EVALUATING RECIRCULATING AQUACULTURE SYSTEM NUTRIENT PRODUCTION

While aquaculture production accounts for half of the world fish production, a growing problem emerges with the amount of effluent being produced. Waste treatment of aquaculture effluent is expensive and energy- intensive as conventional approaches to waste remediation have remained mostly unchanged. To improve the economic sustainability, the aquaculture industry needs to integrate with other production systems similarly as terrestrial animal agriculture has done with soil-based crop production. Integrating waste production in a wastes-to-resources approach as fertilizer for hydroponic cropping systems will allow aquaculture producers to monetize waste treatment. However, a full accounting of aquaculture nutrient production is necessary to develop a strategy to monetize costly effluent treatment. Capturing fish waste from aquaculture facilities provide an opportunity to offset operational costs by producing a naturally derived nutrient source as fertilizer. Three replicate recirculating aquaculture systems (RAS) were designed and operated under pilot-scale production conditions to evaluate plant-available nutrient production from two commonly grown aquaculture species, tilapia (Oreochromis niloticus) and rainbow trout (Oncorhynchus mykiss). A nutrient mass balance was conducted while the research systems operated under “pseudo-steady state” conditions. Pseudo-steady state was defined as consistent feeding and waste production activity during periods of fish growth and increasing feed demands while still accounting for fish growth and increasing feed demands. The macro-nutrients Ca, K, Mg, N, and P and micro-nutrients B, Cl, Cu, Fe, Mn, Mo, S, and Zn were analyzed over an 81-day period. Both the tilapia and trout nutrient production experiments revealed that all nutrients required for hydroponic crop production were present and available in the system culture water and effluent streams. Macro-nutrients Ca, K, Mg, P, and N, and micro-nutrients, Cl, Mo, and S were observed primarily in the liquid portion of the wastewater and micro-nutrients B, Cu, Fe, Mn, and Zn were primarily observed in the particulate waste. The results of the first experiment indicated that tilapia excreted 3.39 ± 0.55 g Cu, 10.78 ± 1.90 g Fe, 5.61 ± 1.78 g Mn, 0.23 ± 0.08 g Mo, and 7.26 ± 0.89 Zn, per 100kg feed daily. Many of the tilapia nutrient production rates were determined to be statistically different between systems due to dilution and limits of measurement, notably -4.36 ± 4.78 g B, -76.71 ± 350.20 g Cl, -19.97 ± 163.60 g S, 1172.44 ± 706.72 g Ca, 405.27 ± 740.68 g K, 181.72 ± 196.13 g Mg, 704.34 ± 582.05 g P, and 2896.13 ± 4133.70 g Total Nitrogen (TN), per 100kg feed. The difficulties surrounding the accurate characterization of nutrient production from tilapia RAS were resolved and strict sampling procedures applied to the second nutrient mass balance experiment measuring nutrient production from rainbow trout in RAS. Rainbow trout excreted nutrient production was 706.29 ± 49.58 g Cl, 1.01 ± 0.04 g Cu, 13.41 ± 0.51 g Fe, 7.08 ± 0.71 g Mn, 3.11 ± 0.57 g Mo, 312.95 ± 45.59 g S, 11.95 ± 0.58 g Zn. 2043.37 ± 29.18 g Ca, 659.48 ± 51.15 g K, 445.58 ± 7.61 g Mg, 690.11 ± 42.57 g P, and 5729.49 ± 540.33 g TN, per 100kg feed. It is important to distinguish if the nutrients would be directly available as a fertilizer. This study found that Cl, Mo, S, Ca, K, Mg, P, and N are nutrients solubilized in liquid portion of rainbow trout waste rendering them immediately available for plant uptake. Alternately, B, Cu, Fe, Mn, and Zn, were retained in the solid particulate portion of the rainbow trout waste stream. Nutrients retained in the solid particulates require mineralization to make these nutrients plant available. Differences in nutrient production between the two species are due to variation in the feed composition and physiological distinctions such as gut length and muscle tissue composition. The results from these experiments were inconsistent with the previous literature and differences are likely due to experimental design, system design, feed, fish species, and dilution effects. Experimental design is the key factor that limited the determination of nutrient production in this research because no tracer was used in the diet which would have allowed for a full accounting of nutrients assimilated and expelled by the fish. This research supports the need to establish a predictive model for aquaculture-derived nutrient production for integration with other crop production systems. The results from this study demonstrate that nutrient reuse from RAS is possible for hydroponic crop production, but treatment of RAS effluent will be required to fully develop a valuable nutrient source as many of the nutrients are trapped in the solid particulate form

Metabolites of Purine Nucleoside Phosphorylase (NP) in Serum Have the Potential to Delineate Pancreatic Adenocarcinoma

Pancreatic Adenocarcinoma (PDAC), the fourth highest cause of cancer related deaths in the United States, has the most aggressive presentation resulting in a very short median survival time for the affected patients. Early detection of PDAC is confounded by lack of specific markers that has motivated the use of high throughput molecular approaches to delineate potential biomarkers. To pursue identification of a distinct marker, this study profiled the secretory proteome in 16 PDAC, 2 carcinoma in situ (CIS) and 7 benign patients using label-free mass spectrometry coupled to 1D-SDS-PAGE and Strong Cation-Exchange Chromatography (SCX). A total of 431 proteins were detected of which 56 were found to be significantly elevated in PDAC. Included in this differential set were Parkinson disease autosomal recessive, early onset 7 (PARK 7) and Alpha Synuclein (aSyn), both of which are known to be pathognomonic to Parkinson's disease as well as metabolic enzymes like Purine Nucleoside Phosphorylase (NP) which has been exploited as therapeutic target in cancers. Tissue Microarray analysis confirmed higher expression of aSyn and NP in ductal epithelia of pancreatic tumors compared to benign ducts. Furthermore, extent of both aSyn and NP staining positively correlated with tumor stage and perineural invasion while their intensity of staining correlated with the existence of metastatic lesions in the PDAC tissues. From the biomarker perspective, NP protein levels were higher in PDAC sera and furthermore serum levels of its downstream metabolites guanosine and adenosine were able to distinguish PDAC from benign in an unsupervised hierarchical classification model. Overall, this study for the first time describes elevated levels of aSyn in PDAC as well as highlights the potential of evaluating NP protein expression and levels of its downstream metabolites to develop a multiplex panel for non-invasive detection of PDAC

A53T-alpha-synuclein-overexpression in the mouse nigrostriatal pathway leads to early increase of 14-3-3 epsilon and late increase of GFAP

Parkinson’s disease (PD) is a neurodegenerative disorder frequent at old age characterized by atrophy of the nigrostriatal projection. Overexpression and A53T-mutation of the presynaptic, vesicle-associated chaperone alpha-synuclein are known to cause early-onset autosomal dominant PD. We previously generated mice with transgenic overexpression of human A53T-alpha-synuclein (A53T-SNCA) in dopaminergic substantia nigra neurons as a model of early PD. To elucidate the early and late effects of A53T-alpha-synuclein on the proteome of dopaminergic nerve terminals in the striatum, we now investigated expression profiles of young and old mice using two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) and mass spectrometry. In total, 15 proteins were upregulated and 2 downregulated. Mice before the onset of motor anomalies showed an upregulation of the spot containing 14-3-3 proteins, in particular the epsilon isoform, as well as altered levels of chaperones, vesicle trafficking and bioenergetics proteins. In old mice, the persistent upregulation of 14-3-3 proteins was aggravated by an increase of glial fibrillary acidic protein (GFAP) suggesting astrogliosis due to initial neurodegeneration. Independent immunoblots corroborated GFAP upregulation and 14-3-3 upregulation for the epsilon isoform, and also detected significant eta and gamma changes. Only for 14-3-3 epsilon a corresponding mRNA increase was observed in midbrain, suggesting it is transcribed in dopaminergic perikarya and accumulates as protein in presynapses, together with A53T-SNCA. 14-3-3 proteins associate with alpha-synuclein in vitro and in pathognomonic Lewy bodies of PD brains. They act as chaperones in signaling, dopamine synthesis and stress response. Thus, their early dysregulation probably reflects a response to alpha-synuclein toxicity

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Towards sustainable and ocean-friendly aquafeeds: Evaluating a fish-free feed for rainbow trout (Oncorhynchus mykiss) using three marine microalgae species

Aquaculture, the fastest growing food sector, is expected to expand to produce an additional 30 million metric tons of fish by 2030, thus filling the gap in supplies of seafood for humans. Salmonids aquaculture exploits the vast majority of fishmeal and fish oil rendered from ocean-dwelling forage fish. Most forage fish diverted to these commodities are human-food grade, and all are primary prey for marine predators. Rising costs, price volatility, and environmental sustainability concerns of using these commodities for aquaculture feed are driving the global search for alternatives, including marine microalgae originating from the base of marine food webs but produced in culture. We report the first evaluation of two marine microalgae, Nannochloropsis sp. and Isochrysis sp., for their potential to fully replace fishmeal and fish oil in diets of rainbow trout (Oncorhynchus mykiss), an important model for all salmonid aquaculture. We conducted a digestibility experiment with dried whole cells of Nannochloropsis sp. and Isochrysis sp., followed by a growth experiment using feeds with different combinations of Nannochloropsis sp., Isochrysis sp., and Schizochytrium sp. We found that digestibilities of crude protein, crude lipid, amino acids, fatty acids, omega 3 polyunsaturated fatty acids (n3 PUFA), docosahexaenoic acid (DHA), n6 (omega 6) PUFA in Isochrysis sp. were significantly higher than those in Nannochloropsis sp. Digestibility results suggest that for rainbow trout diets Isochrysis sp. is a better substitute for fishmeal and fish oil than Nannochloropsis sp. The lower feed intake by fish fed diets combining multiple microalgae, compared to fish fed the reference diet, was a primary cause of the growth retardation. In trout fillets, we detected an equal amount of DHA in fish fed fish-free diet and reference diet. This study suggests that Isochrysis sp. and Schizochytrium sp. are good candidates for DHA supplementation in trout diet formulations

Towards sustainable aquafeeds: Evaluating substitution of fishmeal with lipid-extracted microalgal co-product (Nannochloropsis oculata) in diets of juvenile Nile tilapia (Oreochromis niloticus).

Microalgae companies increasingly seek markets for defatted biomass that is left over after extracting omega-3 rich oil for human nutraceuticals and crude oil for fuels. Such a protein-rich co-product is a promising alternative to unsustainably sourced fishmeal in aquaculture diets. We report the first evaluation of co-product of the marine microalga Nannochloropsis oculata (N. oculata co-product) for replacing fishmeal in diets of Nile tilapia, a globally important aquaculture species. We conducted a nutrient digestibility experiment with N. oculata dried whole cells and N. oculata co-product, followed by an 84-day nutritional feeding experiment with N. oculata co-product. N. oculata co-product, more nutrient-dense than whole cells, had the highest digestibility for lysine, an essential amino acid that is often deficient in terrestrial crop meals; and for 20:5 n-3 EPA, making it a good option for EPA supplementation in tilapia feed. N. oculata co-product, despite containing higher amounts of protein than whole cells, had significantly lower digestibility for crude protein than whole cells. Apparent digestibility coefficients (ADC) of methionine were significantly lower in N. oculata co-product than in whole cells. The nutritional feeding experiment compared diets with N. oculata co-product that replaced fishmeal as follows: 0% replacement in reference diet (fishmeal as 7% of total diet) and test diets with 33%, 66% and 100% replacement of fishmeal (3%, 5.5%, and 8% of total diet, respectively). Results showed the 33% replacement diet yielded fish growth, feed conversion, and survival similar to the reference diet. Reduced digestibility and growth at greater N. oculata co-product inclusion levels may have been due to higher levels of anti-nutrients in co-product than whole cells. All diets yielded a n3:n6 ratio of tilapia fillet that is favorable for human consumption. Depositions of macro minerals and several trace elements in the fillet were not significantly different across diets. Thus, N. oculata co-product, when replacing 33% of fishmeal in tilapia feed, led to fish performance and flesh composition comparable to that of fish fed the reference diet, but its nutrient digestibility needs to be improved to achieve higher replacement levels

Proximate analysis, and gross energy, essential amino acid and fatty acid profiles of the reference and test diets.

<p>Proximate analysis, and gross energy, essential amino acid and fatty acid profiles of the reference and test diets.</p

Ingredient composition of the reference diet (g kg^-1).

<p>Ingredient composition of the reference diet (g kg^-1).</p

Macro minerals and trace elements in the <i>Nannochloropsis oculata</i> (<i>Nanno</i>) whole cells and co-product.

<p>Macro minerals and trace elements in the <i>Nannochloropsis oculata</i> (<i>Nanno</i>) whole cells and co-product.</p

Fatty acid (% of total fatty acids) content of fillets from Nile tilapia after 84 days on the experimental diets; average ± SE for 3 replicates per diet (pooled whole tissues of 5 fish/replicate)^§.

<p>Fatty acid (% of total fatty acids) content of fillets from Nile tilapia after 84 days on the experimental diets; average ± SE for 3 replicates per diet (pooled whole tissues of 5 fish/replicate)^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201315#t013fn002" target="_blank">§</a>}.</p