Evaluating the impact of moulting and chilled storage of spermatophores on the integrity of plasma membrane, acrosome and DNA of black tiger prawn ( Penaeus monodon ) spermatozoa

Abstract

To explore the impact of moulting and short-term chilled storage of spermatophores on the sperm quality for a commercially important penaeid prawn, spermatozoa of Penaeus monodon from early (B-C), middle (D0-1) and late (D2-3) moult stages were compared for sperm quality parameters relating to the structural integrity of plasma membrane (Viab%), acrosome (AR%) and DNA (SDF%) after being stored at 4°C for 0–26 days. The three different sperm extenders used for chilled storage included artificial lobster haemolymph (AH), calcium free saline (CS) and filtered seawater (FS); two storage conditions were applied either as a free sperm suspension or retained within the intact spermatophore. Results showed that (a) the lowest natural AR% was shown for B-C spermatozoa in CS whereas the highest levels were for B-C, D0-1 and D2-3 spermatozoa in FS and D2-3 spermatozoa in AH; (b) the calcium ionophore A23187 agent used in this study was able to increase the mean AR% by 6.22%; (c) the Viab% was significantly lower in CS than that in FS; (d) the SDF% significantly increased over the period of chilled storage for B-C and D0-1 spermatozoa, while the SDF% of D2-3 spermatozoa was initially elevated and did not change significantly over time; and (e) there was no difference in sperm quality between two storage conditions. This study has successfully demonstrated the moult-related variance in the percentages of acrosome-reacted and DNA-damaged spermatozoa, providing evidence of moult-related spermatophore renewal cycle in this species.