Central newt in aquatic adult phase with smooth skin and noticeably finned tails.
Frog warts, lizard gizzards or eye-of-newt
Which ingredient from Granny's bag might be making a medical break-through?
Kathryn A. Kahler
A reference to Granny Clampett of the The Beverly Hillbillies seemed a bit out of place under the circumstances. I was with a group of about a dozen people on a Natural Resources Foundation of Wisconsin-sponsored night frog hike along the Wisconsin River in the Mazomanie Wildlife Area when our leader, retired DNR herp expert Bob Hay, invoked Granny's name.
"I'll bet none of you remember what Granny's favorite soup was, do you?" he asked.
Since half of the attendees were young enough to not even have heard of the popular 60's era TV show, and the rest of us were old enough not to remember what kind of soup we had for lunch that day, nobody raised their hand.
"It was eye-of-newt soup, of course," said Hay. He went on to explain the significance of the reference with a brief introduction to Wisconsin's only species of newt – the central newt, Notophthalmus viridescens louisianensis. It is one of four subspecies of the eastern newt that is found throughout the eastern United States. The newt has the extraordinary regenerative capacity of regrowing parts that are severed.
Later, as the group stood in silence in the waning light, hands cupped around our ears to better hear the singing chorus frogs and other assorted wildlife, I had plenty of time to contemplate the newt and how little I knew about it. I made a mental commitment to learn more. Now, after following up on that promise, I owe Bob Hay a big "thank you" for introducing me to an amazing little critter.
What's a newt?
The central newt – named for the part of the United States the subspecies primarily inhabits – is one of seven species of salamanders found in Wisconsin. Like frogs and toads, they are amphibians, meaning they live part of their lives in water and part on land. They reach adult size of about 2 ½ to four inches.
Unlike other salamanders, central newts are capable of metamorphosing into three distinct phases beyond the aquatic larval stage. There's the aquatic adult phase, with smooth tan-colored skin, speckled with orange and black spots and a noticeably finned tail; the terrestrial adult phase, with sandpapery dark brown back, and light belly with black specks and a narrow non-finned tail; and the much less common third phase called the red eft, or juvenile terrestrial phase. This third terrestrial phase is an orangish-red color with tiny black flecks throughout.
It seems that environmental factors, especially drought, determine which phases exist in a population. In some populations, there are no eft or terrestrial adult stages and the larvae transform directly into aquatic breeding adults. In Wisconsin, the terrestrial phases exist, but are uncommon except in drought years. If their pond begins to dry up, aquatic adults transform into the terrestrial phase and leave the water, hiding under logs and in vegetation. Their skin becomes thicker and more granular to help retain body moisture and they resorb the fin on the tail.
Efts are usually found in wooded areas up to a half mile from their breeding ponds. They scurry about the forest floor day and night, especially when the ground is moist, and seek cover under leaves and logs when it's dry. Unlike other amphibians that use camouflage to escape predation, their bright color serves as warning to predators that they should seek their meals elsewhere because the newt's skin contains tetrodotoxin, a neurotoxin. This toxin, found mostly on the newt's back, is 10 times more toxic in efts than adults.
Newts are carnivorous in all life forms, eating whatever is available that they can swallow whole, from zooplankton, insects and fish eggs, to tadpoles, leeches and their own shed skin.
The juvenile eft phase can last for months to several years, depending on the region and moisture conditions. When they reach sexual maturity, they migrate back to breeding habitat in ponds, wetlands, sloughs and quiet streams. Adults that became terrestrial follow the same migration path back to their home pond. These migrations usually occur in the fall. In Wisconsin, newts usually breed underwater in fall or winter. Come spring, the female often lays her fertile eggs singly and wraps each one in a folded leaf or piece of vegetation or deposits them in the detritus on the pond's floor. Each female lays 200 to 350 eggs, so this time-consuming process can take several weeks. Eggs hatch after about 20 to 35 days, depending on water temperature. Larvae grow for several months and then metamorphose into juveniles in one form or another.
The Granny connection
Probably the most remarkable thing about the newt is its ability to regenerate tissue. It is part of a group of vertebrates called Caudata, or salamanders, that excel at regenerating limbs, jaws, eyes and other organs. But just what is "regeneration" and how does it work? And why are newts so good at it when we humans, who we tend to think are so much more highly evolved, simply aren't?
It's all a matter of genetics and cellular biology. In the case of humans and other mammals, our cells are programmed by our DNA to follow certain patterns and "differentiate" into various tissues – skin, bone, muscle, and so forth. Our limbs and other body parts grow and develop, but once we're full-grown, they pretty much "forget" the past. A minor cut will heal, but if we lose a finger, toe or, God-forbid, a limb, new skin forms over the stump, but that's the extent of the healing. Newts, it seems, are much more flexible, especially when it comes to how they heal. Let's take, for example, what happens when one of their limbs is amputated.
As soon as the limb is cut off, skin cells quickly move to the site of amputation. Within a day, a "wound epithelium" is formed. Within this structure, cells lose their specialization and are reprogrammed, like starting over again with a clean slate. These new "de-differentiated" cells continue to divide and accumulate at the end of the stump and form what's called a "blastema," the bud of the new limb. Within about 40 days, the cells grow, elongate and re-specialize according to their original embryonic blueprint, until a new limb – complete with skin, bone, muscle and nerves – is formed. The new identical limb is complete in about three months.
Here's where Granny comes in. Granny was a backwoods mountain doctor, keeping her medical bag supplied with ingredients like frog warts, lizard gizzards and eye-of-newt. While it's unclear what role the amphibian body parts played in her concoctions, perhaps she was closer to science than wizardry than we thought. Recent breakthroughs in the field of regenerative medicine cite newts and other salamanders as sources of secrets that might be used to treat human ailments from brain and heart diseases to helping war veterans regenerate limbs and repair spinal cords.
In a Science Daily article from April 2007, project leader Dennis A. Steindler of the University of Florida's McKnight Brain Institute, said a $12 million project called the Regeneration Project would "focus on unlocking the mysteries in living, simple organisms that sustain successful tissue and organ regeneration following injury and disease, and then applying this knowledge toward encouraging repair in the more complex human, where regeneration is not so simple."
Even more recently, a group blog from the Consortium for Evolutionary Studies at California State University at Fresno, called "Darwin's Bulldogs" suggests that regenerative medicine may be more beneficial than organ transplants or even stem cell therapy "because the cells involved in dedifferentiation come from the patient going through treatment. By using one's own cells there is no risk of initiating an immune response and no chance of rejection. In addition, ethicists might be more favorable to this type of regenerative medicine as opposed to embryonic stem cells."
Perhaps Granny was way ahead of her time. In an episode in season six called "Rags to Riches," Mr. Drysdale, the Clampett's banker and neighbor, is knocked out in a fracas with his wife and Granny gravely declares that none of her usual remedies will do the trick. So she begins arrangements for the first-ever head transplant. Then again, maybe that's a bit of a stretch.
Kathryn A. Kahler is a staff writer for Wisconsin Natural Resources magazine. Thanks to the Natural Resources Foundation for inviting her on the field trip.