PROPHASING OF INTERPHASE NUCLEI AND INDUCTION OF NUCLEAR ENVELOPES AROUND METAPHASE CHROMOSOMES IN H<scp>E</scp>L<scp>A</scp> AND CHINESE HAMSTER HOMO- AND HETEROKARYONS

Obara, Yoshitaka; Chai, Lee S.; Weinfeld, Herbert; Sandberg, Avery A.

doi:10.1083/jcb.62.1.104

Cited by 37 publications

(20 citation statements)

References 14 publications

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“…Some of these characteristics distinguish them from the mitotic factors (40). The pH dependency ofthese factors is also in agreement with the results of the early cell fusion experiments of Obara and co-workers (21)(22)(23), which suggested that high pH favored "telophasing" and low pH "prophasing" or premature chromosome condensation . Our own studies (Hittelman and Rao, unpublished data) show that the frequency of premature chromosome condensation induction is much higher if a low pH is maintained during the collection of mitotic cells and subsequent fusion procedures.…”

Section: Discussionsupporting

confidence: 87%

Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Adlakha¹,

Sahasrabuddhe²,

Wright³

et al. 1983

The Journal of Cell Biology

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Our earlier studies indicated that the mitotic factors, which induce germinal vesicle breakdown and chromosome condensation when injected into fully grown Xenopus oocytes, are preferentially associated with metaphase chromosomes and that they bind to chromatin as soon as they are synthesized during the G2 phase . In this study, we attempted to determine the fate of these factors as the cell completes mitosis and enters G, . Extracts from HeLa cells at different points during G,, S, and G2 periods were mixed with mitotic extracts in various proportions, incubated, and then injected into Xenopus oocytes to determine their maturationpromoting activity. The maturation-promoting activity of the mitotic extracts was neutralized by extracts of G, cells during all stages of G, but not by those of late S and G 2 phase cells . Extracts of quiescent (Go) human diploid fibroblasts exhibited very little inhibitory activity . However, UV irradiation of G o cells, which is known to cause decondensation of chromatin, significantly enhanced the inhibitory activity of extracts of these cells. These factors are termed inhibitors of mitotic factors (IMF) . They seem to be activated, rather than newly synthesized, as the cell enters telophase when chromosomes begin to decondense. The IMF are nondialyzable, nonhistone proteins with a molecular weight of >12,000 . Since mitotic factors are known to induce chromosome condensation, it is possible that IMF, which are antagonistic to mitotic factors, may serve the reverse function of the mitotic factors, i.e ., regulation of chromosome decondensation .Chromatin undergoes profound structural alterations during the cell cycle . During mitosis, it is supercoiled and condensed to form the mitotic chromosomes. Chromosome condensation is a critical event in the cell cycle that is necessary for the equal distribution of genetic material between the daughter cells. The phenomenon of premature chromosome condensation described by Johnson and Rao (13) has been very useful in visualizing the state of chromatin condensation during interphase. Using this technique, Rao and Hanks (30) and Hanks and Rao (9) have shown that the process of chromosome decondensation, initiated during the telophase of mitosis, continues throughout the G, period until the chromatin reaches its ultimate state ofdecondensation by the end of G,, when DNA synthesis is initiated .As for the factors involved in chromosome condensation, studies from this and other laboratories have demonstrated that when extracts from mitotic HeLa cells (39,40) or mitotic Chinese hamster ovary cells (19) are injected into Xenopus THE JOURNAL OF CELL BIOLOGY -VOLUME 97 DECEMBER 1983 1707-1713 C The Rockefeller University Press -0021-9525/83/12/1707/07 $1 .00 laevis oocytes, they exhibit maturation-promoting activity (MPA)' as evidenced by germinal vesicle breakdown (GVBD) and condensation of chromosomes. These studies also revealed that the mitotic factors are nonhistone proteins and accumulate slowly in the beginning of G2, increase rapid...

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Section: Discussionsupporting

confidence: 87%

Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Adlakha¹,

Sahasrabuddhe²,

Wright³

et al. 1983

The Journal of Cell Biology

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“…TLN were more frequently found in polykaryons containing many interphase nuclei. This observation conforms to earlier finding that low metaphase/ interphase ratio in fused cells promotes nuclear membrane formation around metaphase chro mosomes (Obara et al 1974). Significant increase in the number of TLN up to 1.5hr incuba tion period is most probably due to membrane formation around metaphase chromosomes originated from asynchronic prophase nuclei.…”

Section: Resultssupporting

confidence: 80%

Mitotic Activity of Polykaryons Fused by Modified PEG-DMSO-Serum Method.

Manandhar

Khodjakov²,

Онищенко

1993

CYTOLOGIA

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“…The results of the above-cited experiments can be favorably compared to those obtained in cell-fusion studies using mitotic chromosome condensation (PCC) in a n interphase nucleus depends largely on the ratio of mitotic to interphase nuclei at the time of fusion (see Adlakha and Rao, 1987). After multiple fusion of several cells in G, phase with one metaphase cell, metaphase chromosomes decondense and a nuclear membrane starts to form around them (Obara et al, 1974). This process has been termed "telophasing," due to its resemblance to events in normal telophase.…”

Section: Nucleo-cytoplasmic Relationships Duringmentioning

confidence: 99%

Cell‐cycle aspects of growth and maturation of mammalian oocytes

Motlı́k

Kubelka

1990

Molecular Reproduction Devel

106

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In this review, recent data concerning growth and maturation of nonmammalian and mammalian female germ cells are compiled with regard to the increased understanding of somatic cells mitotic cycles, from yeast to human tissues. These data allow us to conclude that growing oocytes of nonvertebrates, lower vertebrates, and mammals resemble somatic cells in the G I In mammals, the LH surge induces "de novo" RNA and protein synthesis in granulosa cells. This metabolic change in granulosa cells abolishes their inhibitory activity, and meiosis in fully grown oocytes in preovulatory follicles is then resumed. Resumption of meiosis requires an activation of pre MPF molecules within oocytes. This can be achieved either without (mouse, rat, and rabbit) or with (pig, sheep, and cow) an active protein synthesis by the oocytes. The species specificity is probably dependent on the presence or absence of cyclin-like and/or mos-like molecules in fully grown oocytes. Both major events during GVBD, chromatin condensation, and nuclear envelope disintegration require protein phosphorylation. Experimentally, these two phosphorylation activities can be separated one from another. The active MPF molecules are amplified autocatalytically in amphibian and starfish oocytes. However, an increase of MPF activity in mouse and pig oocytes, similarly as in Rana pipiens and sturgeon oocytes, requires an active protein synthesis.

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PROPHASING OF INTERPHASE NUCLEI AND INDUCTION OF NUCLEAR ENVELOPES AROUND METAPHASE CHROMOSOMES IN HELA AND CHINESE HAMSTER HOMO- AND HETEROKARYONS

Cited by 37 publications

References 14 publications

Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells.

Mitotic Activity of Polykaryons Fused by Modified PEG-DMSO-Serum Method.

Cell‐cycle aspects of growth and maturation of mammalian oocytes

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