; Krause, Richard A.; Lyons, S. Kathleen; McClain, Craig R.; McShea, Daniel W.; Novack-Gottshall, Philip M.; Smith, Felisa A.; Stempien, Jennifer A.; Wang, Steve C.

    2009-01-01

    The maximum size of organisms has increased enormously since the initial appearance of life >3.5 billion years ago (Gya), but the pattern and timing of this size increase is poorly known. Consequently, controls underlying the size spectrum of the global biota have been difficult to evaluate. Our period-level compilation of the largest known fossil organisms demonstrates that maximum size increased by 16 orders of magnitude since life first appeared in the fossil record. The great majority of the increase is accounted for by 2 discrete steps of approximately equal magnitude: the first in the middle of the Paleoproterozoic Era (≈1.9 Gya) and the second during the late Neoproterozoic and early Paleozoic eras (0.6–0.45 Gya). Each size step required a major innovation in organismal complexity—first the eukaryotic cell and later eukaryotic multicellularity. These size steps coincide with, or slightly postdate, increases in the concentration of atmospheric oxygen, suggesting latent evolutionary potential was realized soon after environmental limitations were removed. PMID:19106296

  17. LETTER TO THE EDITOR: The validity of classical trajectory and perturbative quantal methods for electron-impact ionization from excited states in H-like ions

    NASA Astrophysics Data System (ADS)

    Griffin, D. C.; Ballance, C. P.; Pindzola, M. S.; Robicheaux, F.; Loch, S. D.; Ludlow, J. A.; Witthoeft, M. C.; Colgan, J.; Fontes, C. J.; Schultz, D. R.

    2005-06-01

    To test the validity of classical trajectory and perturbative quantal methods for electron-impact ionization of H-like ions from excited states, we have performed advanced close-coupling calculations of ionization from excited states in H, Li2+ and B4+ using the R-matrix with pseudo states and the time-dependent close-coupling methods. Comparisons with our classical trajectory Monte Carlo (CTMC) and distorted-wave (DW) calculations show that the CTMC method is more accurate than the DW method for H, but does not improve with n and grows substantially worse with Z, while the DW method improves with Z and grows worse with n.

  18. Histomorphology of the bottlenose dolphin (Tursiops truncatus) pancreas and association of increasing islet β-cell size with chronic hypercholesterolemia.

    PubMed

    Colegrove, Kathleen M; Venn-Watson, Stephanie

    2015-04-01

    Bottlenose dolphins (Tursiops truncatus) can develop metabolic states mimicking prediabetes, including hyperinsulinemia, hyperlipidemia, elevated glucose, and fatty liver disease. Little is known, however, about dolphin pancreatic histomorphology. Distribution and area of islets, α, β, and δ cells were evaluated in pancreatic tissue from 22 dolphins (mean age 25.7years, range 0-51). Associations of these measurements were evaluated by sex, age, percent high glucose and lipids during the last year of life, and presence or absence of fatty liver disease and islet cell vacuolation. The most common pancreatic lesions identified were exocrine pancreas fibrosis (63.6%) and mild islet cell vacuolation (47.4%); there was no evidence of insulitis or amyloid deposition, changes commonly associated with type 2 diabetes. Dolphin islet architecture appears to be most similar to the pig, where α and β cells are localized to the central or periphery of the islet, respectively, or are well dispersed throughout the islet. Unlike pigs, large islets (greater than 10,000μm(2)) were common in dolphins, similar to that found in humans. A positive linear association was identified between dolphin age and islet area average, supporting a compensatory response similar to other species. The strongest finding in this study was a positive linear association between islet size, specifically β-cells, and percent blood samples with high cholesterol (greater than 280mg/dl, R(2)=0.57). This study is the most comprehensive assessment of the dolphin pancreas to date and may help direct future studies, including associations between chronic hypercholesterolemia and β-cell size. PMID:25745813

  19. Species near its equilibrium size in a fluctuating environment can evolve a lower intrinsic rate of increase

    SciTech Connect

    Heckel, D.G.; Roughgarden, J.

    1980-12-01

    In one specific model of a density-regulated population undergoing natural selection in a fluctuating environment there is a systematic evolutionary pressure favoring a lower intrinsic rate of increase, which can sometimes even overcome an evolutionary pressure favoring a higher carrying capacity.

  20. Visible-light absorption in 2D covalent triazine framework: enhanced by interlayer coupling and pore size increasing

    NASA Astrophysics Data System (ADS)

    Jiang, Xue; Zhao, Jijun; Dalian University of Technology Collaboration

    2014-03-01

    Compared with traditional bulk materials, two-dimensional (2D) crystals have some intrinsic advantages as photocatalysis owing to the limited thickness and large surface area. So far, many monolayer materials have been shown to be potential photocatalysis for water splitting from both theoretical calculations and experiments; while most of them are inorganic materials. In contrast, g-carbon nitride, as a starting successful case, motivates us to explore 2D organic semiconductors, which have not yet well investigated. Using first principles calculations, we predicted a family of 2D covalent triazine framework (CTF) as a promising visible-light-driven photocatalyst by studying their electronic structures, work function, CBM/VBM position, and optical absorption spectra. Moreover, we found that multilayer CTF have much better visible-light adsorption than a single layer induced by the interlayer coupling. In addition, controlled construction of such CTF from suitable organic subunit pave the way for connection between the optical energy gap of CTF and pore size. The insights from our study not only enrich the family of organic semiconductor photocatalyst, but also are very helpful in designing and assembling CTF subunits for optimal performance.

  1. Planning and Delivering Instruction with Increasing Class Sizes in Educational Administration Program Coursework: Modeling Leadership Skills for New Professors Transitioning from K-12 Administration

    ERIC Educational Resources Information Center

    Stebbins, Gary

    2009-01-01

    Increased class sizes and advising responsibilities are the new realities in California's graduate programs of Educational Administration. In order to effectively meet new challenges, professors must make adjustments in venue, plan meticulously, utilize technology, distribute leadership, and implement alternative grading systems. This is a…

  2. Electromagnetic Transponders Indicate Prostate Size Increase Followed by Decrease During the Course of External Beam Radiation Therapy

    SciTech Connect

    King, Benjamin L.; Butler, Wayne M.; Merrick, Gregory S.; Kurko, Brian S.; Reed, Joshua L.; Murray, Brian C.; Wallner, Kent E.

    2011-04-01

    Purpose: Real-time image guidance enables more accurate radiation therapy by tracking target movement. This study used transponder positions to monitor changes in prostate volume that may be a source of dosimetric and target inaccuracy. Methods and Materials: Twenty-four men with biopsy-proven T1c-T3a prostate cancer each had three electromagnetic transponders implanted transperineally. Their coordinates were recorded by the Calypso system, and the perimeter of the triangle formed by the transponders was used to calculate prostate volumes at sequential time points throughout the course of radiation therapy to a dose of 81 Gy in 1.8-Gy fractions. Results: There was a significant decrease in mean prostate volume of 10.9% from the first to the final day of radiation therapy. The volume loss did not occur monotonically but increased in most patients (75%) during the first several weeks to a median maximum on Day 7. The volume increased by a mean of 6.1% before decreasing by a mean maximum difference of 18.4% to nadir (p < 0.001 for both increase and decrease). Glandular shrinkage was asymmetric, with the apex to right base dimension varying more than twice that of the lateral dimension. For all dimensions, the mean change was <0.5 cm. Conclusion: Real-time transponder positions indicated a volume increase during the initial days of radiation therapy and then significant and asymmetric shrinkage by the final day. Understanding and tracking volume fluctuations of the prostate during radiation therapy can help real-time imaging technology perform to its fullest potential.

  3. Metabolic engineering of the purine biosynthetic pathway in Corynebacterium glutamicum results in increased intracellular pool sizes of IMP and hypoxanthine

    PubMed Central

    2012-01-01

    Background Purine nucleotides exhibit various functions in cellular metabolism. Besides serving as building blocks for nucleic acid synthesis, they participate in signaling pathways and energy metabolism. Further, IMP and GMP represent industrially relevant biotechnological products used as flavor enhancing additives in food industry. Therefore, this work aimed towards the accumulation of IMP applying targeted genetic engineering of Corynebacterium glutamicum. Results Blocking of the degrading reactions towards AMP and GMP lead to a 45-fold increased intracellular IMP pool of 22 μmol gCDW-1. Deletion of the pgi gene encoding glucose 6-phosphate isomerase in combination with the deactivated AMP and GMP generating reactions, however, resulted in significantly decreased IMP pools (13 μmol gCDW-1). Targeted metabolite profiling of the purine biosynthetic pathway further revealed a metabolite shift towards the formation of the corresponding nucleobase hypoxanthine (102 μmol gCDW-1) derived from IMP degradation. Conclusions The purine biosynthetic pathway is strongly interconnected with various parts of the central metabolism and therefore tightly controlled. However, deleting degrading reactions from IMP to AMP and GMP significantly increased intracellular IMP levels. Due to the complexity of this pathway further degradation from IMP to the corresponding nucleobase drastically increased suggesting additional targets for future strain optimization. PMID:23092390

  4. Quantification of noise sources for amperometric measurement of quantal exocytosis using microelectrodes

    PubMed Central

    Yao, Jia

    2016-01-01

    Electrochemical microelectrodes are commonly used to record amperometric spikes of current that result from oxidation of transmitter released from individual vesicles during exocytosis. Whereas the exquisite sensitivity of these measurements is well appreciated, a better understanding of the noise sources that limit the resolution of the technique is needed to guide the design of next-generation devices. We measured the current power spectral density (SI) of electrochemical microelectrodes to understand the physical basis of dominant noise sources and to determine how noise varies with the electrode material and geometry. We find that the current noise is thermal in origin in that SI is proportional to the real part of the admittance of the electrode. The admittance of microelectrodes is well described by a constant phase element model such that both the real and imaginary admittance increase with frequency raised to a power of 0.84 – 0.96. Our results demonstrate that the current standard deviation is proportional to the square root of the area of the working electrode, increases ~linearly with the bandwidth of the recording, and varies with the choice of the electrode material with Au ≈ carbon fiber > nitrogen-doped diamond-like carbon > indium-tin-oxide. Contact between a cell and a microelectrode does not appreciably increase noise. Surface-patterned microchip electrodes can have a noise performance that is superior to that of carbon-fiber microelectrodes of the same area. PMID:22540116

  5. Scaling-down the size and increasing the throughput of glycosyltransferase assays: Activity changes upon stem-cell differentiation

    PubMed Central

    Patil, Shilpa A.; Chandrasekaran, E. V.; Matta, Khushi L.; Parikh, Abhirath; Tzanakakis, Emmanuel S.; Neelamegham, Sriram

    2012-01-01

    Glycosyltransferases (GlycoTs) catalyze the transfer of monosaccharides from nucleotide-sugars to carbohydrate, lipid and protein based acceptors. We examined strategies to scale-down and increase the throughput of glycoT enzymatic assays since traditional methods require large reaction volumes and complex chromatography. Approaches tested utilized: i) Microarray pin-printing. This method was appropriate when glycoT activity was high; ii) Microwells and microcentrifuge tubes. This was suitable for studies with cell lysates when enzyme activity was moderate; iii) C18 pipette tips and solvent-extraction. This enriched reaction product when the extent of reaction was low. In all cases, reverse phase-thin layer chromatography (RP-TLC) coupled with phosphorimaging quantified reaction rate. Studies with mouse embryonic stem cells (mESCs) demonstrate an increase in overall β(1,3)galactosyltransferase and α(2,3)sialyltransferase activity, and a decrease in α(1,3)fucosyltransferases when these cells differentiation towards cardiomyocytes. Enzymatic and lectin binding data suggest a transition from LeX type structures in mESCs to sialylated Galβ1,3GalNAc type glycans upon differentiation, with more prominent changes in enzyme activity occurring at later stages when embryoid bodies differentiated to cardiomyocytes. Overall, simple, rapid, quantitative and scalable glycoT activity analysis methods are presented. These utilize a range of natural and synthetic acceptors for the analysis of complex biological specimen that have limited availability. PMID:22449497

  6. Promotion of cooperation due to diversity of players in the spatial public goods game with increasing neighborhood size

    NASA Astrophysics Data System (ADS)

    Zhu, Cheng-jie; Sun, Shi-wen; Wang, Li; Ding, Shuai; Wang, Juan; Xia, Cheng-yi

    2014-07-01

    It is well-known that individual diversity is a typical feature within the collective population. To model this kind of characteristics, we propose an evolutionary model of public goods game with two types of players (named as A and B), where players are located on the sites of a square lattice satisfying the periodic boundary conditions. The evolution of the strategy distribution is governed by iterated strategy adoption from a randomly selected neighbor with a probability, which not only depends on the payoff difference between players, but also on the type of the neighbor. For B-type agents, we pose a pre-factor (0increased from 4 to 24. Within a range of the portion of A-type influential players, the inhomogeneous teaching activity in strategy transfer yields a relevant increase (dependent on w) in the density of cooperators characterizing the promotion of cooperation. Current findings are of utmost importance for us to understand the evolution of cooperation under many real-world circumstances, such as the natural, biological, economic and even social systems.

  7. Overexpression of the Arabidopsis anaphase promoting complex subunit CDC27a increases growth rate and organ size.

    PubMed

    Rojas, Cristian Antonio; Eloy, Nubia Barbosa; Lima, Marcelo de Freitas; Rodrigues, Roberta Lopes; Franco, Luciana Ozório; Himanen, Kristiina; Beemster, Gerrit T S; Hemerly, Adriana Silva; Ferreira, Paulo Cavalcanti Gomes

    2009-10-01

    The Anaphase Promoting Complex (APC) controls CDK activity by targeting the ubiquitin-dependent proteolysis of S-phase and mitosis-promoting cyclins. Here, we report that the ectopic expression of the Arabidopsis CDC27a, an APC subunit, accelerates plant growth and results in plants with increased biomass production. CDC27a overexpression was associated to apical meristem restructuration, protoplasts with higher (3)H-thimidine incorporation and altered cell-cycle marker expression. Total protein extracts immunoprecipitated with a CDC27a antibody showed ubiquitin ligase activity, indicating that the Arabidopsis CDC27a gets incorporated into APC complexes. These results indicate a role of AtCDC27a in regulation of plant growth and raise the possibility that the activity of the APC and the rates of plant cell division could be regulated by the concentration of the CDC27a subunit. PMID:19629716

  8. Prenatal Exposure to Autism-Specific Maternal Autoantibodies Alters Proliferation of Cortical Neural Precursor Cells, Enlarges Brain, and Increases Neuronal Size in Adult Animals.

    PubMed

    Martínez-Cerdeño, Verónica; Camacho, Jasmin; Fox, Elizabeth; Miller, Elaine; Ariza, Jeanelle; Kienzle, Devon; Plank, Kaela; Noctor, Stephen C; Van de Water, Judy

    2016-01-01

    Autism spectrum disorders (ASDs) affect up to 1 in 68 children. Autism-specific autoantibodies directed against fetal brain proteins have been found exclusively in a subpopulation of mothers whose children were diagnosed with ASD or maternal autoantibody-related autism. We tested the impact of autoantibodies on brain development in mice by transferring human antigen-specific IgG directly into the cerebral ventricles of embryonic mice during cortical neurogenesis. We show that autoantibodies recognize radial glial cells during development. We also show that prenatal exposure to autism-specific maternal autoantibodies increased stem cell proliferation in the subventricular zone (SVZ) of the embryonic neocortex, increased adult brain size and weight, and increased the size of adult cortical neurons. We propose that prenatal exposure to autism-specific maternal autoantibodies directly affects radial glial cell development and presents a viable pathologic mechanism for the maternal autoantibody-related prenatal ASD risk factor. PMID:25535268

  9. Class Size.

    ERIC Educational Resources Information Center

    Johnston, Holly R.

    Exploring the class-size issue, this paper focuses on the primary grades and asks questions such as "does a reduction in class size promote an increase in academic achievement?" and "how substantial does the reduction in numbers have to be in order for a significant increase to occur?" The paper surveys debates on class size and the social factors…

  10. Subtle increases in heart size persist into adulthood in growth restricted babies: the Cardiovascular Risk in Young Finns Study

    PubMed Central

    Arnott, Clare; Skilton, Michael R; Ruohonen, Saku; Juonala, Markus; Viikari, Jorma S A; Kähönen, Mika; Lehtimäki, Terho; Laitinen, Tomi; Celermajer, David S; Raitakari, Olli T

    2015-01-01

    Background and objectives Impaired fetal growth is associated with increased cardiovascular morbidity and mortality in adulthood. We sought to determine whether adults born with intrauterine growth restriction have primary maladaptive changes in cardiac structure. Methods Study participants were adults (34–49 years) who attended the 31-year follow-up of the Cardiovascular Risk in Young Finns Study (longitudinal cohort). Transthoracic echocardiograms and demographic and cardiovascular risk surveys were completed for 157 adults born small for gestational age (SGA, birth weight <10th population centile) and 627 born average for gestational age (average for gestational age (AGA), birth weight 50th–90th population centile). Results Those born growth restricted had subtly enlarged hearts with indexed left ventricular (LV) end-systolic and end-diastolic diameters slightly greater in the SGA individuals than the AGA group (LVESD 18.7 mm/m2 SGA vs 18.1 mm/m2 AGA, p<0.01; LVEDD 27.5 mm/m2 SGA vs 26.6 mm/m2 AGA, p<0.01); LV base-to-apex length (47.4 mm/m2 SGA vs 46.0 mm/m2 AGA, p<0.01); LV basal diameter (26.4 mm/m2 SGA vs 25.7 mm/m2 AGA, p<0.01); and right ventricular base-to-apex length (40.1 mm/m2 SGA vs 39.2 mm/m2 AGA, p=0.02). LV stroke volume was greater in those born AGA (74.5 mL SGA vs 78.8 mL AGA, p<0.01), with no significant difference in cardiac output (5 L/min SGA vs 5.2 L/min AGA, p=0.06), heart rate, diastolic indices or sphericity index. Conclusions Adults born SGA have some statistically significant but subtle changes in cardiac structure and function, which are less marked than have been described in childhood, and are unlikely to play a pathogenic role in their elevated cardiovascular risk. PMID:26339495

  11. The quantal source of area supralinearity of flash responses in Limulus photoreceptors

    PubMed Central

    1988-01-01

    The time integrals of the responses of dark-adapted Limulus ventral photoreceptors to flashes exhibit a supralinear dependence on intensity at intermediate intensities. By decomposing the responses into their elementary single-photon components ("bumps"), we are able to calculate the overall quantum efficiency and to display the time courses of the bump amplitude and rate of appearance. Since the time course of the flash response is not slow compared with that of the bump, it was necessary, in order to carry out the decomposition, to develop a new technique for noise analysis of dynamic signals. This new technique should have wide applications. Our main finding is that the supralinearity of the flash responses corresponds to an increase in bump amplitude, with little change in bump duration or quantum efficiency. The time courses of the bump rate and of the change in bump amplitude are peaked and have widths similar to that of the response itself. The peaks of the time courses of the bump rate and amplitude displayed against the starting times of the bumps do not coincide and occur approximately 80 and approximately 40 ms, respectively, before the peak of the response. The time from the start of a bump to its centroid is approximately 70 ms, which means that the time at which the bump centroid reaches its maximum follows the response peak by 30 ms. These results impose constraints on possible mechanisms for the amplitude enhancement. PMID:3418317

  12. Intestinal and peritoneal mast cells differ in kinetics of quantal release.

    PubMed

    Balseiro-Gomez, Santiago; Ramirez-Ponce, M Pilar; Acosta, Jorge; Ales, Eva; Flores, Juan A

    2016-01-15

    5-hydroxytriptamine (5-HT, serotonin) storage and release in mast cell (MC) secretory granules (SG) are dependent on serglycin proteoglycans (PG). This notion is based on the studies of MC of the connective tissue subtype that predominantly contain PG of the heparin type, whereas intestinal mucosal MC, which contain predominantly chondroitin sulfate, have been poorly explored. In the present study, we addressed the possibility that PG contents may differently affect the storage and release of preformed mediators in these two MC subclasses and explain in part their different functional properties. Rat peritoneal (PMC) and intestinal mast cells (IMC) were isolated and purified using a percoll gradient, and the efflux of 5-HT from each SG was measured by amperometric detection. IMC exhibited a ∼34% reduction in the release of 5-HT compared with PMC because of a lower number of exocytotic events, rather than a lower secretion per single exocytotic event. Amperometric spikes from IMC exhibited a slower decay phase and increased half-width but a similar ascending phase and foot parameters, indicating that the fusion pore kinetics are comparable in both MC subclasses. We conclude that both PG subtypes are equally efficient systems, directly involved in serotonin accumulation, and play a crucial role in regulating the kinetics of exocytosis from SG, providing specific secretory properties for the two cellular subtypes. PMID:26692491

  13. Random Photon Absorption Model Elucidates How Early Gain Control in Fly Photoreceptors Arises from Quantal Sampling

    PubMed Central

    Song, Zhuoyi; Zhou, Yu; Juusola, Mikko

    2016-01-01

    Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantum-gain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantum-gain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multi-photon-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to light-adaptation is marginal (≤ 1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light. PMID:27445779

  14. Does increasing the size of bi-weekly samples of records influence results when using the Global Trigger Tool? An observational study of retrospective record reviews of two different sample sizes

    PubMed Central

    Mevik, Kjersti; Griffin, Frances A; Hansen, Tonje E; Deilkås, Ellen T; Vonen, Barthold

    2016-01-01

    Objectives To investigate the impact of increasing sample of records reviewed bi-weekly with the Global Trigger Tool method to identify adverse events in hospitalised patients. Design Retrospective observational study. Setting A Norwegian 524-bed general hospital trust. Participants 1920 medical records selected from 1 January to 31 December 2010. Primary outcomes Rate, type and severity of adverse events identified in two different samples sizes of records selected as 10 and 70 records, bi-weekly. Results In the large sample, 1.45 (95% CI 1.07 to 1.97) times more adverse events per 1000 patient days (39.3 adverse events/1000 patient days) were identified than in the small sample (27.2 adverse events/1000 patient days). Hospital-acquired infections were the most common category of adverse events in both the samples, and the distributions of the other categories of adverse events did not differ significantly between the samples. The distribution of severity level of adverse events did not differ between the samples. Conclusions The findings suggest that while the distribution of categories and severity are not dependent on the sample size, the rate of adverse events is. Further studies are needed to conclude if the optimal sample size may need to be adjusted based on the hospital size in order to detect a more accurate rate of adverse events. PMID:27113238

  15. Increased sedimentation rates and grain sizes 2-4 Myr ago due to the influence of climate change on erosion rates.

    PubMed

    Peizhen, Z; Molnar, P; Downs, W R

    2001-04-19

    Around the globe, and in a variety of settings including active and inactive mountain belts, increases in sedimentation rates as well as in grain sizes of sediments were recorded at approximately 2-4 Myr ago, implying increased erosion rates. A change in climate represents the only process that is globally synchronous and can potentially account for the widespread increase in erosion and sedimentation, but no single process-like a lowering of sea levels or expanded glaciation-can explain increases in sedimentation in all environments, encompassing continental margins and interiors, and tropical as well as higher latitudes. We suggest that climate affected erosion mainly by the transition from a period of climate stability, in which landscapes had attained equilibrium configurations, to a time of frequent and abrupt changes in temperature, precipitation and vegetation, which prevented fluvial and glacial systems from establishing equilibrium states. PMID:11309607

  16. Enhanced Stomatal Conductance by a Spontaneous Arabidopsis Tetraploid, Me-0, Results from Increased Stomatal Size and Greater Stomatal Aperture1[OPEN

    PubMed Central

    Monda, Keina; Araki, Hiromitsu; Kuhara, Satoru; Ishigaki, Genki; Akashi, Ryo; Negi, Juntaro; Kojima, Mikiko; Sakakibara, Hitoshi; Takahashi, Sho; Hashimoto-Sugimoto, Mimi; Goto, Nobuharu; Iba, Koh

    2016-01-01

    The rate of gas exchange in plants is regulated mainly by stomatal size and density. Generally, higher densities of smaller stomata are advantageous for gas exchange; however, it is unclear what the effect of an extraordinary change in stomatal size might have on a plant’s gas-exchange capacity. We investigated the stomatal responses to CO2 concentration changes among 374 Arabidopsis (Arabidopsis thaliana) ecotypes and discovered that Mechtshausen (Me-0), a natural tetraploid ecotype, has significantly larger stomata and can achieve a high stomatal conductance. We surmised that the cause of the increased stomatal conductance is tetraploidization; however, the stomatal conductance of another tetraploid accession, tetraploid Columbia (Col), was not as high as that in Me-0. One difference between these two accessions was the size of their stomatal apertures. Analyses of abscisic acid sensitivity, ion balance, and gene expression profiles suggested that physiological or genetic factors restrict the stomatal opening in tetraploid Col but not in Me-0. Our results show that Me-0 overcomes the handicap of stomatal opening that is typical for tetraploids and achieves higher stomatal conductance compared with the closely related tetraploid Col on account of larger stomatal apertures. This study provides evidence for whether larger stomatal size in tetraploids of higher plants can improve stomatal conductance. PMID:26754665

  17. The elusive quantal individual

    NASA Astrophysics Data System (ADS)

    Groenewold, H. J.

    1985-10-01

    In the formal hedgehog representation of quantum mechanics [5] (ambiguous) weights are derived for hedgehogs with a finite number of questions and answers, in particular applied to spin {1}/{2} and to correlated spin {1}/{2} pairs. Unavoidable negative weights are a clear signal for conceptual difficulties in quantum mechanical interpretation. If these weights had been presupposed to be non-negative, they could have led to Bell-like inequalities inconsistent with quantum mechanics. This is what has happened already in various special models. Owing to the indefinite weights, the hedgehog hypothesis of one-to-one mapping between individual physical samples and individual fictitious hedgehogs cannot be maintained. If no physical interpretation is conceived for the negative weights, the only way to avoid unsolved conceptual difficulties appears to resign (even in the hedgehog representation) to the skeptical ensemble interpretation [1], without theorizing about individual physical samples at all.

  18. Increased size of solid organs in patients with Chuvash polycythemia and in mice with altered expression of HIF-1α and HIF-2α

    PubMed Central

    Yoon, Donghoon; Okhotin, David V.; Kim, Bumjun; Okhotina, Yulia; Okhotin, Daniel J.; Miasnikova, Galina Y.; Sergueeva, Adelina I.; Polyakova, Lydia A.; Maslow, Alexei; Lee, Yonggu; Semenza, Gregg L.; Prchal, Josef T.

    2010-01-01

    Chuvash polycythemia, the first hereditary disease associated with dysregulated oxygen-sensing to be recognized, is characterized by a homozygous germ-line loss-of-function mutation of the VHL gene (VHLR200W) resulting in elevated hypoxia inducible factor (HIF)-1α and HIF-2α levels, increased red cell mass and propensity to thrombosis. Organ volume is determined by the size and number of cells, and the underlying molecular control mechanisms are not fully elucidated. Work from several groups has demonstrated that the proliferation of cells is regulated in opposite directions by HIF-1α and HIF-2α. HIF-1α inhibits cell proliferation by displacing MYC from the promoter of the gene encoding the cyclin-dependent kinase inhibitor, p21Cip1, thereby inducing its expression. In contrast, HIF-2α promotes MYC activity and cell proliferation. Here we report that the volumes of liver, spleen, and kidneys relative to body mass were larger in 30 individuals with Chuvash polycythemia than in 30 matched Chuvash controls. In Hif1a+/− mice, which are heterozygous for a null (knockout) allele at the locus encoding HIF-1α, hepatic HIF-2α mRNA was increased (2-fold) and the mass of the liver was increased, compared with wild-type littermates, without significant difference in cell volume. Hepatic p21Cip1 mRNA levels were 9.5-fold lower in Hif1a+/− mice compared with wild-type littermates. These data suggest that, in addition to increased red cell mass, the sizes of liver, spleen, and kidneys are increased in Chuvash polycythemia. At least in the liver, this phenotype may result from increased HIF-2α and decreased p21Cip1 levels leading to increased hepatocyte proliferation. PMID:20140661

  19. Increased size of solid organs in patients with Chuvash polycythemia and in mice with altered expression of HIF-1alpha and HIF-2alpha.

    PubMed

    Yoon, Donghoon; Okhotin, David V; Kim, Bumjun; Okhotina, Yulia; Okhotin, Daniel J; Miasnikova, Galina Y; Sergueeva, Adelina I; Polyakova, Lydia A; Maslow, Alexei; Lee, Yonggu; Semenza, Gregg L; Prchal, Josef T; Gordeuk, Victor R

    2010-05-01

    Chuvash polycythemia, the first hereditary disease associated with dysregulated oxygen-sensing to be recognized, is characterized by a homozygous germ-line loss-of-function mutation of the VHL gene (VHL(R200W)) resulting in elevated hypoxia inducible factor (HIF)-1alpha and HIF-2alpha levels, increased red cell mass and propensity to thrombosis. Organ volume is determined by the size and number of cells, and the underlying molecular control mechanisms are not fully elucidated. Work from several groups has demonstrated that the proliferation of cells is regulated in opposite directions by HIF-1alpha and HIF-2alpha. HIF-1alpha inhibits cell proliferation by displacing MYC from the promoter of the gene encoding the cyclin-dependent kinase inhibitor, p21(Cip1), thereby inducing its expression. In contrast, HIF-2alpha promotes MYC activity and cell proliferation. Here we report that the volumes of liver, spleen, and kidneys relative to body mass were larger in 30 individuals with Chuvash polycythemia than in 30 matched Chuvash controls. In Hif1a(+/-) mice, which are heterozygous for a null (knockout) allele at the locus encoding HIF-1alpha, hepatic HIF-2alpha mRNA was increased (2-fold) and the mass of the liver was increased, compared with wild-type littermates, without significant difference in cell volume. Hepatic p21(Cip1) mRNA levels were 9.5-fold lower in Hif1a(+/-) mice compared with wild-type littermates. These data suggest that, in addition to increased red cell mass, the sizes of liver, spleen, and kidneys are increased in Chuvash polycythemia. At least in the liver, this phenotype may result from increased HIF-2alpha and decreased p21(Cip1) levels leading to increased hepatocyte proliferation. PMID:20140661

  20. Low dose of IGF-I increases cell size of skeletal muscle satellite cells via Akt/S6K signaling pathway.

    PubMed

    Gao, Chun-qi; Zhi, Rui; Yang, Zhou; Li, Hai-chang; Yan, Hui-chao; Wang, Xiu-qi

    2015-11-01

    The objective of this study was to investigate the effect of insulin growth factor-I (IGF-I) on the size of pig skeletal muscle satellite cells (SCs). Using microarray, real-time RT-PCR, radioimmunoassay analysis and western blot, we first showed that supplementation of low-dose of IGF-I in culture medium resulted in enlarged cell size of Lantang SCs, only Akt and S6K were up-regulated at both the mRNA and protein levels among almost all of the mTOR pathway key genes, but had no effect on cell number. To elucidate the signaling mechanisms responsible for regulating cell size under low-dose of IGF-I treatment, we blocked Akt and S6K activity with the specific inhibitors MK2206 and PF4708671, respectively. Both inhibitors caused a decrease in cell size. In addition, MK2206 lowered the protein level of p-Akt (Ser473), p-S6K (Thr389), and p-rpS6 (Ser235/236), whereas PF4708671 lowered the protein level of p-S6K (Thr389) and p-rpS6 (Ser235/236). However, low dose of IGF-I didn't affect the protein level of p-mTOR (Ser2448) and p-mTOR (Ser2481). When both inhibitors were applied simultaneously, the effect was the same as that of the Akt inhibition alone. Taken together, we report for the first time that low-dose of IGF-I treatment increases cell size via Akt/S6K signaling pathway. PMID:25923195

  1. [Intubation using the Pentax-AWS Airwayscope with an infant-size Intlock in a patient with increased intracranial pressure due to acute hydrocephalus].

    PubMed

    Matsunami, Sayuri; Komasawa, Nobuyasu; Nakao, Kenta; Nakano, Shoko; Tatsumi, Shinichi; Minami, Toshiaki

    2014-04-01

    We report our experience with the Pentax-AWS Airwayscope with an infant-size Intlock (AWS-I) in a patient with increased intracranial pressure due to acute hydrocephalus. A 12-month-old female infant with increased intracranial pressure due to acute hydrocephalus was scheduled to undergo emergent ventriculoperitoneal shunting under general anesthesia. She had a clonic convulsion and was sedated with midazolam. As her head was enlarged, head-tilting was difficult. Tracheal intubation while preventing an intracranial pressure increase was needed. After induction of general anesthesia with thiamylal and fentanyl the AWS-I was inserted to obtain a laryngoscopic view without excessive force. Under AWS observation, tracheal intubation was uneventful, and no vital sign change was observed. PMID:24783606

  2. Angiopoietin-2-induced blood-brain barrier compromise and increased stroke size are rescued by VE-PTP-dependent restoration of Tie2 signaling.

    PubMed

    Gurnik, Stefanie; Devraj, Kavi; Macas, Jadranka; Yamaji, Maiko; Starke, Julia; Scholz, Alexander; Sommer, Kathleen; Di Tacchio, Mariangela; Vutukuri, Rajkumar; Beck, Heike; Mittelbronn, Michel; Foerch, Christian; Pfeilschifter, Waltraud; Liebner, Stefan; Peters, Kevin G; Plate, Karl H; Reiss, Yvonne

    2016-05-01

    The homeostasis of the central nervous system is maintained by the blood-brain barrier (BBB). Angiopoietins (Ang-1/Ang-2) act as antagonizing molecules to regulate angiogenesis, vascular stability, vascular permeability and lymphatic integrity. However, the precise role of angiopoietin/Tie2 signaling at the BBB remains unclear. We investigated the influence of Ang-2 on BBB permeability in wild-type and gain-of-function (GOF) mice and demonstrated an increase in permeability by Ang-2, both in vitro and in vivo. Expression analysis of brain endothelial cells from Ang-2 GOF mice showed a downregulation of tight/adherens junction molecules and increased caveolin-1, a vesicular permeability-related molecule. Immunohistochemistry revealed reduced pericyte coverage in Ang-2 GOF mice that was supported by electron microscopy analyses, which demonstrated defective intra-endothelial junctions with increased vesicles and decreased/disrupted glycocalyx. These results demonstrate that Ang-2 mediates permeability via paracellular and transcellular routes. In patients suffering from stroke, a cerebrovascular disorder associated with BBB disruption, Ang-2 levels were upregulated. In mice, Ang-2 GOF resulted in increased infarct sizes and vessel permeability upon experimental stroke, implicating a role of Ang-2 in stroke pathophysiology. Increased permeability and stroke size were rescued by activation of Tie2 signaling using a vascular endothelial protein tyrosine phosphatase inhibitor and were independent of VE-cadherin phosphorylation. We thus identified Ang-2 as an endothelial cell-derived regulator of BBB permeability. We postulate that novel therapeutics targeting Tie2 signaling could be of potential use for opening the BBB for increased CNS drug delivery or tighten it in neurological disorders associated with cerebrovascular leakage and brain edema. PMID:26932603

  3. An Increase in Forearm Cortical Bone Size After Menopause May Influence the Estimated Bone Mineral Loss--A 28-Year Prospective Observational Study.

    PubMed

    Karlsson, Magnus K; Ahlborg, Henrik G; Svejme, Ola; Nilsson, Jan-Åke; Rosengren, Björn E

    2016-01-01

    Areal bone mineral density (aBMD) is the most common estimate of bone mass, incorporated in the World Health Organization definition of osteoporosis. However, aBMD depends on not only the amount of mineral but also the bone size. The estimated postmenopausal decline in aBMD could because of this be influenced by changes in bone size.We measured bone mineral content (BMC; mg), aBMD (mg/cm2), and bone width (mm) by single-photon absorptiometry at the cortical site of the forearm in a population-based sample of 105 Caucasian women. We conducted 12 measurements during a 28-yr period from mean 5 yr (range: 2-9) before menopause to mean 24 yr (range: 18-28) after menopause. We calculated individual slopes for changes in the periods before menopause, 0-<8, 8-<16, and 16-28 yr after menopause. Data are presented as means with 95% confidence intervals. The annual BMC changes in the 4 periods were -1.4% (-0.1, -2.6), -1.1% (-0.9, -1.4), -1.2% (-0.9, -1.6), and -1.1% (-0.8, -1.4) and the annual increase in bone width 0.4% (-1.2, 1.9), 0.7% (0.5, 0.9), 0.1% (-0.2, 0.4), and 0.1% (-0.2, 0.4). BMC loss was similar in all periods, whereas the increase in bone width was higher in the first postmenopausal period than in the second (p=0.003) and the third (p=0.01) postmenopausal periods. Menopause is followed by a transient increase in forearm bone size that will influence the by aBMD estimated cortical loss in bone minerals. PMID:25708121

  4. Elevated Body Position Early after Delivery Increased Airway Size during Wakefulness, and Decreased Apnea Hypopnea Index in a Woman with Pregnancy Related Sleep Apnea

    PubMed Central

    Jung, Stefanie; Zaremba, Sebastian; Heisig, Anne; Eikermann, Matthias

    2014-01-01

    We report a patient with pregnancy related obstructive sleep apnea ([OSA]; apnea hypopnea index [AHI] 18/h) early after delivery, with improvement of AHI by 87% following 45-degree elevation in body position compared with the non-elevated position. Improvement associated with this position may be explained, at least in part, by an increased upper airway diameter (as measured during wakefulness). Sleep apnea in this patient resolved at 9 months postpartum. This observation suggests that 45-degree elevated body position may be an effective treatment of pregnancy related OSA during the postpartum period. Citation: Jung S, Zaremba S, Heisig A, Eikermann M. Elevated body position early after delivery increased airway size during wakefulness, and decreased apnea hypopnea index in a woman with pregnancy related sleep apnea. J Clin Sleep Med 2014;10(7):815-817. PMID:25024663

  5. Increasing sensitivity and decreasing spot size using an inexpensive, removable hydrophobic coating for matrix-assisted laser desorption/ionisation plates.

    PubMed

    Owen, Stacey J; Meier, Felix S; Brombacher, Stephan; Volmer, Dietrich A

    2003-01-01

    Spot size reduction and increased detection sensitivity in matrix-assisted laser desorption/ionisation (MALDI) of small molecules are accomplished by using an inexpensive and removable hydrophobic coating for MALDI targets, based on 3M Scotch Gard surface treatment. Several variations in sample preparation were explored, such as surface coating technique, identity of the matrix, solvent composition, and the type of metal support plate used. These were investigated on both uncoated and coated surfaces and their impact on spot size, crystal coverage, and sensitivity is presented here. Additionally, crystallisation behaviour obtained on coated plates is compared with that on uncoated plates using scanning electron microscope analysis. To demonstrate the potential of the new coating technique, erythromycin A and valinomycin are studied to determine the increase in detection sensitivity of coated plates in comparison to uncoated plates, and to reveal the suitability of the plates for application in combined high-performance liquid chromatography/MALDI (HPLC/MALDI), where widely varying solvent compositions and droplet volumes are observed. It is shown that enhancements in detection sensitivities correlate very well with the achieved spot size reduction. The versatility of the coated plates is also exhibited by the ease of removing the surface layer, after which the plates can be rigorously cleaned without worry about damaging the hydrophobic surface, followed by a quick reapplication of new hydrophobic coating material. This makes the non-polar coating superior to more expensive commercial hydrophobic-coated targets, which are much more delicate to clean. Furthermore, cleaning and reapplication eliminate potential carry-over effects and the easy application procedure also makes the fabrication of inexpensive, disposable MALDI targets readily possible. PMID:14587091

  6. Hydrogen Photoevolution Indicates an Increase in the Antenna Size of Photosystem I in Chlamydobotrys stellata during Transition from Autotrophic to Photoheterotrophic Nutrition 1

    PubMed Central

    Boichenko, Vladimir A.; Wiessner, Wolfgang; Klimov, Vyacheslav V.; Mende, Dierk; Demeter, Sándor

    1992-01-01

    The changes in the light-harvesting antenna size of photosystem I were investigated in the green alga Chlamydobotrys stellata during transition from autotrophic to photoheterotrophic nutrition by measuring the light-saturation behavior of hydrogen evolution following single turnover flashes. It was found that during autotrophic-to-photoheterotrophic transition the antenna size of photosystem I increased from 180 to 250 chlorophyll. The chlorophyll (a + b)/P700 ratio decreased from 800 to 550. The electron transport of photosystem I measured from reduced 2,6-dichloro-phenolindophenol to methylviologen was accelerated 1.4 times. In the 77K fluorescence spectra, the photosystem II fluorescence yield was considerably lowered relative to the photosystem I fluorescence yield. It is suggested that the increased light-harvesting capacity and redistribution of absorbed excitation energy in favor of photosystem I is a response of photoheterotrophic algae to meet the ATP demand for acetate metabolism by efficient photosystem I cyclic electron transport when the noncyclic photophosphorylation is inhibited by CO2 deficiency. PMID:16652992

  7. Melatonin promotes the cumulus-oocyte complexes quality of vitrified-thawed murine ovaries; with increased mean number of follicles survival and ovary size following heterotopic transplantation.

    PubMed

    Hemadi, Masoud; Abolhassani, Farid; Akbari, Mohammad; Sobhani, Aligholi; Pasbakhsh, Parichehr; Ahrlund-Richter, Lars; Modaresi, Mohammad H; Salehnia, Mojdeh

    2009-09-15

    We have tested the protective effect of melatonin on neonate murine ovarian tissue after vitrification, thawing and heterotopic transplantation into ovariectomized recipient mice. Vitrified ovaries from neonate (CBA x C57Bl/6) F1 hybrid mice were thawed under standard condition with or without the addition of 100 microM melatonin. Following transplantation, melatonin (20 mg/kg/day) or saline solution (physiological saline) was injected i.p. to the treated and non-treated groups for 48 h respectively. Follicle survival and development, together with ovary size followed. Also, vaginal cytology was carried out for monitoring restored puberty. Histological and immunohistochemical studies showed that melatonin could promote the quality of the cumulus-oocyte complexes with uniform distribution of granulosa and stromal cells in the ovarian grafts. Furthermore, the mean follicles survival was improved and the ovary size increased (P< or = 0.001). The overall mean number of follicles entering the next maturation stage dramatically increased. However, the revascularization and restoration of puberty of ovarian grafts were similar between melatonin-treated and control groups. In conclusion, melatonin as a protection from ischemic injury and a reduce oxidative stress, was shown beneficial during the early days of transplantation. PMID:19622351

  8. The Relationship of the Increase in the 'Time of the Earth Day,' from 18 Hours to 24 Hours, to the Increase in the Size of the Earth, Using the Laws of the Conservation of Momentum

    NASA Astrophysics Data System (ADS)

    Cimorelli, S. A.; Samuels, C.

    2010-12-01

    There are three articles, by others, which discuss the increase in the Earth's day, from 18 hours to 24 hours, over a period of time of about a billion years. One article refers to Striations in the Substructure of Coral, C.T. Scrutton, et al, 1965. Another article refers to the Laws of the Conservation of Momentum, as related to the relationship of the Earth and the Moon, the lunar tides, the reduction of the Earth year from 481 days to our present 365.25 days, and an increase in the lunar orbit time from 20 days to 28 days. The third article is based on the dates of tidal sediment deposits, tidalites, C. P. Sonett, et al, in the late 1980's. In this paper, we explain how the Earth's Day could have increased from 18 hours to 24 hours, as related to the Laws of Conservation of Momentum (L). Wherein we use the simple formulation from the Law of the Conservation of Angular Momentum, L=Iω, in which I=Moment of Inertia and ω=Angular Velocity; for which we assume the earth to be a perfect sphere, for which I=0.4MR2, where M and R are the Mass and radius of the earth, respectively. We evaluate the radius of the earth over a time period of several billion years, during which time the earth's angular momentum, L=Iω, is conserved. In this formulation, we show a growth in the size of the earth; and present a curve, using just three points in time, which indicates that the rate of growth is increasing over time. The first point is from about 4.5 billion years ago, the second point is from about 1 billion years ago, and the third point represents present day, with an average growth of about 1mm per year. Although evidence has been presented, by others, showing circumferential growth at the Red Sea and in the Atlantic Ocean, at about 1.5cm per year, total. However, no proof of reduction in the size of the Earth has been shown to occur in the Pacific, or anywhere else, including in references to subduction. Some might say that the subduction is occurring at the rim of the

  9. Deletion of Mbtps1 (Pcsk8, S1p, Ski-1) Gene in Osteocytes Stimulates Soleus Muscle Regeneration and Increased Size and Contractile Force with Age.

    PubMed

    Gorski, Jeff P; Huffman, Nichole T; Vallejo, Julian; Brotto, Leticia; Chittur, Sridar V; Breggia, Anne; Stern, Amber; Huang, Jian; Mo, Chenglin; Seidah, Nabil G; Bonewald, Lynda; Brotto, Marco

    2016-02-26

    Conditional deletion of Mbtps1 (cKO) protease in bone osteocytes leads to an age-related increase in mass (12%) and in contractile force (30%) in adult slow twitch soleus muscles (SOL) with no effect on fast twitch extensor digitorum longus muscles. Surprisingly, bone from 10-12-month-old cKO animals was indistinguishable from controls in size, density, and morphology except for a 25% increase in stiffness. cKO SOL exhibited increased expression of Pax7, Myog, Myod1, Notch, and Myh3 and 6-fold more centralized nuclei, characteristics of postnatal regenerating muscle, but only in type I myosin heavy chain-expressing cells. Increased expression of gene pathways mediating EGF receptor signaling, circadian exercise, striated muscle contraction, and lipid and carbohydrate oxidative metabolism were also observed in cKO SOL. This muscle phenotype was not observed in 3-month-old mice. Although Mbtps1 mRNA and protein expression was reduced in cKO bone osteocytes, no differences in Mbtps1 or cre recombinase expression were observed in cKO SOL, explaining this age-related phenotype. Understanding bone-muscle cross-talk may provide a fresh and novel approach to prevention and treatment of age-related muscle loss. PMID:26719336

  10. Differences in pup birth weight, pup variability within litters, and dam weight of mice selected for alternative criteria to increase litter size.

    PubMed

    van Engelen, M A; Nielsen, M K; Ribeiro, E L

    1995-07-01

    Selection for litter size had been practiced for 21 generations and relaxed selection for 13 generations in mice. Three replicates were used with four selection criteria: index of components (ovulation rate and ova success), uterine capacity, litter size, and an unselected control. Especially with selection for litter size and the index relative to the control, number of pups born had increased, and differences also occurred in mating weight. Dams of the three replicates and their litters were used to evaluate the effects of accumulated selection on pup birth weight, variability in weight of littermates, and dam's weight at mating and after littering. Total number born, number born alive, number of males, and number of females were also recorded and studied. Mean pup birth weight did not differ among the criteria; however, variability among littermates in pup weight tended to differ among criteria of selection. Regressions for pup weight and within-litter standard deviation of pup weight on number born were small and negative but significant (P < .001). The distribution of pup weight within litter was normal for 77.2% of the litters, with no differences among the criteria. The difference between weight of male and weight of female pups was significant (P < .001); overall males were 2.5% heavier than females. There was a difference (P < .02) among criteria in mating weight and littering weight; however, the maternal weight gain between mating and littering was not different among criteria. Number born differed (P < .003) among the criteria, but there was no significant difference among criteria in numbers of males and females.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7592078

  11. Net Metering Policy Development and Distributed Solar Generation in Minnesota: Overview of Trends in Nationwide Policy Development and Implications of Increasing the Eligible System Size Cap

    SciTech Connect

    Doris, E.; Busche, S.; Hockett, S.

    2009-12-01

    The goal of the Minnesota net metering policy is to give the maximum possible encouragement to distributed generation assets, especially solar electric systems (MN 2008). However, according to a published set of best practices (NNEC 2008) that prioritize the maximum development of solar markets within states, the Minnesota policy does not incorporate many of the important best practices that may help other states transform their solar energy markets and increase the amount of grid-connected distributed solar generation assets. Reasons cited include the low system size limit of 40kW (the best practices document recommends a 2 MW limit) and a lack of language protecting generators from additional utility fees. This study was conducted to compare Minnesota's policies to national best practices. It provides an overview of the current Minnesota policy in the context of these best practices and other jurisdictions' net metering policies, as well as a qualitative assessment of the impacts of raising the system size cap within the policy based on the experiences of other states.

  12. Knockout of the abundant Trichomonas vaginalis hydrogenosomal membrane protein TvHMP23 increases hydrogenosome size but induces no compensatory up-regulation of paralogous copies.

    PubMed

    Brás, Xavier Pereira; Zimorski, Verena; Bolte, Kathrin; Maier, Uwe-G; Martin, William F; Gould, Sven B

    2013-05-01

    The Trichomonas vaginalis genome encodes up to 60000 genes, many of which stem from genome duplication events. Paralogous copies thus accompany most T. vaginalis genes, a phenomenon that limits genetic manipulation. We characterized one of the parasite's most abundant hydrogenosomal membrane proteins, TvHMP23, which is phylogenetically distinct from canonical metabolite carriers, and which localizes to the inner hydrogenosomal membrane as shown through sub-organellar fractionation and protease protection assays. Knockout of Tvhmp23 through insertion of the selectable neomycin marker led to a size increase of hydrogenosomes, the first knockout-induced phenotypes reported for Trichomonas, but no growth impairment. The transcriptional response of its four paralogous copies then analyzed revealed that they are not up-regulated, and hence do not compensate for the Tvhmp23 knockout. PMID:23499435

  13. Fusion Pore Size Limits 5-HT Release From Single Enterochromaffin Cell Vesicles.

    PubMed

    Raghupathi, Ravinarayan; Jessup, Claire F; Lumsden, Amanda L; Keating, Damien J

    2016-07-01

    Enterochromaffin cells are the major site of serotonin (5-HT) synthesis and secretion providing ∼95% of the body's total 5-HT. 5-HT can act as a neurotransmitter or hormone and has several important endocrine and paracrine roles. We have previously demonstrated that EC cells release small amounts of 5-HT per exocytosis event compared to other endocrine cells. We utilized a recently developed method to purify EC cells to demonstrate the mechanisms underlying 5-HT packaging and release. Using the fluorescent probe FFN511, we demonstrate that EC cells express VMAT and that VMAT plays a functional role in 5-HT loading into vesicles. Carbon fiber amperometry studies illustrate that the amount of 5-HT released per exocytosis event from EC cells is dependent on both VMAT and the H(+)-ATPase pump, as demonstrated with reserpine or bafilomycin, respectively. We also demonstrate that increasing the amount of 5-HT loaded into EC cell vesicles does not result in an increase in quantal release. As this indicates that fusion pore size may be a limiting factor involved, we compared pore diameter in EC and chromaffin cells by assessing the vesicle capture of different-sized fluorescent probes to measure the extent of fusion pore dilation. This identified that EC cells have a reduced fusion pore expansion that does not exceed 9 nm in diameter. These results demonstrate that the small amounts of 5-HT released per fusion event in EC cells can be explained by a smaller fusion pore that limits 5-HT release capacity from individual vesicles. PMID:26574734

  14. Increased HDL Size and Enhanced Apo A-I Catabolic Rates Are Associated With Doxorubicin-Induced Proteinuria in New Zealand White Rabbits.

    PubMed

    López-Olmos, Victoria; Carreón-Torres, Elizabeth; Luna-Luna, María; Flores-Castillo, Cristobal; Martínez-Ramírez, Miriam; Bautista-Pérez, Rocío; Franco, Martha; Sandoval-Zárate, Julio; Roldán, Francisco-Javier; Aranda-Fraustro, Alberto; Soria-Castro, Elizabeth; Muñoz-Vega, Mónica; Fragoso, José-Manuel; Vargas-Alarcón, Gilberto; Pérez-Méndez, Oscar

    2016-03-01

    The catabolism and structure of high-density lipoproteins (HDL) may be the determining factor of their atheroprotective properties. To better understand the role of the kidney in HDL catabolism, here we characterized HDL subclasses and the catabolic rates of apo A-I in a rabbit model of proteinuria. Proteinuria was induced by intravenous administration of doxorubicin in New Zealand white rabbits (n = 10). HDL size and HDL subclass lipids were assessed by electrophoresis of the isolated lipoproteins. The catabolic rate of HDL-apo A-I was evaluated by exogenous radiolabelling with iodine-131. Doxorubicin induced significant proteinuria after 4 weeks (4.47 ± 0.55 vs. 0.30 ± 0.02 g/L of protein in urine, P < 0.001) associated with increased uremia, creatininemia, and cardiotoxicity. Large HDL2b augmented significantly during proteinuria, whereas small HDL3b and HDL3c decreased compared to basal conditions. HDL2b, HDL2a, and HDL3a subclasses were enriched with triacylglycerols in proteinuric animals as determined by the triacylglycerol-to-phospholipid ratio; the cholesterol content in HDL subclasses remained unchanged. The fractional catabolic rate (FCR) of [(131)I]-apo A-I in the proteinuric rabbits was faster (FCR = 0.036 h(-1)) compared to control rabbits group (FCR = 0.026 h(-1), P < 0.05). Apo E increased and apo A-I decreased in HDL, whereas PON-1 activity increased in proteinuric rabbits. Proteinuria was associated with an increased number of large HDL2b particles and a decreased number of small HDL3b and 3c. Proteinuria was also connected to an alteration in HDL subclass lipids, apolipoprotein content of HDL, high paraoxonase-1 activity, and a rise in the fractional catabolic rate of the [(131)I]-apo A-I. PMID:26781765

  15. Maternal choline supplementation improves spatial mapping and increases basal forebrain cholinergic neuron number and size in aged Ts65Dn mice

    PubMed Central

    Ash, Jessica A.; Velazquez, Ramon; Kelley, Christy M.; Powers, Brian E.; Ginsberg, Stephen D.; Mufson, Elliott J.; Strupp, Barbara J.

    2014-01-01

    Down syndrome (DS) is marked by intellectual disability (ID) and early-onset of Alzheimer’s disease (AD) neuropathology, including basal forebrain cholinergic neuron (BFCN) degeneration. The present study tested the hypothesis that maternal choline supplementation (MCS) lessens hippocampal dysfunction and protects against BFCN degeneration in the Ts65Dn mouse model of DS and AD. During pregnancy and lactation, dams were assigned to either a choline sufficient (1.1 g/kg choline chloride) or choline supplemented (5.0 g/kg choline chloride) diet. Between 13 and 17 months of age, offspring were tested in the radial arm water maze (RAWM) to examine spatial learning and memory followed by unbiased quantitative morphometry of BFCNs. Spatial mapping was significantly impaired in unsupplemented Ts65Dn mice relative to normal disomic (2N) littermates. Additionally, a significantly lower number and density of medial septum (MS) hippocampal projection BFCNs was also found in unsupplemented Ts65Dn mice. Notably, MCS significantly improved spatial mapping and increased number, density, and size of MS BFCNs in Ts65Dn offspring. Moreover, the density and number of MS BFCNs correlated significantly with spatial memory proficiency, providing powerful support for a functional relationship between these behavioral and morphometric effects of MCS for the trisomic offspring. Thus, increasing maternal choline intake during pregnancy may represent a safe and effective treatment approach for expectant mothers carrying a DS fetus, as well as a possible means of BFCN neuroprotection during aging for the population at large. PMID:24932939

  16. Maternal choline supplementation improves spatial mapping and increases basal forebrain cholinergic neuron number and size in aged Ts65Dn mice.

    PubMed

    Ash, Jessica A; Velazquez, Ramon; Kelley, Christy M; Powers, Brian E; Ginsberg, Stephen D; Mufson, Elliott J; Strupp, Barbara J

    2014-10-01

    Down syndrome (DS) is marked by intellectual disability (ID) and early-onset of Alzheimer's disease (AD) neuropathology, including basal forebrain cholinergic neuron (BFCN) degeneration. The present study tested the hypothesis that maternal choline supplementation (MCS) improves spatial mapping and protects against BFCN degeneration in the Ts65Dn mouse model of DS and AD. During pregnancy and lactation, dams were assigned to either a choline sufficient (1.1g/kg choline chloride) or choline supplemented (5.0g/kg choline chloride) diet. Between 13 and 17months of age, offspring were tested in the radial arm water maze (RAWM) to examine spatial mapping followed by unbiased quantitative morphometry of BFCNs. Spatial mapping was significantly impaired in unsupplemented Ts65Dn mice relative to normal disomic (2N) littermates. Additionally, a significantly lower number and density of medial septum (MS) hippocampal projection BFCNs was also found in unsupplemented Ts65Dn mice. Notably, MCS significantly improved spatial mapping and increased number, density, and size of MS BFCNs in Ts65Dn offspring. Moreover, the density and number of MS BFCNs correlated significantly with spatial memory proficiency, providing support for a functional relationship between these behavioral and morphometric effects of MCS for trisomic offspring. Thus, increasing maternal choline intake during pregnancy may represent a safe and effective treatment approach for expectant mothers carrying a DS fetus, as well as a possible means of BFCN neuroprotection during aging for the population at large. PMID:24932939

  17. Transgenerational Inheritance of Increased Fat Depot Size, Stem Cell Reprogramming, and Hepatic Steatosis Elicited by Prenatal Exposure to the Obesogen Tributyltin in Mice

    PubMed Central

    Chamorro-García, Raquel; Sahu, Margaret; Abbey, Rachelle J.; Laude, Jhyme; Pham, Nhieu

    2013-01-01

    Background: We have previously shown that exposure to tributyltin (TBT) modulates critical steps of adipogenesis through RXR/PPARγ and that prenatal TBT exposure predisposes multipotent mesenchymal stem cells (MSCs) to become adipocytes by epigenetic imprinting into the memory of the MSC compartment. Objective: We tested whether the effects of prenatal TBT exposure were heritable in F2 and F3 generations. Methods: We exposed C57BL/6J female mice (F0) to DMSO vehicle, the pharmaceutical obesogen rosiglitazone (ROSI), or TBT (5.42, 54.2, or 542 nM) throughout pregnancy via the drinking water. F1 offspring were bred to yield F2, and F2 mice were bred to produce F3. F1 animals were exposed in utero and F2 mice were potentially exposed as germ cells in the F1, but F3 animals were never exposed to the chemicals. We analyzed the effects of these exposures on fat depot weights, adipocyte number, adipocyte size, MSC programming, hepatic lipid accumulation, and hepatic gene expression in all three generations. Discussion: Prenatal TBT exposure increased most white adipose tissue (WAT) depot weights, adipocyte size, and adipocyte number, and reprogrammed MSCs toward the adipocyte lineage at the expense of bone in all three generations. Prenatal TBT exposure led to hepatic lipid accumulation and up-regulated hepatic expression of genes involved in lipid storage/transport, lipogenesis, and lipolysis in all three subsequent generations. Conclusions: Prenatal TBT exposure produced transgenerational effects on fat depots and induced a phenotype resembling nonalcoholic fatty liver disease through at least the F3 generation. These results show that early-life obesogen exposure can have lasting effects. PMID:23322813

  18. Daily consumption of orange-fleshed sweet potato for 60 days increased plasma β-carotene concentration but did not increase total body vitamin A pool size in Bangladeshi women.

    PubMed

    Jamil, Kazi M; Brown, Kenneth H; Jamil, Maleka; Peerson, Janet M; Keenan, Alison H; Newman, John W; Haskell, Marjorie J

    2012-10-01

    We assessed the effect of daily consumption of orange-fleshed sweet potatoes (OFSP), with or without added fat, on the vitamin A (VA) status of Bangladeshi women with low initial VA status. Women (n = 30/group) received one of the following for 6 d/wk over 10 wk: 1) 0 μg retinol activity equivalents (RAE)/d as boiled white-fleshed sweet potatoes (WFSP) and a corn oil capsule, 2) 600 μg RAE/d as boiled OFSP and a corn oil capsule, 3) fried OFSP and a corn oil capsule, or 4) boiled WFSP and a retinyl palmitate capsule in addition to their home diets. Plasma concentrations of retinol and β-carotene and total body VA pool size were assessed before and after the 60-d intervention. Initial and final plasma retinol concentrations (mean ± SD) were 0.75 ± 0.18 μmol/L and 0.84 ± 0.19 μmol/L, respectively (P = 0.31); final means did not differ by group. Initial and final plasma β-carotene concentrations were 0.10 ± 00 μmol/L and 0.18 ± 0.09 μmol/L, respectively (P < 0.0001); final mean plasma β-carotene concentrations were higher in groups that received OFSP (P < 0.0001), and final mean plasma β-carotene was marginally higher in the group that received fried OFSP compared with boiled OFSP (P = 0.07). Initial and final total body VA pool sizes were 0.060 ± 0.047 mmol and 0.091 ± 0.070 mmol, respectively (P = 0.05, n = 110) and did not differ by group. Despite an increase in plasma β-carotene concentration, the impact of OFSP on VA status appears to be limited in Bangladeshi women residing in a resource-poor community. PMID:22933750

  19. Drug-primed reinstatement of cocaine seeking in mice: increased excitability of medium-sized spiny neurons in the nucleus accumbens

    PubMed Central

    Ma, Yao-Ying; Henley, Sandy M.; Toll, Jeff; Jentsch, James D.; Evans, Christopher J.; Levine, Michael S.; Cepeda, Carlos

    2013-01-01

    To examine the mechanisms of drug relapse, we first established a model for cocaine IVSA (intravenous self-administration) in mice, and subsequently examined electrophysiological alterations of MSNs (medium-sized spiny neurons) in the NAc (nucleus accumbens) before and after acute application of cocaine in slices. Three groups were included: master mice trained by AL (active lever) pressings followed by IV (intravenous) cocaine delivery, yoked mice that received passive IV cocaine administration initiated by paired master mice, and saline controls. MSNs recorded in the NAc shell in master mice exhibited higher membrane input resistances but lower frequencies and smaller amplitudes of sEPSCs (spontaneous excitatory postsynaptic currents) compared with neurons recorded from saline control mice, whereas cells in the NAc core had higher sEPSCs frequencies and larger amplitudes. Furthermore, sEPSCs in MSNs of the shell compartment displayed longer decay times, suggesting that both pre- and postsynaptic mechanisms were involved. After acute re-exposure to a low-dose of cocaine in vitro, an AP (action potential)-dependent, persistent increase in sEPSC frequency was observed in both NAc shell and core MSNs from master, but not yoked or saline control mice. Furthermore, re-exposure to cocaine induced membrane hyperpolarization, but concomitantly increased excitability of MSNs from master mice, as evidenced by increased membrane input resistance, decreased depolarizing current to generate APs, and a more negative Thr (threshold) for firing. These data demonstrate functional differences in NAc MSNs after chronic contingent versus non-contingent IV cocaine administration in mice, as well as synaptic adaptations of MSNs before and after acute re-exposure to cocaine. Reversing these functional alterations in NAc could represent a rational target for the treatment of some reward-related behaviors, including drug addiction. PMID:24000958

  20. Increased reproductive effort results in male-biased offspring sex ratio: an experimental study in a species with reversed sexual size dimorphism.

    PubMed Central

    Kalmbach, E.; Nager, R. G.; Griffiths, R.; Furness, R. W.

    2001-01-01

    Adaptive sex-ratio theory predicts that parents should overproduce the more beneficial offspring sex. Based on a recent experimental study of lesser black-backed gulls, we tested this hypothesis with the great skua, Catharacta skua, a bird species closely related to gulls but where females are the larger sex. When in poor body condition, the gulls overproduced daughters, the smaller and more viable sex under those circumstances. To discriminate between a mandatory physiological overproduction of female (i.e. non-male) eggs versus the overproduction of the smaller and presumably more viable sex, we conducted an egg-removal experiment with the great skua. Since the males are smaller, larger size and being male are separated. Through egg removal we induced females to increase egg production effort. Eggs were sexed using a DNA-based technique. Manipulated pairs produced a significant male bias at the end of the extended laying sequence, while the sex ratio in the control group did not differ from unity. Our results present an example of facultative sex-ratio manipulation and support the hypothesis that in sexually dimorphic birds parents overproduce the smaller sex under adverse conditions. PMID:11600083

  1. Hybridisation is associated with increased fecundity and size in invasive taxa: meta-analytic support for the hybridisation-invasion hypothesis

    PubMed Central

    Hovick, Stephen M; Whitney, Kenneth D

    2014-01-01

    The hypothesis that interspecific hybridisation promotes invasiveness has received much recent attention, but tests of the hypothesis can suffer from important limitations. Here, we provide the first systematic review of studies experimentally testing the hybridisation-invasion (H-I) hypothesis in plants, animals and fungi. We identified 72 hybrid systems for which hybridisation has been putatively associated with invasiveness, weediness or range expansion. Within this group, 15 systems (comprising 34 studies) experimentally tested performance of hybrids vs. their parental species and met our other criteria. Both phylogenetic and non-phylogenetic meta-analyses demonstrated that wild hybrids were significantly more fecund and larger than their parental taxa, but did not differ in survival. Resynthesised hybrids (which typically represent earlier generations than do wild hybrids) did not consistently differ from parental species in fecundity, survival or size. Using meta-regression, we found that fecundity increased (but survival decreased) with generation in resynthesised hybrids, suggesting that natural selection can play an important role in shaping hybrid performance – and thus invasiveness – over time. We conclude that the available evidence supports the H-I hypothesis, with the caveat that our results are clearly driven by tests in plants, which are more numerous than tests in animals and fungi. PMID:25234578

  2. Feasibility of asymmetrical flow field-flow fractionation as a method for detecting protective antigen by direct recognition of size-increased target-captured nanoprobes.

    PubMed

    Shin, Kayeong; Choi, Jaeyeong; Cho, Jun-Haeng; Yoon, Moon-Young; Lee, Seungho; Chung, Hoeil

    2015-11-27

    Asymmetrical flow field-flow fractionation (AF4) was evaluated as a potential analytical method for detection of a protective antigen (PA), an Anthrax biomarker. The scheme was based on the recognition of altered AF4 retention through the generation of the size-increased Au nanoparticle probes as a result of PA binding, in which a PA-selective peptide was conjugated on the probe surface. In the visible absorption-based AF4 fractograms, the band position shifted to a longer retention time as the PA concentration increased due to the presence of probe bound with PAs. The shift was insignificant when the concentration was relatively low at 84.3pM. To improve sensitivity, two separate probes conjugated with two different peptides able to bind on different PA epitopes were used together. The band shift then became distinguishable even at 84.3pM of PA sample. The formation of larger PA-probe inter-connected species using the dual-probe system was responsible for the enhanced band shift. In parallel, the feasibility of surface-enhanced Raman scattering (SERS) as a potential AF4 detection method was also evaluated. In the off-line SERS fractogram constructed using fractions collected during AF4 separation, a band shift was also observed for the 84.3pM PA sample, and the band intensity was higher when using the dual-probe system. The combination of AF4 and SERS is promising for the detection of PA and will become a potential tool if the reproducibility of SERS measurement is improved. PMID:26482872

  3. Fully quantal calculation of H2 translation-rotation states in the (p-H2)2@51264 clathrate hydrate inclusion compound

    NASA Astrophysics Data System (ADS)

    Felker, Peter M.

    2014-11-01

    The quantal translation-rotation (TR) states of the (p-H2)2@51264 clathrate hydrate inclusion compound have been computed. The ten-dimensional problem (in the rigid-cage and rigid-H2 approximation) is solved by first approximating the H2 moieties as spherically symmetric and solving for their 6D translational eigenstates. These are then combined with H2 free rotational states in a product basis that is used to diagonalize the full TR hamiltonian. The computed low-energy eigenstates have translational components that are essentially identical to the 6D translational eigenstates and rotational components that are 99.9% composed of rotationally unexcited H2 moieties. In other words, TR coupling is minimal for the low-energy states of the species. The low-energy level structure is found to be substantially more congested than that of the more tightly packed (p-H2)4@51264 clathrate species. The level structure is also shown to be understandable in terms of a model of (H2)2 as a semirigid diatomic species consisting of two spherically symmetric H2 pseudo-atoms.

  4. Dosimetric response of variable-size cavities in photon-irradiated media and the behaviour of the Spencer-Attix cavity integral with increasing Δ.

    PubMed

    Kumar, Sudhir; Deshpande, Deepak D; Nahum, Alan E

    2016-04-01

    Cavity theory is fundamental to understanding and predicting dosimeter response. Conventional cavity theories have been shown to be consistent with one another by deriving the electron (+positron) and photon fluence spectra with the FLURZnrc user-code (EGSnrc Monte-Carlo system) in large volumes under quasi-CPE for photon beams of 1 MeV and 10 MeV in three materials (water, aluminium and copper) and then using these fluence spectra to evaluate and then inter-compare the Bragg-Gray, Spencer-Attix and 'large photon' 'cavity integrals'. The behaviour of the 'Spencer-Attix dose' (aka restricted cema), D S-A(▵), in a 1-MeV photon field in water has been investigated for a wide range of values of the cavity-size parameter ▵: D S-A(▵) decreases far below the Monte-Carlo dose (D MC) for ▵ greater than  ≈  30 keV due to secondary electrons with starting energies below ▵ not being 'counted'. We show that for a quasi-scatter-free geometry (D S-A(▵)/D MC) is closely equal to the proportion of energy transferred to Compton electrons with initial (kinetic) energies above ▵, derived from the Klein-Nishina (K-N) differential cross section. (D S-A(▵)/D MC) can be used to estimate the maximum size of a detector behaving as a Bragg-Gray cavity in a photon-irradiated medium as a function of photon-beam quality (under quasi CPE) e.g. a typical air-filled ion chamber is 'Bragg-Gray' at (monoenergetic) beam energies  ⩾260 keV. Finally, by varying the density of a silicon cavity (of 2.26 mm diameter and 2.0 mm thickness) in water, the response of different cavity 'sizes' was simulated; the Monte-Carlo-derived ratio D w/D Si for 6 MV and 15 MV photons varied from very close to the Spencer-Attix value at 'gas' densities, agreed well with Burlin cavity theory as ρ increased, and approached large photon behaviour for ρ  ≈  10 g cm(-3). The estimate of ▵ for the Si cavity was improved by incorporating a Monte-Carlo-derived correction for

  5. Sintered anorganic bone graft increases autocrine expression of VEGF, MMP-2 and MMP-9 during repair of critical-size bone defects.

    PubMed

    Rocha, Caroline Andrade; Cestari, Tania Mary; Vidotti, Hugo Alberto; de Assis, Gerson Francisco; Garlet, Gustavo Pompermaier; Taga, Rumio

    2014-08-01

    This study aimed to evaluate morphometrically the bone formation and immunohistochemically the expression of vascular endothelial growth factor (VEGF) and metalloproteinase (MMP)-2 and -9 during the healing of critical-size defects treated with sintered anorganic bone (sAB). The 8-mm diameter full-thickness trephine defects created in the parietal bones of rats were filled with sAB (test group) or blood clot (CSD-control group). At 7, 14, 21, 30, 90 and 180 days postoperatively (n = 6/period) the volume of newly formed bone and total number of immunolabeled cells (Ntm) for each protein were determined. Bone formation was smaller and faster in the CSD-control group, stabilizing at 21 days (6.74 mm(3)). The peaks of VEGF, MMP-2 and MMP-9 occurred at 7 and 14 days in fibroblasts and osteoblasts, with mean reduction of 0.80 time at 21 days, keeping constant until 180 days. In the test group, sAB provided continuous bone formation between particles throughout all periods. The peak of MMP-2 was observed at 7-14 days in connective tissue cells and for VEGF and MMP-9 at 30 days in osteoblasts and osteocytes. Ntm for VEGF, MMP-2 and MMP-9 were in average, respectively, 3.70, 2.03 and 5.98 times higher than in the control group. At 180 days, newly formed bone (22.9 mm(3)) was 3.74 times greater in relation to control. The physical and chemical properties of sAB allow increased autocrine expression of VEGF, MMP-2 and MMP-9, favoring bone formation/remodeling with very good healing of cranial defects when compared to natural repair in the CSD-control. PMID:24482159

  6. Dosimetric response of variable-size cavities in photon-irradiated media and the behaviour of the Spencer-Attix cavity integral with increasing Δ

    NASA Astrophysics Data System (ADS)

    Kumar, Sudhir; Deshpande, Deepak D.; Nahum, Alan E.

    2016-04-01

    Cavity theory is fundamental to understanding and predicting dosimeter response. Conventional cavity theories have been shown to be consistent with one another by deriving the electron (+positron) and photon fluence spectra with the FLURZnrc user-code (EGSnrc Monte-Carlo system) in large volumes under quasi-CPE for photon beams of 1 MeV and 10 MeV in three materials (water, aluminium and copper) and then using these fluence spectra to evaluate and then inter-compare the Bragg-Gray, Spencer-Attix and ‘large photon’ ‘cavity integrals’. The behaviour of the ‘Spencer-Attix dose’ (aka restricted cema), D S-A(▵), in a 1-MeV photon field in water has been investigated for a wide range of values of the cavity-size parameter ▵: D S-A(▵) decreases far below the Monte-Carlo dose (D MC) for ▵ greater than  ≈  30 keV due to secondary electrons with starting energies below ▵ not being ‘counted’. We show that for a quasi-scatter-free geometry (D S-A(▵)/D MC) is closely equal to the proportion of energy transferred to Compton electrons with initial (kinetic) energies above ▵, derived from the Klein-Nishina (K-N) differential cross section. (D S-A(▵)/D MC) can be used to estimate the maximum size of a detector behaving as a Bragg-Gray cavity in a photon-irradiated medium as a function of photon-beam quality (under quasi CPE) e.g. a typical air-filled ion chamber is ‘Bragg-Gray’ at (monoenergetic) beam energies  ⩾260 keV. Finally, by varying the density of a silicon cavity (of 2.26 mm diameter and 2.0 mm thickness) in water, the response of different cavity ‘sizes’ was simulated; the Monte-Carlo-derived ratio D w/D Si for 6 MV and 15 MV photons varied from very close to the Spencer-Attix value at ‘gas’ densities, agreed well with Burlin cavity theory as ρ increased, and approached large photon behaviour for ρ  ≈  10 g cm-3. The estimate of ▵ for the Si cavity was improved by incorporating a Monte

  7. A Proton Beam Therapy System Dedicated to Spot-Scanning Increases Accuracy with Moving Tumors by Real-Time Imaging and Gating and Reduces Equipment Size

    PubMed Central

    Shimizu, Shinichi; Miyamoto, Naoki; Matsuura, Taeko; Fujii, Yusuke; Umezawa, Masumi; Umegaki, Kikuo; Hiramoto, Kazuo; Shirato, Hiroki

    2014-01-01

    Purpose A proton beam therapy (PBT) system has been designed which dedicates to spot-scanning and has a gating function employing the fluoroscopy-based real-time-imaging of internal fiducial markers near tumors. The dose distribution and treatment time of the newly designed real-time-image gated, spot-scanning proton beam therapy (RGPT) were compared with free-breathing spot-scanning proton beam therapy (FBPT) in a simulation. Materials and Methods In-house simulation tools and treatment planning system VQA (Hitachi, Ltd., Japan) were used for estimating the dose distribution and treatment time. Simulations were performed for 48 motion parameters (including 8 respiratory patterns and 6 initial breathing timings) on CT data from two patients, A and B, with hepatocellular carcinoma and with clinical target volumes 14.6 cc and 63.1 cc. The respiratory patterns were derived from the actual trajectory of internal fiducial markers taken in X-ray real-time tumor-tracking radiotherapy (RTRT). Results With FBPT, 9/48 motion parameters achieved the criteria of successful delivery for patient A and 0/48 for B. With RGPT 48/48 and 42/48 achieved the criteria. Compared with FBPT, the mean liver dose was smaller with RGPT with statistical significance (p<0.001); it decreased from 27% to 13% and 28% to 23% of the prescribed doses for patients A and B, respectively. The relative lengthening of treatment time to administer 3 Gy (RBE) was estimated to be 1.22 (RGPT/FBPT: 138 s/113 s) and 1.72 (207 s/120 s) for patients A and B, respectively. Conclusions This simulation study demonstrated that the RGPT was able to improve the dose distribution markedly for moving tumors without very large treatment time extension. The proton beam therapy system dedicated to spot-scanning with a gating function for real-time imaging increases accuracy with moving tumors and reduces the physical size, and subsequently the cost of the equipment as well as of the building housing the equipment. PMID

  8. Daily consumption of orange-fleshed sweet potato with added fat tends to increase total body vitamin A pool size in vitamin A depleted Bangladeshi women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We assessed the affect of daily consumption of orange-fleshed sweet potato (OFSP), with or without added fat, on the total body vitamin A (VA) pool size of Bangladeshi women with low initial VA status. Women (n=120) received for 60d either 1) 0 µg RAE/d as boiled white-fleshed sweet potatoes (WFSP) ...

  9. Increased pigment and lipid content, lipid variety, and cell and population size of the microalgae Chlorella spp. when co-immobilized in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense.

    PubMed

    de-Bashan, Luz E; Bashan, Yoav; Moreno, Manuel; Lebsky, Vladimir K; Bustillos, Jose J

    2002-06-01

    Three strains of the freshwater microalgae used for wastewater treatment, Chlorella vulgaris and Chlorella sorokiniana co-immobilized separately in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense Cd, resulted in significant changes in microalgal-population size, cell size, cell cytology, pigment, lipid content, and the variety of fatty acids produced in comparison with microalgae immobilized in alginate without the bacterium. Cells of C. vulgaris UTEX 2714 did not change in size, but the population size within the beads significantly increased. On the other hand, C. vulgaris UTEX 395 cells grew 62% larger, but their numbers did not increase. The population of C. sorokiniana UTEX 1602 increased, but not their cell size. The content of pigments chlorophyll a and b, lutein, and violoaxanthin increased in all microalgal species. The lipid content also significantly increased in all three strains, and the number of different fatty acids in the microalgae increased from four to eight. This study indicates that the microalgae-growth-promoting bacterium induced significant changes in the metabolism of the microalgae. PMID:12166678

  10. Probability of double-strand breaks in genome-sized DNA by {gamma}-ray decreases markedly as the DNA concentration increases

    SciTech Connect

    Shimobayashi, Shunsuke F.; Iwaki, Takafumi; Mori, Toshiaki; Yoshikawa, Kenichi

    2013-05-07

    By use of the single-molecule observation, we count the number of DNA double-strand breaks caused by {gamma}-ray irradiation with genome-sized DNA molecules (166 kbp). We find that P{sub 1}, the number of double-strand breaks (DSBs) per base pair per unit Gy, is nearly inversely proportional to the DNA concentration above a certain threshold DNA concentration. The inverse relationship implies that the total number of DSBs remains essentially constant. We give a theoretical interpretation of our experimental results in terms of attack of reactive species upon DNA molecules, indicating the significance of the characteristics of genome-sized giant DNA as semiflexible polymers for the efficiency of DSBs.