Replacement of high-value fish species with cheaper varieties or mislabelling of food unfit for human con-sumption is a global problem violating both consumers' rights and safety. For... Show moreReplacement of high-value fish species with cheaper varieties or mislabelling of food unfit for human con-sumption is a global problem violating both consumers' rights and safety. For distinguishing fish species in pure samples, DNA approaches are available; however, authentication and quantification of fish species in mixtures remains a challenge. In the present study, a novel high-throughput shotgun DNA sequencing approach applying masked reference libraries was developed and used for authentication and abundance calculations of fish species in mixed samples. Results demonstrate that the analytical protocol presented here can discriminate and predict relative abundances of different fish species in mixed samples with high accuracy. In addition to DNA analyses, shotgun proteomics tools based on direct spectra comparisons were employed on the same mixture. Similar to the DNA approach, the identification of individual fish species and the estimation of their respective relative abundances in a mixed sample also were feasible. Furthermore, the data obtained indicated that DNA sequencing using masked libraries predicted species-composition of the fish mixture with higher specificity, while at a taxonomic family level, relative abundances of the different species in the fish mixture were predicted with slightly higher accuracy using proteomics tools. Taken together, the results demonstrate that both DNA and protein-based approaches presented here can be used to efficiently tackle current challenges in feed and food authentication analyses. Show less
Anthropogenic noise has been shown to affect marine animals in various ways, this may have fitness consequences at individual and population level. This thesis aims to increase insight into the... Show moreAnthropogenic noise has been shown to affect marine animals in various ways, this may have fitness consequences at individual and population level. This thesis aims to increase insight into the quantification of sound-induced behavioural responses that are relevant to fitness, and into factors that modulate the responses. I addressed both knowledge gaps using captive and field studies on marine animals from multiple trophic levels. For the quantification of behavioural responses relevant to fitness, I examined the changes in time budgets of Atlantic cod in a net pen and basin in response to sound (chapter 2 and 3). To increase insight into factors that modulate sound impact, I examined the effect of various acoustic characteristics of sound stimuli and the environment on European seabass (chapter 4), the interaction between foraging shore crabs and common shrimps during noise (chapter 6), the cross-sensory interference by noise in foraging crabs (chapter 7), and habituation to repeated sound exposures by blue mussels (chapter 8). Future studies are needed to be able to link changes in time budgets to changes in energy budgets, and consequently to fitness. Additionally, studies into the factors that modulate the effects of sound are needed to fully understand the impact of sound. Show less
Bos, M.M.; Vries, L. de; Rensen, P.C.N.; Dijk, K.W. van; Blauw, G.J.; Heemst, D. van; Noordam, R. 2021
Background and aims: The APOE epsilon 4 genotype has a higher risk for developing coronary artery disease (CAD), but there is preliminary evidence that antioxidative lifestyle factors interact with... Show moreBackground and aims: The APOE epsilon 4 genotype has a higher risk for developing coronary artery disease (CAD), but there is preliminary evidence that antioxidative lifestyle factors interact with APOE genotype on CAD risk. Here, we assessed the effect modification of physical activity, oily fish and polyunsaturated fatty acid (PUFA) intake with APOE genotype on risk of incident CAD. Methods: The present study comprised 345,659 white European participants from UK Biobank (mean age: 56.5 years, 45.7% men) without a history of CAD. Information regarding physical activity, oily fish intake and PUFA intake was collected through questionnaires, and information on incident CAD through linkage with hospital admission records. Analyses were performed using Cox proportional hazard models adjusted for age and sex. Results: Higher physical activity level and oily fish intake were both associated with a lower incidence of CAD. However, these associations were similar across the different APOE genotypes (p-values for interaction > 0.05). Most notable, higher PUFA intake was associated with a lower CAD risk in APOE epsilon 4 genotype carriers (hazard ratio: 0.76, 95% confidence interval: 0.63-0.92), and not in APOE epsilon 3/epsilon 3 genotype carriers (0.90; 0.79, 1.02), but without statistical evidence for effect modification (p-valueinteraction = 0.137). Conclusions: While higher physical activity and high fish and PUFA intake were associated with a lower risk of incident CAD, no evidence for interaction of these lifestyle factors with APOE genotype was observed in UK Biobank participants. Interventions intended to reduce cardiovascular risk might therefore be similarly effective across the APOE genotype carriers. Show less
The effects of anthropogenic noise on interactions between predators and their prey are still little understood. This thesis aims to fill pressing knowledge gaps on this topic by studying how... Show moreThe effects of anthropogenic noise on interactions between predators and their prey are still little understood. This thesis aims to fill pressing knowledge gaps on this topic by studying how anthropogenic noise affected various stages in the prey-hunting of predators and the predator-avoidance of prey. For predators, I investigated whether an¬thropogenic noise could influence habitat choice (chapters 2 and 3), foraging efficiency (chapter 3) and communication between foraging group members (chapter 4). For prey, I studied how anthropogenic noise affected prey behaviour outside of predation con¬texts (chapter 5) and if current and previous vessel noise exposure affected anti-predator behaviour when a simulated predator attacked (chapter 6). The multi-disciplinary studies of this thesis combine to unravel more insight into the influence of noise on predator-prey relationships in the marine environment. Further investigations should focus on revealing the mechanistic underpinning of noise effects on behaviour of both predator and prey. Only then will we be able to reduce the impact of noise on marine ecosystems. Show less
There is a fundamental difference between mammals and fish in how hypoxia affects the lipid metabolism by means of the stress hormone noradrenaline. In mammals, hypoxia induces an increase in lipid... Show moreThere is a fundamental difference between mammals and fish in how hypoxia affects the lipid metabolism by means of the stress hormone noradrenaline. In mammals, hypoxia induces an increase in lipid metabolism, which can eventually lead to tissue damage due to elevated plasma fatty acid levels, e.g. in case of a heart attack. However, hypoxia is not a normally occurring situation in healthy mammals as opposed to many fish species, because water is a relative poor source of oxygen. In hypoxic fish therefore, noradrenaline mediates a decrease in lipid metabolism, and we believe that this is a general protection mechanism in fish against lipid poisoning. There is a clear difference in the mode of breathing between mammals and fish, namely air- vs. water-breathing. Hence, we hypothesise that this difference is the cause for the opposing effects of noradrenaline. Therefore, we studied the effects of hypoxia on an air-breathing fish, the African catfish. However, physiologically this species reacted the same as other water-breathing fish, namely by means of a reduced lipid metabolism. Additionally, we demonstrated that, despite the opposing effects on the lipid metabolism, the transduction pathways in fish and mammals are very alike, and thus only a minor change has occurred in the course of evolution. This research has aided in a better understanding of the evolutionary changes in lipid metabolism.|Er is een fundamenteel verschil tussen zoogdieren en vissen in hoe het vetmetabolisme onder hypoxie (=zuurstoftekort) wordt veranderd door het stresshormoon noradrenaline. In zoogdieren leidt hypoxie tot een verhoogd vetmetabolisme, wat uiteindelijk zelfs weefselschade kan veroorzaken door te hoge vetzuurgehaltes, b.v. bij een hartaanval. Gezonde zoogdieren komen normaliter niet in zuurstofnood, in tegenstelling tot veel vissoorten, omdat water een relatief arme zuurstofbron is. In hypoxische vissen daalt dan ook het vetmetabolisme door noradrenaline, en wij denken dat dit een beschermingsmechanisme is tegen een vetzuurvergiftiging. Er is een duidelijk verschil in de manier van ademhalen van zoogdieren en vissen, respectievelijk lucht- en waterademhaling, en dit verschil ligt mogelijkerwijs ten grondslag aan deze verschillende effecten van noradrenaline; dit is de centrale hypothese van het onderzoek. Daarom is gekeken naar het effect van zuurstoftekort bij een luchtademhalende vissoort, de Afrikaanse meerval. Deze vis bleek echter fysiologisch hetzelfde te reageren als waterademhalende vissen, namelijk een verlaagd vetmetabolisme. Daarnaast is aangetoond dat, ondanks tegenovergestelde effecten op het vetmetabolisme, de aansturingmechanismen in vissen en zoogdieren vergelijkbaar zijn, en dat er dus maar een minimale verandering in de evolutie heeft plaatsgevonden. Dit onderzoek heeft bijgedragen tot een beter begrip van de evolutionaire veranderingen in het vetmetabolisme. Show less
