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223 records · Page 13Linked to original sources

Perspectives: Gene Expression in Fisheries Management

Functional genes and gene expression have been connected to physiological traits linked to effective production and broodstock selection in aquaculture, selective implications of commercial fish harvest, and adaptive changes reflected in non-commercial fish populations subject to human disturbance and climate change. Gene mapping using single nucleotide polymorphisms (SNPs) to identify functional genes, gene expression (analogue microarrays and real-time PCR), and digital sequencing technologies looking at RNA transcripts present new concepts and opportunities in support of effective and sustainable fisheries. Genomic tools have been rapidly growing in aquaculture research addressing aspects of fish health, toxicology, and early development. Genomic technologies linking effects in functional genes involved in growth, maturation and life history development have been tied to selection resulting from harvest practices. Incorporating new and ever-increasing knowledge of fish genomes is opening a different perspective on local adaptation that will prove invaluable in wild fish conservation and management. Conservation of fish stocks is rapidly incorporating research on critical adaptive responses directed at the effects of human disturbance and climate change through gene expression studies. Genomic studies of fish populations can be generally grouped into three broad categories: 1) evolutionary genomics and biodiversity; 2) adaptive physiological responses to a changing environment; and 3) adaptive behavioral genomics and life history diversity. We review current genomic research in fisheries focusing on those that use microarrays to explore differences in gene expression among phenotypes and within or across populations, information that is critically important to the conservation of fish and their relationship to humans.

Current Zoology↗

Non-lethal sampling for the detection of Myxobolus cerebralis in asymptomatic rainbow trout

We have described in previous reports (Schill et al., 1998) the development of a polymerase chain reaction (PCR) amplification of 18S ribosomal RNA for the detection of Myxozoan parasites. Oligonucleotide primers were developed by multiple alignment of Myxozoan sequence information and analysis by a custom-written computer program (PRIM). Candidate pairs of primer sequences were then analyzed for specificity by BLAST (Basic Local Alignment Search Tool). From these, a set of promising primers (MYXFWD and MYXREV) was chosen for further testing. These were chosen because they should direct detection of a number of Myxozoan species (Table 1). PCR using MXYFWD and MYXREV proved to be robust and relatively free of artifact products. Further, we were able to routinely detect Myxobolus cerebralis in fish tissues (Figure 1).

Book↗

Use of Dry Tortugas National Park by threatened and endangered marine turtles

Satellite and acoustic tracking results for green turtles, hawksbills, and loggerheads have revealed patterns in the proportion of time that tagged turtles spend within various zones of the park, including the RNA. Green turtles primarily utilize the shallow areas in the northern portion of the park. Hawksbills were mostly observed near Garden Key and loggerheads were observed throughout DRTO. Our record of turtle captures, recaptures, and sightings over the last 4 years serves as a baseline database for understanding the size classes of each species present in the park, as well as species-specific habitats in DRTO waters.

Florida↗

Spawning salmon and the fitness of stream-dwelling fishes: Marine-derived nutrients show saturating effects on growth and energy storage in juvenile salmonids

We examined how marine-derived nutrients (MDN), in the form of spawning Pacific salmon, influenced the nutritional status and d15N of stream-dwelling fishes. We sampled juvenile coho salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) during spring and fall from 11 south-central Alaskan streams that ranged widely in spawning salmon biomass (0.1–4.7 kg•m–2). Growth rate (as indexed by RNA–DNA ratios), energy density, and d15N enrichment in spring-sampled fishes increased with spawner biomass, indicating the persistence of spawner effects more than 6 months after salmon spawning. Point estimates suggest that spawner effects on nutrition were substantially greater for coho salmon than Dolly Varden (268% and 175% greater for growth and energy, respectively), indicating that both species benefitted physiologically, but that juvenile coho salmon accrued more benefits than Dolly Varden. Although the data were less conclusive for fall- than spring-sampled fish, they do suggest spawner effects were also generally positive during fall, soon after salmon spawned. In a follow-up analysis where growth rate and energy density were modeled as a function of d15N enrichment, results suggested that both increased with MDN assimilation, especially in juvenile coho salmon. Our results support the importance of salmon runs to the nutritional ecology of stream-dwelling fishes.

Canadian Journal of Fisheries and Aquatic Sciences↗

Response of salmonid fish to artificial infection with chum salmon virus

In the fall of 1978, a reovirus was isolated from normal-appearing adult chum salmon (Oncorhynchus keta ) returning to the Tokushibetsu Hatchery in Hokkaido, Japan (Winton et al 1981). The chum salmon virus (CSW) was recovered in the chinook salmon ( Oncorhynchus tshawytscha ) embryo cell line (CHSE-214) where it replicated at 15-20 C, producing foci of syncytia in the monolayer. Electron microscopy revealed icosahedral particles, 75 nm in diameter, with a double capsid. The virus was not inactivated by chloroform or inhibited by fluorodeoxyuridine. It was unstable at 56 C, did not hemagglutinate human type 0 erythrocytes, and had a density of 1.33 g/ml in CsCl . The virus was not neutralized by antiserum against infectious pancreatic necrosis virus or mammalian reovirus serotypes 1, 2 or 3 (Winton 1981). Electrophoretic analysis showed the genome was composed of three large, three medium, and five small segments of double stranded RNA (dsRNA) that ranged from 0.37-2.5 x 10% molecular weight. The virions contained five major structural proteins and several minor proteins (Winton et al 1983).

Book chapter↗

Isolation of a reovirus from coho salmon ( Oncorhynchus kisutch ) in Oregon, USA

Reoviruses isolated from aquatic animals share certain common characteristics: (1) a typical reovirus-like morphology which shows an icosahedral particle with a double capsid that is approximately 75 nm in diameter; (2) a genome with eleven segments of double-stranded RNA (dsRNA) distributed as three large, three medium and five small segments with a total molecular weight of approximately 15 x 106; (3) a virion composed of five major and several minor structural proteins that range in molecular weight from 32,000 to 137,000; and (4) form plaque-like syncytia in monolayer cultures of fish cells. Intact virus particles have buoyant densities in CsCl of 1.34 to 1.36 g/ml. The viruses have been isolated from fish and shellfish collected in both the marine and freshwater environments and will replicate in several fish cell lines (Plumb et al., 1979; Meyers and Hirai, 1980; Winton et al., 1981; Nagabayashi and Mori, 1983; Hedrick et al., 1984; Chen and Jiang, 1984). The original four aquatic reovirus isolates have been compared by Winton et al., 1987.

Book chapter↗

A ribonuclease protection assay can distinguish spring viremia of carp virus from pike fry rhabdovirus

Thirteen rhabdovirus isolates from 10 teleost fish species as well as reference strains of spring viraemia of carp virus (SVCV) and pike fry rhabdovirus (PFRV) cross-reacted in an indirect immunofluorescence assay and were thus indistinguishable by this method. A ribonuclease protection assay (RPA) using a super(32)P-labeled RNA probe made from a cloned copy of the full length SVCV glycoprotein (G) gene was able to discriminate clearly between the type strains of SVCV and PFRV and among the 13 rhabdovirus isolates. Results for the RPA were generally in agreement with standard serum neutralisation assays; however, the RPA was also able to detect genomic differences between isolates of SVCV. These results have implications for fish disease control programs for SVCV.

Bulletin of the European Association of Fish Patho↗