Mobility and Degradation of Pesticides and Their Degradates in Intact Soil Columns

Laboratory studies were conducted to determine the mobility of parent pesticides and degradation products through the use of large undisturbed soil columns. The influence of vegetation on the mobility of pesticide adjuvants was also investigated. Modifications to the laboratory setup of soil columns for studying various pesticides, degradation products, and adjuvants were done to fit the needs of the particular compound being studied. To improve mass balances of volatile parent compounds, such as methyl bromide, as well as biodegradable (mineralizable) pesticide degradation products such as deethylatrazine, modifications of columns to accommodate isolation of volatile degradation products were accomplished by enclosure of the column head space and use of flow-through systems. Evidence of preferential flow of atrazine, deethylatrazine, metolachlor, and methyl bromide were indicated by the presence of either the 14C-compound or Br-(in the case of methyl bromideapplied soil columns) after the first leaching event. Diffusion through the soil matrix was also evident with a peak of14C in the leachate several weeks after pesticide (or degradate) application to the soil column. Deethylatrazine, a major degradate of atrazine, was more mobile than the parent compound. Vegetation had a significant positive effect on reducing the mobility of the adjuvants propylene glycol and ethylene glycol

The unique radar scattering properties of silicic lava flows and domes

Silicic (silica-rich) lava flows, such as rhyolite, rhyodacite, and dacite, possess unique physical properties primarily because of the relatively high viscosity of the molten lava. Silicic flows tend to be thicker than basaltic flows, and the resulting large-scale morphology is typically a steep-sided dome or flow lobe, with aspect ratios (height/length) sometimes approaching unity. The upper surfaces of silicic domes and flows are normally emplaced as relatively cool, brittle slabs that fracture as they are extruded from the central vent areas, and are then rafted away toward the flow margin as a brittle carapace above a more ductile interior layer. This mode of emplacement results in a surface with unique roughness characteristics, which can be well-characterized by multiparameter synthetic aperture radar (SAR) observations. In this paper, we examine the scattering properties of several silicic domes in the Inyo volcanic chain in the Eastern Sierra of California, using AIRSAR and TOPSAR data. Field measurements of intermediate-scale (cm to tens of m) surface topography and block size are used to assess the mechanisms of the scattering process, and to quantify the unique roughness characteristics of the flow surfaces

Constitutive Expression of PU.1 in Fetal Hematopoietic Progenitors Blocks T Cell Development at the Pro-T Cell Stage

AbstractThe essential hematopoietic transcription factor PU.1 is expressed in multipotent thymic precursors but downregulated during T lineage commitment. The significance of PU.1 downregulation was tested using retroviral vectors to force hematopoietic precursors to maintain PU.1 expression during differentiation in fetal thymic organ culture. PU.1 reduced thymocyte expansion and blocked development at the pro-T cell stage. PU.1-expressing cells could be rescued by switching to conditions permissive for macrophage development; thus, the inhibition depends on both lineage and developmental stage. An intact DNA binding domain was required for these effects. PU.1 expression can downregulate pre-Tα, Rag-1, and Rag-2 in a dose-dependent manner, and higher PU.1 levels induce Mac-1 and Id-2. Thus, downregulation of PU.1 is specifically required for progression in the T cell lineage

Subversion of T lineage commitment by PU.1 in a clonal cell line system

Specification of mammalian T lymphocytes involves prolonged developmental plasticity even after lineage-specific gene expression begins. Expression of transcription factor PU.1 may maintain some myeloid-like developmental alternatives until commitment. Commitment could reflect PU.1 shutoff, resistance to PU.1 effects, and/or imposition of a suicide penalty for diversion. Here, we describe subclones from the SCID.adh murine thymic lymphoma, adh.2C2 and adh.6D4, that represent a new tool for probing these mechanisms. PU.1 can induce many adh.2C2 cells to undergo diversion to a myeloid-like phenotype, in an all-or-none fashion with multiple, coordinate gene expression changes; adh.6D4 cells resist diversion, and most die. Diversion depends on the PU.1 Ets domain but not on known interactions in the PEST or Q-rich domains, although the Q-rich domain enhances diversion frequency. Protein kinase C/MAP kinase stimulation can make adh.6D4 cells permissive for diversion without protecting from suicide. These results show distinct roles for regulated cell death and another stimulation-sensitive function that establishes a threshold for diversion competence. PU.1 also diverts normal T-cell precursors from wild type or Bcl2-transgenic mice to a myeloid-like phenotype, upon transduction in short-term culture. The adh.2C2 and adh.6D4 clones thus provide an accessible system for defining mechanisms controlling developmental plasticity in early T-cell development

What Does Weight Have to Do with It? Parent Perceptions of Weight and Pain in a Pediatric Chronic Pain Population

Tailored pain management strategies are urgently needed for youth with co-occurring chronic pain and obesity; however, prior to developing such strategies, we need to understand parent perspectives on weight in the context of pediatric chronic pain. Participants in this study included 233 parents of patients presenting to a multidisciplinary pediatric chronic pain clinic. Parents completed a brief survey prior to their child\u27s initial appointment; questions addressed parents\u27 perceptions of their child\u27s weight, and their perceptions of multiple aspects of the relationship between their child\u27s weight and chronic pain. The majority (64%) of parents of youth with obesity accurately rated their child\u27s weight; this group of parents was also more concerned (p \u3c 0.05) about their child\u27s weight than parents of youth with a healthy weight. However, the majority of parents of youth with obesity did not think their child\u27s weight contributed to his/her pain, or that weight was relevant to their child\u27s pain or pain treatment. Overall, only half of all parents saw discussions of weight, nutrition, and physical activity as important to treating their child\u27s pain. Results support the need for addressing parents\u27 perceptions of their child\u27s weight status, and educating parents about the relationship between excessive weight and chronic pain

Assessment of abdominal fat compartments using DXA in premenopausal women from anorexia nervosa to morbid obesity

Objective: The purpose of this study was to test a newly developed DXA method for abdominal fat depot quantification in subjects with AN, normal weight, and obesity using CT as a gold standard. Design and Methods 135 premenopausal women (overweight/obese: n=89, normal-weight: n=27, AN: n=19); abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT) areas determined on CT and DXA. Results: There were strong correlations between DXA and CT measurements of abdominal fat compartments in all groups with the strongest correlation coefficients in the normal-weight and overweight/obese groups. Correlations of DXA and CT VAT measurements were strongest in the obese group and weakest in the AN group. DXA abdominal fat depots were higher in all groups compared to CT, with the largest % mean difference in the AN group and smallest in the obese group. Conclusions: A new DXA technique is able to assess abdominal fat compartments including VAT in premenopausal women across a large weight spectrum However, DXA measurements of abdominal fat were higher than CT, and this percent bias was most pronounced in the AN subjects and decreased with increasing weight, suggesting that this technique may be more useful in obese individuals

Chytrid epidemics may increase genetic diversity of a diatom spring-bloom

Contrary to expectation, populations of clonal organisms are often genetically highly diverse. In phytoplankton, this diversity is maintained throughout periods of high population growth (that is, blooms), even though competitive exclusion among genotypes should hypothetically lead to the dominance of a few superior genotypes. Genotype-specific parasitism may be one mechanism that helps maintain such high-genotypic diversity of clonal organisms. Here, we present a comparison of population genetic similarity by estimating the beta-dispersion among genotypes of early and peak bloom populations of the diatom Asterionella formosa for three spring-blooms under high or low parasite pressure. The Asterionella population showed greater beta-dispersion at peak bloom than early bloom in the 2 years with high parasite pressure, whereas the within group dispersion did not change under low parasite pressure. Our findings support that high prevalence parasitism can promote genetic diversification of natural populations of clonal hosts

Special theme article : science and sociology of footwear

Journal editorial