309 research outputs found
Extensive collection of femtoliter pad secretion droplets in beetle Leptinotarsa decemlineata allows nanoliter microrheology
Pads of beetles are covered with long, deformable setae, each ending in a
micrometric terminal plate coated with secretory fluid. It was recently shown
that the layer of the pad secretion covering the terminal plates is responsible
for the generation of strong attractive forces. However, less is known about
the fluid itself because it is produced in extremely small quantity. We here
present a first experimental investigation of the rheological properties of the
pad secretion in the Colorado potato beetle {\it Leptinotarsa decemlineata}.
Because the secretion is produced in an extremely small amount at the level of
the terminal plate, we first develop a procedure based on capillary effects to
collect the secretion. We then manage to incorporate micrometric beads,
initially in the form of a dry powder, and record their thermal motion to
determine the mechanical properties of the surrounding medium. We achieve such
a quantitative measurement within the collected volume, much smaller than the
l sample volume usually required for this technique. Surprisingly,
the beetle secretion was found to behave as a purely viscous liquid, of high
viscosity. This suggests that no specific complex fluid behaviour is needed
during beetle locomotion. We build a scenario for the contact formation between
the spatula at the setal tip and a substrate, during the insect walk. We show
that the attachment dynamics of the insect pad computed from the high measured
viscosity is in good agreement with observed insect pace. We finally discuss
the consequences of the secretion viscosity on the insect adhesion
The influence of cytosolic phosphorylating glyceraldehyde 3-phosphate dehydrogenase (GAPC) on potato tuber metabolism
The aim of this work was to investigate the importance of cytosolic phosphorylating glyceralclehyde 3-phosphate dehydrogenase (GAPC) in potato carbohydrate metabolism. For this purpose, the cytosolic isoform of phosphorylating GAPC was cloned and used for an antisense approach to generate transgenic potato plants that exhibited constitutively decreased GAPDH activity. Potato lines with decreased activities of phosphorylating GAPC exhibited no major changes in either whole-plant or tuber morphology. However, the levels of 3-phosphoglycerate were decreased in leaves of the transformants. A broad metabolic phenotyping of tubers from the transformants revealed an increase in sucrose and UDPgiucose content, a decrease in the glycolytic intermediates 3-phosphoglycerate and phosphoenolpyruvate but little change in the levels of other metabolites. Moreover, the transformants displayed no differences in cold sweetening with respect to the wild type. Taken together these data suggest that phosphorylating GAPC plays only a minor role in the regulation of potato metabolism. The results presented here are discussed in relation to current models regarding primary metabolism in the potato tuber parenchyma
Wearing complete dental prostheses - Effects on perioral morphology
Background: To adequately perform rehabilitation of edentulous patients by a complete removable dental prosthesis (CRDP) is from basic interest to dentists to understand the morphologic changes caused by re-establishment
of a physiologic jaw relationship. Anthropometric analyses of standardized frontal view and profile photographs
may help elucidate such changes.
Material and Methods: Photographs of 31 edentulous patients were compared in relaxed lip closure and after insertion of a CRDP in stable occlusion. 2232 anthropometric distances were raised. Eighteen anthropometric indices
reflecting the perioral morphology and its integration in the vertical facial harmony were investigated.
Results: The intercanthal – mouth width index (
p
<.001), medial – lateral cutaneous upper lip height index (
p=
.007),
lower vermilion contour index (
p=
.022), vermilion – total upper lip height index (
p=
.018), cutaneous – total up
-
per lip height index (
p=
.023), upper lip – nose height index (
p=
.001), nose – upper face height index (
p=
.002),
chin – mandible height index (
p=
.013), upper lip – mandible height index (
p=
.045), nose – lower face height index
(
p=
.018), and nose - face height index (
p=
.029) showed significant pre- to post-treatment changes.
Conclusions: The investigated anthropometric indices presented reproducible results related to an increase in occlusal vertical dimension. Their application may be helpful in assessment, planning, and explanation of morphologic
effects of CRDPs on the perioral and overall facial morphology, which may helps to improve the aesthetic outcome
Differential Fiscal Performances of Plausible Disaster Events: A Storyline Approach for the Caribbean and Central American Governments under CCRIF
Fiscal resilience against disasters is vital for the recovery in the aftermath of climate hazards. Without swift access to available funds for disaster relief, damages to human and the economy would be further exacerbated. How insurance may influence fiscal performance over time and can increase fiscal resilience for today and under a future climate has not been looked at yet in detail. Focusing on the Caribbean region and on the fiscal performance of governments after disaster events, we empirically analyze the effectiveness of the Caribbean Catastrophe Risk Insurance Facility (CCRIF) regarding the reduction of short-term fiscal effects. We embed this analysis within a novel climate impact storyline approach where we produce past plausible events and investigate the usefulness of insurance under such events. The storylines were modified according to global and climate change related boundary conditions to address the issue whether the CCRIF is fit for purpose or will need to be adapted in the future. We found that both hurricane strikes and the CCRIF affect fiscal outcomes of Caribbean countries. Furthermore, there are indications that CCRIF can counteract the negative fiscal consequences over the short term period induced by the disaster. Our analysis should shed some light on the current discussions on how development related assistance can be structured to enhance climate resilience in highly exposed countries for both direct and fiscal impacts of disasters
\u3ci\u3eStaphylococcus aureus\u3c/i\u3e Metabolic Adaptations during the Transition from a Daptomycin Susceptibility Phenotype to a Daptomycin Nonsusceptibility Phenotype
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. The success of S. aureus as a pathogen is due in part to its many virulence determinants and resistance to antimicrobials. In particular, methicillin-resistant S. aureus has emerged as a major cause of infections and led to increased use of the antibiotics vancomycin and daptomycin, which has increased the isolation of vancomycin-intermediate S. aureus and daptomycin-nonsusceptible S. aureus strains. The most common mechanism by which S. aureus acquires intermediate resistance to antibiotics is by adapting its physiology and metabolism to permit growth in the presence of these antibiotics, a process known as adaptive resistance. To better understand the physiological and metabolic changes associated with adaptive resistance, six daptomycin-susceptible and -nonsusceptible isogenic strain pairs were examined for changes in growth, competitive fitness, and metabolic alterations. Interestingly, daptomycin nonsusceptibility coincides with a slightly delayed transition to the postexponential growth phase and alterations in metabolism. Specifically, daptomycin-nonsusceptible strains have decreased tricarboxylic acid cycle activity, which correlates with increased synthesis of pyrimidines and purines and increased carbon flow to pathways associated with wall teichoic acid and peptidoglycan biosynthesis. Importantly, these data provided an opportunity to alter the daptomycin nonsusceptibility phenotype by manipulating bacterial metabolism, a first step in developing compounds that target metabolic pathways that can be used in combination with daptomycin to reduce treatment failures
Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC
We present TeV gamma-ray observations of the Crab Nebula, the standard
reference source in ground-based gamma-ray astronomy, using data from the High
Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use
two independent energy-estimation methods that utilize extensive air shower
variables such as the core position, shower angle, and shower lateral energy
distribution. In contrast, the previously published HAWC energy spectrum
roughly estimated the shower energy with only the number of photomultipliers
triggered. This new methodology yields a much improved energy resolution over
the previous analysis and extends HAWC's ability to accurately measure
gamma-ray energies well beyond 100 TeV. The energy spectrum of the Crab Nebula
is well fit to a log parabola shape with emission up to at least 100 TeV. For the first
estimator, a ground parameter that utilizes fits to the lateral distribution
function to measure the charge density 40 meters from the shower axis, the
best-fit values are
=(2.350.04)10 (TeV cm
s), =2.790.02, and
=0.100.01. For the second estimator, a neural
network which uses the charge distribution in annuli around the core and other
variables, these values are
=(2.310.02)10 (TeV cm
s), =2.730.02, and
=0.060.010.02. The first set of uncertainties are statistical;
the second set are systematic. Both methods yield compatible results. These
measurements are the highest-energy observation of a gamma-ray source to date.Comment: published in Ap
Non-canonical Hedgehog signaling mediates profibrotic hematopoiesis-stroma crosstalk in myeloproliferative neoplasms.
The role of hematopoietic Hedgehog signaling in myeloproliferative neoplasms (MPNs) remains incompletely understood despite data suggesting that Hedgehog (Hh) pathway inhibitors have therapeutic activity in patients. We aim to systematically interrogate the role of canonical vs. non-canonical Hh signaling in MPNs. We show that Gli1 protein levels in patient peripheral blood mononuclear cells (PBMCs) mark fibrotic progression and that, in murine MPN models, absence of hematopoietic Gli1, but not Gli2 or Smo, significantly reduces MPN phenotype and fibrosis, indicating that GLI1 in the MPN clone can be activated in a non-canonical fashion. Additionally, we establish that hematopoietic Gli1 has a significant effect on stromal cells, mediated through a druggable MIF-CD74 axis. These data highlight the complex interplay between alterations in the MPN clone and activation of stromal cells and indicate that Gli1 represents a promising therapeutic target in MPNs, particularly that Hh signaling is dispensable for normal hematopoiesis
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