Spermatogenesis of the lizard Lacerta vivipara: histological studies and amino acid sequence of a protamine lacertine 1.

The lizard Lacerta vivipara is a seasonal breeder with a well characterized reproductive cycle. An histological study of the lizard testis has been performed at different stages of spermatogenesis and the nuclear basic proteins content was assessed by electrophoretical analysis. Two protamines, lacertines 1 and 2, are present in spermatozoa in April and May. We have isolated lacertine1 and characterized a protamine with a mass of 4,963.7 Da. Amino acid sequence of this protamine (41 residues) was established from data provided by automated Edman degradation. It is characterized by a basic amino acid stretch in the N- and C-terminal regions and by a central part which only consists of 3 different intermingled amino acids. This protamine presents 62% homology with scylliorhinine Z3 from dog-fish Scylliorhinus caniculus and 58% homology with quail protamine. The reported lizard protamine sequence is the first reptilian protamine sequence available so far.