A Comparison of the Development of Nucleate and Non-Nucleate Eggs of Arbacia Punctulata

Harvey, Ethel Browne

doi:10.2307/1537837

Cited by 78 publications

(21 citation statements)

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“…In cultured mammalian cells and many zygotes, blockage of DNA replication (19,33,37) or removal of the nucleus (26) has been found to prevent pole duplication. On the other hand, several cycles of spindle pole duplication were found to occur in the zygotes of some invertebrates after similar treatments (16,17,48,57), making it difficult to specify the role that nuclear processes play in spindle pole regulation when these approaches were used.A genetic approach for examining the regulation of spindle pole duplication has been taken in the yeast Saccharomyces cerevisiae by analyzing temperature-sensitive cdc (cell division cycle) mutants for behavior of the spindle pole body (SPB), which serves as the sole microtubule-organizing center. Generally, cdc mutations that inhibit cellular and nuclear division also impede further duplication of the SPBs so that each cell contains the number of SPBs (one or two) appropriate for its stage of progression through the cell cycle at arrest (8).…”

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A yeast gene essential for regulation of spindle pole duplication.

Baum¹,

Yip²,

Goetsch³

et al. 1988

Mol. Cell. Biol.

134

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In eucaryotic cells, duplication of spindle poles must be coordinated with other cell cycle functions. We report here the identification in Saccharomyces cerevisiae of a temperature-sensitive lethal mutation, espl, that deregulates spindle pole duplication. Mutant cells transferred to the nonpermissive temperature became unable to continue DNA synthesis and cell division but displayed repeated duplication of their spindle pole bodies. (12,40,55) suggests that continued duplication may be regulated by entrainment to other stage-specific events of the cycle. The possibility that spindle pole duplication is dependent on chromosomal replication, for example, has been analyzed experimentally. In cultured mammalian cells and many zygotes, blockage of DNA replication (19,33,37) or removal of the nucleus (26) has been found to prevent pole duplication. On the other hand, several cycles of spindle pole duplication were found to occur in the zygotes of some invertebrates after similar treatments (16,17,48,57), making it difficult to specify the role that nuclear processes play in spindle pole regulation when these approaches were used.A genetic approach for examining the regulation of spindle pole duplication has been taken in the yeast Saccharomyces cerevisiae by analyzing temperature-sensitive cdc (cell division cycle) mutants for behavior of the spindle pole body (SPB), which serves as the sole microtubule-organizing center. Generally, cdc mutations that inhibit cellular and nuclear division also impede further duplication of the SPBs so that each cell contains the number of SPBs (one or two) appropriate for its stage of progression through the cell cycle at arrest (8). Similarly, if DNA replication is inhibited by the drug hydroxyurea or microtubule formation is prevented by treatment with nocodazole, nuclear division is blocked and no further SPB duplication ensues (8,36 depends on the successful completion of nuclear division itself (35).Analysis of mutations that alter the regulation of spindle pole duplication may help to clarify the mechanisms coordinating duplication with other cell cycle processes. Electron microscopy (9, 30) demonstrates that in yeast cells the SPB normally duplicates before chromosomal replication at a stage in the G1 phase of the cell cycle, termed Start, when commitment to division occurs (15). However, mutations in the gene CDC31 cause an uncoupling of the normal relationship between SPB duplication and DNA synthesis, SPB duplication failing to occur despite the occurrence of budding and DNA replication (7). As a consequence, haploid cdc3l mutants transiently subjected to the nonpermissive temperature generate diploids and cells of even higher ploidy (7,45

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confidence: 99%

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A yeast gene essential for regulation of spindle pole duplication.

Baum¹,

Yip²,

Goetsch³

et al. 1988

Mol. Cell. Biol.

134

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“…From this approach, she learned that each egg fragment was capable of fertilization and development regardless of whether it contained the egg pronucleus, either as a diploid organism (male and female pronuclear contributions), as a merogone (an enucleated egg fragment that was fertilized), or even as a parthenogenetically activated merogone (with no nucleus). These experiments documented that early cleavage and development can occur in this animal even in the absence of a nucleus and that maternal information was important in early development (Harvey, 1940). Earlier, Theodor Boveri, while working at Stazione Zoologica Anton Dohrn di Napoli, even made use of sea urchin merogones fertilized by the sperm of other species to distinguish between contributions from the maternal stores, relative to the paternal nucleus (Boveri, 1893; Laubichler & Davidson, 2008).…”

Section: General Activation Of the Embryonic Genomementioning

confidence: 85%

Germ Line Versus Soma in the Transition from Egg to Embryo

Swartz

Wessel

2015

Current Topics in Developmental Biology

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With few exceptions, all animals acquire the ability to produce eggs or sperm at some point in their lifecycle. Despite this near universal requirement for sexual reproduction, there exists an incredible diversity in germ-line development. For example, animals exhibit a vast range of differences in the timing at which the germ line, which retains reproductive potential, separates from the soma, or terminally differentiated, non-reproductive cells. This separation may occur during embryonic development, after gastrulation, or even in adults, depending on the organism. The molecular mechanisms of germ line segregation are also highly diverse, and intimately intertwined with the overall transition from a fertilized egg to an embryo. The earliest embryonic stages of many species are largely controlled by maternally supplied factors. Later in development, patterning control shifts to the embryonic genome and, concomitantly with this transition, the maternally supplied factors are broadly degraded. This chapter attempts to integrate these processes – germ line segregation, and how the divergence of germ line and soma may utilize the egg to embryo transitions differently. In some embryos, this difference is subtle or maybe lacking altogether, whereas in other embryos, this difference in utilization may be a key step in the divergence of the two lineages. Here we will focus our discussion on the echinoderms, and in particular the sea urchins, in which recent studies have provided mechanistic understanding in germ line determination. We propose that the germ line in sea urchins requires an acquisition of maternal factors from the egg and, when compared to other members of the taxon, this appears to be a derived mechanism. The acquisition is early – at the 32 cell stage – and involves active protection of maternal mRNAs, which are instead degraded in somatic cells with the maternal to embryonic transition. We collectively refer to this model as the Time Capsule method for germ line determination.

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“…Furthermore, if the nucleus is removed from a fertilized frog egg, the enucleated cell continues to undergo periodic cortical contractions at 30-min intervals, as if it were trying to divide (7). Enucleated sea urchin eggs even undergo cleavage and develop into abnormal blastulas (8). As Mazia (9) puts it, the cell cycle is really a cell "bicycle;" the two wheels are the growth cycle and the division cycle, which normally turn in a 1:1 ratio but may turn independently.…”

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Modeling the cell division cycle: cdc2 and cyclin interactions.

Tyson

1991

Proc. Natl. Acad. Sci. U.S.A.

391

304

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The proteins cdc2 and cyclin form a heterodimer (maturation promoting factor) that controls the major events of the cell cycle. A mathematical model for the interactions of cdc2 and cyclin is constructed. Simulation and analysis of the model show that the control system can operate in three modes: as a steady state with high maturation promoting factor activity, as a spontaneous oscillator, or as an excitable switch.We associate the steady state with metaphase arrest in unfertilized eggs, the spontaneous oscillations with rapid division cycles in early embryos, and the excitable switch with growthcontrolled division cycles typical of nonembryonic cells.

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A Comparison of the Development of Nucleate and Non-Nucleate Eggs of Arbacia Punctulata

Cited by 78 publications

References 12 publications

A yeast gene essential for regulation of spindle pole duplication.

A yeast gene essential for regulation of spindle pole duplication.

Germ Line Versus Soma in the Transition from Egg to Embryo

Modeling the cell division cycle: cdc2 and cyclin interactions.

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