Induction of the Acrosome Reaction in Black Tiger Shrimp (Penaeus monodon) Requires Sperm Trypsin-Like Enzyme Activity1

Abstract

Trypsin-like enzymes in egg water (EW), a natural acrosome reaction (AR) inducer, are known for their importance in shrimp AR. In this report, we describe a unique phenomenon of the AR of black tiger shrimp (Penaeus monodon) sperm. It was completed within 45-60 sec and comprised only the acrosomal exocytosis and depolymerization of the sperm head anterior spike. We used peptidyl fluorogenic substrates to show the presence of trypsin-like enzymes in P. monodon EW and sperm, but minimal activities of chymotrypsin-like enzymes. In sperm, these trypsin-like enzymes existed both on the sperm surface and in the acrosome. The acrosomal enzyme was revealed as a 45-kDa band by fluorogenic substrate in-gel zymography. Although EW possessed high trypsin-like enzyme activities, they were not essential for the AR induction; EW pretreated with an irreversible trypsin inhibitor, or heat-inactivated EW (HI-EW), to abolish the trypsin-like activities could still induce the AR. The HI-EW-induced AR was inhibited by the presence of a membrane impermeant soybean trypsin inhibitor (SBTI) in the sperm suspension, indicating the significance of sperm-borne trypsin-like enzymes (on the surface and/or in the acrosome) in this AR process. However, pretreatment of sperm with SBTI followed by its removal from the suspension still allowed the AR to occur within 5 min of sperm exposure to HI-EW. Since trypsin-like activity of the SBTI-pretreated sperm surface at 5 min after SBTI removal was at the minimal level, our results suggest the importance of the acrosomal trypsin-like enzyme in the AR process.

The male reproductive system of Hippolyte inermis Leach 1815 (Decapoda, Caridea)

“…In our study, the spermatozoa exhibit the shape of a small umbrella due to the development of a long spike. The function of this spike seems to be involved in the fertilization of ovocites (Lynn and Clark 1983;Demestre et al 1997;Kruevaisayawan et al 2008).…”

N‐linked mannose glycoconjugates on shrimp thrombospondin, pmTSP‐II, and their involvement in the sperm acrosome reaction

“…As already mentioned, the most well‐recognized glycoconjugate studies in invertebrates are the reports on echinoderms in which the glycopolymer in their egg jelly was identified as a fucose‐sulfate polymer (Alves, Mulloy, Moy, Vacquier, & Mourao, ; Mulloy, Ribeiro, Alves, Vieira, & Mourao, ; Vilela‐Silva et al, ) that was shown to possess primary physiological functions in species‐specific gamete interactions and in modulating the AR response (Alves, Mulloy, Diniz, & Mourao, ; Vacquier & Moy, ; Vilela‐Silva, Castro, Valente, Biermann, & Mourao, ). The existence and function of sulfated glycoproteins has been shown in many other invertebrate and vertebrates species (Pomin, ; Sylvester, Morales, Oko, & Griswold, ), but not in some marine shrimp and abalone (Kruevaisayawan et al, ; Kruevaisayawan et al, ). This discrepancy could simply reflect the nature of species’ differences in their glycosylation patterns.…”

Inhibitory effect of a reproductive‐related serpin on sperm trypsin‐like activity implicates its role in sperm maturation of Penaeus monodon

“…Murine SERPINE2 is an important factor synthesized in the seminal vesicle and secreted into seminal fluid, which functions as a sperm decapacitation factor that binds with sperm and inhibits proteolytic activity until final maturation and capacitation in the oviduct (Lu et al, ). In P. monodon , successful induction of the sperm acrosome reaction required trypsin‐like protease activity (Kruevaisayawan et al, ). Sperm treated with protease inhibitors showed a decreased ability to undergo the acrosome reaction, while the acquisition of sperm trypsin‐like protease activity indicated the complete maturation of sperm for fertilization.…”