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pEg7, a new Xenopus protein required for mitotic chromosome condensation in egg extracts.

Cubizolles F, Legagneux V, Le Guellec R, Chartrain I, Uzbekov R, Ford C, Le Guellec K - J. Cell Biol. (1998)

Bottom Line: This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation.A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts.Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

View Article: PubMed Central - PubMed

Affiliation: Biologie et Génétique du Développement, CNRS UPR 41, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France.

ABSTRACT
We have isolated a cDNA, Eg7, corresponding to a Xenopus maternal mRNA, which is polyadenylated in mature oocytes and deadenylated in early embryos. This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation. The tissue and cell expression pattern of pEg7 indicates that this protein is only readily detected in cultured cells and germ cells. Immunolocalization in Xenopus cultured cells indicates that pEg7 concentrates onto chromosomes during mitosis. A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts. Incubating these extracts with antibodies directed against two distinct parts of pEg7 provokes a strong inhibition of the condensation and resolution of mitotic chromosomes. Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

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Immunolocalization of  pEg7 in Xenopus Xl2 culture  cells. The cells were observed in  phase contrast (A, D, G, J, M, P,  S), and DNA was stained with  DAPI (B, E, H, K, N, Q, T).  pEg7 was detected by indirect  immunofluorescence using purified anti–pEg7 G antibodies (C,  F, I, L, O, R, U). (S) Arrow indicates the midbody. Bar, 10 μm.
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Figure 3: Immunolocalization of pEg7 in Xenopus Xl2 culture cells. The cells were observed in phase contrast (A, D, G, J, M, P, S), and DNA was stained with DAPI (B, E, H, K, N, Q, T). pEg7 was detected by indirect immunofluorescence using purified anti–pEg7 G antibodies (C, F, I, L, O, R, U). (S) Arrow indicates the midbody. Bar, 10 μm.

Mentions: The abundance of pEg7 in both eggs and testis suggests that the expression of this protein is correlated with the mitotic activity of cells. Therefore, the subcellular distribution of pEg7 in Xl2 Xenopus cells was examined at different stages of the cell cycle by indirect immunofluorescence microscopy. The specificity of antibodies was first tested by Western blot, using Xl2 cell extracts (Fig. 2 c). Purified P1 and G antibodies both detected the 150-kD polypeptide. Since the purified G antibody detected no additional bands, this was used for immunolocalization experiments (Fig. 3).


pEg7, a new Xenopus protein required for mitotic chromosome condensation in egg extracts.

Cubizolles F, Legagneux V, Le Guellec R, Chartrain I, Uzbekov R, Ford C, Le Guellec K - J. Cell Biol. (1998)

Immunolocalization of  pEg7 in Xenopus Xl2 culture  cells. The cells were observed in  phase contrast (A, D, G, J, M, P,  S), and DNA was stained with  DAPI (B, E, H, K, N, Q, T).  pEg7 was detected by indirect  immunofluorescence using purified anti–pEg7 G antibodies (C,  F, I, L, O, R, U). (S) Arrow indicates the midbody. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132990&req=5

Figure 3: Immunolocalization of pEg7 in Xenopus Xl2 culture cells. The cells were observed in phase contrast (A, D, G, J, M, P, S), and DNA was stained with DAPI (B, E, H, K, N, Q, T). pEg7 was detected by indirect immunofluorescence using purified anti–pEg7 G antibodies (C, F, I, L, O, R, U). (S) Arrow indicates the midbody. Bar, 10 μm.
Mentions: The abundance of pEg7 in both eggs and testis suggests that the expression of this protein is correlated with the mitotic activity of cells. Therefore, the subcellular distribution of pEg7 in Xl2 Xenopus cells was examined at different stages of the cell cycle by indirect immunofluorescence microscopy. The specificity of antibodies was first tested by Western blot, using Xl2 cell extracts (Fig. 2 c). Purified P1 and G antibodies both detected the 150-kD polypeptide. Since the purified G antibody detected no additional bands, this was used for immunolocalization experiments (Fig. 3).

Bottom Line: This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation.A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts.Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

View Article: PubMed Central - PubMed

Affiliation: Biologie et Génétique du Développement, CNRS UPR 41, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France.

ABSTRACT
We have isolated a cDNA, Eg7, corresponding to a Xenopus maternal mRNA, which is polyadenylated in mature oocytes and deadenylated in early embryos. This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation. The tissue and cell expression pattern of pEg7 indicates that this protein is only readily detected in cultured cells and germ cells. Immunolocalization in Xenopus cultured cells indicates that pEg7 concentrates onto chromosomes during mitosis. A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts. Incubating these extracts with antibodies directed against two distinct parts of pEg7 provokes a strong inhibition of the condensation and resolution of mitotic chromosomes. Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

Show MeSH
Related in: MedlinePlus