Genetic variation of flesh colour in canthaxanthin fed rainbow trout

Genetic experiments were conducted using either random independent full-sib families (9 and 11 respectively) or sire-half-sib families (18) of rainbow trout who were fed an experimental diet supplemented with canthaxanthin. The resulting orange-red colour of the flesh from each fish was analyzed through spectrophotometry and expressed in standard terms of luminosity (Y), dominant wavelength (λd) and excitation purity (Pe). The following results were obtained : - There is a substantial genetic variability among families in each colorimetric parameter. Estimated values of heritability from full-sib and from half-sib families do not differ significantly. - Positive correlation between λd . and Pe, and negative correlations between Y and λd and between Y and Pe, are consistent with the pattern of canthaxanthin deposition in the flesh. Genetic correlations do not differ significantly from phenotypic ones. - Pigmentation intensity is correlated to fish weight. This relationship, however, accounts for but a minor part of colour variation among market-size fishes.Des expériences génétiques ont été réalisées chez la Truite arc-en-ciel sur des familles aléatoires et indépendantes de pleins-frères (au nombre de 9 et 11) ou demi-frères de pères (18), alimentées par un régime expérimental supplémenté en canthaxanthine. La couleur de chair orange-rouge obtenue chez chaque poisson a été analysée par spectrophotométrie et exprimée en termes standards de luminosité (Y), longueur d’onde dominante (λd) et pureté d’excitation (Pe). Les résultats obtenus sont les suivants : - Il y a une variabilité génétique notable entre familles pour chaque paramètre colorimétrique. Les valeurs d’héritabilité estimées à partir des familles de plein-frères et de demi-frères ne diffèrent pas significativement. - Les corrélations, positives entre λd et Pe et négatives entre Y et λd et entre Y et Pe, sont conformes au mode d’action de la canthaxanthine se déposant dans la chair. Les corrélations génétiques ne diffèrent pas significativement de leurs homologues phénotypiques. - L’intensité de la pigmentation est corrélée avec le poids des poissons. Cette relation toutefois n’explique qu’une part minime de la variation de couleur chez des animaux de taille marchande

Effect of dietary bile extracts on serum response of astaxanthin in rainbow trout (Oncorhynchus mykiss): a preliminary study

Effects of porcine bile extracts added at three different dietary concentrations 0, 10 and 20 g kg)1 were studied on astaxanthin serum concentration in rainbow trout (mean weight 200 ± 7 g). Astaxanthin from micro-algae Haematococcus pluvialis and synthetic astaxanthin (CAROPHYLL pink) were incorporated in diets of rainbow trout at a rate of 100 mg astaxanthin kg)1 of feed. Fish were hand fed twice a day. After 5 days of feeding there was a significant effect of the pigment source on the ratio (total blood astaxanthin per unit body weight to cumulative astaxanthin intake per unit body weight). Trout receiving synthetic astaxanthin showed a significantly (P < 0.05) higher ratio than trout fed algal astaxanthin. Increasing dietary bile extract did not lead to produce any effect on this ratio. The power of the statistical analysis is discussed. Therefore, the interaction (pigment source · dietary bile concentration) showed no more effect

Effect of carotenoid source and dietary lipid content on blood astaxanthin concentration in rainbow trout (Oncorhynchus mykiss)

Astaxanthin concentration in the blood of rainbow trout was studied in a feeding trial with two different astaxanthin sources: green algae Haematococcus pluvialis and commercial beadlets of 8% astaxanthin content (CAROPHYLL® Pink), and two different dietary lipid levels. The green algae contained 1.4% of carotenoids on a dry matter basis: free astaxanthin (<1%), astaxanthin monoester (24.3%); astaxanthin diester (70.2%) and lutein (4.8%). Algal biomass was mechanically ground to disrupt the cell wall before incorporation in the feed. Hydrolysis of astaxanthin esters from algae occurred during the pelletization even at a low process temperature (43°C). Rainbow trout with an initial mean body weight of 150 g were fed experimental diets supplemented at a rate of 100 mg pigment/kg diet combined with two different lipid levels (9 and 24%) during 5 days. Astaxanthin concentration in the serum ranged from 5.3 μg/ml (8.9 nmol/ml) to 9.0 μg/ml (15.1 nmol/ml). Astaxanthin concentration in the serum was higher for fish fed high lipid level diets, independently of the astaxanthin source. No differences in the astaxanthin serum concentration were found for fish fed diets supplemented with either natural or synthetic astaxanthin, respectively 9.0±1.9 and 8.4±2.4 μg astaxanthin/ml serum, when dietary lipid level was high (24%). On the other hand, there was a higher blood astaxanthin concentration in fish fed diets supplemented with algal biomass (7.0±2.4 μg astaxanthin/ml serum) compared to synthetic astaxanthin (5.3±2.0 μg astaxanthin/ml serum) when dietary lipid level was low (9%

Evolution of the ridges of Midelt-Errachidia section in the High Atlas revealed by paleomagnetic data

New paleomagnetic data (43 sites) from Mesozoic sediments are contributed in this work, verifying the presence of a pervasive syntectonic Early Cretaceous remagnetization in the easternmost area of the Moroccan High Atlas. Using the small circle intersection method, we have calculated the characteristic remagnetization direction (Dec: 337.3, Inc: 38.4) that fits with a 100-Ma age, according to the Apparent Polar Wander Path of Africa. The paleomagnetic vectors of remagnetization are used to obtain the geometry during the remagnetization stage (100Ma) of one of the most renowned geological cross sections of the High Atlas, the Midelt-Errachidia profile. The partial restoration of the cross section at 100Ma allows us to determine the dips of the beds at the remagnetization stage in five structures (ridges or anticlines). Our results indicate that the five ridges that configure the Midelt-Errachidia profile were initiated to different degrees prior to wholesale compressive deformation during the Cenozoic. This configuration can be explained according to two different scenarios that we discuss in this paper: transpression and diapirism. The geological model obtained, both at present and at 100Ma, indicates the existence of a Mesozoic cover substantially decolled from the Paleozoic basement, what strongly contrasts with previously published transects of the same area

Constraints on Energy Intake in Fish: The Link between Diet Composition, Energy Metabolism, and Energy Intake in Rainbow Trout

The hypothesis was tested that fish fed to satiation with iso-energetic diets differing in macronutrient composition will have different digestible energy intakes (DEI) but similar total heat production. Four iso-energetic diets (2×2 factorial design) were formulated having a contrast in i) the ratio of protein to energy (P/E): high (HP/E) vs. low (LP/E) and ii) the type of non-protein energy (NPE) source: fat vs. carbohydrate which were iso-energetically exchanged. Triplicate groups (35 fish/tank) of rainbow trout were hand-fed each diet twice daily to satiation for 6 weeks under non-limiting water oxygen conditions. Feed intake (FI), DEI (kJ kg−0.8 d−1) and growth (g kg−0.8 d−1) of trout were affected by the interaction between P/E ratio and NPE source of the diet (P<0.05). Regardless of dietary P/E ratio, the inclusion of carbohydrate compared to fat as main NPE source reduced DEI and growth of trout by ∼20%. The diet-induced differences in FI and DEI show that trout did not compensate for the dietary differences in digestible energy or digestible protein contents. Further, changes in body fat store and plasma glucose did not seem to exert a homeostatic feedback control on DEI. Independent of the diet composition, heat production of trout did not differ (P>0.05). Our data suggest that the control of DEI in trout might be a function of heat production, which in turn might reflect a physiological limit related with oxidative metabolism

The African Landscape through Space and Time

It is generally accepted that Cenozoic epeirogeny of the African continent is moderated by convective circulation of the mantle. Nevertheless, the spatial and temporal evolution of Africa's “basin-and-swell” physiography is not well known. Here we show how continental drainage networks can be used to place broad constraints on the pattern of uplift through space and time. First, we assemble an inventory of 710 longitudinal river profiles that includes major tributaries of the 10 largest catchments. River profiles have been jointly inverted to determine the pattern of uplift rate as a function of space and time. Our inverse model assumes that shapes of river profiles are controlled by uplift rate history and modulated by erosional processes, which can be calibrated using independent geologic evidence (e.g., marine terraces, volcanism and thermochronologic data). Our results suggest that modern African topography started to develop ∼30 Myr ago when volcanic swells appeared in North and East Africa. During the last 15–20 Myr, subequatorial Africa was rapidly elevated, culminating in the appearance of three large swells that straddle southern and western coasts. Our results enable patterns of sedimentary flux at major deltas to be predicted and tested. We suggest that the evolution of drainage networks is dominated by rapid upstream advection of signals produced by a changing pattern of regional uplift. An important corollary is that, with careful independent calibration, these networks might act as useful tape recorders of otherwise inaccessible mantle processes. Finally, we note that there are substantial discrepancies between our results and published dynamic topographic predictions

Kinematic and thermal evolution of the Moroccan rifted continental margin: Doukkala-High Atlas Transect

The Atlantic passive margin of Morocco developed during Mesozoic times in association with the opening of the Central Atlantic and the Alpine Tethys. Extensional basins formed along the future continental margin and in the Atlas rift system. In Alpine times, this system was inverted to form the High and Middle Atlas fold-and-thrust belts. To provide a quantitative kinematic analysis of the evolution of the rifted margin, we present a crustal section crossing the Atlantic margin in the region of the Doukkala Basin, the Meseta and the Atlas system. We construct a post-rift upper crustal section compensating for Tertiary to present vertical movements and horizontal deformations, and we conduct numerical modeling to test quantitative relations between amounts and distribution of thinning and related vertical movements. Rifting along the transect began in the Late Triassic and ended with the appearance of oceanic crust at 175 Ma. Subsidence, possibly related to crustal thinning, continued in the Atlas rift in the Middle Jurassic. The numerical models confirm that the margin experienced a polyphase rifting history. The lithosphere along the transect preserved some strength throughout rifting with the Effective Elastic Thickness corresponding to an isotherm of 450°C. A mid-crustal level of necking of 15 km characterized the pre-rift lithosphere. © 2010 by the American Geophysical Union