Pex7p translocates in and out of peroxisomes in Saccharomyces cerevisiae

Pex7p is the soluble receptor responsible for importing into peroxisomes newly synthesized proteins bearing a type 2 peroxisomal targeting sequence. We observe that appending GFP to Pex7p's COOH terminus shifts Pex7p's intracellular distribution from predominantly cytosolic to predominantly peroxisomal in Saccharomyces cerevisiae. Cleavage of the link between Pex7p and GFP within peroxisomes liberates GFP, which remains inside the organelle, and Pex7p, which exits to the cytosol. The reexported Pex7p is functional, resulting in import of thiolase into peroxisomes and improved growth of the yeast on oleic acid. These results support the “extended shuttle” model of peroxisome import receptor function and open the way to future studies of receptor export

Genetic heterogeneity of white-tailed deer: management lessons from a long-term study

Genetic data from a long-term (16-year) study of white-tailed deer (Odocoileus virginianus) on the U.S. Department of Energy\u27s Savannah River Site (SRS) were examined to evaluate spatial and temporal genetic heterogeneity in this species. Based on our analyses of the long-term data set, three major findings emerged, all of which have important implications for management of white-tailed deer: (1) There exists significant spatial genetic heterogeneity in white-tailed deer based on analyses of allozyme frequencies and mtDNA haplotypes. This heterogeneity exists on a much smaller spatial scale than would be expected for such a large and potentially mobile species as 0. virginianus. (2) The genetic structure of white-tailed deer at SRS is temporally dynamic and significant heterogeneity exists within demographic units such as age and sex classes. (3) Levels of genetic variation, as measured by multilocus heterozygosity, are frequently correlated to characteristics that are important determinants of ecological function in white-tailed deer populations. These findings are evaluated in the context of a general management model for 0. virginianus that is also applicable to other wildlife species

Circulating resistin levels and risk of multiple myeloma in three prospective cohorts

BACKGROUND: Resistin is a polypeptide hormone secreted by adipose tissue. A prior hospital-based case-control study reported serum resistin levels to be inversely associated with risk of multiple myeloma (MM). To date, this association has not been investigated prospectively. METHODS: We measured resistin concentrations for pre-diagnosis peripheral blood samples from 178 MM cases and 358 individually matched controls from three cohorts participating in the MM cohort consortium. RESULTS: In overall analyses, higher resistin levels were weakly associated with reduced MM risk. For men, we observed a statistically significant inverse association between resistin levels and MM (odds ratio, 0.44; 95% confidence interval (CI) 0.24-0.83 and 0.54; 95% CI 0.29-0.99, for the third and fourth quartiles, respectively, vs the lowest quartile; Ptrend=0.03). No association was observed for women. CONCLUSIONS: This study provides the first prospective evidence that low circulating resistin levels may be associated with an increased risk of MM, particularly for men

High levels of fluctuating asymmetry in populations of Apodemus flavicollis from the most contaminated areas in Chornobyl

Random deviations from the perfect symmetry of normally bilaterally symmetrical characters for an individual with a given genotype occur during individual development due to the influence of multiple environmental factors. Fluctuating asymmetry (FA) is often used as a measure of developmental instability, and can be estimated as the variance of the distribution of differences between the left and right sides. We addressed the question of whether levels of FA were elevated in radioactively contaminated populations living around Chornobyl compared to those in reference populations of the yellow-necked mouse (Apodemus flavicollis). In addition, we studied amounts of directional asymmetry (DA) when one side is larger than the other on average. There was a significant difference among populations, including reference populations, in the amount of both FA and DA. A higher level of FA was documented for the contaminated populations in close proximity to the failed Chornobyl reactor for both the asymmetry of size and shape. The FAs of size and shape were highest in populations from the most contaminated locations in the Chornobyl exclusion zone. Although the directional asymmetry of shape was also highest in the contaminated populations, it was not significantly different from those in most of the reference populations. Populations from less contaminated areas inside the Chornobyl exclusion zone did not express FA values different from those of the reference populations outside the affected area

Problems with developmental stability in two rodent species from Chornobyl

Changes in developmental patterns are some of the most important effects that may be observed at radioactively contaminated sites like those at Chornobyl. Developmental instability may arise from the interactions between an organism\u27s genotype and its environment and be manifested as deviant morphology. Fluctuating asymmetry (FA) is a measure of deviations from the expected bilateral symmetry of the body. Our objective was to test for differences in FA in two rodent species (Apodemus flavicollis and Clethrionomys glareolus) that live in habitats suirounding the failed Chornobyl reactor. Rodents were collected from four different locations (two contaminated and two reference sites), and a series of adult skulls were photographed and 24 landmarks on each skull were located on digital images from photographed skulls. FA was calculated from the differences in these landmarks on the right and left side of the skull. Significantly more asymmetry (~2X) was observed in mice and voles living around Chornobyl compared to those living at the uncontaminated reference sites. These are relatively large effects in comparison to those previously found for plants and swallows. FA can be a cheap, easily determined and sensitive indicator of radiation-induced stress in small mammals. FA can be used to prioritize environments for remediation efforts and to efficiently evaluate the effectiveness of the remediation efforts

Problems with developmental stability in two rodent species from Chornobyl

Changes in developmental patterns are some of the most important effects that may be observed at radioactively contaminated sites like those at Chornobyl. Developmental instability may arise from the interactions between an organism\u27s genotype and its environment and be manifested as deviant morphology. Fluctuating asymmetry (FA) is a measure of deviations from the expected bilateral symmetry of the body. Our objective was to test for differences in FA in two rodent species (Apodemus flavicollis and Clethrionomys glareolus) that live in habitats suirounding the failed Chornobyl reactor. Rodents were collected from four different locations (two contaminated and two reference sites), and a series of adult skulls were photographed and 24 landmarks on each skull were located on digital images from photographed skulls. FA was calculated from the differences in these landmarks on the right and left side of the skull. Significantly more asymmetry (~2X) was observed in mice and voles living around Chornobyl compared to those living at the uncontaminated reference sites. These are relatively large effects in comparison to those previously found for plants and swallows. FA can be a cheap, easily determined and sensitive indicator of radiation-induced stress in small mammals. FA can be used to prioritize environments for remediation efforts and to efficiently evaluate the effectiveness of the remediation efforts

Sagnac Interferometer as a Speed-Meter-Type, Quantum-Nondemolition Gravitational-Wave Detector

According to quantum measurement theory, "speed meters" -- devices that measure the momentum, or speed, of free test masses -- are immune to the standard quantum limit (SQL). It is shown that a Sagnac-interferometer gravitational-wave detector is a speed meter and therefore in principle it can beat the SQL by large amounts over a wide band of frequencies. It is shown, further, that, when one ignores optical losses, a signal-recycled Sagnac interferometer with Fabry-Perot arm cavities has precisely the same performance, for the same circulating light power, as the Michelson speed-meter interferometer recently invented and studied by P. Purdue and the author. The influence of optical losses is not studied, but it is plausible that they be fairly unimportant for the Sagnac, as for other speed meters. With squeezed vacuum (squeeze factor $e^{-2R} = 0.1$) injected into its dark port, the recycled Sagnac can beat the SQL by a factor $\sqrt{10} \simeq 3$ over the frequency band 10 {\rm Hz} \alt f \alt 150 {\rm Hz} using the same circulating power $I_c\sim 820$ kW as is used by the (quantum limited) second-generation Advanced LIGO interferometers -- if other noise sources are made sufficiently small. It is concluded that the Sagnac optical configuration, with signal recycling and squeezed-vacuum injection, is an attractive candidate for third-generation interferometric gravitational-wave detectors (LIGO-III and EURO).Comment: 12 pages, 6 figure

A Comparative Study of the Properties of Polar and Nonpolar Solvent/Solute/Polystyrene Solutions in Microwave Fields Via Molecular Dynamics

The influence of an applied microwave field on the dynamics of methylamine-dichloromethane (DCM) mixtures bound within atactic polystyrene (a-PS) over a range of polymer densities from 30 to 94 wt % polymer was examined using atomistic molecular dynamics simulations. This study is an extension of previous studies on methylamine transport in relatively polar polystyrene solutions of methanol and dimethylformamide [M. J. Purdue et al., J. Chem. Phys. 124, 204904 (2006)]. A direct comparison is made across the three types of polystyrene solutions. Consideration is given to both solvent and reagent transport within the polymer solutions under zero-field conditions and in an external electromagnetic field in the canonical ensemble (NVT) at 298.0 K. Various frequencies up to 104 GHz and a rms electric field intensity of 0.1 V/Å were applied. The simulation studies were validated by comparison of the simulated zero-field self-diffusion coefficients of DCM in a-PS with those obtained using pulsed-gradient spin-echo NMR spectrometry. Athermal effects of microwave fields on solute transport behavior within polymer solutions are discussed

Quantum noise in laser-interferometer gravitational-wave detectors with a heterodyne readout scheme

We analyze and discuss the quantum noise in signal-recycled laser interferometer gravitational-wave detectors, such as Advanced LIGO, using a heterodyne readout scheme and taking into account the optomechanical dynamics. Contrary to homodyne detection, a heterodyne readout scheme can simultaneously measure more than one quadrature of the output field, providing an additional way of optimizing the interferometer sensitivity, but at the price of additional noise. Our analysis provides the framework needed to evaluate whether a homodyne or heterodyne readout scheme is more optimal for second generation interferometers from an astrophysical point of view. As a more theoretical outcome of our analysis, we show that as a consequence of the Heisenberg uncertainty principle the heterodyne scheme cannot convert conventional interferometers into (broadband) quantum non-demolition interferometers.Comment: 16 pages, 8 figure