RESUMEN
Growth hormone (GH) transgenic salmon possesses markedly increased metabolic rate, appetite, and feed conversion efficiency, as well as an increased ability to compete for food resources. Thus, the ability of GH-transgenic fish to withstand periods of food deprivation as occurs in nature is potentially different than that of nontransgenic fish. However, the physiological and genetic effects of transgenic GH production over long periods of food deprivation remain largely unknown. Here, GH-transgenic coho salmon (Oncorhynchus kisutch) and nontransgenic, wild-type coho salmon were subjected to a 3-month food deprivation trial, during which time performance characteristics related to growth were measured along with proximate compositions. To examine potential genetic effects of GH-transgenesis on long-term food deprivation, a group of genes related to muscle development and liver metabolism was selected for quantitative PCR analysis. Results showed that GH-transgenic fish lose weight at an increased rate compared to wild-type even though proximate compositions remained relatively similar between the groups. A total of nine genes related to muscle physiology (cathepsin, cee, insulin-like growth factor, myostatin, murf-1, myosin, myogenin, proteasome delta, tumor necrosis factor) and five genes related to liver metabolism (carnitine palmitoyltransferase, fatty acid synthase, glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, glucokinase) were shown to be differentially regulated between GH-transgenic and wild-type coho salmon over time. These genetic and physiological responses assist in identifying differences between GH-transgenic and wild-type salmon in relation to fitness effects arising from elevated growth hormone during periods of long-term food shortage.
Asunto(s)
Animales Modificados Genéticamente/genética , Expresión Génica/fisiología , Hormona del Crecimiento/biosíntesis , Oncorhynchus kisutch/genética , Animales , Animales Modificados Genéticamente/metabolismo , Animales Modificados Genéticamente/fisiología , Composición Corporal/genética , Composición Corporal/fisiología , Femenino , Privación de Alimentos/fisiología , Expresión Génica/genética , Hormona del Crecimiento/genética , Hígado/metabolismo , Masculino , Músculo Esquelético/metabolismo , Oncorhynchus kisutch/metabolismo , Oncorhynchus kisutch/fisiologíaRESUMEN
The present study reports measured levels of organochlorine pesticides (OCPs) in commercial salmon feed (n = 8) and farmed Atlantic, coho, and chinook salmon (n = 110), as well as wild coho, chinook, chum, sockeye, and pink salmon (n = 91). Flesh residue concentrations (ng/g wet weight) of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), chlordanes, chlorobenzenes (CBz) and cyclodiene pesticides (e.g., dieldrin, mirex) were 2 to 11 times higher (p < 0.05) in farmed salmon compared with wild salmon. Concentrations were positively correlated with flesh lipid levels. Farmed Atlantic salmon (12-15% lipid) typically exhibited the greatest OCP burdens compared with other salmon species. However, when expressed on a lipid weight basis, concentrations of OCPs (ng/g lipid weight) in wild salmon, in many cases, exceeded those levels in farmed salmon. Observed interspecies and site-specific variations of OCP concentrations in farmed and wild salmon may be attributed to divergent life history, prey/feed characteristics and composition, bioenergetics, or ambient environmental concentrations. Calculated biomagnification factors (BMF = C(F)/C(D), lipid wt) of OCPs in farmed salmon typically ranged between two and five. Biomagnification of chemicals such as DDTs, chlordanes, and mirex was anticipated, because those compounds tend to exhibit high dietary uptake and slow depuration rates in fish because of relatively high octanol-water partition coefficients (K(OW)s > 105). Surprisingly, less hydrophobic pesticides such as hexachlorocyclohexanes and endosulfans (K(OW) s < 105) consistently exhibited a high degree of biomagnification in farmed salmon species (BMFs > 5). This is contrary to previous laboratory and field observations demonstrating fish BMFs less than 1 for low K(OW) chemicals, because of efficient respiratory elimination of those compounds via gills. The results suggest that ambient seawater concentrations and bioconcentration-driven accumulation may play a key role in the bioaccumulation of these relatively more water-soluble contaminants in farmed salmon. Finally, OCP exposure through consumption of British Columbian salmon is found to be low relative to United States national average per capita total exposure levels and provisional tolerable daily intakes.
Asunto(s)
Acuicultura , Hidrocarburos Clorados/análisis , Residuos de Plaguicidas/análisis , Salmón , Animales , Colombia Británica , Monitoreo del Ambiente , Geografía , Hidrocarburos Clorados/farmacocinética , Residuos de Plaguicidas/farmacocinética , Alimentos Marinos , Especificidad de la Especie , Estados UnidosRESUMEN
The present study is the first to simultaneously and continuously measure oxygen consumption (MO(2)) and gastrointestinal blood flow (q(gi)) in fish. In addition, while it is the first to compare the effects of three isoenergetic diets on q(gi) in fish, no significant differences among diets were found for postprandial MO(2), q(gi) or heart rate (f(H)) in rainbow trout, Oncorhynchus mykiss. Postprandial q(gi), f(H) and MO(2) were significantly elevated above baseline levels by 4 h. Postprandial q(gi) peaked at 136% above baseline after 11 h, f(H) peaked at 110% above baseline after 14 h and MO(2) peaked at 96% above baseline after 27 h. Moreover, postprandial MO(2) remained significantly elevated above baseline longer than q(gi) (for 41 h and 30 h, respectively), perhaps because most of the increase in MO(2) associated with feeding is due to protein handling, a process that continues following the absorption of nutrients which is thought to be the primary reason for the elevation of q(gi). In addition to the positive relationships found between postprandial MO(2) and q(gi) and between postprandial MO(2) and f(H), we discovered a novel relationship between postprandial q(gi) and f(H).
Asunto(s)
Gasto Cardíaco , Tracto Gastrointestinal/metabolismo , Frecuencia Cardíaca , Oncorhynchus mykiss/metabolismo , Consumo de Oxígeno , Periodo Posprandial/fisiología , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Digestión , Absorción IntestinalRESUMEN
The present study reports measured levels of Hg and other trace elements in commercial salmon feed; farmed Atlantic, coho, and chinook salmon (n = 110); and wild coho, chinook, chum, sockeye, and pink salmon (n = 91). Metal concentrations in farmed and wild salmon from British Columbia, Canada, were relatively low and below human health consumption guidelines. Methylmercury in all salmon samples (range, 0.03-0.1 microg/g wet wt) were below the 0.5 microg/g guideline set by Health Canada. Negligible differences in metal concentrations were observed between the various species of farmed and wild salmon. Metal concentrations generally were higher in commercial salmon feed compared to farmed salmon. Mercury showed slight bioaccumulation potential in farmed salmon, with biomagnification factors (BMFs) ranging between 0.8 and 1.9. Other metals, such as Cd, Pb, and Ni, exhibited biodilution, with BMFs of much less than one. The relatively low degree of biomagnification of metals observed in farmed salmon likely resulted from the combination of low gastrointestinal absorption efficiency, negligible transfer to muscle tissue relative to other compartments, and a high degree of growth dilution in these fish. Human dietary exposure calculations indicate intakes of Hg, Cd, Pb, Cu, As, and Ni via farmed and wild British Columbia salmon are a relatively small percentage of total intakes (0.05-32%) compared to other Canadian foodstuffs, such as fruits, vegetables, chicken, and beef (68-99%). Although total dietary exposure of Cd, Pb, and Cu approached provisional tolerable daily intake levels, the contribution from British Columbia salmon was less than 2%. Our findings indicate farmed and wild British Columbia salmon remain a safe source of omega-3 highly unsaturated fatty acid intake for cardioprotective and, possibly, other health benefits.
Asunto(s)
Animales Salvajes/metabolismo , Acuicultura , Mercurio/análisis , Salmón/metabolismo , Oligoelementos/análisis , Animales , Colombia Británica , Humanos , Mercurio/metabolismo , Oligoelementos/metabolismoRESUMEN
There is considerable concern that endocrine disrupting substances such as 4-nonylphenol (4-NP) in the freshwater environment may have adverse effects on the growth, survival, and osmoregulatory ability of salmonids during and after their transfer to sea water. This study was conducted to examine the effects of dietary exposure of coho salmon (Oncorhynchus kisutch) to 4-NP during the parr-smolt transformation phase of their life cycle. Under laboratory conditions, juvenile fish were fed by hand twice daily to satiation diets dosed with one of several concentrations of 4-NP (doses varied between 0 (control) and 2000 mg/kg) for 4 weeks, then immediately transferred to sea water. Growth was observed for two successive 6-week periods following sea water transfer when all groups were fed the control diet (no supplemental 4-NP) only. In addition to 4-NP measurement in fish tissues, thyroid hormone concentrations in blood plasma were followed and related to diet treatment and sampling time. Dietary treatment of 4-NP did not influence the growth and smoltification of coho salmon, a result that conflicts to some extent with other reports in which deleterious effects of water-borne 4-NP on the smoltification process of salmonids were linked to disruption of the endocrine system. Appreciable concentrations of 4-NP were present in the livers, gall bladders and tissues after the 4-week exposure of coho salmon to the highest dietary dose of 4-NP, but 4-NP appeared to be effectively eliminated from the fish by the biliary-fecal pathway after sea water transfer.
Asunto(s)
Disruptores Endocrinos/toxicidad , Oncorhynchus kisutch , Fenoles/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Dieta , Disruptores Endocrinos/análisis , Análisis de los Alimentos , Vesícula Biliar/química , Hígado/química , Músculos/química , Oncorhynchus kisutch/crecimiento & desarrollo , Oncorhynchus kisutch/metabolismo , Fenoles/análisis , Tiroxina/sangre , Triyodotironina/sangre , Contaminantes Químicos del Agua/análisisRESUMEN
This study was conducted to investigate the effect of dietary vitamin E concentration on growth performance, iron-catalyzed lipid peroxidation in liver and muscle tissue, and erythrocyte fragility of transgenic growth hormone coho salmon (Oncorhynchus kisutch). Fish were fed one of four isoenergetic and isonitrogenous experimental diets that contained either 11, 29, 50, or 105 IU of vitamin E/kg. Following the 10-week feeding trial, no significant (P>0.05) diet-related differences were detected in growth, whole body proximate composition or erythrocyte fragility. The vitamin E contents of liver and muscle, however, were affected by the dietary treatment. Fish fed diets containing > or =50 IU of vitamin E/kg had significantly increased vitamin E concentrations in their tissues. Iron-catalyzed lipid peroxidation of liver and muscle tissue of fish fed elevated dietary vitamin E (> or =50 IU vitamin E/kg diet) was significantly lower (P<0.05) than that noted for fish fed the diet containing no supplemental vitamin E. The results indicated that changes in tissue lipid peroxidation measurements precede clinical signs of sub-optimal vitamin E intake.