DEVELOPING A NOVEL HYPOMETHYLATED POPULATION AND CHARACTERIZING A STABLE EARLY FLOWERING EPIMUTANT IN STRAWBERRY (FRAGARIA VESCA)

DNA methylation, as one of the epigenetic marks, can be passed from generation to generation. Epigenetic regulation of phenotypic traits can be demonstrated by altering methylation patterns with DNA demethylating reagent 5-azacytidine (5-azaC). Woodland strawberry (Fragaria vesca, 2n=2x=14) has a rapid generation time (3.5 months in the greenhouse), small plant stature and small sequenced genome size (~240 MB). F. vesca makes an ideal model system for genomics analysis and gene functional study in the Rosaceae family. In order to obtain a F. vesca population with the same genetic background but increased variation for epigenetic information, 5-azaC was used to generate a hypomethylated population by treating highly inbred seeds from Hawaii 4 (H4S8). The uniform genetic background was first confirmed using Amplified Fragment Length Polymorphism (AFLP). Additionally, whole genome sequencing demonstrated the epimutagenic, not mutagenic, effect of 5-azaC resulting in primary DNA sequence changes. Subsequent detailed phenotypic assessments measured flowering time, rosette diameter and stolon emergence time. Expanded variation in these phenotypic traits was observed in the hypomethylated population. Distinct DNA methylation patterns were detected using Methylation Sensitive Amplification Polymorphism (MSAP) in early flowering, late flowering, and small rosette diameter lines. The inheritance of methylation profiles were confirmed by bisulfite sequencing of targeted regions. The inheritance study following early flowering, late flowering, and late stolon emergence time variants through meiosis were demonstrated. It revealed early flowering was stably inherited for at least five meiotic generations but the late flowering phenotype reverted back to the control after two generations. Furthermore, the clonal transmission of the early flowering trait to daughter plants was also confirmed through mitosis. Characterization of the fifth generation (H4S13) early flowering lines was performed using high-resolution methylation combined with RNA-Seq. Differentially expressed genes involved in the flowering time pathway were detected, especially those involved in the photoperiod pathway. The up-regulation of downstream genes in flowering pathway NUCLEAR FACTOR Y, SUBUNIT B2 (NFYB2), FLOWERING LOCUS T (FT, the highest fold change), FRUITFULL (FUL) and SEPALLATA3 (SEP3) likely contributed to the floral transition. Significantly different CG methylation levels of the FT gene and coding sequence regions were observed. The overall DNA methylation rate at CG (63%), CHG (36%), and CHH (1%) sites based on single base resolution is first reported in strawberry. In addition, a novel MSAP method was established using the isoschizomers Tfi I / Pfe I to detect DNA methylation at CG, CHG, CHH sites based on restriction sites. Further application of this method into the early flowering lines found the maintenance of symmetric CG, CHG methylation over meiotic generations. This project for the first time developed a hypomethylated F. vesca population, comprehensively studied DNA methylation variation of quantitative traits, and the inheritance of these traits through meiosis and mitosis. These data add to the growing evidence that altering epigenetic variation can be a mechanism for generating increased phenotypic diversity and can be subject to selection. This research indicates the potential of crop improvement through epigenetic modification without changing DNA sequence, avoiding the issue of Genetically Modified Organisms

A Cost-Effective Geodetic Strainmeter Based on Dual Coaxial Cable Bragg Gratings

Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in their temporal or spatial resolutions. Here we present a new type of strainmeters based on the coaxial cable Bragg grating (CCBG) sensing technology that provides cost-effective strain measurements. Two CCBGs are introduced into the geodetic strainmeter: one serves as a sensor to measure the strain applied on it, and the other acts as a reference to detect environmental noises. By integrating the sensor and reference signals in a mixer, the environmental noises are minimized and a lower mixed frequency is obtained. The lower mixed frequency allows for measurements to be taken with a portable spectrum analyzer, rather than an expensive spectrum analyzer or a vector network analyzer (VNA). Analysis of laboratory experiments shows that the strain can be measured by the CCBG sensor, and the portable spectrum analyzer can make measurements with the accuracy similar to the expensive spectrum analyzer, whose relative error to the spectrum analyzer R3272 is less than ±0.4%. The outputs of the geodetic strainmeter show a linear relationship with the strains that the CCBG sensor experienced. The measured sensitivity of the geodetic strainmeter is about −0.082 kHz/με; it can cover a large dynamic measuring range up to 2%, and its nonlinear errors can be less than 5.3%

Low birth weight and longitudinal trends of cardiovascular risk factor variables from childhood to adolescence: the bogalusa heart study

BACKGROUND: Several studies have linked low birth weight to adverse levels of cardiovascular risk factors and related diseases. However, information is sparse at a community level in the U.S. general population regarding the effects of low birth weight on the longitudinal trends in cardiovascular risk factor variables measured concurrently from childhood to adolescence. METHODS: Longitudinal analysis was performed retrospectively on data collected from the Bogalusa Heart Study cohort (n = 1141; 57% white, 43% black) followed from childhood to adolescence by repeated surveys between 1973 and 1996. Subjects were categorized into low birth weight (below the race-specific 10(th )percentile; n = 123) and control (between race-specific 50–75(th )percentile; n = 296) groups. RESULTS: Low birth weight group vs control group had lower mean HDL cholesterol (p = 0.05) and higher LDL cholesterol (p = 0.05) during childhood (ages 4–11 years); higher glucose (p = 0.02) during adolescence. Yearly rates of change from childhood to adolescence in systolic blood pressure (p = 0.02), LDL cholesterol (p = 0.05), and glucose (p = 0.07) were faster, and body mass index (p = 0.03) slower among the low birth weight group. In a multivariate analysis, low birth weight was related independently and adversely to longitudinal trends in systolic blood pressure (p = 0.004), triglycerides (p = 0.03), and glucose (p = 0.07), regardless of race or gender. These adverse associations became amplified with age. CONCLUSIONS: Low birth weight is characterized by adverse developmental trends in metabolic and hemodynamic variables during childhood and adolescence; and thus, it may be an early risk factor in this regard

A Model of the Optical Properties of a Non-absorbing Media with Application to Thermotropic Materials for Overheat Protection

AbstractThermotropic materials offer the potential to provide overheat protection for polymer absorbers. These materials are composed of a matrix material in which a second material, referred to as the scattering domain, is dispersed. Temperature control is accomplished by a reduction in transmittance at a desired temperature corresponding to the phase change temperature of the scattering domain. The phase change is accompanied by a change in refractive index. This paper describes a numerical model to predict the transmittance and reflectance of a polymer based thermotropic material as a function of the relative index of refraction m between the matrix and scattering domains, the scattering domain size and volume fraction fv, and the sheet thickness. The thermotropic material is modelled as a non-absorbing sheet comprised of discrete anisotropic scattering spherical particles embedded in a matrix material. Under the assumption that the particles scatter incident radiation independently, the direction of scattered radiation is determined by Mie theory. A Monte Carlo numerical technique is used to predict the transmittance and reflectance for thermotropic materials in which the matrix index of refraction is 1.5 (representative of polymers) and the incident wavelength is 550nm. Model results are validated by comparison to measured transmittance for 0.3mm thick polymer samples containing particles with 200nm radius at m ranging from 0.97 to 1.09 and fv ranging from 5 to 18.2%. As the mismatch in refractive indices and volume fraction increase, the transmittance is reduced. For example, the transmittance is reduced from 83% for m=1.02 and fv = 9.6 to approximately 50% for m=1.09 and fv =13.5% (200nm radius and 0.3mm thick)