Transient Ectopic Overexpression of Agouti-Signalling

While flatfish in the wild exhibit a pronounced countershading of the dorso-ventral pigment pattern, malpigmentation is commonly observed in reared animals. In fish, the dorso-ventral pigment polarity is achieved because a melanization inhibition factor (MIF) inhibits melanoblast differentiation and encourages iridophore proliferation in the ventrum. A previous work of our group suggested that asip1 is the uncharacterized MIF concerned. In order to further support this hypothesis, we have characterized asip1 mRNAs in both turbot and sole and used deduced peptide alignments to analyze the evolutionary history of the agouti-family of peptides. The putative asip precursors have the characteristics of a secreted protein, displaying a putative hydrophobic signal. Processing of the potential signal peptide produces mature proteins that include an N-terminal region, a basic central domain with a high proportion of lysine residues as well as a proline-rich region that immediately precedes the C-terminal poly-cysteine domain. The expression of asip1 mRNA in the ventral area was significantly higher than in the dorsal region. Similarly, the expression of asip1 within the unpigmented patches in the dorsal skin of pseudoalbino fish was higher than in the pigmented dorsal regions but similar to those levels observed in the ventral skin. In addition, the injection/electroporation of asip1 capped mRNA in both species induced long term dorsal skin paling, suggesting the inhibition of the melanogenic pathways. The data suggest that fish asip1 is involved in the dorsalventral pigment patterning in adult fish, where it induces the regulatory asymmetry involved in precursor differentiation into mature chromatophore. Adult dorsal pseudoalbinism seems to be the consequence of the expression of normal developmental pathways in an inaccurate position that results in unbalanced asip1 production levels. This, in turn, generates a ventral-like differentiation environment in dorsal regions.Publicado

Growth under laboratory conditions of wild juvenile black-spot sea bream (Pagellus bogaraveo B.)

As an alternative to the culture of traditional fish, experiments have been started with black-spot sea bream (Pagellus bogaraveo) and are summarized here. Two groups of bream (B-1 and B-2) with 63 fish of mean weight 173 g and 67fish of mean weight 217 g, respectively, were captured on the NW coast of Spain between September and December 1991, transported to the laboratory, and maintained in 12 m tanks. After about 30 days acclimation, lengths and weights of all fish were measured. These measurements were repeated at 2 month intervals,for 14 months in the first group and 10 months in the second. The mean weights reached at the end of these periods were 462 g and 383 s. respectively. Fish were fed with laboratory prepared moist food. and the amount eaten daily was controlled. Survival rate at the end of the experiment was 90.5% in group B-1 and95.5% in group B-2. Temperature, measured daily, ranged from 12ºC to 20°C. This paper provides information on the capture, transport, acclimation and maintenance of the fish throughout the experiment.Versión del editor0,000

Lasting temperature effects on the muscle tissue, body growth and fillet texture of adult turbots, Scophthalmus maximus, L.

In the teleosts, several factors can influence the muscle growth patterns of fish by a modulation of the hypertrophy and hyperplasia. The temperature (T) is one of the most important environmental factors. Thus, the T history of fish influences on their potential growth, as it has been observed in Salmon, Salmo salar (Johnston et al., 2003) and other species. The T imprinting can influence on the muscle cellularity throughout the advanced stages of life due to the lasting T effects on myogenic cells precursors (MPC) (Steinbacher et al., 2011). In different teleost species, a correlation between texture and muscle fibre size has been demonstrated (Hatae et al., 1990). Hence, the thermal history can also influence in the flesh texture. In the present work we study the lasting T effects in adult turbots reared at different Ts during the early phases. This species reaches ≈ 1.5 kg at 18-20 months of age and the first sexual maturity takes place at ≈ 24 month

Histología de los folículos post-ovulatorios en ovarios de Sardina pilchardus (Walb.) de la plataforma Nor-Atlántica de la Península Ibérica

Se describen los aspectos histológicos de los ovarios hidratados y tres niveles de degenaración de los folículos post-ovulatorios observados en 150 muestras histológicas de Sardina pilchardus de la plataforma Nor-Atlántica de la Península Ibérica. Se estimó la hora probable de puesta de la sardina entre las 19'00 h y las 21'00 h GMT.The histological aspects of hydrated ovaries and three levels of degeneration of follicles are described, based on the observation of 150 histologicas samples of Sardina pilchardus from the North-Atlantic continental shelf of the Iberian Peninsula. The estimated spawning time of the sardine was between 19'00 h and 21'00 h GMT.Versión del editor0,000

Coastal upwelling off the Rías Bajas, Galicia, Northwest Spain. II. Benthic studies

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Analysis of qPCR reference genes stability determination methods and a practical approach for efficiency calculation on a turbot (Scphthalmus maximus) gonad dataset

Gene expression analysis by reverse transcription quantitative PCR (qPCR) is the most widely used method for analyzing the expression of a moderate number of genes and also for the validation of microarray results. Several issues are crucial for a successful qPCR study, particularly the selection of internal reference genes for normalization and efficiency determination. There is no agreement on which method is the best to detect the most stable genes neither on how to perform efficiency determination. In this study we offer a comprehensive evaluation of the characteristics of reference gene selection methods and how to decide which one is more reliable when they show discordant outcomes. Also, we analyze the current efficiency calculation controversy. Our dataset is composed by gonad samples of turbot at different development times reared at different temperatures. Turbot (Scophthalmus maximus) is a relevant marine aquaculture European species with increasing production in the incoming years. Since females largely outgrow males, identification of genes related to sex determination, gonad development and reproductive behavior, and analysis of their expression profiles are of primary importance for turbot industryVersión del edito