211 research outputs found
Pre-M Phase-promoting Factor Associates with Annulate Lamellae in Xenopus Oocytes and Egg Extracts
We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising "annulate lamellae" (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates
Gallbladder microbiota in healthy dogs and dogs with mucocele formation
To date studies have not investigated the culture-independent microbiome of bile from dogs, a species where aseptic collection of bile under ultrasound guidance is somewhat routine. Despite frequent collection of bile for culture-based diagnosis of bacterial cholecystitis, it is unknown whether bile from healthy dogs harbors uncultivable bacteria or a core microbiota. The answer to this question is critical to understanding the pathogenesis of biliary infection and as a baseline to exploration of other biliary diseases in dogs where uncultivable bacteria could play a pathogenic role. A pressing example of such a disease would be gallbladder mucocele formation in dogs. This prevalent and deadly condition is characterized by excessive secretion of abnormal mucus by the gallbladder epithelium that can eventually lead to rupture of the gallbladder or obstruction of bile flow. The cause of mucocele formation is unknown as is whether uncultivable, and therefore unrecognized, bacteria play any systematic role in pathogenesis. In this study we applied next-generation 16S rRNA gene sequencing to identify the culture-negative bacterial community of gallbladder bile from healthy dogs and gallbladder mucus from dogs with mucocele formation. Integral to our study was the use of 2 separate DNA isolations on each sample using different extraction methods and sequencing of negative control samples enabling recognition and curation of contaminating sequences. Microbiota findings were validated by simultaneous culture-based identification, cytological examination of bile, and fluorescence in-situ hybridization (FISH) performed on gallbladder mucosa. Using culture-dependent, cytological, FISH, and 16S rRNA sequencing approaches, results of our study do not support existence of a core microbiome in the bile of healthy dogs or gallbladder mucus from dogs with mucocele formation. Our findings further document how contaminating sequences can significantly contribute to the results of sequencing analysis when performed on samples with low bacterial biomass
Policy masquerading as science: an examination of non-state actor involvement in European risk assessment policy for genetically modified animals
In 2013, at the request of the European Commission, the European Food Safety Authority (EFSA) announced a new risk assessment policy: Guidance on the environmental risks of genetically modified (GM) animals (‘Guidance’). This policy specifies the issues to be addressed in future risk assessments for GM animals. EFSA is the European Commission's scientific arm, responsible for food-related risk assessment. EFSA relies heavily on independent experts and consults non-state actors. Employing expert interviews and documentary analysis, the article explores non-state actor involvement in a traditionally expert domain through a case study. Analysis of EFSA's consultation demonstrates the inability of non-state actors to influence policy. The article argues that despite international legal obligations to develop risk assessment policy, the European Commission failed to recognize the Guidance as policy. When policy masquerades as science, unjustified restrictions are placed on non-state actor involvement and value judgements are cloaked from public scrutiny
Masses and β -Decay Spectroscopy of Neutron-Rich Odd-Odd Eu 160,162 Nuclei: Evidence for a Subshell Gap with Large Deformation at N=98
The structure of deformed neutron-rich nuclei in the rare-earth region is of significant interest for both the astrophysics and nuclear structure fields. At present, a complete explanation for the observed peak in the elemental abundances at A∼160 eludes astrophysicists, and models depend on accurate quantities, such as masses, lifetimes, and branching ratios of deformed neutron-rich nuclei in this region. Unusual nuclear structure effects are also observed, such as the unexpectedly low energies of the first 2+ levels in some even-even nuclei at N=98. In order to address these issues, mass and β-decay spectroscopy measurements of the Eu97160 and Eu99162 nuclei were performed at the Californium Rare Isotope Breeder Upgrade radioactive beam facility at Argonne National Laboratory. Evidence for a gap in the single-particle neutron energies at N=98 and for large deformation (β2∼0.3) is discussed in relation to the unusual phenomena observed at this neutron number
Masses and β -Decay Spectroscopy of Neutron-Rich Odd-Odd Eu 160,162 Nuclei: Evidence for a Subshell Gap with Large Deformation at N=98
The structure of deformed neutron-rich nuclei in the rare-earth region is of significant interest for both the astrophysics and nuclear structure fields. At present, a complete explanation for the observed peak in the elemental abundances at A∼160 eludes astrophysicists, and models depend on accurate quantities, such as masses, lifetimes, and branching ratios of deformed neutron-rich nuclei in this region. Unusual nuclear structure effects are also observed, such as the unexpectedly low energies of the first 2+ levels in some even-even nuclei at N=98. In order to address these issues, mass and β-decay spectroscopy measurements of the Eu97160 and Eu99162 nuclei were performed at the Californium Rare Isotope Breeder Upgrade radioactive beam facility at Argonne National Laboratory. Evidence for a gap in the single-particle neutron energies at N=98 and for large deformation (β2∼0.3) is discussed in relation to the unusual phenomena observed at this neutron number
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Robust diffraction-limited near-infrared-to-near-ultraviolet wide-field imaging from stratospheric balloon-borne platforms — super-pressure balloon-borne imaging telescope performance
At a fraction of the total cost of an equivalent orbital mission, scientific balloon-borne platforms, operating above 99.7% of the Earth’s atmosphere, offer attractive, competitive, and effective observational capabilities—namely, space-like seeing, transmission, and backgrounds—which are well suited for modern astronomy and cosmology. The Super-pressure Balloon-borne Imaging Telescope (SUPERBIT) is a diffraction-limited, wide-field, 0.5 m telescope capable of exploiting these observing conditions in order to provide exquisite imaging throughout the near-infrared to near-ultraviolet. It utilizes a robust active stabilization system that has consistently demonstrated a 48 mas 1σ sky-fixed pointing stability over multiple 1 h observations at float. This is achieved by actively tracking compound pendulations via a three-axis gimballed platform, which provides sky-fixed telescope stability at < 500 mas and corrects for field rotation, while employing high-bandwidth tip/tilt optics to remove residual disturbances across the science imaging focal plane. SUPERBIT’s performance during the 2019 commissioning flight benefited from a customized high-fidelity science-capable telescope designed with an exceptional thermo- and opto-mechanical stability as well as a tightly constrained static and dynamic coupling between high-rate sensors and telescope optics. At the currently demonstrated level of flight performance, SUPERBIT capabilities now surpass the science requirements for a wide variety of experiments in cosmology, astrophysics, and stellar dynamics
Perspectives in visual imaging for marine biology and ecology: from acquisition to understanding
Durden J, Schoening T, Althaus F, et al. Perspectives in Visual Imaging for Marine Biology and Ecology: From Acquisition to Understanding. In: Hughes RN, Hughes DJ, Smith IP, Dale AC, eds. Oceanography and Marine Biology: An Annual Review. 54. Boca Raton: CRC Press; 2016: 1-72
Untangling creativity and art for policy purposes : ethnographic insights on Manchester International Festival and Manchester Day Parade
This paper draws on anthropological fieldwork of a civic parade in Manchester
from 2010 to 2012 to argue for engaging with creativity as a process rather
than an attribute of a particular sector or individual. It shows how the focus on
funding and supporting ‘creative industries’ defined as ‘cinema, television,
music, literature, performing arts, heritage and related areas’ actually excludes
and diminishes the potential for others to engage with ideas and creative
processes. Two major events in Manchester’s cultural calendar – Procession by
artist Jeremy Deller, produced by Manchester International Festival and
Manchester Day Parade, a council-led civic celebration – both combined community
groups with artist input to put large-scale structures and people on the
city’s streets. In this ethnographic analysis, I argue that the ‘creativity’ sought
from these artists is their adaptive and productive approach to making ideas tangible.
By focusing on creativity as a process rather than a character trait, there
is even greater potential for stimulating a ‘creative’ city
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