SciCombinator

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Concept: Egg white

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Recombinant protein overexpression of large proteins in bacteria often results in insoluble and misfolded proteins directed to inclusion bodies. We report the application of shear stress in micrometer-wide, thin fluid films to refold boiled hen egg white lysozyme, recombinant hen egg white lysozyme, and recombinant caveolin-1. Furthermore, the approach allowed refolding of a much larger protein, cAMP-dependent protein kinase A (PKA). The reported methods require only minutes, which is more than 100 times faster than conventional overnight dialysis. This rapid refolding technique could significantly shorten times, lower costs, and reduce waste streams associated with protein expression for a wide range of industrial and research applications.

Concepts: DNA, Gene, Signal transduction, Enzyme, Protein folding, Escherichia coli, Biotechnology, Egg white

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This paper investigates what “free-range” eggs are available for sale in supermarkets in Australia, what “free-range” means on product labelling, and what alternative “free-range” offers to cage production. The paper concludes that most of the “free-range” eggs currently available in supermarkets do not address animal welfare, environmental sustainability, and public health concerns but, rather, seek to drive down consumer expectations of what these issues mean by balancing them against commercial interests. This suits both supermarkets and egg producers because it does not challenge dominant industrial-scale egg production and the profits associated with it. A serious approach to free-range would confront these arrangements, and this means it may be impossible to truthfully label many of the “free-range” eggs currently available in the dominant supermarkets as free-range.

Concepts: Egg, Food, Chicken, Meat, Lutein, Factory farming, Egg white, Egg yolk

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The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils and of food chains. CLD may be transferred into eggs of hens reared outdoors, through polluted soil ingestion. Tropical volcanic soils display variable capacities of pollutant retention: CLD is less available and more persistent in andosol than in nitisol. The impact of soil type on CLD bioavailability to hens was tested through a relative bioavailability study. The deposition of CLD in egg yolk and in abdominal fat was measured in 42 individually housed laying hens fed with diets containing graded levels of CLD from polluted andosol, nitisol, or spiked oil during 23 days. Within each ingested matrix, the concentration of CLD in yolk and in abdominal fat linearly increased with the amount of ingested CLD (P < 0.001). However, the response to andosol diets and to nitisol diets was not different from the response to oil diets (P > 0.1), indicating that CLD was equally bioavailable to laying hens, irrespective of the matrix. This suggests that the hen’s gastrointestinal tract efficiently extracts CLD from the two tropical volcanic soils, regardless of their retention capacity. Thus, hens reared on polluted soils with CLD may lay contaminated eggs.

Concepts: Egg, Digestive system, Pollution, Chicken, Egg white, Egg yolk, Lecithin, Hen

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Eggs or egg-based foods, either raw or undercooked, have been identified as vehicles of Salmonella outbreaks. The low numbers of Salmonella organisms in eggs makes it difficult to detect them in frequency studies. The nested-PCR (n-PCR) technique shows more sensitivity and specificity than bacteriological culture methods (BCMs). A preenrichment method followed by enrichment and n-PCR is a good alternative for the investigation of Salmonella and Listeria monocytogenes in eggs. A total of 2,650 chicken eggs representing five commercial brands were purchased from 10 grocery stores. Ten eggs of each brand were combined in order to obtain 265 pooled samples (53 per brand). The shells and yolks of 100 pooled samples were analyzed for Salmonella, while the shells of 65 pooled samples were analyzed for L. monocytogenes, using BCM and a combined method of enrichment and n-PCR (CM-n-PCR). Sixteen eggshell pooled samples tested positive for Salmonella by CM-n-PCR, compared with only two by BCM. Three egg yolk pooled samples tested positive for this pathogen by CM-n-PCR; none tested positive by BCM. Three eggshell pooled samples tested positive for L. monocytogenes by CM-n-PCR and none by BCM. In Mexico, as in other countries, official methods for detection of Salmonella and L. monocytogenes in foods are based on standard bacteriological culture techniques. The inclusion of more sensitive methods such as the one used in the present investigation would increase the probability of detecting positive samples, particularly in those foods in which a very low number of cells is expected.

Concepts: Egg, Type I and type II errors, Sensitivity and specificity, Chicken, Lutein, Listeria monocytogenes, Egg white, Egg yolk

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The in vitro anti-denaturation and anti-hyaluronidase activities of Impatiens parviflora extracts and isolated galactolipids (MGDG-1, DGDG-1) were investigated. This is the first report on these compounds in I. parviflora. All extracts showed anti-hyaluronidase activity, but only methanolic extract from fresh leaves exhibited significant activity against heat-induced denaturation of BSA in a dose-dependent manner. At 500 μg/mL, the extract and the reference drug showed 79.05% and 99.81% inhibition of protein denaturation, respectively. These results indicate that fresh leaves of I. parviflora may be beneficial in inflammatory conditions, especially those associated with protein denaturation, such as rheumatoid arthritis. The study revealed that only MGDG-1 showed weak activity in anti-denaturation assay but both galactolipids were potent inhibitors of hyaluronidase. MGDG-1 completely inhibited the enzyme activity at the concentration of 127.9 μg/mL. These results indicate the potential of galactolipids in the treatment of diseases associated with the loss of hyaluronic acid.

Concepts: Protein, Enzyme, Protein folding, Rheumatoid arthritis, Enzyme inhibitor, Quaternary structure, Denaturation, Egg white

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Background: Protein in the diet is commonly ingested from whole foods that contain various macro- and micronutrients. However, the effect of consuming protein within its natural whole-food matrix on postprandial protein metabolism remains understudied in humans.Objective: We aimed to compare the whole-body and muscle protein metabolic responses after the consumption of whole eggs with egg whites during exercise recovery in young men.Design: In crossover trials, 10 resistance-trained men [aged 21 ± 1 y; 88 ± 3 kg; body fat: 16% ± 1% (means ± SEMs)] received primed continuous l-[ring-(2)H5]phenylalanine and l-[1-(13)C]leucine infusions and performed a single bout of resistance exercise. After exercise, participants consumed intrinsically l-[5,5,5-(2)H3]leucine-labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Repeated blood and muscle biopsy samples were collected to assess whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis.Results: Plasma appearance rates of protein-derived leucine were more rapid after the consumption of egg whites than after whole eggs (P = 0.01). Total plasma availability of leucine over the 300-min postprandial period was similar (P= 0.75) between the ingestion of whole eggs (68% ± 1%) and egg whites (66% ± 2%), with no difference in whole-body net leucine balance (P = 0.27). Both whole-egg and egg white conditions increased the phosphorylation of mammalian target of rapamycin complex 1, ribosomal protein S6 kinase 1, and eukaryotic translation initiation factor 4E-binding protein 1 during postexercise recovery (all P < 0.05). However, whole-egg ingestion increased the postexercise myofibrillar protein synthetic response to a greater extent than did the ingestion of egg whites (P= 0.04).Conclusions: We show that the ingestion of whole eggs immediately after resistance exercise resulted in greater stimulation of myofibrillar protein synthesis than did the ingestion of egg whites, despite being matched for protein content in young men. Our data indicate that the ingestion of nutrient- and protein-dense foods differentially stimulates muscle anabolism compared with protein-dense foods. This trial was registered at clinicaltrials.gov as NCT03117127.

Concepts: Protein, Metabolism, Nutrition, Ribosome, Egg, Muscle, Protein biosynthesis, Egg white

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Dietary lipids are one of the most effective stimulators of carotenoid absorption, but very limited data exist on the impact of endogenous food sources of lipids to enhance carotenoid absorption. The co-consumption of whole egg with carotenoid-rich foods may increase overall carotenoid absorption via lipid-rich egg yolk.

Concepts: Nutrition, Egg, Food, Lutein, Egg white, Egg yolk, Lecithin

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Few studies exist that have systematically examined the role of protein, and egg protein in particular, in appetite and energy intake regulation in children.

Concepts: Gene, Metabolism, Regulation, Digestion, Egg white, Breakfast, Contemporary R&B, TeenBeat Records

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For egg allergy, dietary avoidance is the only currently approved treatment. We evaluated oral immunotherapy using egg-white powder for the treatment of children with egg allergy.

Concepts: Egg, Food allergy, Egg white