Scientists sequence the genomes of six bat species for clues to their unique features

Myotis myotis (Greater mouse-eared bat), Credit: Olivier Farcy.

Bats are the only flying mammals in the animal kingdom — but that’s not all they’re known for. Bats have a number of quite extreme adaptations, such as echolocation, highly sensitive sensory perception, significant longevity for their size, resistance to cancer, and exceptional immunity to viral infections. In fact, the coronavirus that has caused the world to grind to a halt is believed to have evolved inside bats, before jumping into humans.

No doubt, bats are amazing creatures. Now, for the first time, researchers have sequenced the raw genetic material that contains the instructions for bats’ unique, superpower-like adaptations.

“Given these exquisite bat genomes, we can now better understand how bats tolerate viruses, slow down aging, and have evolved flight and echolocation. These genomes are the tools needed to identify the genetic solutions evolved in bats that ultimately could be harnessed to alleviate human aging and disease,” Emma Teeling, senior author of the new study and a researcher at the University College Dublin, said in a statement.

Teeling and colleagues affiliated with Bat1k, a global consortium of researchers on a mission to sequence the genomes of every one of the 14,210 living bat species, published a study today in which they describe the genomes of six bat species.

The genomes were highly accurately analyzed with state-of-the-art sequencing technology and are about 10 times more complete than any other bat genome published in the past.

“Using the latest DNA sequencing technologies and new computing methods for such data, we have 96-99% of each bat genome in chromosome level reconstructions – an unprecedented quality akin to for example the current human genome reference which is the result of over a decade of intensive “finishing” efforts. As such, these bat genomes provide a superb foundation for experimentation and evolutionary studies of bats’ fascinating abilities and physiological properties” Eugene Myers, senior author of the study and Director of Max Planck Institute of Molecular Cell Biology and Genetics, and the Center for Systems Biology, said in a statement.

The first six bat genomes that were sequenced part of the Bat1K global genome consortium belonged to the greater horseshoe bat (Rhinolophus ferrumequinum), the Egyptian fruit bat (Rousettus aegyptiacus), the pale spear-nosed bat (Phyllostomus discolor), the greater mouse-eared bat (Myotis myotis), the Kuhl’s pipistrelle (Pipistrellus kuhlii) and the velvety free-tailed bat (Molossus molossus). 

Their genetic blueprints were compared to 42 other mammals, which enabled the researchers to pinpoint the position of bats on the mammalian tree of life.

Rhinolophus ferrumequinum (Greater horseshoe bat), Credit: Daniel Whitby.

Due to their many unique quirks, the question of where bats fit in on the tree of life has always been unresolved. But using novel phylogenetic methods and molecular datasets, the evidence suggests that bats are most closely related to Ferreuungulata — a group of mammals that includes carnivores like dogs, cats, and seals, as well as pangolins, whales, and hoofed mammals. Not a very narrow definition seeing how bats and cows are on the same roster, but as more bat genomes are sequenced their taxonomy can be refined further.

The side-to-side comparison of different mammalian genomes also helped tease apart adaptations that are unique to bats through the loss and gain of certain genes.

For instance, the genes that enable bats’ famous echolocation were selected for in the ancestral branch of bats, suggesting this is an ancient trait in this group of mammals.

There was also evidence of gene loss and gain involved in immunity, particularly the expression of antiviral APOBEC3 genes. This may explain why bats have exceptional immunity that makes them extremely tolerant to viral infections.

In this day and age, understanding the molecular mechanisms that allow bats to withstand coronaviruses may lead to new approaches, therapies, and vaccines meant to increase human survivability in the face of COVID-19.

“Having such complete genomes allowed us to identify regulatory regions that control gene expression that are unique to bats. Importantly we were able to validate unique bat microRNAs in the lab to show their consequences for gene regulation. In the future we can use these genomes to understand how regulatory regions and epigenomics contributed to the extraordinary adaptations we see in bats.” Sonja Vernes, Co-Founding Director Bat 1K, Max Planck Institute for Psycholinguistics, Nijmegen, Senior Author

Although the researchers sequenced the genomes of only six bats, they’ve already learned quite a lot. However, this is merely the beginning — there are still more than 1,400 known bat species to go.

The findings appeared in the journal Nature.

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