DEVELOPMENTAL BIOLOGY 74, 343-350 (1980) Arylsulfatase of Sea Urchin Sperm 2. Arylsulfatase as a Lysin of Sea Urchins’ MOTONORI HOSHI AND TSUNEO MORIYA Biochemical Laboratory, Institute of Low Temperature Science, Hokkaido University, Sapporo 060, Japan Received February 15, 1979; accepted in revised form June 22, 1979 An arylsulfatase is defined as a lysin of sea urchin sperm from the following evidences. (1) The activity is detected in the sperm of all the sea urchins investigated, and the activity is partially liberated from the cells after the acrosome reaction (Moriya and Hoshi, 1979a). (2) Fertilization is completely inhibited in the presence of 40 n&fp-nitrophenyl sulfate, which is an artificial substrate of arylsulfatase, but is not inhibited by p-nitrophenyl phosphate at the same concentration. (3) The inhibitory effect ofp-nitrophenyl sulfate on fertilization is remarkably diminished by pretreat- ment of eggs with arylsulfatase before insemination. (4) Sperm arylsulfatase as well as limpet arylsulfatase appear to digest the vitelline coat and jelly coat. INTRODUCTION Since Yamane (1935) observed dispersal of the egg investments by an extract of mammalian sperm, lysins have been found in such animals as mammals, reptiles, am- phibians, tunicates, hemichordates, crusta- ceans, annelids, and mollusks except for cephalopods (for a review, see Dan, 1967). In echinoderms, Isaka et al. (1966) isolated a jelly-dispersing enzyme from a homoge- nate of sea urchin sperm, but it is not known whether this enzyme is actually in- volved in the penetration of sperm through the jelly coat. Levine et al. (1978) have recently found an acrosin-like enzyme in the sperm of sea urchin, which seems to be involved in the fertilization process. The investments of sea urchin eggs, namely, the vitelline coat and jelly coat, comprise pro- tein, carbohydrate, and sulfate (Glabe and ’ This paper is dedicated to Professor Juro Ishida on the occasion of his 70th birthday. A preliminary report of this work was presented at the 8th International Congress of the International Society of Developmental Biologists at Tokyo, 1977. This work was supported in part by grants from the Ministry of Education of Japan and from the Itoh Science Foundation. Vacquier, 1977; Tayler, 1956). Fucose-4-sul- fate (Ishihara et al., 1973) and sialic acids (Isaka et al., 1970) have been reported as main sugar components of the jelly. We expected, therefore, that sulfatase, siali- dase, other glycosidases, and protease are possible candidates for the lysin(s) of sea urchins. We have recently reported that an aryl- sulfatase exists in both the spermatozoa and the seminal plasma of the sea urchins examined (Moriya and Hoshi, 1979a, b) and that about 20% of the total activity is re- leased from the spermatozoa when the sperm undergo acrosome reaction. These observations have led us to assume that arylsulfatase is the lysin, or at least one of the lysins, in sea urchins. In order to define arylsulfatase as a lysin, it is essential to examine the following points: (i) if the enzyme digests the vitelline coat and/or jelly coat; and (ii) if fertilization is blocked when the enzyme of sperm is inhibited in some way, for example, by the addition of an artificial substrate such asp-nitrophenyl sulfate. We show here that the sperm arylsulfat- ase fulfills these requirements for the lysin. 343 0012.1600/80/020343-08$02.00/0 (‘opyright 0 1980 by Academic Press. 11~ All rights of reproduction in any form reserved.