Specific proteins potentially associated with somatic embryogenesis in orchardgrass

Various biotechnological techniques studied to supplement conventional plant breeding procedures require the regeneration of whole plants from cells or tissue cultured in vitro. The objective of this study with orchardgrass (Dactylis glomerata L.) was to investigate specific protein differences associated with \u27Embryogen-P\u27, a genotype which produces somatic embryos in high numbers, and four nonembryogenic genotypes by one-and two-dimensional polyacrylamide gel electrophoresis. Four proteins were present in Embryogen-P leaves that were not present in the leaves of the nonembryogenic genotypes. One protein appeared in the nonembryogenic genotypes that did not appear in Embryogen-P. Similar results were found in the embryogenic and nonembryogenic progeny of a cross between Embryogen-P and one of the nonembryogenic genotypes. These results support an association of specific proteins with the ability to produce somatic embryos. Embryogenesis was supported in suspension cultures by the addition of casein hydrolysate to the medium. Five proteins were found in the protein profiles of these cultures that were not present in those not supporting embryogenesis. Similar results were obtained in a second experiment using (NH4)2SO4 to support enbryogenesis. Although these proteins may not be directly involved in embryogenesis, they appear to be associated with the process. Basal sections of Embryogen-P leaves were analyzed after 2, 4, 7, 10, 14, or 22 d after culture. A total of 12 proteins were found to be produced during culture, 9 at 7 d, 2 at 10 d, and 1 at 14 d after culture. Appearance of these proteins at different times throughout the culture period suggests a time course for their synthesis. Leaves were placed on medium with abscisic acid (ABA) and removed at 1, 2, or 3 d after culture. Four proteins were found in leaves 1 d after culture and three were present after 2 d. Three proteins found in leaves 1 d after culture with ABA had the same molecular weights as three appearing at 7 d after culture on medium without ABA. These three may be promoted at an earlier time by ABA and produced in response to embryogenesis

Mapping Burn Severity using the Composite Burn Index in an Oak Savannah in Central Massachusetts

The goal of this paper is to characterize the spatial variability in burn severity of a wildfire in an oak savannah within the wildland-urban interface in Worcester, Massachusetts using the Composite Burn Index (CBI). This work compares two interpolated surfaces of burn severity values collected in a March 2012 burn area and examines the statistical relationship between burn severity (CBI), fuel type and topography. The wildfire burned at low-to-medium severity (0.1 – 2.0 CBI). Burn severity was highest in mixed grass and shrub fuels beneath oak canopy cover (mean 1.11 CBI), followed by open-canopy shrub fuels (mean 1.09 CBI) and then open-canopy grass fuels (mean 1.06 CBI). Burn severity was negatively correlated with elevation (r2 = -0.22) and slope (r2 = -0.04). These results, coupled with recently acquired historical fire records, presents the first comprehensive fire analysis of the site and indicates the need for a burn and fuel reduction progra

Subclinical Hypothyroidism after Radioiodine Exposure: Ukrainian–American Cohort Study of Thyroid Cancer and Other Thyroid Diseases after the Chornobyl Accident (1998–2000)

BackgroundHypothyroidism is the most common thyroid abnormality in patients treated with high doses of iodine-131 (131I). Data on risk of hypothyroidism from low to moderate 131I thyroid doses are limited and inconsistent.ObjectiveThis study was conducted to quantify the risk of hypothyroidism prevalence in relation to 131I doses received because of the Chornobyl accident.MethodsThis is a cross-sectional (1998-2000) screening study of thyroid diseases in a cohort of 11,853 individuals < 18 years of age at the time of the accident, with individual thyroid radioactivity measurements taken within 2 months of the accident. We measured thyroid-stimulating hormone (TSH), free thyroxine, and antibodies to thyroid peroxidase (ATPO) in serum.ResultsMean age at examination of the analysis cohort was 21.6 years (range, 12.2-32.5 years), with 49% females. Mean 131I thyroid dose was 0.79 Gy (range, 0-40.7 Gy). There were 719 cases with hypothyroidism (TSH > 4 mIU/L), including 14 with overt hypothyroidism. We found a significant, small association between (131)I thyroid doses and prevalent hypothyroidism, with the excess odds ratio (EOR) per gray of 0.10 (95% confidence interval, 0.03-0.21). EOR per gray was higher in individuals with ATPO < or = 60 U/mL compared with individuals with ATPO > 60 U/mL (p < 0.001).ConclusionsThis is the first study to find a significant relationship between prevalence of hypothyroidism and individual (131)I thyroid doses due to environmental exposure. The radiation increase in hypothyroidism was small (10% per Gy) and limited largely to subclinical hypothyroidism. Prospective data are needed to evaluate the dynamics of radiation-related hypothyroidism and clarify the role of antithyroid antibodies

I-131 Dose Response for Incident Thyroid Cancers in Ukraine Related to the Chornobyl Accident

Background: Current knowledge about Chornobyl-related thyroid cancer risks comes from ecological studies based on grouped doses, case–control studies, and studies of prevalent cancers

Aptamer base: a collaborative knowledge base to describe aptamers and SELEX experiments

Over the past several decades, rapid developments in both molecular and information technology have collectively increased our ability to understand molecular recognition. One emerging area of interest in molecular recognition research includes the isolation of aptamers. Aptamers are single-stranded nucleic acid or amino acid polymers that recognize and bind to targets with high affinity and selectivity. While research has focused on collecting aptamers and their interactions, most of the information regarding experimental methods remains in the unstructured and textual format of peer reviewed publications. To address this, we present the Aptamer Base, a database that provides detailed, structured information about the experimental conditions under which aptamers were selected and their binding affinity quantified. The open collaborative nature of the Aptamer Base provides the community with a unique resource that can be updated and curated in a decentralized manner, thereby accommodating the ever evolving field of aptamer research

Association between exposure to radioactive iodine after the Chernobyl accident and thyroid volume in Belarus 10-15 years later

Background: While there is a robust literature on environmental exposure to iodine-131 (131I) in childhood and adolescence and the risk of thyroid cancer and benign nodules, little is known about its effects on thyroid volume. Methods: To assess the effect of 131I dose to the thyroid on the volume of the thyroid gland, we examined the data from the baseline screening of the Belarusian-American Cohort Study of residents of Belarus who were exposed to the Chernobyl fallout at ages ≤18 years. Thyroid dose estimates were based on individual thyroid activity measurements made shortly after the accident and dosimetric data from questionnaires obtained 10-15 years later at baseline screening. During baseline screening, thyroid gland volume was assessed from thyroid ultrasound measurements. The association between radiation dose and thyroid volume was modeled using linear regression where radiation dose was expressed with power terms to address non-linearity. The model was adjusted for attained age, sex, and place of residence, and their modifying effects were examined. Results: The analysis was based on 10,703 subjects. We found a statistically significant positive association between radiation dose and thyroid volume (P \u3c 0.001). Heterogeneity of association was observed by attained age (P \u3c 0.001) with statistically significant association remaining only in the subgroup of ≥18 years at screening (P \u3c 0.001). For this group, increase in dose from 0.0005 to 0.15 Gy was associated with a 1.27 ml (95% CI: 0.46, 2.07) increase in thyroid volume. The estimated effect did not change with increasing doses above 0.15 Gy. Conclusions: This is the first study to examine the association between 131I dose to the thyroid gland and thyroid volume in a population of individuals exposed during childhood and systematically screened 10-15 years later. It provides evidence for a moderate statistically significant increase in thyroid volume among those who were ≥ 18 years at screening. Given that this effect was observed at very low doses and was restricted to a narrow dose range, further studies are necessary to better understand the effect

On the Choice of Functional Form for Hedonic Price Functions.

This study examines how errors in measuring marginal attribute pric es vary with the form of the hedonic price function. In simulations, consumers with known utility functions bid for houses with given attributes. Various forms of the hedonic function are estimated using equilibrium housing prices. Errors in estimating marginal attribute prices are calculated by comparing each consumer's equilibrium marginal bid vector with the gradient of the hedonic function. When all attributes are observed, linear and quadratic Box-Cox forms produce lowest mean percentage errors; however, when some attributes are unobserved or are replaced by proxies, linear and linear Box-Cox functions perform best. Copyright 1988 by MIT Press.

Thresholds for phosphatidylserine externalization in Chinese hamster ovarian cells following exposure to nanosecond pulsed electrical fields (nsPEF).

High-amplitude, MV/m, nanosecond pulsed electric fields (nsPEF) have been hypothesized to cause nanoporation of the plasma membrane. Phosphatidylserine (PS) externalization has been observed on the outer leaflet of the membrane shortly after nsPEF exposure, suggesting local structural changes in the membrane. In this study, we utilized fluorescently-tagged Annexin V to observe the externalization of PS on the plasma membrane of isolated Chinese Hamster Ovary (CHO) cells following exposure to nsPEF. A series of experiments were performed to determine the dosimetric trends of PS expression caused by nsPEF as a function of pulse duration, τ, delivered field strength, ED, and pulse number, n. To accurately estimate dose thresholds for cellular response, data were reduced to a set of binary responses and ED50s were estimated using Probit analysis. Probit analysis results revealed that PS externalization followed the non-linear trend of (τ*ED (2))(-1) for high amplitudes, but failed to predict low amplitude responses. A second set of experiments was performed to determine the nsPEF parameters necessary to cause observable calcium uptake, using cells preloaded with calcium green (CaGr), and membrane permeability, using FM1-43 dye. Calcium influx and FM1-43 uptake were found to always be observed at lower nsPEF exposure parameters compared to PS externalization. These findings suggest that multiple, higher amplitude and longer pulse exposures may generate pores of larger diameter enabling lateral diffusion of PS; whereas, smaller pores induced by fewer, lower amplitude and short pulse width exposures may only allow extracellular calcium and FM1-43 uptake

Lack of Dehydroepiandrosterone Effect on a Combined Endurance and Resistance Exercise Program in Postmenopausal Women

Context: Recent studies disputed the widely promoted anti-aging effect of dehydroepiandrosterone (DHEA) supplementation; however, conflicting data exist on whether physiological DHEA supplementation enhances exercise training effects on body composition, physical performance, and cardiometabolic risk in healthy postmenopausal women