Bioenergetic Profiling of Zebrafish Embryonic Development

Many debilitating conditions are linked to bioenergetic defects. Developing screens to probe the genetic and/or chemical basis for such links has proved intractable. Furthermore, there is a need for a physiologically relevant assay of bioenergetics in whole organisms, especially for early stages in life where perturbations could increase disease susceptibility with aging. Thus, we asked whether we could screen bioenergetics and mitochondrial function in the developing zebrafish embryo. We present a multiplexed method to assay bioenergetics in zebrafish embryos from the blastula period (3 hours post-fertilization, hpf) through to hatching (48 hpf). In proof of principle experiments, we measured respiration and acid extrusion of developing zebrafish embryos. We quantified respiratory coupling to various bioenergetic functions by using specific pharmacological inhibitors of bioenergetic pathways. We demonstrate that changes in the coupling to ATP turnover and proton leak are correlated with developmental stage. The multiwell format of this assay enables the user to screen for the effects of drugs and environmental agents on bioenergetics in the zebrafish embryo with high sensitivity and reproducibility

A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests

A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Agency's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar(TradeMark) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar(TradeMark) filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However, due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to the experimental investigation reported in [1] and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel's residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV hardware

Plasmodium vivax Adherence to Placental Glycosaminoglycans

BACKGROUND: Plasmodium vivax infections seldom kill directly but do cause indirect mortality by reducing birth weight and causing abortion. Cytoadherence and sequestration in the microvasculature are central to the pathogenesis of severe Plasmodium falciparum malaria, but the contribution of cytoadherence to pathology in other human malarias is less clear. METHODOLOGY: The adherence properties of P. vivax infected red blood cells (PvIRBC) were evaluated under static and flow conditions. PRINCIPAL FINDINGS: P. vivax isolates from 33 patients were studied. None adhered to immobilized CD36, ICAM-1, or thrombospondin, putative ligands for P. falciparum vascular cytoadherence, or umbilical vein endothelial cells, but all adhered to immobilized chondroitin sulphate A (CSA) and hyaluronic acid (HA), the receptors for adhesion of P. falciparum in the placenta. PvIRBC also adhered to fresh placental cells (N = 5). Pre-incubation with chondroitinase prevented PvIRBC adherence to CSA, and reduced binding to HA, whereas preincubation with hyaluronidase prevented adherence to HA, but did not reduce binding to CSA significantly. Pre-incubation of PvIRBC with soluble CSA and HA reduced binding to the immobilized receptors and prevented placental binding. PvIRBC adhesion was prevented by pre-incubation with trypsin, inhibited by heparin, and reduced by EGTA. Under laminar flow conditions the mean (SD) shear stress reducing maximum attachment by 50% was 0.06 (0.02) Pa but, having adhered, the PvIRBC could then resist detachment by stresses up to 5 Pa. At 37 °C adherence began approximately 16 hours after red cell invasion with maximal adherence at 30 hours. At 39 °C adherence began earlier and peaked at 24 hours. SIGNIFICANCE: Adherence of P. vivax-infected erythrocytes to glycosaminoglycans may contribute to the pathogenesis of vivax malaria and lead to intrauterine growth retardation

An Ecologic Analysis of County-Level PM2.5 Concentrations and Lung Cancer Incidence and Mortality

Few studies have explored the relationship between PM2.5 and lung cancer incidence. Although results are mixed, some studies have demonstrated a positive relationship between PM2.5 and lung cancer mortality. Using an ecologic study design, we examined the county-level associations between PM2.5 concentrations (2002–2005) and lung cancer incidence and mortality in North Carolina (2002–2006). Positive trends were observed between PM2.5 concentrations and lung cancer incidence and mortality; however, the R2 for both were <0.10. The slopes for the relationship between PM2.5 and lung cancer incidence and mortality were 1.26 (95% CI 0.31, 2.21, p-value 0.01) and 0.73 (95% CI 0.09, 1.36, p-value 0.03) per 1 μg/m3 PM2.5, respectively. These associations were slightly strengthened with the inclusion of variables representing socioeconomic status and smoking. Although variability is high, thus reflecting the importance of tobacco smoking and other etiologic agents that influence lung cancer incidence and mortality besides PM2.5, a positive trend is observed between PM2.5 and lung cancer incidence and mortality. This suggests the possibility of an association between PM2.5 concentrations and lung cancer incidence and mortality

AChR deficiency due to ε-subunit mutations: two common mutations in the Netherlands

Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of hereditary disorders affecting neuromuscular transmission. We have identified mutations within the acetylcholine receptor (AChR) ε-subunit gene underlying congenital myasthenic syndromes in nine patients (seven kinships) of Dutch origin. Previously reported mutations ε1369delG and εR311Q were found to be common; ε1369delG was present on at least one allele in seven of the nine patients, and εR311Q in six. Phenotypes ranged from relatively mild ptosis and external ophthalmoplegia to generalized myasthenia. The common occurrence of εR311Q and ε1369delG suggests a possible founder for each of these mutations originating in North Western Europe, possibly in Holland. Knowledge of the ethnic or geographic origin within Europe of AChR deficiency patients can help in targeting genetic screening and it may be possible to provide a rapid genetic diagnosis for patients of Dutch origin by screening first for εR311Q and ε1369delG

Identification and validation of genetic variants predictive of gait in standardbred horses

Several horse breeds have been specifically selected for the ability to exhibit alternative patterns of locomotion, or gaits. A premature stop codon in the gene DMRT3 is permissive for “gaitedness” across breeds. However, this mutation is nearly fixed in both American Standardbred trotters and pacers, which perform a diagonal and lateral gait, respectively, during harness racing. This suggests that modifying alleles must influence the preferred gait at racing speeds in these populations. A genome-wide association analysis for the ability to pace was performed in 542 Standardbred horses (n = 176 pacers, n = 366 trotters) with genotype data imputed to ~74,000 single nucleotide polymorphisms (SNPs). Nineteen SNPs on nine chromosomes (ECA1, 2, 6, 9, 17, 19, 23, 25, 31) reached genome-wide significance (p < 1.44 x 10−6). Variant discovery in regions of interest was carried out via whole-genome sequencing. A set of 303 variants from 22 chromosomes with putative modifying effects on gait was genotyped in 659 Standardbreds (n = 231 pacers, n = 428 trotters) using a high-throughput assay. Random forest classification analysis resulted in an out-of-box error rate of 0.61%. A conditional inference tree algorithm containing seven SNPs predicted status as a pacer or trotter with 99.1% accuracy and subsequently performed with 99.4% accuracy in an independently sampled population of 166 Standardbreds (n = 83 pacers, n = 83 trotters). This highly accurate algorithm could be used by owners/trainers to identify Standardbred horses with the potential to race as pacers or as trotters, according to the genotype identified, prior to initiating training and would enable fine-tuning of breeding programs with designed matings. Additional work is needed to determine both the algorithm’s utility in other gaited breeds and whether any of the predictive SNPs play a physiologically functional role in the tendency to pace or tag true functional alleles

Spatially limited mud turbidites on the Cascadia margin: segmented earthquake ruptures?

Abstract: A series of 23 thin, mostly mud-silt turbidites are found interspersed between larger, well-dated and regionally correlated paleoseismic sandy turbidites that extend along most of the Cascadia margin, northwestern United States. Investigation of the structure, distribution, and sedimentology of these thin mud-silt units supports the interpretation of these units as turbidites originating on the continental slope. Interpretation of mud turbidites is inhibited by bioturbation and lower response to analytical and imaging techniques; nevertheless most of the 23 interpreted beds exhibit most of the characteristics of coarser turbidites. These characteristics include sharp bases, fining upward sequences, darker color, increased gamma and CT density and magnetic susceptibility relative to the hemipelagic background, sparse microfossils, high lithic content, and evidence of transport from marine sources on the continental slope. New core data from sites south of Rogue Apron indicate that sandy and muddy turbidites may be correlated at least 150 km south to Trinidad Plunge Pool for the period similar to 4800 yr BP to present. Many of the mud turbidites initially described at Rogue Apron coarsen southward, becoming sandy turbidites. High-resolution Chirp seismic profiles reveal that turbidite stratigraphy along the base of the southern Cascadia continental slope is continuous, with little variation for at least 240 km along strike. The Chirp data show that turbidites along the Cascadia base of slope are ubiquitous, and likely not sourced solely from submarine canyon mouths, but may also have been delivered to the proximal abyssal plain as sheet flows from the open continental slope and coalescing local sources. Regional stratigraphy reveals that hemipelagic sedimentation rates and total Holocene turbidite thickness and mass are similar at widely separated sites, yet the total thickness of the Holocene section is greater by a factor of two in southern Cascadia. This difference is primarily due to the presence of the 21 mud and two additional sandy turbidites. We conclude that the Cascadia mud turbidites are ubiquitous along southern Cascadia only, with only one likely example of a correlated turbidite limited to the northern margin. Eight onshore sites including three marsh sites and five lakes include potential seismogenic correlatives of the southern Cascadia turbidites. In all, the onshore sites may have recorded > 80% of the events attributed to plate boundary earthquakes offshore during the period 0-6000 yr ago. Slope stability calculations suggest that earthquakes of M-W = 7.0 or greater should generate ground accelerations sufficient to destabilize open slopes and canyon heads with or without excess pore fluid pressure. Estimates of Mw for segmented ruptures are in the range of 7.4-8.7, exceeding the slope stability criteria for typical slopes by at least a factor of similar to four.Keywords: Northern California, Physical properties, Radiocarbon age calibration, California Continental-Margin, Subduction zone, San Andreas Faul