The metabolism of Artemia salina (L.)

Some aspects of the metabolism of Artemia have been investigated. Experiments have been made with animals of different stocks, obtained from different localities.The growth of Artemia is influenced not only by the sex of the animal, but also by the stock from which it is derived. Likewise, the effect of the salinity of the medium on growth varies with sex and stock. The growth of Artemia is retarded in brine with a low dissolved oxygen content.Changes in body proportions occur with increase in size of Artemia: in particular, the abdomen becomes relatively longer. Body form is also influenced by the salinity of the external medium. The extent to which this occurs varies with the sex of the animal and the stock from which it is derived.The oxygen consumption of Artemia has been measured in relation to the size and sex of the animal and also to the salinity of the medium and its dissolved oxygen content. Females have the same rate of oxygen uptake in sea water as in more concentrated brine. Malesin sea water have a higher rate of oxygen uptake than in concentratedbrine. This difference has been related to the greater area of the second antennae of males in sea water.The colours of Artemia are due mainly to haem compounds andcarotenoids. Haemoglobin occurs in solution in the blood; the role of this pigment in the life of Artemia has been investigated. The colours of the eggs are due to differences in total haem content of the egg shell. The red colour of the nauplius and of certain adults is due to carotenoids; some of these have been identified.<p

A review of carotenoid utilisation and function in crustacean aquaculture

Crustaceans are cultured extensively around the world in intensive farming systems. High-performance formulated feeds have been developed for crustacean aquaculture, which are often supplemented with a number of natural and synthetic carotenoid sources. Studies over a number of years have consistently shown that dietary carotenoid supplementation is beneficial for crustacean aquaculture across a range of commercially relevant parameters. Most obvious is the effect on pigmentation, where carotenoid inclusion levels in feeds and duration of feeding diets with carotenoids have been optimised across many species to improve product colour, and subsequently quality and price. However, beneficial effects of carotenoid inclusion have increasingly been demonstrated on other parameters. This review updates the recent progress in our understanding of dietary carotenoid utilisation and storage, and the combined effects of diet, genetics and environment on crustacean pigmentation. In addition, the range of other physiological benefits this class of molecules brings to these animals is summarised. These include improvements in survival, growth, reproductive capacity, disease resistance and stress resistance. &copy; 2015 Wiley Publishing Asia Pty Ltd

In Vitro Bioactivity of Astaxanthin and Peptides from Hydrolisates of Shrimp (Parapenaeus longirostris) By-Products: From the Extraction Process to Biological Effect Evaluation, as Pilot Actions for the Strategy "From Waste to Profit"

Non-edible parts of crustaceans could be a rich source of valuable bioactive compounds such as the carotenoid astaxanthin and peptides, which have well-recognized beneficial effects. These compounds are widely used in nutraceuticals and pharmaceuticals, and their market is rapidly growing, suggesting the need to find alternative sources. The aim of this work was to set up a pilot-scale protocol for the reutilization of by-products of processed shrimp, in order to address the utilization of this valuable biomass for nutraceutical and pharmaceuticals application, through the extraction of astaxanthin-enriched oil and antioxidant-rich protein hydrolysates. Astaxanthin (AST) was obtained using "green extraction methods," such as using fish oil and different fatty acid ethyl esters as solvents and through supercritical fluid extraction (SFE), whereas bioactive peptides were obtained by protease hydrolysis. Both astaxanthin and bioactive peptides exhibited bioactive properties in vitro in cellular model systems, such as antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities (IA). The results show higher astaxanthin yields in ethyl esters fatty acids (TFA) extraction and significant enrichment by short-path distillation (SPD) up to 114.80 ± 1.23 µg/mL. Peptide fractions of &lt;3 kDa and 3-5 kDa exhibited greater antioxidant activity while the fraction 5-10 kDa exhibited a better ACE-IA. Lower-molecular-weight bioactive peptides and astaxanthin extracted using supercritical fluids showed protective effects against oxidative damage in 142BR and in 3T3 cell lines. These results suggest that "green" extraction methods allow us to obtain high-quality bioactive compounds from large volumes of shrimp waste for nutraceutical and pharmaceutical applications

Carotenoid Supplementation Enhances Reproductive Success in Captive Strawberry Poison Frogs (Oophaga Pumilio)

Amphibians are currently experiencing the most severe declines in biodiversity of any vertebrate, and their requirements for successful reproduction are poorly understood. Here, we show that supplementing the diet of prey items (fruit flies) with carotenoids has strong positive effects on the reproduction of captive strawberry poison frogs (Oophaga pumilio), substantially increasing the number of metamorphs produced by pairs. This improved reproduction most likely arose via increases in the quality of both the fertilized eggs from which tadpoles develop and trophic eggs that are fed to tadpoles by mothers. Frogs in this colony had previously been diagnosed with a Vitamin A deficiency, and this supplementation may have resolved this issue. These results support growing evidence of the importance of carotenoids in vertebrate reproduction and highlight the nuanced ways in which nutrition constrains captive populations. Zoo Biol. XX:XX-XX, 2013

The biotechnology of effluent-grown Spirulina, and application in aquaculture nutrition

The biotechnology of production and utilisation of the cyanobacterium Spirulina has been well documented. Research has centred mainly on application in human and animal nutrition, and has been motivated by the high protein, vitamin, fatty acid and growth factor contents. The main obstacle in realising the full potential of this feed source has been the high production costs associated with its mass culture in defined media. The observation of blooms of Spirulina in tannery effluent evaporation ponds in Wellington, South Africa, prompted this investigation into the harvesting, and nutritional and toxicological evaluation of this potentially low-cost production system, with the ultimate aim of using the product in aquaculture rations. An investigation of the chemical gradient along the evaporation cascade showed a positive correlation between the prevailing chemical conditions and the dominant species populations. A standing crop of 9.5 tonnes/ha of Spirulina was found to be present in the latter alkaline ponds, characterised by relatively lower organic and sulphur contents. Initial harvesting of the biomass was achieved by the design, construction and implementation of a small-scale screen harvest, which yielded a 25 kg (dry weight) crop. A scale-up model was then designed, and implemented in a technical scale harvest, yielding a crop of 250 kg (dry weight). Both these harvests utilised the bloom of surface-autoflocculated biomass. Concentrated cell slurries were sun-dried on muslin beds, and milled to a coarse powder. An evaluation of the harvest revealed a chemical content similar to other published reports of defined media cultures, with the exception of the protein and amino acid contents. The observed lower levels of the latter two are almost certainly due to the sun-drying method employed, known to reduce the protein content due to thermal denaturation. Legislation demands the strict toxicological evaluation of new protein sources, and because of the effluent-nature of the growth medium of this source of Spirulina, its viability lies only in the application as an animal feed or supplement. A range of toxicological tests were chosen that were targeted to elucidate the possible toxicological constraints of this effluentgrown source of protein in animal nutrition. The nucleic acid and pesticide contents of the harvested biomass were within the prescribed safety ranges. Atomic absorption showed minimal accumulation of minerals and heavy metals from the effluent. A bioassay with the brine shrimp Anemia salina showed that the biomass contained no toxicologically active water-soluble components. A short term feeding trial with new-born chicks showed that supplementation with Spirulina had no effect on the growth rates and feed conversion ratios of the different feeding groups. Pathological analyses showed that the liver was the only target organ to elicit a change in response to supplementation of the diets with Spirulina. A general decrease in liver weight was noted, with Cu, Ca, Fe and Zn being significantly accumulated. A histopathological examination however, showed no cellular and functional aberration from the control animals. The toxicological analyses gave the preliminary safe go-ahead for the evaluation of effluent-grown Spirulina in aquaculture nutrition. The South African abalone Haliotis midae, and the rainbow trout Oncorhynchus mykiss were chosen as representative species of edible cultured organisms. The technology for the culture of the perlemoen abalone is being established in South Africa, with the main area of research being the development of an artificial diet for high density culture. A 40 day growth trial demonstrated that lower concentrations of Spirulina supplemented to an agar-based fishmeal diet resulted in growth rates and feed conversion ratios similar to the control fishmeal and purified-casein diets, and thus has application potential in the nutrition of this high-cost marine delicacy. The aquaculture technology of freshwater rainbow trout is already well established. An eight week feeding trial with various concentrations of Spirulina showed that this effluent-grown protein source can partially replace fishmeal in semi-purified diets. Fish fed Spirulina did not exhibit decisive manifestations of toxicity, as determined in a histopathological study. In addition, Spirulina supplementation resulted in enhanced colouration of the skin and flesh, which may have implications in the aesthetic marketing of this sought-after table fish. The primary aim of this preliminary investigation thus concerned the determination of the biotechnological potential of this effluent-source of Spirulina. A technology transfer from the economically unfeasible defined-media culture was implemented. This project is ultimately aimed as a contribution towards the treatment of tannery wastewater, by the removal of contaminants from the effluent in the form of organic biomass

Consumer and processor methods to control Salmonella and Listeria in shrimp

A common method used by consumers to determine if shrimp are thoroughly cooked when boiling, is to wait until the shrimp float to the top of the water and are pink in color. The purpose of this study was to determine whether the current floating and color cooking method is adequate to ensure the elimination of Listeria and Salmonella species. Furthermore, to determine if processing and storage methods reduce the effectiveness of this method. Shrimp samples were submerged into bacterial suspensions for 30 min then allowed to air dry for 1 hr and color parameters were measured using a colorimeter. Shrimp samples were separated into three groups; day 0, 1, or 2, and stored at 4ºC. The shrimp samples were then treated by placing into boiling water (100°C) on days 0 (inoculation day), 1 and 2. The shrimp were immediately removed from the boiling water once they started floating and color parameters were measured. Bacterial counts were determined by making serial dilutions, spread plating, incubating plates at 37°C for 24 h and calculating Log CFU/g. Typical storage conditions, the use of the additive sodium tripolyphosphate and freezing methods were then tested for their effect on the control of these pathogens in boiled shrimp. Initial bacterial counts ranged from 3.0 to 5.4 Log CFU/g of shrimp. On day 0, 1, and 2 all bacterial counts were reduced to non-detectable levels for shrimp samples that floated in the boiling water. The bacterial counts remained at non-detectable levels during refrigerated (4°C) storage. The redness (a*), yellowness (b*) and lightness (L*) were significantly higher (p\u3c0.0001) in the cooked shrimp compared to uncooked for all days tested. However, the standard deviation for the redness (a*) in the cooked shrimp was large indicating a wide range of pink coloration for all days tested. The flash freezing method led to development of heat resistance in Listeria monocytogenes. Brine freezing was determined to be a better method for microbial reduction. Our results suggest that boiling shrimp until they float will significantly reduce Listeria species and Salmonella species but color change will not and color variation can occur