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Hello. I'm Jonathan Ewbank.
Researcher. Ciml in Marseille, France.
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Today, I'm going to be talking in some detail about the interaction
between C. elegans and a specific fungal pathogen.
Before you watch this lecture,
you may want to see the one that I recorded in 2011,
which gives some background information about C.
elegans and about its interaction with various pathogens.
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Organisms throughout evolution have needed active homeostatic mechanisms that
maintain stable internal environment in the face of external variations.
Many of these environmental changes concern abiotic parameters like
ph or temperature that are the same now as they were when life first evolved.
Perhaps, not surprisingly, the molecular mechanisms,
that are deployed, for example,
to counter heat shock, are highly conserved.
Pathogens represent another challenge to organismal homeostasis.
But in this case, the challenge is not static.
Pathogens can evolve rapidly.
As a consequence, post defense mechanisms need to adapt to a constantly evolving threat.
Along each branch of the phylogenetic tree,
species have evolved their own specialized forms of defense.
For example, adaptive immunity is only found in jawed vertebrates.
We have chosen to look at host defenses in the nematode Caenorhabditis elegans,
a widely used model in biology.
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C. elegans diverged from mammals hundreds of millions of years ago.
Studying its interactions with pathogens promises to
give insights into origins and evolution of host defenses.
C. elegans is well suited to investigations at the molecular,
cellular, and organismal level.
So it can help us, not only understand how an immune system works,
but also how it functions in the context of the physiology of a whole organism.
We chose C. elegans for many reasons,
but principally because it is a very powerful genetic model.
There's a strong research community that collectively
has generated a broad set of experimental tools and resources.
Further, it represents a branch of the evolutionary tree that had not been
explored and so is complementary to other models used to investigate innate immunity.
