627 research outputs found
Odour and colour polymorphism in the food-deceptive orchid Dactylorhiza romana
The food deceptive orchid, Dactylorhiza romana (Sebastiani) Soó exhibits a colour polymorphism with yellow, red, and intermediate orange morphs. In this study we tested if floral odour differed among the three distinct colour morphs. We identified 23 odour compounds in D. romana, and all of them occurred in the three colour morphs. Monoterpenes dominated the floral scent. On the basis of Euclidean distances of relative amounts of compounds, yellow morphs were closer to each other than to orange or red morphs. Differentiation of the morphs was mainly due to linalool and benzaldehyde. Linalool occurred in low relative amounts in the yellow morphs, but in high amounts in some of the red individuals, whereas benzaldehyde occurred in higher relative amounts in yellow morphs. Linalool and benzaldehyde are known to be important signal-substances in plant-insect communication, however, it remains to be shown whether insects can discriminate between flower morphs on the basis of the here shown odour difference
Brief report: quality of life is impaired in pediatric burn survivors with posttraumatic stress disorder
OBJECTIVE: This study assessed health-related quality of life (HRQOL) and posttraumatic stress disorder (PTSD) in pediatric burn survivors and examined associations between PTSD and HRQOL. METHODS: Forty-three burn survivors, ages 7-16 years, were interviewed at an average of 4.4 years after their accident using the Clinician-Administered PTSD Scale for Children and Adolescents and the TNO-AZL Child Quality of Life Questionnaire. RESULTS: Eight children (18.6%) met DSM-IV criteria for current PTSD. While most dimensions of HRQOL were within normal limits, social functioning was impaired. Severity of PTSD was significantly associated with physical, cognitive, and emotional dimensions of HRQOL. Children with PTSD reported an impaired overall HRQOL and limited physical (e.g., more bodily complaints) and emotional functioning (e.g., more feelings of sadness). CONCLUSIONS: This study provides tentative evidence for a considerably high prevalence of PTSD in pediatric burn survivors and for a negative association between PTSD and HRQO
Posttraumatic stress and behavior problems in infants and toddlers with burns
This study assessed posttraumatic stress disorder (PTSD) and behavior problems in young children with burns and examined individual, injury-related, and family-related determinants. Seventy-six children, aged 12-49 months, were assessed at an average of 15 months after their burn injury, using parents as informants on the posttraumatic stress disorder semi-structured interview and observational record for infants and young children and the child behavior checklist. Ten children (13.2%) met the alternative criteria for PTSD proposed by Scheeringa et al. Number of PTSD symptoms were associated with family-related variables (maternal PTSD, quality of family relations). Compared to community norms, children with burns showed less externalizing behavior problems, and internalizing behavior problems were within the normal range. Overall, behavioral adjustment was associated with the quality of family relations (cohesion, expressiveness, conflicts). Whereas behavior was found to be normal in young children with burns, this study provides evidence for a substantial prevalence of PTS
Variability in Floral Scent in Rewarding and Deceptive Orchids: The Signature of Pollinator-imposed Selection?
Background and Aims A comparative investigation was made of floral scent variation in the closely related, food-rewarding Anacamptis coriophora and the food-deceptive Anacamptis morio in order to identify patterns of variability of odour compounds in the two species and their role in pollinator attraction/avoidance learning. Methods Scent was collected from plants in natural populations and samples were analysed via quantitative gas chromatography and mass spectrometry. Combined gas chromatography and electroantennographic detection was used to identify compounds that are detected by the pollinators. Experimental reduction of scent variability was performed in the field with plots of A. morio plants supplemented with a uniform amount of anisaldehyde. Key Results Both orchid species emitted complex odour bouquets. In A. coriophora the two main benzenoid compounds, hydroquinone dimethyl ether (1,4-dimethoxybenzene) and anisaldehyde (methoxybenzaldehyde), triggered electrophysiological responses in olfactory neurons of honey-bee and bumble-bee workers. The scent of A. morio, however, was too weak to elicit any electrophysiological responses. The overall variation in scent was significantly lower in the rewarding A. coriophora than in the deceptive A. morio, suggesting pollinator avoidance-learning selecting for high variation in the deceptive species. A. morio flowers supplemented with non-variable scent in plot experiments, however, did not show significantly reduced pollination success. Conclusions Whereas in the rewarding A. coriophora stabilizing selection imposed by floral constancy of the pollinators may reduce scent variability, in the deceptive A. morio the emitted scent seems to be too weak to be detected by pollinators and thus its high variability may result from relaxed selection on this floral trai
Biomarkers of aging associated with past treatments in breast cancer survivors.
Radiation and chemotherapy are effective treatments for cancer, but are also toxic to healthy cells. Little is known about whether prior exposure to these treatments is related to markers of cellular aging years later in breast cancer survivors. We examined whether past exposure to chemotherapy and/or radiation treatment was associated with DNA damage, telomerase activity, and telomere length 3-6 years after completion of primary treatments in breast cancer survivors (stage 0-IIIA breast cancer at diagnosis). We also examined the relationship of these cellular aging markers with plasma levels of Interleukin (IL)-6, soluble TNF-receptor-II (sTNF-RII), and C-reactive protein (CRP). Ninety-four women (36.4-69.5 years; 80% white) were evaluated. Analyses adjusting for age, race, BMI, and years from last treatment found that women who had prior exposure to chemotherapy and/or radiation compared to women who had previously received surgery alone were more likely to have higher levels of DNA damage (P = .02) and lower telomerase activity (P = .02), but did not have differences in telomere length. More DNA damage and lower telomerase were each associated with higher levels of sTNF-RII (P's < .05). We found that exposure to chemotherapy and/or radiation 3-6 years prior was associated with markers of cellular aging, including higher DNA damage and lower telomerase activity, in post-treatment breast cancer survivors. Furthermore, these measures were associated with elevated inflammatory activation, as indexed by sTNF-RII. Given that these differences were observed many years after the treatment, the findings suggest a long lasting effect of chemotherapy and/or radiation exposure
Hyperbolic odorant mixtures as a basis for more efficient signaling between flowering plants and bees
Animals use odors in many natural contexts, for example, for finding mates or food, or signaling danger. Most analyses of natural odors search for either the most meaningful components of a natural odor mixture, or they use linear metrics to analyze the mixture compositions. However, we have recently shown that the physical space for complex mixtures is ‘hyperbolic’, meaning that there are certain combinations of variables that have a disproportionately large impact on perception and that these variables have specific interpretations in terms of metabolic processes taking place inside the flower and fruit that produce the odors. Here we show that the statistics of odorants and odorant mixtures produced by inflorescences (Brassica rapa) are also better described with a hyperbolic rather than a linear metric, and that combinations of odorants in the hyperbolic space are better predictors of the nectar and pollen resources sought by bee pollinators than the standard Euclidian combinations. We also show that honey bee and bumble bee antennae can detect most components of the B. rapa odor space that we tested, and the strength of responses correlates with positions of odorants in the hyperbolic space. In sum, a hyperbolic representation can be used to guide investigation of how information is represented at different levels of processing in the CNS
RAPID COMMUNICATION FLORAL ODOR VARIATION IN TWO HETEROSTYLOUS SPECIES OF Primula
Abstract-Floral traits such as odor, color, and morphology are important pollinator attractants. Variation in floral traits may influence floral constancy, the tendency of pollinating insects to visit flowers of only one type. We investigated for the first time variation in odor between floral morphs in heterostylous species. We analyzed inter-and intraspecific odor variation in the Bpin^and Bthrum^floral morphs of sympatric Primula elatior and P. farinosa (Primulaceae). Floral volatiles were sampled with headspace sorption. Quantitative analysis and chemical identification were performed by gas chromatography coupled to mass spectrometry. The species produced different floral bouquets. P. elatior emitted mostly limonene with small amounts of a-pinene, myrcene, and sabinene. P. farinosa produced benzaldehyde, 4-oxoisophorone (2,6,6-trimethyl-2-cyclohexene-1,4-dione), benzyl alcohol, and benzyl acetate. These interspecific differences may play a role in promoting floral constancy and maintaining species integrity. Conversely, no differences were detected between the scents of pin and thrum morphs within each species. Heterostyly relies on pollinators visiting both floral morphs. There may be stabilizing selection against divergences in traits that may cause pollinators to develop floral constancy to only one of the floral morphs
Heavy Quarkonium and nonperturbative corrections
We analyse the possible existence of non-perturbative contributions in heavy
systems ( and need not have the same flavour) which
cannot be expressed in terms of local condensates. Starting from QCD, with well
defined approximations and splitting properly the fields into large and small
momentum components, we derive an effective lagrangian where hard gluons (in
the non-relativistic aproximation) have been integrated out. The large momentum
contributions (which are dominant) are calculated using Coulomb type states.
Besides the usual condensate corrections, we see the possibility of new
non-perturbative contributions. We parametrize them in terms of two low
momentum correlators with Coulomb bound state energy insertions . We
realize that the Heavy Quark Effective lagrangian can be used in these
correlators.
We calculate the corrections that they give rise to in the decay constant,
the bound state energy and the matrix elements of bilinear currents at zero
recoil. We study the cut-off dependence of the new contributions and we see
that it matches perfectly with that of the large momentum contributions.
We consider two situations in detail: i) () and ii) , and briefly discuss the
expected size of the new contributions in , and
systems.Comment: 28 pages, LaTeX. Minor changes, some comments and numerical results
added. To be published in Phys. Rev.
Increased retention of functional fusions to toxic genes in new two-hybrid libraries of the E. coli strain MG1655 and B. subtilis strain 168 genomes, prepared without passaging through E. coli
BACKGROUND: Cloning of genes in expression libraries, such as the yeast two-hybrid system (Y2H), is based on the assumption that the loss of target genes is minimal, or at worst, managable. However, the expression of genes or gene fragments that are capable of interacting with E. coli or yeast gene products in these systems has been shown to be growth inhibitory, and therefore these clones are underrepresented (or completely lost) in the amplified library. RESULTS: Analysis of candidate genes as Y2H fusion constructs has shown that, while stable in E. coli and yeast for genetic studies, they are rapidly lost in growth conditions for genomic libraries. This includes the rapid loss of a fragment of the E. coli cell division gene ftsZ which encodes the binding site for ZipA and FtsA. Expression of this clone causes slower growth in E. coli. This clone is also rapidly lost in yeast, when expressed from a GAL1 promoter, relative to a vector control, but is stable when the promoter is repressed. We have demonstrated in this report that the construction of libraries for the E. coli and B. subtilis genomes without passaging through E. coli is practical, but the number of transformants is less than for libraries cloned using E. coli as a host. Analysis of several clones in the libraries that are strongly growth inhibitory in E. coli include genes for many essential cellular processes, such as transcription, translation, cell division, and transport. CONCLUSION: Expression of Y2H clones capable of interacting with E. coli and yeast targets are rapidly lost, causing a loss of complexity. The strategy for preparing Y2H libraries described here allows the retention of genes that are toxic when inappropriately expressed in E. coli, or yeast, including many genes that represent potential antibacterial targets. While these methods are generally applicable to the generation of Y2H libraries from any source, including mammalian and plant genomes, the potential of functional clones interacting with host proteins to inhibit growth would make this approach most relevant for the study of prokaryotic genomes
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