Antioxidant vitamins, minerals and lipid levels in diets for Atlantic salmon (Salmo salar, L.): effects on growth performance and fillet quality

An experiment with 2^{(7 ? 3)} reduced factorial design was conducted to study the biological effects of pro‐ and antioxidant micronutrients and lipid in Atlantic salmon. Vitamins C and E, astaxanthin, lipid, iron, copper and manganese were supplemented at high and low levels. For vitamins and minerals, high levels were chosen to be below the anticipated toxic level and the low levels were just above the requirement (vitamin C, 30 and 1000 mg kg^?1; vitamin E, 70 and 430 mg kg^?1; Fe, 70 and 1200 mg kg^?1; Cu, 8 and 110 mg kg^?1; Mn, 12 and 200 mg kg^?1). For astaxanthin, the dietary levels were 10 and 50 mg kg^?1 and for lipid, 150 and 330 g kg^?1. The experiment was started with postsmolts (148 ± 17 g) and lasted for 5 months. The variation in micronutrients had only minor effects on growth, feed conversion and fillet quality, measured as lipid and astaxanthin deposition. High dietary lipid had a profound positive effect on growth and feed conversion but gave fillets nearly two times the fat content that was found in fish fed the low lipid diet. Astaxanthin deposition in the fillet was primarily affected by dietary astaxanthin with a positive effect of high dietary lipid in week 14 but not in week 23. Vitamin E protected the fillet against iron ascorbate stimulated oxidation, with no effect of the other nutrient variables.     

Explaining spatial variability in stream habitats using both natural and management‐influenced landscape predictors

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The effects of prolonged exercise training on growth performance and production parameters in fish

When juvenile salmonids are reared in water flowing with currents equivalent to swimming speeds of about 0.75–1.5 BL s^–1, the fish tend to grow faster and make more efficient use of the food provided than do conspecifics held in standing water. There may be a more even distribution of food within a group of exercised fish leading to uniformity of growth rates and a reduced size range of the fish at harvest. In addition, frequencies of aggressive interactions may be lower in exercised fish than in those reared in standing water, leading to fewer exercised fish having fin damage. Thus, several benefits may be expected to accrue from growing salmonids in flowing water. The training of salmonids by exposing them to moderate water currents for prolonged periods leads to improvements in physiological performance, so rearing such fish in flowing, rather than standing, water may be particularly beneficial when they are destined for release in connection with restocking or ranching programmes.     

Human CHN1 mutations hyperactivate alpha2-chimaerin and cause Duane's retraction syndrome

Duane's retraction syndrome (DRS) is a complex congenital eye movement disorder caused by aberrant innervation of the extraocular muscles by axons of brainstem motor neurons. Studying families with a variant form of the disorder (DURS2-DRS), we have identified causative heterozygous missense mutations in CHN1, a gene on chromosome 2q31 that encodes alpha2-chimaerin, a Rac guanosine triphosphatase-activating protein (RacGAP) signaling protein previously implicated in the pathfinding of corticospinal axons in mice. We found that these are gain-of-function mutations that increase alpha2-chimaerin RacGAP activity in vitro. Several of the mutations appeared to enhance alpha2-chimaerin translocation to the cell membrane or enhance its ability to self-associate. Expression of mutant alpha2-chimaerin constructs in chick embryos resulted in failure of oculomotor axons to innervate their target extraocular muscles. We conclude that alpha2-chimaerin has a critical developmental function in ocular motor axon pathfinding.     

Systemic Concentrations of Endogenous and Exogenous FSH in Anoestrous Ewes Superstimulated with Folltropin®-V

The synchronization of follicular waves with medroxyprogesterone acetate (MAP) and oestradiol‐17β (E₂‐17β) prior to ovarian superstimilation in anoestrous ewes reduces the variability in superovulatory responses by an unknown mechanism. Follicle stimulating hormone (FSH) is a primary promoter of antral follicular development, but the relevance of circulating FSH concentrations to the superovulation performance in ewes has not been examined. Eighteen anoestrous Rideau Arcott ewes (May–June) were superovulated with Folltropin^®‐V (porcine FSH), with (n = 8; treated ewes) or without (n = 10; control ewes) a single i.m. dose of 350 μg of E₂‐17β, given on the sixth day of a 14‐day treatment with MAP‐releasing intravaginal sponges (60 mg). The superovulatory treatment, begun 6 days after E₂‐17β injection, consisted of six i.m. applications of Folltropin^®‐V given twice daily (at 08:00 and 16:00 h), followed by an i.m. injection of GnRH (50 μg). Blood samples collected every 8 h throughout the 3‐day treatment, were analysed by radioimmunoassays for concentrations of ovine and porcine FSH, using species‐specific standards and primary antibodies. Serum concentrations of oFSH were greater (p < 0.05) in the controls compared to treated ewes at 40, 64 and 72 h and the variability in mean oFSH concentrations was greater (p < 0.05) in control ewes at 40, 48, 64 and 72 h after the 1^st Folltropin^®‐V injection. There were no differences (p > 0.05) between the two groups in serum concentrations of pFSH. Significant correlations were recorded between the number of corpora lutea (CL) and oFSH concentrations at 8 h (r = 0.72, p < 0.05), 16 h (r=0.63, p < 0.05) and 64 h (r = 0.84, p < 0.01) after the 1^st Folltropin^®‐V injection. The total number of recovered embryos was positively correlated to oFSH concentrations at 56 h (r = 0.69, p < 0.05). We concluded that changes in endogenous FSH concentrations during ovarian superstimulation with pFSH might contribute to the variability in superovulatory responses in ewes.