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The aim of this study was to address an analysis of spatial distribution, reproduction, population parameters and secondary production of the natural beds of the well-defined morphotypes of the clam Mactra stultorum (brownish and whitish variants) along the SW Spanish coast. The main findings showed that the presence and the frequencies of both morphotypes increased near the estuaries of rivers, particularly the Guadalquivir River. However, subtle differences in habitat preferences have been revealed and the brownish variant showed a wider and deeper distribution. High similarity in the gonadal development was recorded for both variants. It started in January, continued into late winter and early spring and ended with a spawning period from April to August. An energy storage-utilization cycle, coupled to the reproductive and resting periods and driven by sea water temperature variations and food availability, was also observed. The abovementioned period of gamete emissions resulted in a recruitment pattern with a one-time settlement period per year. Von Bertalanffy growth functions provided an asymptotic length of 46.7 mm (whitish) and 50 mm (brownish) and growth constants of 0.55 (whitish) and 0.50 yr−1 (brownish). The mean annual biomass (B ̅) ranged between 0.062 (whitish) and 0.076 g AFDW m−2 yr−1 (brownish) (AFDW: ash-free dry mass). Individual somatic production showed the highest value at 32 and 34 mm shell length, and annual production (P) ranged between 0.075 and 0.113 g AFDW m−2 yr−1, resulting in renewal rate (P/B ̅) values between 1.21 and 1.37, for the whitish and brownish variants, respectively. These results provide basic knowledge about the reproduction and population dynamics of this species along the Atlantic coast, particularly in the sandflats near the estuary of the Guadalquivir River. They could also shed additional light upon taxonomic differentiation and clarify the ecological role of both variants when compared with two bivalve sympatric spec

Phospholipids (PL) are essential molecules for larval growth and development. In this study, growth, lipid metabolism and gene expression responses associated with different dietary PL levels in pelagic sole larvae were evaluated. In a first trial, the long-term effects on growth and survival of two experimental microdiets (MD) containing high (High-PL) or low (Low-PL) PL levels were tested and compared to a diet based on live prey (rotifers). The MD were supplied from 3 to 10 days post-hatch (dph) and Artemia from day 8 to 29 dph. High-PL fed larvae had higher dry mass (1.2-fold) than LowPL fed larvae at 8 dph and both MD were smaller (2.9-fold) than larvae fed live preys. However, a compensatory growth (33% between 8 and 20 dph) occurred when MD were substituted by Artemia and by the end of the trial no significant differences in mass or survival occurred between the dietary treatments. In a second trial, growth, lipid metabolism and gene expression profiles of larvae fed with MD up to 8 dph were analyzed. Growth data confirmed that mass of larvae fed with High-PL was higher (1.3-fold) than the those fed Low-PL and they had lower levels of triacylglycerol (2.8- fold), cholesterol (1.2-fold) and cetoleic acid (1.7-fold). Histological analysis indicated an excess of lipid vacuoles in larvae fed with Low-PL and the expression analysis revealed a coordinated response to enhance lipid mobilization since the expression of genes involved in PL intermediate synthesis, PL remodeling as well as eight apolipoprotein was up-regulated. The down-regulation of apolipoprotein apob2 in larvae fed with LowPL indicated a specific regulation by PL levels. The present work provides insight into the responses associated with dietary PL in early fish larvae, which will be of use for future studies aimed as designing effective larval sole diets.

The aim of this study was to evaluate the short- and long-term effects of diets consisting in rotifers enriched with different oil emulsions (differing mainly in triacylglycerols levels) and provided during the first week of life. Survival, growth, metamorphosis progress, lipid profile and molecular regulatory pathways were evaluated. For comparison purposes, a diet used routinely in the aquaculture industry based on microalgae was also carried out. The present study shows that dietary triacylglycerols (TAG) levels and fatty acid composition modulate larval survival and growth when supplied during larval pelagic stages. Histological observation and gene expression pattern showed that early larvae regulated intestinal lipid transport, showing a coordinate activation of apolipoproteins transcripts. Multivariate analyses identified the major contribution of apoEa to discriminate samples by dietary treatments, pointing out the importance of this apolipoprotein as key molecular marker for intestinal lipid mobilization. However, our data indicate that transport capacity is limited in early larvae, increasing in anterior intestine as intestine maturates with larval development, while the increase of fat deposits in the posterior intestine in older larvae supports the limited capacity of this gut section for lipid transport. The accumulation of TAG, phosphocholine (PC) and oleic acid (OA) along pre- and early metamorphosis indicates that these lipids influences positively daily mortality rate, eye-migration progress and growth. Moreover, larval TAG amounts correlate highly with apoA-IVBa3 mRNA levels, indicating an active role of this apolipoprotein in endogenous lipid mobilization during development. These data provide new evidence that TAG, PC and OA dietary levels are important for larval development and complement the available information about energy management in sole larvae reinforcing the rotifer feeding period as critical to produce high-quality larvae. Statement

The apolipoprotein A-I (ApoA-I) is an essential component of the high density lipoproteins (HDL). In this study, the cDNA and genomic sequences of this apolipoprotein were characterized for first time in Solea senegalensis. The predicted polypeptide revealed conserved structural features including ten repeats in the lipid-binding domain and some residues involved in cholesterol interaction and binding. The gene structure analysis identified four exons and three introns. Moreover, the synteny analysis revealed that apoA-I did not localize with other apolipoproteins indicating a divergent evolution with respect to the apoA-IV and apoE cluster. The phylogenetic analyses identified two distinct apoA-I paralogs in Ostariophysi (referred to as Ia and Ib) and only one (Ib) in Acanthopterygii. Whole-mount in situ hybridization located the apoA-I signal mainly in the yolk syncytial layer in lecitotrophic larval stages. Later at mouth opening, the mRNA signals were detected mainly in liver and intestine compatible with its role in the HDL formation. Moreover, a clear signal was detected in some regions of the brain, retina and neural cord suggesting a role in local regulation of cholesterol homeostasis. After metamorphosis, apoA-I was also detected in other tissues such as gills, head kidney and spleen suggesting a putative role in immunity. Expression analyses in larvae fed two diets with different triacylglycerol levels indicated that apoA-I mRNA levels were more associated to larval size and development than dietary lipid levels. Finally, qPCR analyses of immature and mature transcripts revealed distinct expression profiles suggesting a posttranscriptional regulatory mechanism.

The apolipoprotein A-IV (ApoA-IV) plays a key role in lipid transport and feed intake regulation. In this work, four cDNA sequences encoding ApoA-IV paralogs were identified. Sequence analysis revealed conserved structural features including the common 33-codon block and nine repeated motifs. Gene structure analysis identified four exons and three introns except for apoA-IVAa1 (with only 3 exons). Synteny analysis showed that the four paralogs were structured into two clusters (cluster A containing apoA-IVAa1 and apoA-IVAa2 and cluster B with apoA-IVBa3 and apoA-IVBa4) linked to an apolipoprotein E. Phylogenetic analysis clearly separated the paralogs according to their cluster organization as well as revealed four subclades highly conserved in Acanthopterygii. Whole-mount analyses (WISH) in early larvae (0 and 1 day post-hatch (dph)) showed that the four paralogs were mainly expressed in yolk syncytial layer surrounding the oil globules. Later, at 3 and 5 dph, the four paralogs were mainly expressed in liver and intestine although with differences in their relative abundance and temporal expression patterns. Diet supply triggered the intensity of WISH signals in the intestine of the four paralogs. Quantification of mRNA abundance by qPCR using whole larvae only detected the induction by diet at 5 dph. Moreover, transcript levels increased progressively with age except for apoA-IVAa2, which appeared as a low-expressed isoform. Expression analysis in juvenile tissues confirmed that the four paralogs were mainly expressed in liver and intestine and secondary in other tissues. The role of these ApoA-IV genes in lipid transport and the possible role of apoA-IVAa2 as a regulatory form are discussed.

The aim of the present study was to evaluate the culture potential of meagre, Argyrosomus regius (Asso, 1801). Trials were conducted in two different facilities in Spain, the LIMIA research centre (Mallorca) and the IFAPA research centre “El Toruño” (El Puerto de Santa Maria). In May 2006, males with free milt and females with vitellogenic oocytes bigger than 500 μm were injected with salmon gonadotropin releasing hormone analogues (sGnRHa). Spawning occurred approximately 38 hours after induction. Fecundity was high with 1.207.000 eggs collected from a 13 kg female at LIMIA in a single spawn. The larval development, growth and morphological changes were described from 0 to 30 days post hatching (DPH). The mean length of the newly hatched larvae ranged from 2.20 ± 0.02 mm (LIMIA) to 3.19 ±0.09 mm (IFAPA). Feeding began on 3 DPH, initial swim bladder inflation was observed on 5 DPH, and metamorphosis was completed on 30 DPH. Growth was very fast and the post-larvae reached 15.11 ± 3.49 mm (LIMIA) and 11.66 ± 0.96 mm (IFAPA) in 30 days Cannibalism was observed from 15 DPH onwards. These preliminary results indicate the meagre as a priority species for the diversification in aquaculture., L'objectiu de l’estudi va ser avaluar el potencial del cultiu de la corbina, Argyrosomus regius (Asso, 1801). Les experiències es van realitzar en dues diferents instal·lacions a Espanya. El centre d'investigacions LIMIA (Mallorca) i el centre d'investigacions IFAPA "El Toruño" (El Port de Santa Maria). Al maig del 2006, mascles fluents i femelles amb ovòcits vitel·logènics majors de 500 micres van ser injectats amb anàlegs de l'hormona alliberadora de gonadotropina del salmó (sGnRHa). La posta es va obtenir aproximadament 38 hores després de la inducció. La fecunditat va ser alta, obtenintne 1.207.000 ous recollits d'una sola femella de 13 kg en una única posta. El desenvolupament larvari, creixement i canvis morfològics es van descriure des del dia 0 al 30 després de l'eclosió (DPH). La longitud mitjana de les larves recent eclosionades va variar entre 2.20 ± 0.02 mm (LIMIA) i 3.19 ± 0.09 mm (IFAPA). L'alimentació va començar el 3 DPH, la inflació inicial de la bufeta natatòria es va observar el 5 DPH, i la metamorfosi es va completar el 30 DPH. El creixement va ser molt ràpid aconseguint les post larves 15.11 ± 3.49 mm (LIMIA) i 11.66 ± 0.96 mm (IFAPA) en 30 dies. A partir del 15 DPH es va observar canibalisme. Aquestes dades, assenyalen a la corbina com una espècie prioritària en la diversificació de l'aqüicultura.

The gametogenic cycle of three populations of Chamelea gallina (L., 1758) from the Andalusian coast (southern Spain) was determined by means of histological methods and variations in dry weight. The pattern shown was very similar in all of them. In Atlantic populations (Punta Umbría and Doñana), spawning occured between January and September, and a short period of sexual repose took place from the end of September until November, when gametogenesis began. In the Mediterranean population (Fuengirola), spawning lasted almost the entire year, even though in autumn and winter spawning percentage was lower than in spring and summer. The size at sexual maturity was established as 16 mm., Se ha establecido el ciclo gametogénico de tres poblaciones de Chamelea gallina (L., 1758) del litoral andaluz, utilizando métodos histológicos e índices de condición. El patrón fue bastante similar en las tres poblaciones. En las suratlánticas (Punta Umbría y Doñana) se observó un amplio periodo de emisión que abarcó desde enero hasta septiembre y un corto periodo de reposo sexual desde finales de septiembre hasta noviembre, a partir del cual comenzó la gametogénesis. En la población surmediterránea (Fuengirola) el periodo de emisión abarcó casi la totalidad del año, si bien en los meses más fríos (otoño e invierno) el porcentaje de ejemplares en puesta fue más bajo que en los meses cálidos (primavera y verano). La talla de madurez sexual se ha establecido en 16 mm.

We present a histomorphological description of the digestive tract of the oyster Crassostrea angulata (Lamarck, 1819), as well as a histochemical study of its carbohydrate distribution. The study shows that, in general, glycogen is found in the connective tissue, and neutral mucopolysaccharides/glycoproteins and/or acid mucosubstances in the epithelium and basal cell layers. Glycogen was not detected in the digestive gland, possibly because of its mobilization to the connective tissue for reproduction., Se realiza una descripción histomorfológica del aparato digestivo del ostión Crassostrea angulata (Lamarck, 1819) y se pone de manifiesto la distribución de carbohidratos mediante técnicas histoquímicas. La pauta general observada es la presencia de glucógeno en el tejido conjuntivo y de mucopolisacáridos/glicoproteínas neutras y/o ácidas en las membranas basales y el epitelio. En la glándula digestiva no se observa glucógeno debido, posiblemente, a su movilización hacia el tejido conjuntivo para su posterior uso con fines reproductivos.