bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intergenomic epistasis causes asynchronous hatch times in whitefish hybrids, but only when parental ecotypes differ
Authors: WOODS P. J. , MÜLLER R. , SEEHAUSEN O. 
Published: October 2009

AbstractSupport for the theory of ecological speciation requires evidence for ecological divergence between species which directly or indirectly causes reproductive isolation. This study investigates effects of ecological vs. genetic disparity of parental species on the presence of endogenous selection (deformation and mortality rates) and potential sources of exogenous selection (growth rates and hatch timing) on hybrids. Hybrid embryonic development is analysed in a common‐garden full‐sib cross of three species belonging to two different ecotypes within theCoregonus lavaretusspecies flock in the central Alpine region of Europe. Although hatch timing was similar across the three species, embryonic growth rates and egg sizes differed between ecotypes. This led to a mismatch between embryonic growth rate and egg size in hybrid crosses that reveals epistasis between the maternal and embryonic genomes and transgressive hatch times that were asynchronous with control crosses. A strong constraint of egg size to embryo size at late development was also evident. We argue that this demonstrates potential for coadaptation of a maternal trait (egg size) with offspring growth rate to be an important source of selection against hybridization between ecotypes with different egg sizes. Implications for the measurement and quantification of early life‐history traits affected by this additive relationship, such as hatch day and larval size, are also discussed.
Inbreeding depression in an asexual population of Mimulus guttatus
Authors: MARRIAGE T. N. , KELLY J. K. 
Published: October 2009

AbstractThe reproductive mechanism, that is whether an organism outcrosses, selfs or asexually reproduces, has a substantial impact on the amount and pattern of genetic variation. In this study, we estimate genetic variation and genetic load for a predominately asexual population of Mimulus guttatus, and then compare our results to other studies of predominately sexually reproducing (outcrossing and selfing) populations of M. guttatus. The asexual population had low levels of heterozygosity (He = 0.03) and low (but significantly non‐zero) inbreeding load, especially when compared with other M. guttatus populations. This differs greatly from the sexual populations of Mimulus that display substantial inbreeding depression. We discuss a variety of reasons why we see such low load in this study and suggest future research projects to further explore the questions.
PEP‐Carboxylase Activity: A Comparison of its Role in a C4 and a C3 Species Under Salt Stress
Authors: Hatzig S. , Kumar A. , Neubert A. , Schubert S. 
Published: October 2009

AbstractIn our experiments, we found an increase of PEP‐carboxylase activity in young shoots of maize under salt stress. Within this study, several analyses were carried out to identify the function of this enhanced enzyme activity during salt stress. In our first experiment, we analysed plants of the salt‐resistant maize hybrid SR 03 (Zea mays L.), whereas in the second experiment, we compared maize and wheat (Triticum aestivum L. cv. Thasos), which were grown under two different light intensities for 20 days. In the saline treatments, NaCl was applied up to 100 mm, while control plants grew under non‐saline conditions (1 mm NaCl). Analyses of shoot fresh weight revealed a comparable reduction for both genotypes and suggested salt resistance at a similar level. Analyses of sugar concentrations showed an increase in the saline treatment for both genotypes independent of the light intensity. Results for sucrose concentrations led to the conclusion that an increase in PEP‐carboxylase activity was not required for sugar metabolism. Independent of light intensity, alkalinity and malate concentrations were decreased only in wheat. It can be concluded that an enhancement of PEP‐carboxylase activity in young shoots of maize supports organic acid metabolism under salt stress.
Relationship between Carbon Isotope Discrimination, Mineral Content and Gas Exchange Parameters in Vegetative Organs of Wheat Grown under Three Different Water Regimes
Authors: Zhu L. , Li S. H. , Liang Z. S. , Xu X. , Li Y. 
Published: October 2009

AbstractCarbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of high cost for Δ analysis, attempts have been made to identify alternative screening criteria. Ash content (ma) has been proposed as an alternative criterion for Δ in wheat and barley. A pot experiment was conducted to analyse the relationship between Δ, mineral content and gas exchange parameters in seedlings and leaves of bread wheat (Triticum aestivum L.). Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate (T3), intermediate (T2) and severe drought (T1) stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity respectively. Δ and ma in seedlings and leaves showed significant differences among the three water treatments. Significant positive correlations were found between Δ and ma in seedlings and leaves at elongation and anthesis stages in severe drought stress (T1). Δ was negatively associated with potassium (K) content in intermediate drought stress (T2) and positively with magnesium (Mg) content in T2 and T3 (moderate drought stress) in flag leaf at anthesis. There were negative correlations between Δ and single‐leaf intrinsic water‐use efficiency (WT) in T2 and T3 at anthesis stage. Stronger positive associations were noted between Δ and stomatal conductance (gs) in T1 and T2 than in T3 at anthesis. These results suggested that Δ is a good trait as an indirect selection criterion for genotypic improvement in transpiration efficiency, while ma is a possible alternative criterion of Δ in wheat vegetative organs, especially in stressed environments. Significant association was found between Δ and K, Mg and Ca contents that would merit being better investigated.
Influence of non‐crop plants on stink bug (Hemiptera: Pentatomidae) and natural enemy abundance in tomatoes
Authors: Pease C. G. , Zalom F. G. 
Published: October 2009

AbstractWe investigated the effects of weed hosts on stink bug density and damage (Euschistus conspersus Uhler and Thyanta pallidovirens Stal), and a nectar bearing plant on natural enemies of stink bugs in the Sacramento Valley of California. Stink bug density and fruit damage were evaluated in processing tomatoes adjacent to weedy and cultivated borders. The density of E. conspersus was significantly greater in tomatoes adjacent to weedy borders in July but not during August/September. Thyanta pallidovirens was less abundant overall (19%), but was found in significantly greater densities adjacent to cultivated borders in July but not in August/September. Mean percent fruit damage by stink bugs was greater adjacent to the weedy border than the cultivated border, but this difference was not significant. Stink bug egg parasitism and generalist predator density were evaluated in fresh market tomatoes adjacent to a sweet alyssum (Lobularia maritima L.) border and an unplanted control border at three sites. Egg parasitism was significantly greater in the alyssum treatment for the 9–12 September sampling period. Jalysus wickhami VanDuzee (Hemiptera: Berytidae) density was significantly greater in the alyssum treatment in mid‐June. No other significant differences in predator populations were detected. Results of these two studies show that habitat manipulations have the potential to reduce densities of E. conspersus in tomato, the first step in developing a farmscape management plan for stink bug control.
Asymptotic thermal and residual stress distributions due to transient thermal loads
Authors: FERRO P. , PETRONE N. 
Published: October 2009

ABSTRACTThe paper deals with the development of thermal and residual stress distributions arising from the solidification of a fusion zone near a V‐notch tip. A set of numerical solutions of the problem was carried out under the hypothesis of generalized plane strain conditions by means of SYSWELD code. The intensity of the thermal and residual asymptotic stress fields at the sharp V‐notch tip was studied for a given V‐notch specimen geometry and a predefined fusion zone dimension after simulations on materials with different thermal, mechanical and phase transformation properties and after changing the clamping conditions at the specimen's boundary. The results were compared in terms of the elastic or elastic‐plastic notch stress intensity factors giving a contribution to the interpretation of the experimental behaviour of welded joint.
Fatigue crack growth, physical understanding and practical application
Authors: SCHIJVE J. 
Published: October 2009

ABSTRACTThe paper presents a discussion on two problems associated with fatigue crack growth in aluminium alloys. First, the application of the similarity approach to crack growth prediction in specimens and structures of aluminium alloys is discussed. The significance of similarity conditions is emphasized and the K‐dominated zone is briefly addressed. Secondly, the significance of water vapour for fatigue crack growth in aluminium alloy is reported with a case history of subsurface crack initiation and crack growth in vacuum. Some comments are presented on physical understanding and practical applications.
Pharmaco‐resistant seizures: self‐triggering capacity, scale‐free properties and predictability?
Authors: Osorio Ivan , Frei Mark G. , Sornette Didier , Milton John 
Published: October 2009

AbstractRelevant and timely questions such as regarding the predictability of seizures and their capacity to trigger more seizures remain the subject of debate in epileptology. The present study endeavors to gain insight into these dynamic issues by adopting a non‐reductionist approach and via the use of mathematical tools. Probability distribution functions of seizure energies and inter‐seizure intervals and the probability of seizure occurrence conditional upon the time elapsed from the previous seizure were estimated from prolonged recordings from subjects with pharmaco‐resistant seizures, undergoing surgical evaluation, on reduced doses of or on no medications. The energy and inter‐seizure interval distributions for pharmaco‐resistant seizures, under the prevailing study conditions, are governed by power laws (‘scale‐free’ behavior). Pharmaco‐resistant seizures tend to occur in clusters and the time to the next seizure increases with the duration of the seizure‐free interval since the last one. However, characteristic size energy probability density functions were found in a few subjects. These findings suggests that: (i) pharmaco‐resistant seizures have an inherent self‐triggering capacity; (ii) their time of occurrence and intensity may be predictable in light of the existence of power law distributions and of their self‐triggering capacity; and (iii) their lack of typical size and duration (scale‐free), features upon which their classification into ictal or interictal is largely based, may be inadequate/insufficient classifiers.
Further genetic evidence implicates the vasopressin system in childhood‐onset mood disorders
Authors: Dempster Emma L. , Burcescu Irina , Wigg Karen , Kiss Eniko , Baji Ildiko , Gadoros Julia , Tamás Zsuzsanna , Kapornai Krisztina , Daróczy Gabriella , Kennedy James L. , Vetró Agnes , Kovacs Maria , Barr Cathy L. ,   The International Consortium for Childhood‐Onset Mood Disorders
Published: October 2009

AbstractStudies in both animals and humans advocate a role for the vasopressin (AVP) system in the aetiology of depressive symptoms. Attention has particularly focused on the role of AVP in the overactivation of the hypothalamic‐pituitary‐adrenal (HPA)‐axis in mood disorders. Elevated AVP plasma levels have been found in mood disorder patients, which are often positively correlated with the severity of symptoms. We recently reported an association between childhood‐onset mood disorders (COMD) and polymorphisms in the receptor responsible for the AVP‐mediated activation of the HPA‐axis (AVPR1B). As genetic variation in the vasopressinergic system could provide a mechanism to explain the endocrine alterations observed in mood disorders, we investigated other genes in this system. The gene encoding AVP is the strongest candidate, particularly as genetic variation in this gene in rodents is associated with anxiety‐related behaviours. Six single‐nucleotide polymorphisms (SNPs) were genotyped across the AVP gene in a sample comprised of 586 Hungarian nuclear families ascertained through affected probands with a diagnosis of COMD. In addition, AVP coding and putative regulatory regions were screened for mutations using denaturing high‐performance liquid chromatography. One SNP, 3′ to the AVP, gene reached significance (P = 0.03), as did the overtransmission of a five‐marker haplotype with a frequency of 22% (P = 0.0001). The subsequent mutation screen failed to identify any putative functional polymorphisms. The outcome of this study, combined with our previous association between COMD and AVPR1B, implicates genetic variation in vasopressinergic genes in mediating vulnerability to COMD.
Differential effects of anesthetics on cocaine’s pharmacokinetic and pharmacodynamic effects in brain
Authors: Du Congwu , Tully Melissa , Volkow Nora D. , Schiffer Wynne K. , Yu Mei , Luo Zhongchi , Koretsky Alan P. , Benveniste Helene 
Published: October 2009

AbstractMost studies of the effect of cocaine on brain activity in laboratory animals are preformed under anesthesia, which could potentially affect the physiological responses to cocaine. Here we assessed the effects of two commonly used anesthetics [α‐chloralose (α‐CHLOR) and isofluorane (ISO)] on the effects of acute cocaine (1 mg/kg i.v.) on cerebral blood flow (CBF), cerebral blood volume (CBV), and tissue hemoglobin oxygenation (StO2) using optical techniques and cocaine’s pharmacokinetics (PK) and binding in the rat brain using (PET) and [11C]cocaine. We showed that acute cocaine at a dose abused by cocaine abusers decreased CBF, CBV and StO2in rats anesthetized with ISO, whereas it increased these parameters in rats anesthetized with α‐CHLOR. Importantly, in ISO‐anesthetized animals cocaine‐induced changes in CBF and StO2were coupled, whereas for α‐CHLOR these measures were uncoupled. Moreover, the clearance of [11C]cocaine from the brain was faster for ISO (peak half‐clearance 15.8 ± 2.8 min) than for α‐CHLOR (27.5 ± 0.6 min), and the ratio of specific to non‐specific binding of [11C]cocaine in the brain was higher for ISO‐ (3.37 ± 0.32) than for α‐CHLOR‐anesthetized rats (2.24 ± 0.4). For both anesthetics, cocaine‐induced changes in CBF followed the fast uptake of [11C]cocaine in the brain (peaking at ∼2.5–4 min), but only for ISO did the duration of the CBV and StO2changes correspond to the rate of [11C]cocaine’s clearance from the brain. These results demonstrate that anesthetics influence cocaine’s hemodynamic and metabolic changes in the brain, and its binding and PK, which highlights the need to better understand the interactions between anesthetics and pharmacological challenges in brain functional imaging studies.
Segregation of short‐wavelength‐sensitive (S) cone signals in the macaque dorsal lateral geniculate nucleus
Authors: Roy Sujata , Jayakumar Jaikishan , Martin Paul R. , Dreher Bogdan , Saalmann Yuri B. , Hu Daping , Vidyasagar Trichur R. 
Published: October 2009

AbstractAn important problem in the study of the mammalian visual system is whether functionally different retinal ganglion cell types are anatomically segregated further up along the central visual pathway. It was previously demonstrated that, in a New World diurnal monkey (marmoset), the neurones carrying signals from the short‐wavelength‐sensitive (S) cones [blue–yellow (B/Y)‐opponent cells] are predominantly located in the koniocellular layers of the dorsal lateral geniculate nucleus (LGN), whereas the red–green (R/G)‐opponent cells carrying signals from the medium‐ and long‐wavelength‐sensitive cones are segregated in the parvocellular layers. Here, we used extracellular single‐unit recordings followed by histological reconstruction to investigate the distribution of color‐selective cells in the LGN of the macaque, an Old World diurnal monkey. Cells were classified using cone‐isolating stimuli to identify their cone inputs. Our results indicate that the majority of cells carrying signals from S‐cones are located either in the koniocellular layers or in the ‘koniocellular bridges’ that fully or partially span the parvocellular layers. By contrast, the R/G‐opponent cells are located in the parvocellular layers. We conclude that anatomical segregation of B/Y‐ and R/G‐opponent afferent signals for color vision is common to the LGNs of New World and Old World diurnal monkeys.
Early olfactory experience modifies neural activity in the antennal lobe of a social insect at the adult stage
Authors: Arenas A. , Giurfa M. , Farina W. M. , Sandoz J. C. 
Published: October 2009

AbstractIn the antennal lobe (AL), the first olfactory centre of the insect brain, odorants are represented as spatiotemporal patterns of glomerular activity. Whether and how such patterns are modified in the long term after precocious olfactory experiences (i.e. in the first days of adulthood) remains unknown. To address this question, we used in vivo optical imaging of calcium activity in the antennal lobe of 17‐day‐old honeybees which either experienced an odorant associated with sucrose solution 5–8 days after emergence or were left untreated. In both cases, we imaged neural responses to the learned odor and to three novel odors varying in functional group and carbon‐chain length. Two different odor concentrations were used. We also measured behavioral responses of 17‐day‐old honeybees, treated and untreated, to these stimuli. We show that precocious olfactory experience increased general odor‐induced activity and the number of activated glomeruli in the adult AL, but also affected qualitative odor representations, which appeared shifted in the neural space of treated animals relative to control animals. Such effects were not limited to the experienced odor, but were generalized to other perceptually similar odors. A similar trend was found in behavioral experiments, in which increased responses to the learned odor extended to perceptually similar odors in treated bees. Our results show that early olfactory experiences have long‐lasting effects, reflected in behavioral responses to odorants and concomitant neural activity in the adult olfactory system.
GABAergic signaling induces divergent neuronal Ca2+ responses in the suprachiasmatic nucleus network
Authors: Irwin Robert P. , Allen Charles N. 
Published: October 2009

AbstractIntercellular communication between γ‐aminobutyric acid (GABA)ergic suprachiasmatic nucleus (SCN) neurons facilitates light‐induced phase changes and synchronization of individual neural oscillators within the SCN network. We used ratiometric Ca2+ imaging techniques to record changes in the intracellular calcium concentration ([Ca2+]i) to study the role of GABA in interneuronal communication and the response of the SCN neuronal network to optic nerve stimulations that mimic entraining light signals. Stimulation of the retinohypothalamic tract (RHT) evoked divergent Ca2+ responses in neurons that varied regionally within the SCN with a pattern that correlated with those evoked by pharmacological GABA applications. GABAA and GABAB receptor agonists and antagonists were used to evaluate components of the GABA‐induced changes in [Ca2+]i. Application of the GABAA receptor antagonist gabazine induced changes in baseline [Ca2+]i in a direction opposite to that evoked by GABA, and similarly altered the RHT stimulation‐induced Ca2+ response. GABA application induced Ca2+ responses varied in time and region within the SCN network. The NKCC1 cotransporter blocker, bumetanide, and L‐type calcium channel blocker, nimodipine, attenuated the GABA‐induced rise of [Ca2+]i. These results suggest that physiological GABA induces opposing effects on [Ca2+]i based on the chloride equilibrium potential, and may play an important role in neuronal Ca2+ balance, synchronization and modulation of light input signaling in the SCN network.
N‐methyl‐d‐aspartate receptor‐ and metabotropic glutamate receptor‐dependent long‐term depression are differentially regulated by the ubiquitin‐proteasome system
Authors: Citri Ami , Soler‐Llavina Gilberto , Bhattacharyya Samarjit , Malenka Robert C. 
Published: October 2009

AbstractLong‐term depression (LTD) in CA1 pyramidal neurons can be induced by activation of either N‐methyl‐d‐aspartate receptors (NMDARs) or metabotropic glutamate receptors (mGluRs), both of which elicit changes in synaptic efficacy through α‐amino‐3‐hydroxyl‐5‐methyl‐4‐isoxazole‐propionate receptor (AMPAR) endocytosis. To address the role of the ubiquitin‐proteasome system in regulating AMPAR endocytosis during these forms of LTD, we examined the effects of pharmacological inhibitors of proteasomal degradation and protein ubiquitination on endocytosis of glutamate receptor 1 (GluR1) ‐containing AMPARs in dissociated rat hippocampal cultures as well as LTD of excitatory synaptic responses in acute rat hippocampal slices. Our findings suggest that the contribution of the ubiquitin‐proteasome system to NMDAR‐induced vs. mGluR‐induced AMPAR endocytosis and the consequent LTD differs significantly. NMDAR‐induced AMPAR endocytosis and LTD occur independently of proteasome function but appear to depend, at least in part, on ubiquitination. In contrast, mGluR‐induced AMPAR endocytosis and LTD are enhanced by inhibition of proteasomal degradation, as well as by the inhibitor of protein ubiquitination. Furthermore, the decay of mGluR‐induced membrane depolarization and Erk activation is delayed following inhibition of either ubiquitination or proteasomal degradation. These results suggest that, although NMDAR‐dependent LTD may utilize ubiquitin as a signal for AMPAR endocytosis, mGluR‐induced signaling and LTD are limited by a feedback mechanism that involves the ubiquitin‐proteasome system.