Selection of non-apoptotic sperm by magnetic activated cell sorting in Senegalese sole (Solea senegalensis)

Senegalese sole (Solea senegalensis) is a promising species in aquaculture. However, due to decreased sperm quality in F1 generations and the absence of courtship in those individuals born in captivity, artificial fertilization is being used to generate new progenies. The objective of this study was to implement a sperm selection method for non-apoptotic sperm subpopulation recovery prior to sperm cryopreservation. In particular, magnetic activated cell sorting (MACS) is used to eliminate apoptotic spermatozoa. This study represents the proof-of-concept for MACS applicability in teleost species relevant in aquaculture. Apoptotic cell population was studied by flow cytometry using YO-PRO 1 and a caspase detection kit. Also, reactive oxygen species were measured in sperm samples. Our data demonstrated that caspase detection is more specific than YO-PRO 1 in the identification of apoptotic cells in S. senegalensis seminal samples. The results showed that the percentage of apoptotic cells (caspase positive) was significantly higher (p=0.04) in seminal samples from F1 than from wild individuals. MACS removed a significant number of apoptotic cells from the samples (54% and 75% in wild and F1 individuals, respectively), decreasing the level of cells positive for reactive oxygen species (p=0.17). In conclusion, this technique reduces the percentage of non-functional spermatozoa in a seminal sample prior to cryopreservation. This novel technique can be applied directly in the aquaculture industry.En prens

Evolution of egg production and parental contribution in Senegalese sole,Solea senegalensis, during four consecutive spawning seasons

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Reproductive performance of captive Senegalese sole, Solea senegalensis, according to the origin (Wild or cultured) and gender.

Aim of study: The reproductive performance over a five year period in three different sole broodstocks: wild males with cultured females (WM), cultured males with wild females (CM), and a control of cultured males and females (C). Area of study: Cantabria, Northern Spain. Material and methods: The parental contribution was evaluated through the allocation of hatched larvae and a behavioural study was performed using underwater video recordings. Main results: Fertilized natural spawns were only obtained from group WM showing a significantly higher mean annual volume of floating eggs compared with groups CM and C. Over the entire 5-yr a higher number of spawns, total and floating volumes of eggs were obtained compared with groups CM and C. The analysis of four polymorphic microsatellites enabled the identification of the individuals involved in the fertile spawns by parental assignment. The percentage of individuals contributing to spawns ranged between 56.3% and 75% showing fidelity patterns. However between 46.2% and 68.6% of the contribution to production was a result of the crossing of three single couples. According to the behaviour analysis, group WM presented the highest peak of activity at 20:00 h and a higher activity profile during the night, moreover, the courtship behaviours “swim follow” and “swim followed”, were only recorded in group WM. Research highlights: The study has importance for aquaculture as it demonstrated how broodstocks with wild males and cultured females had adequate egg production for a commercial operation to supply eggs and implement single sex breeding programs