Scientists Discover Unusual New Type of Cell

Scientists studying Burmese pythons have identified a previously unknown type of intestinal cell that plays a key role in breaking down and absorbing the bones of their prey, the Journal of Experimental Biology reported.

While most carnivores tend to eat only soft tissue and either avoid bones or pass them without digesting them, many snakes and reptiles consume their prey whole, skeleton included. Until now, the specific biological processes that allow them to digest bones so efficiently have remained unclear.

It is well known that snakes fed a diet lacking bones can develop calcium deficiencies, which shows that skeletal material is essential for their health. At the same time, fully absorbing an entire skeleton presents another challenge: the potential for excessive calcium to flood their bloodstream.

“We wanted to identify how they were able to process and limit this huge absorption of calcium through the intestinal wall,” says Dr Jehan-Hervé Lignot, a Professor at the University of Montpellier.

Dr Lignot and his team analysed the enterocytes, or intestinal lining cells, of Burmese pythons (Python bivittatus) using both light and electron microscopy alongside blood calcium and hormone measurements. This study revealed the presence of a new type of cell along the intestine that is involved in the production of large particles made from calcium, phosphorus, and iron.

“A morphological analysis of the python epithelium revealed specific particles that I’d never seen in other vertebrates,” says Dr Lignot. These particles were found inside the internal “crypt” of specialised cells that differed from traditional intestinal cells. “Unlike normal absorbing enterocytes, these cells are very narrow, have short microvilli, and have an apical fold that forms a crypt,” adds Dr Lignot.

To assess the function of these new cells, the intestinal cells of pythons were analysed after they had been fed on three different diets: a normal diet of whole rodents, a low-calcium diet of “boneless prey,” and a calcium-rich diet of boneless rodents supplemented with injections of calcium.

The researchers found that when fed with boneless prey, these calcium and phosphorus-rich particles were not produced, but when fed with either a whole rodent or the calcium-supplemented diet, the cell’s crypt filled with large particles of calcium, phosphorus, and iron. No bone fragments were found in the python’s faeces, confirming that skeletons were always entirely dissolved inside the body.

This new specialised bone-digesting cell has now been identified in several python and boa species, as well as the Gila monster, a venomous lizard native to the Southwestern United States and Mexico.

However, bone-filled diets aren’t limited to reptiles and there are many other carnivores that eat bony animals whole. “Marine predators that eat bony fish or aquatic mammals must face the same problem,” says Dr Lignot. “Birds that eat mostly bones, such as the bearded vulture, would be fascinating candidates too.”

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