Yvon Normant

Cryopreservation of turbot (Scophthalmus maximus) spermatozoa.

The aim of this study was to develop a method for cryopreserving turbot semen and to compare sperm motility characteristics, metabolic status and fertilization capacity of frozenthawed and fresh semen. The best results were obtained when spermatozoa were diluted at a 1:2 ratio with a modified Mounib extender, supplemented with 10% BSA and 10% DMSO. For freezing sperm samples, straws were placed at 6.5 cm above the surface of liquid nitrogen (LN) and plunged in LN. The straws were thawed in water bath at 30 degrees C for 5 sec. Use of this simple method resulted in a 60 to 80% reactivation rate of the thawed spermatozoa. Although the percentage of motile spermatozoa in the frozen-thawed semen samples was significantly lower than in fresh semen, spermatozoa velocity and respiratory rate remained unchanged. The process of cryopreservation significantly decreased intracellular ATP content. The fertilization rate of frozen-thawed spermatozoa was significantly lower than that of fresh spermatozoa, but it increased with sperm concentration.

Artificial insemination in turbot (Scophthalmus maximus): determination of the optimal sperm to egg ratio and time of gamete contact

Abstract In high-quality batches of eggs (mean egg viability rate 89.6%), fertilization success (FS = number of 4-cell-stage eggs/number of viable eggs) was maximal when the ratio of spermatozoa to egg was above 6 × 10 3 . For lower ratios, FS decreased and became highly variable. In lower-quality batches of eggs (mean egg viability rates 72.0 and 75.9%), FS was variable even for the highest sperm to egg ratios. For the ratio of 1.5 × 10 3 spermatozoa per egg, the occurrence of maximum FS in relation to increasing contact time between gametes was scattered and mainly recorded after 2 and 3 min. For the ratio of 6 × 10 3 spermatozoa per egg, maximum FS was mainly observed after a contact of 1 min between gametes. In commercial production, a minimum ratio of 6 × 10 3 spermatozoa per egg and a contact time between gametes of 3 min is recommended for the artificial insemination of turbot eggs.

Reliable assessment of overripening in turbot (Scophthalmus maximus) by a simple pH measurement

Abstract The pH of ovarian fluid was around 8.1 in turbot spawn collected by stripping shortly after ovulation. It decreased down to 7.1 when overripening developed. A highly significant correlation ( r =0.92, P

Long-term effects of the cryopreservation of turbot (Psetta maxima) spermatozoa

The survival of turbot eggs and the rearing capacities of larvae stemmed from artificial fertilization practices using frozen-thawed spermatozoa were evaluated. Furthermore, the viability of sperm samples stored during a 9 month period in liquid nitrogen was assessed. No significant difference in the fertilization rate, hatching rate, survival and wet weight of 10-day old larvae were observed using fresh or frozen-thawed spermatozoa. The motility recorded at 10 s and 60 s post-activation and the fertilization capacity of frozen-thawed spermatozoa were not significantly decreased during a 9 month storage period in liquid nitrogen. These results confirm the high quality of the turbot spermatozoa stemmed from the cryopreservation process, allowing their use for routine aquaculture practices.

Effect of temperature, volume of ova batches, and addition of a diluent, an antibiotic, oxygen and a protein inhibitor on short-term storage capacities of turbot, Psetta maxima, ova

The effect of different parameters on short-term storage capacity of turbot ova was assessed over a 45-h period after ova collection for fertilization rates and over a 9-h period after ova collection for hatching rates. Increasing the volume of ova sampling from 0.5 to 2.5 mL, as weil as adding an antibiotic-antimicotic solution or oxygen did not significantly change the storage capacity of ova. Regarding the hatching rates, a higher storage ability was recorded at 8 and 13 oC, compared to 3 oc. The mean composition of the ovarian fluid was determined (n = 57 spawns). Use of a diluent mimicking the ovarian fluid significantly decreased the storage ability as assessed by the fertilization rates but did not modify the hatching rates. Diluting ova in an artificial ovarian fluid deprived of calcium significantly decreased the fertilization and hatching rates during the storage period. Furthermore, addition or not of soybean trypsin inhibitor (Sigma T 9003) to the artificial ovarian fluid deprived of calcium did not significantly change the results. Storage capacity of control batches of ova was low: at 13 oC, without any diluent and when ova were fertilized 3 h after stripping, the hatching rate was lowered to 62.4 ± 29.4 % (mean ± SD) of the initial value.