Identification of an amphibian oocyte nuclear protein as a candidate for a role in embryonic DNA replication

S. Bucci, M. Ragghianti, I. Nardi, M. Bellini, G. Mancino, J. C. Lacroix

Research output: Contribution to journalArticlepeer-review


Monoclonal antibodyB(24/3) recognizes a nuclear protein of 104 kD in germinal vesicles of newt oocytes. Immunohistostaining of oocytes at different stages of growth shows an accumulation of B24 protein throughout oogenesis. During developmentd B24 protein is located inside embryonic cell nuclei from the onset of cleavage onwards. It gradually decreases from gastrulation and disappears at the tailbud stage. The NvB24 17.1clone was isolated from an ovary expression library of the newt Notophthalmus viridescens and then sequenced: the open reading frame is capable of encoding a polypeptide of 744 amino acids. Northern blot experiments have shown that the 17.1 clone recognizes a single transcript of about 3 Kb in the ovary. In situ hybridization experiments showed that B24 mRNA transcription starts from previtellogenic oocytes, and is followed by the appearance and gradual accumulation of B24 protien in germinal vesicles of medium and large size oocytes. Keeping in mind the sequence similarity shown by the B24 protien to the mouse P1 protein as well as to the budding yeast Mcm3 and fission yeast cdc21 proteins, B24 protein can be speculated to play a role in the events of DNA replication during early amphibian embryogenesis. As B24 antigen is located in the sphere organelles both inserted on the lampbrush chromosomes and free in the oocyte nucleoplasm, an additional possible role of B24 protein could be related to assembling and/or storing snRNPs during oogenesis.

Original languageEnglish (US)
Pages (from-to)509-517
Number of pages9
JournalInternational Journal of Developmental Biology
Issue number4
StatePublished - 1993
Externally publishedYes


  • Embryogenesis
  • Gene expression
  • Immunofluorescence
  • In situ hybridization
  • Oogenesis

ASJC Scopus subject areas

  • Embryology
  • Developmental Biology


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