Glycosylation analysis of two cysteine proteinase inhibitors from Atlantic salmon skin: di-O-acetylated sialic acids are the major sialic acid species on N-glycans.
(73/793)
We have recently identified two novel cysteine proteinase inhibitors from the skin of Atlantic salmon (Salmo salar L.), named salmon kininogen and salarin. In preliminary experiments, the proteins were found to be both N- as well as O-glycosylated. In the present study we show that both proteins carry biantennary alpha2,3-sialylated N-glycans. A very high amount of O-acetylated Neu5Ac units are present in the N-glycans, comprising about 60% di-O-acetylated species. Non-O-acetylated Neu5Ac make up less than 5% of the sialic acids in the N-glycans. A small number of Neu5Acalpha2-8Neu5Ac structures were observed in the N-glycans as well. O-glycans from both proteins were recovered by reductive beta-elimination and were identified by mass spectrometric methods as mono- and disialylated core type 1 tri- and tetrasaccharides. The method used for O-glycan isolation prevented the identification of possible O-acetylation in the O-glycan-bound sialic acids, but O-acetylation was observed in one O-glycosylated peptide isolated from trypsin digest of salarin. The chemical nature of the sialic acid modifications was further studied by liquid chromatography tandem mass spectrometry of 1,2-diamino-4,5-methylenedioxybenzene-derivatized sialic acids, revealing 7-, 8-, and 9- but no 4-O-acetylation. To our knowledge, these are the first observations of sialic acid O-acetylation in N-glycans on fish species and represent clearly the most extensive N-glycan O-acetylation described on any species. (+info)
The aunt and uncle effect: an empirical evaluation of the confounding influence of full sibs of parents on pedigree reconstruction.
(74/793)
This study used simulations and a known two-generation pedigree of chinook salmon (Oncorhynchus tshawytscha) to evaluate the effect of full sibs of parents on pedigree reconstruction. Parentage analysis was conducted on 100 parent pair-offspring relationships from pedigrees with unrelated (simulation) and related (chinook salmon) candidate parents. Parentage assignment success for the chinook salmon was lower than in the simulated populations. For example, the six most variable loci (mean H(E) = 0.87) provided a mean of 97% unambiguous assignments in the simulated population and 67% unambiguous assignments for the chinook salmon. Estimates of the pairwise relatedness coefficient ((xy)) for most nonexcluded false parents and true parents of chinook salmon offspring exceeded 0.50. These results support the conclusion that closely related candidate parents decrease the power of genetic markers for pedigree reconstruction based on exclusion. Ambiguous parentage may be resolved using single parent- and parent pair-offspring likelihood analysis, however, these methods should be used with caution and they are not replacements for using more loci when many candidate parents are full sibs. (+info)
Accurate partition of individuals into full-sib families from genetic data without parental information.
(75/793)
Two Markov chain Monte Carlo algorithms are proposed that allow the partitioning of individuals into full-sib groups using single-locus genetic marker data when no parental information is available. These algorithms present a method of moving through the sibship configuration space and locating the configuration that maximizes an overall score on the basis of pairwise likelihood ratios of being full-sib or unrelated or maximizes the full joint likelihood of the proposed family structure. Using these methods, up to 757 out of 759 Atlantic salmon were correctly classified into 12 full-sib families of unequal size using four microsatellite markers. Large-scale simulations were performed to assess the sensitivity of the procedures to the number of loci and number of alleles per locus, the allelic distribution type, the distribution of families, and the independent knowledge of population allelic frequencies. The number of loci and the number of alleles per locus had the most impact on accuracy. Very good accuracy can be obtained with as few as four loci when they have at least eight alleles. Accuracy decreases when using allelic frequencies estimated in small target samples with skewed family distributions with the pairwise likelihood approach. We present an iterative approach that partly corrects that problem. The full likelihood approach is less sensitive to the precision of allelic frequencies estimates but did not perform as well with the large data set or when little information was available (e.g., four loci with four alleles). (+info)
A model of salmon louse production in Norway: effects of increasing salmon production and public management measures.
(76/793)
Salmon lice Lepeophtheirus salmonis Kroyer have caused disease problems in farmed Atlantic salmon Salmo salar L. since the mid-1970s in Norway. High infection intensities and premature return of wild sea trout Salmo trutta L. were first reported in 1992. Later emaciated wild Atlantic salmon smolts carrying large amounts of lice have been observed both in fjords and offshore. The Norwegian Animal Health Authority regulations to control the problem, which came into operation in 1998, included compulsory louse level monitoring in farms and maximum legal numbers of lice per fish. Here, we present a model of salmon louse egg production in Norway and show that the effect of the current public management strategy is critically dependent on the yearly increase in salmon production. This is because the infection pressure is the product of the number of fish in the system, and the number of lice per fish. Due to the much larger number of farmed than wild salmonids, it is highly likely that lice originating from farmed salmon infect wild stock. Estimated tolerance limits for wild salmonids vary widely, and the level of louse egg production in farms which would be needed to decimate wild populations is not known. Two possible thresholds for total lice egg production are investigated: (1) 1986 to 1987 level (i.e. before adverse effects on sea trout were recorded), and (2) a level corresponding to a doubling of the estimated natural infection pressure. The farm lice per fish limits that would have to be observed to keep louse production within the 2 thresholds are calculated for the period 1986 to 2005. A steady decrease in the permitted number of lice per fish may keep the total louse production stable, but the number of salmon required for verification of lice numbers will increase as the prevalence to be verified is decreased. At threshold (2), the model estimated that lice limits should have been 0.05 louse per fish in 1999. This would require 60 fish from each pen to be collected, anaesthetised and examined for a good estimate at a confidence level of 95%. Such sample numbers are likely to be opposed by farmers. The use of national delousing programs to solve the problem is discussed. (+info)
Novel expression of the stanniocalcin gene in fish.
(77/793)
It is currently accepted that the fish stanniocalcin (STC) gene is expressed exclusively in the corpuscles of Stannius (CS), unique endocrine glands on the kidneys of bony fishes. In this study, we have re-examined the pattern of fish STC gene expression in the light of the recent evidence for widespread expression of the gene in mammals. Surprisingly, we found by Northern blotting that the fish gene was also expressed in the kidneys and gonads, in addition to the CS glands. Moreover, Southern blotting of RT-PCR products revealed STC mRNA transcripts in all tissues assayed, including brain, heart, gill, muscle and intestine. In situ hybridization studies using digoxigenin-labeled riboprobes localized STC mRNA to chondrocytes, and both mature and developing nephritic tubules. Immunocytochemical staining indicated that the STC protein was widespread in cells of the gill, kidney, brain, eye, pseudobranch and skin. We also characterized the salmon STC gene, establishing that it was comprised of five exons as opposed to four in mammals. A single transcription start site was identified by primer extension 99 bp upstream of the start codon. This is the first evidence of STC gene expression in fish tissues other than the CS glands and suggests that, as in mammals, fish STC operates via both local and endocrine pathways. (+info)
Effects of high intensity exercise training on cardiovascular function, oxygen uptake, internal oxygen transport and osmotic balance in chinook salmon (Oncorhynchus tshawytscha) during critical speed swimming.
(78/793)
To examine cardiorespiratory plasticity, cardiovascular function, oxygen consumption, oxygen delivery and osmotic balance were measured at velocities up to critical swimming speed (Ucrit) in seawater-adapted chinook salmon. We used two groups of fish. The control group had swum continuously for 4 months at a low intensity (0.5 BLs(-1)) and the other was given a high-intensity training regimen (a Ucrit swim test on alternate days) over the same period of time. Compared with available data for other salmonid species, the control group had a higher maximum oxygen consumption (MO2max; 244 micromol O2 min(-1) kg(-1)), cardiac output (Qmax; 65 ml min(-1) kg(-1)) and blood oxygen content (CaO2; 15 ml O2 dl(-1)). Exercise training caused a 50% increase in MO2max without changing either Ucrit or CaO2, even though there were small but significant increases in hematocrit, hemoglobin concentration and relative ventricular mass. During swimming, however, exercise-trained fish experienced a smaller decrease in body mass and muscle moisture, a smaller increase in plasma osmolality, and reduced venous oxygen stores compared with control fish. Consequently, exercise training apparently diminished the osmo-respiratory compromise, but improved oxygen extraction at the tissues. We conclude that the training-induced increase in MO2max provided benefits to systems other than the locomotory system, such as osmoregulation, enabling trained fish to better multitask physiological functions while swimming. Furthermore, because a good interspecific correlation exists between MO2max and arterial oxygen supply (TO2max; r2=0.99) among temperate fish species, it is likely that CaO2 and Qmax are principal loci for cardiorespiratory evolutionary adaptation but not for intraspecific cardiorepiratory plasticity as revealed by high intensity exercise training. (+info)
An unusual vitamin E constituent (alpha-tocomonoenol) provides enhanced antioxidant protection in marine organisms adapted to cold-water environments.
(79/793)
A new vitamin E constituent having an unusual methylene unsaturation at the isoprenoid-chain terminus of alpha-tocopherol (alpha-Toc) was isolated from chum salmon eggs and was found to have identical antioxidant activity as does alpha-Toc in methanol or liposomal suspension at 37 degrees C. Here we report that this marine-derived tocopherol (MDT) is broadly distributed with alpha-Toc in the tissue of marine fish, and that the MDT composition of total vitamin E is greater in the flesh of cold-water salmon (12-20%) than in that of tropical fish (< or =2.5%). Vitamin E analysis of cultured masu salmon maintained on a MDT-deplete diet showed substantially less MDT content than native masu salmon, suggesting a trophic origin of MDT. This contention is supported by the finding of MDT in marine plankton from the cold waters of Hokkaido. We found that MDT inhibited peroxidation of cholesterol-containing phosphatidylcholine liposomes to a greater extent than did alpha-Toc at 0 degrees C. Furthermore, the ratios of the rate constants for MDT and alpha-Toc to scavenge peroxyl radicals increased with decreasing rates of radical flux in liposomes and fish oil at 0 degrees C, indicating that the enhanced activity of MDT at low temperature is attributed to its greater rate of diffusion in viscous lipids. These results suggest that MDT production, or its trophic accumulation, may reduce lipid peroxidation in marine organisms functionally adapted to cold-water environments. (+info)
Evidence for a carrier state of infectious hematopoietic necrosis virus in chinook salmon Oncorhynchus tshawytscha.
(80/793)
In British Columbia, Canada, infectious hematopoietic necrosis virus (IHNV) is prevalent in wild sockeye salmon Oncorhynchus nerka and has caused disease in seawater net-pen reared Atlantic salmon Salmo salar. In this study, chinook salmon Oncorhynchus tshawytscha experimentally exposed to an isolate of IHNV found in British Columbia became carriers of the virus. When Atlantic salmon were cohabited with these virus-exposed chinook salmon, IHNV was isolated from the Atlantic salmon. Identification of chinook salmon populations that have been exposed to IHNV may be difficult, as virus isolation was successful only in fish that were concurrently infected with either Renibacterium salmoninarum or Piscirickettisia salmonis. Also, IHNV-specific antibodies were detected in only 2 of the 70 fish experimentally exposed to the virus. Two samples collected from chinook salmon exposed to IHNV while at a salt water net-pen site had a seroprevalence of 19 and 22%; however, the inconsistencies between our laboratory and field data suggest that further research is required before we can rely on serological analysis for identifying potential carrier populations. Because of the difficulty in determining the exposure status of populations of chinook salmon, especially if there is no concurrent disease, it may be prudent not to cohabit Atlantic salmon with chinook salmon on a farm if there is any possibility that the latter have been exposed to the virus. (+info)