QTL analysis of high thermotolerance with superior and downgraded parental yeast strains reveals new minor QTLs and converges on novel causative alleles involved in RNA processing

Revealing QTLs with a minor effect in complex traits remains difficult. Initial strategies had limited success because of interference by major QTLs and epistasis. New strategies focused on eliminating major QTLs in subsequent mapping experiments. Since genetic analysis of superior segregants from natural diploid strains usually also reveals QTLs linked to the inferior parent, we have extended this strategy for minor QTL identification by eliminating QTLs in both parent strains and repeating the QTL mapping with pooled-segregant whole-genome sequence analysis. We first mapped multiple QTLs responsible for high thermotolerance in a natural yeast strain, MUCL28177, compared to the laboratory strain, BY4742. Using single and bulk reciprocal hemizygosity analysis we identified MKT1 and PRP42 as causative genes in QTLs linked to the superior and inferior parent, respectively. We subsequently downgraded both parents by replacing their superior allele with the inferior allele of the other parent. QTL mapping using pooled-segregant whole-genome sequence analysis with the segregants from the cross of the downgraded parents, revealed several new QTLs. We validated the two most-strongly linked new QTLs by identifying NCS2 and SMD2 as causative genes linked to the superior downgraded parent and we found an allele-specific epistatic interaction between PRP42 and SMD2. Interestingly, the related function of PRP42 and SMD2 suggests an important role for RNA processing in high thermotolerance and underscores the relevance of analyzing minor QTLs. Our results show that identification of minor QTLs involved in complex traits can be successfully accomplished by crossing parent strains that have both been downgraded for a single QTL. This novel approach has the advantage of maintaining all relevant genetic diversity as well as enough phenotypic difference between the parent strains for the trait-of-interest and thus maximizes the chances of successfully identifying additional minor QTLs that are relevant for the phenotypic difference between the original parents

Impact of Pediatric Obesity on Grades in Elementary School

Objective: The current study examines the relationship between obesity and academic performance among second grade students. We hypothesized that students who were overweight or obese would have poorer grades than students who were normal weight. Design: Cross-sectional. Setting: Seven elementary schools from a southeast Texas Independent School District. Participants: The sample was composed of 798 ethnically and racially diverse elementary school children. Students were classified as normal weight, overweight, and obese. Main Outcome Measures: Differences in cumulative grades (math, science, and reading) across weight classifications were examined using sex, race/ethnicity, and school socioeconomic level as covariates. Additionally, all subject areas were analyzed independently. Analysis: Linear mixed models and follow-up pairwise comparisons. Results:The linear mixed model revealed significant differences in grades across weight classifications (p\u3c.05). Conclusions and Implications: This study suggests that weight status is an important marker of scholastic success. Addressing overweight may bolster efforts to improve academic performance

Role of the E2g phonon in the superconductivity of MgB2: a Raman scattering study

Temperature dependent Raman scattering studies in polycrystalline MgB2(10<T<300 K)reveal that the E2g phonon does not experience any self energy renormalization effect across the superconducting critical temperature Tc ~ 40 K. In contrast, most of the current theoretical models rely on the role of the E2g phonon in the electron-phonon coupling mechanism of superconductivity in MgB2. According to these models, a hardening of 12% is expected below Tc at the Gamma point of the Brillouim zone. In the presence of our results, those models must be reviewed. The analysis of the temperature dependence of the E2g phonon frequency yields to a isobaric Gruneisen parameter of -1.2< gama(E2g)< 0.2, smaller than the value of 3.9 obtained from isothermal Raman experiments under pressure. It is suggested that this apparent disagreement can be explained in terms of pressure induced changes of the topology of the Fermi surface. Finally we notice that the phonon linewidth presents the expected two-phonon anharmonic decay as a function of T and no anomalous temperature dependence of the linewidth is observed near Tc.Comment: Published in Solid State Comm. 125, 499 (2003

Effects of sediment disturbance regimes on Spartina seedling establishment: implications for salt marsh creation and restoration

Seedling establishment is an important process relevant for the restoration of salt marsh within the framework of sustainable coastal defense schemes. Recent studies have increasingly highlighted how the short-term (i.e., the day-to-day) sediment dynamics can form major bottlenecks for seedling establishment. Until recently, studies on quantifying the threshold values of such short-term sediment dynamics for marsh seedlings remain rare. As accretion/erosion trends and dynamics may differ greatly under global change, we study the effects of short-term sediment disturbance-regimes on seedling establishment of two globally distributed foundation species: Spartina alterniflora and Spartina anglica. Seedlings with different disturbance-free periods were exposed to a set of different accretion/erosion-regimes in the laboratory. Seedling survival appeared to be much more sensitive to erosion than accretion, seedlings with short disturbance-free periods were more sensitive than seedlings with longer ones, and S. alterniflora was more sensitive than S. anglica. Seedlings were less sensitive to gradual changes in sediment height (accretion/erosion) than to abrupt changes where time for morphological adjustment is lacking. Critical erosion depth (the maximum erosion that seedlings are able to withstand) was shown to mainly depend on sedimentation history. Our results confirm that the establishment of Spartina seedlings requires a flooding disturbance-free “window of opportunity” and that sediment disturbances affect their survival both directly and via morphological adjustment. These results provide fundamental insights into seedling establishment that can be used for designing engineering measures to create suitable conditions and enable marsh creation/restoration for nature goals or as part of coastal defense schemes under global change

Formation of the black-hole binary M33 X-7 via mass-exchange in a tight massive system

M33 X-7 is among the most massive X-Ray binary stellar systems known, hosting a rapidly spinning 15.65 Msun black hole orbiting an underluminous 70 Msun Main Sequence companion in a slightly eccentric 3.45 day orbit. Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-Ray luminosity, star's underluminosity, black hole's spin, and eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report that, if M33 X-7 started as a primary of 85-99 Msun and a secondary of 28-32 Msun, in a 2.8-3.1 day orbit, its observed properties can be consistently explained. In this model, the Main Sequence primary transferred part of its envelope to the secondary and lost the rest in a wind; it ended its life as a ~16 Msun He star with a Fe-Ni core which collapsed to a black hole (with or without an accompanying supernova). The release of binding energy and, possibly, collapse asymmetries "kicked" the nascent black hole into an eccentric orbit. Wind accretion explains the X-Ray luminosity, while the black hole spin can be natal.Comment: Manuscript: 18 pages, 2 tables, 2 figure. Supplementary Information: 34 pages, 6 figures. Advance Online Publication (AOP) on http://www.nature.com/nature on October 20, 2010. To Appear in Nature on November 4, 201

Can Parenting Practices Explain the Differences in Beverage Intake According to Socio-Economic Status

Previous research indicated that preschoolers of lower socioeconomic status (SES) consume less healthy beverages than high SES preschoolers. The purpose of this study is to investigate the mediating role of parenting practices in the relationship between SES and plain water, soft drink and prepacked fruit juice (FJ) consumption in European preschoolers. Parents/caregivers of 3.5 to 5.5 years old (n = 6776) recruited through kindergartens in six European countries within the ToyBox-study completed questionnaires on socio-demographics, parenting practices and a food frequency questionnaire. Availability of sugared beverages and plain water, permissiveness towards sugared beverages and lack of self-efficacy showed a mediating effect on SES-differences in all three beverages. Rewarding with sugared beverages significantly mediated SES-differences for both plain water and prepacked FJ. Encouragement to drink plain water and awareness significantly mediated SES-differences for, respectively, plain water and prepacked FJ consumption. Avoiding negative modelling did not mediate any associations. Overall, lower SES preschoolers were more likely to be confronted with lower levels of favourable and higher levels of unfavourable parenting practices, which may lead to higher sugared beverage and lower plain water consumption. The current study highlights the importance of parenting practices in explaining the relation between SES and both healthy and unhealthy beverage consumptio

Can Parenting Practices Explain the Differences in Beverage Intake According to Socio-Economic Status

Previous research indicated that preschoolers of lower socioeconomic status (SES) consume less healthy beverages than high SES preschoolers. The purpose of this study is to investigate the mediating role of parenting practices in the relationship between SES and plain water, soft drink and prepacked fruit juice (FJ) consumption in European preschoolers. Parents/caregivers of 3.5 to 5.5 years old (n = 6776) recruited through kindergartens in six European countries within the ToyBox-study completed questionnaires on socio-demographics, parenting practices and a food frequency questionnaire. Availability of sugared beverages and plain water, permissiveness towards sugared beverages and lack of self-efficacy showed a mediating effect on SES-differences in all three beverages. Rewarding with sugared beverages significantly mediated SES-differences for both plain water and prepacked FJ. Encouragement to drink plain water and awareness significantly mediated SES-differences for, respectively, plain water and prepacked FJ consumption. Avoiding negative modelling did not mediate any associations. Overall, lower SES preschoolers were more likely to be confronted with lower levels of favourable and higher levels of unfavourable parenting practices, which may lead to higher sugared beverage and lower plain water consumption. The current study highlights the importance of parenting practices in explaining the relation between SES and both healthy and unhealthy beverage consumptio