Differential dynamics of the serotonin(1A) receptor in membrane bilayers of varying cholesterol content revealed by all atom molecular dynamics simulation

The serotonin(1A) receptor belongs to the superfamily of G protein-coupled receptors (GPCRs) and is a potential drug target in neuropsychiatric disorders. The receptor has been shown to require membrane cholesterol for its organization, dynamics and function. Although recent work suggests a close interaction of cholesterol with the receptor, the structural integrity of the serotonin(1A) receptor in the presence of cholesterol has not been explored. In this work, we have carried out all atom molecular dynamics simulations, totaling to 3s, to analyze the effect of cholesterol on the structure and dynamics of the serotonin(1A) receptor. Our results show that the presence of physiologically relevant concentration of membrane cholesterol alters conformational dynamics of the serotonin(1A) receptor and, on an average lowers conformational fluctuations. Our results show that, in general, transmembrane helix VII is most affected by the absence of membrane cholesterol. These results are in overall agreement with experimental data showing enhancement of GPCR stability in the presence of membrane cholesterol. Our results constitute a molecular level understanding of GPCR-cholesterol interaction, and represent an important step in our overall understanding of GPCR function in health and disease.

Improved utilization and increased availability of fishery products as an effective control of aggravated animal protein deficiency - induced malnutrition in Nigeria

The estimated potential of Nigerian fish resources is 1,830,994 tonnes(t) whereas the demand based on per capita consumption of 12.0kg and a population of 88.5 million is 1.085 million tonnes. Supply is presently less than 500,000 tons. The gap between demand and supply have to be met through improved utilization and increased availability of fish and fishery products. The role of fish in nutrition is recognized, since it supplies a good balance of protein, vitamins and minerals and a relatively low caloric content. This paper appraises the consumption and utilisation pattern of fish in Nigeria, the spoilage of fish and prevention of losses as a means of increasing the availability of fish for human consumption and consequent control of aggravated animal protein deficiency - induced malnutrition. The paper further highlights the point that without increased landings, increased supply of fish can be achieved through reduction of postharvest loss of what is presently caught. The use of newly designed smoke - drying equipment to achieve such goal is highlighted. The paper also emphasises the need to put into human food chain those non-conventional fishery resources and by-catch of shrimp and demersal trawl fishes by conversion into high value protein products like fish cakes, fish pies and salted dried cakes

Effect of gibbing on protein hydrolysis during the ripening of salted herring at 4°C in polypropylene barrels

Effect of gibbing process on the protein hydrolysis in terms of free alpha amino nitrogen (FAN) content during the ripening of barrel salted herring at low temperature (4°C) was investigated. For this purpose North Sea herring (Clupea harengus) from north-east British coast was salted in polypropylene barrels and allowed to ripen at 4°C. This process of barrel salting was carried out for whole fish in one batch and gibbed fish in another batch. The investigation was performed by using new salt and used salt in separate barrels for each batch of experimental fish. Results of the present study show that protein hydrolysis was significantly higher in the ripened salt-herring produced from whole fish which was found to have more characteristic sensory properties than those produced from gibbed fish. Similar result (proteolysis) was obtained when the investigation was repeated for the spent herring although the spent herring fails to produce a ripened product with the desired characteristic sensory attributes, compared to those of pre-spawning herring.

Effect of copper, cadmium and Cu.Cd mixture on amino acid content in the poslarvae of penaeid shrimp, Penaeus monodon and P. penicillatus

This study document effects of short-term (96h) sublethal levels of copper, cadmium and their mixture on the amino acid composition of postlarvae of the penaeid shrimp, P.monodon and P.penicillatus . All experimental conditions were kept constant, temperature between 25-27•C and salinity 21-22 ppt. The estimated LD50 for Cu was 200 ug/L, for Cd 177.5 ug/L and for Cu.Cd mixture 250ug/L. In P. penicillatus at the same concentration of each metal, there was significant reduction in amino acid content, which was 8.01% higher than the control. Almost similar reduction in some amino acids was observed in P.monodon. At the maximum concentration of 400 ug/L, cadmium caused higher reduction in amino acid composition than did copper. Thus, amino acid composition may be regarded as a sensitive biochemical indicator of Cu and Cd toxicity because of the effect of these metals on protein synthesis, a signal of physiological stress in marine organisms subjected to heavy metal pollution.

Protein hydrolysate from miscellaneous fish

A method to prepare fish protein hydrolysate from miscellaneous fish obtained as by catch from shrimp trawlers is outlined. Effect of temperature and concentration of enzyme papain on the yield of hydrolysates has been determined. It is seen that within 30 min at 55°C and pH 6.5 fish proteins can be effectively solubilized, provided the nitrogen content of the enzyme (activity 10 units/mg enzyme) and substrate are maintained in the ratio 1:30. This hydrolysate possesses the best amino acid pattern compared to those obtained after hydrolysis for 60 to 180 min.

Squilla protein: chemical composition and nutritive value

Protein extract prepared from squilla (Grato squilla nepa), a commercially unexploited crustacean, was analysed for crude protein and essential amino acids. All the essential amino acids except tryptophan and threonine were present in nutritionally adequate amounts. The protein was evaluated for its nutritional quality in respect of growth rate, protein efficiency ratio (PER) and liver nitrogen content by feeding on rats. Growth rates and protein efficiency ratios were similar in rats fed on casein, squilla protein and a combination of squilla protein and casein (1:1) diet. The weight of liver and kidneys were normal.

Soluble protein isolated from low cost fish and fish wastes

The method of preparation, composition, amino acid content, protein efficiency ratio and areas of possible application of water soluble protein isolates from low cost fish and fish wastes are discussed in detail in this communication.

The effect of various protein levels on the growth and survival rates of Penaeus monodon Fabricius

Postlarvae of tiger prawns, P. monodon , were fed with various protein levels of 0; 30; 40 and 50%, fish meal and rice bran were combined and pelletized for 16 wks. Prawns used had an average mean length of 1.2 mm and an average mean weight of 5.5 mg. Nitrite, ammonia, dissolved oxygen content, temperature and pH were monitored. After one month of feeding, growth increments of postlarvae fed with 30% protein diet were significantly different from those given 0; 40 and 50%. Survival rate of the group fed 40% protein was higher (81.7%) but was not significantly different from those fed 30% (68.0%). The highest feed efficiency was obtained from the 30% protein pellets (4.6). At the end of 16 weeks, growth increment of 40% protein level was significantly different from the 30% and 50% protein levels, but the survival rate was not signficantly different from the 30% protein level. Feed conversion for the 40% protein diet was 2.8.

Formulation, processing and water stability of pelleted feeds with varying levels of protein used in carp nutrition studies

Four dry pelleted feeds containing 20%, 30%, 40% and 45% protein were formulated incorporating casein as the main source of protein for use in carp nutrition studies. The caloric content in all the feeds was maintained constant. The method of processing is described. The formulated diets were tested for water stability. This test has revealed that the diet containing 20%, 30% and 40% protein had better stability than that containing 45% protein. This was due to the relatively higher fat content in the former three diets. However, all the feeds were sufficiently stable at the end of one hour in which time carps are known to utilise supplementary diets.

Ipil-ipil (Leucaena leucocephala) leaves as a plant protein source in prawn diets

Penaeus monodon juveniles were fed diets containing fish meal, shrimp head meal and ipil-ipil leaves soaked and unsoaked, local and peruvian varieties. Mean weight gain at the end of 8 wk was significantly highest among those given the diet containing commercial ipil-ipil leaves. Gain in length followed the same pattern as mean weight gains. Among the diets containing ipil-ipil leaves there was a direct relationship in the amount of mimosine in the diet and the survival rate, the lower the amount of mimosine (due to soaking) the higher the survival rate. The Results thus indicate the beneficial effect of the addition of commercial ipil-ipil leaves to the diets of prawns, providing the mimosine content is kept low by soaking. A reduce in costs is also obtained, since 1kg of shrimp head meal or fish costs more than 2 or 4 tons, respectively, than that of ipil-ipil foliage.

The effect of various protein levels on the growth and survival rates of Penaeus monodon Fabricius

Postlarvae of tiger prawns, P. monodon, were fed with various protein levels of 0; 30; 40 and 50%, fish meal and rice bran were combined and pelletized for 16 wks. Prawns used had an average mean length of 1.2 mm and an average mean weight of 5.5 mg. Nitrite, ammonia, dissolved oxygen content, temperature and pH were monitored. After one month of feeding, growth increments of postlarvae fed with 30% protein diet were significantly different from those given 0; 40 and 50%. Survival rate of the group fed 40% protein was higher (81.7%) but was not significantly different from those fed 30% (68.0%). The highest feed efficiency was obtained from the 30% protein pellets (4.6). At the end of 16 weeks, growth increment of 40% protein level was significantly different from the 30% and 50% protein levels, but the survival rate was not significantly different from the 30% protein level. Feed conversion for the 40% protein diet was 2.8.

Development of soy protein fortified fish sticks from Tilapia

The objective of this study was to develop soy protein fortified fish sticks from Tilapia. Two preliminary studies were conducted to select the best fish-soy protein-spice mixture combination with four treatments to develop breaded fish sticks. Developed products were organoleptically assessed using 30 untrained panellists with 7-point hedonic scale. The product developed with new combination was compared with market product. Sixty percent of Tilapia fish mince, 12% of Defatted Textured Soy protein (DTSP), 1.6% of salt and 26.4% of ice water (<5°C) and Spice mixture containing 3g of garlic, 2g of pepper 2g of onion and 1.6g of cinnamon were selected as the best formula to manufacture the product. There was no significant difference when compared with market samples in relation to the organoleptic attributes. Proximate composition of the product was 25.76% of crude protein, 2.38% of crude fat, 60.35% of moisture and2.75% of ash. Products were packaged in Poly Vinyl Chloride clear package (12 gauge) and were stored at -1°C and changes in moisture content, peroxide value, pH value and microbiological parameters were assessed during five weeks of storage. Organoleptic acceptability was not changed significantly in all parameters tested (p>0.05). Total aerobic count and yeast and mould count were in acceptable ranges in frozen storage for 5 weeks. Data were analyzed using AN OVA and Friedman non-parametric test.

Effect of the interplay between protein and surface on the properties of adsorbed protein layers.

Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials.

Effect of the interplay between protein and surface on the properties of adsorbed protein layers

Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials. © 2014 The Authors.

Changes in RNA, DNA, protein contents and growth of turbot Scophthalmus maximus larvae and juveniles

The growth potential of turbot Scophthalmus maximus larvae and juveniles was studied using nucleic acid-based indices and protein variables. The experiment was carried out from 4 to 60 days post hatching (dph). A significant increase in instantaneous growth rate during metamorphosis and retarded growth rate during post-metamorphic phase were observed. Ontogenetic patterns of DNA, RNA and protein all showed developmental stage-specific traits. The RNA:DNA ratio decreased up to 12 dph, then increased rapidly till 19 dph and fluctuated until 35 dph followed by a decline to the end. The RNA:DNA ratio was positively correlated with growth rate of juveniles during the post-metamorphic phase, whereas this ratio was not a sensitive indicator of growth during the pre-metamorphic phase and metamorphosis. The protein:DNA ratio showed a similar tendency to the RNA:DNA ratio. Changes of DNA content and protein:DNA ratio revealed that growth of S. maximus performed mainly by hyperplasia from 4 to 12 dph and hypertrophy until 21 dph during the pre-metamorphic larval phase. Growth was dominantly hypertrophical from the early- to mid-metamorphosing phase and hyperplastic thereafter. The results show that the DNA content and protein:DNA ratio can evaluate growth rates of larval and juvenile S. maximus on a cellular level.