Can membrane-bound carotenoid pigment zeaxanthin carry out a transmembrane proton transfer?

AbstractPolar carotenoid pigment zeaxanthin (β,β-carotene-3,3′-diol) incorporated into planar lipid membranes formed with diphytanoyl phosphatidylcholine increases the specific electric resistance of the membrane from ca. 4 to 13×107 Ω cm2 (at 5 mol% zeaxanthin with respect to lipid). Such an observation is consistent with the well known effect of polar carotenoids in decreasing fluidity and structural stabilization of lipid bilayers. Zeaxanthin incorporated into the lipid membrane at 1 mol% has very small effect on the overall membrane resistance but facilitates equilibration of the transmembrane proton gradient, as demonstrated with the application of the H+-sensitive antimony electrodes. Relatively low changes in the electrical potential suggest that the equilibration process may be associated with a symport/antiport activity or with a transmembrane transfer of the molecules of acid. UV–Vis linear dichroism analysis of multibilayer formed with the same lipid–carotenoid system shows that the transition dipole moment of the pigment molecules forms a mean angle of 21° with respect to the axis normal to the plane of the membrane. This means that zeaxanthin spans the membrane and tends to have its two hydroxyl groups anchored in the opposite polar zones of the membrane. Detailed FTIR analysis of β-carotene and zeaxanthin indicates that the polyene chain of carotenoids is able to form weak hydrogen bonds with water molecules. Possible molecular mechanisms responsible for proton transport by polyenes are discussed, including direct involvement of the polyene chain in proton transfer and indirect effect of the pigment on physical properties of the membrane

Exceptional molecular organization of canthaxanthin in lipid membranes

Canthaxanthin (β,β-carotene 4,4' dione) used widely as a drug or as a food and cosmetic colorant may have some undesirable effects on human health, caused mainly by the formation of crystals in the macula lutea membranes of the retina of an eye. Experiments show the exceptional molecular organization of canthaxanthin and a strong effect of this pigment on the physical properties of lipid membranes. The most striking difference between canthaxanthin and other macular pigments is that the effects of canthaxanthin at a molecular level are observed at much lower concentration of this pigment with respect to lipid (as low as 0.05 mol%). An analysis of the molecular interactions of canthaxanthin showed molecular mechanisms such as: strong van der Waals interactions between the canthaxanthin molecule and the acyl chains of lipids, restrictions to the segmental molecular motion of lipid molecules, modifications of the surface of the lipid membranes, effect on the membrane thermotropic properties and finally interactions based on the formation of the hydrogen bonds. Such interactions can lead to a destabilization of the membrane and loss of membrane compactness. In the case of the retinal vasculature, it can lead to an increase in the permeability of the retinal capillary walls and the development of retinopathy

Effect of Composition and Processing Conditions on Selected Properties of Potato-Based Pellets and Microwave-Expanded Snacks Supplemented with Fresh Beetroot Pulp

The aim of this study was to evaluate the influence of the addition of fresh beetroot pulp in amounts from 2.5 to 30.0 g/100 g, as well as variable screw speeds (60, 80, 100 rpm) on the chemical composition, water absorption, water solubility index, density, expansion rate, and texture of potato-based pellets and expanded snacks. Their protein and starch structure was analyzed using the Fourier-transformed infrared (FTIR) spectroscopy. The snack pellets were made at a moisture content of 33 g/100 g of blends using a single-screw extruder equipped with a plasticizing unit having a length-to-diameter ratio (L/D) of 18. Processing temperature ranged from 65 to 105°C. The ready-to-eat snacks were expanded using microwave treatment (750 W, 40 s). Fresh vegetable pulp addition raised the protein content. The extrusion-cooking caused an increase in the content of insoluble dietary fiber and water absorption index of the pellets. In contrast, the microwave treatment reduced values of these parameters in expanded products and decreased the insoluble dietary fiber content of the expanded snacks. The addition of fresh beetroot pulp diminished the expansion ability and increased the content of β-sheet proteins. Additionally, an increase in the content of β-turn and β-sheet protein fractions was observed at the expense of random coil structure. This indicates that the protein structure underwent some form of ordering as the molecular interactions of the proteins intensified. The highest fraction of β-structures and the smallest content of random coil were observed when 80 rpm was applied during processing. It seems to be the most efficient screw speed in processing fresh beetroot pulp-supplemented snack pellets. Application of a fresh beetroot pulp as an additive in microwave expanded snacks made it possible to obtain products with an increased amount of fiber and a reduced fat content as an attractive and healthy alternative to deep-fried snacks

Neural Modelling in the Exploration of the Biomethane Potential from Cattle Manure: A Case Study on Herds Structure from Wielkopolskie, Podlaskie, and Mazowieckie Voivodeships in Poland

In the presented study, data on the size and structure of cattle herds in Wielkopolskie, Podlaskie, and Mazowieckie voivodeships in 2019 were analyzed and subjected to modelling with the use of artificial intelligence, namely artificial neural networks (ANNs). The potential amount of biogas (m3) from cattle manure and slurry for the analyzed provinces was as follows: for the Mazowieckie Voivodeship, 800,654,186 m3; for the Podlaskie voivodeship, 662,655,274 m3; and for the Wielkopolskie voivodeship, 657,571,373 m3. Neural modelling was applied to find the relationship between the structure of the herds and the amount of generated slurry and manure (biomethane potential), as well as to indicate the most important animal types participating in biogas production. In each of the analyzed cases, the three-layer MLP perceptron with a single hidden layer proved to be the most optimal network structure. Sensitivity analysis of the generated models concerning herd structure showed a significant contribution of dairy cows to the methanogenic potential for both slurry and manure. The amount of slurry produced in the Mazowieckie and Wielkopolskie voivodeships was influenced in turn by heifers (both 6–12 and 12–18 months old) and bulls 12–24 months old, and in the Podlaskie voivodeship by calves and heifers 6–12 months old. As for manure, in addition to cows, bulls 12–24 months old and heifers 12–18 represented the main factor for Mazowieckie and Wielkopolskie voivodeships, and heifers (both 6–12 and 12–18 months old) for Podlaskie voivodeship

Application of a Selected Pseudorandom Number Generator for the Reliability of Farm Tractors

Knowledge of the use-to-failure periods of process equipment, including agricultural vehicles, is essential for the determination of their durability and reliability. Obtaining any empirical data on this issue is difficult and sometimes impossible. Experimental studies are costly and time-consuming. Manufacturers are usually reluctant to share such data, claiming that the information is classified for the sake of their companies. The purpose of this study was to compare empirical data with data generated using adequate statistical tools. The newly generated and very similar in value pseudorandom numbers were obtained by simulations using the Monte Carlo, Latin hypercube sampling and Iman-Conover methods. Reliability function graphs obtained from the generated time-series (use-to-failure periods) with matching Weibull distribution had very similar shape and scale parameters. They were are also comparable to parameters from experimental data extracted from a Polish Zetor agricultural tractor service station. The validation of the applied methods was limited as it was carried out only on the basis of the available data. Analysis of line graphs of cumulative deviations of the values of use-to-failure periods (times-to-fail) generated against empirical times-to-fail indicated that the best method in the studied case was the Monte Carlo method

Application of a Selected Pseudorandom Number Generator for the Reliability of Farm Tractors

Knowledge of the use-to-failure periods of process equipment, including agricultural vehicles, is essential for the determination of their durability and reliability. Obtaining any empirical data on this issue is difficult and sometimes impossible. Experimental studies are costly and time-consuming. Manufacturers are usually reluctant to share such data, claiming that the information is classified for the sake of their companies. The purpose of this study was to compare empirical data with data generated using adequate statistical tools. The newly generated and very similar in value pseudorandom numbers were obtained by simulations using the Monte Carlo, Latin hypercube sampling and Iman-Conover methods. Reliability function graphs obtained from the generated time-series (use-to-failure periods) with matching Weibull distribution had very similar shape and scale parameters. They were are also comparable to parameters from experimental data extracted from a Polish Zetor agricultural tractor service station. The validation of the applied methods was limited as it was carried out only on the basis of the available data. Analysis of line graphs of cumulative deviations of the values of use-to-failure periods (times-to-fail) generated against empirical times-to-fail indicated that the best method in the studied case was the Monte Carlo method

Laser Light Stimulation Effects on Scorzonera hispanica L. Seeds Germination, Field Emergence and Photosynthetic Pigments Content

The study presented herein concerns the effect of pre-sowing stimulation of scorzonera seeds with He–Ne laser on germination capacity, field emergence of seedlings and the content of chlorophylls and carotenoids. Seeds of scorzonera cv. ‘Duplex’, from harvests of various years, dis-played variable quality expressed by their germination capacity. They were subjected to pre-sowing stimulation with He–Ne laser light of the power of 40 mW and wavelength of 632.8 nm, surface power density of 5 mW·cm−2 and different exposure times. Germination capacity on Petri dish test increased only in one lot of seeds after exposure for 1 and 5 min. Increase in seedling emergence in the field experiment in the result of laser treatment occurred only in one seed lot. One-min laser treatment increased contents of chlorophylls and carotenoids in 8-day cotyledons (laboratory test) and in the second true leaves (field experiment)