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The aquaporin-based biomimetic thin-film composite membrane (ABM-TFC) has demonstrated superior separation performance and achieved successful commercialization. The larger-scale production of the ABM membrane requires an appropriate balance between the performance and manufacturing cost. This study has systematically investigated the effects of proteoliposome concentration, protein-to-lipid ratio, as well as the additive on the separation performance of ABM for the purpose of finding the optimal preparation conditions for the ABM from the perspective of industrial production. Although increasing the proteoliposome concentration or protein-to-lipid ratio within a certain range could significantly enhance the water permeability of ABMs by increasing the loading of aquaporins in the selective layer, the enhancement effect was marginal or even compromised beyond an optimal point. Alternatively, adding cholesterol in the proteoliposome could further enhance the water flux of the ABM membrane, with minor effects on the salt rejection. The optimized ABM not only achieved a nearly doubled water flux with unchanged salt rejection compared to the control, but also demonstrated satisfactory filtration stability within a wide range of operation temperatures. This study provides a practical strategy for the optimization of ABM-TFC membranes to fit within the scheme of industrial-scale production.

Abstract Larvae and early juveniles of fast-growing fish species show tremendous growth potential, leading to higher requirements for protein, high-unsaturated fatty acids, and other nutrients. Several commercial weaning diets with relatively high success have been developed for low/moderate-growing species; however, additional challenges are outlined to meet growth potential and energy requirements of such fast-growing species. The objective of the present study was to evaluate two commercial microdiets for marine fish, one having simultaneously a very high protein and high lipid contents (HIGH), and another (MOD) with a high protein and moderate lipid content, in a growth performance trial with greater amberjack post-larvae from 33 to 78 days after hatching. Moreover, histological preparations of liver, anterior and posterior intestine were assessed for hepatic and intestinal lipid inclusions quantification and gut epithelial brush height measurement. Activities of the digestive enzymes: pepsin, trypsin, chymotrypsin, lipase and amylase were also analyzed. Post-larvae fed HIGH microdiet exhibited higher final weight and lower feed conversion ratio that those fed on MOD microdiet. Liver displayed a higher level of lipid inclusions for the MOD diet than for HIGH diet. Moreover, enterocytes of posterior intestine presented a much higher level of supranuclear vacuoles for the HIGH diet compared to MOD diet. The lower Trypsin/Chymotrypsin ratio observed at the end of the experiment in larvae fed on MOD diet may indicate a deficiency in protein of this diet. Together, these results support that larvae of greater amberjack, and likely other fast-growing marine fish species, require high protein–high lipid microdiets. The use of microdiets developed targeting slower growing marine species may lead to sub-optimal performances in fast-growing larvae. Highlights • Post-larvae of greater amberjack show better growth performance when fed very high protein and high energy diet. • Post-larvae fed high protein: moderate energy diet present high liver steatosis. • No differences in brush border histology as well as in enzyme activities are observed between diet treatments. • A lower trypsin/chymotrypsin ratio when fed high protein: moderate energy diet may indicate a deficiency in protein. [ABSTRACT FROM AUTHOR]

Two 8-week trials, one in spring and the other in autumn-winter, were performed with sea bass fingerlings. After each growth period, pancreatic digestive enzyme synthesis in the pyloric caeca (PC), food anticipatory activity adaptation in the proximal intestine (PI) and nutrient absorption capacities in the distal intestine were measured at 24 h post-feeding. In spring, five isoenergetic diets with different protein levels (40, 45, 50, 55 and 59%) were formulated by simultaneously changing lipid and starch content. Animals fed the low-protein diets showed reduced accumulation of alkaline protease (40 to 50% diet), lipase (40 to 45% diet) and α-amylase (40 to 55% diet) in the PC; however, the activities of digestive enzymes in the PI were high in fish fed both low and high dietary protein diets, being significant for alkaline protease (40 and 59% diet) and α-amylase (40 and 45% diet). Zymography of the PC identified four proteases with trypsin-like activity (23, 22, 20 and 17 kDa) and an 18 kDa chymotrypsin activity that were modulated differentially according to diet. The PC/PI ratios were highest for alkaline protease and lowest for α-amylase, showing different patterns of response to changes in dietary composition: higher for protease on 45, 50 and 55% animals and α-amylase on 59% sea bass. l -Lys and d -Glc uptake capacities were down-regulated as dietary protein content declined, while no changes were found in l -Met and l -Trp. Based on the above-mentioned data and the optimum growth of animals fed with 50% protein, a protein-to-energy ratio study was performed. Sea bass were fed with five isoproteic (52%) diets that differed in dietary lipid content (12, 14, 16, 18 and 20%). Alkaline protease and lipase synthesis in the PC was up-regulated in low energy diets (12, 14 and 16% and 12 and 14%, respectively) and no changes were found in α-amylase. PC zymography was consistent with protease measurements. Only food anticipatory activity of lipase was up-regulated in animals fed 12% of lipid. l -Met and d -Glc were up-regulated by increasing dietary lipid and l -Lys and l -Trp were not modified. Dietary lipid content had no effect on final body weight. Finally, seasonal effects on alkaline protease synthesis in the PC were significantly higher in spring and animals showed higher growth in this season than in the autumn-winter. However, adaptation of food anticipatory activity in the PI was higher in autumn-winter. No differences were found in nutrient absorption capacities between seasons. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ghost of red blood cells can be converted to small lipid nanoparticles by using lysophopholipids. • From the ghost released proteins show molten globula. • In presence of membrane lipids elongated prolates (ellipsoids) are formed. • In absence of membrane lipids cylinder-like nanodiscs are formed. When the separated erythrocyte membranes (known as ghosts) are ultrasonicated, a significant part of the membrane proteins are released in the aqueous solvent, instead of being incorporated into the membranes of the formed nanoerythrosomes. In contrast to their membrane-bound counterparts, where helices and β-strands dominate, the released proteins show perturbed secondary structures with an increased ratio of helices, presumably participating in molten globules, as it has been revealed by circular dichroism (CD) and infra-red spectroscopy (IR). The shape and size of these proteins is diverse, and even their aggregates appear. When excess lipid (palmitoyl-lysophosphatidylcholine, LPC) is added to different ghost-derivatives (the full nanoerythrosome system, and its ultracentrifugation pellet and supernatant) in 2 × and 5 × lipid-to-protein mass ratio, various lipid nanoparticles are produced. The core–shell and nanodisc structural models obtained by small-angle X-ray scattering (SAXS) indicate that the choice of the precursor system has a more prominent effect on the resulting shape than the amount of lipid added: when starting from the protein-rich supernatant fraction, small (approx. 5 nm high and 7 nm wide) nanodisks are created. When lipid membranes are already present (in the pellet and the full nanoerythrosome fraction), similar LPC addition results in prolate ellipsoidal particles, with an aspect ratio between 3 and 5, and decreasing overall size when the amount of added lipid is increased. The ellipsoids formed from the total nanoerythrosome fraction are smaller than those from the ultracentrifugation pellet (longest axis around 15 vs 26 nm), whereas for higher LPC-to-protein ratio, the size in both cases reduce to nearly the same (13–14 nm) in both cases. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of varying dietary protein-to-lipid ratios (P/L) on growth performance and body composition of pike perch ( Sander lucioperca) fingerlings with an initial body weight of 1.35–1.40 g. Triplicate groups were reared during 56 days in recirculation systems and fed six experimental diets containing three dietary levels of lipid (90, 130, 170 g kg−1 of dry matter, d.m.) combined with two levels of dietary protein (470, 540 g kg−1 d.m.). During the experimental period the fixed feeding rates decreased from 10% to 5% of the total fish biomass per day. In contrast to previous results obtained with this species, the present study clearly demonstrated the occurrence of protein sparing effect. The best results for feed conversation ratio and specific growth rates were obtained in the treatments containing highest lipid level: diet 3 (P/L 47/17) and diet 6 (P/L 53/17). The d.m. and crude lipid contents of pike perch whole body increased in direct proportion of the dietary lipid levels. No difference was observed on crude protein and ash content among the treatments. Increasing hepatosomatic index at highest dietary lipid level suggested a limited lipid utilization of percids. [ABSTRACT FROM AUTHOR]

The aquaporin-based biomimetic thin-film composite membrane (ABM-TFC) has demonstrated superior separation performance and achieved successful commercialization. The larger-scale production of the ABM membrane requires an appropriate balance between the performance and manufacturing cost. This study has systematically investigated the effects of proteoliposome concentration, protein-to-lipid ratio, as well as the additive on the separation performance of ABM for the purpose of finding the optimal preparation conditions for the ABM from the perspective of industrial production. Although increasing the proteoliposome concentration or protein-to-lipid ratio within a certain range could significantly enhance the water permeability of ABMs by increasing the loading of aquaporins in the selective layer, the enhancement effect was marginal or even compromised beyond an optimal point. Alternatively, adding cholesterol in the proteoliposome could further enhance the water flux of the ABM membrane, with minor effects on the salt rejection. The optimized ABM not only achieved a nearly doubled water flux with unchanged salt rejection compared to the control, but also demonstrated satisfactory filtration stability within a wide range of operation temperatures. This study provides a practical strategy for the optimization of ABM-TFC membranes to fit within the scheme of industrial-scale production.