On the diversity of sperm basic proteins in the vertebrates: VI. Cytochemical and biochemical analysis in birds

Abstract

AbstractBy cytochemical criteria, the sperm basic proteins in birds are remarkably constant. Type 1 protamines are found in five species of birds representing four orders: Coturnix japonica (quail) and Gallus domesticus (rooster), order Galliformes; Anas platyrhynchos (duck), order Anseri‐formes; Melopsittacus undulatus (budgerigar), order Psittaciformes; Molothrus ater (cowbird), order Passeriformes. This constancy is confirmed by the isolation of electrophoretically typical protamines from sperm nuclei of quail, duck and budgerigar as well as from Carduelis carduelis (goldfinch), another passeriform bird, and Columba livia (pigeon), order Columbiformes. In each species only typical protamines are found in ripe spermatozoa; no histones are present. In quail and pigeon, several protamines of similar molecular weight can be found, whereas in duck, goldfinch, and budgerigar a single protamine component is apparent. An additional basic protein is found in budgerigar, which does not appear to be part of the ripe sperm nucleus. Such additional basic proteins have not been detected in the other species studied. No significant amounts of intermediate proteins that could be involved in spermatid maturation have been detected either cytochemically or biochemically in any of the species studied. The overall similarity amongst protamines from seven birds representing five orders might be related to the uniform mode of reproduction within the class Aves, consisting of internal fertilization and egg laying.