Alkaline Hydrolyzable-Nitrogen, Seeding Date, and Clay-Fixed Ammonium as Potential Indicators of Rice Response to Nitrogen Fertilization in Arkansas

Several potential indicators of rice (Oryza sativa L.) response to nitrogen (N) fertilization include the soil\u3c&rsquos\u3es alkaline hydrolyzable\u3c&minus\u3eN (AH\u3c&minus\u3eN) concentration, seeding date, and the soil\u3c&rsquos\u3es clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN content. Three studies were conducted to: (1) correlate AH\u3c&minus\u3eN, determined using Illinois Soil Nitrogen Test (ISNT) or Nitrogen Soil Test for Rice (N\u3c&minus\u3eSTaR), to plant parameters of interest and develop a fertilizer N rate calibration curve capable of predicting the 95% relative grain yield (RGY) fertilizer N rate for rice grown on clayey soils; (2) evaluate the influence of seeding date and N fertilization on rice plant growth and grain yield; and (3) evaluate the plant\u3c&minus\u3eavailable portion of clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN using N\u3c&minus\u3eSTaR and quantify total clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN using dry combustion. Alkaline hydrolyzable\u3c&minus\u3eN, quantified using ISNT or N\u3c&minus\u3eSTaR in the first study, explained 83% of the variability in calibration based on a 0 to 30\u3c&minus\u3ecm sampling depth. The second study revealed that grain yield exhibited a tendency to be greater for rice seeded in April or May compared to June seeding dates in Arkansas. Results of the third study indicated a low percentage (4\u3c&ndash\u3e6%) of total clay fixed NH4\u3c&ndash\u3eN was predicted to be plant\u3c&minus\u3eavailable NH4\u3c&ndash\u3eN based on N\u3c&minus\u3eSTaR. Fertilizer N rate recommendations based on the ISNT or N\u3c&minus\u3eSTaR soil test methods evaluated in the first study revealed the potential of soil\u3c&minus\u3ebased tests to improve economic, agronomic, and environmental aspects of rice produced on clayey soils. Seeding date selection can influence rice grain yield which may in turn influence fertilizer N management. However, the fertilizer N rate required to maximize grain yield when seeding date was delayed remained unclear following completion of the second study and continued research is required to identify the influence of seeding date on the yield\u3c&minus\u3emaximizing, fertilizer N rate for rice grown in Arkansas. The recovery of clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN by N\u3c&minus\u3eSTaR indicated a portion of total clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN was expected to be available for plant uptake. However, additional research is required to verify the low recovery of clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN and the influence of clay\u3c&minus\u3efixed NH4\u3c&ndash\u3eN on the quantity of AH\u3c&minus\u3eN determined by N\u3c&minus\u3eSTaR

Continued Decline of Malaria in The Gambia with Implications for Elimination

BACKGROUND: A substantial decline in malaria was reported to have occurred over several years until 2007 in the western part of The Gambia, encouraging consideration of future elimination in this previously highly endemic region. Scale up of interventions has since increased with support from the Global Fund and other donors. METHODOLOGY/PRINCIPAL FINDINGS: We continued to examine laboratory records at four health facilities previously studied and investigated six additional facilities for a 7 year period, adding data from 243,707 slide examinations, to determine trends throughout the country until the end of 2009. We actively detected infections in a community cohort of 800 children living in rural villages throughout the 2008 malaria season, and assayed serological changes in another rural population between 2006 and 2009. Proportions of malaria positive slides declined significantly at all of the 10 health facilities between 2003 (annual mean across all sites, 38.7%) and 2009 (annual mean, 7.9%). Statistical modelling of trends confirmed significant seasonality and decline over time at each facility. Slide positivity was lowest in 2009 at all sites, except two where lowest levels were observed in 2006. Mapping households of cases presenting at the latter sites in 2007-2009 indicated that these were not restricted to a few residual foci. Only 2.8% (22/800) of a rural cohort of children had a malaria episode in the 2008 season, and there was substantial serological decline between 2006 and 2009 in a separate rural area. CONCLUSIONS: Malaria has continued to decline in The Gambia, as indicated by a downward trend in slide positivity at health facilities, and unprecedented low incidence and seroprevalence in community surveys. We recommend intensification of control interventions for several years to further reduce incidence, prior to considering an elimination programme

New loci associated with birth weight identify genetic links between intrauterine growth and adult height and metabolism.

Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood. Previous genome-wide association studies of birth weight identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes and a second variant, near CCNL1, with no obvious link to adult traits. In an expanded genome-wide association meta-analysis and follow-up study of birth weight (of up to 69,308 individuals of European descent from 43 studies), we have now extended the number of loci associated at genome-wide significance to 7, accounting for a similar proportion of variance as maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes, ADRB1 with adult blood pressure and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism

Independent genomewide screens identify the tumor suppressor VTRNA2-1 as a human epiallele responsive to periconceptional environment

Background: Interindividual epigenetic variation that occurs systemically must be established prior to gastrulation in the very early embryo and, because it is systemic, can be assessed in easily biopsiable tissues. We employ two independent genome-wide approaches to search for such variants. Results: First, we screen for metastable epialleles by performing genomewide bisulfite sequencing in peripheral blood lymphocyte (PBL) and hair follicle DNA from two Caucasian adults. Second, we conduct a genomewide screen for genomic regions at which PBL DNA methylation is affected by season of conception in rural Gambia. Remarkably, both approaches identify the genomically imprinted VTRNA2-1 as a top environmentally responsive epiallele. We demonstrate systemic and stochastic interindividual variation in DNA methylation at the VTRNA2-1 differentially methylated region in healthy Caucasian and Asian adults and show, in rural Gambians, that periconceptional environment affects offspring VTRNA2-1 epigenotype, which is stable over at least 10 years. This unbiased screen also identifies over 100 additional candidate metastable epialleles, and shows that these are associated with cis genomic features including transposable elements. Conclusions: The non-coding VTRNA2-1 transcript (also called nc886) is a putative tumor suppressor and modulator of innate immunity. Thus, these data indicating environmentally induced loss of imprinting at VTRNA2-1 constitute a plausible causal pathway linking early embryonic environment, epigenetic alteration, and human disease. More broadly, the list of candidate metastable epialleles provides a resource for future studies of epigenetic variation and human disease

Effect of Organic Amendments on Phosphorus Fractionation in a Lead-Contaminated Urban Soil

Effect of Organic Amendments on Phosphorus Fractionation in a Lead-Contaminated Urban Soil Abstract: A sequential phosphorus extraction scheme was applied to a lead-(Pb) contaminated soil in Herculaneum, MO for both a field and incubation study. The objectives of this project were; (1) lower soil P fixation and retention through the addition of organically amended P sources; (2) identify the distribution of P among five operationally defined pools of extractable phosphate following treatment incorporation; (3) determine portion of labile P derived from vermicompost (VC); and (4) identify treatments that could potentially lower bioaccessible Pb over an eight-week period. Sequential fractionation identified the Aluminum-associated P (Al-P) fraction as the fraction responding the most to treatment addition. Retention as Al-P could be effectively reduced using the organic amendments evaluated in this study in combination with VC. Amended triple super phosphate (TSP) and VC lowered bioaccessible Pb concentration compared to a non-amended plot. This finding may provide some experimental justification for the application of VC in combination with TSP to Pb-contaminated soil. Further research focusing on a combination of these P sources applied to Pb-contaminated soil could elucidate the conclusion postulated by this research

The effect of the lipid layer on tear film deposition and thinning

This work mathematically models the effects of surfactants during tear film deposition and subsequent thinning. The surfactants occur naturally on the surface of the tear film in the form of a lipid layer. A lubrication model is developed that describes lipid spreading and the evolution of the tear film height during and after an opening blink. Numerical methods are applied to the model, which includes the effects of lipid concentration, surface tension, viscosity, evaporation and gravity. It is found that the lipid layer continues to spread upwards on the cornea after the opening blink, in agreement with experimental work. It is also shown that lipids play an important role in drawing the tear film up the cornea during the opening blink. Further non-uniform distributions of lipids may lead to a rapid thinning of the tear film behind the advancing lipid front, resulting in the formation of surface capillary waves or shocks. Preliminary tear-scope and fluorescein experiments were undertaken to visualise the motion of the lipid layer and any associated shocks immediately after a blink. Using the experimental data, lipid particles were tracked to determine the surface velocity and these results were compared to the model predictions

Exploring the High-Pressure Phases of Carbon through X-ray Diffraction of Dynamic Compression Experiments on Sandia’s Z Pulsed Power Facility

The carbon phase diagram is rich with polymorphs which possess very different physical and optical properties ideal for different scientific and engineering applications. An understanding of the dynamically driven phase transitions in carbon is particularly important for applications in inertial confinement fusion, as well as planetary and meteorite impact histories. Experiments on the Z Pulsed Power Facility at Sandia National Laboratories generate dynamically compressed high-pressure states of matter with exceptional uniformity, duration, and size that are ideal for investigations of fundamental material properties. X-ray diffraction (XRD) is an important material physics measurement because it enables direct observation of the strain and compression of the crystal lattice, and it enables the detection and identification of phase transitions. Several unique challenges of dynamic compression experiments on Z prevent using XRD systems typically utilized at other dynamic compression facilities, so novel XRD diagnostics have been designed and implemented. We performed experiments on Z to shock compress carbon (pyrolytic graphite) samples to pressures of 150–320 GPa. The Z-Beamlet Laser generated Mn-Heα (6.2 keV) X-rays to probe the shock-compressed carbon sample, and the new XRD diagnostics measured changes in the diffraction pattern as the carbon transformed into its high-pressure phases. Quantitative analysis of the dynamic XRD patterns in combination with continuum velocimetry information constrained the stability fields and melting of high-pressure carbon polymorphs