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Saperas, N., M. Chiva, E. Ribes, H.E. Kasinsky, E. Rosenberg, J.H. Youson, and J. Ausio, 1994. Chromosomal Proteins of the Sperm of a Cephalochordate (Branchiostoma floridae) and an Agnathan (Petromyzon marinus): Compositional Variability of the Nuclear Sperm Proteins of Deuterostomes. University of Victoria Reprinted from Biological Bulletin (1994) 186: 101-114 Chromosomal Proteins of the Sperm of a Cephalochordate (Branchiostoma floridae) and an Agnathan (Petromyzon marinus): Compositional Variability of the Nuclear Sperm Proteins of DeuterostomesAbstract. We have isolated and characterized for the first time the chromosomal proteins from the nucleus of the sperm of a lancelet (amphioxus) Branchiostoma floridae (Hubbs, 1922) (Phylum Chordata: Subphylum Cephalochordata) and of a lamprey Petromyzon marinus (Linnaeus, 1758) (Phylum Chordata: Subphylum Vertebrata: Class Agnatha). In the first case, the major protein component of the sperm-chromatin of a lancelet is a highly specialized protamine-like (PL) protein that has structural and compositional features similar to those of PL-III from bivalve mollusks. In contrast, the chromatin of the sperm of the lamprey has a structural arrangement and protein composition (histones) very similar to that found in the somatic cells of all eukartyotic organisms. Among the deuterostomes, chromosomal protein variability is considerably greater in representatives of the Phylum Chordata than in echinoderms. The possible evolutionary significance of these findings is discussed. Entire Paper |