Researchers from the University of Georgia found that genomes of snake species such as king cobra, boa constrictor and Burmese phyton were interestingly embedded with blueprints for the development of limbs. As snakes are the best examples that movement can be possible even without arms and legs, this finding came as a surprise for the experts.
According to Douglas Menke, senior author of the study and an assistant professor of genetics in university's Franklin College of Arts and Sciences, being legless has not always been the case for snakes. More than 100 million years ago, the snakes have evolved to be limbless. Before snakes have developed into the modern-day slithery animals that most people now know, several generations of species have passed. Since snakes developed to be limbless through time, experts expect that the DNA associated with limb formation would just grow obsolete or be transformed into another physiological structure; however, a new study had proven that it was not exactly how it turned out. With this, the researchers wanted to know the reason why snakes have kept the DNA that looks purposeless for them.
Little did the experts know that the genetic materials behind limb formation are the very same tools that control the development of the external genitalia. This is probably the reason why the snakes have not let go of the genome for so long.
In the experiment that detected this phenomena, the researchers including Carlos Infante, a postdoctoral researcher, studied the particular locations of enhancers, which are the noncoding DNA that commands gene expression, controlling when genes should be activated during the embryonic stages.
The experts then monitored the patterns of activity of these enhancers in the limbs and genitalia of mice and lizard embryos. It turns out that the same enhancers were turned on during the development of these structures in both subjects.
To establish a stronger back-up evidence, the scientists also engineered a study mice to lack one of the enhancers. When the mice came out, it was found to have physical deficits in its legs and genitalia. In snakes, this enhancer solely works during genital development.
"What this means is that much of the genetic circuitry that controls the development of limbs is also important for the formation of genitalia," said Menke."And we think that's why snakes still have the genetic blueprints for limb development in their genome."
This new study does not only prove to have implications in snake research but in human studies as well. As some genetic human disorders involve the limb and genitalia development problems, such as in hand-foot-genital syndrome, which is caused by a protein-coding gene mutation, Menke said the possibility that non-coding gene defects may also be suggested as per their recent study.
In the future, Menke said he will study the degree of impact that non-coding genes have in terms of forming different genital shapes, as seen in nature.
The study was published in the journal Developmental Cell.
