S Gudmundsdóttir

Characterization of a collagenolytic serine proteinase from the Atlantic cod (Gadus morhua).

A collagenolytic proteinase was purified from the intestines of Atlantic cod by (NH4)2SO4 fractionation, hydrophobic interaction chromatography (phenyl-Sepharose) and ion-exchange chromatography (DEAE-Sepharose). The proteinase has an estimated molecular weight of 24.1 (+/- 0.5) kDa as determined by SDS-PAGE and belongs to the chymotrypsin family of serine proteinases. The enzyme cleaves native collagen types I, III, IV and V, and also readily hydrolyzes succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (sAAPFpna), an amide substrate of chymotrypsin, as well as succinyl-L-Ala-L-Ala-L-Pro-L-Leu-p-nitroanilide, a reported elastase substrate, but had no detectable activity towards several other substrates of these proteinases or of trypsin. The pH optimum of the enzyme was between pH 8.0 and 9.5 and it was unstable at pH values below 7. Maximal activity of the enzyme when assayed against sAAPFpna was centered between 45 and 50 degrees C. Calcium binding stabilized the cod collagenase against thermal inactivation, but even in the presence of calcium, the enzyme was unstable at temperatures above 30 degrees C.

Plasma fatty acids and lipids in two separate, but genetically comparable, icelandic populations

Levels of serum lipids and lipoproteins, and the fatty acid composition of plasma phospholipids, were measured in two genetically comparable, but widely separated, populations. The 1975 mortality rates for ischemic heart disease were significantly higher in one of these populations, the Manitoban residents of pure Icelandic descent, than in the other, a rural population from Northeastern Iceland. Two study populations, Icelanders and Icelandic-Canadians, were drawn from these larger populations. The study populations were matched for age and sex and divided into three age groups, 20–39, 40–59, and 60–69 years. In comparison to the Icelandic-Canadians, the Icelanders exhibited significantly higher levels of total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol, but lower triglyceride levels. Their plasma phospholipids contained significantly lower levels of saturated fatty acids (SFA), monounsaturated fatty acids, and n−6 polyunsaturated fatty acids (PUFA); but their n−3 PUFA levels were three times as high. It was additionally found that fatty acid composition of plasma phospholipids differed among Icelanders of different ages. SFA levels were significantly lower, and n−6 PUFA levels significantly higher, in the 20–39 year group than in the 60–69 year group, possibly due to different dietary fat consumption patterns between generations. No corresponding age-related difference in the fatty acid composition of plasma phospholipids was found in the Icelandic-Canadian study population. As the Icelandic and Icelandic-Canadian groups are assumed to be genetically similar, the biochemical differences between them are evidently due to environmental, probably dietary, differences. The findings indicate that n−3 PUFA may be cardioprotective in the context of an otherwise atherogenic diet.

Specific and natural antibody response of cod juveniles vaccinated against Vibrio anguillarum.

The purpose of the present study was to study specific and natural antibody levels in individual cod juveniles before and after being vaccinated against Vibrio anguillarum. Different vaccine preparations and vaccination regimes, i.e. bathing, dipping, i.p. injection or combination of treatments were employed and the performance of different groups to bath challenge by the bacterium tested. Antibody responses to V. anguillarum antigens in groups vaccinated by bathing and/or dipping were negligible, while responses were observed in i.p. injected fish. Fish receiving i.p. injection in addition to bathing, showed significant antibody response. Both groups showed increased levels of natural antibodies while levels were low in other groups. Fish bathed or dipped showed higher mortality when challenged than untreated fish, while fish that received a second vaccination showed the best protection. It was not ascertained whether there is a long term difference between the effects of immersion versus i.p. injection as a booster method. Levels of antibodies against V. anguillarum antigens or natural antibodies in groups with the lowest mortalities show that neither could have been used to predict protection given by the vaccines tested.

The Carbohydrate Moiety of IgM From Atlantic Salmon (Salmo salar L.)

The carbohydrate moiety of salmon IgM was estimated to be about 12.5% of the total molecular weight of salmon IgM based on SDS-PAGE analysis and #8.0% based on FACE analysis. The carbohydrate moiety was restricted to the heavy chain and was all N-linked. Six different oligosaccharides were identified using the FACE oligosaccharide profiling technique. Monosaccharide composition analysis, as well as digestion with endoglycosidase H, suggested that the oligosaccharides were mainly of the complex type rather than high mannose type. Removal of about 80% of the carbohydrate affected the sensitivity of IgM to trypsin but had no effects on antigen binding or the complement fixation ability of anti s-RBC IgM. comp biochem physiol 116B; 4:423-430, 1997.

Yersiniosis in Atlantic cod, Gadus morhua (L.), characterization of the infective strain and host reactions

A disease outbreak in farmed Atlantic cod caused by Yersinia ruckeri is reported. Mortality started following vaccination of cod reared in two tanks (A and B). The accumulated mortality reached 1.9% in A and 4.8% in B in the following 30 days when treatment with oxytetracycline was applied. Biochemical and molecular analysis of Y. ruckeri isolates from the cod and other fish species from fresh and marine waters in Iceland revealed a high salinity-tolerant subgroup of Y. ruckeri serotype O1. Infected fish showed clinical signs comparable with those of Y. ruckeri -infected salmonids, with the exception of granuloma formations in infected cod tissues, which is a known response of cod to bacterial infections. Immunohistological examination showed Y. ruckeri antigens in the core of granulomas and the involvement of immune parameters that indicates a strong association between complement and lysozyme killing of bacteria. Experimental infection of cod with a cod isolate induced disease, and the calculated LD50 was 1.7 × 10(4) CFU per fish. The results suggest that yersiniosis can be spread between populations of freshwater and marine fish. Treatment of infected cod with antibiotic did not eliminate the infection, which can be explained by the immune response of cod producing prolonged granulomatous infection.

Levels of Renibacterium salmoninarum antigens in resident and anadromous salmonids in the River Ellidaár system in Iceland

In relation to stock enhancement programmes, wild salmon broodfish have been routinely screened for the presence of Renibacterium salmoninarum antigens (Rs-Ag) for decades. A sudden increase in the prevalence of Rs-Ag experienced caused extensive problems to this industry as eggs from positive fish are discarded. The prevalence and level of Rs-Ag were examined in resident and anadromous salmonids in the River Ellidaár system and the progress of Rs-Ag in a cohort of salmon followed. Both prevalence and Rs-Ag levels were high in resident salmonids and emigrating salmon smolts in the river system. When the smolts re-entered their home river as adults the following summer, they were almost free of Rs-Ag, but the longer they stayed in the river, the more Rs-Ag they acquired; the majority being positive at spawning. This study demonstrates a high level of Rs-Ag in salmonids in the River Ellidaár system which significantly reduces in the salmon during its seawater phase. Accordingly, it seems ideal to sample salmon broodfish as soon as possible after ascending the river and subsequently transfer to Rs-free environment for storage until stripping, which could result in lower Rs-prevalence and minimize the problems that stock enhancement programmes have faced due to Rs-positive wild broodfish.