Habitat use by demersal nekton on the continental shelf in the Benguela ecosystem, southern Africa

Videotapes collected by the research submersible Jago in the Benguela ecosystem during spring 1997 were analyzed to determine demersal nekton assemblage composition, fish behavior, and microscale habitat association, and habitat selection. Demersal fish assemblage diversity was generally low, and their composition was a function of substratum type. Individual species showed an often marked association with either rocky or soft substrata (or both), and a strong or weak selection for the associated biota. Soles and dragonets actively selected areas of bioactive soft substrata, to which they are behaviorally and morphologically adapted. False jacopever were associated with crevices in areas of high-relief rocky substrata. Kingklip are piscivorous and were largely confined to holes at the base of rocks and favored areas without a conspicuous epifauna. Juvenile hake and gobies avoided extremely rocky areas and were largely indifferent to the presence of benthic invertebrates—behavior that is consistent with their planktonic diets. These results represent the first direct observations of demersal nekton in the region and are important because they allow better interpretations of the results of trawl studies

Metal-sensitive and thermostable trypsin from the crevalle jack (Caranx hippos) pyloric caeca: purification and characterization

Background: Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.Results: A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-alpha-benzoyl-(DL)-arginine-p-nitroanilide (BApNA) as substrate. in addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50 degrees C, respectively. After incubation at 50 degrees C for 30 min the enzyme lost only 20% of its activity. K-m, k(cat), and k(cat)/K-m values using BApNA as substrate were 0.689 mM, 6.9 s(-1), and 10 s(-1) mM(-1), respectively. High inhibition of trypsin activity was observed after incubation with Cd2+, Al3+, Zn2+, Cu2+, Pb2+, and Hg2+ at 1 mM, revealing high sensitivity of the enzyme to metal ions.Conclusions: Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.Financiadora de Estudos e Projetos (FINEP/RECARCINE)Petroleo do Brasil S/A (PETROBRAS)Secretaria Especial de Aquicultura e Pesca (SEAP/PR)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao de Apoio a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE)Univ Fed Pernambuco, Lab Enzimol LABENZ, Dept Bioquim CCB, BR-50670910 Recife, PE, BrazilUniv Fed Pernambuco, LIKA, BR-50670910 Recife, PE, BrazilUniversidade Federal de São Paulo, Dept Biofis, Escola Paulista Med, BR-04044020 São Paulo, BrazilUniv Fed Pernambuco, Lab Glicoprot, Dept Bioquim CCB, BR-50670910 Recife, PE, BrazilUniversidade Federal de São Paulo, Dept Biofis, Escola Paulista Med, BR-04044020 São Paulo, BrazilWeb of Scienc

Trypsin purification using magnetic particles of azocasein-iron composite

This work presents an inexpensive, simple and fast procedure to purify trypsin based on affinity binding with ferromagnetic particles of azocasein composite (mAzo). Crude extract was obtained from intestines of fish Nile tilapia (Oreochromis niloticus) homogenized in buffer (01 g tissue/ml). This extract was exposed to 100mg of mAzo and washed to remove unbound proteins by magnetic field. Trypsin was leached off under high ionic strength (3 M NaCl). Preparation was achieved containing specific activity about 60 times higher than that of the crude extract. SDS-PAGE showed that the purified protein had molecular weight (24 kDa) in concordance with the literature for the Nile tilapia trypsin. The mAzo composite can be reused and applied to purify trypsin from other sources.Authors are thankful to CNPq (grant 307273/2013-0) and CAPES (Scholarship to MHMEA) Brazil agencies as well as FCT (Scholarship to SICS and CN) Portugal Agencie

New insights into the impact of polystyrene micro/nanoplastics on the nutritional quality of marine jacopever (Sebastes schlegelii)

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous in the marine environments due to the wide use and mismanagement of plastics. However, the effect of MPs/NPs on the nutrition quality of economic species is poorly understood, and their underlying mechanisms remained unclear. We therefore investigated the impacts of polystyrene MPs/NPs on the nutrition composition of marine jacopever Sebastes schlegelii from the perspective of assimilation and metabolism. Results showed that NPs reduced more nutrition quality than MPs. Despite no notable impact on intestinal microbiota function, MPs/NPs influenced the assimilation of fish through intestinal damage. Furthermore, NPs induced greater damage to hepatocyte metabolism than MPs, caused by hepatocyte uptake through membrane protein pumps/channels and clathrin/caveolin-mediated endocytosis for NPs, while through phagocytosis/pinocytosis for MPs. NPs triggered more cell apoptosis signals in Ferroptosis and FoxO signaling pathways than MPs, destroying mitochondria structure. Compared with MP treatments, a significant upregulation of genes (PRODH and SLC25A25A) associated with the electron transfer chain of mitochondria was detected in the NP treatments, influencing the tricarboxylic acid cycle and interfering with liver metabolism of proteins, fatty acid, glycerol phospholipids, and carbohydrates. This work provides new insights into the potential impacts of MPs/NPs on the quality and safety of seafood.publishedVersio

Video observations on the habitat association of demersal nekton in the midshelf benthic environment off the Orange River, Namibia

A semi-quantitative assessment is made of the animals observed in archived videotapes taken from the research submersible Jago, during diamond mining and exploratory surveys off the mouth of the Orange River on the west coast of southern Africa (28°15´S, 29°11´S) in November 1996. The seabed environment is described and nekton associations with substratum features are identified. The area is characterized by heterogeneity to its physical and biological struture. The variety of observed nekton is low, and communities are dominated by goby Sufflogobius bibarbatus, juvenile hake Merluccius spp. and cuttlefish Sepia spp. (on soft substrata), as well as false jacopever Sebastes capensis and kingklip Genypterus capensis (on rocky substrata)

축∙수산물 중 퀴놀론계, 세팔로스포린계, 트리메토프림 항생제에 대한 동시분석법 개발 및 잔류실태조사

학위논문 (박사)-- 서울대학교 대학원 : 수의과대학 수의학과 수의생리학전공(수의생화학), 2016. 2. 이항.Three reliable analytical methods were developed based on a simple and rapid sample preparation followed by ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) for the determination of 13 quinolones, 9 cephalosporins, and trimethoprim in livestock and marine products (beef, pork, chicken, milk, egg, flatfish, jacopever, common eel, and shrimp). The proposed methods were validated according to the CODEX guidelines and applied in the survey of in a total of 1012 samples of livestock and marine products commercialized in Korea. In the first study, a simple and specific analytical method was developed for the simultaneous determination of 13 quinolones (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, ofloxacin, orbifloxacin, oxolinic acid, pefloxacin, and sarafloxacin) using UPLC-ESI-MS/MS and all results fully complied with CODEX recommendation. Good linearities were achieved and the correlation coefficients were ranged between 0.9992 and 0.9999. The recoveries of 13 quinolones were higher than 80%, the limit of detection (LOD) and limit of quantitation (LOQ) were lower than 0.1 and 0.4 μg/kg, respectively. Besides, the matrix-matched calibration curve and internal standard (IS) played a significant role in compensating for the matrix effects. A survey for 13 quinolones residues was conducted on 310 livestock and marine products. Oxolinic acid, enrofloxacin, and flumequine were the most commonly detected antibiotics. The residues of quinolones were detected on 104 samples (33.5% incidence) but residue levels were below the MRLs. Detected concentrations were 0.1-100.0 μg/kg and the risk value (EDI/ADI, %) were safe levels between 0.0005% and 0.612%. However, pefloxacin was detected in one common eel sample above the legal residue limit and the detected concentration was 62.4 μg/kg. In the second study, a sensitive and reliable method was developed and validated for the simultaneous determination of 9 cephalosporins (cefacetrile, cefazolin, cephapirin, desacetyl cephapirin, cefalexin, cefalonium, cefoperazone, cefuroxime, and cefquinome) and all obtained results were satisfied with CODEX recommendation. The use of UPLC-ESI-MS/MS with polarity switching ionization mode improved the sensitivity and reduced analysis time, allowing the identification and quantification of 9 cephalosporins in 5 min. Because of the matrix effects, matrix matched calibration curves with IS were used for quantification to determine cephalosporin residues in samples. Good linearities were acquired and the LOD and LOQ were lower than 8 and 25 μg/kg, respectively. The survey for the 9 cephalosporins residues was conducted on 333 livestock and marine products. The residues were detected in only 12 livestock products (3.6% incidence) but residue levels were below the MRLs and the detected cephalosporins were cefalonium in beef and cefquinome in milk. Detected concentrations were from 1.10 to 9.77 μg/kg in beef and 7.50 μg/kg in milk. The risk value was very safe level of 0.02% in cephalonium and 0.01% in cefquinome. In the third study, a specific and simple analytical method was developed using UPLC-ESI-MS/MS for the determination of trimethoprim. The sample preparation through the ultrasonic-assisted extraction and SPE clean-up procedure was improved the recovery and reduced the matrix effect. The recoveries were higher than 70% and the LOD and LOQ were lower than 0.3 and 1.0 μg/kg, respectively. The survey for the trimethoprim residue was conducted on 369 livestock and marine products. The residues of trimethoprim were detected in 7 marine products (1.9% incidence) but residue levels were below the MRL. Detected concentrations were 1.17 to 16.43 μg/kg in jacopever, 40.0 μg/kg in flatfish, and 13.3 μg/kg in common eel. The risk value was safe level of 0.13%. In conclusion, the methods developed in this study were more reliable and accurate for screening, quantification, and identification of 13 quinolones, 9 cephalosporins, and trimethoprim residues in livestock and marine products and could be successfully applicable in field samples. The resulting residue level of 13 quinolones, 9 cephalosporins, and trimethoprim appeared to be relatively safe. However, the quinolones and 3rd - & 4th -generation cephalosporins were classified as critically important antimicrobials for human medicine (CIA) and trimethoprim and 1st - & 2nd -generation cephalosporins were classified as highly important (HIA) from World Health Organization (WHO). In addition, quinolones, cephalosporins, and trimethoprim were classified as veterinary critically important antimicrobials (VCIA) from the Office International des Epizooties (OIE). Thus, a strict guideline for the use of antibiotics and continuous survey on antibiotic residues is needed to ensure the safety of animal origin foods. The methods developed in this study will help to implement such guidelines of CODEX on the use of antimicrobials.CHAPTER I Development of multi-residue analytical method for 13 quinolones and application to the residue monitoring in livestock and marine products in Korea 1 ABSTRACT 2 INTRODUCTION 4 MATERIALS AND METHODS 8 RESULTS & DISCUSSION 17 CONCLUSION 29 CHAPTER II Development of multi-residue analytical method for 9 cephalosporins and application to the residue monitoring in livestock and marine products in Korea 56 ABSTRACT 57 INTRODUCTION 59 MATERIALS AND METHODS 62 RESULTS & DISCUSSION 68 CONCLUSION 78 CHAPTER III Development of analytical method for trimethoprim and application to the residue monitoring in livestock and marine products in Korea 98 ABSTRACT 99 INTRODUCTION 100 MATERIALS AND METHODS 103 RESULTS & DISCUSSION 107 CONCLUSION 116 GENERAL CONCLUSION 134 REFERENCES 136 ABSTRACT IN KOREAN 145Docto

Differences in PAR-2 activating potential by king crab (Paralithodes camtschaticus), salmon (Salmo salar), and bovine (Bos taurus) trypsin.

The manuscript version of this article, under a different title, is paper 3 of Anett Kristin Larsen's doctoral thesis which is available in Munin at http://hdl.handle.net/10037/2892Background: Salmon trypsin is shown to increase secretion of the pro-inflammatory cytokine interleukin (IL)-8 from human airway epithelial cells through activation of PAR-2. Secretion of IL-8 induced by king crab trypsin is observed in a different concentration range compared to salmon trypsin, and seems to be only partially related to PAR-2 activation. This report aim to identify differences in the molecular structure of king crab trypsin (Paralithodes camtschaticus) compared to salmon (Salmo salar) and bovine trypsin (Bos taurus) that might influence the ability to activate protease-activated receptor-2 (PAR-2). Results: During purification king crab trypsin displayed stronger binding capacity to the anionic column used in fast protein liquid chromatography compared to fish trypsins, and was identified as a slightly bigger molecule. Measurements of enzymatic activity yielded no obvious differences between the trypsins tested. Molecular modelling showed that king crab trypsin has a large area with strong negative electrostatic potential compared to the smaller negative areas in bovine and salmon trypsins. Bovine and salmon trypsins also displayed areas with strong positive electrostatic potential, a feature lacking in the king crab trypsin. Furthermore we have identified 3 divergent positions (Asp196, Arg244, and Tyr247) located near the substrate binding pocket of king crab trypsin that might affect the binding and cleavage of PAR-2. Conclusion: These preliminary results indicate that electrostatic interactions could be of importance in binding, cleavage and subsequent activation of PAR-2

Calculation of calibration factors from the comparative fishing trial between FRS Africana and RV Dr Fridtjof Nansen

Includes abstract. Includes bibliographical references (leaves 153-157)

The diurnal vertical dynamics of cape hake and their potential prey

The Cape hakes Merluccius capensis and M. paradoxus are dominant predators over the Namibian shelf. They are found in a water column that includes myctophids and other mesopelagic fish, euphausiids andcephalopods. Together with their cohabitant potential prey, hake are known to undertake diurnal vertical migrations, aggregating near the bottom during daylight, but migrating off the bottom at night. An attempt to determine the underlying mechanisms of this diurnal migration by means of underwater acoustics and trawling was made at a single location on the central Namibian shelf at a depth of 350 m during four consecutive days in April 1996. Large M. capensis, 50–75 cm total length, dominated just over the sea bed, whereas 30–40 cm M. paradoxus were most abundant 5–50 m off the bottom, suggesting that the smaller M. paradoxus had to remain higher in the water column to avoid being eaten by the larger M. capensis. Large hake of both species preyed preferentially on fish, whereas the smaller hake preferred euphausiids, although there was some evidence of euphausiid consumption by most hake. There was no distinct daily feeding rhythm in either species of hake, although there was some evidence of evening predation dominating. This may indicate a feeding strategy where vision is not important