1,865 research outputs found
Trapped ion mobility spectrometry and PASEF enable in-depth lipidomics from minimal sample amounts
A comprehensive characterization of the lipidome from limited starting material remains very challenging. Here we report a high-sensitivity lipidomics workflow based on nanoflow liquid chromatography and trapped ion mobility spectrometry (TIMS). Taking advantage of parallel accumulation-serial fragmentation (PASEF), we fragment on average 15 precursors in each of 100 ms TIMS scans, while maintaining the full mobility resolution of co-eluting isomers. The acquisition speed of over 100 Hz allows us to obtain MS/MS spectra of the vast majority of isotope patterns. Analyzing 1 mu L of human plasma, PASEF increases the number of identified lipids more than three times over standard TIMS-MS/MS, achieving attomole sensitivity. Building on high intra- and inter-laboratory precision and accuracy of TIMS collisional cross sections (CCS), we compile 1856 lipid CCS values from plasma, liver and cancer cells. Our study establishes PASEF in lipid analysis and paves the way for sensitive, ion mobility-enhanced lipidomics in four dimensions
Textural and Microstructural Properties of Frozen Fish Mince as Affected by the Addition of Nonfish Proteins and Sorbitol
Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils.
The mechanisms of reducing texture hardening appear to be different between sorbitol and nonfish proteins. Water binding properties and dispersibility made the difference among nonfish proteins in reducing freeze-contraction of myofibrils. Nonfish proteins not only reduced texture hardening during frozen storage, but also modified texture during cooki ng as they underwent thermal gelation specific to each protein used
Cut mowing and grazing effects with grey cattle on plant species composition in case of Pannon wet grasslands
Examined area can be found at Balaton Uplands National Park (Hungary). 5 sample areas were
examined in Badacsonytördemic: 1: 32 hectare under-grazed pasture, 2: 38 hectare overgrazed pasture, 3:
34 hectare hayfield, 4: trampled area, 5: beaten track. Livestock population was 118 in the monitored
pastures. Sampling was executed along five 52m long circular transects, within 5cm Ă 5cm interlocking
quadrates. Based on the data we can state that the curve of the drinking area was the highest of speciesarea
examinations however weed appeared because of degradation which provided more species.
According to species-area examinations overgrazed areas were richer in species then other examined
areas. Based on diversity data drinking area considered degraded, while meadow and overgrazed areas
was considered as proper state. Diversity of meadow was larger, but dominance of economically useful
species was smaller. The amount of less valuable species â Carex hirta â increased
A new life for sterile neutrino dark matter after the pandemic
We propose a novel mechanism to generate sterile neutrinos in the early Universe, by converting ordinary neutrinos in scattering processes . After initial production by oscillations, this leads to an exponential growth in the abundance. We show that such a production regime naturally occurs for self-interacting , and that this opens up significant new parameter space where make up all of the observed dark matter. Our results provide strong motivation to further push the sensitivity of X-ray line searches, and to improve on constraints from structure formation
Collective and single cell behavior in epithelial contact inhibition
Control of cell proliferation is a fundamental aspect of tissue physiology
central to morphogenesis, wound healing and cancer. Although many of the
molecular genetic factors are now known, the system level regulation of growth
is still poorly understood. A simple form of inhibition of cell proliferation
is encountered in vitro in normally differentiating epithelial cell cultures
and is known as "contact inhibition". The study presented here provides a
quantitative characterization of contact inhibition dynamics on tissue-wide and
single cell levels. Using long-term tracking of cultured MDCK cells we
demonstrate that inhibition of cell division in a confluent monolayer follows
inhibition of cell motility and sets in when mechanical constraint on local
expansion causes divisions to reduce cell area. We quantify cell motility and
cell cycle statistics in the low density confluent regime and their change
across the transition to epithelial morphology which occurs with increasing
cell density. We then study the dynamics of cell area distribution arising
through reductive division, determine the average mitotic rate as a function of
cell size and demonstrate that complete arrest of mitosis occurs when cell area
falls below a critical value. We also present a simple computational model of
growth mechanics which captures all aspects of the observed behavior. Our
measurements and analysis show that contact inhibition is a consequence of
mechanical interaction and constraint rather than interfacial contact alone,
and define quantitative phenotypes that can guide future studies of molecular
mechanisms underlying contact inhibition
Change of composition and diversity of species and grassland management between different grazing intensity in Pannonian dry and wet grasslands
Investigations were carried out in wet and dry pasture. Coenological recordings were taken in
three zones. The first zone (âAâ) located 0-50 m near the stable, second zone (âBâ) located 50-150 m
from the stable, while the third zone (âCâ) located farther than 150 m. We have carried out analyses of
ecological and environmental factors and life form types. Based on our results for both dry and wet
grasslands, quadrates of âAâ zone were well isolated from the rest of the zones. Overgrazing, which
involves considerable trampling, vanishes differences among vegetations, thereby promotes weed and
disturbance tolerant rich vegetation. The lowest species number and diversity could be found here. Due to
the nitrogen enrichment due to the constant presence of livestock, drier and less heat demanding habitat
developed in the âAâ zones, according to the environmental indicators. Because of the change in
management, conservation and diversity values of âCâ zone increased, however, according to nature
protection values it underperformed compared to âBâ zone. According to the sample area, wet grasslands
from the sandy areas of KiskunsĂĄg, preserve nature protection values and grass composition better
moving away from stables, due to less grazing pressure. Drier backgrounds tolerate stronger grazing
pressure
Incorporating chemical signalling factors into cell-based models of growing epithelial tissues
In this paper we present a comprehensive computational framework within which the effects of chemical signalling factors on growing epithelial tissues can be studied. The method incorporates a vertex-based cell model, in conjunction with a solver for the governing chemical equations. The vertex model provides a natural mesh for the finite element method (FEM), with node movements determined by force laws. The arbitrary LagrangianâEulerian formulation is adopted to account for domain movement between iterations. The effects of cell proliferation and junctional rearrangements on the mesh are also examined. By implementing refinements of the mesh we show that the finite element (FE) approximation converges towards an accurate numerical solution. The potential utility of the system is demonstrated in the context of Decapentaplegic (Dpp), a morphogen which plays a crucial role in development of the Drosophila imaginal wing disc. Despite the presence of a Dpp gradient, growth is uniform across the wing disc. We make the growth rate of cells dependent on Dpp concentration and show that the number of proliferation events increases in regions of high concentration. This allows hypotheses regarding mechanisms of growth control to be rigorously tested. The method we describe may be adapted to a range of potential application areas, and to other cell-based models with designated node movements, to accurately probe the role of morphogens in epithelial tissues
The role of caretakers in disease dynamics
One of the key challenges in modeling the dynamics of contagion phenomena is
to understand how the structure of social interactions shapes the time course
of a disease. Complex network theory has provided significant advances in this
context. However, awareness of an epidemic in a population typically yields
behavioral changes that correspond to changes in the network structure on which
the disease evolves. This feedback mechanism has not been investigated in
depth. For example, one would intuitively expect susceptible individuals to
avoid other infecteds. However, doctors treating patients or parents tending
sick children may also increase the amount of contact made with an infecteds,
in an effort to speed up recovery but also exposing themselves to higher risks
of infection. We study the role of these caretaker links in an adaptive network
models where individuals react to a disease by increasing or decreasing the
amount of contact they make with infected individuals. We find that pure
avoidance, with only few caretaker links, is the best strategy for curtailing
an SIS disease in networks that possess a large topological variability. In
more homogeneous networks, disease prevalence is decreased for low
concentrations of caretakers whereas a high prevalence emerges if caretaker
concentration passes a well defined critical value.Comment: 8 pages, 9 figure
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