International study on <i>Artemia</i> (1). XVII. Energy consumption in cysts and early larval stages of various geographical strains of <i>Artemia</i>

Variations in dry weight, caloric content and ash content during cyst hatching and early larval development have been studied for various geographical strains of Artemia. In general, decapsulated cysts contain 30 to 40 % more energy than freshly hatched nauplii; for Chaplin Lake and Buenos Aires Artemia this difference amounts to 57 %. Ash contents increase as decapsulated cysts hatch into instar I and molt into instar II-III nauplii. Over a 24 h larval developmental period individual dry weights and energy contents of the nauplii decrease with 16-34 % and 22-37 % respectively.A small but significant correlation exists between the survival rate of starved nauplii and either the energy content of instar I and instar II-III nauplii or the proportional energy consumption during metabolism from decapsulated cysts to instar II-III nauplii. The potential impact of these results on the use of Artemia in aquaculture hatcheries is discussed

Feeding enriched <i>Artemia</i> biomass to <i>Penaeus vannamei</i> broodstock: its effect on reproductive performance and larval quality

Two experiments were conducted co-feeding Penaeus vannamei broodstock with frozen Artemia biomass. In the first experiment, animals were fed natural diets supplemented with squid (treatment SQ), Artemia (A), or enriched Artemia (EA). fn the second experiment, animals received a supplement of Artemia enriched with different products; rich in polyunsaturated fatty acids (PUFA) and cholesterol (treatment L), rich in vitamin c, vitamin e,and astaxanthin (treatment V), or a complete enrichment (treatment LV). In experiment 1, treatment SQ gave poor results for most parameters. Supplementation with Artemia resulted in higher survival, higher maturation frequency, a higher incidence of repeated spawns, and an improved larval quality. The best results were obtained in the treatment that received enriched Artemia. In experiment 2, the highest reproductive performance was obtained through enrichment of Artemia with both lipids and vitamins (LV). By reducing the concentration of PUFA and cholesterol in the enrichment product, a decline in egg fertilization, a lower incidence of repeated spawns, and a lower egg production per female was observed. High vitamin levels played a positive role only when provided in combination with high levels of PUFA and cholesterol. If not, symptoms of oversaturation occurred

The use of <i>Artemia</i> in marine fish larviculture

Among the live diets used in the larviculture of fish and shellfish, the brine shrimp Artemia nauplii constitute the most widely used food item; i.e., over 700 metric tons of dry Artemia cysts are annually marketed worldwide for on-site hatching into 0.4 mm nauplii.Although the use of Artemia appears to be simple, considerable progress has been made in the past decade in improving and increasing its value as a larval diet for marine fish larvae. The improvements include: identification of the most appropriate strains and batches; new techniques for cyst disinfection; decapsulation and hatching; and enrichment and cold storage of nauplii. Using particulate or emulsified products rich in highly unsaturated fatty acids or n-3 HUFAs, the nutritional quality of Artemia can be further tailored to suit the predators' requirements by bio-encapsulating specific amounts of these products in the Artemia metanauplii. Application of the method of bioencapsulation, also called Artemia enrichment or boosting, has had a major impact on larviculture output, not only in terms of survival, growth and success of metamorphosis of the fish, but also with regard to their quality, e.g., reduced malformations, improved pigmentation and increased stress-resistance. Nonetheless, in many species survival rates are still marginal.For several marine fish species, the optimal dietary levels of n-3 HUFAs are still not met by enriched Artemia . Furthermore, while n-3 HUFAs might have proven most critical, it is very likely that other nutrients (e.g., other lipid classes, vitamins and free amino acids) might appear equally important and in some species even more critical. The bio-encapsulation technique can also be used for the oral delivery of hormones and therapeutics to the fish larvae. Artemia juveniles, grown to a size that suits the feeding behaviour of the growing predator and/or adult biomass collected from local saltworks or mass production units, can be used as an excellent nursery and weaning diet for most species of marine fish, eventually reducing fish mortalities, cannibalism and heterogeneous growth

Increased yields of marine fish and shrimp production through application of innovative techniques with <i>Artemia</i>

The larval culture of fish and shrimp can be seriously improved thanks to the results of recent research and developments in the field of Artemia production and utilisation.The present article provides a historical overview of Artemia cyst demand and provision, summarizes the latest results of Artemia production in extensive and intensive culture systems and correlates the increased outputs in fish and shrimp hatcheries with improved applications of various Artemia products

On the role of SOCS proteins in leptin signalling

Leptin is a pleiotropic cytokine that was initially identified as a key player in food intake and energy expenditure. It is produced mainly in adipose tissue and circulating leptin levels correlate well with the amount of body fat. As an adipostat, leptin passes the blood brain barrier to inform the hypothalamus about the status of energy reserves in the body. Appropriate responses are triggered to maintain a stable body mass. Most obese individuals have developed a state of leptin resistance because their body is not capable of reacting properly to the leptin signal. This leptin insensitivity can be caused by defects at different levels in the leptin pathway including leptin transport through the blood brain barrier, hypothalamic leptin signalling and downstream effects of leptin in the neuronal circuit. In addition, leptin is involved in a broad range of other, often peripheral, physiological functions including reproduction, bone formation and immunity, and may also contribute to the development of disorders like auto-immune diseases. There are at least six splice variants of the leptin receptor but only the one with a long cytoplasmic tail has full signalling capacities. It typically signals through the JAK-STAT pathway via JAK2 and predominantly STAT3. Since leptin action is of great importance throughout the body, signalling must be under stringent control. SOCS3 and PTP1B are the best characterized mediators of leptin signalling termination. In this work we focus on the role of SOCS proteins in leptin receptor signalling. SOCS proteins are typically inhibitors of cytokine receptor signalling and consist of an SH2-domain that mediates association with phosphotyrosine motifs, an N-terminal preSH2-domain and a C-terminal SOCS-box that is responsible for targeting associated proteins for proteasomal degradation. We identified two members of the SOCS family, CIS and SOCS2, as new interaction partners of the LR. We studied the binding modus of SOCS proteins and demonstrated that the SOCS-box is essential for receptor interaction of CIS but not of other examined SOCS proteins. In addition, we demonstrated that cross-modulation between SOCS proteins depends on direct interaction and requires elongin B/C recruitment to the SOCS-box which implicates a role for proteasomal degradation

Variation in egg and larval quality in various fish and crustacean species

It is generally accepted, that a major constraint in the further development of marine fish and crustacean aquaculture, is the variable quality of eggs and larvae used for the hatchery-production of fry. Nonetheless, valid criteria to evaluate optimal egg quality have not been identified yet. Instead, particular indicators, are used, e.g. the fertilization and hatching rate, overall culture success during the first rearing period, etc., but these are not totally objective because hatchery-specific conditions may interfere. The biochemical composition of the egg may be one of the possible determinants of egg quality, which can be evaluated on a more objectie basis. In this respect, studied have been initiated to analyze in freshly-released eggs, the levels of two nutrients which are believed to play a critical role in the early larval development, i.e. (n-3) highly unsaturated fatty-acids (HUFAs) and vitamin C. Analytical data have been gathered for various species of marine fishes (Scophthalmus maximus, Epinephelus tauvina and E. fuscoguttatus, Dicentrarchus labrax, Sparus aurata, and Pagrus major) and for the freshwater prawn (Macrobrachium rosenbergii). Egg samples have been collected from wild females and from captive broodstock kept under various conditions at various hatcheries. Results available so far illustrate that for some of the species tested HUFA levels and total lipid content in the eggs vary considerably among spawnings, even when coming from the same hatchery. The highest variation was noted in turbot broodstock, i.e. the HUFA levels and total lipid content ranged from 19 to 47 mg/g DW, and 8 to 30%, respectively. Contents of ascorbic acid in turbot eggs varied up to 100%, respectively 500% among different egg batches provided by two hatcheries

Relationship between egg quality and fatty acid content of various turbot broodstocks (Scophthalmus maximus L.)

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