Why is the Rotifer Full of Foreign Genes? An MBL Team Investigates

A decade ago, the MBL’s Irina Arkhipova and colleagues made the curious discovery that the bdelloid rotifer – a microscopic animal – has an abundance of foreign genes in its genome that it has acquired from bacteria, fungi, and plants.

Typically, genes are transmitted vertically from parent to offspring, while in some cases organisms can acquire genes horizontally from other individuals in their environment. Horizontal gene transfer is common in bacteria, but it is rarely seen in eukaryotes (animals, plants, fungi, algae, and protists).

Arkhipova, a scientist in the Bay Paul Center, has been puzzling out how this massive horizontal gene transfer (HGT) in rotifers occurred, and how the genes are functioning in the animal once acquired. She recently received a grant from the National Institutes of Health to continue these investigations, including her identification of non-canonical DNA modifications brought about by genes of bacterial origin, and of novel, giant transposable elements in the rotifer genome that may have participated in the HGT.

Her research aims to uncover the complex evolutionary history of foreign gene acquisition and diversification in this exceptional animal, and to better understand how the barriers preventing such acquisition in most eukaryotes can occasionally be broken in selected branches of the tree of life.