Marine Protein Research Articles

Dietary Reconstruction and Reservoir Correction of 14C Dates on Bones from Pagan and Early Christian Graves in Iceland

In this study, δ13C and δ15N of bone samples from 83 skeletons (79 humans, 2 horses, and 2 dogs) excavated from pagan and early Christian graves from 21 localities in Iceland are used to reconstruct diet of the early settlers in Iceland and possible differences in diet depending on the distance between the excavation site and the seashore. We have radiocarbon dated 47 of these skeletons and used the carbon isotopic composition (δ13C) to estimate and correct for the marine reservoir effect (the 14C difference between terrestrial and mixed marine organisms). The reservoir-corrected ages lie in the range of AD 780–1270 (68.2% probability). Reservoir age corrections were checked by comparing 14C dates of a horse (terrestrial diet), a dog (highly marine diet), and a human (mixed diet) from the same burial. The range in measured marine protein percentage in individual diet is from about 10% up to 55%, mostly depending on the geographical position (distance from the sea) of the excavation site. We had access to the skeleton (AAR-5908) of the Skálholt bishop Páll Jónsson whose remains are enshrined at the Episcopal residence in Skálholt, southern Iceland. According to written sources, the bishop died in AD 1211. Using our dietary reconstruction, his bones were about 17% marine, which is within the range of human skeletons from the same area, and the reservoir-corrected calibrated 14C age of the skeleton is in accord with the historical date.

Dietary Reconstruction of the Okhotsk Culture of Hokkaido, Japan, Based on Nitrogen Composition of Amino Acids: Implications for Correction of 14C Marine Reservoir Effects on Human Bones

The relative contribution of marine-derived carbon in the ancient diet is essential for correcting the marine reservoir effect on the radiocarbon age of archaeological human remains. In this study, we evaluated the marine protein consumption of 3 human populations from the Okhotsk culture (about AD 550–1200) in Hokkaido, Japan, based on stable carbon and nitrogen isotopic compositions in bulk bone collagen as well as the nitrogen isotopic composition of glutamic acid and phenylalanine. Despite the similarity of carbon and nitrogen isotopic composition of bulk collagens, nitrogen isotopic composition of their constituent amino acids suggests differences in fur seal contributions among northern Hokkaido (0–24% for Kafukai 1, 0–10% for Hamanaka 2) and eastern Hokkaido (78–80% for Moyoro) populations. It suggests that nitrogen composition of glutamic acid and phenylalanine could provide a detailed picture of ancient human subsistence.

Kvinnan från Österöd

In this paper we describe the find of an early Mesolithic skeleton from Österöd, Bro parish, in central Bohuslän. The skeleton was originally found in 1903 by diggers in a shell bank, but was only recovered in 1933 by Johan Alin. In 2007, 14C analysis of a tooth produced the date 9025±65 BP uncalibrated, making the skeleton one of the oldest known from Scandinavia. Osteological determinations show that the bones are from a woman of old age, at least 60 and probably 84–88 years old. Her stature can be estimated to about 170 cm. Although the bones are fragmented, all body parts are represented, and the body was most likely intact when interred. We interpret the find as a grave, possibly in a sitting position. Interestingly, the δ13C value of -18.0 ‰ indicates only a moderate intake of marine protein, in spite of the location of the site in a highly marine environment.

Late Holocene Dietary Change in the San Francisco Bay Area

Scholars of California prehistory continue to debate the importance of different food resources to the native diet during the late Holocene. Resource intensification models for central California predict temporal declines in the abundance of large game relative to smaller fauna, as well as a shift towards greater use of vegetal foods. These changes are commonly linked to human-driven resource depression and overpopulation, although climatic factors may also have played a role. This study uses data from stable carbon and nitrogen isotopes of human bone to evaluate evidence of paleodietary change among late Holocene human populations (ca. 4950-200 cal B.P.) from the eastern shore of San Francisco Bay, California. Carbon and nitrogen isotope values of bone collagen demonstrate significant temporal variation and indicate a shift in emphasis from high trophic-level marine protein toward a greater emphasis on terrestrial resources and lower trophic-level marine foods. Carbon isotope values of bone apatite provide additional information not recorded in bone collagen, and suggest an increased emphasis on vegetal resources during the latter part of the prehistoric sequence (after ca. 2150 cal B.P.). Alternatively, the isotopic data presented here could provide evidence for regionally specific diets or variation due to human population movement throughout the San Francisco Bay area.

Reconstructing Late Bronze Age diet in mainland Greece using stable isotope analysis

The Late Bronze Age is a period of great importance in prehistoric Greece, due to the rise of the Mycenaean and Minoan civilizations. Settlements, palatial complexes and cemeteries have been excavated whilst a plethora of findings among which wall paintings and artifacts provided a large amount of information regarding the period. In this paper we examine the sources of dietary protein of four populations, from mainland Greece, in light of documentary and archaeological evidence in an effort to identify dietary trends within and between groups that reflect everyday behavior. These are being studied with the aid of biomolecular archaeology using stable isotope analysis in human and faunal remains. Isotopic data to date suggests a rather homogeneous diet mainly based on C 3 plant and animal protein. There are no individuals with δ 13C and δ 15N values that could represent important marine protein intake, despite proximity to the Aegean Sea.

Dietary Protein Source and Level Affects Growth in Neon Tetras

AbstractNutritional studies for aquarium fishes like the neon tetra Paracheirodon innesi are sparse in comparison with those for food fish. To determine the optimum dietary protein level and source for growth of neon tetras, diets were formulated to contain 25, 35, 45, and 55% dietary protein from either marine animal protein or plant protein sources in a 4 × 2 factorial treatment design. Neon tetras (initial weight, approximately 0.12 g) were reared in 5‐L fiberglass tanks (25 fish/tank, 3 tanks/diet) in a freshwater recirculating system. Fish were hand‐fed the experimental diets three times per day for 12 weeks. Average weight gain of neon tetras fed diets with marine protein sources was significantly higher than that for fish fed diets based on plant proteins. Fish fed diets containing 45% or 55% crude protein had significantly greater weight gain than did fish fed 25% crude protein from either protein source. Fish fed 25% crude protein from either source had a significantly higher feed conversion ratio than did those fed 45% or 55% crude protein. Survival ranged from 71% to 84% and was not significantly altered by dietary protein source or level. No significant interactions between dietary protein source and level were found for any of the response variables. As the price of fish meal continues to increase, the formulations of feeds for food fish will probably contain lower amounts of fish meal and higher amounts of plant protein products. If a similar trend occurs for ornamental fish diets, further refinement of nutritional requirements and assessment of palatability of feed ingredients for neon tetras and other aquarium species will be required.

Resolving the bulk δ 15N values of ancient human and animal bone collagen via compound-specific nitrogen isotope analysis of constituent amino acids

Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ 15N values is necessary. Determinations of δ 15N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ 15N values according to their biosynthetic origins. A range of collagen isolates from archaeological faunal and human bone ( n = 12 and 11, respectively), representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The collagens were hydrolysed and δ 15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ 15N values reveals a 2‰ offset from bulk collagen δ 15N values which is attributable to the δ 15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). The δ 15N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ 15N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The similarity in the δ 15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ 15N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ 15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ 15N Glu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ 15N Glu-Phe values. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ 15N values with Δ 15N Glu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ 15N Glu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets.

Harvesting the Seashores in the Late Mesolithic of Northwestern Europe: A View From Brittany

The shell middens of Brittany provide the last evidence of a Mesolithic way of life along the French Atlantic facade. This is partly a result of Holocene marine transgressions that prevent easy access to earlier coastal settlements. Nevertheless, the dependence on the sea seen in the Late Mesolithic seems to be a consequence of a long-established exploitation system. Stable carbon and nitrogen isotope signatures in human bone reflect a dominance of marine protein, while the zooarchaeological components of shell middens show a high species richness of exploited marine resources. Paleoenvironmental reconstruction suggests that more or less the whole range of resources exploited was accessible in the immediate vicinity of the sites. Seasonal aspects of the utilised and potentially available subsistence resources, along with stable isotope and lithic data, raise the possibility of restricted mobility for these populations, within relatively limited territories. The impression of extreme dependence of these coastal populations on the seashore might have been a key factor in their final disappearance, whether this is viewed as replacement or acculturation. Indeed, the Mesolithic communities of Brittany could have been caught between rising sea-levels and the arrival of Neolithic communities from the east and the south.

Isotope analysis of human and animal diets from the Hanamiai archaeological site (French Polynesia)

AbstractWe report the first palaeodietary stable isotope study of humans and animals from an East Polynesian archaeological site. The Hanamiai Dune in the Marquesas Islands of French Polynesia has a long stratigraphy (ca. 1025 AD to 1850 AD). We obtained carbon and nitrogen isotope values for a wide range of terrestrial and marine species from different cultural layers. We also analyzed four human teeth representing four different individuals. Pigs, rats and dogs from the initial occupation phases had isotope signatures indicating marine protein consumption, probably linked to the consumption, and subsequent extinction, of indigenous seabirds. We found evidence of different pig husbandry practices, with some pigs having an almost entirely marine diet. Humans, surprisingly, did not have a mainly marine diet but likely derived the majority of their protein from eating terrestrial mammals such as pigs, as well as perhaps dogs and rats.

Antioxidant properties of a new antioxidative peptide from algae protein waste hydrolysate in different oxidation systems

Microalgae have been a popular edible food, but there are no known reports on the antioxidative peptides derived from microalgae. The algae protein waste, which is normally discarded as animal feed, is a by-product during production of algae essence from microalgae, Chlorella vulgaris. Algae protein waste was hydrolyzed using pepsin, and a potent antioxidative peptide of VECYGPNRPQF was separated and isolated. The peptide could efficiently quench a variety of free radicals, including hydroxyl radical, superoxide radical, peroxyl radical, DPPH radical and ABTS radicals, and performed more efficiently than that observed for BHT, Trolox and peptides from marine protein sources in most cases. The purified peptide also has significant protective effects on DNA and prevents cellular damage caused by hydroxyl radicals. In addition, the peptide has gastrointestinal enzyme-resistance and no cytotoxicity observed in human lung fibroblasts cell lines (WI-38) in vitro. These results demonstrate that inexpensive algae protein waste could be a new alternative to produce antioxidative peptides.

The water soluble fraction in fish meal (stickwater) stimulates growth in Atlantic salmon ( Salmo salar L.) given high plant protein diets

In this study, increasing levels of stickwater (SW) separated during the fish meal production process were added back to produce 5 experimental fish meals. Five experimental diets were prepared which consisted of 50 g commercial fish meal and 50 g of the different experimental fish meals with graded inclusion levels of SW kg − 1 diet. The remaining dietary protein sources consisted of a mixture of plant protein sources (soy protein concentrate; 215 g kg − 1 diet, corn gluten; 215 g kg − 1 diet; field beans 140 g kg − 1 diet; wheat gluten 55 g kg − 1 diet) giving 17% of the total dietary protein from marine sources. All the experimental diets were isonitrogenous, isolipidic and isoenergetic. Two more low fish meal diets were prepared containing the low (permeate) or high (retentate) molecular weight fraction of fractionated and ultrafiltrated SW. A control diet containing 300 g commercial fish meal kg − 1 diet was prepared. The diets were fed to 8 triplicate groups of salmon (initial body weight 137 g) for 74 days. Fish growth was positively affected by the increasing inclusion level of SW in the low fish meal diets. The low fish meal diets that were supplemented with SW performed the same, both in terms of growth and feed utilization, as the control diet. The growth parameters were also positively correlated to the dietary levels of taurine and hydroxyproline but it is not known if this is because of taurine and hydroxyproline themselves or if taurine and hydroxyproline are indicators for other functional water soluble components present in the marine raw materials. No significant differences were found in feed intake or feed efficiency, nor was there any difference in ADC of protein, lipid, gross energy or phosphorus (P) among the diets containing the experimental fish meals, except for the control diet which had a lower ADC of protein compared to the high plant protein diets. Whole body proximate composition and total and soluble P content of fish were not affected by the inclusion level of SW in the diets. Significant effects were identified in the free amino acid profile in the fillet of fish fed the different experimental diets. The present work gives further evidence for the importance of marine water-soluble fractions and small marine water-soluble components in high plant protein diets for salmon. The present results may be a significant contribution in explaining why marine protein sources are important in feed for carnivorous fish species. By the addition of SW to the diets higher flexibility in the choice of protein sources may be obtained.

Stable isotope evidence of human diet at the Nukdo shell midden site, South Korea

Carbon and nitrogen stable isotope analysis was undertaken on bone collagen extracted from archaeological human ( n = 48) and animal ( n = 45) skeletons from the Nukdo site, Location I C, South Korea. This shell midden and grave site is dated from the late Mumun (550–300 BC) to early Iron Age (300 BC-1 AD) periods. The herbivorous mammals fell within the range of C 3 consumers, with average values of δ 13C = −21.0 ± 0.5‰ and δ 15N = 3.6 ± 0.5‰ for deer ( n = 16) and δ 13C = −20.6 ± 0.5‰ and δ 15N = 4.5 ± 2.0‰ for wild boar ( n = 17). Humans from this site averaged δ 13C = −18.3 ± 0.4‰ and δ 15N = 11.2 ± 0.7‰ for adults ( n = 15) and δ 13C = −18.7 ± 0.7‰ and δ 15N = 12.5 ± 1.1‰ for juveniles ( n = 33). These δ 13C values indicate that there was no significant input of C 4 plants in the human diets and this may be associated with the spread of rice agriculture in the Mumun period. Human bone collagen δ 13C and δ 15N values indicate that there was some consumption of marine foods, although the main protein sources were from terrestrial foods. The isotope data demonstrate that the humans at Nukdo had mixed diets that included marine and terrestrial protein, including C 3 plants such as rice. Finally, the isotope results from the juveniles indicate that weaning occurred before the age of 1.5 years in this period.

Inkjet printing of bioadhesives

Over the past century, synthetic adhesives have largely displaced their natural counterparts in medical applications. However, rising concerns over the environmental and toxicological effects of the solvents, monomers, and additives used in synthetic adhesives have recently led the scientific community to seek natural substitutes. Marine mussel adhesive protein is a formaldehyde-free natural adhesive that demonstrates excellent adhesion to several classes of materials, including glasses, metals, metal oxides, and polymers. In this study, we have demonstrated computer aided design (CAD) patterning of various biological adhesives using piezoelectric inkjet technology. A MEMS-based piezoelectric actuator was used to control the flow of the mussel adhesive protein solution through the ink jet nozzles. Fourier transform infrared spectroscopy (FTIR), microscopy, and adhesion studies were performed to examine the chemical, structural, and functional properties of these patterns, respectively. FTIR revealed the piezoelectric inkjet technology technique to be nondestructive. Atomic force microscopy was used to determine the extent of chelation caused by Fe(III). The adhesive strength in these materials was correlated with the extent of chelation by Fe(III). Piezoelectric inkjet printing of naturally-derived biological adhesives may overcome several problems associated with conventional tissue bonding materials. This technique may significantly improve wound repair in next generation eye repair, fracture fixation, wound closure, and drug delivery devices.

Effects of a high plant protein diet on the somatotropic system and cholecystokinin in Atlantic salmon ( Salmo salar L.)

To investigate the endocrine signalling from dietary plant protein on somatotropic system and gastrointestinal hormone cholecystokinin (CCK), two iso-amino acid diets based on either high plant or high fish meal protein were fed to Atlantic salmon. Salmon with an average starting weight of 641 ± 23 g ( N = 180), were fed a fish meal (FM) based diet (containing 40% FM) or diets mainly consisting of blended plant proteins (PP) containing only 13% marine protein, of which only 5% was FM for 3 months. mRNA levels of target genes GH, GH-R, IGF-I, IGF-II, IGFBP-1, IGF-IR in addition to CCK-L , were studied in brain, hepatic tissue and fast muscle, and circulating levels of IGF-I in plasma of Atlantic salmon were measured. We detected reduced feed intake resulting in lower growth, weight gain and muscle protein accretion in salmon fed plant protein compared to a diet based on fish meal. There were no significant effects on the regulation of the target genes in brain or in hepatic tissues, but a trend of down-regulation of IGF-I was detected in fast muscle. Lower feed intake, and therefore lower intake of the indispensable amino acids, may have resulted in lower pituitary GH and lower IGF-I mRNA levels in muscle tissues. This, together with higher protein catabolism, may be the main cause of the reduced growth of salmon fed plant protein diet. There were no signalling effects detected either by the minor differences of the diets on mRNA levels of GH, GH-R, IGF-IR, IGF-II, IGFBP-1, CCK or plasma protein IGF-I.

The study on the immunomodulating effect of marine protein peptides in mice

To observe the effects of marine protein peptide (MPP) on immunomodulating in mice and its possible mechanism. Female ICR mice (6-8 weeks old) were administered the MPP for 4 weeks with the dose of 0.22 g/kgBW, 0.45 g/kgBW and 1.35 g/kgBW. Spleen and thymus were weighted and cell-mediated immune functions, humoral immune functions, phagocytic functions of mononuclear phagocyte, NK cell activity assays, the T cell subpopulation of the spleen tissue by the flow cytometer and the concentrations of cytokines in serum by cytometric bead array were examined. The capacity of lymphocyte proliferation induced by Con A (0.33 +/- 0.21), DTH response (0.36 +/- 0.11) mm in MPP 0.22 g/kgBW group were significantly increased in comparison with these values in control group (0.15 +/- 0.10) and (0.21 +/- 0.10)mm, respectively, P < 0.05. IgM-PFC number of MPP 0.22 g/kgBW group (1.64 +/- 0.06), 0.45 g/kgBW group (1.59 +/- 0.05) and 1.35 g/kgBW group (1.56 +/- 0.10) were higher than those in control group (1.38 +/- 0.10), P < 0.01; and the level of serum HC50 of MPP 0.22 g/kgBW group (141.00 +/- 23.00) and 0.45 g/kgBW group (130.40 +/- 33.20) were greater than the control (100.30 +/- 19.40) , P < 0.01. The activity of NK cells in MPP 0.22 g/kgBW group (1.672 +/- 0.142) was significantly elevated in comparison with this value in control group (1.392 +/- 0.182), P < 0.05. The percentage of CD4 T helper (Th) cell in spleen of MPP 0.22 g/kgBW group (32.84 +/- 3.776)% and 0.45 g/kgBW group (32.42 +/- 3.507) % was higher than those in control group (25.06 +/- 0.354) %, P < 0.05. The concentrations of IL-2 in serum of MPP 0.22 g/kgBW group 181.06 pg/ml, 0.45 g/kgBW group 94.84 pg/ml and 1.35 g/kgBW group 102.61 pg/ml were higher than those in control group 0.50 pg/ml, P < 0.05; and the level of IL-5 of MPP 0.22 g/kgBW group (38.31) pg/ml was greater than the control 0.50 pg/ml, P < 0.05. Nevertheless, no obvious effects on weight increasing, the ratio of immune organ and body weight and phagocytosis capacity were observed in our study. MPP could improve the immune functions in mice, and might be by the mechanism of enhancing the function of Th cells stimulating the secretion of Th1 and Th2 type cell cytokines.

Diet and diversity at later medieval fishergate: The isotopic evidence

We present the results of stable carbon and nitrogen isotope analysis of bone collagen for 155 individuals buried at the Later Medieval (13th to early 16th century AD) Gilbertine priory of St. Andrew, Fishergate in the city of York (UK). The data show significant variation in the consumption of marine foods between males and females as well as between individuals buried in different areas of the priory. Specifically, individuals from the crossing of the church and the cloister garth had consumed significantly less marine protein than those from other locations. Isotope data for four individuals diagnosed with diffuse idiopathic skeletal hyperostosis (DISH) are consistent with a diet rich in animal protein. We also observe that isotopic signals of individuals with perimortem sharp force trauma are unusual in the context of the Fishergate dataset. We discuss possible explanations for these patterns and suggest that there may have been a specialist hospital or a local tradition of burying victims of violent conflict at the priory. The results demonstrate how the integration of archaeological, osteological, and isotopic data can provide novel information about Medieval burial and society.

A simple carbon isotope model for reconstructing prehistoric human diet

A compilation of experimental animal data shows that neither delta13C(collagen) nor delta13C(apatite) nor Delta13C(CO-AP) indicate diagnostic reconstructions of diet, diet energy and diet protein. In contrast, plots of delta13C(collagen) against delta13C(apatite) provide a model of three regression lines (C3, C4, and marine diet protein) where position on each line indicates the energy source (C3, C4, or mixed). Neither body size nor trophic position appears to affect these relationships. Modern free-ranging, terrestrial fauna do not fit the model perhaps because they, unlike the experimental fauna, mainly use fermentation rather than digestion during energy metabolism. Archaeological humans fall as expected based on associated floral and faunal evidence. Foraging people plot at positions expected from associated C3 fauna and plants. Those from Cahokia plot, as expected, from associated deer, nuts, and maize whereas people from nearby smaller sites plot in positions consistent with eating more fish. Agriculturists from Ontario and Grasshopper Pueblo plot consistent with dependence on fish by the former and on turkeys by the latter. In Tierra del Fuego, people from interior regions ate more terrestrial fauna, as suggested by ethnohistoric reports, than did people from the coast. In the Southwestern Cape in South Africa individuals late in the sequence have pure C3 diets whereas ones early in the sequence ate marine protein as suggested by independent archaeological evidence. People on San Nicolas Island depended on C4 plants in contrast to other islands off California's coast. This simple model provides more detailed and precise dietary information than do individual isotopic measures.

Accumulation and elimination of methylmercury in Atlantic cod ( Gadus morhua L.) following dietary exposure

Methylmercury is known to bioaccumulate and biomagnify up the marine food chain. Fish from high levels of the marine food chain may contain relatively high concentrations of mercury, and most (>70%) of the mercury found in muscle is methylmercury. In aquaculture, marine protein (mainly fishmeal) is the dominant source of methylmercury, and this raises some concern with regards to fish welfare and consumer safety. A dietary exposure study, including a depuration period, was carried out in order to study the accumulation and elimination of methylmercury in Atlantic cod ( Gadus morhua L.), and to estimate the transfer of methylmercury from feed to fish. Fish were sampled throughout a three month exposure period and a three month depuration period. Muscle samples were fractionated into a protein and a lipid fraction by lipid extraction using methanol and chloroform. Mercury and methylmercury were determined by inductively coupled plasma mass spectrometry (ICPMS) and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS), respectively. A continuous accumulation of methylmercury, after a lag period of 10 days, was observed in muscle tissue during the three months exposure to methylmercury (0.95 ± 0.03 μg Hg/g feed, n = 6). After three months, the final concentration in muscle was 0.38 ± 0.04 μg Hg/g ww ( n = 6), where methylmercury constituted 90–95% of the mercury present. The elimination of methylmercury from muscle was slow and incomplete (within the three months of depuration) with an estimated elimination half-life ( t 1 / 2 ) of 377 days. The transfer of methylmercury from feed to Atlantic cod, described by the estimated absorption efficiency, was 38%. In muscle more than 99% of the mercury was found in the protein fraction. These results suggest that Atlantic cod readily takes up dietary methylmercury, which is efficiently accumulated into muscle, where it is incorporated into larger peptides or proteins. Comparable results were found for Atlantic salmon ( Salmo salar L.). After three months of exposure to dietary methylmercury the final concentration in muscle was 0.33 ± 0.01 μg Hg/g ww ( n = 3), where nearly all (>99%) mercury was found in the protein fraction. This further supports that methylmercury is accumulated in fish muscle, where it is incorporated into larger peptides or proteins.

Co-polypeptides of 3,4-dihydroxyphenylalanine and l-lysine to mimic marine adhesive protein

Co-polypeptides containing 3,4-dihydroxyphenylalanine (DOPA) and l-lysine were synthesized to mimic the marine adhesive proteins through ring-opening polymerizations. The effects of composition, molecular weight, and curing agents on the adhesive properties, swelling, and degradation behavior of synthetic polypeptide were investigated. Ferric ion was introduced to the system to optimize both adhesive strength and water resistance, simulating the specificity of metal-mediated cross-linking of the marine mussel adhesives. The polypeptide was used to bond on porcine skin and porcine bone in vitro to evaluate the adhesive properties. Furthermore, outcomes of the cell culture of both co-polypeptide and co-polypeptide-modified ethylene vinyl acetate (EVA) demonstrated good cell affinity, which would provide basic data for the application of the co-polypeptide in the biomaterial field.

High throughput and rapid screening of marine protein hydrolysates enriched in peptides with angiotensin-I-converting enzyme inhibitory activity by capillary electrophoresis

Twelve kinds of marine protein materials, including fish, shrimp, seashell, algae and seafood wastes were selected for the hydrolysis using four different proteases. The IC 50 values for angiotensin-converting enzyme (ACE) inhibitory activity of 48 hydrolysates were rapidly determined by capillary electrophoresis (CE). The values ranged from 0.17 to 501.7 mg/ml, and were affected by both the marine protein resources and the selected proteases. Hydrolysates of the lowest IC 50 values were from shrimp ( Acetes chinensis), shark meat, mackerel bone, Polysiphonia urceolata and Spirulina platensis, indicating these five kinds of marine food proteins contained beneficial materials for the production of ACE inhibitory peptides by proteolysis. The hydrolysates obtained using proteases Protamex and SM98011 had lower IC 50 values, showing these two proteases were superior to others. The CE method achieved the same sensitivity as the high performance liquid chromatography (HPLC) method. However, the CE method was faster and, as a result, more economical. Therefore, CE had potential for rapid screening of marine protein hydrolysates enriched in ACE inhibitory peptides.