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Effects Only (effects + only)
Selected AbstractsLOCAL HETEROZYGOSITY-FITNESS CORRELATIONS WITH GLOBAL POSITIVE EFFECTS ON FITNESS IN THREESPINE STICKLEBACKEVOLUTION, Issue 8 2006Mélissa Lieutenant-Gosselin Abstract The complex interactions between genetic diversity and evolution have important implications in many biological areas including conservation, speciation, and mate choice. A common way to study these interactions is to look at heterozygosity-fitness correlations (HFCs). Until recently, HFCs based on noncoding markers were believed to result primarily from global inbreeding effects. However, accumulating theoretical and empirical evidence shows that HFCs may often result from genes being linked to the markers used (local effect). Moreover, local effect HFCs could differ from global inbreeding effects in their direction and occurrence. Consequently, the investigation of the structure and consequences of local HFCs is emerging as a new important goal in evolutionary biology. In this study of a wild threespine stickleback (Gasterosteus aculeatus) population, we first tested the presence of significant positive or negative local effects of heterozygosity at 30 microsatellites loci on five fitness components: survival, mating success, territoriality, length, and body condition. Then, we evaluated the direction and shape of total impact of local HFCs, and estimated the magnitude of the impacts on fitness using regression coefficients and selection differentials. We found that multilocus heterozygosity was not a reliable estimator of individual inbreeding coefficient, which supported the relevance of single-locus based analyses. Highly significant and temporally stable local HFCs were observed. These were mainly positive, but negative effects of heterozygosity were also found. Strong and opposite effects of heterozygosity are probably present in many populations, but may be blurred in HFC analyses looking for global effects only. In this population, both negative and positive HFCs are apparently driving mate preference by females, which is likely to contribute to the maintenance of both additive and nonadditive genetic variance. [source] Comparative study on the antimicrobial activities of different sandalwood essential oils of various originFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2006Leopold Jirovetz Abstract In total, eight samples of different sandalwoods [Amyris balsamifera L., Santalum album L. and Santalum spicatum (R.Br.) A.DC.] and a mixture of , - and , -santalols, as well as eugenol as reference compound, were tested by an agar dilution and agar diffusion method for their antimicrobial activities against the yeast Candida albicans, the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. The main compounds of each essential oil were investigated by gas chromatographic,spectroscopic (GC-FID and GC,MS) and ,olfactory methods to obtain information about the inßuence of these volatiles on the observed antimicrobial effects. For the santalol mixture, as well as for one S. album and one S. spicatum sample with moderate concentrations of santalols, antimicrobial activity was found against all the strains used. The A. balsamifera sample, containing only a small quantity of , -santalol and nearly no , -santalol, showed high effects only against Klebsiella pneumoniae, while against the other strains weak or no activity was observed. Therefore, santalols in medium and/or high concentrations in sandalwood oils show a significant inßuence on antimicrobial potential in such natural products. Copyright © 2006 John Wiley & Sons, Ltd. [source] Macroecology, global change and the shadow of forgotten ancestorsGLOBAL ECOLOGY, Issue 1 2008José Alexandre Felizola Diniz-Filho ABSTRACT Many recent studies have evaluated how global changes will affect biodiversity, and have mainly focused on how to develop conservation strategies to avoid, or at least minimize, extinctions due to shifts in suitable habitats for the species. However, these complex potential responses might be in part structured in phylogeny, because of the macroecological traits underlying them. In this comment, we review recent analytical developments in phylogenetic comparative methods that can be used to understand patterns of trait changes under environmental change. We focus on a partial regression approach that allows for partitioning the variance of traits into a fraction attributed to a pure ecological component, a fraction attributed to phylogenetically structured environmental variation (niche conservatism) and a fraction that may be attributed to phylogenetic effects only. We then develop a novel interpretation for linking these components for multiple traits with potential responses of species to global environmental change (i.e. adaptation, range shifts or extinctions). We hope that this interpretation will stimulate further research linking evolutionary components of multiple traits with broad-scale environmental changes. [source] The Role of Cardiac Tissue Alignment in Modulating Electrical FunctionJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2007CHIUNG-YIN CHUNG M.S. Introduction:,Most cardiac arrhythmias are associated with pathology-triggered ion channel remodeling. However, multicellular effects, for example, exaggerated anisotropy and altered cell-to-cell coupling, can also indirectly affect action potential morphology and electrical stability via changed electrotonus. These changes are particularly relevant in structural heart disease, including hypertrophy and infarction. Recent computational studies showed that electrotonus factors into stability by altering dynamic properties (restitution). We experimentally address the question of how cell alignment and connectivity alter tissue function and whether these effects depend on the direction of wave propagation. Methods and Results:,We show that cardiac cell arrangement can alter electrical stability in an in vitro cardiac tissue model by mechanisms both dependent and independent of the direction of wave propagation, and local structural remodeling can be felt beyond a space constant. Notably, restitution of action potential duration (APD) and conduction velocity was significantly steepened in the direction of cell alignment. Furthermore, prolongation of APD and calcium transient duration was found in highly anisotropic cell networks, both for longitudinal and transverse propagation. This is in contrast to expected correlation between wave propagation direction and APD based on electrotonic effects only, but is consistent with our findings of increased cell size and secretion of atrial natriuretic factor, a hypertrophy marker, in the aligned structures. Conclusion:,Our results show that anisotropic structure is a potent modulator of electrical stability via electrotonus and molecular signaling. Tissue alignment must be taken into account in experimental and computational models of arrhythmia generation and in designing effective treatment therapies. [source] Litter effects on plant regeneration in arid lands: a complex balance between seed retention, seed longevity and soil,seed contactJOURNAL OF ECOLOGY, Issue 4 2005JOSÉ L. ROTUNDO Summary 1The recovery of rare, threatened plant populations can sometimes be achieved through modification of the disturbance regime. Accumulation of litter is likely to follow a reduction in grazing pressure and we therefore examine its effects on seedling recruitment of a threatened species in a temperate arid rangeland. 2We studied the effects of litter on seed longevity in the field and performed glasshouse and field experiments with natural and plastic litter to assess their physical and biological/chemical nature. Seeds were sown on the soil surface, buried or within the litter layer. Published data on spatial distribution of seeds were used to calculate the net effect of litter on seedling recruitment. 3Litter increased seed longevity. In the glasshouse, litter increased seedling emergence and growth for surface, but not for buried, seeds. Seeds within the litter layer (no seed-soil contact) showed reduced seedling emergence and growth. In the field, litter did not have a direct effect but emergence was promoted by burial. 4Integrating the effects of microsite quality and seed density showed that litter microsites recruited c. 50% of Bromus pictus seedlings, double that expected from its cover (25%). The positive effect of litter on seed density and on seed longevity outweighed the negative effect of litter acting as a mechanical barrier to burial. 5Inconsistent effects of litter on plant recruitment in arid environments may be due to responses being dependent on seed size and shape, and thus may represent indirect effects acting via the probability of burial. Alternatively, studies may report effects only on seed retention or emergence and growth rather than net effects on establishment. [source] Weak phylogenetic effects on ecological niches of Sylvia warblersJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2003K. Böhning-Gaese Abstract To understand the evolution of ecological niches it is important to know whether niche evolution is constrained by phylogeny. We approached this question for Sylvia warblers by testing if closely related species are more similar in 20 ecologically relevant morphological traits than distantly related species. Phylogenetic relatedness was quantified using a molecular phylogeny based on the mitochondrial cytochrome b gene. By Principal Component Analysis (PCA) two major niche axes were extracted. We tested the individual ecomorphological traits and the positions of the species on the PCA axes for phylogenetic effects using Mantel tests. The results demonstrated small but significant phylogenetic effects only for the length of the middle toe, a trait probably correlated with locomotion. In general, however, phylogenetic effects were very weak. This suggests that ecological niches in passerine birds have the potential to evolve rapidly and are not subject to major phylogenetic constraints. [source] A study of the four-path model for scattering from an object above a half spaceMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2001Joel T. Johnson Abstract A study of scattering from a dielectric object located above a half space is performed to clarify the accuracy of a "four-path" model which includes single scattering effects only. An iterative method-of-moments solution is used for comparison, and both frequency- and time-domain examples are illustrated to clarify the scattering interactions which occur. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 130,134, 2001. [source] Acotiamide (Z-338) as a possible candidate for the treatment of functional dyspepsiaNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2010H. Suzuki Abstract Acotiamide hydrochloride is a novel upper gastrointestinal (GI) motility modulator and stress regulator currently being developed for the treatment of functional dyspepsia (FD). The mechanism underlying the enhancement of GI motility by this agent has been proposed to be based on its muscarinic antagonism and inhibitory effects on acetylcholinesterase activity. Pathophysiological studies showed that acotiamide significantly improved both delayed gastric emptying and feeding inhibition in restraint stress-induced model, but did not affect both normal gastric emptying and feeding in intact animals, indicating that acotiamide exerted effects only on the impaired gastric emptying and feeding behavior. According to the clinical pilot study in Europe, acotiamide, at the dose of 100 mg t.i.d., showed to improve the symptoms and quality of life of patients with FD, indicating the need for larger scale symptomatic studies on the efficacy of acotiamide in patients with FD. The recent phase II studies conducted in Japan presented in this issue of the journal also confirmed that acotiamide, at the optimal dose of 100 mg, has potential therapeutic efficacy, especially for meal-related FD symptoms. Although a phase III study is on going, acotiamide is now expected as a novel treatment option for FD. [source] Acotiamide hydrochloride (Z-338), a novel prokinetic agent, restores delayed gastric emptying and feeding inhibition induced by restraint stress in ratsNEUROGASTROENTEROLOGY & MOTILITY, Issue 9 2008K. Seto Abstract, Acotiamide hydrochloride (Z-338) is a member of new class prokinetic agents currently being developed for the treatment of functional dyspepsia (FD). DNA microarray analysis showed that acotiamide altered the expressions of stress-related genes such as , -aminobutyric acid (GABA) receptors, GABA transporters and neuromedin U (NmU) in the medulla oblongata or hypothalamus after administration of acotiamide. Therefore, effects of acotiamide on stress-related symptoms, delayed gastric emptying and feeding inhibition, in rats were examined. Acotiamide significantly improved both delayed gastric emptying and feeding inhibition in restraint stress-induced model, but did not affect both basal gastric emptying and feeding in intact rats, indicating that acotiamide exerted effects only on gastric emptying and feeding impaired by the stress. On the other hand, mosapride showed significant acceleration of gastric emptying in intact and restraint stress-induced model, and itopride showed no effect on restraint stress-induced delayed gastric emptying. In addition, gene expression of NmU increased by restraint stress was suppressed by administration of acotiamide, while acotiamide had no effect on delayed gastric emptying induced by an intracerebroventricular administration of NmU, suggesting that the suppressive effect of acotiamide on gene expression of NmU might be important to restore delayed gastric emptying or feeding inhibition induced by restraint stress. These findings suggest that acotiamide might play an important role in regulation of stress response. As stress is considered to be a major contributing factor in the development of FD, the observed effects may be relevant for symptom improvement in FD. [source] Characterizing the ERP Old,New effect in a short-term memory taskPSYCHOPHYSIOLOGY, Issue 5 2008Jared F. Danker Abstract The early and late components of the event-related potential (ERP) Old,New effect are well characterized with respect to long-term memory, and have been associated with processes of familiarity and recollection, respectively. Now, using a short-term memory paradigm with verbal and nonverbal stimuli, we explored the way that these two components respond to variation in recency and stimulus type. We found that the amplitude of the early component (or frontal N400, FN400) showed Old,New effects only for verbal stimuli and increased with recency. In contrast, the later component (or late positive component, LPC) showed Old,New effects across a range of stimulus types and did not scale with recency. These results are consistent with the way that these same ERP components have been characterized in long-term memory, supporting the idea that some of the same processes underlie long- and short-term item recognition. [source] Spatiotemporal analysis of experimental differences in event-related potential data with partial least squaresPSYCHOPHYSIOLOGY, Issue 3 2001Nancy J. Lobaugh One challenge in the analysis of event-related potentials (ERPs) is to identify task-related differences in scalp topography. The multivariate Partial Least Squares (PLS) analysis was used to identify the spatiotemporal distribution of ERP differences related to experimental manipulations. Two simulations included latency shifts and amplitude changes at peaks with temporal overlap. PLS identified effects only at modeled timepoints and electrodes. In contrast, principal components analysis identified differences at most timepoints. We also demonstrated that PLS identified combinations of waveform differences, not isolated sources. ERP components in an auditory oddball task were also assessed with PLS. The primary distinction was between ERPs on hit and correct rejection trials, expressed at multiple timepoints and electrodes. PLS provides a mechanism to describe experimental differences in ERP waveforms, simultaneously across the head. [source] Orienting of visual attention among persons with autism spectrum disorders: reading versus responding to symbolic cuesTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 7 2009Oriane Landry Background:, Are persons with autism spectrum disorders (ASD) slower than typically developing individuals to read the meaning of a symbolic cue in a visual orienting paradigm? Methods:, Participants with ASD (n = 18) and performance mental age (PMA) matched typically developing children (n = 16) completed two endogenous orienting conditions in which the cue exposure time and response preparation time were manipulated within a consistent series of cue-target stimulus onset asynchronies (SOAs). Results:, Participants with ASD displayed facilitation effects at all SOAs, whereas typically developing children displayed facilitation effects only at shorter SOAs. The magnitude of the facilitation effect was greater for the group with ASD at 400ms SOA. Both groups showed similar effects of condition, with similar patterns of facilitation in both conditions. Conclusion:, Persons with ASD were not slower to read the symbolic cue, as the effect was elicited by brief cues within longer SOAs before target onset. The participants with ASD were also less efficient in using the predictability of the cues to guide responding. The difficulties of participants with ASD on endogenous orienting occur at the response selection level, not the perceptual level. [source] What Determines the Domestic Bias and Foreign Bias?THE JOURNAL OF FINANCE, Issue 3 2005Evidence from Mutual Fund Equity Allocations Worldwide ABSTRACT We examine how mutual funds from 26 developed and developing countries allocate their investment between domestic and foreign equity markets and what factors determine their asset allocations worldwide. We find robust evidence that these funds, in aggregate, allocate a disproportionately larger fraction of investment to domestic stocks. Results indicate that the stock market development and familiarity variables have significant, but asymmetric, effects on the domestic bias (domestic investors overweighting the local markets) and foreign bias (foreign investors under or overweighting the overseas markets), and that economic development, capital controls, and withholding tax variables have significant effects only on the foreign bias. [source] Genetic parameters for gestation length and the relationship with birth weight and carcass traits in Japanese Black cattleANIMAL SCIENCE JOURNAL, Issue 3 2008Takayuki IBI ABSTRACT The objectives of this study were to estimate genetic parameters for gestation length (GL), including estimation of maternal effects, and to investigate the genetic relationships of GL with birth weight and carcass traits in a Japanese Black cattle population. The original data comprised 34 775 records of animals born from October 1999 to August 2003. Two different models were used to analyze the data for GL. The first model (M1) included direct genetic effect of the calf and maternal genetic effect as random effects. The second model (M2) treated GL as a trait of the dam and included direct genetic effects only. M1 was used in bi-variate analysis. The direct and maternal heritabilities for GL estimated from M1 were 0.53 and 0.14, respectively. This result shows that GL is moderately inherited and can be controlled genetically. The direct × maternal genetic correlation for GL was ,0.73. Direct genetic correlations of GL with carcass traits were close to zero. However, genetic correlation of maternal GL with carcass weight was moderate (0.25). [source] Land use legacies in post-agricultural forests in the Doupovské Mountains, Czech RepublicAPPLIED VEGETATION SCIENCE, Issue 2 2009Martin Kopecký Abstract Questions: Do differences in previous land use cause long-lasting changes in soil chemistry? Is vegetation composition affected by the previous land use after 50 years of secondary succession? Is the effect of previous land use caused by pre-existing differences in environmental conditions or mediated through changes in soil chemistry? How important is the effect of previous land use in relation to other factors? Location: Doupovské Mountains, Czech Republic. Methods: A stratified random sampling design was used to collect 91 vegetation relevés with accompanying soil samples. The effects of previous land use (arable field, meadow, pasture) on soil pH, organic carbon (C), total nitrogen (N), C:N ratio and available phosphorus were tested by an analysis of covariance. A canonical correspondence analysis and variation partitioning procedure were used to reveal relationships among previous land use, environmental factors and species composition. Results: Organic C, total N and C:N ratio were significantly influenced by previous land use, while available phosphorus and soil pH were not. Previous land use explained a significant part of the variation in species composition and its effects only partly overlapped with the effects of soil chemistry and terrain attributes. However, the species composition of post-agricultural forests was mostly determined by environmental factors not modified by previous land use. Conclusions: Forest communities that originate on abandoned agricultural land are primarily determined by natural environmental conditions. Nevertheless, the type of previous land use also modifies the species assemblages of these forests and needs to be considered as an important determinant of their composition. [source] Changes in the nutritional parameters of muscles of the common carp (Cyprinus carpio) and the silver carp (Hypophthalmichthys molitrix) following environmental exposure to cyanobacterial water bloomAQUACULTURE RESEARCH, Issue 2 2009Jan Mares Abstract The present study evaluated the effect of naturally developing cyanobacteria on the composition of muscles of two commercially important freshwater fish species. Fish were exposed to cyanobacterial biomass including Microcystis aeruginosa and Microcystis ichthyoblabe for 4 weeks. Then, they were transferred to dechlorinated potable water without any cyanobacteria for another 4-week period, thus modelling their preparation for consumers. Samples of muscles were collected every week during exposure and subsequent stay in dechlorinated potable water. The cyanobacterial water bloom of 3.9,6 × 105 cells mL,1 (133,383 ,g g,1 of total MC DW) induced statistically significant effects only in the content of fatty acids (P<0.05; P<0.01) in the common carp (Cyprinus carpio), while all studied parameters including the content of dry matter and fat (P<0.01), proteins (P<0.05), fatty acid composition (P<0.05; P<0.01) and some amino acids (P<0.05) were affected in the silver carp (Hypophthalmichthys molitrix). This study has shown that cyanobacteria in the environment of commercially produced fish may decrease the dietetic value of fish muscles. [source] | |||||||||||||||||||