The stock structure of turbot was investigated between samples from S-Norway, the Irish Sea and the Kattegat, using 12 microsatellite loci and compared to the turbot caught in Icelandic waters. Highly significant genetic differentiation was observed between samples from Kattegat and other areas. Significant genetic differentiation was also observed between the Irish Sea sample on one hand and Iceland and S-Norway on the other hand. No significant genetic differentiation was observed between Iceland and S-Norway. Otoliths of 25 turbot, age ranging from 3 to 19 years, were subjected to nearly 300 mass spectrometry determinations of stable oxygen and carbon isotopes. Oxygen isotope composition (δ18O) in the otolith samples was used to estimate ambient temperature at time of otolith accretion, and yielded estimated temperatures experienced by the turbot ranging from 3 to 15 °C. Overall, the genetic analysis indicates panmixia between turbot in Icelandic and Norwegian waters. While the extensive migration of larvae between Norway and Iceland is unlikely, passive drift of turbot larva from other areas (e.g. Ireland) cannot be ruled out.
Höfundur: admin
Several bacteriophages that infect different strains of the thermophilic bacterium Rhodothermus marinus were isolated and their infection pattern was studied. One phage, named RM378 was cultivated and characterized. The RM378 genome was also sequenced and analyzed. The phage was grouped as a member of the Myoviridae family with A2 morphology. It had a moderately elongated head, with dimensions of 85 and 95 nm between opposite apices and a 150 nm long tail, attached with a connector to the head. RM378 showed a virulent behavior that followed a lytic cycle of infection. It routinely gave lysates with 1011 pfu/ml, and sometimes reached titers as high as 1013 pfu/ml. The titer remained stable up to 65 °C but the phage lost viability when incubated at higher temperatures. Heating for 30 min at 96 °C lowered the titer by 104. The RM378 genome consisted of ds DNA of 129.908 bp with a GC ratio of 42.0 % and contained about 120 ORFs. A few structural proteins, such as the major head protein corresponding to the gp23 in T4, could be identified. Only 29 gene products as probable homologs to other proteins of known function could be predicted, with most showing only low similarity to known proteins in other bacteriophages. These and other studies based on sequence analysis of a large number of phage genomes showed RM378 to be distantly related to all other known T4-like phages.
A novel and non-ubiquitous thermostable DNA polymerase in Thermus antranikianii was expressed in E. coli, isolated and biochemically characterized. The enzyme here referred to as Thermophi, has a C-terminal polymerase domain and a proofreading 3′→5′ exonuclease domain, but lack the 5′→3′ exonuclease domain. The corresponding gene is apparently only found in some but not all Thermus strains. The initial rate of specific activity of this polymerase on nicked DNA was about 360,000 U/mg protein. The optimum activity was found at 55 °C, pH 8.5 and 1.5 mM Mg+2. The polymerase was stable at 70 °C and lost 50% of its activity after 5 min at 85 °C, but could be stabilized above 80 °C by addition of 0.5 M L-proline. A pronounced strand-displacement activity was indicated by the large amount of DNA produced by the enzyme after an overnight, isothermal incubation in presence of hexamer primers. Both single and double stranded DNA was isothermally amplified by the enzyme. The amplified DNA was large and apparently highly branched material and composed of both single and double stranded DNA. The produced material could be partly digested by T7 enonuclease I but it was difficult to cut with common restriction enzymes. Amplification of selected genes from dilute samples was successfully demonstrated with the human β-actin gene. Good amplification was also found with 5 microsatellite markers from salmon DNA. Thermophi amplifies DNA by orders of magnitude but upon extended reaction time the DNA becomes very large and highly branched. It is composed of both single and double strands and then correctly amplified sequences only represent about 10-20% of the total DNA, and long stretches of TATATA repeats frequently occur in the amplified DNA.
Increasing consumer demand for seafood, combined with concern over the health of our oceans, has led to many initiatives aimed at tackling destructive fishing practices and promoting the sustainability of fisheries. An important global threat to sustainable fisheries is Illegal, Unreported and Unregulated (IUU) fishing, and there is now an increased emphasis on the use of trade measures to prevent IUU-sourced fish and fish products from entering the international market. Initiatives encompass new legislation in the European Union requiring the inclusion of species names on catch labels throughout the distribution chain. Such certification measures do not, however, guarantee accuracy of species designation. Using two DNA-based methods to compare species descriptions with molecular ID, we examined 386 samples of white fish, or products labelled as primarily containing white fish, from major UK supermarket chains. Species specific real-time PCR probes were used for cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to provide a highly sensitive and species-specific test for the major species of white fish sold in the UK. Additionally, fish-specific primers were used to sequence the forensically validated barcoding gene, mitochondrial cytochrome oxidase I (COI). Overall levels of congruence between product label and genetic species identification were high, with 94.34% of samples correctly labelled, though a significant proportion in terms of potential volume, were mislabelled. Substitution was usually for a cheaper alternative and, in one case, extended to a tropical species. To our knowledge, this is the first published study encompassing a large-scale assessment of UK retailers, and if representative, indicates a potentially significant incidence of incorrect product designation.
Value added products such as fish protein hydrolysates (FPH) can be produced from fish by-products. Lipid oxidation and bad taste are the major challenge in the commercialization of bioactive FPH. The aim of this research was to study the production of high quality FPH from fish by-products prepared by enzymatic hydrolysis using a natural antioxidant extracted from the Icelandic brown algae Fucus vesiculosus (Fv). FPH were produced from cod waste material; i.e. cod bone mince, in the absence and presence of an Fv extract (Fv-e). Oxidation during the FPH production was evaluated (lipid hydroperoxides and thiobarbituric acid reactive substances). The FPH were sensory analyzed (generic descriptive analysis) and in vitro antioxidant activity was evaluated. Results show that Fv–e contributed to better tasting FPH with regard to bitter, soap, fish oil and rancidity taste. Results from the oxidation and antioxidant activity assays indicated a protecting effect of Fv-e during processing.
Fish protein hydrolysates (FPH) have many desirable properties, however heating and shifts in pH can cause oxidation during enzymatic hydrolysis. The objective was to investigate oxidative processes during enzymatic hydrolysis of fish protein and the impact of oxidation on the antioxidant and immunomodulating ability of FPH. Protease P “Amano” 6 was used to hydrolyze cod protein in the presence and absence of pro-oxidants at pH 8 and 36 °C to achieve 20% degree of hydrolysis. Results from thiobarbituric acid reactive substances (TBARS) and sensory analysis indicate that oxidation can develop rapidly during hydrolysis. A cellular antioxidant assay using a HepG2 cell model indicated a negative impact of oxidation products on antioxidant properties of the FPH while results obtained in chemical assays showed a negligible impact. Results from a dendritic cell model indicating that oxidation products may affect anti-inflammatory activity in the body. This study provides important information regarding bioactive FPH.
Agriculture and agro-industry are important sectors in the economies of most developing countries, where they provide the main source of livelihoods for the majority of the poor. The lack of a sustainable supply of affordable energy is a major constraint to the development of these sectors in developing countries. Traditionally, geothermal energy has been utilized mainly to generate electricity; however, it can be harnessed for other important uses in agriculture and agro-industry. Developing countries endowed with this renewable energy source have ample potential to use it in advancing their agriculture and agro-industry sectors. This book reviews the use of geothermal energy in agriculture and agro-industry around the world. With a simple format and copious illustrations and models, the book is accessible to a wide range of interested readers, including those with no technical background. It shows that geothermal resources have the potential to provide long-term, secure energy for the agriculture and food industry in both developed and developing countries. Constraints and challenges that should be addressed before this potential can be fully achieved are also discussed.
Antioxidant and sensory properties of Nile tilapia protein hydrolysates prepared by one- and two-step hydrolysis using commercial proteases were investigated. Hydrolysates prepared using single protease including Alcalase (HA), Flavourzyme (HF), Protamex (HPr) and papain (HPa) had increases in antioxidant activities as the degree of hydrolysis (DH) increased up to 40 % (P < 0.05). Amongst all hydrolysates, HA having 40 % DH showed the highest antioxidant activities. When HA was further hydrolysed by papain, the resulting hydrolysate (HAPa) exhibited the highest antioxidant activities for all assays tested (P < 0.05). ABTS radical scavenging activity and metal chelating of HAPa generally remained constant in a wide pH range (1–11) and during heating at 30–100 °C. Both activities increased in the simulated gastrointestinal tract model system, especially in intestine condition. HAPa (100–1,000 ppm) could retard lipid oxidation in β-carotene-linoleate and lecithin-liposome model systems in a dose dependent manner. Peptides in both HA and HAPa with molecular weight of 513 Da and 1,484 Da possessed the strongest ABTS radical scavenging activity and metal chelating activity, respectively. The amino acid profile of both HA and HAPa contained a high amount of hydrophobic amino acids (38.26–38.85 %) and had glutamic acid/glutamine, lysine and aspartic acid/asparagine as the dominant amino acids. However, HAPa showed a higher acceptability than did HA, owing to the lower bitterness. Therefore, the use of Alcalase in combination with papain for hydrolysis of protein isolate rendered the hydrolysate with antioxidant properties and reduced bitterness, which could serve as the functional supplement.
Antioxidant activities of protein hydrolysate prepared from Nile tilapia protein isolate using Alcalase (HA), Alcalase followed by papain (HAPa) and their Sephadex G-25 fractions (FHA and FHAPa) were investigated in both chemical and cellular based models. Amongst all samples, FHAPa showed the highest chemical antioxidant activities, however it had no metal chelation activity. Cellular antioxidant ability of HA, HAPa and their fractions against H2O2 and AAPH induced oxidative damage of HepG2 cell and DNA were tested. When cells were pretreated with all hydrolysates or fractions at different concentrations (0.5–2 mg/mL) in the absence and presence of 50 μM Trolox, cell viability was in the range of 91.10–111.40 %. However, no difference in cell viability was observed among samples having various concentrations (P > 0.05). Cell reactive oxygen species (ROS) generation as mediated by H2O2 and AAPH decreased with treatment of hydrolysates or their fractions, especially in combination with 50 μM Trolox. FHAPa effectively inhibited H2O2 and peroxyl radical induced DNA scission in a dose dependent manner. Therefore, Nile tilapia protein hydrolysates could serve as a functional food ingredient.
In northern Europe a number of fish products are prepared in such a way that biochemical and microbial action can take place. These are complex processes for which there are few available scientific studies. This article covers the origin, manufacturing, characteristics, and consumption of traditional fermented fish products, including surströmming from Sweden, rakfisk from Norway, hákarl from Iceland, and the barrel-salted herring that was commonly produced in most of northern Europe.