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Printable Handouts
Navigable Slide Index
- Introduction
- The fertilization process
- A mature mouse egg (oocyte)
- Fertilization in a mouse egg
- Meiotic arrest in different species
- Egg activation
- Calcium wave in fertilizing medaka egg
- Monitoring calcium wave using fluorescent dyes
- In vitro fertilization of mouse eggs
- Ca2+ oscillations during fertilization
- Plotting calcium changes
- Human IVF
- Calcium transients in different species
- How do sperm trigger Ca2+ release in the egg? (1)
- How do sperm trigger Ca2+ release in the egg? (2)
- What leads to sperm-induced Ca2+ increase?
- Sperm egg fusion in mice
- Mouse egg fertilization
- Measuring calcium in sperm with indo-1 dextran
- Gamete fusion first, then Ca2+ release
- Sperm extract injection into a mouse egg
- ICSI= intracytoplasmic sperm injection
- What is the sperm factor?
- The sperm factor is PLC
- Sperm extract PLC = PLC-zeta
- In vitro fertilization
- PLCzeta causes the activation of development
- PLCzeta is not species-specific
- PLCzeta phylogeny
- Evidence for the role of PLCzeta in fertilization
- How does PLCzeta work?
- Ca2+ dependence of PLC activity
- A possible feedback loop
- The dependence of calcium oscillations on InsP3
- Photo-release of caged InsP3
- The model for fertilization
- PI(4,5)P2 localization in eggs
- Mouse eggs
- Overall hypothesis
- Summary
Topics Covered
- The role of Ca2+ in activating development in eggs of all species
- Sperm egg fusion as the event that precedes the Ca2+ signal
- Evidence for a sperm factor that triggers Ca2+ release
- Discovery of PLCzeta as sperm factor in mammals
- Mechanism of Ca2+ oscillations triggered by PLCzeta
Links
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External Links
Talk Citation
Swann, K. (2020, September 18). Ca2+, fertilization and egg activation [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved December 7, 2024, from https://doi.org/10.69645/FVZC3159.Export Citation (RIS)
Publication History
Financial Disclosures
- Prof. Karl Swann has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.
Update Available
The speaker addresses developments since the publication of the original talk. We recommend listening to the associated update as well as the lecture.
- Full lecture Duration: 49:44 min
- Update Interview Duration: 11:25 min
A selection of talks on Biochemistry
Transcript
Please wait while the transcript is being prepared...
0:00
I am Karl Swann from Cardiff University.
In this lecture, I'm going to talk about the role of
calcium in the activation of development at fertilization.
0:11
At fertilization, the egg is transformed into a developing embryo.
In most species, the sperm triggers this change and
the events brought about by the sperm are referred to as activation events.
The sperm activates the egg to develop into an embryo.
One of the most dramatic examples of the change
seen at fertilization is in the sea urchin egg.
When the sperm fertilizes the egg within a minute,
you can see the formation of
a fertilization envelope around the egg that you can see in the right-hand image.
In this lecture, I shall introduce
some examples of events that have been studied in sea urchin eggs.
However, for most of the lecture,
I shall talk about what we know about fertilization in mouse egg.
The mouse egg is a useful model for mammalian fertilization in general.
In fact, we now know more about the molecular mechanisms
at fertilization in the mouse than in any other species.
1:05
This is an image of a mouse egg that has been ovulated and is ready to be fertilized.
It's the section taken both through the egg and the surrounding cumulus cells,
which are released at the same time as the oocyte from the ovary.
The DNA in this image is stained in red.
You can see the nuclei of the surrounding cumulus cells.
Within the oocyte in the center,
you can see the DNA is condensed and it's present in a metaphase plate.
That's because the oocyte is arrested at the second meiotic division at metaphase,
you can see this labeled with the yellow arrow.
What you can also see with another yellow arrow
is the product of the first meiotic division,
which is present as a first polar body.
This is a set of chromosomes that's been extruded from the first meiotic division.
The mouse egg, therefore, strictly speaking,
should always be referred to as an oocyte because it hasn't completed meiosis,
but it's often referred to an egg in the literature,
and I shall generally refer to it as an egg in this lecture.