Dinosaurs amongst us. Crocodiles are ancient and fierce reptiles that have ruled both salt and fresh waters for 100s of
millions of years. Pictured above is the Nile crocodile found in Africa, they can grow to 6 meters long and weigh up to 700 kg. They also have a bite force more powerful than a great white shark! This modern crocodile has been around for 80 million years, so it was floating around when dinosaurs were alive. How they survived the mass extinction that wiped out the dinosaurs is still unknown!
Getting down to their genetics, interestingly the sex of a crocodile is determined after the egg has been laid in the sand. It depends on the temperature of the egg during development. Cooler temperatures of about 30°C produce females and warmer temperatures of 32°C produce males. This process is called temperature-dependent sex determination and the protein involved in this is called TRPV4. When the protein is exposed to certain temperatures it tells the cells what to do and what sex the crocodile should be.
A 2017 study by Siddiqui and others looked at crocodile proteins that fight infections and even cancers. Since crocodiles live in dirty, contaminated water and yet still live for 40 years there must be something in their genes that helps them prevent diseases. Over evolutionary time, organisms needed to come up with nifty ways to avoid dying! And they did just that by evolving this resistance system to fight off germs and cancers. This study showed that certain proteins killed off cancer cells and foreign pathogens that it came into contact with. The exact mechanism of this defence system is not understood but it is a great discovery and further research may lead to new cancer treatment plans!
Like and follow my page to read more interesting genetic stories, see ya later alligator! In a while crocodile!
Reference paper:
Siddiqui, R., S. Jeyamogan, S. M. Ali, F. Abbas, K. A. Sagathevan et al. 2017 Crocodiles and alligators: Antiamoebic and antitumor compounds of crocodiles. Experimental Parasitology. 183: 194-200.
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