Reduction in flavor-intense components in fish protein hydrolysates by membrane filtration.

Enzymatic protein hydrolysates based on side stream materials from the fish-filleting industry are increasingly explored as food ingredients. However, intense sensory properties, and high salt contents, are often a limiting factor. Most of the sensory attributes, such as fish flavor and salty taste, can be ascribed to low-molecular-weight, water-soluble components, whereas bitterness is associated with small hydrophobic peptides. In this study, protein hydrolysates based on head and backbone residuals from Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were produced using two different enzymes. The effects of micro- and nanofiltration on the chemical composition, protein recovery, and sensory properties of the final products were investigated. The choice of raw material and enzyme had negligible effects, whereas nanofiltration caused a considerable reduction in metabolites, ash, and the intensity of several sensory attributes. The intensity of bitterness increased after nanofiltration, indicating that small peptides associated with bitter taste were retained by the membrane. Total protein yield after microfiltration was 24%-29%, whereas 19%-24% were recovered in the nanofiltration retentate. PRACTICAL APPLICATION: Enzymatic protein hydrolysates can be included in food products to increase the protein content, and as a nutritional supplement and/or functional ingredient; however, unpalatable and intense flavors limit applications. This study investigated the use of membrane filtration to improve flavor quality and reduce salt content in fish protein hydrolysates. Although some protein loss is unavoidable in micro- and nanofiltration, this study demonstrates the production of fish protein hydrolysates with >90% protein and peptide content, which is suitable for inclusion in foods.

Food Matrix Reference Materials for Hydrogen, Carbon, Nitrogen, Oxygen, and Sulfur Stable Isotope-Ratio Measurements: Collagens, Flours, Honeys, and Vegetable Oils.

An international project developed, quality-tested, and measured isotope-delta values of 10 new food matrix reference materials (RMs) for hydrogen, carbon, nitrogen, oxygen, and sulfur stable isotope-ratio measurements to support food authenticity testing and food provenance verification. These new RMs, USGS82 to USGS91, will enable users to normalize measurements of samples to isotope-delta scales. The RMs include (i) two honeys from Canada and tropical Vietnam, (ii) two flours from C3 (rice) and C4 (millet) plants, (iii) four vegetable oils from C3 (olive, peanut) and C4 (corn) plants, and (iv) two collagen powders from marine fish and terrestrial mammal origins. An errors-in-variables regression model included the uncertainty associated with the measured and assigned values of the RMs, and it was applied centrally to normalize results and obtain consensus values and measurement uncertainties. Utilization of these new RMs should facilitate mutual compatibility of stable isotope data if accepted normalization procedures are applied and documented.

Protein quality and safety evaluation of sarcoplasmic protein derived from silver carp (Hypophthalmichthys molitrix) using a rat model.

Consisting of 25 to 30% of protein in carp, water-soluble sarcoplasmic proteins lost in wash water, have been recovered and freeze-dried into a protein-rich powder. Study objectives were to evaluate protein quality and safety of a silver carp sarcoplasm derived protein powder (CSP) compared to commercial protein supplements, casein, and whey. In vivo protein quality assessment of CSP showed a lower (P < 0.05) protein digestibility corrected amino acid score compared to the commercial protein sources. Despite greater (P < 0.05) fecal amino acid excretion in casein-fed rats, there were no significant differences in liver and muscle amino acid profiles. All low (10% kcal) protein diets supported growth with the normal range. However, whey protein supplementation resulted in greater (P < 0.05) adiposity. CSP, casein, or whey-fed rats showed no differences in major organ weights, renal damage biomarkers, or bone indices. Collectively, results indicated CSP was safe with protein quality comparable to casein. PRACTICAL APPLICATION: As much as 40 percent of protein in fish can be lost due to sarcoplasmic protein solubilization in processing wash water. Silver carp sarcoplasm protein powder may have similar commercial potential as a sustainable and nutritious alternative to whey and casein proteins. This project aimed to verify the protein quality and safety of this economical protein source.

Adipose tissue contributes to hepatic pro-inflammatory response when dietary fish oil is replaced by vegetable oil in large yellow croaker (Larimichthys crocea): An ex vivo study.

The shortage of fish oil (FO) leads to the extensive use of vegetable oil (VO) in marine fish diets. High replacement percentage of dietary FO by VO induced pro-inflammatory response of adipose tissue (AT) and liver tissue (LT) in large yellow croaker (Larimichthys crocea). Mammalian studies showed that the secretion of cytokines by AT affected the immune response of LT. To investigate whether or not the inflammation response of LT is related to AT in large yellow croaker, LT and AT cells from fish fed FO diet (FOL and FOA) and VO diet (VOL and VOA) were co-cultured in a trans-well system, which resulted in an assembly of the two cells types sharing the culture medium but being separated by the membrane of the insert. Co-culture of FOL and FOA was selected as the control group (FOL-FOA). Results indicated that, when compared with the control group, the expression of pro-inflammatory genes (toll like receptors [TLRs], tumour necrosis factor α [TNFα], interleukin 1ß [IL1ß], suppressor of cytokine signalling 3 [SOCS3] and cyclooxygenase 2 [COX2]) in FOL was significantly increased in the co-culture group of FOL and VOA (FOL-VOA), while the expression of anti-inflammatory genes (arginase I [ArgI] and transforming growth factor ß1 [TGFß1]) in FOL was significantly depressed. On the contrary, a significantly depressed expression of pro-inflammatory genes (TLRs, TNFα, IL1ß and COX2) and increased expression of anti-inflammatory genes (interleukin 10 [IL10]) in VOL was observed in the co-culture group of VOL and FOA (VOL-FOA) when compared with the co-culture group of VOL and VOA (VOL-VOA). The change of immune-related gene expressions in LT cells was attributed to nuclear factor κB (NF-κB) signalling since the expression of the p65 protein was observed to show a similar trend to the expression of pro-inflammatory genes. It is speculated that dietary VO increased the secretion of cytokines, which induced pro-inflammatory response in LT cells. These ex vivo results indicate that AT plays a vital role in LT pro-inflammatory response in fish fed VO diet.

The effect of micronutrient supplementation on growth and hepatic metabolism in diploid and triploid Atlantic salmon (Salmo salar) parr fed a low marine ingredient diet.

The effects of low marine ingredient diets supplemented with graded levels (L1, L2, L3) of a micronutrient package (NP) on growth and metabolic responses were studied in diploid and triploid salmon parr. Diploids fed L2 showed significantly improved growth and reduced liver, hepatic steatosis, and viscerosomatic indices, while fish fed L3 showed suppressed growth rate 14 weeks post feeding. In contrast, dietary NP level had no effect on triploid performance. Whole body mineral composition, with exception of copper, did not differ between diet or ploidy. Whole fish total AAs and N-metabolites showed no variation by diet or ploidy. Free circulating AAs and white muscle N-metabolites were higher in triploids than diploids, while branch-chained amino acids were higher in diploids than triploids. Diploids had higher whole body α-tocopherol and hepatic vitamins K1 and K2 than triploids. Increased tissue B-vitamins for niacin and whole-body folate with dietary NP supplementation were observed in diploids but not triploids, while whole body riboflavin was higher in diploids than triploids. Hepatic transcriptome profiles showed that diploids fed diet L2 was more similar to that observed in triploids fed diet L3. In particular, sterol biosynthesis pathways were down-regulated, whereas cytochrome P450 metabolism was up-regulated. One­carbon metabolism was also affected by increasing levels of supplementation in both ploidies. Collectively, results suggested that, for optimised growth and liver function, micronutrient levels be supplemented above current National Research Council (2011) recommendations for Atlantic salmon when fed low marine ingredient diets. The study also suggested differences in nutritional requirements between ploidy.

Evaluation of the Use of TRIzol-Based Protein Extraction Approach for Gel-Based Proteomic Analysis of Dried Seafood Products and Chinese Tonic Foods.

Although the emergence of gel-free approaches has greatly enhanced proteomic studies, two-dimensional gel electrophoresis (2-DE) remains one of the most widely used proteomic techniques for its high resolving power, relatively low cost, robustness, and high resolution. Preparation of high-quality protein samples remains the key in high-quality 2-DE for proteomic analysis. Samples with high endogenous levels of interfering molecules, such as salts, nucleic acids, lipids, and polysaccharides, would yield a low-quality 2-DE gel and hinder the analysis. Recently, a TRIzol-based protein extraction method has gained prominence and has attracted attention due to its promising performance in high-quality 2-DE. The authors evaluate the use of this approach for four valuable dried food products, namely two dried seafood products (abalone slices and whelk slices) and two traditional Chinese tonic foods (ganoderma and caterpillar fungus). The results indicate that 2-DE gels obtained through the TRIzol-based method are of high-quality and are comparable to those obtained through the trichloroacetic acid⁻acetone method in terms of spot number, spot intensity, and resolution. The TRIzol-based method is generally applicable to dried food samples and is simple and fast, which greatly streamlines the protein extraction procedure. Additionally, it enables the concurrent extraction and analysis of RNA, DNA, and protein from the same sample.

Skin Mucus Protein Profile, Immune Parameters, Immune-Related Gene Expression, and Growth Performance of Rainbow Trout (Oncorhynchus mykiss) Fed White Button Mushroom (Agaricus bisporus) Powder.

An 8-week feeding trial was performed to assess the effects of dietary white button mushroom (Agaricus bisporus) powder (WBMP) on the mucosal immunity and growth of rainbow trout (Oncorhynchus mykiss). Trout (n = 192; weight 13.76 ± 1.17 g) were stocked in 12 cages (65 × 65 × 65 cm) placed in 4 raceways with a flow-through water system. Trout were fed a basal diet (control group) or a basal diet supplemented with 0.5%, 1%, or 2% WBMP for 8 weeks. Evaluation of total protein levels and lysozyme activity in skin mucus revealed noticeable increases in trout fed 1% or 2% WBMP (P < 0.05), but no significant difference was observed with 0.5% WBMP administration (P > 0.05). The results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed alterations in the protein profile of skin mucus following dietary administration of WBMP. Molecular studies showed a noticeable increase (P < 0.05) in tumor necrosis factor-α messenger RNA in the intestine of WBMP-fed trout, regardless of the inclusion level. Also, fish receiving the 1% or 2% WBMP treatments had a remarkable increase in interleukin (IL)-1ß expression compared with the control group (P < 0.05). In a similar way, intestinal IL-8 expression was upregulated with the 1% and 2% WBMP treatments (P < 0.05). However, no significant difference was found between the control group and the 0.5% WBMP treatment group in the case of IL-8 gene expression (P > 0.05). Furthermore, after 8 weeks of WBMP feeding, no improvement was seen in the growth parameters of trout compared with those fish fed the nonsupplemented diet (P > 0.05). These results hint at the potential immunomodulatory effects of dietary WBMP.

Characterization of protein hydrolysates from blue whiting (Micromesistius poutassou) and their application in beverage fortification.

Enzymatic hydrolysis of fish proteins has been employed as a principle method for converting under-utilised fish into valuable products for the pharmaceutical and health food industries. In this study, six commercial enzymes were tested for their ability to make fish protein hydrolysate powders from whole blue whiting. The chemical and functional properties of these powders were compared. The powders all had high solubility (>80%) across a wide pH range in water and their solubility improved further within a vitamin-tea beverage matrix (>85%). Varying degrees of anti-oxidant activities were recorded for the powders using three model systems (DPPH, ferrous chelating and reducing power). This study demonstrates that commercial enzymes are useful for the extraction and alteration of fish protein from a low value source to produce highly digestible, low molecular weight peptide powders that could be used as a fortifying health ingredient, especially in beverages.

In vivo identification of potential uranium protein targets in zebrafish ovaries after chronic waterborne exposure.

Ecotoxicological studies have indicated the reprotoxicity of uranium (U) in zebrafish, but its molecular mechanisms remain unclear. Due to the non-covalent nature of U-protein complexes, canonical proteomics approaches are often not relevant as they usually use denaturating reagents or solvents. In this study, non-denaturating (ND) methods were used to obtain insight into the nature of U potential targets in ovaries of reproduced and non-reproduced zebrafish after 20 days of exposure to an environmentally relevant U concentration (20 µg L-1). After the ND sample preparation, 1-dimensional (SEC) and 2-dimensional (OGE × SEC) separations followed by ICP-sector-field MS measurements (U, P, Fe, Cu, and Zn) enabled the determination of chemical characteristics (MW, pI) of the metal-protein complexes. Phosphorus and U coelution confirmed the affinity of U for P-containing proteins. In addition, 2D separation allowed the discrimination of Fe-metalloproteins as potential U targets. Finally, 20 protein candidates for U complexation were identified after tryptic digestion conditions by LC-ESI FT MS and a database search. Potential U targets were mainly involved in three biological processes: oxidative stress regulation (SOD, GST), cytoskeleton structure (actin) and embryo early development (vtg, initiation factor).

Quality Evaluation Focusing on Tissue Fractal Dimension and Chemical Changes for Frozen Tilapia with Treatment by Tangerine Peel Extract.

This work aimed to establish an effective approach to evaluate the quality of frozen fish, focusing on changes in fish tissue structure and chemical composition during storage. Fresh tilapia samples were treated by coating with tangerine peel (TP) extract and then stored at -4, -8 and -18 °C, respectively, for 40 days. The frozen fish tissues were analyzed for structural and chemical changes. Fractal dimension, which quantifies the porous structure formed in the tissue samples, texture properties including hardness and springiness, and moisture content and water activity all decreased during the storage, while the extents of lipid oxidation, measured as peroxide value and thiobarbituric acid concentration, and protein degradation, monitored with total volatile basic nitrogen and trichloroacetic acid soluble peptides, increased. The change rates of these parameters decreased with decreasing the storage temperature and by applying TP extract. A model was developed for predicting fractal dimension, which indicated the quality of preserved tilapia and thus can be used to predict the shelf life under different storage temperatures. The results demonstrated that TP extract could extend the shelf life of frozen tilapia by 35-45% by inhibiting changes in tissue structure, moisture loss, lipid oxidation and protein degradation during frozen storage.

Antioxidant activity measurement and potential antioxidant peptides exploration from hydrolysates of novel continuous microwave-assisted enzymolysis of the Scomberomorus niphonius protein.

A novel continuous microwave-assisted enzymatic digestion (cMAED) method is proposed for the digestion of protein from Scomberomorus niphonius to obtain potential antioxidant peptides. In this study, bromelain was found to have a high capacity for the digestion of the Scomberomorus niphonius protein. The following cMAED conditions were investigated: protease species, microwave power, temperature, bromelain content, acidity of the substrate solution, and incubation time. At 400W, 40°C, 1500U·g-1 bromelain, 20% substrate concentration, pH 6.0 and 5min incubation, the degree of hydrolysis and total antioxidant activity of the hydrolysates were 15.86% and 131.49µg·mL-1, respectively. The peptide analyses showed that eight of the potential antioxidant peptide sequences, which ranged from 502.32 to 1080.55Da with 4-10 amino acid residues, had features typical of well-known antioxidant proteins. Thus, the new cMAED method can be useful to obtain potential antioxidant peptides from protein sources, such as Scomberomorus niphonius.

Profiles of gonadotropin-inhibitory hormone and melatonin during the sex change and maturation of cinnamon clownfish, Amphiprion melanopus.

The present study aimed to determine the relationship between melatonin and gonadotropin-inhibitory hormone (GnIH) and their effect on reproduction in cinnamon clownfish, Amphiprion melanopus. Accordingly, we investigated the expression pattern of GnIH, GnIH receptor (GnIH-R), and melatonin receptor (MT-R1) mRNA and protein, as well as the plasma levels of melatonin, during sex change in cinnamon clownfish. We found that GnIH and MT-R1 mRNA and melatonin activity were higher in fish with mature brain than in fish with developing gonads, and using double immunofluorescence staining, we found that both GnIH and MT-R1 proteins were co-expressed in the hypothalamus of cinnamon clownfish. These findings support the hypothesis that melatonin plays an important role in the negative regulation of maturation and GnIH regulation during reproduction.

Resurfaced fluorescent protein as a sensing platform for label-free detection of copper(II) ion and acetylcholinesterase activity.

Protein engineering by resurfacing is an efficient approach to provide new molecular toolkits for biotechnology and bioanalytical chemistry. H39GFP is a new variant of green fluorescent protein (GFP) containing 39 histidine residues in the primary sequence that was developed by protein resurfacing. Herein, taking H39GFP as the signal reporter, a label-free fluorometric sensor for Cu(2+) sensing was developed based on the unique multivalent metal ion-binding property of H39GFP and fluorescence quenching effect of Cu(2+) by electron transfer. The high affinity of H39GFP with Cu(2+) (Kd, 16.2 nM) leads to rapid detection of Cu(2+) in 5 min with a low detection limit (50 nM). Using acetylthiocholine (ATCh) as the substrate, this H39GFP/Cu(2+) complex-based sensor was further applied for the turn-on fluorescence detection of acetylcholinesterase (AChE) activity. The assay was based on the reaction between Cu(2+) and thiocholine, the hydrolysis product of ATCh by AChE. The proposed sensor is highly sensitive (limit of detection (LOD) = 0.015 mU mL(-1)) and is feasible for screening inhibitors of AChE. Furthermore, the practicability of this method was demonstrated by the detection of pesticide residue (carbaryl) in real food samples. Hence, the successful applications of H39GFP in the detection of metal ion and enzyme activity present the prospect of resurfaced proteins as versatile biosensing platforms.

Biochemical characteristics of four marine fish skins in Korea.

In this study, we investigated the biochemical characteristics of the fish skins of four industrial species: olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), sea bass (Lateolabrax maculatus) and red sea bream (Pagrus major). There is high domestic demand in Korea for farming of these fish for human consumption. Crude protein contents in the skin of these fish ranged from 73% to 94% by dry weight; this was in part due to a high content of the structural protein, collagen. Among the four species, olive flounder had the thickest dermal and epidermal layers in the dorsal skin. This species was also associated with the highest extraction ratio of acid-soluble collagen. We also examined whether fish skin could be a cost-effective alternative to current fish meal sources. Our analysis indicates that, when supplemented with additional fish oils and essential amino acids, fish skin is a viable alternative for fish meal formulations.

Taurine supplementation of plant derived protein and n-3 fatty acids are critical for optimal growth and development of cobia, Rachycentron canadum.

We examined growth performance and the lipid content in juvenile cobia, Rachycentron canadum, fed a taurine supplemented (1.5 %), plant protein based diet with two fish oil replacements. The first fish oil replacement was a thraustochytrid meal (TM + SOY) plus soybean oil (~9 % CL) and the second was a canola oil supplemented with the essential fatty acids (EFA) docosahexaenoic acid (DHA) and arachidonic acid (ARA) (~8 % CL). The diet using the thraustochytrid meal plus soybean oil performed equivalently to the fish oil diet; both resulting in significantly higher growth rates, lower feed conversion ratios, and higher survival than the supplemented canola oil diet, even though all three diets were similar in overall energy and met known protein and lipid requirements for cobia. The poor performance of the canola oil diet was attributed to insufficient addition of EFA in the supplemented canola oil source. Increasing levels of EFA in the supplemented canola oil above 0.5 g EFA kg(-1) would likely improve results with cobia. When fish fed either of the fish oil replacement diets were switched to the fish oil control diet, fatty acid profiles of the fillets were observed to transition toward that of the fish oil diet and could be predicted based on a standard dilution model. Based on these findings, a formulated diet for cobia can be produced without fish products providing 100 % survivorship, specific growth rates greater than 2.45 and feed conversion ratios less than 1.5, as long as taurine is added and EFA levels are above 0.5 g EFA kg(-1).

Utilization of seafood processing by-products: medicinal applications.

Large amount of underutilized by-products are generated from the seafood processing plants annually. Consequently, researches have been initiated to investigate those discarded materials and have identified a number of bioactive compounds including bioactive peptides, collagen and gelatin, oligosaccharides, fatty acids, enzymes, calcium, water-soluble minerals, and biopolymers. Bioactive peptides derived from fish by-products have shown various biological activities including antihypertensive and antioxidant activities and hence may be a potential material for biomedical and food industries. Collagen and gelatin are currently used in diverse fields including food, cosmetic, and biomedical industries. Other than that, they are promising drug carriers for the treatment of cancer. Many studies have reported that chitin, chitosan, and their derivatives possess biologically active polysaccharides and hence they are potential agents for many applications. Further, those compounds have also showed potential activities such as antioxidant, antibacterial, antiviral, antihypertensive, anticancer, etc. Hence, seafood by-products are valuable natural resources that show range of functionalities and hence potential materials for biomedical and nutraceutical industries.

Quality of ready to serve tilapia fish curry with PUFA in retortable pouches.

UNLABELLED: Studies on the physical, chemical, and microbiological qualities of fresh tilapia meat revealed its suitability for the preparation of ready to eat fish curry packed in retort pouches. Studies on the fatty acid profile of tilapia meat suggest fortification with polyunsaturated fatty acid (PUFA) to increase the nutritional value. Based on the commercial sterility, sensory evaluation, color, and texture profile analysis F(0) value of 6.94 and cook value of 107.24, with a total process time of 50.24 min at 116 °C was satisfactory for the development of tilapia fish curry in retort pouches. Thermally processed ready to eat south Indian type tilapia fish curry fortified with PUFA was developed and its keeping quality studied at ambient temperature. During storage, a slight increase in the fat content of fish meat was observed, with no significant change in the contents of moisture, protein, and ash. The thiobarbituric acid (TBA) values of fish curry significantly increased during storage. Fish curry fortified with 1% cod liver oil and fish curry without fortification (control) did not show any significant difference in the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during thermal processing and storage. Sensory analysis revealed that fortification of fish curry with cod liver oil had no impact on the quality. Tilapia fish curry processed at 116 °C and F(0) value of 7.0 (with or without fortification of cod liver oil) was fit for consumption, even after a period of 1-y storage in retort pouch. PRACTICAL APPLICATION: Tilapia is a lean variety of fish with white flesh and therefore an ideal choice as raw material for the development of ready to serve fish products such as fish curry in retort pouches for both domestic and international markets. Ready to eat thermal processed (116 °C and F(0) value of 7.0) south Indian type tilapia fish curry enriched with PUFA and packed in retort pouch was acceptable for consumption even after a storage period of 1 y at ambient temperature.

Gel strengthening effect of wood extract on surimi produced from mackerel stored in ice.

The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel (Rastrelliger kanagurta) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously (P < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.

Novel fish hypothalamic neuropeptides stimulate the release of gonadotrophins and growth hormone from the pituitary of sockeye salmon.

We recently identified a cDNA encoding three novel fish hypothalamic neuropeptides, having LPXRF-NH(2) from the goldfish brain. In this study, to clarify the physiological functions of these three LPXRFamide peptides (gfLPXRFa-1, -2, and -3), we analysed the localisation and hypophysiotrophic activity of these peptides using sockeye salmon, Oncorhynchus nerka, in which immunoassay systems for several anterior pituitary hormones have been developed. gfLPXRFa-immunoreactive cell bodies were detected in the nucleus posterioris periventricularis of the hypothalamus and immunoreactive fibres were distributed in various brain regions and the pituitary. We also detected gfLPXRFa-immunoreactivity in the pituitary by competitive enzyme-linked immunosorbent assay combined with reversed-phase HPLC. These three gfLPXRFamide peptides stimulated the release of FSH, LH and GH, but did not affect the release of prolactin (PRL) and somatolactin (SL) from cultured pituitary cells. These results suggest that novel fish hypothalamic LPXR-Famide peptides exist in the brain and pituitary of sockeye salmon and stimulate the release of gonadotrophins and GH from the pituitary.