Horizontal Gene Transfer: Nearer Than You Think!

[Image description: A sketch from one of the notebooks of Charles Darwin. It is a simply drawn, branched figure, with parts labeled 1, A, B, C, and D. The top is captioned “I think” and there is some cursive writing underneath and to the right of the figure. End description.]

Good evening everyone! The topic of today is going to be horizontal gene transfer (HGT), which is the transfer and uptake of genetic information from one species to a different species through means that are not standard sexual reproduction! Today’s post is inspired by David Quammen’s The Tangled Tree: A Radical New History of Life. This is a book that I have and will be working closely with for class over the next two-odd weeks.

    Scientists at two universities, the University of Haifa and the University of Tel-Aviv, have developed a technique for discerning events of HGT between closely related strains of bacteria, which they have named Near HGT. It is much easier to detect HGT in distantly related groups because the genes and base sequences are very different from each other, but difficult when the groups are highly related. Much of the existing framework at the time of the article’s publication in 2015 was based in detecting HGT between distantly related strains. I imagine doing this  would be akin to finding spots of color mixed in on a monochrome background. In a sea of greens, it would be easier to find a spot of blue or yellow. With closely related species, it might be more like trying to distinguish crimson in a sea of reds.

    Using this technique, which involves examining both the order in which the genes are organized (synteny) and constant relative mutability (the rate at which a particular gene will develop and change over time, if my understanding is correct), these scientists hope to find and study more instances of closely-related HGT. In the process of doing, they hope to bring a greater understanding of HGT, its process, implications, and its effects on organisms. As The Tangled Tree discusses, HGT has had a profound effect not only on the actual process of evolution, but our human conception of evolution and heredity as well. Though I am not yet finished with the book, I find that it is very useful for contextualizing the science and its implications within the time period of its study. I have not seen as much discussion as I would like of current applications and implications of HGT. Thankfully, this article discusses at least one: antibiotics resistance. HGT is a primary mechanism by which antibiotics resistance occurs. With more focus on what they are calling “intra-clade” HGT (which is overlooked), a greater understanding of the transfer of antibiotics resistance may be achieved. Perhaps a little lofty, but maybe one day we’d be able to slow the spread of antibiotics resistance by molecular means. Has anyone ever considered using bacteria’s proclivity towards HGT as a weapon against itself?

(In this moment, I would like to profess my undying love for the NCBI and their publicly available research information. They really are the best.)

Hoping everyone is well and sending my best wishes.

4/6/2020: A brief correction, along with my apologies. I hyperlinked the wrong research article. The appropriate link should be in its place, and my praise of the NCBI should make more sense, haha.