Expandable Organs Allow Python to Digest Huge Meals
The first full study of a snake's genome has revealed the Burmese python to be one of the most evolutionarily advanced creatures on Earth, international researchers said Monday.
The findings shed new light on how these southeast Asian natives have survived and thrived, and may offer new inroads to treating human diseases, said the report in the Proceedings of the National Academy of Sciences.
"Snakes have basically undergone incredible changes at all levels of their biology, from the physiological to the molecular," principal investigator David Pollock said.
These changes took place in functionally important ways over the past five to 30 million years, allowing the slithering creatures to adapt like no other, said Pollock, associate professor of biochemistry and molecular genetics at the University of Colorado School of Medicine.
Of particular interest to scientists is just how the Burmese python -- which can grow to 20 feet (seven meters) or larger -- is able to eat creatures as large as the snake itself.
Not only can its head and jaw open wide enough to envelope a meal the size of a deer, the snake's organs supersize themselves and go into overdrive in order to speedily digest the animal before it rots.
In the space of a day or two, the snake's heart, small intestine, liver and kidneys increase in size, ranging from a third larger than before to double their pre-feast size.
Once the meal is digested, the organs return to normal.
An analysis of the Burmese python's genome suggests that a complex interplay between gene expression, protein adaptation and changes in the genome structure allows these snakes to do what others with the same genes cannot.
"You think of being a tube as being really simple, right?" said Pollock.
"But, in fact that makes life a lot harder, and they have got all sorts of adaptations in a sense that are very unique to make up for that."
Snakes went through a phase went they lived underground. During this phase of their evolution, their skulls elongated, their lung capacity went down in response to the lower amount of oxygen available, and their eyesight was diminished, he explained.
When they moved above ground, they developed the capacity to dramatically shift their metabolism, from low to high, in order to consume what might have been a rare meal.
"Their morphology has changed, their physiology, their metabolism, and their genes, their genomes have changed to match. So that is a pretty neat finding," said Pollock.
Understanding how the snake's body orchestrates such major changes in key organs could offer a new understanding of the mechanisms behind human conditions such as organ failure, ulcers, metabolic disorders and more, said co-author Stephen Secor.
"With its genome in hand, we can now explore the many untapped molecular mechanisms it uses to dramatically increase metabolic rate, to shut down acid production, to improve intestinal function, and to rapidly increase the size of its heart, intestine, pancreas, liver, and kidneys," said Secor, associate professor of biological sciences at the University of Alabama.
The Burmese python genome study was led by Todd Castoe, an assistant professor of biology at The University of Texas at Arlington College of Science, and included 38 co-authors from four countries.
It is described in PNAS along with the genome of the king cobra.
"We'd like to know how the snake uses genes we all have to do things that no other vertebrates can do," said Castoe.