Hello and welcome to Autotomize This!
Seeing as this is my first blog entry I will take a moment
to talk about my inspiration for starting this blog and to explain its title.
In 2009 I began a concerted effort to understand the ecology and evolution of
the slender salamanders which live in my home state of California . These small, lungless (I will
address this in a later post), vertebrates are fully terrestrial and do not
need a pond or stream to reproduce. While they are similar in shape to lizards, with
a slender body, long tail, and four legs, they are amphibians and as such have
moist, permeable skin like their cousins the frogs. Slender salamanders share
another feature with many lizards; they can “drop” their tails when agitated.
This is a pretty good trick which goes by the name, autotomy. A slender
salamander (genus Batrachoseps) can autotomize its tail when grabbed
by a predator or when under stress.
Unlike lizards, slender salamanders regenerate their tails in
a way that makes them indistinguishable from the original tail. Rarely is any discoloration seen in regenerated salamander tails. Lizards, by contrast, often have dull or oddly colored on regenerated tails.
How salamanders do such a great job of regenerating this lost
body part with all of its nervous, muscular, and skeletal complexities?
Many salamanders are known to be extremely good at
regenerating tissue be it a tail or even a limb. Salamanders are not known to autotomize limbs but they can be lost or badly damaged by a predator or another salamander during combat. Yes, combat. Some salamanders fight, a lot.
In a recent (2013) paper in Cell Stem Cell by Sandoval-Guzman and others, Fundamental Differences in Dedifferentiation and Stem Cell Recruitment during Skeletal Muscle Regeneration in Two Salamander Species (http://dx.doi.org/10.1016/j.stem.2013.11.007) indicates that different families of salamanders regenerate tissue using different mechanisms. Their paper compares the pattern observed in Eastern newts, Family Salamandridae, to Axolotls, Family Ambystomatidae. The newts in their study used dedifferentiation of myofiber cells into stem cells (PX7-) which then regenerated the limb. Axolots on the other hand (pun intended) appear to have resident PX7+ cells in the limb tissue. When a wound occurs these are activated and proceed to regenerate the new limb.
In a recent (2013) paper in Cell Stem Cell by Sandoval-Guzman and others, Fundamental Differences in Dedifferentiation and Stem Cell Recruitment during Skeletal Muscle Regeneration in Two Salamander Species (http://dx.doi.org/10.1016/j.stem.2013.11.007) indicates that different families of salamanders regenerate tissue using different mechanisms. Their paper compares the pattern observed in Eastern newts, Family Salamandridae, to Axolotls, Family Ambystomatidae. The newts in their study used dedifferentiation of myofiber cells into stem cells (PX7-) which then regenerated the limb. Axolots on the other hand (pun intended) appear to have resident PX7+ cells in the limb tissue. When a wound occurs these are activated and proceed to regenerate the new limb.
Here’s a figure from the .html at the DOI address illustrating the different strategies:
Which of these strategies do slender salamanders (Family
Plethodontidae) use?
I have no idea!
But here’s a song about Axolots that I challenge to you
autotomize from your brain after listening:
Thanks for reading!
