CYTOCHEMISTRY AND POLARIZATION MICROSCOPY OF AMPHIBIAN SPERM CELL-NUCLEI PRESUMED TO DIFFER IN BASIC-PROTEIN COMPOSITION

The pattern of availability of free DNA phosphates, and the kind of DN A-protein complex arrangement, both induced by nuclear basic proteins, and the richness in arginine residues in these proteins were investig ated cytochemically and cytophysically in spermatozoa of the South-Ame rican Hylidae species, Hyla fuscovaria and Hyla biobeba. The aim was t o demonstrate differences at the level of sperm histones in two specie s of Hyla until recently considered to be congeneric. The results indi cated differences in the spermatozoal nuclear basic proteins and DNA-p rotein complexes when the two species were compared. The spermatozoa o f Hyla biobeba were assumed to be likely to contain a Bloch's ''type 3 '' protein type (intermediate sperm basic protein), similarly to Hyla species of North and Central America. On the other hand, the data obta ined for the spermatozoa of Hyla fuscovaria indicated that they contai n a protamine or protamine-like protein, differing from Hyla biobeba a nd Hyla species of North and Central America. It is suggested that the differences reported here may be genus-specific, since Hyla fuscovari a has recently been reclassified as Scinax fuscovaria based on paramet ers other than sperm histone types. These findings are in agreement wi th the general view of a wide variability in sperm nuclear proteins in the Anura group.