From seafood waste to active seafood packaging: An emerging opportunity of the circular economy

Sustainable development is an overarching objective that requires an interdisciplinary approach in order to address the societal challenge concerning climate action, environment, resource efficiency and raw materials. In this context, valorization of abundant and available bio-wastes with high potential to manufacture value-added products is the first step to close the loop between waste and consumption in line with the main goal of the circular economy. In the last years, many research works have been published in the literature regarding novel food packaging. However, most of them are focused on packaging composition (scientific aspects) and some of them on the packaging manufacture (technological aspects), but very few studies are concerned about the influence of bringing novel food packaging systems into the market on environmental, social and economic issues. In this regard, this review intends to fill this gap, considering the potential of developing food packaging from food processing waste in order to create business for food industries, being aware of the food quality demanded by consumers and the environmental care demanded by institutions and society

Residues that affect activation and deactivation of cobalamin -dependent methionine synthase.

Cobalamin-dependent methionine synthase (MetH) is a 136 kDa monomeric enzyme that catalyzes methyl transfers from methyltetrahydrofolate to homocysteine to form methionine and tetrahydrofolate. This reaction is physiologically significant for two reasons: first, failure to methylate homocysteine to form methionine can lead to elevated homocysteine levels, which, in humans, is linked to cardiovascular disease and neural tube defects, and second, failure to demethylate methyltetrahydrofolate can lead to the folate pool becoming trapped in the methyl form, which can lead to deficiencies in other folate precursors that are essential for DNA synthesis and other processes. During primary turnover, the cobalamin prosthetic group of MetH cycles between the methylcobalamin and the cob(I)alamin forms. The cob(I)alamin form of the enzyme occasionally becomes oxidatively inactivated in a process termed deactivation. In order to return to the primary turnover cycle, the enzyme must undergo a reductive methylation using reduced flavodoxin and S-adenosylmethionine (AdoMet). The COO---terminal 38 kDa domain has been shown to be required for reductive methylation, and has been designated as the activation domain. To gain insight into the mechanism of activation, we identified several targets for mutagenesis in or near the activation domain, and constructed the mutant enzymes Gln893Gly, Pro1135Leu and Tyr1139Phe using a synthetic gene. We used these mutant enzymes to characterize the catalytic properties of the activation domain of MetH and elucidate the role that this domain plays in activation and deactivation. We have found that the mutant enzymes are impaired in activation and deactivation, and that the Pro1135Leu mutant enzyme binds AdoMet much more weakly than wild-type enzyme. We have shown that deactivation, like activation, is an enzyme-mediated oxidative process, and that oxygen is the physiological electron acceptor. The oxidatively inactivated enzyme is predominantly cob(III)alamin rather than cob(II)alamin in contrast to previous proposals. On the basis of these findings, we have proposed new mechanisms by which MetH undergoes activation and deactivation in the cell.Ph.D.BiochemistryBiological SciencesMolecular biologyPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132347/2/9963780.pd

SseJ Deacylase Activity by Salmonella enterica Serovar Typhimurium Promotes Virulence in Mice

Salmonella enterica serovar Typhimurium utilizes a type III secretion system (TTSS) encoded on Salmonella pathogenicity island-2 (SPI2) to promote intracellular replication during infection, but little is known about the molecular function of SPI2-translocated effectors and how they contribute to this process. SseJ is a SPI2 TTSS effector protein that is homologous to enzymes called glycerophospholipid-cholesterol acyltransferases and, following translocation, localizes to the Salmonella-containing vacuole and Salmonella-induced filaments. Full virulence requires SseJ, as sseJ null mutants exhibit decreased replication in cultured cells and host tissues. This work demonstrates that SseJ is an enzyme with deacylase activity in vitro and identifies three active-site residues. Catalytic SseJ mutants display wild-type translocation and subcellular localization but fail to complement the virulence defect of an sseJ null mutant. In contrast to the wild type, SseJ catalytic mutants fail to down regulate Salmonella-induced filament formation and fail to restore the sifA null mutant phenotype of loss of phagosomal membrane to sifA sseJ null double mutants, suggesting that wild-type SseJ modifies the vacuolar membrane. This is the first demonstration of an enzymatic activity for a SPI2 effector protein and provides support for the hypothesis that the deacylation of lipids on the Salmonella-containing vacuole membrane is important to bacterial pathogenesis

Neonatal Development of the Stratum Corneum pH Gradient: Localization and Mechanisms Leading to Emergence of Optimal Barrier Function

Although basal permeability barrier function is established at birth, the higher risk for infections, dermatitis, and percutaneous absorption of toxic agents may indicate incomplete permeability barrier maturation in the early neonatal period. Since stratum corneum (SC) acidification in adults is required for normal permeability barrier homeostasis, and lipid processing occurs via acidic pH dependent enzymes, we hypothesized that, in parallel with the less acidic surface pH, newborn SC would exhibit signs of incomplete barrier formation. Fluorescence lifetime imaging reveals that neonatal rat SC acidification first becomes evident by postnatal day 3, in extracellular "microdomains" at the SC- stratum granulosum (SG) interface, where pH-sensitive lipid processing is known to occur. This localized acidification correlated temporally with efficient processing of secreted lamellar body contents to mature extracellular lamellar bilayers. Since expression of the key acidifying mechanism NHE1 is maximal just prior to birth, and gradually declines over the first postnatal week, suboptimal SC acidification at birth cannot be attributed to insufficient NHE1 expression, but could instead reflect reduced NHE1 activity. Expression of the key lipid processing enzyme, beta-glucocerebrosidase (beta-GlcCer'ase), develops similar to NHE1, excluding a lack of beta-GlcCer'ase protein as rate limiting for efficient lipid processing. These results define a postnatal development consisting of initial acidification in the lower SC followed by outward progression, which is accompanied by formation of mature extracellular lamellar membranes. Thus, full barrier competence appears to require the extension of acidification in microdomains from the SC/SG interface outward toward the skin surface in the immediate postnatal period