Artificial Parthenogenesis in Starfish Eggs: Behavior of Nuclei and Chromosomes Resulting in Tetraploidy of Parthenogenotes Produced by the Suppression of Polar Body Extrusion

Washitani-Nemoto, Setsuko; Saitoh, Chiemi; Nemoto, Shin-ichi

doi:10.1006/dbio.1994.1148

Cited by 30 publications

(26 citation statements)

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“…Although some eggs subsequently showed multiple nuclei or irregular cleavage, no further development was observed. The failure of the Src-injected eggs to undergo normal cell division and development might be due to the absence of the sperm centriole that normally provides the mitosis organizing center in the fertilized egg (42).…”

Section: Injection Of Starfish Eggs With Kinase Active Src Protein Camentioning

confidence: 99%

Evidence That Fertilization Activates Starfish Eggs by Sequential Activation of a Src-like Kinase and Phospholipase Cγ

Giusti

Hinkle

et al. 2000

Journal of Biological Chemistry

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At fertilization, signals at the site of sperm-egg interaction cause a rise in cytosolic Ca 2ϩ (1,2). This opens ion channels and stimulates exocytosis of cortical granules, resulting in blocks to polyspermy, and also stimulates the resumption of the cell cycle (3-5). The Ca 2ϩ rise results, at least in large part, from Ca 2ϩ release from the endoplasmic reticulum, mediated by inositol 1,4,5-trisphosphate (IP 3 ) 1 (6 -10). Much recent work on fertilization has focused on the signal transduction pathways that lead to IP 3 production.The phospholipase C family of enzymes produces IP 3 and diacylglycerol from the membrane lipid phosphatidylinositol 4,5-bisphosphate (11). In echinoderm eggs, it is the ␥ isoform of phospholipase C (PLC␥) that functions at fertilization. PLC␥ enzyme activity increases by 30 s post-fertilization in sea urchin eggs (12), and inhibition of PLC␥ activation inhibits Ca 2ϩ release at fertilization in both sea urchin and starfish eggs (13)(14)(15). In these experiments, PLC␥ activity was inhibited by injection of eggs with excess Src homology 2 (SH2) domains of PLC␥. SH2 domains are found in many signaling proteins, and provide a site for specific interaction of a particular protein with a particular phosphorylated tyrosine on another protein (16). Excess SH2 domains, introduced into cells by microinjection, function as specific dominant negative inhibitors of such interactions.PLC␥ can be activated by phosphorylation of a regulatory tyrosine, although other factors may also be significant (17)(18)(19)(20). In sea urchin eggs, attempts to determine if PLC␥ is tyrosine phosphorylated at fertilization have been inconclusive, since the phosphotyrosine in PLC␥ immunoprecipitates was barely detectable either before or after fertilization (12, 21). As discussed by these authors, a local increase at the site of spermegg interaction might have been too small to detect by the methods used. Nevertheless, tyrosine kinase activity increases within 15 s after fertilization (22), and the tyrosine kinase inhibitor genistein delays Ca 2ϩ release at fertilization (23). One group of tyrosine kinases that participates, directly or indirectly, in activation of PLC␥ is the Src family (20, 24 -26), and in vitro experiments with starfish eggs have shown a fertilization-dependent association of a Src-like kinase with the SH2 domains of PLC␥ (27). Further evidence that a Src family kinase functions to activate PLC␥ at fertilization comes from findings that in both starfish and sea urchin eggs, injection of excess SH2 domains of Src family kinases inhibits Ca 2ϩ release at fertilization (28,29). In addition, in sea urchin eggs, the Src family kinase inhibitor PP1 delays Ca 2ϩ release at fertilization, and the activity of a Src-like kinase increases by 30 s postinsemination (29).These findings indicate that a Src-like kinase may, directly or through intermediate molecules, activate PLC␥ at fertilization, leading to Ca 2ϩ release and egg activation. In this report, we examine four questions related to this model. 1) I...

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Section: Injection Of Starfish Eggs With Kinase Active Src Protein Camentioning

confidence: 99%

Evidence That Fertilization Activates Starfish Eggs by Sequential Activation of a Src-like Kinase and Phospholipase Cγ

Giusti

Hinkle

et al. 2000

Journal of Biological Chemistry

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“…The absence of pronuclear fusion or polar body extrusion may also be responsible for the more rapid progress of this parthenogenetic development. Considerable work has been done examining induced parthenogenesis in starfish (Obata and Nemoto, 1984;Washitani-Nemoto et al, 1994), who found a different situation. They found that parthenogenetically developing eggs reached cleavage slower than the spermfertilised controls, due to the de novo formation of the centrosomes.…”

Section: Discussionmentioning

confidence: 99%

Impact of pH on oocyte fertilisation and the overrun of meiotic checkpoints leading to parthenogenetic development inNereis virens

Bouch¹,

Olive²

2005

Invertebrate Reproduction & Development

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Whilst developing a fertilisation assay to quantify the onset of fertilisability in oocytes from cultured Nereis virens, development through to the blastula stage was observed within the negative control. In the absence of sperm, some oocytes re-initiated the cell cycle without fertilisation which is the usual cue in this species. Investigations showed that a lower pH of 6.6 significantly increased the incidence of this parthenogenetic development which was also observed to be more rapid than was observed in normal sperm fertilised development. Cleavage was reached within 3 h if no sperm were present, but took longer when the oocytes were fertilised with sperm. The parthenogenetic development is symptomatic of a breakdown between the environmental cues that would cause final maturation and spawning in wild animals and the re-initiation of meiosis. In culture systems, where sufficient environmental cues may be lacking, oocytes can attain an overripe "trigger happy" state where minor shocks can initiate development in the absence of sperm. The avoidance of this state in cultured animals is therefore an important management objective.

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“…2E) were used for the electric fusion process. It is known that a normally matured egg with both PB1 and PB2 will not cleave even after activation without sperm, indicating the absence of reproductive centrioles (Obata and Nemoto, 1984;Washitani-Nemoto et al, 1994;Tamura and Nemoto, 2001;Uetake et al, 2002).…”

Section: Preparation Of Mature Eggs As Centrosome Recipientsmentioning

confidence: 99%

“…Artificial parthenogenesis in starfish was pioneered in the early 1980s by Obata and Nemoto (Obata and Nemoto, 1984) and later, Washitani-Nemoto et al (Washitani-Nemoto et al, 1994) found that suppression of polar body (PB) extrusions in artificially activated oocytes induces parthenogenetic development, whereas eggs that matured normally did not develop, even with artificial activation. They suggested that the meiotic centrosomes retained in the eggs by the failure of PB extrusion are diverted to mitosis-organizing centers in the mitotic spindle, resulting in parthenogenetic development.…”

Section: Introductionmentioning

confidence: 99%

“…Washitani- Nemoto et al (Washitani-Nemoto et al, 1994), Uetake et al (Uetake et al, 2002) and Zhang et al (Zhang et al, 2004) utilized the suppression of PB extrusion as a useful tool for analysing the mechanism of the 'paternal inheritance of the centrosomes in development', first noted by Boveri (Boveri, 1887). As we know, control of the centrosome inheritance is an issue of fundamental importance for all sexually reproductive organisms.…”

Section: Introductionmentioning

confidence: 99%

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Centrosome destined to decay in starfish oocytes

Shirato

Tamura

Yoneda³

et al. 2006

Development

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In contrast to the somatic cell cycle, duplication of the centrioles does not occur in the second meiotic cycle. Previous studies have revealed that in starfish each of the two centrosomes in fully-grown immature oocytes consists of two centrioles with different destinies: one survives and retains its reproductive capacity, and the other is lost after completion of meiosis. In this study, we investigated whether this heterogeneity of the meiotic centrioles is already determined before the re-initiation of meiosis. We prepared a small fragment of immature oocyte containing the four centrioles and fused it electrically with a mature egg in order to transfer two sets of the premeiotic centrioles into the mature cytoplasm. Two asters were present in this conjugate, and in each of them only a single centriole was detected by electron microscopy. In the first mitosis of the conjugate artificially activated without sperm, two division poles formed, each of which doubled in each subsequent round of mitosis. These results indicate that only two of the four premeiotic centrioles survived in the mature cytoplasm and that they retained their reproductive capacity, which suggests that the heterogeneity of the maternal centrioles is determined well before re-initiation of meiosis,and that some factor in the mature cytoplasm is responsible for suppressing the reproductive capacity of the centrioles destined to decay.

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Artificial Parthenogenesis in Starfish Eggs: Behavior of Nuclei and Chromosomes Resulting in Tetraploidy of Parthenogenotes Produced by the Suppression of Polar Body Extrusion

Cited by 30 publications

References 0 publications

Evidence That Fertilization Activates Starfish Eggs by Sequential Activation of a Src-like Kinase and Phospholipase Cγ

Evidence That Fertilization Activates Starfish Eggs by Sequential Activation of a Src-like Kinase and Phospholipase Cγ

Impact of pH on oocyte fertilisation and the overrun of meiotic checkpoints leading to parthenogenetic development inNereis virens

Centrosome destined to decay in starfish oocytes

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