Scientists Sequence Genome of Endangered Chinese Alligator

Sequencing genomes has become a priority for scientists across the globe. They've uncovering startling new information about the different species that inhabit our planet. Now, researchers have completed the genome sequencing and analysis of a new animal: the endangered Chinese alligator. The new research could provide an explanation as to how terrestrial-style reptiles adapted to aquatic environments.

The Chinese alligator is officially known as Alligator sinensis. With less than 100 of these animals in the wild, the alligator is critically endangered. Officials are, however, making strides to help protect this species--about 10,000 individuals remain captive in Zhejiang and Anhui Provinces. In addition, scientists are attempting to learn more about this creature in order to find out exactly what makes it uniquely suited for living life on both water and land. This, in turn, could help with the preservation of the species.

In order to learn more about the Chinese alligator, the researchers collected samples from the Changxing Yinjiabian Chinese Alligator Nature Reserve. They then sequenced the alligator genome using a whole-genome shotgun strategy. The resulting data yielded a draft sequence of Chinese alligator with the size of 2.3 Gb and a total of 22,200 genes.

So what did this genome tell the researchers? The scientists found out why exactly the Chinese alligator can hold its breath underwater for long periods of time. It turns out that there's a duplication of the bicarbonate-binding hemoglobin gene, which positively selects energy metabolism. In addition, the scientists found results that pointed to co-evolution of multiple systems that were specific to the "back-to-the-water" transition of the alligator.

That's not the only thing that the scientists discovered, though. They also found that there's an absence of sex chromosomes in the alligator. Instead, the Chinese alligator exhibits temperature-dependent sex determination (TSD). This makes the alligator the first TSD species whose genome has been sequenced, which will have great implications in resolving sex chromosome evolution.

"The accomplishment of the Chinese alligator genome is significant for understanding its adaptation for both aquatic and terrestrial environments and, more importantly, for the conservation of such an endangered species," said Shengkai Pan, project manager of the new research, in a news release.

The findings are published in the journal Cell Research.