Atlantic Salmon (Salmo salar L.) as a Marine Functional Source of Gamma-Tocopherol

Gamma tocopherol (gT) exhibits beneficial cardiovascular effects partly due to its anti-inflammatory activity. Important sources of gT are vegetable oils. However, little is known to what extent gT can be transferred into marine animal species such as Atlantic salmon by feeding. Therefore, in this study we have investigated the transfer of dietary gT into salmon. To this end, fish were fed a diet supplemented with 170 ppm gT for 16 weeks whereby alpha tocopherol levels were adjusted to 190 ppm in this and the control diet. Feeding gT-rich diets resulted in a three-fold increase in gT concentrations in the liver and fillet compared to non-gT-supplemented controls. Tissue alpha tocopherol levels were not decreased indicating no antagonistic interaction between gamma- and alpha tocopherol in salmon. The concentration of total omega 3 fatty acids slightly increased in response to dietary gT. Furthermore, dietary gT significantly decreased malondialdehyde in the fillet, determined as a biomarker of lipid peroxidation. In the liver of gT fed salmon we observed an overall down-regulation of genes involved in lipid homeostasis. Additionally, gT improved the antioxidant capacity by up-regulating Gpx4a gene expression in the pyloric caeca. We suggest that Atlantic salmon may provide a marine functional source capable of enriching gT for human consumption.

Atlantic salmon (Salmo salar) parr as a model to predict the optimum inclusion of air classified faba bean protein concentrate in feeds for seawater salmon

Peer reviewed

Biological factors affecting sea survival of Atlantic salmon Salmo salar L., in Western Arm Brook and an analysis of selection by the commercial fishery of nearby St. Barbe Bay, Newfoundland

The problems faced by scientists in charge of managing Atlantic salmon (Salmo salar) stocks are : i) how to maintain spawning runs consisting of repeat spawners and large multi-sea-winter (MSW) adults in the face of selective homewater and distant commercial fisheries and , ii) how to more accurately predict returns of adults. Using data from scales collected from maiden Atlantic salmon grilse from two locations on the Northern Peninsula of Newfoundland, St. Barbe Bay and Western Arm Brook, their length at smolting was back calculated. These data were then used to examine whether the St. Barbe commercial fishery is selective for salmon of particular smolt age and/or size. Analysis indicated that come commercial fishery selected larger, but not necessarily older adults that those escaping to Western Arm Brook over the period of this study, 1978-1987. It was determined that less than average size smolts survived better than above average size smolts. Slection for repeat spawners, large MSW salmon, and larger grilse has meant reductions in the proportions of these adults in the spawning runs on Western Arm Brook. This may impact the Western Arm Brook salmon stock by increasing the population instability. Sea survival was significantly correlated with selection by the commercial fishery. Characteristics of adults in Western Arm Brook during the period of study (1978-1987) did not help in explaining yearly variation in sea survival. The characteristics of smolts, however, when subjected to multiple regression analysis explained 57.2 percent of the yearly variation in sea survival.

Regulatory factors controlling muscle mass : competition between innate immune function and anabolic signals in regulation of atrogin-1 in Atlantic salmon

The research was supported by an industrial PhD studentship between University of Aberdeen and by BioMar Ltd., for Z. Heidari.

Regulatory factors controlling muscle mass : competition between innate immune function and anabolic signals in regulation of atrogin-1 in Atlantic salmon

The research was supported by an industrial PhD studentship between University of Aberdeen and by BioMar Ltd., for Z. Heidari.

NFAT5 genes are part of the osmotic regulatory system in Atlantic salmon (Salmo salar)

Acknowledgements This study was supported by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC, BB/H008063/1), UK to DGH and SAM. Funding also came from Research Council Norway for project number 241016 for DGH and EJ. This work was carried out as part of a PhD thesis funded by the Marine Alliance of Science and Technology Scotland (MASTS).

Regulatory factors controlling muscle mass : competition between innate immune function and anabolic signals in regulation of atrogin-1 in Atlantic salmon

The research was supported by an industrial PhD studentship between University of Aberdeen and by BioMar Ltd., for Z. Heidari.

Life history & environmental effects on telomere dynamics in Atlantic salmon

While much of the study of molecular biology inevitably focuses on the parts of the genome that contain active genes, there are also non-coding regions that nonetheless play an essential role in maintaining genome integrity. One such region are telomeres, which cap the ends of all eukaryotic chromosomes and play an important role in chromosome protection. Telomere loss occurs at each cell division as a result of the ‘end replication problem’ and a relatively short telomere length is indicative of poor biological state. Thus far, the majority of studies on the dynamics and role of telomeres have been biased towards certain taxa. Research to date has mostly focussed on humans, other mammals and birds. There has been far less research on the telomere dynamics of ectotherms. It is important that we do so, especially since ectothermic vertebrates do not seem to down-regulate telomerase expression in the same way as endotherms, suggesting that their telomere dynamics may be less predictable in the later life stages. The main objective of this thesis was therefore to investigate how life history and environmental effects may influence telomere dynamics in Atlantic salmon Salmo salar. I carried out carefully designed experiments, both in the laboratory and in the wild, using a longitudinal approach where possible, in order to address a number of specific questions that are connected to this central theme. In chapter 2, I demonstrate that there can be significant links between parental life history and offspring telomere dynamics. Maternal life history traits, in particular egg size, were most strongly related to offspring telomere length at the embryonic stages. Paternal life history traits, such as early life growth rate, had a greater association with offspring telomere dynamics in the later stages of development. In chapter 3, using a wild Atlantic salmon population, I found that most individuals experienced a reduction in telomere length during the migratory phase of their life cycle; however the relative rate of telomere loss was dependent on sex, with males experiencing a relatively greater loss. Unexpectedly, I also found that juvenile salmon that had the shortest telomeres at the time of outward migration, had the greatest probability of surviving through to the return migration. In chapter 4, again using a wild system involving experimental manipulations of juvenile Atlantic salmon in Scottish streams, I found that telomere length in juvenile fish was influenced by parental traits and by direct environmental effects. Faster-growing fish had shorter telomeres and there was a greater cost (in terms of reduced telomere length) if the growth occurred in a harsher environment. I also found a positive association between offspring telomere length and the growth history of their fathers (but not mothers), represented by the number of years that fathers had spent at sea. Chapter 5 explored the hypotheses that oxidative DNA damage, catalase (CAT) antioxidant activity and cell proliferation rate are underlying mechanisms linking incubation temperature and telomere dynamics in salmon embryos. No evidence was found for any such effects, but telomere lengths in salmon embryos were found to be significantly affected by the temperature of the water in which they were living. There is also evidence that telomere length significantly increases during embryonic development. In summary, this thesis has shown that a complex mix of environmental and parental effects appear to influence telomere dynamics in Atlantic salmon, with parental effects especially evident during early life stages. It also demonstrated that telomeres lengthen through the embryo stages of development before reducing once the fry begin feeding, indicating that the patterns of telomere loss commonly found in endotherms may differ in ectotherms. Reasons for this variation in telomere dynamics are presented in the final Discussion chapter of the thesis.

Recent advances in our knowledge of the Myxozoa

In the last few years two factors have helped to significantly advance our understanding of the Myxozoa. First, the phenomenal increase in fin fish aquaculture in the 1990s has lead to the increased importance of these parasites; in rum this has lead to intensified research efforts, which have increased knowledge of the development, diagnosis, and pathogenesis of myxozoans. The hallmark discovery in the 1980s that the life cycle of Myxobolus cerebralis requires development of an actinosporean stage in the Oligochaete. Tubifex tubifex, led to the elucidation of the life cycles of several other myxozoans. Also, the life cycle and taxonomy of the enigmatic PKX myxozoan has been resolved: it is the alternate stage of the unusual myxozoan. Tetracapsula bryosalmonae, from bryozoans. The 18S rDNA gene of many species has been sequenced, and here we add 22 new sequences to the data set. Phylogenetic analyses using all these sequences indicate that: 1) the Myxozoa are closely related to Cnidaria (also supported by morphological data), 2) marine taxa at the genus level branch separately from genera that usually infect freshwater fishes; 3) taxa cluster more by development and tissue location than by spore morphology; 4) the tetracapsulids branched off early in myxozoan evolution, perhaps reflected by their having bryozoan. rather than annelid hosts; 5) the morphology of actinosporeans offers little information for determining their myxosporean counterparts (assuming that they exist), and 6) the marine actinosporeans from Australia appear to form a clade within the platysporinid myxosporeans. Ribosomal DNA sequences have also enabled development of diagnostic tests for myxozoans. PCR and in situ hybridisation tests based on rDNA sequences have been developed for Myxobolus cerebralis. Ceratomyxa shasta. Kudoa spp,, and Tetracapsula bryosalmonae (PKX). Lectin-based and antibody tests have also been developed for certain myxozoans, such as PKX and C. shasta. We also review important diseases caused by myxozoans. which are emerging or re-emerging. Epizootics of whirling disease in wild rainbow trout (Oncorhynchus mykiss) have recently been reported throughout the Rocky Mountain states of the USA. With a dramatic increase in aquaculture of fishes using marine netpens, several marine myxozoans have been recognized or elevated in status as pathological agents. Kudoa thyrsites infections have caused severe post-harvest myoliquefaction in pen-reared Atlantic salmon (Salmo salar), and Ceratomyxa spp., Sphaerospora spp., and Myxidium leei cause disease in pen-reared sea bass (Dicentrarchus labrax) and sea bream species (family Sparidae) in Mediterranean countries.