Juan Manuel Afonso

Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain

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Publications (7)8.4 Total impact

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    ABSTRACT: The high number of multiplex PCRs developed for gilthead seabream (Sparus aurata L.) from many different microsatellite markers does not allow comparison among populations. This highlights the need for developing a reproducible panel of markers, which can be used with safety and reliability by all users. In this study, the first standardised panel of two new microsatellite multiplex PCRs was developed for this species. Primers of 138 specific microsatellites from the genetic linkage map were redesigned and evaluated according to their genetic variability, allele size range and genotyping reliability. A protocol to identify and classify genotyping errors or potential errors was proposed to assess the reliability of each marker. Two new multiplex PCRs from the best assessed markers were designed with 11 markers in each, named SMsa1 and SMsa2 (SuperMultiplex Sparus aurata). Three broodstocks (59, 47 and 98 breeders) from different Spanish companies, and a sample of 80 offspring from each one, were analysed to validate the usefulness of these multiplexes in the parental assignation. It was possible to assign each offspring to a single parent pair (100% success) using the exclusion method with SMsa1 and/or SMsa2. In each genotyped a reference sample (Ref-sa) was used, and its DNA is available on request similar to the kits of bin set to genotype by genemapper (v.3.7) software (kit-SMsa1 and kit-SMsa2). This will be a robust and effective tool for pedigree analysis or characterisation of populations and will be proposed as an international panel for this species.
    Animal Genetics 04/2013; · 2.58 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate growth, biochemical composition and dietary nutrients utilization in O ctopus vulgaris fed on four diets based on bogue B oops boops, from different origin and in two presentations: fresh discarded bogue (aquaculture by‐product) (DB‐f), fresh wild bogue (low price trash species) (WB‐f), discarded bogue agglutinated moist diet (DB‐m) and wild bogue agglutinated moist diet (WB‐m). Diets based on DB showed higher lipid content (19–26% dw) than those based on WB (5–6% dw). Octopuses fed on DB‐based diets showed higher growth (1.5–1.9% day−1) and higher protein efficiency ratio (0.64–0.69) than those fed on WB‐based diet (1.1–1.5% day−1 and 0.36–0.37 respectively), which suggests good utilization of dietary lipids and also a possible protein sparing effect by lipids in O . vulgaris. Octopuses fed on diets presented fresh showed a higher growth (1.9–1.5% day−1) and a higher feed efficiency (62–65%) than those fed on agglutinated diets (1.1–1.5% and 52–60% day−1 respectively). Regarding fatty acids, the digestive gland clearly reflected dietary lipid and fatty acid profile, while muscle showed a more stable composition. Low dietary ARA content reflected in octopus tissues, especially in specimens fed on DB‐based diets, which did not seem to affect growth during the experimental period.
    Aquaculture Research 12/2012; 44(1). · 1.42 Impact Factor
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    ABSTRACT: The physiological response to stressors in fish, including hormonal profiles and associated tissue responsiveness, is less documented. The aim of this study was to evaluate feeding gilthead sea bream (Sparus aurata) with diets containing linseed oil (LO) and soybean oil (SO) as substitutes to fish oil (FO) and their effect on fatty acid profile of head kidney and the consequent effect on stress response to a crowding challenge. Fish were fed 8 experimental diets with different levels of substitution 0% (FO), 70% (70LO, 70SO, 20LO50SO and 50LO20SO) and 100% (100LO, 100SO and 50LO50SO) over a period of 8 months. At the end of the feeding trial, samples of head kidney were collected for biochemical analysis and the fish were challenged by a crowding test. During the challenge, samples of plasma for cortisol analysis were collected at 0 h, 2 h, 5 h, 24 h, 48 h and 1 week in order to study acute and chronic stress responses. Results showed that fish fed vegetable oils (VO) had significantly decreased ARA, EPA, DHA and n-3 HUFA, while LA, LNA and total C18 PUFAs were significantly increased. The basal cortisol levels were significantly increased in fish fed 70LO, 100LO, 50LO20SO and 50LO50SO. The physiological response to crowding was significantly affected by the diet. After 2 h of crowding, all the treatments showed higher cortisol, with fish fed 100LO had significantly the highest response registering 131.38 pg/ml. After 5 h and 24 h, plasma cortisol was reduced in all treatments except in 50LO20SO. After 48 h of crowding, the plasma cortisol was increased in all treatments with the maximum value seen in fish fed 100LO (72.12 pg/ml). These levels were decreased in fish fed FO, 70LO, 100LO and 50L050SO after 1 week of crowding, but remained higher in fish fed 70SO, 100SO, 20LO50SO and 50LO20SO. In conclusion, fish fed LO diets showed the same response pattern as the control but with higher intensity regaining the basal levels after 1 week as the control, while fish fed SO had a slow response but changed the pattern characterized by a lower response at the beginning and longer recuperation without regaining the control value even after 1 week.
    Aquaculture. 01/2011; 311:215-223.
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    ABSTRACT: The Delta6 and Delta5 desaturases and elongases show only very limited activity in marine fish, and little is known of the possibility of enhancing Delta6 desaturase gene expression in these fish. The use of plant oils in marine fish diets is limited by their lack of n-3 highly unsaturated fatty acids (HUFA) despite an abundant content of the 18C fatty acid precursor linoleic and alpha-linolenic acids. The objective of the present study was to determine the ability of larval gilthead seabream to utilize vegetable oils and assess the nutritional regulation of Delta6 desaturase gene expression. Seventeen-day-old gilthead seabream larvae were fed during a 17-day period with one of four different microdiets formulated with either sardine fish oil (FO), soybean, rapeseed or linseed oils, respectively, or a fifth diet containing defatted squid meal and linseed oil. Good larval survival and growth, both in terms of total length and body weight, were obtained by feeding the larvae either rapeseed, soybean or linseed oils. The presence of vegetable oils in the diet increased the levels of 20:2n-9 and 20:2n-6, 18:2n-9, 18:3n-6, 20:3n-6 and 20:4n-6, in larvae fed rapeseed and soybean oils in comparison to those fed FO. In addition, a sixfold increase in the relative expression of Delta6 desaturase-like gene was found in larvae fed rapeseed and soybean oils, denoting the nutritional regulation of desaturase activity through its gene expression in this fish species. However, feeding linseed oil did not increase the expression of the Delta6 desaturase gene to such a high extent.
    Fish Physiology and Biochemistry 06/2008; 34(2):117-27. · 1.55 Impact Factor
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    ABSTRACT: This study reports two new and highly informative multiplex PCRs of microsatellite markers, with redesigned interspecific primer sets for three sparid species: gilthead seabream (Sparus auratus L.), red porgy (Pagrus pagrus L.) and redbanded seabream (P. auriga, Valenciennes, 1843). The evaluation and validation of the two multiplex PCRs, named RimA and RimB (Redesigned Interspecific Multiplex), were carried out upon: 148 individual gilthead seabream (66 breeders of unknown gender, and 82 of their descendents obtained by mass-spawning), 37 red porgy and 125 redbanded seabream. From 15 and 12 redesigned microsatellite markers for RimA and RimB, respectively, the number of markers included in the final multiplex PCRs were 10 in RimA and 7 in RimB for gilthead seabream, 6 in each multiplex PCR for red porgy and 8 in RimA and 5 in RimB for redbanded seabream. The a priori combined parental exclusion probability for each multiplex in the three species was 0.999. For gilthead seabream, it was possible to assign each offspring to a single parent pair (100% success) using the exclusion method with at least seven microsatellite markers for each multiplex PCR. Null alleles were found only for marker PbMS2, through familial segregation, with a frequency similar to the expected one (0.09 vs 0.14). Results revealed that the multiplex reaction no more than one-sixth the cost of single reactions even when these reactions were performed in a unique run, and that genotyping errors were minimized due to automation. These robust multiplex PCRs will be a fundamental tool for the industry to introduce selection programs and to manage their broodstocks under industrial conditions.
    Aquaculture. 01/2008;
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    ABSTRACT: The use of the fluorescent visible implant elastomer (VIE) tagging system in juvenile gilthead seabream, Sparus auratus L., between 7 and 18 g was examined. Four different colours (red, green, orange and yellow), three body positions (dorsal, lateral and caudal) and two orientations (horizontal and vertical) were tested. The mean tag application time for each fish was 15.7±0.32 s. There was no mortality associated with the method of tagging. The most visible tag colour was red. Injection orientation had a significant effect on length, width, fragmentation and fluorescent intensity of the tag. Horizontal tagging is recommended because of high fluorescent intensity, low fragmentation and for double tagging. There were no differences in growth between untagged controls and the VIE-tagged fish.
    Aquaculture Research 04/2005; 36(8):733 - 738. · 1.42 Impact Factor
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    ABSTRACT: Immature gilthead sea bream (Sparus aurata L.) with a mean initial weight of 25.6 g were reared over 11 months to market size under different photoperiods: 16L:8D; 24L:0D and a control. Differences in final mean weight were significant between the three treatments (P<0.001): 16L:8D, 465.0 g; 24L:0D, 445.9 g; control, 402.6 g. Fish from the 24L:0D consumed most while 16L:8D fish converted it most efficiently. The lipid content of fillets was lower (P<0.05) for the 24L:0D (5.37±0.16 g 100 g−1 of fillet) than for the control (6.02±0.12 g), and the moisture content lower for the control than for either treatment groups. Skin luminosity (L*) was directly related to the number of hours of light exposure.
    Aquaculture Research 07/2004; 35(13):1207 - 1212. · 1.42 Impact Factor