SPERM-SPECIFIC BASIC-PROTEINS IN THE HOLOCEPHALAN FISH HYDROLAGUS-COLLIEI (CHONDRICHTHYES, CHIMAERIFORMES) AND COMPARISON WITH PROTAMINES FROM AN ELASMOBRANCH

Seven basic proteins can be isolated from sperm nuclei of the holoceph alan ratfish Hydrolagus colliei. Two of these proteins (R3 and m0) are devoid of cysteine, whereas five of them (R1, R2, m1, m2, and m3) con tain low levels of this amino acid residue. The proteins R1, R2, and R 3 are major ones in the sperm nuclei of H. colliei, and they are analo gous to basic proteins Z1, Z2, and Z3 (scylliorhinines) from the sperm of the elasmobranch Scyliorhinus canicula. However, taking into accou nt the partial sequence of R3 protein and the number of cysteines in R 1 and R2, these proteins do not seem to be homologous to the scylliorh inines. A comparison of sperm basic proteins between H. colliei (a hol ocephalan) and S. canicula (an elasmobranch) suggests a remarkable div ergence of these proteins from a common ancestral pattern during the e volution of Chondrichthyes.