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

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 degrees 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 BC, 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.