604 research outputs found
Circadian control of isoprene emissions from oil palm (Elaeis guineensis)
No full textThe emission of isoprene from the biosphere to the atmosphere has a profound effect on the Earth's atmospheric system. Until now, it has been assumed that the primary short-term controls on isoprene emission are photosynthetically active radiation and temperature. Here we show that isoprene emissions from a tropical tree (oil palm, Elaeis guineensis) are under strong circadian control, and that the circadian clock is potentially able to gate light-induced isoprene emissions. These rhythms are robustly temperature compensated with isoprene emissions still under circadian control at 38 degrees C. This is well beyond the acknowledged temperature range of all previously described circadian phenomena in plants. Furthermore, rhythmic expression of LHY/CCA1, a genetic component of the central clock in Arabidopsis thaliana, is still maintained at these elevated temperatures in oil palm. Maintenance of the CCA1/LHY-TOC1 molecular oscillator at these temperatures in oil palm allows for the possibility that this system is involved in the control of isoprene emission rhythms. This study contradicts the accepted theory that isoprene emissions are primarily light-induced
An L(^2) representation of the continuum in heavy particle collisions
No full textThis thesis is concerned with the use of L(^2) or square integrable functions as a representation of the electronic continua in ion-atom collisions. An exact representation of the continuum states is considered for comparison. The functions are optimised in an attempt to remove some of the arbitrary features present in such calculations. The original work of this thesis is mainly concerned with the calculation of single electron processes in collisions between He(^2+)ions and neutral lithium atoms. The cross sections for single electron capture were calculated in a close-coupled approximation, using the semi-classical impact parameter method. A maximum of thirty-two atomic orbitals with plane-wave translational factors attached were centred upon the target and projectile. Satisfactory agreement with experimental data is obtained over the He(^2+)laboratory energy range from 8 to 2000 keV. The results show the importance of the continuum over a restricted range of impact energies. The rest of the research is concerned with direct excitation and ionisation in the same collision system and results are given for He"^' laboratory energies between 20 and 6000 keV. The calculations used a similar close-coupled approximation with up to sixty-five basis states. The best ionisation cross sections reproduce the experimental data apart from a normalization factor. The excitation results were more sensitive to basis set choice. The ionisation cross sections were also investigated using an exact representation of the continuum states, using the First Born Approximation and a t-matrix approximation in an attempt to improve upon the results. The relationship between the present calculations and some previous methods are discussed and suggestions for future work are made. These are the first close-coupled estimates of ionisation for this sytem and show that contributions from target d- and f- states dominate the ionisation cross section around its maximum
Genetic covariation between the author recognition test and reading and verbal abilities: What can we learn from the analysis of high performance?
No full textThe Author Recognition Test (ART) measures print exposure and is a unique predictor of phonological and orthographic processes in reading. In a sample of adolescent and young adult twins and siblings (216 MZ/430 DZ pairs, 307 singletons; aged 11-29 years) ART scores were moderately heritable (67%) and correlated with reading and verbal abilities, with genes largely accounting for the covariance. We also examine whether high (and low) (i.e. 1SD above the mean) represents a quantitative extreme of the normal distribution. Heritability for high ART was of similar magnitude to the full sample, but, a specific genetic factor, independent from both low ART performance and high reading ability, accounted for 53-58% of the variance. This suggests a distinct genetic etiology for high ART ability and we speculate that the specific genetic influence is on orthographical processing, a critical factor in developing word recognition skills
Genetic influences on handedness: Data from 25,732 Australian and Dutch twin families
No full textHandedness refers to a consistent asymmetry in skill or preferential use between the hands and is related to lateralization within the brain of other functions such as language. Previous twin studies of handedness have yielded inconsistent results resulting from a general lack of statistical power to find significant effects. Here we present analyses from a large international collaborative study of handedness (assessed by writing/drawing or self report) in Australian and Dutch twins and their siblings (54,270 individuals from 25,732 families). Maximum likelihood analyses incorporating the effects of known covariates (sex, year of birth and birth weight) revealed no evidence of hormonal transfer, mirror imaging or twin specific effects. There were also no differences in prevalence between zygosity groups or between twins and their singleton siblings. Consistent with previous meta-analyses, additive genetic effects accounted for about a quarter (23.64%) of the variance (95%CI 20.17, 27.09%) with the remainder accounted for by non-shared environmental influences. The implications of these findings for handedness both as a primary phenotype and as a covariate in linkage and association analyses are discussed.Sarah E. Medland, David L. Duffy, Margaret J. Wright, Gina M. Geffen, David A. Hay, Florence Levy, Catherina E.M. van-Beijsterveldt, Gonneke Willemsen, Grant C. Townsend, Vicki White, Alex W. Hewitt, David A. Mackey, J. Michael Bailey, Wendy S. Slutske, Dale R. Nyholt, Susan A. Treloar, Nicholas G. Martin, Dorret I. Booms
Genetic covariation among facets of openness to experience and general cognitive ability
No full textGenetic and environmental sources of covariation among cognitive measures of verbal IQ, performance IQ (PIQ), academic achievement, 2-choice reaction time (CRT), inspection time (IT) and the 6 Openness facets of the NEO Personality Inventory-Revised (NEO PI-R) were examined. The number of twin and twin–sibling pairs ranged from 432 (182 MZ, 350 DZ/sibling) to 1023 (273 MZ, 750 DZ/sibling) for cognitive measures, and between 432 (90 MZ, 342 DZ/sibling) — 437 (91 MZ, 346 DZ/sibling) for Openness facets. Structural equation modeling best supported a model with a 3-factor additive genetic structure. A genetic general factor subsumed the 5 cognitive measures and 5 of the 6 Openness facets (Actions did not load significantly). A second additive genetic factor incorporated the 6 Openness facets, and a third additive genetic factor incorporated the 5 cognitive measures. Specific additive and dominance genetic effects were also evident, as were shared common and shared unique environmental influences, and specific unique environmental effects. The Openness facets of Ideas and Values evidenced the strongest phenotypic correlations with cognitive indices, particularly verbal measures. The genetic correlations among Openness facets and cognitive measures ranged from −.06 to .79. Results were interpreted as suggesting that Openness is related to general cognitive ability (g) through a genetic mechanism and that gengenders a minor but discernable disposition towards Openness for the majority of facets
Reviews: French Studies
No full textDavid DRAKE. 2005. French Intellectuals and Politics from the Dreyfus Affair to the Occupation. New York: Palgrave/MacMillan. 214 pp. £ 45, ISBN 0-333-77812-X.Alan SINGERMAN. 2004. Apprentissage du cinéma françaisLivre de l’étudiant. Newburyport, MA: Focus Publishing. 388 pp.ISBN 9-781585-101047.Brian MORTON and Donald C. SPINELLI. 2003. Beaumarchaisand the American Revolution. Lanham, MD: Lexington Books.ISBN 0-7391-0468-3. 363pp. 84.Nicholas HEWITT. 2003. The Cambridge Companion to Modern French Culture. Cambridge, UK: Cambridge University Press. Hardback ISBN 0-521-79123-5. 353pp. 65. Paperback ISBN 0-521-79465-X. 353pp. $23
Oceanic Sources of Sulphur and their Contribution to the Atmospheric Sulphur Budget: A Review
No full textDo Dimethyl Sulphide Emissions from the North Atlantic Contribute to Rainwater Acidity and the Atmospheric Sulphur Burden in the UK?
No full textInvestigating the potential role of genetic and epigenetic variation of DNA methyltransferase genes in hyperplastic polyposis syndrome
No full textData source: Supporting information, https://doi.org/10.1371/journal.pone.0016831.s001BACKGROUND: Hyperplastic Polyposis Syndrome (HPS) is a condition associated with multiple serrated polyps, and an increased risk of colorectal cancer (CRC). At least half of CRCs arising in HPS show a CpG island methylator phenotype (CIMP), potentially linked to aberrant DNA methyltransferase (DNMT) activity. CIMP is associated with methylation of tumor suppressor genes including regulators of DNA mismatch repair (such as MLH1, MGMT), and negative regulators of Wnt signaling (such as WIF1). In this study, we investigated the potential for interaction of genetic and epigenetic variation in DNMT genes, in the aetiology of HPS. METHODS: We utilized high resolution melting (HRM) analysis to screen 45 cases with HPS for novel sequence variants in DNMT1, DNMT3A, DNMT3B, and DNMT3L. 21 polyps from 13 patients were screened for BRAF and KRAS mutations, with assessment of promoter methylation in the DNMT1, DNMT3A, DNMT3B, DNMT3L MLH1, MGMT, and WIF1 gene promoters. RESULTS: No pathologic germline mutations were observed in any DNA-methyltransferase gene. However, the T allele of rs62106244 (intron 10 of DNMT1 gene) was over-represented in cases with HPS (p<0.01) compared with population controls. The DNMT1, DNMT3A and DNMT3B promoters were unmethylated in all instances. Interestingly, the DNMT3L promoter showed low levels of methylation in polyps and normal colonic mucosa relative to matched disease free cells with methylation level negatively correlated to expression level in normal colonic tissue. DNMT3L promoter hypomethylation was more often found in polyps harbouring KRAS mutations (p = 0.0053). BRAF mutations were common (11 out of 21 polyps), whilst KRAS mutations were identified in 4 of 21 polyps. CONCLUSIONS: Genetic or epigenetic alterations in DNMT genes do not appear to be associated with HPS, but further investigation of genetic variation at rs62106244 is justified given the high frequency of the minor allele in this case series.Musa Drini, Nicholas C. Wong, Hamish S. Scott, Jeffrey M. Craig, Alexander Dobrovic, Chelsee A. Hewitt, Christofer Dow, Joanne P. Young, Mark A. Jenkins, Richard Saffery and Finlay A. Macra
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