Potential role of the acrosome of sturgeon spermatozoa in the fertilization process

Abstract

Sturgeon gametes are unique in that their spermatozoa possess acrosome containing acrosomal enzymes whereas their eggs are perforated by numerous micropyles. Thus the function of acrosome, which undergoes acrosomal reaction and filament formation, is unclear. The acrosomal reaction of sterlet Acipenser ruthenus spermatozoa was induced by sperm exposure to the solution containing Ca 2+ and high pH. The rate of affected spermatozoa was evaluated using Soybean Trypsin Inhibitor-Alexa conjugate fluorescent staining. Fertilization and hatching test using sperm of this way disrupted acrosome and non-treated sperm as a control proofed necessity of acrosome integrity for fertilization. Increasing percentage of spermatozoa with disrupted acrosome highly decreased percentage of hatching, in spite of electron microscopy verification that the spermatozoa bearing such disrupted acrosomes were able to reach the micropyle. In addition the significant positive correlation between the ability of spermatozoa to induce acrosomal reaction by activation solution and sperm fertilizing ability suggested that spermatozoa, which are able to activate the acrosomal reaction, are more successful in fertilization.

Morphology and ultrastructure of Dabry’s sturgeon ( Acipenser dabryanus ) spermatozoa using scanning and transmission electron microscopy

“…The number and sizes of PLPs vary among species, and those in A. dabryanus are quite similar with those in A. gueldenstaedtii (Table ). It was considered that the PLPs may anchor the egg in fast flowing water during spawning and fertilization (DiLauro et al, ; Psenicka et al, ; Psenicka, Rodina, & Linhart, ).…”

Ultrastructural and Morphometric Analysis of Gametes in Neotropical Teleost Fishes

“…The presence of only one such structure is common in teleost fish, and is a characteristic used to differentiate the oocytes from other species with multiple micropyles like Sturgeon (Psenicka et al, 2011;Siddique et al, 2016).…”

“…The difference in the morphology of the spermatozoa head of different species may be related to fertilization. The fact that species such as sturgeon present acrosome and subacrosome (Psenicka et al, 2008) and oocytes with many micropyles (Psenicka et al, 2011;Siddique et al, 2014), may induce polyspermy.…”

“…Most fish species have ovoid shaped eggs and a single micropyle (Ganeco and Nakaghi, 2003) or a single oocyte with several micropyles (Psenicka et al, 2011).The sperm cell is divided into head, midpiece and flagellum (Nagahama, 1983) and in a few other species, such as sturgeon, sperm cells have acrosome and subacrosome Psenicka et al, 2008). Some spermatozoids can still present at the end of the flagellum a structure similar to a keel (Alavi et al, 2009).…”

Effect of season on proteases and serine protease inhibitors of Siberian sturgeon (Acipenser baeriiBrandt, 1869) semen

“…Trypsin-like activity has been identified and characterized in spermatozoa of the sturgeon fish (Ciereszko et al, , 1996(Ciereszko et al, , 2000. This activity is similar to acrosin and is localized in the acrosome (Psenicka et al, 2008(Psenicka et al, , 2011. In higher vertebrates, acrosin is present as inactive zymogenproacrosin, and its activation involves several steps through limited proteolysis (Baba et al, 1989).…”