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DNA topoisomerase II distribution in mouse preimplantation embryos
Author(s) -
St. Pierre Jason,
Wright David J.,
Rowe Thomas C.,
Wright Shirley J.
Publication year - 2002
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.10016
Subject(s) - biology , microbiology and biotechnology , premature chromosome condensation , chromatin , oocyte , embryo , gene isoform , metaphase , chromosome , genetics , dna , gene
DNA topoisomerase II (topo II) is an essential enzyme that mediates a variety of chromosome activities including DNA replication, transcription, recombination, and chromosome condensation and segregation. Isoform‐specific anti‐topo II antibodies were used to determine the distribution of topo II α and β in mouse gametes and embryos. Immunoblot analysis with two anti‐topo IIα antibodies revealed that a 170 kDa topo IIα band was present in ovary and testis. Mature sperm exhibited an 89 kDa band only, which may be a degradation product of topo IIα. Immunoblots probed with a monoclonal antibody that recognizes both isoforms, showed bands at 170 and 180 kDa, which correspond to topo IIα and β, respectively. An additional 100 kDa band was also present in ovary and testis. Mature sperm did not exhibit staining with this antibody. We also localized topo II in mouse gametes and embryos up to the blastocyst stage using immunofluorescence microscopy. While both isoforms were found in nuclei and nucleoli of germinal vesicle oocytes, topo IIα localized to metaphase chromosomes during meiosis, and only to nucleoli during embryonic interphase. Topo IIβ was absent from chromosomes of metaphase II oocytes, but localized to embryonic interphase nuclei. Both full‐length isoforms were absent from sperm, indicating topo II is stored maternally. These results identify topo II as an important component of mouse oocyte and embryonic chromatin, and suggest its involvement in oocyte maturation and preimplantation embryonic development. The different immunofluorescent staining patterns indicate topo IIα and β may serve different roles during the embryonic cell cycle. Mol. Reprod. Dev. 61: 335–346, 2002. © 2002 Wiley‐Liss, Inc.