Natural vs synthetic auxin: Studies on the interactions between plant hormones and biological membrane lipids

2014 ◽  
Vol 133 ◽  
pp. 123-134 ◽  
Author(s):  
Michał Flasiński ◽  
Katarzyna Hąc-Wydro
Keyword(s):  
Plant Hormones ◽  
Membrane Lipids ◽  
Biological Membrane ◽  
Synthetic Auxin

Split Membrane Lipids and Polypeptides

1978 ◽  
Vol 36 (3) ◽  
pp. 521-532
Author(s):  
K.A. Fisher
Keyword(s):  
Electron Microscopy ◽  
Chemical Modification ◽  
Basic Property ◽  
Membrane Lipids ◽  
Biological Membrane ◽  
Independent Method ◽  
Functional Asymmetry ◽  
Probe Molecules ◽  
Membrane Asymmetry ◽  
Physical Methods

It is currently accepted that the biological membrane is composed of amphiphilie lipids arranged in bilayers with functionally important proteins embedded in, or spanning, the hydrophobic interior of the bilayer (Singer, 1977). Support for this view comes from a variety of chemical and physical methods. Enzymatic and chemical modification reactions have established the basic property of membrane asymmetry for lipids (Verkleij et al., 1973) and proteins (Steck, 1978) and the results of many physical studies are most easily interpreted in the context of structural and functional asymmetry. Such studies often rely on the modification of biomembranes by probes; relatively few methods exist, however, to study the transbilayer concentration of native molecules directly. Moreover, the accessibility of reagent or probe molecules to membrane molecules or domains, or their distribution within or across the plane of the membrane, remain in some instances uncertain. In such instances it is desirable to have the means to determine their location directly by an independent method such as electron microscopy.

scholarly journals Interaction between plant polyphenols and the erythrocyte membrane

2012 ◽  
Vol 17 (1) ◽  
Author(s):  
Sylwia Cyboran ◽  
Jan Oszmiański ◽  
Halina Kleszczyńska
Keyword(s):  
Sodium Chloride ◽  
Erythrocyte Membrane ◽  
Membrane Lipids ◽  
Biological Membrane ◽  
Optical Microscope ◽  
Lipid Monolayer ◽  
Osmotic Resistance ◽  
Plant Polyphenols ◽  
Hydrophilic Region ◽  
Osmotic Resistance Of Erythrocytes

AbstractThe purpose of these studies was to determine the effect of polyphenols contained in extracts from apple, strawberry and blackcurrant on the properties of the erythrocyte membrane, treated as a model of the biological membrane. To this end, the effect of the substances used on hemolysis, osmotic resistance and shape of erythrocytes, and on packing order in the hydrophilic region of the erythrocyte membrane was studied. The investigation was performed with spectrophotometric and fluorimetric methods, and using the optical microscope. The hemolytic studies have shown that the extracts do not induce hemolysis at the concentrations used. The results obtained from the spectrophotometric measurements of osmotic resistance of erythrocytes showed that the polyphenols contained in the extracts cause an increase in the resistance, rendering them less prone to hemolysis in hypotonic solutions of sodium chloride. The fluorimetric studies indicate that the used substances cause a decrease of packing order in the hydrophilic area of membrane lipids. The observations of erythrocyte shapes in a biological optical microscope have shown that, as a result of the substances’ action, the erythrocytes become mostly echinocytes, which means that the polyphenols of the extracts localize in the outer lipid monolayer of the erythrocyte membrane. The results obtained indicate that, in the concentration range used, the plant extracts are incorporated into the hydrophilic area of the membrane, modifying its properties.

The organization of cell surface membrane domains

1989 ◽  
Vol 47 ◽  
pp. 804-805
Author(s):  
Michael Edidin
Keyword(s):  
Cell Surface ◽  
Membrane Lipids ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Cell Types ◽  
Membrane Domains ◽  
Membrane Biology ◽  
Morphological Polarity ◽  
Discrete Domains ◽  
Membrane Components

Cell surface membranes are based on a fluid lipid bilayer and models of the membranes' organization have emphasised the possibilities for lateral motion of membrane lipids and proteins within the bilayer. Two recent trends in cell and membrane biology make us consider ways in which membrane organization works against its inherent fluidity, localizing both lipids and proteins into discrete domains. There is evidence for such domains, even in cells without obvious morphological polarity and organization [Table 1]. Cells that are morphologically polarised, for example epithelial cells, raise the issue of membrane domains in an accute form.The technique of fluorescence photobleaching and recovery, FPR, was developed to measure lateral diffusion of membrane components. It has also proven to be a powerful tool for the analysis of constraints to lateral mobility. FPR resolves several sorts of membrane domains, all on the micrometer scale, in several different cell types.

Melatonin reduces high levels of lipid peroxidation induced by potassium iodate in porcine thyroid

2019 ◽  
pp. 1-7 ◽  
Author(s):  
Paulina Iwan ◽  
Jan Stepniak ◽  
Malgorzata Karbownik-Lewinska
Keyword(s):  
Lipid Peroxidation ◽  
Oxidative Damage ◽  
Membrane Lipids ◽  
Chemical Properties ◽  
Iodine Concentration ◽  
Free Radical Scavenger ◽  
Radical Scavenger ◽  
Protective Effects ◽  
Potassium Iodate ◽  
Hormone Synthesis

Abstract. Iodine is essential for thyroid hormone synthesis. Under normal iodine supply, calculated physiological iodine concentration in the thyroid is approx. 9 mM. Either potassium iodide (KI) or potassium iodate (KIO3) are used in iodine prophylaxis. KI is confirmed as absolutely safe. KIO3 possesses chemical properties suggesting its potential toxicity. Melatonin (N-acetyl-5-methoxytryptamine) is an effective antioxidant and free radical scavenger. Study aims: to evaluate potential protective effects of melatonin against oxidative damage to membrane lipids (lipid peroxidation, LPO) induced by KI or KIO3 in porcine thyroid. Homogenates of twenty four (24) thyroids were incubated in presence of either KI or KIO3 without/with melatonin (5 mM). As melatonin was not effective against KI-induced LPO, in the next step only KIO3 was used. Homogenates were incubated in presence of KIO3 (200; 100; 50; 25; 20; 15; 10; 7.5; 5.0; 2.5; 1.25 mM) without/with melatonin or 17ß-estradiol. Five experiments were performed with different concentrations of melatonin (5.0; 2.5; 1.25; 1.0; 0.625 mM) and one with 17ß-estradiol (1.0 mM). Malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) concentration (LPO index) was measured spectrophotometrically. KIO3 increased LPO with the strongest damaging effect (MDA + 4-HDA level: ≈1.28 nmol/mg protein, p < 0.05) revealed at concentrations of around 15 mM, thus corresponding to physiological iodine concentrations in the thyroid. Melatonin reduced LPO (MDA + 4-HDA levels: from ≈0.97 to ≈0,76 and from ≈0,64 to ≈0,49 nmol/mg protein, p < 0.05) induced by KIO3 at concentrations of 10 mM or 7.5 mM. Conclusion: Melatonin can reduce very strong oxidative damage to membrane lipids caused by KIO3 used in doses resulting in physiological iodine concentrations in the thyroid.

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