Protamine-like sperm nuclear basic proteins in the primitive frogAscaphus trueiand histone reversions among more advanced frogs
✍ Scribed by Kasinsky, H.E.; Gutovich, L.; Kulak, D.; Mackay, M.; Green, D.M.; Hunt, J.; Ausio, J.
- Book ID
- 102648139
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 964 KB
- Volume
- 284
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Sperm nuclear basic proteins (SNBPs) that condense chromatin are very diverse. In animals, evolution of SNBPs has proceeded from lysine-rich histone H type in sponges to more arginine-rich protamine-like PL and protamine P types. Yet sporadic PL/P to H reversions are known to occur in both protostomes and deuterostomes. To determine why this is the case, we have examined SNBPs in eleven anuran species. We find that sperm of the primitive, internally fertilizing archeobatrachian frog A. truei (family Ascaphidae) has PL/P type (42 mol % arginine), with an electrophoretic profile similar to SNBPs in another archeobatrachian, externally fertilizing Leiopelma hochstetteri (family Leiopelmatidae). Cytochemistry of sperm nuclei in the advanced, externally fertilizing neobatrachian frogs Crinia signifera and C. deserticola (family Myobatrachidae) indicates that they have reverted to H type SNBPs. This is also known to be the case in externally fertilizing Rana (family Ranidae) and Silurana, a subgenus of Xenopus (family Pipidae). Such a trend, from PL/P type SNBPs in two archeobatrachians to sporadic reversions to H type in more advanced frogs, parallels the ultrastructural simplification from complex A. truei introsperm to