Age‐related thermal habitat use by Pacific salmon Oncorhynchus spp.

Age‐related thermal habitat use by sockeye Oncorhynchus nerka, chum Oncorhynchus keta and pink Oncorhynchus gorbuscha salmon was examined using trawl data obtained in spring in the North Pacific Ocean. Thermal habitat use differed by species and age. Larger and older fishes inhabited cooler areas, whereas smaller and younger fishes inhabited warmer areas.     

Olfactory perception in migrating salmon. I. L-serine,a salmon repellent in mammalian skin

The properties of a repellent for migrating salmon present in mammalian skin are discussed. l-Serine which is present in the washings of human skin has been shown to have repellent activity at extremely high dilution.     

Enolase isozymes in Coho salmon.

1. Analysis of the enolase isozymic distribution has been performed in tissues of the Coho salmon, using electrophoretic separation on cellulose acetate strips followed by localization of enzymatic activity. 2. A total of six electrophoretically distinct forms are seen in Coho salmon in patterns that differ both qualitatively and quantitatively from one tissue to another. 3. The isozymes in skeletal muscle and liver are sufficiently similar to one another that a purification procedure previously developed for trout muscle enolase by Cory & Wold (1966) can be used to partially purify enolase from either of the above-mentioned Coho tissues. The main form of enolase in Coho muscle has an isoelectric point of 7.57. 4. Both liver and skeletal muscle enolases can be reversibly denatured in guanidine HCl and subsequently renatured. Liver enolase appeared to renature somewhat faster than muscle enolase under the same conditions. 5. While polyploidy among salmonids may contribute to the complexity of enolase patterns in fish, the differences in isozymic patterns seen from one tissue to another indicate the presence of distinct, nonallelic genes, probably arising through gene duplication.     

DNA nicking--closing activity from salmon testis.

Salmon testis is a good source of DNA nicking--closing (N--C) enzyme, as expected for rapidly proliferating cells. Partial purification was obtained but it resulted in an unstable form of N--C enzyme. Cruder fractions are useful for relaxing supercoiled DNA under conditions where other N--C enzymes are inactive. The enzyme is very tolerant of salt concentration, with activity still detectable at 0.6 M NaCl. It is also active at low temperatures with reasonable activity at 0 degrees C. However, at temperatures greater than 25 degrees C it is rapidly inactivated. Otherwise, its properties are similar to other eucaryotic N--C enzymes.     

Recombinant genotypes in backcrosses of male Atlantic salmon × brown trout hybrids to female Atlantic salmon

When male hybrids of Atlantic salmon × brown trout were backcrossed to female Atlantic salmon, approximately 1% of diploid progeny hatched. These were shown to exhibit recombinant genotypes when examined electrophoreticalty at five enzyme loci. This is the first confirmation of genie recombination in backcrosses of these species. Triploidization greatly increases the proportion of backcross progeny which hatch.     

Phosphatydylglycerol promotes bilayer insertion of salmon calcitonin.

Neutron diffraction from oriented multibilayers has been used to study the bilayer interaction of the amphipathic peptide salmon calcitonin. Penetration of calcitonin into bilayers composed of dioleoylphosphatidylcholine increases with the addition of 15% (mol) of the anionic phospholipid dioleoylphosphatidylglycerol. Neutron scattering profiles of water distribution in stacked bilayers show a continuous band of deuterons across each bilayer, consistent with the suggestion that the hormone forms transbilayer alpha-helixes under these conditions. These experiments add to the growing body of data on the role of phosphatidylglycerol in bilayer insertion of protein helices and suggests a possible evolutionary history for calcitonin.     

A convergent liquid-phase synthesis of salmon calcitonin.

Salmon calcitonin (sCT) was prepared in good yield and high purity by the condensation of Nalpha-Boc-cyclic decapeptide, Boc-C1SNLSTC7VLG-OH (1,7-disulfide), with protected docosapeptide (Psc)LSQE(OPse)LHK(Psc)LQTYPRTNTGSGTP-NH2 x 3TFA, followed by deprotection of Boc with trifluoroacetic acid and Psc/Pse with piperidine. The 2-(phenylsulfonyl)ethoxycarbonyl (Psc) and 2-(phenylsulfonyl)ethyl (Pse) protecting groups were recently developed. The two peptides were built up by stepwise and fragment condensation using appropriate Nalpha-Boc-amino acids and subsequent deprotection in solution. The synthetic sCT exhibited hypocalcemic potency of more than 4000 IU/mg in rats.     

Antifreeze protein gene transfer in Atlantic salmon.

Salmonids freeze to death if they come into contact with ice. Many marine fish species that inhabit icy sea waters synthesize antifreeze proteins (AFP) to protect them from freezing. Production of stable lines of freeze-resistant salmon and other species would greatly facilitate development of sea-pen aquaculture in many regions. We successfully introduced winter flounder AFP genes into Atlantic salmon. Research to date indicates stable genomic integration and low levels of expression of winter flounder AFP genes in a small number (approximately 3%) of salmon developed from microinjected eggs. Inheritance of the AFP gene by offspring (F1) from crosses between transgenic and wild-type salmon revealed that the transgenic flounders (F0) were germ-line mosaics. Low levels of AFP precursors could be detected in the blood of all these transgenic offspring (F1). Approximately 50% of the progeny produced by crosses between transgenic F1 and wild-types contained the AFP genes. These results demonstrate that stable germ-line transformed Atlantic salmon can be produced.     

Ice‐dependent winter survival of juvenile Atlantic salmon

Changes in snow and ice conditions are some of the most distinctive impacts of global warming in cold temperate and Arctic regions, altering the environment during a critical period for survival for most animals. Laboratories studies have suggested that reduced ice cover may reduce the survival of stream dwelling fishes in Northern environments. This, however, has not been empirically investigated in natural populations in large rivers. Here, we examine how the winter survival of juvenile Atlantic salmon in a large natural river, the River Alta (Norway, 70°N), is affected by the presence or absence of surface ice. Apparent survival rates for size classes corresponding to parr and presmolts were estimated using capture‐mark‐recapture and Cormack‐Jolly‐Seber models for an ice‐covered and an ice‐free site. Apparent survival (Φ) in the ice‐covered site was greater than in the ice‐free site, but did not depend on size class (0.64 for both parr and presmolt). In contrast, apparent survival in the ice‐free site was lower for larger individuals (0.33) than smaller individuals (0.45). The over‐winter decline in storage energy was greater for the ice‐free site than the ice‐covered site, suggesting that environmental conditions in the ice‐free site caused a strong depletion in energy reserves likely affecting survival. Our findings highlight the importance of surface ice for the winter survival of juvenile fish, thus, underpinning that climate change, by reducing ice cover, may have a negative effect on the survival of fish adapted to ice‐covered habitats during winter.     

Vascular effects of acetylcholine, catecholamines and detergents on isolated perfused gills of pink salmon, Oncorhynchus gorbuscha coho salmon, O. kisutch and chum salmon, O. keta

Acetylcholine caused vasoconstriction whilst adrenaline and isoprenaline caused vasodilation in isolated perfused Pacific salmon gills. The detergent LAS produced concentration dependent vasodilation when present in the perfusate in concentrations of 0.6 to 3 mg 1⁻¹. The effect of LAS was partly blocked by propranalol suggesting the involvement of β-adrenergic receptors. The maximum responses obtained with acetylcholine, adrenaline or LAS were all much greater in sea water or pre-spawning freshwater fish than in spawning fish.     

Fish pituitary gonadotropins. Characteristics of salmon gonadotropic hormones

This review presents an attempt to systematize the fish gonadotropin investigations data, particularly concerning salmons. The common characterization of pituitary glycoprotein hormones of Vertebrata is presented. A brief review of the history of investigating fish gonadotropins is given. Immunological properties, subunit composition, carbohydrate component and gonadotropin receptors are described. The sequence data comparison and analysis are presented.     

Immune response of U.D.N.-infected salmon to Saprslegnia

Sera from salmon Sulnio salar L. suspected of U.D.N.-infection were tested (by double gel diffusion) against antigens prepared from diseased salmon tissues and Suprolegniu . Precipitating antibodies to the fungus were found in 93 % of the salmon, but only 66% of these fish were colonized by fungus. The antibodies were detected in parr and adult salmon.     

Cysteine protease inhibitor in egg of chum salmon.

Two different cysteine protease inhibitors (Forms I and II) were isolated from chum salmon egg, and their molecular weights were found to be 16,000 and 11,000, respectively. When the N-terminal amino acid sequences of Forms I and II were compared, 67% of the residues were identical but no apparent homology was found between these inhibitors and cystatins of higher vertebrates. Because the amounts of half-cystine were estimated to be 7-8 residues per molecule, they can be classified into a new group of the cystatin superfamily.     

Diphyllobothrium latum infection after eating domestic salmon flesh.

Diphyllobothrium latum infection in human is not common in Korea and only thirty seven cases have been reported since 1921. We report two cases of fish tapeworm infection after ingestion of raw cherry salmon (Oncorhynchus masou) caught in the domestic river. Among four family members who ate together raw salmon flesh six months ago, just two, mother and daughter, were infected. It is our expectation that the salmon associated tapeworm infections would be enlisted as one of the major parasitic problems with the growing consumption of salmon in Korea.     

Short‐term freshwater exposure benefits sea lice‐infected Atlantic salmon

Atlantic salmon Salmo salar were infected with sea lice Lepeophtheirus salmonis (0·08 ± 0·007 sea lice g⁻¹) over a period of 4 h. Both infected and non‐infected fish were swim tested in sea water (SW) and fresh water (FW). The ventral aorta of each fish was fitted with a Doppler cuff in order to measure cardiac output, stroke volume and heart rate during swim testing. Blood samples were taken at rest and after exercise. Critical swimming speed of infected fish in SW (2·14 ± 0·08 body lengths, bl s⁻¹) was significantly lower ( P  < 0·05) than infected fish switched to FW (2·81 ± 0·08 bl s⁻¹) and non‐infected fish in SW (2·42 ± 0·04 bl s⁻¹) and FW (2·61 ± 0·08 bl s⁻¹). Cardiac and blood results indicated infected fish exposed to FW did experience stress, but relief from osmotic and ionic distress probably reduces energy expenditure, allowing the increase in performance. As the performance of sea lice‐infected fish improved upon transfer to FW, it is likely that heavily infected salmonids do return to FW to restore compromised osmotic and ionic balance, and remove sea lice in the process.     

Clonal Atlantic salmon × brown trout hybrids produced by gynogenesis

Clonal full-sib progeny groups of Atlantic salmon Salmo salar × brown trout Salmo trutta hybrids were produced by gynogenesis. Eggs obtained from two 3-year-old Atlantic salmon (female) × brown trout (male) F₁ hybrids were activated with UV-irradiated rainbow trout Oncorhynchus mykiss sperm. Fecundity, percentage egg activation and percentage survival to completion of yolk-sac absorption were similar for the two females, and averaged 800 eggs kg⁻¹, 90 and 65%, respectively. Flow cytometric and protein electrophoretic analyses confirmed the progeny to be diploid hybrids. Isogenicity within progeny groups and to the maternal parent was indicated by identical DNA fingerprint patterns detected with multilocus oligonucleotide probes–GATA₍₅₎ and ACTG_(n). Isogenicity was also observed in the gynogenetic progeny of a third female spawned the following year. It appeared that a large portion of the oocytes in females of this hybrid underwent a premeiotic chromosome doubling, or possibly a complete suppression of meiosis. The result was ovulation of diploid eggs, each possessing a full set of both Atlantic salmon and brown trout chromosomes identical to those in the maternal somatic cells. Lines of clonal hybrids could therefore be perpetuated by gynogenesis and would have potential both as experimental animals and in commercial aquaculture.     

Long‐distance downstream movements by homing adult chinook salmon

Unusually long downstream movements totalling several hundred kilometres to >1100 km were observed during upstream homing migrations of radio‐tagged spring chinook salmon Oncorhynchus tshawytscha in the Columbia and Snake Rivers, U.S.A. Downstream migrants, identified by their repeated ascension and fallback over a series of large hydroelectric dams within the migration corridor, were primarily hatchery‐origin males.