Fertilization in Aquatic Animals

Dale, Brian

doi:10.1007/978-1-4615-3830-1_16

Cited by 12 publications

(16 citation statements)

References 82 publications

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“…This regionalization may be found at the level of the extracellular coats, at the plasma membrane, or both (Dale, 1983). An obvious acellular structure for sperm entry is the micropyle, found in the chorion of fish, squid and insect eggs.…”

Section: Introductionmentioning

confidence: 96%

Is the human oocyte plasma membrane polarized?

et al. 1992

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Using scanning electron microscopy, we have shown that the plasma membrane of the human metaphase II oocyte is organized in evenly spaced, short microvilli of 1-3 fim in length. In contrast to other mammals studied to date, there is no microvillus-free area overlying the metaphase spindle and there were no other indications of polarization at this level of organization. Functional polarity of the plasma membrane, studied using localized microsurgery of the zona pelhicida followed by insemination, suggests that sperm fusion and entry in the human may occur anywhere over the oocyte surface. Aged oocytes and those exposed to acidic Tyrode's solution had surfaces which were not homogeneously covered by microvilli. Oocytes exposed to a sucrose solution and subzonally injected with spermatozoa showed evidence of partial cortical granule exocytosis.

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Section: Introductionmentioning

confidence: 96%

Is the human oocyte plasma membrane polarized?

et al. 1992

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“…In ascidians, mature eggs are arrested at the meta I stage (Dale, 1983), and 2 distinct sequences of [Ca 2 þ ] i oscillations are also observed after fertilization: phase I [Ca 2 þ ] i oscillations appear before the first polar body extrusion, and phase II [Ca 2 þ ] i oscillations appear between the extrusion of the first and second polar bodies (Brownlee and Dale, 1990;McDougall and Levasseur, 1998;Russo et al, 1996;Sensui and Morisawa, 1996;Speksnijder et al, 1989;Yoshida et al, 1998). The [Ca 2 þ ] i transients in the egg are crucial for the extrusion of the polar bodies (McDougall and Sardet, 1995;Sensui and Morisawa, 1996;Yoshida et al, 1998), and therefore, the ascidian egg is a good model for studying the relationship between meiosis and Ca 2 þ .…”

Section: Introductionmentioning

confidence: 99%

Role of Mos/MEK/ERK cascade and Cdk1 in Ca2+ oscillations in fertilized ascidian eggs

Sensui

Yoshida

Tachibana

2012

Developmental Biology

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Intracellular calcium ion concentration ([Ca(2+)](i)) transients are observed in the fertilized eggs of all species investigated so far, and are critical for initiating several events related to egg activation and cell cycle control. Here, we investigated the role of the Mos/MEK/ERK cascade and Cdk1 on Ca(2+) oscillations in fertilized ascidian eggs. The egg of the ascidian Phallusia nigra shows [Ca(2+)](i) oscillations after fertilization: Ca(2+) waves immediately following fertilization (phase I), and [Ca(2+)](i) oscillations between the first and second polar body extrusions (phase II). Our results show that in P. nigra eggs, ERK activity peaked just before the extrusion of the first polar body, and decreased gradually, eventually disappearing at the extrusion of the second polar body. Cyclin-dependent protein kinase 1(Cdk1) activity decreased to undetectable levels immediately after fertilization, and then periodically increased according to the meiotic and mitotic cell cycle. When the unfertilized eggs were incubated with U0126, an inhibitor of MEK, before insemination, ERK was immediately inactivated, and the phase II [Ca(2+)](i) oscillations disappeared. Alternatively, when the constitutively active Mos protein (GST-Mos) was injected into the unfertilized eggs, ERK activity was preserved for at least 120 min after fertilization, and the phase II [Ca(2+)](i) oscillations lasted for more than 120 min after the second polar body extrusion. These results suggest that ERK activity is necessary for maintaining [Ca(2+)](i) oscillations. GST-ΔN85-cyclin, which maintains Cdk1 activity, caused ERK activity in the eggs to persist for over 120 min after fertilization, and prolonged [Ca(2+)](i) oscillations. Moreover, the effects of GST-ΔN85-cyclin on the egg were abrogated by the application of U0126. Thus, Cdk1-mediated [Ca(2+)](i) oscillations seem to require ERK activity. However, GST-Mos triggered [Ca(2+)](i) oscillations after the second polar body extrusion, whereas GST-ΔN85-cyclin did not, although it prolongs the duration of [Ca(2+)](i) oscillations. Interestingly, GST-ΔN85-cyclin increased the frequency of [Ca(2+)](i) transients in the Mos-induced [Ca(2+)](i) oscillations after the extrusion of the second polar body. Thus, Cdk1 could maintain, but not activate, ERK and [Ca(2+)](i) oscillations. ERK activity and [Ca(2+)](i) oscillations seem to form a negative feedback loop which may be responsible for maintaining the meiotic period.

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“…Today we know that cytoplasmic maturity is, in part, synonymous with the metabolic status of the oocyte which continually changes, whether the oocyte is fertilized or left in culture medium (aging). Thus our newly collected MII oocytes appear synchronous with regards to nuclear maturation but are poised at various degrees of metabolic repression [7] and, by todays criteria, the best an embryologist can do is to inseminate or inject them at a pre-established time. All cells are dynamic and changes in the cytosol, such as membrane trafficking, are continual.…”

Section: Background To In Vitro Fertilizationmentioning

confidence: 98%

Trends, Fads and ART!

Dale¹,

Ménézo²,

Coppola³

2015

J Assist Reprod Genet

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Morphological selection techniques of gametes and embryos are of current interest to clinical practice in ART. Although intracytoplasmic morphologically selected sperm injection (IMSI), time lapse imaging morphometry (TLIM) or quantification of chromosome numbers (PGS) are potentially useful in research, they have not been shown to be of statistically predictive value and, thus, have only limited clinical usefulness. We make the point that morphological markers alone cannot predict the success of the early embryo, which depends on the correct orchestration of a myriad of physiological and biochemical activation events that progress independently of the maternal or zygotic genome. Since previous attempts to identify metabolic markers for embryo quality have failed and there is no evidence that the intrinsic nature of gametes and embryos can be improved in the laboratory, embryologists can only minimize environmental or operator induced damage while these cells are manipulated ex vivo.

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Fertilization in Aquatic Animals

Cited by 12 publications

References 82 publications

Is the human oocyte plasma membrane polarized?

Is the human oocyte plasma membrane polarized?

Role of Mos/MEK/ERK cascade and Cdk1 in Ca2+ oscillations in fertilized ascidian eggs

Trends, Fads and ART!

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