Resurrection of DNA Function In Vivo from an Extinct Genome

Andrew J. Pask,Marilyn B. Renfree,Richard R. Behringer

doi:10.1371/journal.pone.0002240

Andrew J. Pask, Marilyn B. Renfree + Show 1 more

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https://doi.org/10.1371/journal.pone.0002240

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Abstract

There is a burgeoning repository of information available from ancient DNA that can be used to understand how genomes have evolved and to determine the genetic features that defined a particular species. To assess the functional consequences of changes to a genome, a variety of methods are needed to examine extinct DNA function. We isolated a transcriptional enhancer element from the genome of an extinct marsupial, the Tasmanian tiger (Thylacinus cynocephalus or thylacine), obtained from 100 year-old ethanol-fixed tissues from museum collections. We then examined the function of the enhancer in vivo. Using a transgenic approach, it was possible to resurrect DNA function in transgenic mice. The results demonstrate that the thylacine Col2A1 enhancer directed chondrocyte-specific expression in this extinct mammalian species in the same way as its orthologue does in mice. While other studies have examined extinct coding DNA function in vitro, this is the first example of the restoration of extinct non-coding DNA and examination of its function in vivo. Our method using transgenesis can be used to explore the function of regulatory and protein-coding sequences obtained from any extinct species in an in vivo model system, providing important insights into gene evolution and diversity.

Highlights

Extant species represent less than 1% of the genetic diversity that has existed in the animal kingdom [1]
We chose to isolate the well-characterised transcriptional enhancer element of the proa1(II) collagen (Col2a1) gene [15,16,17]. This element was chosen because it is relatively conserved among mammals and directs chondrocyte-specific expression in the mouse [15,17]
While the intensity of the reporter gene expression seen in the transgenic fetuses varied, the sites of expression did not

Summary

Introduction

Extant species represent less than 1% of the genetic diversity that has existed in the animal kingdom [1]. Extinction rates are increasing at an alarming rate, especially of mammals [2,3] Many efforts, such as that of the Frozen Zoo (San Diego Zoological Society Conservation and Research for Endangered Species) are working to cryo-archive cell and tissue resources from a diverse range of threatened species, to protect their genetic information. For those species that have already become extinct, access to their genetic biodiversity may not be completely lost. Some thylacine pouch young and adult tissues were preserved in alcohol in several museum collections around the world (Figure 1b)

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Conclusion