Hinchcliffe EH , Cassels GO , Rieder CL , Sluder G .

R01 GM040198-15 NIGMS NIH HHS , GM 40198 NIGMS NIH HHS , R01 GM040198 NIGMS NIH HHS , GM 30758 NIGMS NIH HHS , NCRR-01219 NCRR NIH HHS , T32 HD007312 NICHD NIH HHS , R01 GM030758 NIGMS NIH HHS , R37 GM040198 NIGMS NIH HHS

	Figure 2. Repeated centrosome reproduction with high Cdk1-B activity in a zygote arrested in S phase with aphidicolin. Here we have focused on one aster that has separated from the nucleus and doubles twice starting 221 min after fertilization. (a) Four asters at the nucleus; one aster is detaching (arrow). (b) The detached aster migrates away from the nucleus. (c) The detached aster has begun to double. (d) This aster has split into two asters (arrows). (e) These asters split again (arrows); the fourth aster is out of the plane of focus. Minutes after fertilization are shown in the lower corner of each frame. Polarization optics. 10 μm per scale division.
	Figure 3. Microinjection of cyclin B Δ-90 mRNA at first prophase arrests zygotes in mitosis. (a) The zygote enters mitosis and forms a normal bipolar spindle. The refractile sphere in the lower left portion of the zygote is a drop of oil used to cap the micropipet. (b) Anaphase onset occurs at the normal time. (c) Both of the spindle poles have split and a tetrapolar spindle forms. (d) This zygote shortly before fixation for serial section ultrastructural analysis. (e) Each spindle pole of this zygote contains only a single centriole. All four centrioles in this zygote are shown in this frame. (a–d) Polarization optics. Minutes after fertilization are shown in the lower left corner of each frame. 10 μm per scale division. Bar: (e) 0.25 μm.
	Figure 4. Anaphase chromosome disjunction in a zygote injected with cyclin B Δ-90 mRNA. (a–c) Polarization micrographs. (d–f) Fluorescence micrographs of the chromosomes of the same cell at the same times. (a and d) A normal prometaphase spindle has formed, with the chromosomes aligned at the metaphase plate. The oil droplet used to cap the injection needle can be seen below the spindle. (b and e) Mid-anaphase. The sister chromatids have disjoined and are moving towards the spindle poles. (c and f) Both spindle poles have split, and a tetrapolar spindle has formed. The disjoined chromatids are dispersed throughout the central region of the tetrapolar spindle. Minutes after fertilization are shown in the lower left corner of the lower frames. 10 μm per scale division.
	Figure 5. Histone H1 kinase activity in zygotes treated with protein synthesis inhibitors (E/A) beginning before fertilization (diamonds) and at prophase of first mitosis (squares). Both cultures came from a common pool of zygotes. The arrow (F) indicates time of fertilization. Note that the first time point for each experiment was taken 15 min before fertilization and represents the basal level of H1 kinase activity in unfertilized eggs. Each data point represents the average histone H1 kinase activity for two samples taken at each time. The two curves represent actual PhosphorImager values and were not normalized to each other. Ordinate: H1 kinase activity expressed as “volume,” which is the sum of the pixel values of the H1 band minus background as determined in the PhosphorImager. Abscissa: minutes after fertilization.
	Figure 6. The development of a zygote treated with protein synthesis inhibitors beginning at first prophase. (a) Prometaphase. (b) Anaphase. (c) Initiation of cytokinesis at telophase. (d) The blastomeres arrest in interphase of the second cell cycle, and the nuclei become enlarged over time. The two asters in each blastomere are weakly birefringent and thus not visible in this micrograph. (e) Another zygote from the same culture, also arrested in second interphase. This zygote has been treated with 2% hexylene glycol to augment astral birefringence. Minutes after fertilization are shown in the lower corner of each panel. Polarization optics. 10 μm per scale division.
	Figure 7. Serial semithick section ultrastructural analysis of centrosomes in two zygotes treated with protein synthesis inhibitors at first prophase. (a–c) Zygote fixed 164 min after fertilization. (a, upper inset) Zygote before fixation. Three centrosomes were completely reconstructed, and each contained two centrioles (a–c). The lower inset in a shows the second centriole in this centrosome, which was located in a different section. The profile of the nuclear envelope can be seen to the left of the lower inset. (d–g) Zygote fixed 345 min after fertilization. (d, inset) Zygote just before fixation; the refractile spheres are oil drops used to mark the zygote for recovery and fixation. All four centrosomes in this zygote were reconstructed, and each contained two centrioles (d–g). All four centrosomes are close to the nuclear envelopes, which are seen running vertically through the center of each panel. (a and d, insets) Polarization optics. 10 μm per scale division. Bar, 2 μm.
	Figure 8. Indirect immunofluorescence using anti-BrdU antibody to assay for DNA synthesis. (a) Nuclear region of a control zygote fixed 50 min after fertilization. (b) Nuclear region of a zygote treated with protein synthesis inhibitors at fertilization and fixed 50 min later. (c) Polarization micrograph of a zygote treated with protein synthesis inhibitors at fertilization and refertilized 180 min after fertilization. Note that the asters associated with the nucleus have reproduced. The late entering sperm pronucleus with its sperm aster can be seen on the left. Minutes after refertilization are indicated in the lower corner of this frame. (d) Anti-BrdU immunofluorescence of a refertilized zygote from the same culture as c. Note that both the zygote nucleus and the late-entering sperm pronucleus have incorporated BrdU. Minutes after refertilization are indicated in the lower corner of this frame. (a, b, and d) Fluorescence optics. (c) Polarization optics. 10 μm per scale division.
	Figure 9. Indirect immunofluorescence using an anti-BrdU antibody to assay for DNA synthesis. (a) This zygote was treated with translation inhibitors and BrdU at first prophase (55 min after fertilization) and fixed 120 min later when it was arrested in second interphase. There is no incorporation of BrdU into nuclear DNA. Background cytoplasmic fluorescence has become evident due to the long camera exposure used. (b) Control for BrdU permeability in prophase zygotes. BrdU was applied in first prophase (55 min after fertilization) and translation inhibitors were applied at telophase (90 min after fertilization) when second DNA synthesis had begun. The zygotes were fixed 120 min later. Incorporation of BrdU into nuclear DNA, as shown here, indicates that BrdU enters prophase/mitotic zygotes. Fluorescence optics. 10 μm per scale division.

Amon, Regulation of p34CDC28 tyrosine phosphorylation is not required for entry into mitosis in S. cerevisiae. 1992, Pubmed

Amon, Regulation of p34CDC28 tyrosine phosphorylation is not required for entry into mitosis in S. cerevisiae. 1992, Pubmed
Arion, cdc2 is a component of the M phase-specific histone H1 kinase: evidence for identity with MPF. 1988, Pubmed , Echinobase
Aubin, Variations in the distribution and migration of centriole duplexes in mitotic PtK2 cells studied by immunofluorescence microscopy. 1980, Pubmed
Balczon, Dissociation of centrosome replication events from cycles of DNA synthesis and mitotic division in hydroxyurea-arrested Chinese hamster ovary cells. 1995, Pubmed
Biggins, Yeast ubiquitin-like genes are involved in duplication of the microtubule organizing center. 1996, Pubmed
Cawood, A comparison of the use of bromodeoxyuridine and [3H]thymidine in studies of the cell cycle. 1983, Pubmed
Dahmann, S-phase-promoting cyclin-dependent kinases prevent re-replication by inhibiting the transition of replication origins to a pre-replicative state. 1995, Pubmed
Epel, Activation of an Na + -dependent amino acid transport system upon fertilization of sea urchin eggs. 1972, Pubmed , Echinobase
Fuseler, Repetitive procurement of mature gametes from individual sea stars and sea urchins. 1973, Pubmed , Echinobase
Gard, Centrosome duplication continues in cycloheximide-treated Xenopus blastulae in the absence of a detectable cell cycle. 1990, Pubmed
Gautier, Cyclin is a component of maturation-promoting factor from Xenopus. 1990, Pubmed
Genevière-Garrigues, Active cyclin B-cdc2 kinase does not inhibit DNA replication and cannot drive prematurely fertilized sea urchin eggs into mitosis. 1995, Pubmed , Echinobase
Glotzer, Cyclin is degraded by the ubiquitin pathway. 1991, Pubmed
Gunduz, The use of FITC-conjugated monoclonal antibodies for determination of S-phase cells with fluorescence microscopy. 1985, Pubmed
HARRIS, Some structural and functional aspects of the mitotic apparatus in sea urchin embryos. 1962, Pubmed , Echinobase
HINEGARDNER, THE DNA SYNTHETIC PERIOD DURING EARLY DEVELOPMENT OF THE SEA URCHIN EGG. 1964, Pubmed , Echinobase
Hayles, Temporal order of S phase and mitosis in fission yeast is determined by the state of the p34cdc2-mitotic B cyclin complex. 1994, Pubmed
Heald, Human wee1 maintains mitotic timing by protecting the nucleus from cytoplasmically activated Cdc2 kinase. 1993, Pubmed
Holloway, Anaphase is initiated by proteolysis rather than by the inactivation of maturation-promoting factor. 1993, Pubmed
Ikegami, Aphidicolin prevents mitotic cell division by interfering with the activity of DNA polymerase-alpha. 1978, Pubmed , Echinobase
Ikegami, Inhibition by aphidicolin of cell cycle progression and DNA replication in sea urchin embryos. 1979, Pubmed , Echinobase
Kiehart, Microinjection of echinoderm eggs: apparatus and procedures. 1982, Pubmed , Echinobase
King, How proteolysis drives the cell cycle. 1996, Pubmed
Kochanski, Mode of centriole duplication and distribution. 1990, Pubmed
Kuriyama, Centriole cycle in Chinese hamster ovary cells as determined by whole-mount electron microscopy. 1981, Pubmed
Labbé, MPF from starfish oocytes at first meiotic metaphase is a heterodimer containing one molecule of cdc2 and one molecule of cyclin B. 1989, Pubmed , Echinobase
Lamb, Microinjection of p34cdc2 kinase induces marked changes in cell shape, cytoskeletal organization, and chromatin structure in mammalian fibroblasts. 1990, Pubmed
Lange, A molecular marker for centriole maturation in the mammalian cell cycle. 1995, Pubmed
Luca, Both cyclin A delta 60 and B delta 97 are stable and arrest cells in M-phase, but only cyclin B delta 97 turns on cyclin destruction. 1991, Pubmed , Echinobase
Mahbubani, Cell cycle regulation of the replication licensing system: involvement of a Cdk-dependent inhibitor. 1997, Pubmed
Mazia, The Multiplicity of the Mitotic Centers and the Time-Course of Their Duplication and Separation. 1960, Pubmed , Echinobase
McDonald, A proteasome cap subunit required for spindle pole body duplication in yeast. 1997, Pubmed
Murray, The role of cyclin synthesis and degradation in the control of maturation promoting factor activity. 1989, Pubmed
Murray, Cyclin ubiquitination: the destructive end of mitosis. 1995, Pubmed
Murray, Cyclin synthesis drives the early embryonic cell cycle. 1989, Pubmed
Raff, Nuclear and cytoplasmic mitotic cycles continue in Drosophila embryos in which DNA synthesis is inhibited with aphidicolin. 1988, Pubmed
Rattner, Independence of centriole formation and DNA synthesis. 1973, Pubmed
Rempel, Maternal Xenopus Cdk2-cyclin E complexes function during meiotic and early embryonic cell cycles that lack a G1 phase. 1995, Pubmed
Robbins, The centriole cycle in synchronized HeLa cells. 1968, Pubmed
Satterwhite, Phosphorylation of myosin-II regulatory light chain by cyclin-p34cdc2: a mechanism for the timing of cytokinesis. 1992, Pubmed
Sluder, Protein synthesis and the cell cycle: centrosome reproduction in sea urchin eggs is not under translational control. 1990, Pubmed , Echinobase
Sluder, Feedback control of the metaphase-anaphase transition in sea urchin zygotes: role of maloriented chromosomes. 1994, Pubmed , Echinobase
Sluder, Experimental analysis of the reproduction of spindle poles. 1985, Pubmed , Echinobase
Sluder, Relationship between nuclear DNA synthesis and centrosome reproduction in sea urchin eggs. 1987, Pubmed , Echinobase
Sluder, Centriole number and the reproductive capacity of spindle poles. 1985, Pubmed , Echinobase
Sluder, The reproduction of centrosomes: nuclear versus cytoplasmic controls. 1986, Pubmed , Echinobase
Sluder, Nuclear envelope breakdown is under nuclear not cytoplasmic control in sea urchin zygotes. 1995, Pubmed , Echinobase
Sorger, S-phase feedback control in budding yeast independent of tyrosine phosphorylation of p34cdc28. 1992, Pubmed
Strausfeld, Both cyclin A and cyclin E have S-phase promoting (SPF) activity in Xenopus egg extracts. 1996, Pubmed
Suprynowicz, Ca2+ triggers premature inactivation of the cdc2 protein kinase in permeabilized sea urchin embryos. 1994, Pubmed , Echinobase
Tournier, Centrosomes competent for parthenogenesis in Xenopus eggs support procentriole budding in cell-free extracts. 1991, Pubmed
Wagenaar, The timing of synthesis of proteins required for mitosis in the cell cycle of the sea urchin embryo. 1983, Pubmed , Echinobase
Wheatley, CDK1 inactivation regulates anaphase spindle dynamics and cytokinesis in vivo. 1997, Pubmed