scholarly journals Broad lipid phase transitions in mammalian cell membranes measured by Laurdan fluorescence spectroscopy

2021 ◽  
Author(s):  
Nicolas Faerber ◽  
Christoph Westerhausen
Keyword(s):  
Fluorescence Spectroscopy ◽  
Lipid Membranes ◽  
Morphological Changes ◽  
Cholesterol Content ◽  
Lipid Phase ◽  
Generalized Polarization ◽  
Temperature Range ◽  
Membrane Order ◽  
Custom Made

Abstract Employing fluorescence spectroscopy and the membrane-embedded dye Laurdan we experimentally show broad order-disorder-transitions in membranes of various cell lines and red blood cell ghosts. A custom-made setup allows for the determination of fluorescence spectra and the determination of the generalized polarization (GP) as a measure for membrane order in the temperature range of -40°C to +90°C of µl-volumes of cell suspension. While artificial lipid membranes like phosphatidylcholine show sharp transitions as known from calorimetry measurements, living cells in a physiological temperature range do only show linear changes in generalized polarization. However, extending the temperature range shows the existence of broad transitions and their sensitivity to cholesterol content, pH and anaesthetic. Moreover, adaptation to culture conditions like decreased temperature and morphological changes like detachment of adherent cells or dendrite growth are accompanied by changes in membrane order as well. The observed GP changes are equivalent to temperature changes dT in the range of -12K < dT <+6K

scholarly journals Influence of Triphenyllead Chloride on Biological and Model Membranes

2000 ◽  
Vol 55 (9-10) ◽  
pp. 764-769
Author(s):  
Halina Kleszczyńska ◽  
Krzysztof Bielecki ◽  
Janusz Sarapuk ◽  
Anna Dziamska ◽  
Stanislaw Przestalski
Keyword(s):  
Lipid Membranes ◽  
Lemna Minor ◽  
Model Membranes ◽  
Lipid Phase ◽  
Experimental Conditions ◽  
Inhibition Of Growth ◽  
Model Lipid Membranes ◽  
Osmotic Stability ◽  
Spirodela Oligorrhiza

Abstract The physiological and hemolytic toxicities of triphenyllead chloride (TPhL) as well as its modyfying influence on model lipid membranes were studied. The experiments allowed the determination of TPhL concentrations causing 50% inhibition of growth of Spirodela oligorrhiza, Lemna minor and Solvinia natans (EC50), 100% hemolysis of pig erythrocytes (C100) and destabilization of planar lipid membranes (CC). Also, fluidity of erythrocyte ghosts was measured by fluorescence technique and osmotic sensitivity of erythrocytes to the presence of TPhL. All parameters studied were found to be dependent on pH, of experimental solutions and the concentration of TPhL. Acidic conditions increased EC50, C100 and CC concentrations of TPhL. Fluorescence and osmotic measurements showed that osmotic stability and fluidity decreased with increasing trimethyllead concentration. A possible mechanism of TPhL toxicity is discussed. It is assumed that TPhL is interacting with the lipid phase of the models used. It is also assumed that there may exist various, ionic and nonionic, forms of TPhL as a result of its speciation under different experimental conditions. These species, due to their differentiated lipophilicity, may exert different effects on the model membranes studied.

scholarly journals Using seed respiration as a tool for calculating optimal soaking times for ‘on-farm’ seed priming of barley (Hordeum vulgare)

2021 ◽  
pp. 1-9
Author(s):  
Javier Carrillo-Reche ◽  
Adrian C. Newton ◽  
Richard S. Quilliam
Keyword(s):  
Morphological Changes ◽  
Low Cost ◽  
Germination Rate ◽  
Seed Priming ◽  
Embryonic Axes ◽  
Seedling Vigour ◽  
Soaking Time ◽  
On Farm ◽  
Seed Respiration

Abstract A low-cost technique named ‘on-farm’ seed priming is increasingly being recognized as an effective approach to maximize crop establishment. It consists of anaerobically soaking seeds in water before sowing resulting in rapid and uniform germination, and enhanced seedling vigour. The extent of these benefits depends on the soaking time. The current determination of optimal soaking time by germination assays and mini-plot trials is resource-intensive, as it is species/genotype-specific. This study aimed to determine the potential of the seed respiration rate (an indicator of metabolic activity) and seed morphological changes during barley priming as predictors of the priming benefits and, thus, facilitate the determination of optimal soaking times. A series of germination tests revealed that the germination rate is mostly attributable to the rapid hydration of embryo tissues, as the highest gains in the germination rate occurred before the resumption of respiration. Germination uniformity, however, was not significantly improved until seeds were primed for at least 8 h, that is, after a first respiration burst was initiated. The maximum seedling vigour was attained when the priming was stopped just before the beginning of the differentiation of embryonic axes (20 h) after which vigour began to decrease (‘over-priming’). The onset of embryonic axis elongation was preceded by a second respiration burst, which can be used as a marker for priming optimization. Thus, monitoring of seed respiration provides a rapid and inexpensive alternative to the current practice. The method could be carried out by agricultural institutions to provide recommended optimal soaking times for the common barley varieties within a specific region.

Metabolic response to temperature stress in the Colombian freshwater crab Neostrengeria macropa (H. Milne Edwards, 1853) (Decapoda: Brachyura: Pseudothelphusidae)

2021 ◽  
Author(s):  
David M Hudson
Keyword(s):  
Metabolic Response ◽  
Infrastructure Development ◽  
Predator Prey ◽  
Temperature Range ◽  
Indicator Group ◽  
Response To Temperature ◽  
Performance Results ◽  
The City ◽  
The Ideal

Abstract Freshwater crustaceans are distributed throughout the montane and lowland areas of Colombia, and are therefore a useful indicator group for how aquatic species will respond to climate change. As such, metabolic determination of physiological performance was evaluated for the Colombian pseudothelphusid crab, Neostrengeria macropa (H. Milne Edwards, 1853), over a temperature range inclusive of current temperatures and those predicted by future scenarios in the plateau around the city of Bogotá, namely from 8 °C to 30 °C. The performance results mostly aligned with previous exploratory behavioral determination of the ideal temperature range in the same species, although the metabolism increased at the highest temperature treatments, a point when exploratory behavior declined. These results indicate that this species of montane crab behaviorally compensates for increased thermal stress by decreasing its physical activity, which could have negative predator-prey consequences with changes to community structure as different species undergo climate-mediated geographic range shifts in the region. As this species is endemic to the plateau surrounding Bogotá, it also experiences a number of other stressors to its survival, including infrastructure development and invasive species.

scholarly journals Fluorescence spectroscopy for the determination of reconstitution time of an in-vial lyophilised product

2021 ◽  
Vol 597 ◽  
pp. 120368
Author(s):  
Khaled ElKassas ◽  
Krishnakumar Chullipalliyalil ◽  
Michael McAuliffe ◽  
Sonja Vucen ◽  
Abina Crean
Keyword(s):  
Fluorescence Spectroscopy

Synchronous fluorescence spectroscopy for determination of tahini adulteration

Talanta ◽  
2017 ◽  
Vol 167 ◽  
pp. 557-562 ◽  
Author(s):  
Havva Tumay Temiz ◽  
Ugur Tamer ◽  
Aysel Berkkan ◽  
Ismail Hakki Boyaci
Keyword(s):  
Fluorescence Spectroscopy ◽  
Synchronous Fluorescence ◽  
Synchronous Fluorescence Spectroscopy
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