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This study aimed to determine the maximum time of emersion of Senegalese sole ( Solea senegalensis) specimens to form the basis for a dry sole transport procedure. For this purpose, 56 specimens (922.33 ± 29.52 g body weight) were individually placed in polystyrene boxes on a wet cloth, maintaining constant temperature (15°C) during emersion trial. Specimens ( n = 7 per group) were sampled for plasma, and mortality was monitored at different points (0, 2, 6, 12, 20, 28, 36 and 44 h of emersion), and several stress (cortisol, glucose and lactate) and metabolic (triglycerides, proteins and amino acids) parameters were assessed. After sampling, each experimental group was placed in recovery tanks for the assessment of delayed mortality and feeding performance after emersion trial. Transport periods longer than 28 h produced high stress level indicated by (i) significant increase in circulating cortisol and lactate and (ii) glucose reserves mobilization. These alterations originated physiological problems during the emersion trial that induced mortality as well as problems for recovering correct feeding performance of specimens. These results suggested that at 15°C for S. senegalensis specimens (around 900 g body weight), a waterless transport is possible without direct or delayed mortality up to 28 h. [ABSTRACT FROM AUTHOR]

The article focuses on a study related to disinfection of Senegalese sole egg with iodine to minimizes the bacterial load without affecting the hatching rate and larval survival. Topics discussed include advantage of disinfection in prevention of disease transmission, evaluation of the disinfectant capacity and hatching rate in culture conditions, analysis of data normality and homogeneity of variance by the Kolmogorov-Smirnov and Levene methods, and importance of the egg developmental stage.

Melatonin actions are mediated through G protein-coupled transmembrane receptors. Recently, mt1, mt2, and mel1c melatonin receptors were cloned in the Senegalese sole. Here, their day-night and developmental expressions were analyzed by quantitative PCR. These results revealed distinct expression patterns of each receptor through development. mel1c transcripts were more abundant in unfertilized ovulated oocytes and declined during embryonic development. mt1 and mt2 expression was higher at the earliest stages (2-6 days post-fertilization), decreasing before (mt2) or during (mt1) metamorphosis. Only mt1 and mel1c expression exhibited day-night variations, with higher nocturnal mRNA levels. These results suggest different roles and transcriptional regulation of these melatonin receptors during flatfish development and metamorphosis. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to evaluate the total egg production of three groups of wild Solea senegalensis that were adapted to captivity (B1, B2 and B3) and to evaluate parental contribution through the allocation of larvae hatched over four spawning seasons (2007–2010). Total production, daily relative fecundity, and fertilisation and hatching rates were obtained. In addition, an analysis of egg diameter was performed. The total production resulted in 633 spawns and showed a number of differences in the floating volume rate and the hatching rate between each year. The mean relative fecundity and the fertilisation rate showed interannual stability. Significant differences in production were found between the different breeding tanks. The change in the egg diameter decreased as the breeding season progressed, and the relationship between egg diameter and time, calculated using the spawns of two females, showed a significant correlation (ρ=−0.426, p=0.000 and ρ=−0.362, p=0.000, respectively) and a significant fit to a cubic regression model (R2 =33.6, p=0.000 and R2 =54.3, p=0.000, respectively). Parentage analysis with four highly polymorphic microsatellites enabled the identification of the parents involved in each spawn, the relationships between males and females over the breeding season and between breeding seasons, and the reproductive rhythms of individual females. The percentage of individuals that participated in the spawns in each tank ranged between 8.7% (B1, 2009) and 51.7% (B3, 2008) annually. Paternity inference of progenies (n=3630 larvae) showed a high fidelity behaviour in Senegalese sole, with offspring allocated to the same couples throughout the breeding season (87–98%) and even between mating seasons in different years. The period of reproductive activity of the 4 most active females lasted from 96days (female 37, 2010) to 252days (female 35, 2009), with intervals between consecutive spawns ranging between 1 and 56days. [Copyright &y& Elsevier]

Abstract: The Senegalese sole (Solea senegalensis) is a flatfish that exhibits severe reproductive dysfunctions in captivity. This study aimed at investigating the existence of a dopamine (DA) inhibitory tone on the reproductive axis of this species. Four groups of Senegalese sole breeders were treated with, saline (controls, CNT), the DA antagonist pimozide (PIM, 5mg kg−1), gonadotropin-releasing hormone agonist (GnRHa, 40μg kg−1) or a combination of PIM + GnRHa (COMB). Effects were evaluated on pituitary GnRH levels (ELISA), pituitary gonadotropin subunit transcript levels (qPCR), plasma levels of sex steroids and vitellogenin (ELISA), gonad development (histology), spermiation and egg production. The GnRHa treatment induced egg release and stimulated testis maturation. In males, PIM did not affect pituitary GnRH content, but enhanced GnRHa-induced pituitary GPα transcripts and modified plasma androgen levels; moreover, PIM stimulated spermatogenesis and milt production, both alone and combined with GnRHa. In females, PIM did not affect pituitary and plasma endocrine parameters and did not affect egg production and fertilization success of the broodstock, either alone or in the combined treatment. In conclusion, data indicated the existence of a DA inhibition in mature males, which would be absent or weakly expressed in females. [Copyright &y& Elsevier]

The aim of this study was to evaluate the effect of long term natural feeding in the subsequent reproductive status of 4 years old cultured Solea senegalensis , and to determine if the potential changes were structural or feeding dependent. To this aim, two different feeding regimes were used from one year after weaning and during the following 3 years; 1) a commercial dry food diet and 2) a natural feeding regime. After this period, the proportion of fluent males and the evolution of maturity stages of females over a breeding season were studied. A complete sperm quality analysis assessment was carried out, including individual volumes, motility, density and curvilinear, rectilinear and mean velocities of spermatozoa. Moreover, viability and apoptosis indexes were analyzed as indicator of molecular sperm membrane integrity. Additionally, a morphological characterization of the testes during the spawning season was conducted. Finally, both groups were fed with the same commercial pellets during one year to evaluate the effect of the diet of previous years on sperm quality. The results of this study showed how feeding can improve not only sperm quality and quantity, but also the proportion of fluent males and females in advanced maturity stages. All the sperm quality parameters resulted significantly higher in the group fed with a natural diet. Moreover, the number of apoptotic cells was significantly higher in the group fed with a commercial diet. According to the morphological features of the testes, the animals fed with a natural diet presented more basal position, less protuberances and irregular edges when compared with the animals fed with commercial diet. Interestingly, the progression of the spermatogenesis determined by the proportion of germ cells and the production of spermatozoa determined by the wider of the ducts system was also significantly larger in the natural diet group. After the standardization of the diets, mean volume per male and production of total motile cells were significantly higher in the group that was previously fed a natural diet, confirming structural improvements. • Long term natural feeding regime improves reproductive performance in Solea senegalensis. • A long term natural feeding regime produces structural improvements in Solea senegalensis testis. • A long term natural feeding regime enhances sperm quantity and quality. • A long term natural feeding regime increases the number of mature females. [ABSTRACT FROM AUTHOR]