Among the proposed functions of carotenoids in aquaculture have been those of pigmentation, antioxidant functions, as a source of pro‐vitamin A, cellular protection from photodynamic damage, enhancement of growth and reproductive potential. However results reported by various authors are often contradictory. Some evidence suggests that these pigments may perform vital roles in growth and reproductive success in Crustaceans. Additional efforts need to be devoted to the understanding of the active forms of the carotenoid derived metabolites, retinoids in crustaceans. Dietary carotenoids are the sole biological precursors of retinoids in crustaceans. The importance of carotenoids as bioactive molecules reside to a large degree on their conversion to retinoids that are involved in the activation of hormonal nuclear receptors. Retinoids play a prominent role in many developmental processes, including embryonic development and differentiation of various cell types. The presence of receptors of retinoic acid in crustaceans and our findings of retinoids in the neuroendocrine complex and in reproductive tissue, as well as the enhancement of the ovarian development in shrimp suggests an important role of these metabolites in shrimp physiology for their successful aquaculture.

Functional feed supplemented with alternative-economic nutrient sources (protein, carbohydrates, lipids) and probiotics are being considered in shrimp/fish aquaculture production systems as an option to increase yield and profits and to reduce water pollution. In this study the probiotic potential to formulate functional feeds have been evaluated using four dietary treatments: Treatment 1 (B + Bs); Bacillus subtilis potential probiotic strain was supplemented to a soybeanmeal (SBM)—carbohydrates (CHO) basal feed. Treatment 2 (B + Bm); Bacillus megaterium potential probiotic strain was supplemented to the same SBM-CHO basal feed. In Treatment 3 (B); SBM-CHO basal feed was not supplemented with probiotic strains. Treatment 4 (C); fishmeal commercial feed (FM) was utilized as positive control. Feeding trials evaluated the survival, growth, and food conversion ratio and stress tolerance of juvenile Litopenaeus vannamei (Boone) Pacific white shrimp. Best overall shrimp performance was observed for animals fed with Treatment 1 (B+Bs); additionally, stress tolerance and hemolymph metabolites also showed the best performance in this treatment. SBM-CHO basal feed not supplemented with probiotic strains (B) presented smaller growth and lower feed conversion ratio (FCR). Shrimps fed with the fishmeal commercial feed (C) presented the lowest stress tolerance to high ammonia and low oxygen levels. Specifically selected B. subtilis strains are recommended to formulate functional and economical feeds containing high levels of vegetable; protein and carbohydrates as main dietary sources in L. vannamei cultures.

Background: Dunaliella salina is the most important species of the genus for β-carotene production. Several investigations have demonstrated that D. salina produces more than 10% dry weight of pigment and that the species grows in salt saturated lagoons. High plasticity in the green stage and the almost indistinguishable differences in the red phase make identification and differentiation of species and ecotypes very difficult and time consuming.

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In farm-raised marine organisms, the interactions and functions of carotenoid and retinoid micronutrients as free radical scavengers during specific physiological processes, such as gonadic maturation, are not known. Captive and wild female white shrimp, Litopenaeus vannamei, were sampled at two maturation stages: II and IV. Total carotenoids, a carotenoid profile, and vitamin A from the digestive gland and ovary were determined. Superoxide dismutase (SOD) activity was determined in hemolymph. The carotenoid concentration and range of activity were significantly higher (P < 0.05) in wild than in captive shrimp, particularly at maturation stage IV. Activity of SOD in hemolymph of captive shrimp at both stages of maturation was significantly greater (P < 0.05) than that of wild organisms. In sexually exhausted, level IV captive shrimp, low carotenoid concentrations, mainly in digestive gland and ovary, reflected scavenger action insufficient to neutralize oxidative stress processes, as suggested by SOD activity. Carotenoids are important nutrients associated with the reproductive capacity of shrimp. KEY WORDS

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Constructed ammonium oxidizing biofilms (CAOB) and constructed nitrite oxidizing biofilms (CNOB) were characterized during the bioremediation of a wastewater effluent. The maximum ammonium removal rate and removal efficiency in CAOB was 322 mg N-NH4+ m(-3) d(-1) and 96%, respectively, while in CNOB a maximum removal rate of 255 mg N-NH4+ m(-3) d(-1) and a removal efficiency of 76% was achieved. Both constructed biofilms on low-density polyester Dacron support achieved removal efficiencies higher than that of the concentrations normally present in reactors without constructed biofilms (P < 0.05). Nitrifying bacteria from the constructed biofilms cultures were typed by sequencing 16S rRNA genes that had been amplified by PCR from genomic DNA. Analysis of enrichment biofilms has therefore provided evidence of high removal of ammonium and the presence of Nitrosomonas eutropha, N. halophila and N. europaea in CAOB, while in CNOB Nitrobacter hamburgensis, N. winogradskyi and N. alkalicus were identified according to 16S rRNA gene sequences comparison. The biofilm reactors were nitrifying over the whole experimental period (15 days), showing a definite advantage of constructed biofilms for enhancing a high biomass concentration as evidenced by environmental electron microscopic analysis (ESEM). Our research demonstrates that low-density polyester Dacron can be effectively used for the construction of nitrifying biofilms obtaining high removal efficiencies of nitrogen in a relatively short time from municipal effluents from wastewater treatment plants. CAOB and CNOB are potentially promissory for the treatment of industrial wastewaters that otherwise requires very large and expensive reactors for efficient bioremediation of effluents.

D. salina is one of the recognized natural sources to produce β-carotene, and an useful model for studying the role of inhibitors and enhancers of carotenogenesis. However there is little information in D. salina regarding whether the isoprenoid substrate can be influenced by stress factors (carotenogenic) or selective inhibitors which in turn may further contribute to elucidate the early steps of carotenogenesis and biosynthesis of β-carotene. In this study, Dunaliella salina (BC02) isolated from La Salina BC Mexico, was subjected to the method of isoprenoids-β-carotene interference in order to promote the interruption or accumulation of the programmed biosynthesis of carotenoids. When Carotenogenic and non-carotenogenic cells of D. salina BC02 were grown under photoautotrophic growth conditions in the presence of 200 µM fosmidomycin, carotenogenesis and the synthesis of β-carotene were interrupted after two days in cultured D. salina cells. This result is an indirect consequence of the inhibition of the synthesis of isoprenoids and activity of the recombinant DXR enzyme thereby preventing the conversion of 1-deoxy-D-xylulose 5-phosphate (DXP) to 2-C-methyl-D-erythritol (MEP) and consequently interrupts the early steps of carotenogenesis in D. salina. The effect at the level of proteins and RNA was not evident. Mevinolin treated D. salina cells exhibited carotenogenesis and β-carotene levels very similar to those of control cell cultures indicating that mevinolin not pursued any indirect action in the biosynthesis of isoprenoids OPEN ACCESS Mar. Drugs 2009, 7 46and had no effect at the level of the HMG-CoA reductase, the key enzyme of the Ac/MVA pathway.