Ole Torrissen - Academia.edu (original) (raw)

Papers by Ole Torrissen

Journal of Fish Diseases, 2013

Fish Physiology and Biochemistry, 1992

Chemico-Biological Interactions, 2003

Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injec... more Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injecting two model substances, paraquat and menadione, into juvenile rainbow trout (Oncorhynchus mykiss ). These two substances were chosen because of their well-known ability to redox-cycle and cause depletion of NADPH in several biological systems. Depletion of NADPH increases metabolism through the pentose-phosphate shunt and may thereby increase the need for thiamine diphosphate by heightened transketolase activity. A special food was produced with lower thiamine content than commercial food, usually enriched with thiamine, which could mask an effect on the thiamine level. After 9 weeks of exposure, glucose-6-phosphate dehydrogenase, transketolase, glutathione reductase and ethoxyresorufin O -deethylase were analysed in liver and kidney cellular sub-fractions as well as analysis of total thiamine concentrations in liver, kidney and muscle. The results showed that paraquat caused a large increase in hepatic glutathione reductase activity and induced hepatic glucose-6phosphate dehydrogenase activity, i.e., the rate-limiting enzyme in the oxidative part of the pentose-phosphate shunt. Despite this paraquat exposure did not affect transketolase activity : S 0 0 0 9 -2 7 9 7 ( 0 2 ) 0 0 1 2 2 -9 and total thiamine concentration. #

BMC Genetics, 2014

Background: The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects salmonid... more Background: The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects salmonids in the Pacific and Atlantic oceans. Although considered as a single species, morphological and biological differences have been reported between lice from the two oceans. Likewise, studies based on nucleotide sequencing have demonstrated that sequence differences between Atlantic and Pacific L. salmonis are highly significant, albeit smaller than the divergence observed between congeneric copepod species. Results: We demonstrated reproductive compatibility between L. salmonis from the two oceans and successfully established F2 hybrid strains using separate maternal lines from both the Pacific and Atlantic. The infection success for the F2 hybrid strains were similar to results typically observed for non hybrid lice strains in the rearing facility used. Lepeophtheirus salmonis COI and 16S sequences divergence between individuals from the Pacific and the Atlantic oceans was high compared to what may be expected within a copepod species and phylogenetic analysis showed that they consistently formed monophyletic clades representing their origin from the Pacific or Atlantic oceans.

Aquaculture Research, 1995

The user has requested enhancement of the downloaded file.

Aquaculture Nutrition, 1995

Aquaculture, 2005

Two types of krill meals produced from Atlantic krill and Antarctic krill were tested in two sepa... more Two types of krill meals produced from Atlantic krill and Antarctic krill were tested in two separate experiments, to replace fish meal at 0–50% (Experiment 1) and 0–100% (Experiment 2), respectively. The experimental diets, performed in duplicate, were provided to Atlantic salmon of 100 g in Experiment 1 and 1 kg in Experiment 2.The in vitro digestibility technique (using crude enzyme extracts from fish of both sizes and standardised by trypsin activity) predicted the dietary qualities in the growth trials. Studies of the relationships between trypsin specific activity with chymotrypsin specific activity and with protease activity ratio of trypsin to chymotrypsin (T/C ratio) in the pyloric caeca as well as between weight and the T/C ratio value did predict growth status of the fish. These protease values in the faeces could not predict fish growth status but could indicate fish digestive efficiency as the values in the pyloric caeca. Interestingly, there were significant relationships among feed conversion efficiency (not related to growth rate due to ad lib feeding), the in vitro digestibility value and the T/C ratio in the pyloric caeca (when growth differences were seen), with inverse levels of krill meal in the diets. Preliminary tests of the dietary quality by in vitro digestibility technique corresponded with growth studies, and indicated a possibility of inclusion of any krill meal in fish diets at 50–60% replacements, and larger fish were more sensitive to dietary quality than smaller ones. At 80–100% replacements, in vitro digestibility and feed conversion efficiency were reduced, and oocyte quality changed through increased trypsin-like specific activity that might affect egg quality and hatching success. Replacement by krill meal protein seemed to improve white muscle quality by increasing protein content through increasing protein retention, as RNA concentration and protein synthesis capacity (RNA/protein ratio) were reduced. Antarctic krill seemed to show better quality than Atlantic krill, as at the similar levels of replacement (50–60%) it did not show any adverse effect on growth, compared to the control diet.

The parasitic copepod Lepeophtheirus salmonis is responsible for huge economic losses in the salm... more The parasitic copepod Lepeophtheirus salmonis is responsible for huge economic losses in the salmonid aquaculture industry, and has been linked with declines of wild salmonid populations. In order to elucidate population genetic structure throughout the Atlantic Ocean, 2495 lice representing 27 samples collected from 22 locations were analysed for 14 microsatellite loci. Significant overall genetic variation was observed (14 loci: global F ST = 0.0057, p < 0.0001), although this decreased slightly when an outlier locus (LsalSTA3), detected as a candidate for positive selection, was removed (13 neutral loci: global F ST = 0.0022, p < 0.0001). A relationship between physical and genetic distance was observed (R 2 = 0.179, p = 0.0013), but only when data from LsalSTA3 was included. No overall genetic variation was observed among the 19 samples collected in Norway (Norwegian global F ST < 0.0001, p = 0.6). None of the within-country (Canada, Ireland, Shetland and Faroe Islands) pairwise F ST values were statistically significant when analysing the 13 neutral loci and following Bonferroni correction. Samples taken at 5 Norwegian farms did not exhibit significant genetic differences before and after medicated treatment. We conclude that L. salmonis displays weak but nevertheless statistically significant population genetic variation throughout the Atlantic. Analysis of temporal samples, potentially combined with larger numbers of markers giving greater genome coverage, will be required to fully elucidate the biological significance of the observed variation.

The Nordic countries are known for clean environment, efficient technology and high quality produ... more The Nordic countries are known for clean environment, efficient technology and high quality products, not least food products. The countries have a long history in fisheries and agriculture and aquaculture has been increasing in recent decades, especially the salmon production in Norway reaching a million tons annual production and the rainbow trout production in Denmark utilizing environmentally friendly recirculation technology. The Nordic aquaculture business has a huge potential to increase further, the global market demand for high quality environmentally beneficent products are increasing rapidly and the Nordic countries have the resources, know-how and image to respond to this with increased production. Access to safe, available and economical feed ingredients is becoming one of the most important challenges for strengthening the aquaculture industry and developing a more sustainable production. The major challenges for the industry are to reduce feed cost and environmental footprints without reducing product quality and value. In this project some realistic future possibilities for production of new local fish feed ingredients are put forward and a Nordic network has been established including the whole value chain from producers of fish feed raw material, through fish feed manufacturing and aquaculture to marketing of fish from Nordic aquaculture. Moreover, the main players in each country have been identified and are listed in the report.

Http Dx Doi Org 10 1080 10641262 2011 597890, Jul 1, 2011

The changes in microstructure and texture during smoking of fresh and frozen/thawed Atlantic salm... more The changes in microstructure and texture during smoking of fresh and frozen/thawed Atlantic salmon was studied in fish from three diÄerent origins; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon from northern and western Norway. The muscle fibers from the frozen and thawed fish shrank, and the extracellular space increased compared to the fresh

The eÄect of diÄerent conditions during the salting and smoking process on the microstructure and... more The eÄect of diÄerent conditions during the salting and smoking process on the microstructure and the texture of salmon fillets was studied in interaction with diÄerent raw salmon material; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon (Salmo salar) from Norway, one from Northern Norway and one from Western Norway. The ocean-ranched salmon was

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1984

Journal of Fish Diseases, 2013

Fish Physiology and Biochemistry, 1992

Chemico-Biological Interactions, 2003

Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injec... more Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injecting two model substances, paraquat and menadione, into juvenile rainbow trout (Oncorhynchus mykiss ). These two substances were chosen because of their well-known ability to redox-cycle and cause depletion of NADPH in several biological systems. Depletion of NADPH increases metabolism through the pentose-phosphate shunt and may thereby increase the need for thiamine diphosphate by heightened transketolase activity. A special food was produced with lower thiamine content than commercial food, usually enriched with thiamine, which could mask an effect on the thiamine level. After 9 weeks of exposure, glucose-6-phosphate dehydrogenase, transketolase, glutathione reductase and ethoxyresorufin O -deethylase were analysed in liver and kidney cellular sub-fractions as well as analysis of total thiamine concentrations in liver, kidney and muscle. The results showed that paraquat caused a large increase in hepatic glutathione reductase activity and induced hepatic glucose-6phosphate dehydrogenase activity, i.e., the rate-limiting enzyme in the oxidative part of the pentose-phosphate shunt. Despite this paraquat exposure did not affect transketolase activity : S 0 0 0 9 -2 7 9 7 ( 0 2 ) 0 0 1 2 2 -9 and total thiamine concentration. #

BMC Genetics, 2014

Background: The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects salmonid... more Background: The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects salmonids in the Pacific and Atlantic oceans. Although considered as a single species, morphological and biological differences have been reported between lice from the two oceans. Likewise, studies based on nucleotide sequencing have demonstrated that sequence differences between Atlantic and Pacific L. salmonis are highly significant, albeit smaller than the divergence observed between congeneric copepod species. Results: We demonstrated reproductive compatibility between L. salmonis from the two oceans and successfully established F2 hybrid strains using separate maternal lines from both the Pacific and Atlantic. The infection success for the F2 hybrid strains were similar to results typically observed for non hybrid lice strains in the rearing facility used. Lepeophtheirus salmonis COI and 16S sequences divergence between individuals from the Pacific and the Atlantic oceans was high compared to what may be expected within a copepod species and phylogenetic analysis showed that they consistently formed monophyletic clades representing their origin from the Pacific or Atlantic oceans.

Aquaculture Research, 1995

The user has requested enhancement of the downloaded file.

Aquaculture Nutrition, 1995

Aquaculture, 2005

Two types of krill meals produced from Atlantic krill and Antarctic krill were tested in two sepa... more Two types of krill meals produced from Atlantic krill and Antarctic krill were tested in two separate experiments, to replace fish meal at 0–50% (Experiment 1) and 0–100% (Experiment 2), respectively. The experimental diets, performed in duplicate, were provided to Atlantic salmon of 100 g in Experiment 1 and 1 kg in Experiment 2.The in vitro digestibility technique (using crude enzyme extracts from fish of both sizes and standardised by trypsin activity) predicted the dietary qualities in the growth trials. Studies of the relationships between trypsin specific activity with chymotrypsin specific activity and with protease activity ratio of trypsin to chymotrypsin (T/C ratio) in the pyloric caeca as well as between weight and the T/C ratio value did predict growth status of the fish. These protease values in the faeces could not predict fish growth status but could indicate fish digestive efficiency as the values in the pyloric caeca. Interestingly, there were significant relationships among feed conversion efficiency (not related to growth rate due to ad lib feeding), the in vitro digestibility value and the T/C ratio in the pyloric caeca (when growth differences were seen), with inverse levels of krill meal in the diets. Preliminary tests of the dietary quality by in vitro digestibility technique corresponded with growth studies, and indicated a possibility of inclusion of any krill meal in fish diets at 50–60% replacements, and larger fish were more sensitive to dietary quality than smaller ones. At 80–100% replacements, in vitro digestibility and feed conversion efficiency were reduced, and oocyte quality changed through increased trypsin-like specific activity that might affect egg quality and hatching success. Replacement by krill meal protein seemed to improve white muscle quality by increasing protein content through increasing protein retention, as RNA concentration and protein synthesis capacity (RNA/protein ratio) were reduced. Antarctic krill seemed to show better quality than Atlantic krill, as at the similar levels of replacement (50–60%) it did not show any adverse effect on growth, compared to the control diet.

The parasitic copepod Lepeophtheirus salmonis is responsible for huge economic losses in the salm... more The parasitic copepod Lepeophtheirus salmonis is responsible for huge economic losses in the salmonid aquaculture industry, and has been linked with declines of wild salmonid populations. In order to elucidate population genetic structure throughout the Atlantic Ocean, 2495 lice representing 27 samples collected from 22 locations were analysed for 14 microsatellite loci. Significant overall genetic variation was observed (14 loci: global F ST = 0.0057, p < 0.0001), although this decreased slightly when an outlier locus (LsalSTA3), detected as a candidate for positive selection, was removed (13 neutral loci: global F ST = 0.0022, p < 0.0001). A relationship between physical and genetic distance was observed (R 2 = 0.179, p = 0.0013), but only when data from LsalSTA3 was included. No overall genetic variation was observed among the 19 samples collected in Norway (Norwegian global F ST < 0.0001, p = 0.6). None of the within-country (Canada, Ireland, Shetland and Faroe Islands) pairwise F ST values were statistically significant when analysing the 13 neutral loci and following Bonferroni correction. Samples taken at 5 Norwegian farms did not exhibit significant genetic differences before and after medicated treatment. We conclude that L. salmonis displays weak but nevertheless statistically significant population genetic variation throughout the Atlantic. Analysis of temporal samples, potentially combined with larger numbers of markers giving greater genome coverage, will be required to fully elucidate the biological significance of the observed variation.

The Nordic countries are known for clean environment, efficient technology and high quality produ... more The Nordic countries are known for clean environment, efficient technology and high quality products, not least food products. The countries have a long history in fisheries and agriculture and aquaculture has been increasing in recent decades, especially the salmon production in Norway reaching a million tons annual production and the rainbow trout production in Denmark utilizing environmentally friendly recirculation technology. The Nordic aquaculture business has a huge potential to increase further, the global market demand for high quality environmentally beneficent products are increasing rapidly and the Nordic countries have the resources, know-how and image to respond to this with increased production. Access to safe, available and economical feed ingredients is becoming one of the most important challenges for strengthening the aquaculture industry and developing a more sustainable production. The major challenges for the industry are to reduce feed cost and environmental footprints without reducing product quality and value. In this project some realistic future possibilities for production of new local fish feed ingredients are put forward and a Nordic network has been established including the whole value chain from producers of fish feed raw material, through fish feed manufacturing and aquaculture to marketing of fish from Nordic aquaculture. Moreover, the main players in each country have been identified and are listed in the report.

Http Dx Doi Org 10 1080 10641262 2011 597890, Jul 1, 2011

The changes in microstructure and texture during smoking of fresh and frozen/thawed Atlantic salm... more The changes in microstructure and texture during smoking of fresh and frozen/thawed Atlantic salmon was studied in fish from three diÄerent origins; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon from northern and western Norway. The muscle fibers from the frozen and thawed fish shrank, and the extracellular space increased compared to the fresh

The eÄect of diÄerent conditions during the salting and smoking process on the microstructure and... more The eÄect of diÄerent conditions during the salting and smoking process on the microstructure and the texture of salmon fillets was studied in interaction with diÄerent raw salmon material; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon (Salmo salar) from Norway, one from Northern Norway and one from Western Norway. The ocean-ranched salmon was

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1984