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This study compares growth, intake and retention efficiencies of nutrients and energy between common sole ( Solea solea L.) fed ragworm ( Nereis virens, Sars), blue mussel ( Mytilus edulis L.) and an artificial (commercial) feed. Food types were fed to common sole (mean initial body weight: 44.9 ± 2.3 g) in excess three times a day over a 54-day-period. The growth rate in common sole fed the natural prey (8.5 g kg−0.8 d−1) was significantly higher compared to the growth rate in fish fed the artificial feed (5.1 g kg−0.8 d−1). Nutrient and energy intake was significantly lower in common sole fed the artificial feed than in fish fed natural prey. The only exception was fat intake which was higher in common sole fed the artificial feed in contrast to fish fed the natural prey. Nutrient and energy retention efficiencies were significantly lower in common sole fed the artificial feed than in fish fed the natural prey. In conclusion, the low growth in common sole fed the artificial feed was related to lower nutrient and energy intake as well as lower nutrient and energy retention efficiencies. It is suggested that reduced intake of the artificial feed might be related to the high dietary fat content of the artificial feed. [ABSTRACT FROM AUTHOR] more...

To enhance the biocompatibility or extend the biomedical application of poly(caprolactone) (PCL), protein retention on PCL surface is often required. In this study, poly(acrylamide) (PAAm) brushes were grown from PCL surface via surface-initiated atom transfer radical polymerization (SI-ATRP) and served as a protein-capturing platform. Grafted PAAm was densely packed on surface and exhibited superior protein retention ability. Captured protein was found to be resistant to washing under detergent environment. Furthermore, protein structure after being captured was investigated by circular dichroism (CD) spectroscopy, and the CD spectra verified that secondary structure of captured proteins was maintained, indicating no denaturation of protein happened for retention process. [ABSTRACT FROM AUTHOR] more...

The suitability of land animal by-products (ABPs) in feed for Atlantic salmon postsmolts (initial weight 372 g) in sea water was studied in a feeding experiment, using poultry by-product meal (PBM) and porcine blood meal (BM) as protein sources and poultry oil as fat source. Four extruded feeds were tested in a 2 * 2 factorial model, with or without ABP protein sources and with or without poultry oil. The control feed contained a mix of marine and plant ingredients. Initial feed intake was highest in the ABP protein-based diets, whereas poultry oil had a weak opposite effect. No differences were seen in growth rate or body weight. Addition of PBM and BM led to increased FCR, and lower retention of crude protein and energy. This could be explained by lower digestibility of amino acids and crude protein, and a slightly lower energy level in these diets. Reduced igf1 mRNA levels in liver and muscle were seen in fish fed dietary ABP protein and oil. Despite lower protein digestibility of ABP protein, this study confirms the suitability of ABP protein and lipid in combination with plant ingredients in feed for Atlantic salmon growers. [ABSTRACT FROM AUTHOR] more...

A factorial experiment was conducted with black tiger shrimp ( Penaeus monodon ) juveniles to determine the effects of varying protein inclusion in the diet and also varying inclusion of a microbial biomass on growth, feed and nutrient utilization when fed in indoor laboratory conditions. The growth performance of the shrimp improved with increasing diet protein level. However, in the absence of the added microbial biomass, this growth performance plateaued at the 480 g/kg protein level. The addition of the microbial biomass improved growth at each inclusion level of both protein and microbial biomass. No plateau in growth was observed with the addition of the microbial biomass. Improvements in feed conversion were seen with increasing dietary protein levels and also the inclusion of the microbial biomass. Examination of the feed intake of each treatment supports that there was a combined effect of an increase in feed intake and improvements in feed conversion that contributed to the improvements in growth performance with the use of the microbial biomass, but the increases in dietary protein level largely influenced growth through improvements in feed conversion. [ABSTRACT FROM AUTHOR] more...

The present study evaluates the effect of dietary glutamate and glutamine supplementation on growth performance, body composition and expression of key enzymes involved in the hepatic metabolism of juvenile gilthead seabream ( Sparus aurata ). Fish were fed for 52 days with four diets, which were identical in composition except for a 4% supplementation with glutamate (GLU diet), glutamine (GLN diet), carbohydrate (CHO diet) or bovine serum albumin (BSA diet). Glutamate and glutamine supplementation improved feed conversion ratio and protein retention compared to carbohydrate supplementation, and, in the case of glutamate, protein retention was improved over that of fish fed the protein supplemented diet. Feeding CHO and GLU diets resulted in up-regulation of glucokinase and lipogenic enzymes compared to fish fed GLN and BSA diets. Consistently, fish fed CHO or GLU diets showed higher triglyceride levels in serum and liver, and feeding the GLU diet resulted in higher body fat content than in fish fed GLN or BSA diets. The liver of fish fed GLN or BSA diets showed increased glutamate dehydrogenase activity in the direction of the glutamate oxidation. In contrast to fish fed the BSA diet, increased glutamate oxidation did not reduce free glutamine and glutamate levels in the liver of fish fed the GLN diet, suggesting that glutamine intake exceeded liver's energy requirements. In conclusion, glutamate supplementation improved hepatic glucose metabolism, whereas supplemented glutamine seems to be preferentially oxidized over amino acids derived from dietary protein, thus promoting higher protein retention in both cases. Our findings indicate that glutamate and glutamine could partly replace dietary protein and that glutamate supplementation could also facilitate protein replacement by carbohydrates in fish feeds. [ABSTRACT FROM AUTHOR] more...

Fish appear to have a limited capacity for digesting complex proteins during the early life stages. A better understanding of fish larvae protein digestive capacity and subsequent metabolic utilisation (amino acid (AA) catabolism and retention), depending on dietary protein molecular weight (MW) and larval development stages, is essential for developing formulated microdiets suited to larval requirements throughout ontogeny. The aim of this work was to develop a method enabling the in vivo production of radiolabelled polypeptides and protein fractions of different MW using Artemia metanauplii , and apply this new tool to assess protein digestive capacity and evaluate protein metabolic utilisation (catabolism and retention) throughout ontogeny of Senegalese sole larvae. Characterisation of MW distribution of Artemia protein content by size exclusion chromatography at different time points after hatching showed that from hatching to 24 h post-hatching (hph), the profile is dominated by polypeptides and proteins having a MW in the ranges 0.5–1.9 kDa, 2.8–7.0 kDa and above 476 kDa. At 36 hph a shift from high MW proteins to lower MW polypeptides was observed in the elution patterns. Fractions of radiolabelled polypeptides and proteins of various MW were produced through in vivo labelling of A. metanauplii , by incubation in a [U– 14 C] free AA mixture, and subsequent separation of Artemia proteins according to their MW by size exclusion chromatography. Digestibility and metabolic utilisation of some of the radiolabelled polypeptide fractions obtained (fractions of 1.0 kDa and 6.8 kDa) were assessed throughout Senegalese sole larval development (12, 21 and 34 days after hatching (DAH)) fed on live feed, through the controlled tube-feeding methodology combined with metabolic chambers. The results showed that the polypeptide fraction of 1.0 kDa was highly digestible and similarly retained in larval body at all developmental stages assayed. Conversely, the 6.8 kDa polypeptide fraction was poorly absorbed by young larval stages (12 DAH) but absorption improved throughout larval development (from 12 to 34 DAH). Body retention efficiency of the 6.8 kDa polypeptide fraction tended also to increase (and catabolism rate tended to decrease) throughout ontogeny, displaying a positive correlation (Spearman's correlation) with larval age. The method we report here is novel and may constitute a useful tool to assist in defining the most suitable MW range of proteins to incorporate into larval diets, for different developmental stages of Senegalese sole and other teleost larvae. [ABSTRACT FROM AUTHOR] more...

A 9-week feeding trial was carried out to evaluate dietary arginine requirement of juvenile red sea bream. Six isonitrogenous and isocaloric diets (50% crude protein and 17.7 kJ g − 1 gross energy) were formulated to contain graded levels of arginine including 1.42, 1.88, 2.22, 2.54, 3.08 and 3.43% of diet (2.84–6.86% of dietary protein), and fed triplicate groups of fish (13.3 ± 0.2 g) to apparent satiation twice daily. At the end of the feeding trial, fish fed ≥ 2.22% arginine showed significantly ( P < 0.05) higher growth than those fed 1.42% arginine. Significant improvement in protein productive value was found at dietary arginine level of 2.54% compared to the fish fed 1.42% arginine. Significant reductions in whole-body and muscle lipid contents were found by increment of arginine level and whole-body protein increased significantly in fish fed 2.22–2.54% arginine compared to those fed 1.42% arginine. Plasma total protein level significantly was increased in fish fed 2.54–3.08% arginine, and alanine aminotransferase activity and glucose level were significantly decreased in fish fed 2.22–2.54% and ≥ 1.88% arginine, respectively, compared to the group fed 1.42% arginine. Significant improvements in lysozyme and myeloperoxidase activities and total immunoglobulin level were obtained by dietary arginine increment. Also, significantly higher total nitric oxide synthase activity was recorded at 3.08% arginine level in comparison to 1.42% arginine. A broken-line regression analysis on weight gain showed that the optimum dietary arginine level is 2.37% of diet (4.74% of dietary protein). [ABSTRACT FROM AUTHOR] more...

Amino acids are vital for all living organisms including fish and histidine is an essential amino acid for fish. In view of this, dietary histidine requirement of fry Heteropneustes fossilis was determined by feeding casein-gelatin-based isonitrogenous (430 g kg−1 CP) and isocaloric (17.9 MJ kg−1 GE; 15.5 MJ kg−1 DE) amino acid test diets (10 to 20 g histidine kg−1 dry diet) to quadruplicate groups of randomly assigned fish to apparent satiety for 12 weeks. Maximum absolute weight gain (AWG; 44 g fish−1), protein retention efficiency (PRE; 20%), protein efficiency ratio (PER; 1.04), haemoglobin (Hb; 11.24 g dL−1), haematocrit (Hct; 35.11%), red blood count (RBCs; 2.98 × 109 mL−1) and lowest erythrocyte sedimentation rate (ESR; 1.92 mm h−1) were obtained at 16 g histidine kg−1 dry diet. The 95% maximum quadratic response of above data exhibited the requirement to be at 15.2, 15.1, 15.6 and 15.5 g histidine kg−1 diet. As histidine is found in higher concentration in haemoglobin, requirement obtained for Hct% and Hb is 4% greater than that required for maximizing weight gain and protein retention. Based on these results, dietary histidine requirement of H. fossilis fry is recommended between 15.1 and 15.6 g kg−1, corresponding to 35.1-36.3 g kg−1 protein. [ABSTRACT FROM AUTHOR] more...

The objectives of this study were to further optimize balance of dietary amino acids (AA) offered to Nile tilapia by investigating the role of dispensable AA (DAA) across the range of indispensable AA (IAA) intakes. The possible limitation of IAA intake in fish consuming diets with high inclusion of crystalline AA (CAA) supplemented to the diets was also confirmed. The basal diet was formulated to contain 22.2% intact protein in which IAA were adjusted to reach 100%, 110% and 120% of NRC requirements with or without DAA supplementation. Glycine and glutamic acid were used as DAA sources at 1:1 and 2:2 ratio to assign 2 levels of DAA at 2% and 4% of the diet. Fish were hand sorted to a uniform size then randomly stocked into 44 aquaria with 15 fish per/tank. Fish were fed 4 times a day to near satiation over a 10-week period. To evaluate feeding regimes on CAA utilization diets with 100% IAA without DAA supplements and 110% IAA with 4% DAA supplements were paired and fed to fish using 2 and 4 feedings per day. Results confirmed that DAA contribute to meeting the nitrogen requirement of fish in which fish fed diets with DAA supplementation had significantly higher growth rates (thermal-unit growth coefficient, TGC) and lower FCR compared to fish fed diets without DAA supplementation. Growth of fish fed diets without DAA supplementation was not comparable to fish fed diets supplemented with DAA irrespective of IAA supplements up to 120% NRC requirement. Fish fed diets with DAA supplements at 4% exhibited superior growth compared to fish fed diets with 0% and 2% DAA supplements. The supplementation of IAA at 110% NRC requirement helped the fish have better growth compared to fish fed diets formulated to 100% NRC. However, no further benefit was observed on growth performance of fish fed diets with IAA supplements up to 120%. Fish fed diets with IAA supplements at 110% NRC and 4% DAA supplements exhibited the best response. The results of this study indicated that although DAA provided benefits in balancing AA profiles of feed, limitation of IAA intake at 100% NRC might cause impaired growth of Nile tilapia. In addition to this, no influence of feeding frequency was obtained on growth performance of fish feed, suggesting that fish can be fed successfully two times per day regardless of high inclusion levels of CAA. • The important role of DAA in meeting the nitrogen requirement of Nile tilapia is confirmed in which DAA inclusion rate of 4% of the diet offering the best performance of fish. • The result of this study also indicates the inferior growth of fish fed diet with IAA supplements at 100% NRC requirements which might result from limitation of daily IAA intake. • Fish can be fed successfully two times per day regardless of high inclusion levels of crystalline amino acid. [ABSTRACT FROM AUTHOR] more...

The lack of specific compound diets for cephalopods is limiting the industrial development of some species. In this study, four agglutinated moist diets were tested in individually reared Octopus vulgaris (979 ± 151 g) for 8 weeks. All diets were based on bogue Boops boops, accidentally reared in fish farms (aquaculture by-product), and agglutinated with alginate and calcium. One diet was based exclusively on bogue fillets, two on bogue fillets complemented with meat from two crab species ( Portunus pelagicus, Grapsus grapsus) and the last one on bogue and G. grapsus meals. As a control diet, bogue and P. pelagicus were supplied fresh on alternate days. All diets induced similar feed intake (2.1-2.6% day−1). However, the meal-based diet induced negative growth in comparison with the control and the other agglutinated diets (0.80-0.85% day−1). Higher lipid content in agglutinated diets (28-30% dw) in comparison with the control diet (16% dw) led to higher protein retention in muscle. These results underline the inadequacy of traditional meals in diets for cephalopods and that the inclusion of crab meat did not increase feeding rates and growth in O. vulgaris. The dietary fatty acid, with high levels of oleic and linoleic acid and low levels of ARA, clearly reflected in digestive gland, while only decreasing ARA and increasing EPA levels were observed in muscle, with no apparent negative effect on growth. [ABSTRACT FROM AUTHOR] more...

Two slaughter experiments were carried out to evaluate the growth, content and deposition of tissues and the protein and energy retention in the meat of the carcass in growing broiler fed with canola meal (CANM) in substitution of soybean meal (SOYM). In Exp 1, six male broilers, 43 d of age, were slaughtered at the beginning and 36 broilers were assigned to three diets with increasing amounts of CANM (0, 10 and 20 %) combined with two levels of digestible lysine (DL: 0.85 y 0.95 %). In Exp 2, six female and six male broilers, 28 d of age, were slaughtered at the beginning and 72 broilers were assigned, within sex, to two diets (SOYM or CANM as unique protein source) combined with three energy levels (3.0, 3.1 and 3.2 Mcal of ME/kg of feed). Each experiment lasted two weeks and at the end all birds were sacrificed. In Exp 1, there were not statistical differences in the productivity or the protein and energy retention in the carcass among CANM levels (P>0.05). In Exp 2, the feed, protein and energy intake and the fat deposition were greater (P<0.05) with SOYM, but the weight gain, feed efficiency and the protein and energy retention in the carcass were similar among diets. The results indicate that is feasible to partial- or totally substitute the soybean meal by canola meal in the diets of grower broiler chickens. [ABSTRACT FROM AUTHOR] more...

Two experiments were done to evaluate the effects of poultry meal (PM), meat meal (MM) or solvent-extracted soybean meal (SBM) inclusion on the performance of Australian snapper Pagrus auratus. In each experiment, test feeds were formulated with similar contents of digestible protein (DP) and digestible energy (DE) using previously determined digestibility coefficients for this species. In experiment 1, groups of snapper (initial weight 14 g) were fed 4 feeds containing 360, 480, 610 or 730 g kg PM; 3 feeds containing 345, 320 or 500 g kg MM; 3 feeds containing 420, 600 or 780 g kg SBM. In experiment 2, groups of snapper (initial weight 87 g) were fed 3 extruded test feeds that contained combinations of PM, MM, SBM or blood meal (BM) which replaced all but 600, 250 or 160 g kg of fishmeal in respective diet formulations. Both experiments included a proprietary extruded aquafeed (COM) to benchmark fish performance. In experiment 1, weight gain was highest in snapper fed feeds containing 360, 345 or 420 g kg of PM, MM or SBM, respectively, and was similar ( P > 0.05) to snapper fed the COM feed. Nonetheless, weight gain and protein retention efficiency tended to decrease as the amount of each test ingredient was increased. Relative feed intake was not affected by the inclusion level of PM, MM or BM, but declined significantly in snapper fed diets containing 600 or 780 g kg SBM. Feeding behaviour indicated fish found these feeds unpalatable. In experiment 2, the harvest weight of snapper fed the 3 extruded test feeds was similar ( P > 0.05), but lower than snapper fed the COM feed (i.e. 234 vs. 256 g). Feed conversion ratio (FCR) was best in snapper fed the COM feed (FCR = 1.53); however, the FCR of snapper fed feeds containing 160 (FCR = 1.66), 250 (FCR = 1.70) or 600 g kg fishmeal (FCR = 1.60) was not different ( P > 0.05). Australian snapper will readily accept feeds containing high levels of PM, MM or SBM and feeds containing these ingredients will support rapid weight and protein gain with little affect on whole body composition. In combination, these feed ingredients were able to replace all but 160 g kg of fishmeal in an extruded test feed. As such, they serve as valuable alternatives to fishmeal and extend the manufacturing options available to aquafeed producers. [ABSTRACT FROM AUTHOR] more...

Twelve 4-week-old male Wistar rats weighing 100 g were fed diets semi-ad libitum for 22 d containing either 1.5% conjugated linoleic acid (CLA-diet) or high oleic sunflower oil (Control-diet). The CLA was structured triacylglycerol with predominantly cis-9, trans-11 and trans-10, cis-12 fatty acid isomers in the inner position and oleic acid in the other positions of the glycerol molecule. The rats were kept individually in metabolic cages. From days 8-16 energy, nitrogen (N) and carbon (C) balances as well as gas exchange measurements in open-air circuit respiration chambers were performed. CLA had no significant influence on feed intake, daily gain in weight or feed conversion efficiency, but the digestibility of nutrients and energy was significantly reduced (except for fat). CLA did not affect N-balance, but reduced the level of daily retained fat (RQ-method: 0.107 vs. 0.417 g/d, p < 0.01) and consequently energy retention in fat. This was explained by increased heat production (HP, RQ-method: 224.6 vs. 214.6 kJ/d, p < 0.001) caused by a higher fat oxidation (28.9% vs. 22.3%, p < 0.001) at the expense of oxidation of carbohydrates (65.6% vs. 71.4%, p < 0.001), while there was no significant effect on the oxidation of protein (5.5% vs. 6.3%). Consequently, the non-protein respiratory quotient (RQnp) was lower in the rats fed the CLA-diet than in the rats fed the Control-diet (0.907 vs. 0.928, p < 0.001). Plasma total lipids of the CLA-fed rats had higher concentrations of the cis-9, trans-11 than the trans-10, cis-12 CLA-isomer. This study shows that young male Wistar rats respond to CLA fed as structured triacylglycerol. [ABSTRACT FROM AUTHOR] more...

Abstract: A comparison of membrane fouling caused by filtration of a protein (BSA) through two macroporous membranes, one polymeric (polysulfone) and other ceramic (ZrO2/Al2O3), is carried out. Clean and fouled membranes were characterized by SEM micrographs, water permeability, streaming/zeta potential and impedance spectroscopy measurements. SEM micrographs show BSA on the polymeric and ceramic membranes surfaces but only the polymeric membrane is completely covered, while trans-membrane (or through membrane) zeta potential results indicate protein deposition on the pore walls of both membranes; moreover, differences in time evolution of permeate flow, protein rejection and water permeability for both membranes were also obtained. According to these results, two different main fouling mechanisms can be assumed: a cake layer on the surface of the polysulfone membrane and pore narrowing for the ceramic sample. Impedance spectroscopy measurements allow the estimation of membrane electrical resistance and a reduction in membrane porosity associated to protein deposition was estimated considering a simple system of non-conducting cylindrical capillaries filled by the (conducting) electrolyte solution. [Copyright &y& Elsevier] more...

This study was undertaken to investigate: (1) the effects of both deficiencies and excesses in essential amino acids (EAAs) from an estimated optimum dietary EAA pattern on nitrogen (N) utilization and excretion of rainbow trout Oncorhynchus mykiss, (2) the effects of dietary digestible protein ( PD): digestible energy ( ED) ratio ( PD: ED) on N utilization and excretion of O. mykiss and (3) the potential interaction of these two factors. A 3 × 3 factorial experiment was conducted, with the two factors EAA pattern and PD: ED ratio. The three levels of EAA pattern were: (1) optimum EAA pattern, (2) 60% deficiencies in the three amino acids arginine, histidine and lysine, and (3) 60% excesses in the three amino acids arginine, histidine and leucine. The three levels of PD: ED ratio were 18, 21 and 24 g MJ−1. Amino acid deficiencies from an optimum amino acid pattern caused reductions in mean N retention of 29 to 37%, with the greatest reduction associated with the lowest PD: ED ratio, and similar substantial increases in total N and ammonia-N excretion at all of the dietary PD: ED ratios investigated. Amino acid excesses, however, did not negatively affect N retention or excretion. Increasing PD: ED ratio was associated with decreasing N retention and increasing N excretion over the range of dietary protein and lipid levels tested. Results of this study showed that a diet with optimum dietary amino acid pattern and lowest PD: ED ratio produced the highest N retention (47% of ingested N) and the lowest total N and ammonia-N excretion of O. mykiss. [ABSTRACT FROM AUTHOR] more...

Formylglycine-generating enzyme (FGE) catalyzes in newly synthesized sulfatases the oxidation of a specific cysteine residue to formylglycine, which is the catalytic residue required for sulfate ester hydrolysis. This post-translational modification occurs in the endoplasmic reticulum (ER), and is an essential step in the biogenesis of this enzyme family. A paralog of FGE (pFGE) also localizes to the ER. It shares many properties with FGE, but lacks formylglycine-generating activity. There is evidence that FGE and pFGE act in concert, possibly by forming complexes with sulfatases and one another. Here we show that human pFGE, but not FGE, is retained in the ER through its C -terminal tetrapeptide PGEL, a noncanonical variant of the classic KDEL ER-retention signal. Surprisingly, PGEL, although having two nonconsensus residues (PG), confers efficient ER retention when fused to a secretory protein. Inducible coexpression of pFGE at different levels in FGE-expressing cells did not significantly influence the kinetics of FGE secretion, suggesting that pFGE is not a retention factor for FGE in vivo. PGEL is accessible at the surface of the pFGE structure. It is found in 21 mammalian species with available pFGE sequences. Other species carry either canonical signals (eight mammals and 26 nonmammals) or different noncanonical variants (six mammals and six nonmammals). Among the latter, SGEL was tested and found to also confer ER retention. Although evolutionarily conserved for mammalian pFGE, the PGEL signal is found only in one further human protein entering the ER. Its consequences for KDEL receptor-mediated ER retrieval and benefit for pFGE functionality remain to be fully resolved. [ABSTRACT FROM AUTHOR] more...

Abstract: A two-step methodology has been developed for the prediction of protein retention time in linear-gradient HIC systems. Isocratic retention parameters were determined from ln(k′)-salt concentration plots for a number of commercially available proteins with a range of properties. Quantitative structure property relationship (QSPR) models based on a support vector machine (SVM) approach were generated for predicting isocratic retention parameters for proteins not included in the model generation. The predicted parameters were then used to calculate protein gradient retention times and the results indicate that this approach is well suited for predicting experimental gradient retention data. The approach presented in this paper may have implications for HIC methods development at both the bench and process scales. [Copyright &y& Elsevier] more...

Abstract: The retention of proteins in hydrophobic interaction chromatographic (HIC) systems was investigated using the preferential interaction theory in concert with quantitative structure property relationship (QSPR) modeling. The numbers of water molecules and salt ions released upon protein binding were determined from ln(k′) vs. salt concentration plots for a large number of proteins with a range of properties. The effect of salt type on protein binding was also studied by comparing the number of water molecules released in the presence of different salts. Quantitative structure property relationship (QSPR) models based on a support vector machine (SVM) approach were successfully generated for predicting the water molecules released values. These models employed protein crystal structure and primary sequence information as well as a set of hydrophobicity descriptors based on the solvent accessible surface area of the proteins. In addition to successfully predicting the water release values, the selected descriptors provide insights into the protein physicochemical properties which influence protein affinity in HIC system. [Copyright &y& Elsevier] more...

Abstract: The effects of feed intake level on energy and nitrogen partitioning were studied in juvenile Atlantic cod (250 g) fed two fish meal based diets differing in protein and lipid content (54:31 and 65:16) at 10 °C. Replicate groups of cod were feed deprived for 32 days or fed one of the two diets at 25, 50, 75 or 100% of group satiation for 60 days. Feed intake and oxygen consumption were measured daily and weights and chemical composition of carcass, liver, viscera and whole body were measured at start and end. Diet digestibilities were assessed in a separate experiment. The whole body and carcass growth rates at a given feed intake did not differ between dietary groups, but the liver grew faster in the fish fed the low protein diet, resulting in higher hepatosomatic indices at the end of the experiment in the groups fed this diet. The efficiency of utilisation of digestible nitrogen for growth (k DNg) was higher for the low protein diet (0.73±0.02) than for the high protein diet (0.53±0.05), resulting in higher nitrogen retention at a given nitrogen intake. No difference in percentage nitrogen retention was seen in full-fed fish however (31.2±2.5 and 28.4±1.6% for the low protein and high protein diets, respectively). This can be explained by higher nitrogen intake in the fish fed the high protein diet, resulting in a smaller proportion of the intake being used for maintenance. There was no difference in energy utilisation between dietary groups. The digestible energy requirement for maintenance (DEmaint) was 53.8±0.9 kJ kg−1 d−1 (42.3±0.7 kJ kg−0.8 d−1) and the utilisation efficiency for growth (k DEg) was 0.80±0.02. The energy retention in full-fed fish was 31.3±3.5 and 31.7±1.0% for the low protein and high protein diets, respectively. The deposited energy was distributed in approximately equal proportions in the liver and carcass, whereas viscera accounted for a minor proportion. At a given energy intake, the fish fed the high protein diet deposited more energy in the carcass and less in the liver than did those fed the low protein diet. [Copyright &y& Elsevier] more...

A study was conducted to evaluate fish meal-free practical diets, with and without amino acid supplementation, for the rearing of first feeding Nile tilapia, Oreochromis niloticus. A basal diet was formulated that appeared marginally deficient in lysine, methionine and threonine; thus, experimental diets were supplemented with all possible combinations of those three essential amino acids. Diets contained 45% crude protein and 12% lipid. Diets were fed to apparent satiation four times daily (0800, 1100, 1400, and 1700 hours) for a period of 30 days. No significant differences (P < 0.05) in specific growth rate, weight gain, apparent consumption, food conversion ratio or survival were observed. A significant difference (P < 0.01) in protein retention was observed between fish fed the positive control diet (51.84%) and experimental treatments (22.80-35.17%). This initial evaluation of fish meal-free practical diets for first feeding Nile tilapia demonstrates the potential for eliminating fish meal in diets for larval tilapia, but additional research appears needed to enhance retention of amino acids. doi:10.1300/J028v19n03_06 [ABSTRACT FROM PUBLISHER] more...

A study was conducted to evaluate fish meal-free practical diets, with and without amino acid supplementation, for the rearing of first feeding Nile tilapia, Oreochromis niloticus. A basal diet was formulated that appeared marginally deficient in lysine, methionine and threonine; thus, experimental diets were supplemented with all possible combinations of those three essential amino acids. Diets contained 45% crude protein and 12% lipid. Diets were fed to apparent satiation four times daily (0800, 1100, 1400, and 1700 hours) for a period of 30 days. No significant differences (P < 0.05) in specific growth rate, weight gain, apparent consumption, food conversion ratio or survival were observed. A significant difference (P < 0.01) in protein retention was observed between fish fed the positive control diet (51.84%) and experimental treatments (22.80-35.17%). This initial evaluation of fish meal-free practical diets for first feeding Nile tilapia demonstrates the potential for eliminating fish meal in diets for larval tilapia, but additional research appears needed to enhance retention of amino acids. doi:10.1300/J028v19n03_06 [ABSTRACT FROM PUBLISHER] more...

Exit of soluble secretory proteins from the endoplasmic reticulum (ER) can occur by receptor-mediated export as exemplified by blood coagulation factors V and VIII. Their efficient secretion requires the membrane lectin ER Golgi intermediate compartment protein-53 (ERGIC-53) and its soluble luminal interaction partner multiple coagulation factor deficiency protein 2 (MCFD2), which form a cargo receptor complex in the early secretory pathway. ERGIC-53 also interacts with the two lysosomal glycoproteins cathepsin Z and cathepsin C. Here, we tested the subunit interdependence and cargo selectivity of ERGIC-53 and MCFD2 by short interference RNA-based knockdown. In the absence of ERGIC-53, MCFD2 was secreted, whereas knocking down MCFD2 had no effect on the localization of ERGIC-53. Cargo binding properties of the ERGIC-53/MCFD2 complex were analyzed in vivo using yellow fluorescent protein fragment complementation. We found that MCFD2 is dispensable for the binding of cathepsin Z and cathepsin C to ERGIC-53. The results indicate that ERGIC-53 can bind cargo glycoproteins in an MCFD2-independent fashion and suggest that MCFD2 is a recruitment factor for blood coagulation factors V and VIII. [ABSTRACT FROM AUTHOR] more...

Stability of protein-encapsulating DRV (dried-rehydrated vesicle) liposomes is evaluated after freeze-drying vesicles in presence (or not) of trehalose. Two proteins, bovine serum albumin (BSA) and tissue-type plasminogen activator (t-PA), are used, and protein-encapsulating liposomes with different lipid compositions are prepared by DRV technique. Encapsulation efficiencies are calculated, after measuring BSA with a fluorescence technique and t-PA's amidolytic activity toward a chromogenic substrate.Experimental results show that encapsulation of BSA in vesicles ranges between 35 and 53% of the protein and is only slightly affected by lipid composition. For t-PA, entrapment efficiencies are lower, ranging between 2 and 16%, while lipid composition has substantial effect on entrapment (cholesterol inclusion is very important). After freeze-drying, some lipid compositions remain stable, retaining most of initially entrapped proteins, while others do not, but they may be stabilized by trehalose. In the case of BSA, liposome behavior cannot be explained based on lipid membrane rigidity (more rigid = more stable). This may be connected with previously demonstrated interactions of BSA with membranes. Oppositely, t-PA behavior is more predictable, meaning that the lipid composition selected for the specific therapeutic application determines the need for cryoprotectant addition before freeze-drying t-PA containing DRV liposomes, perhaps due to the fact that under conditions applying minimum or no interactions between t-PA and lipid membranes occur.Thereby, interactions between proteins and membranes determine not only the encapsulation efficiency but also the need for cryopreservation of liposomal protein formulations. [ABSTRACT FROM AUTHOR] more...

Abstract: A novel set of protein descriptors has been developed to increase the understanding of protein behavior on chromatographic media. The protein descriptors are pH-dependent and based on electrostatic and hydrophobic properties of mainly the surface of the proteins as revealed by their three-dimensional structure. Interpretable and predictive quantitative structure property relationship (QSPR) models were then obtained for protein retention in ion exchange chromatography at different pH values. In most cases the calculated average surface potential could be directly related to retention times. Moreover, the high retention of human lactoferrin observed in cation exchange even at high pH values could be modeled by adding descriptors of the charge asymmetry. [Copyright &y& Elsevier] more...