A pistil-expressed pectin methylesterase confers cross-incompatibility between strains of Zea mays.

A central problem in speciation is the origin and mechanisms of reproductive barriers that block gene flow between sympatric populations. Wind-pollinated plant species that flower in synchrony with one another rely on post-pollination interactions to maintain reproductive isolation. In some locations in Mexico, sympatric populations of domesticated maize and annual teosinte grow in intimate associate and flower synchronously, but rarely produce hybrids. This trait is typically conferred by a single haplotype, Teosinte crossing barrier1-s. Here, we show that the Teosinte crossing barrier1-s haplotype contains a pistil-expressed, potential speciation gene, encoding a pectin methylesterase homolog. The modification of the pollen tube cell wall by the pistil, then, is likely a key mechanism for pollen rejection in Zea and may represent a general mechanism for reproductive isolation in grasses.

Effect of participation in a park-based afterschool program on cardiovascular disease risk among severely obese youth.

OBJECTIVES: The prevalence of severe obesity in youth is rising, despite reports of obesity rates stabilizing overall. While reports on treatment outcomes for youth with severe obesity (bariatric surgery, behavioral and pharmacological treatments) exist, very few community-based programs have reported changes in health outcomes in this population. We assessed changes in cardiovascular health risk profiles among racial/ethnic minority youth with severe obesity who participated in Fit2Play™, a park-based afterschool health promotion program. STUDY DESIGN: A longitudinal cohort study. METHODS: Children aged 6-14 years (N = 1546, 51% Hispanic, 44% non-Hispanic black) who participated in the Fit2Play™ in one of 34 urban park sites for one school year over five separate school years (2010-2015) had height, weight, four-site skinfold thicknesses, systolic blood pressure (SBP)/diastolic blood pressure (DBP), fitness tests, and a health/wellness knowledge test collected at the beginning and end of the school year. Two-level repeated measures mixed models examined changes in cardiovascular health outcomes (body mass index [BMI], skinfold thickness, systolic/diastolic blood pressure percentile [SBPP/DBPP], cardiorespiratory fitness [PACER]) in youth with severe obesity over 1- and 2-year follow-up. RESULTS: Compared with baseline, BMI decreased 13% (incidence rate ratio [IRR] 95% confidence interval [CI]: 0.83-0.90), sumof skinfold thicknesses decreased 5% (IRR 95% CI: 0.91-0.99), SBPP decreased 5% (IRR 95% CI: 0.90-0.99), DBPP decreased 19% (IRR 95% CI: 0.77-0.86), and PACER scores increased 12% (IRR 95% CI: 1.0-1.27) after two years of participation in the Fit2Play™ program. CONCLUSIONS: Findings here support community/park-based youth programs as effective and accessible treatment options for reducing cardiovascular disease risk among youth with severe obesity.

Molecular dynamics computations of brine-CO2 interfacial tensions and brine-CO2-quartz contact angles and their effects on structural and residual trapping mechanisms in carbon geo-sequestration.

In the context of carbon geo-sequestration projects, brine-CO(2) interfacial tension γ and brine-CO(2)-rock surface water contact angles θ directly impact structural and residual trapping capacities. While γ is fairly well understood there is still large uncertainty associated with θ. We present here an investigation of γ and θ using a molecular approach based on molecular dynamics computer simulations. We consider a system consisting of CO(2)/water/NaCl and an α-quartz surface, covering a brine salinity range between 0 and 4 molal. The simulation models accurately reproduce the dependence of γ on pressure below the CO(2) saturation pressure at 300 K, and over predict γ by ~20% at higher pressures. In addition, in agreement with experimental observations, the simulations predict that γ increases slightly with temperature or salinity. We also demonstrate that for non-hydroxylated quartz surfaces, θ strongly increases with pressure at subcritical and supercritical conditions. An increase in temperature significantly reduces the contact angle, especially at low-intermediate pressures (1-10 MPa), this effect is mitigated at higher pressures, 20 MPa. We also found that θ only weakly depends on salinity for the systems investigated in this work.

Prevalence of intestinal parasites in rural Southern Indians.

OBJECTIVE: To determine the prevalence of intestinal protozoal and helminthic infection in a rural population. METHOD: Seventy-eight members of 15 families from a village were studied. Stool samples from all subjects were examined on alternate days for one month. RESULTS: The overall prevalence rate of various parasitic infections was 97.4%, with only 2 of 78 subjects not excreting parasites in any of their 15 samples. Eighteen (23.1%) persons had only one type of parasite, while 58 (74.3%) excreted multiple parasites. Giardia and Cryptosporidium were the commonest protozoan infections, affecting 42/78 (53.8%) and 31/78 (39.7%), respectively. Hookworm infestations were the commonest helminthic infections, seen in 48/78 (61.5%). Based on excretion patterns, the asymptomatic individuals could be divided into 2 groups of infrequent and frequent excretors, indicating that the host response may determine the level of parasite replication in the gut.