Horizontal gene transfer from two bacterial genomes into one animal nucleus

For the past two weeks, the science of horizontal gene transfer (exchange of DNA between unrelated organisms such as between microbes and animals) has been a source of scholarly debate, specifically for the case of tardigrades (see Atlantic article). Our latest lab publication in PeerJ (an affordable, transparent, and open access journal) by first author @DNAdiva87 will not cause such a ruckus. Based on DNA sequencing, analysis, and importantly staining of the bacterial inserts in the animal genome, we show for the first time transfer of hundreds of genes from two different Wolbachia bacteria into one host grasshopper genome. Graphical and text abstract are enclosed below. It is also, as of today, featured at the top of the PeerJ journal site.

This work could not have been done without the talents of a great scientist like Lisa and our colleagues in Spain. They and the work were featured in a podcast for "This Week in Microbiology" on 12.17.15. You can check it out here from time 40:48 - 54:25.

Hybrid zones and the consequences of hybridization have contributed greatly to our understanding of evolutionary processes. Hybrid zones also provide valuable insight into the dynamics of symbiosis since each subspecies or species brings its unique microbial symbionts, including germline bacteria such as Wolbachia, to the hybrid zone. Here, we investigate a natural hybrid zone of two subspecies of the meadow grasshopper Chorthippus parallelus in the Pyrenees Mountains. We set out to test whether co-infections of B and F Wolbachia in hybrid grasshoppers enabled horizontal transfer of phage WO, similar to the numerous examples of phage WO transfer between A and B Wolbachia co-infections. While we found no evidence for transfer between the divergent co-infections, we discovered horizontal transfer of at least three phage WO haplotypes to the grasshopper genome. Subsequent genome sequencing of uninfected grasshoppers uncovered the first evidence for two discrete Wolbachiasupergroups (B and F) contributing at least 448 kb and 144 kb of DNA, respectively, into the host nuclear genome. Fluorescent in situ hybridization verified the presence of Wolbachia DNA in C. parallelus chromosomes and revealed that some inserts are subspecies-specific while others are present in both subspecies. We discuss our findings in light of symbiont dynamics in an animal hybrid zone.

Cite this as

Funkhouser-Jones LJ, Sehnert SR, Martínez-Rodríguez P, Toribio-Fernández R, Pita M, Bella JL, Bordenstein SR. (2015) Wolbachia co-infection in a hybrid zone: discovery of horizontal gene transfers from two Wolbachia supergroups into an animal genome. PeerJ 3:e1479 https://doi.org/10.7717/peerj.1479