Tip:
Highlight text to annotate it
X
VO: How can some animals regenerate body parts following injury? Why can't humans do the
same thing? Four scientists in the University of Kentucky Department of Biology are undertaking
basic scientific research to begin to answer these questions. Humans carry in our DNA a
genetic legacy that we share with other vertebrates. Scientists hope to one day uncover healing
abilities that may lie hidden in our own genome.
VO: To study cell regeneration in the eye, Ann Moriss's vertebrate of choice is Zebrafish,
a minnow-like freshwater fish. Ann Morris: when something happens to our
neurons, either in your brain or in your retina, if the neurons die they can't be replaced.
Now unlike mammals, zebrafish are able to regenerate neurons after injury or disease.
And so we want to understand what are the genes that you need to replace those neurons,
how is it that those neurons are able to be remade. And if we can understand that, then
we may be able to inform efforts to try to develop therapeutic approaches to treat retinal
degenerative diseases in humans. When you're remaking neurons what you're doing
is your taking a tissue that is already present, that's a circuit if you want to make that
analogy, that's already existing and you're asking for cells to be remade and somehow
integrate themselves into an already existing circuit. So it's not just a question of remaking
the cells, but also getting them to connect up to the right partners and find, and migrate
to the right position and find the proper place. And so those are sort of all the things
that we are gonna have to figure out.
VO: Randal Voss is sequencing the genome of salamanders. Though we share many of the same
genes, the salamander genome is massive compared to our own—about 10 times as large. Voss's
research focuses on axolotls—salamanders with amazing regenerative ability.
Randal Voss: It's hard to find a body part they can't regenerate: the limbs, the tail,
the spinal cord, the eye, and in some species, the lens, even half of their brain has been
shown to regenerate. One thing that we have been doing for the
last four years is measuring the abundance of gene expression transcripts from genes
during the course of limb regeneration. Over a time course, collect the tissue, isolate
RNA from the tissue, then use that RNA and hybridize it to a gene chip, which allows
you to estimate the expression of 20,000 genes at one time. You do that over and over and
over again. The last four years we've collected eight million estimates of gene expression
from that approach. We're building a model for how genes are turned on and how turned
off over very small time scales so that we can have this blueprint to move forward with.
VO: Voss's partner in salamander gene sequencing is Jeramiah Smith. Smith also brings expertise
in another species: sea lamprey. Jeramiah Smith: We know that lampreys, for
example, can regenerate their spinal cord. They'll repair their spinal cord, and in five
weeks the animal can swim perfectly. We think that this unique biology of lamprey can allow
us a handle into identifying those specific cell types that are maybe set aside that permit
regeneration.
We know these animals heal and we'd like to figure out how so we can heal better. You
can think of this as several baby steps, too, in terms of identifying some of the factors
that allow cells to create these special undifferentiated cell types that promote regeneration.
VO: Five years ago, Ashley Seifert, whose research was focused on skin regeneration
in salamanders began to look at another remarkable species: African spiny mice.
Ashley Seifert: what's phenomenal is that they're able to regenerate complex tissue
structures. So they can regenerate pieces of their skin that includes hair follicles
and sebaceous glands, which are associated with the underlying dermis, the structural
component of the skin which gives it strength. And then in the ears, amazingly, they can
regenerate cartilage. If you talk to an orthopedic surgeon he'll tell you that would be a huge
advance if we could figure out how to regenerate cartilage in a mammal because we don't have
any way to do that right now. We punch a hole through the ear here and then
we use that as our model to watch regeneration. We reconstruct that process through these
pictures of the tissue as it regenerates. VO: Together, these scientists make up the
core of an unofficial regeneration "cluster," an emerging area of strength for UK.
Randal Voss: Within just four or so years, we've brought in all these really good, young
scientists that work on a similar problem. I can go talk to Ann about the eye. I can
go talk to Ashley about the limb. I'm working really closely with Jeramiah on building a
representation of what the genome looks like.
Jeramiah Smith: The great thing about the group is we're not really invested strongly
in any single system. We're invested in cross-talking between systems.
Ann Morris: That's something that's really rare across the country, to have that many
people clustered in one department who are interested in studying regeneration. And I
think it's enormously beneficial, especially for our graduate students to have these kinds
of interactions with multiple investigators studying this really interesting biological
question.