Studies of drug resistance and R factors in bacteria from pond-cultured salmonids. I. Amago (Oncorhynchus rhodurus macrostomus) and Yamame (Oncorhynchus masou ishikawae).
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Aeromonas↗
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A genetic analysis of early development in pink (Oncorhynchus gorbuscha) and chum salmon (Oncorhynchus keta) at three different temperatures.
A factorial mating design was employed in which five males were mated to each of five females in each of two stocks for both pink and chum salmon. The resulting embryos and alevins were incubated at constant water temperatures of 4, 8, and 16 degrees C for pink salmon and 3, 8, and 15 degrees C for chum salmon. Variation among families in alevin and fry survival rates, hatching, button-up time, length, and weight was the least at 8 degrees C. Heritability of traits directly correlated with fitness, such as survival rates and button-up time, was low at all temperatures (h2 less than or equal to 0.25). Maternal effects could account for a substantial portion of the variation in alevin and fry size characters. Nonadditive genetic variance accounted for more of the variation in fry size characters than in those of alevins. Negative genetic correlations were observed between embryo survival and subsequent alevin size and between hatching time and subsequent alevin and fry size. Genotype-temperature interactions could underlie a substantial amount of phenotypic variation in the developmental characters examined for both species.
Aging↗
[Changes in the content of 11-oxycorticosteroids in the blood serum of the spawning Siberian salmon Oncorhynchus keta and humpback salmon Oncorhynchus gorbuscha].
Studies have been made on 11-oxycorticosteroid content of the blood serum in spawning salmons. During sexual maturation and spawning migration, the level of 11-oxycorticosteroids in the blood serum undergoes significant changes. The pattern of these changes is similar in both of the species investigated. During fresh-water period of migration, 11-3xycorticosteroid content in the blood serum of females of O. gorbuscha is 3 times higher as compared to that during sea-water period. In O. keta, this level increases two-fold. The increased content of 11-oxycorticosteroids remains constant up to spawning. After the latter, the level of 11-oxycorticosteroids decreases reaching the values typical for sea-water period.
Adrenal Cortex Hormones↗
[Demonstration of specific gonadotropin binding sites of chum salmon (Oncorhynchus keta) in membrane preparations of granulosa cells from the ovary of amago salmon (Oncorhynchus rhodurus)].
During late vitellogenesis, radioactive iodine labelled Salmon gonadotropin binds to theca--or granulosa--membrane preparations from amago Salmon ovary. In granulosa, native hormone inhibits iodinated GTH binding, thus indicating a specific binding (70% of total binding). In theca, a lower specific binding is found while non specific binding is higher: contamination by granulosa cells, on one hand, the possible heterogeneity of theca, on the other, could account for these results.
Animals↗
Detection of infection and susceptibility of different Pacific salmon stocks (Oncorhynchus spp.) to the haemoflagellate Cryptobia salmositica.
The haematocrit centrifugation technique, modified by keeping the haematocrit tubes cold (between 1 and 10 C), was sensitive for detecting light infections of Cryptobia salmositica (as few as 75 flagellates per ml of blood). In wet mount preparations, infections lighter than 7.5 X 10(3) flagellates per ml of blood could not be detected consistently. Different Pacific salmon stocks from British Columbia demonstrated differences in susceptibility to C. salmositica in experimental studies using laboratory reared juvenile fish. Oncorhynchus keta and Oncorhynchus tshawytscha from the Big Qualicum River stocks (Vancouver Island), and Oncorhynchus nerka from the Fulton River stock (Skeena River system), were all equally susceptible and suffered high mortalities at low exposures (100 flagellates in 0.1 ml physiological saline inoculated intraperitoneally per fish). Oncorhynchus nerka from the Weaver Creek stock (Fraser River system) was the most resistant with no mortalities even at exposures of 10(6) flagellates (in 0.1 ml physiological saline) per fish. Oncorhynchus kisutch seemed to be slightly less resistant than the Weaver Creek O. nerka, but fewer than 16% of the inoculated fish died. Oncorhynchus kisutch from the Big Qualicum River seemed to be slightly more resistant than O. kisutch from the Capilano River stock (a coastal river near Vancouver), with fewer mortalities and lighter infections when the experiments were terminated. Differences in susceptibility are believed to be associated with innate, genetically transmitted resistance.
Animals↗
Phylogenetic analysis of Pacific salmon (genus Oncorhynchus) based on mitochondrial DNA sequence data.
Previous phylogenetic analyses of the fishes belonging to the genus Oncorhynchus based on mitochondrial DNA data have produced conflicting trees. This is especially true with respect to the relationships among the three most derived Pacific salmon species, the pink salmon (Oncorhynchus gorbuscha), sockeye salmon (Oncorhynchus nerka), and chum salmon (Oncorhynchus keta). Smith (Syst. Biol. 41(1): 41-57, 1992) suggested that introgression in opposite directions on either side of the Pacific ocean may account for some of the conflicting data. The ATPase 6 and ND3 mitochondrial genes were sequenced from Asian and North American representatives of several species of Pacific salmon and the aligned sequences were analyzed along with other data on these genes. Analysis of the ATPase 6 and ND3 sequence data and RFLP data gives strong support for a sister relationship between pink salmon and chum salmon.
Adenosine Triphosphatases↗
Mitochondrial DNA sequence analysis of the masu salmon--phylogeny in the genus Oncorhynchus.
We determined 2162-bp sequences from the mitochondrial genome of the masu salmon Oncorhynchus masou masou, chum salmon Oncorhynchus keta, and Atlantic salmon Salmo salar by using polymerase chain reactions. These DNA sequences span from the 3' region of the gene for ATPase subunit 6 to the 5' region of the gene for NADH dehydrogenase subunit 4L. With the aid of the sequence data from other Pacific salmonid species (Thomas and Beckenbach, 1989, J. Mol. Evol. 29: 233-245), the evolutionary distances among the masu salmon and other species in the genus Oncorhynchus were calculated. These evolutionary distances were then used to construct a neighbor-joining tree. Further, a maximum parsimony tree was constructed. The evolutionary trees that were obtained suggest that masu salmon first diverged from the common ancestor of the genus Oncorhynchus.
Animals↗
Sperm metabolism of the telost fishes Chalcalburnus chalcoides and Oncorhynchus mykiss and its relation to motility and viability.
In the teleost fish Chalcalburnus chalcoides (Cyprinidae) the influence of metabolic inhibitors, substrates, coenzymes, and oxygen concentrations on spermatozoal parameters during motility and during immotile incubation was studied, the respiration rate was characterized, representative metabolite levels were measured, and the results were compared with Oncorhynchus mykiss (Salmonidae). In Chalcalburnus chalcoides the sperm motility rate, the average path swimming velocity, the motility duration, and the viability of immotile semen were significantly reduced in the presence of inhibitors of respiration (potassium cyanide, 2.4-dinitrophenol, atractyloside). Anaerobic conditions (<1 mg O(2)/liter) and inhibition of the tricarboxylic acid cycle by malonate and >7.5 mmol/liter succinate had similar effects on the sperm motility parameters and on the viability of immotile spermatozoa. Pyruvate and coenzyme A (an acyl-group carrier during oxidative carboxylation of pyruvate) prolonged the duration of sperm motility and the viability of immotile incubated spermatozoa, and also increased the spermatozoal respiration rate. Glucose levels significantly decreased during motility and during immotile storage and, under anaerobic conditions, the levels of lactate increased indicating that pyruvate derived from glycolysis. The respiration rate and the glycolytic rate significantly increased during motility. Therefore oxidative phosphorylation, tricarboxylic acid cycle, and aerobic glycolysis are central energy-supplying pathways for spermatozoa of Chalcalburnus chalcoides. The stimulatory effect of pyruvate and coenzyme A indicated that glycolysis is a rate-controlling pathway. Similar results were obtained for Oncorhynchus mykiss with the only exception that the stimulatory effect of coenzyme A was more significant than the stimulatory effect of pyruvate. When the sperm motility-activating saline solutions were optimized in aspects of energy supply, ionic composition, and osmolality, about 50% of the motile spermatozoa swam progressively (>20 mm/sec) for about 3 min in Chalcalburnus chalcoides and in Oncorhynchus mykiss. About 20% swam progressively for >2 hr in Chalcalburnus chalcoides and for >30 min in Oncorhynchus mykiss. J. Exp. Zool. 284:454-465, 1999.
2,4-Dinitrophenol↗
Phylogeny of salmonine fishes based on growth hormone introns: Atlantic (Salmo) and Pacific (Oncorhynchus) salmon are not sister taxa.
Though salmonid fishes are a well-studied group, phylogenetic questions remain, especially with respect to genus-level relationships. These questions were addressed with duplicate growth hormone (GH) introns. Intron sequences from each duplicate gene yielded phylogenetic trees that were not significantly different from each other in topology. Statistical tests supported validity of the controversial monotypic genus Parahucho, monophyly of Oncorhynchus, and inclusion of Acantholingua ohridana within Salmo. Suprisingly, GH1 intron C (GH1C) did not support the widely accepted hypothesis that Oncorhynchus (Pacific salmon and trout) and Salmo (Atlantic salmon and trout) are sibling genera; GH2C was ambiguous at this node. Previously published data were also examined for support of Salmo and Oncorhynchus as sister taxa and only morphology showed significant support. If not sister taxa, the independent evolution of anadromy-the migration to sea and return to freshwater for spawning-is most parsimonious. While there was incongruence with and among published data sets, the GH1C intron phylogeny was the best hypothesis, based on currently available molecular data.
Animals↗
Review of the sequential development of Loma salmonae (Microsporidia) based on experimental infections of rainbow trout (Oncorhynchus mykiss) and Chinook salmon (O. tshawytscha).
Loma salmonae is a common gill parasite of salmonids, and essentially all species in the genus Oncorhynchus are susceptible. Infections occur in both fresh and salt water. Loma salmonae is directly transmissible by ingestion of spores or infected tissue. The parasite infects the wall of blood vessels of various organs, but the gill is the primary site of infection. Initial infection occurs in the intestine, and xenomas are easily detected in the gills by standard histology at 4-6 wk post-exposure. A few presporogonic stages of the parasite are found in the heart endothelium prior to xenoma formation in the gills. Ultrastructure studies of early infections demonstrated that wandering blood cells transport the meronts to the gills, and that merogony occurs in pillar cells and other cells underlying the gill endothelium. Xenomas develop in these cells, resulting in hypertrophied host cells filled with spores. Xenomas ultimately rupture, and are associated with severe inflammation in which free spores are found in macrophages. The parasites are most pathogenic during this phase of the infection, resulting in severe vasculitis and clinical disease. Both rainbow trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus ishawytscha) recover from infections, but free spores persist in kidney and spleen phagocytes for many months after xenomas are absent in Chinook salmon. Fish that have recovered from the infection show strong immunity against the parasite, lasting up to 1 year. Fish are susceptible to infection by other routes of exposure by spores; co-habitation, anal gavage, and intramuscular, intraperitoneal and intravascular injection. Autoinfection probably occurs following release of spores in blood vessels after xenomas rupture. The optimal temperature for L. salmonae infections is 15-17 degrees C, with a permissive range of 11-20 degrees C.
Animals↗
Genetic relationship among three subspecies of Oncorhynchus masou determined by mitochondrial DNA sequence analysis.
It is generally accepted that there are 3 subspecies of Oncorhynchus masou in Japan, namely, Masu salmon (Oncorhynchus masou masou (Brevoort)), Amago salmon (O. masou ishikawae Jordan & McGregor), and Biwa salmon (O. masou rhodurus Jordan & McGregor or O. masou subsp. Kimura). Since the genetic relationship of these three taxa is not well known, there has been considerable confusion over their nomenclature. We have clarified the genetic relationship among these three taxa by partially sequencing their mitochondrial DNA. Sequences of 948 base pairs from the 3' region of the ATPase subunit 6 gene to the 5' region of the cytochrome oxidase subunit 3 gene were obtained for 20 individuals including wild Biwa salmon, wild and farmed Amago and Masu salmon. Furthermore, 2,162 base pairs from the 3' region of ATPase subunit 6 gene to the 5' region of NADH dehydrogenase subunit 4L gene were determined in 4 individuals. In total, there were 26 sites of base substitutions. The haplotypes of Masu salmon and Amago salmon were similar. On the other hand, 17 of the 26 sites had substitutions characteristic of Biwa salmon. A matrix of genetic distances and maximum parsimony analysis among the haplotypes indicated that Biwa salmon is genetically more distant from Masu and Amago salmon, than Masu salmon is from Amago salmon. This means that Biwa salmon diverged from the common ancestor of the Oncorhynchus masou complex before the divergence between Masu salmon and Amago salmon.
Animals↗
Antiviral activity of various 1-beta-D-arabinofuranosyl-E-5-halogenovinyluracils and E-5-bromovinyl-2'-deoxyuridine against salmon herpes virus, Oncorhynchus masou virus (OMV).
1-beta-D-Arabinofuranosyl-E-5-bromovinyluracil (BVaraU), 1-beta-D-arabinofuranosyl-E-5-iodovinyluracil (IVaraU), 1-beta-D-arabinofuranosyl-E-5-chlorovinyluracil (CVaraU) and 1-beta-D-arabinofuranosyl-5-vinyluracil (VaraU) were examined for antiviral activity against salmon herpesvirus, Oncorhynchus masou virus (OMV) in vitro using Yamame (Oncorhynchus masou) kidney cells (YNK). BVaraU, IVaraU, CVaraU and VaraU were highly active against OMV; 50% inhibitory concentration (IC50): 0.01, 0.003, 0.003, 0.003 microgram/ml, respectively. The IC50 of 5-bromovinyl-2'-deoxyuridine (BVDU) was 0.3 microgram/ml. The lower activity may be due to cleavage of it N-glycosyl linkage by pyrimidine nucleoside phosphorylases (i.e. thymidine phosphorylase) during the incubation period. The arabinofuranosyl counterparts are resistant to this (these) enzyme(s). Both OMV-induced DNA polymerase and cellular DNA polymerase alpha were strongly inhibited by BVaraU 5'-triphosphate (BVaraUTP). In an in vivo study, daily immersion of OMV-infected chum salmon (Oncorhynchus keta) fry into aqueous solution of BVaraU (5 micrograms/ml, 30 min/day, 30 times) did not increase the life span of infected fish.
Animals↗
Chromosome painting supports lack of homology among sex chromosomes in Oncorhynchus, Salmo, and Salvelinus (Salmonidae).
The sex chromosome pair has been identified previously as the largest submetacentric pair in the genome in several species of the genus Salvelinus (eastern trouts and chars) including S. namaycush (lake trout) and as a large subtelocentric/acrocentric pair in several species of the genus Oncorhynchus (Pacific trouts and salmon). Sex chromosomes have not been identified in Salmo (Atlantic salmon and brown trout). Two paint probes, one specific for the short arm (Yp) and the other for the long arm (Yq) of the sex chromosome pair in Salvelinus namaycush were hybridized to chromosomes of Oncorhynchus mykiss (rainbow trout) and O. tshawytscha (chinook salmon) and Salmo salar (Atlantic salmon) and S. trutta (brown trout). The two probes hybridized to two different autosomal pairs in each of the Oncorhynchus species, supporting lack of homology between the sex chromosomes in the two genera. The Yp probe hybridized to interstitial regions on two different chromosome pairs in S. salar and one pair in S. trutta. The Yq probe hybridized to a different pair in both species.
Animals↗
Molecular cloning and expression of an otolith matrix protein cDNA from the rainbow trout, Oncorhynchus mykiss.
The fish otolith is a hard tissue consisting of calcium carbonate and organic matrices. The matrix proteins play important roles in otolith formation, but little is known about the nature of these proteins. In this study, matrix proteins were extracted from the otoliths of rainbow trout, Oncorhynchus mykiss, and chum salmon, Oncorhynchus keta. EDTA-soluble matrix proteins were separated by SDS-PAGE, revealing two major components in the otoliths of both species with apparent molecular masses of 55 and 43 kDa. N-terminal and some internal amino acid sequences of the 55-kDa otolith matrix protein were determined. A cDNA fragment encoding this protein of O. mykiss was amplified by reverse transcription PCR using two degenerate primers designed from the amino acid sequences. A cDNA encoding this protein was obtained by screening a saccular cDNA library using the amplified cDNA fragment as a probe. Nucleotide sequence analysis revealed that the cDNA clone has a sequence of 2.5 kb and the open reading frame encoding 344 amino acid residues. Northern blot analysis showed that mRNA of this protein is expressed specifically in the sacculus, and consistently during the day.
Amino Acid Sequence↗
Production of recombinant insulin-like growth factor-II in the development of a radioimmunoassay in rainbow trout (Oncorhynchus mykiss).
Rainbow trout (Oncorhynchus mykiss) insulin-like growth factor-II (IGF-II) cDNA was amplified by reverse transcription-polymerase chain reaction and cloned into an expression vector (parHS3) for production by Escherichia coli. Recombinant rainbow trout IGF-II (rtIGF-II) was recovered from bacterial inclusion bodies, solubilized, and purified by gel filtration chromatography under reducing conditions. After refolding of the peptide by dialysis at basic pH, we obtained a final yield of 820 micrograms/liter culture medium. The rtIGF-II appeared as a single band estimated at 80% and with molecular mass of 7.5 kDa. A homologous radioimmunoassay (RIA) for the measurement of IGF-II in trout plasma has been developed using rtIGF-II as antigen, radiolabeled tracer, and standard. RIA sensitivity was 0.1 ng/ml and the ED50 was 0.75 +/- 0.06 ng/ml. Intra- and interassay coefficients of variation were 4.04% (n = 6) and 4.56% (n = 9), respectively, at ED50 levels. Cross-reactivities of 1 and 0.1% were found for recombinant coho salmon (Oncorhynchus kisutch) IGF-I and coho salmon insulin, respectively. No cross-reactivities were found for recombinant human IGF-I and IGF-II, porcine insulin, or a variety of salmonid pituitary hormones. The interference of IGF binding proteins (IGFBP) in the RIA has been tested with and without extraction (acid/ethanol extraction or C-25 acid chromatography) of fed and fasted trout plasma samples. Parallel displacement curves were obtained for unextracted and C-25-extracted plasma but not for acid/ethanol-extracted plasma. Comparison of IGF-II levels from these samples showed a possible interference of IGFBP in the RIA in fed (19.6 +/- 1.56 ng/ml unextracted and 25.25 +/- 1.21 ng/ml extracted) and fasted (21.58 +/- 1.02 ng/ml unextracted and 9.86 +/- 1.68 ng/ml extracted) trout plasma. Finally, the displacement curves for unextracted plasma from rainbow trout, Couch's sea bream (Pagrus pagrus), and carp (Cyprinus carpio) were parallel to that of the rtIGF-II standard and not strictly parallel for tilapia (Oreochromis niloticus) and catfish (Silurus glanis) plasma. No significant cross-reaction occurred with eel (Anguilla anguilla) plasma. The rainbow trout IGF-II RIA reported in this study has low variability and is highly sensitive. Therefore it is a reliable method for measuring IGF-II levels in salmonids and some nonsalmonid fish species.
Amino Acid Sequence↗
Impacts of carbamate pesticides on olfactory neurophysiology and cholinesterase activity in coho salmon (Oncorhynchus kisutch).
Many freshwater aquatic environments in the Pacific Northwest of North America contain neurotoxic pesticides, an issue of concern given the use of many of these habitats by Pacific salmon (Oncorhynchus sp.). Pesticides such as carbamates are known to affect fundamental physiological systems (such as the enzyme acetylcholinesterase (AChE)), and have been shown to affect salmonid olfactory-mediated behaviors. A neurophysiological measure of olfactory function, the electro-olfactogram (EOG), was used in this study to examine the impacts of acute localized exposure to three carbamates (the insecticide carbofuran, the antisapstain IPBC, and the fungicide mancozeb) on olfactory function in the coho salmon (Oncorhynchus kisutch). We also examine the potential for these pesticides to alter AChE levels in the primary olfactory system and brain with brief exposures (30 min to only the olfactory rosette (OR)). In results, we find that the EOG in coho salmon is highly sensitive to brief localized exposures of two of these three carbamate pesticides. The effective nominal concentration required to cause a 50% reduction in EOG amplitude (EC50) for carbofuran was 10.4 microg/l and for IPBC was 1.28 microg/l. For mancozeb, the EC50 was higher at 2.05 mg/l. All three carbamates also affected AChE activity levels in the OR and brain (BR): carbofuran exposure at 200 microg/l significantly inhibited AChE activity in the OR, and both IPBC and mancozeb significantly increased AChE activity in BR at multiple concentrations with acute localized exposure. These carbamate effects highlight the sensitivity of salmon olfactory neurophysiology to pesticides acting not only potentially via AChE-inhibition, but also by other currently unknown modes of action.
Analysis of Variance↗
Do sperm contribute to the buffering capacity of steelhead trout (Oncorhynchus mykiss) semen?
The motility of salmonid sperm is pH-sensitive and the buffering capacity of the seminal plasma is low. The objective of the present study was to determine the extent to which sperm contribute to the buffering capacity of whole steelhead (Oncorhynchus mykiss) semen. To determine the buffering capacity, semen and seminal plasma samples were titrated with HCl and pH measurements taken at 1-2 min. The buffering capacity of semen was not different from that of seminal plasma over the pH range 7.5 to 8.5 and was approximately 15% to 20% less over the range 6.0 to 7.0. Comparable results were obtained for the semen and seminal plasma of the chinook salmon (Oncorhynchus tshawytscha). To assess whether the intracellular environment could influence the buffering capacity, the effects of cell disruption with n-butanol and Triton X-100 (TX-100) were determined. Over the pH range 7.5 to 8.5, the presence of n-butanol or TX-100 resulted in a doubling of the buffering capacity of the semen; TX-100, but not n-butanol, increased semen buffering capacity over the pH range 6.0 to 7.0. To determine whether the sperm's intracellular compartment might contribute to the buffering capacity over a longer duration, semen and seminal plasma samples were acidified with HCl and the pH measured over several hours. These data suggest that intact sperm contribute no more than about 25% to the buffering capacity of whole semen. The buffering capacity of steelhead semen and seminal plasma were comparably and modestly temperature sensitive. The results suggest that the sperm may contribute to the buffering capacity of the semen over a physiological pH range, however, if so, the effect is relatively small.
Animals↗
Rainbow trout (Oncorhynchus mykiss) cystatin C: expression in Escherichia coli and properties of the recombinant protease inhibitor.
Cystatins are a superfamily of low Ki cysteine proteinase inhibitors found in both plants and animals. Cystatin C, a secreted molecule of this family, is of interest from biochemical and evolutionary points of view, and also has biotechnological applications. Recently we cloned and sequenced the cDNA for rainbow trout (Oncorhynchus mykiss) cystatin C [Li et al., 1998. Molecular cloning, sequence analysis and expression distribution of rainbow trout (Oncorhynchus mykiss) cystatin C. Comp. Biochem. Phys. B 121, 135-143]. To explore the relationship between protein structure and function of trout cystatin C, we established a bacterial system for expression of the protein. Trout cystatin C expressed in the cytoplasm of bacterial cells did not have detectable protease inhibitory activity. Activity was regained by Ni-NTA chromatography under denaturing conditions followed by dialysis-based refolding. Titration of purified cystatin C preparations with papain indicated that approximately 20% of the total protein had been converted to the active form after one refolding cycle. Expression levels were 3-5 mg/l. The protease-inhibitory properties of recombinant trout cystatin C were similar to those of human and chicken cystatin C derived from biological sources and recombinant cystatin C derived from rat and mouse genes. The Ki for papain was 1.2 x 10(-15) M, exhibiting the high affinity binding unique to this family of protease inhibitors.
Animals↗