Related Experiment Video

Updated: Aug 19, 2026

Analysis of Apoptosis in Zebrafish Embryos by Whole-mount Immunofluorescence to Detect Activated Caspase 3
08:20

Analysis of Apoptosis in Zebrafish Embryos by Whole-mount Immunofluorescence to Detect Activated Caspase 3

Published on: December 20, 2013

Fertilization blocks apoptosis of starfish eggs by inactivation of the MAP kinase pathway

K Sasaki1, K Chiba

  • 1Department of Biology, Ochanomizu University, 2-1-1 Ohtsuka, Tokyo, 112-8610, Japan.

Developmental Biology
|August 24, 2001
PubMed

Insights

Starfish eggs undergo apoptosis if not fertilized, triggered by caspase-3 activation. Persistent Mos/MEK/MAP kinase signaling initiates this programmed cell death, which fertilization prevents.

Area of Science:

  • Reproductive biology
  • Cellular signaling
  • Apoptosis

Background:

  • Starfish oocytes arrest at meiosis I, resuming upon 1-methyladenine (1-MA) stimulation.
  • Fertilization is optimal between germinal vesicle breakdown (GVBD) and first polar body emission.
  • Unfertilized oocytes complete meiosis, yielding arrested eggs.

Purpose of the Study:

  • Investigate the fate of unfertilized starfish eggs.
  • Identify the molecular mechanisms triggering cell death in mature oocytes.
  • Determine the role of the Mos/MEK/MAP kinase pathway in apoptosis.

Main Methods:

  • Hormonal stimulation (1-MA) to induce oocyte maturation.
  • Monitoring caspase-3 activation and morphological changes (blebbing, fragmentation).
  • Pharmacological inhibition (MEK inhibitor, emetine) and recombinant protein injection (GST-Mos).

Main Results:

  • Spontaneous caspase-3 activation and apoptosis observed 9-12h post-1-MA in unfertilized eggs.
  • Apoptosis induction is dependent on Mos synthesis and MEK activity.
  • Persistent Mos/MEK/MAP kinase cascade activation signals cell death.
  • Fertilization inhibits the MAP kinase pathway, suppressing apoptosis.

Conclusions:

  • Unfertilized starfish eggs initiate apoptosis via caspase-3 activation.
  • The Mos/MEK/MAP kinase pathway is essential for triggering egg apoptosis.
  • Fertilization acts as a survival signal by inactivating this pathway.

More Related Videos

A Method for Microinjection of Patiria minata Zygotes08:48

A Method for Microinjection of Patiria minata Zygotes

Published on: September 1, 2014

Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment11:19

Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment

Published on: December 16, 2016

Related Concept Videos

Meiosis II01:57

Meiosis II

Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 chromosomes—one from each homologous initial pair. Importantly, each chromosome in these cells is composed of two joined copies, and when these cells enter meiosis II, the goal is to separate such sister chromatids using the same microtubule-based network employed in other division processes. The result of meiosis II is two haploid cells, each containing...
Fertilization01:38

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...