Histidine nutrition and genotype affect cataract development in Atlantic salmon, <i>Salmo salar</i> L.

Breck, Olav; Bjerkås, Ellen; Campbell, Patrick; Rhodes, Jeremy D.; Sanderson, Julie; Waagbø, Rune

doi:10.1111/j.1365-2761.2005.00640.x

Cited by 77 publications

(131 citation statements)

References 44 publications

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“…The early part of salmon development is spent in freshwater as parr followed by transformation to smolts before entering the sea. Despite the physiological changes associated with parr-smolt transformation, a preadaption for life in seawater, reversible osmotic cataracts, are commonly described immediately after seawater transfer (9, 22), and irreversible cataracts, which also develop soon after transfer, are often seen in seawater fish (7,9,31). There is additional evidence that osmotic stress may cause cataract in farmed salmon since the appearance of cataract was shown to be increased by environmental fluctuations in salinity (4).…”

mentioning

confidence: 99%

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

Rhodes

Breck²,

Waagbø³

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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-Volume homeostasis is essential for the preservation of lens transparency and this is of particular significance to anadromous fish species where migration from freshwater to seawater presents severe osmotic challenges. In Atlantic salmon (Salmo salar L.), aqueous humor (AH) osmolality is greater in fish acclimated to seawater compared with young freshwater fish, and levels of lens N-acetylhistidine (NAH) are much higher in seawater fish. Here we investigate NAH as an osmolyte in the lenses of salmon receiving diets either with or without histidine supplementation. In the histidine-supplemented diet (HD) histidine content was 14.2 g/kg, and in the control diet (CD) histidine content was 8.9 g/kg. A transient increase in AH osmolality of 20 mmol/kg was observed in fish transferred from freshwater to seawater. In a lens culture model, temporary decreases in volume and transparency were observed when lenses were exposed to hyperosmotic conditions. A positive linear relationship between extracellular osmolality and lens NAH content was also observed, whereas there was no change in lens histidine content. Hypoosmotic exposure stimulated [ 14 C]-histidine efflux by 9.2-and 2.6-fold in CD and HD lenses, respectively. NAH efflux, measured by HPLC, was stimulated by hypoosmotic exposure to a much greater extent in HD lenses. In vivo, lens NAH increased in response to elevated AH osmolality in HD but not CD fish. In conclusion, NAH has an important and novel role as a compatible osmolyte in salmon lens. Furthermore, it is the major osmolyte that balances increases in AH osmolality when fish move from freshwater to seawater. A deficiency in NAH would lead to a dysfunction of the normal osmoregulatory processes in the lens, and we propose that this would contribute to cataract formation in fish deficient in histidine. histidine PREVALENCE OF CATARACT IN farmed Atlantic salmon (Salmo salar L.) has increased in recent years (3) and this has been linked to the removal of a rich source of dietary histidine (blood meal) (7). Several recent studies have investigated the possible causes of cataract in farmed salmon (6, 9, 30), although the mechanisms involved remain to be elucidated.Osmotic stress has been shown to contribute to cataract formation in multiple species, including man (19). Efficient volume regulation is crucial for the maintenance of lens transparency and disruption to the tightly packed and highly ordered cells and proteins that make up the lens will cause a loss of lens transparency. In fish there are numerous examples where osmotic factors have been shown to play a role in cataract development (20), and the anadromous life cycle of the Atlantic salmon exposes the fish to particularly severe osmotic stress. The early part of salmon development is spent in freshwater as parr followed by transformation to smolts before entering the sea. Despite the physiological changes associated with parr-smolt transformation, a preadaption for life in seawater, reversible osmotic cataracts, are commonly described immediately aft...

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mentioning

confidence: 99%

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

Rhodes

Breck²,

Waagbø³

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…insufficient dietary His supply), the lens may utilise other osmolytes. Breck et al (2005a), for example, showed that the sum of free amino acids in Atlantic salmon lenses was relatively constant, despite variations in the concentration of NAH induced by different diets. The results of the present study suggest, however, that utilisation of NAH might be more efficient in lens osmoregulation than efflux of other amino acids to compensate for low His and NAH concentrations, as the P-lenses showed a greater volume change than did the M-lenses.…”

Section: Discussionmentioning

confidence: 99%

“…The osmolality of the control medium was chosen to equate to the aqueous humour osmolality in vivo, previously measured by (Breck et al, 2005a). Medium osmolality was adjusted by addition of either NaCl or de-ionised Milli-Q water (Millipore, Billerica, USA).…”

Section: Lens Culture and Osmotic Challengementioning

confidence: 99%

“…Histidine (His) and N-acetylhistidine (NAH) concentrations in lenses and culture medium were analysed by isocratic reverse phase HPLC with UV absorbance at 210 nm, using external standard calibration, as previously described by Breck et al (2005a). No NAH , respectively.…”

Section: Biochemical Analysismentioning

confidence: 99%

“…Elevated levels of His in the fish diet have been found to be reflected in the lens concentration of the His-derivative Nacetylhistidine (NAH), and to prevent or slow the progression of cataract development in Atlantic salmon (Breck, 2004;Breck et al, 2003;2005a;b;Tröβe et al, 2008;. The mechanism by which NAH protects the lens, however, is not clear.…”

Section: Introductionmentioning

confidence: 99%

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Effect of plant-based feed ingredients on osmoregulation in the Atlantic salmon lens

Tröβe¹,

Rhodes

Sanderson

et al. 2010

Comparative Biochemistry and Physiology Part B: Biochemistry an

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Lenses of adult Atlantic salmon fed with a plant oil and plant protein-based diet (plant diet) were compared to lenses of fish fed a diet based on traditional marine ingredients (marine diet) with respect to biochemical composition and functionality ex vivo. After 12 months of feeding, plant diet-fed fish had smaller lenses with higher water contents and lower concentrations of histidine (His) and N-acetylhistidine (NAH) than fish fed with the marine diet. Cataract development in both dietary groups was minimal and no differences between the groups were observed. Lens fatty acid and lipid class composition differed minimally, although a significant increase in linoleic acid was observed. The lenses were examined for their ability to withstand osmotic disturbances ex vivo. Culture in hypoosmotic and hyperosmotic media led to increase and decrease of lens volume, respectively. Lenses from plant diet-fed fish were less resistant to swelling and shrinking, released less NAH into the culture medium, and accumulated His and NAH at higher rates than lenses from marine diet-fed fish. Culture in hypoosmotic medium resulted in higher cataract scores than in control and hyperosmotic medium. mRNA expression of selected genes, including glutathione peroxidase 4 and SPARC (secreted protein acidic and rich in cysteine), was affected by diet and osmotic treatment. It can be concluded that lenses of farmed Atlantic salmon are affected by the diet composition, both in biochemical composition and physiological functionality in relation to osmoregulation.

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Fish Disease

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Histidine nutrition and genotype affect cataract development in Atlantic salmon, Salmo salar L.

Cited by 77 publications

References 44 publications

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

Effect of plant-based feed ingredients on osmoregulation in the Atlantic salmon lens

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