UpDate - Vol. 12, No. 25, Page 14
March 25, 1993
Project gets unexpected help from iguana

     It was the night of the iguana recently at Marji Gravett's home in
Hockessin began when her pet Rex (renamed Rexana after the fact) began
laying eggs. Now, these eggs will be part of an undergraduate research
project.
     She had failed to recognize signs of impending motherhood: Rexana had
been looking bloated, while at the same time, off her feed for three weeks,
and she kept scraping at the bottom of the 90-gallon aquarium she calls
home.
     When the first egg appeared from her supposedly male pet, Gravett was
dumbfounded.
     For posterity, she videotaped the entire event, capturing the laying
of the total of 39 eggs.
     While laying her eggs, Rexana's orange spots grew brighter, but
afterward, she returned to the green of health for an iguana. And, she
began eating voraciously again, including a few of the eggs that had been
left in the aquarium.
     Not really knowing what to do with the eggs, Gravett carefully wrapped
them and put them in the freezer.
     News of the unexpected event reached the Hockessin Community News,
which ran a picture and story about Rexana, mentioning the fact that the
eggs were in the freezer if anyone was interested in them.
     The article caught the eye of another Hockessin resident, Virginia
Abrams, who works as a research assistant with Harold White, professor of
chemistry and biochemistry at the University. One of their projects focuses
on the biochemical evolution of reptiles and birds through a study of
RfBP-a riboflavin-binding protein found in their eggs.
     "It was fortuitous," Abrams said. "We have analyzed RfBP in chicken,
alligator, painted turtle and Indian python eggs, but have not had access
to lizard eggs.
     "Furthermore, Marji had properly preserved them so they can be used
for analysis for an undergraduate research project."
     The eggs resemble small, white, round pfeffernuss cookies, Abrams
said, and instead of a hard shell, have a soft, leathery surface.
     Abrams said that she hopes the eggs have not been fertilized. Some
species, such as female snapping turtles, can store sperm for five years
before fertilization occurs, she said.
     "There is a lot we do not know about eggs. What we do know is amazing
and fascinating," Abrams said.
     For example, outside temperature determines the sex of alligator eggs.
Some turtle eggs, on the other hand, will not hatch until a certain
temperature is reached and can remain unhatched for a year.
     Some snakes lay eggs, and other snakes give live birth to their
offspring. Some species eat their eggs and their young, while others, such
as alligators, are protective of their nests.
     Sharing freezer space in White's lab are eggs from a tuatara, an
ancient species in New Zealand, that is almost a living fossil, White said.
     White and Abrams are excited about these newest additions to their egg
collection, but White said what he really would like are some duckbill
platypus eggs. Some were available, but they were improperly cared for
before delivery.
                                        -Sue Swyers Moncure