Boing Boing explains Horizontal gene transfer.... not. ~ NanoThoughts 1.0

Tuesday, January 30, 2007

Boing Boing explains Horizontal gene transfer.... not.

Boing Boing: Horizontal gene transfer explains evolutionary jumps

Paul says:

Rice University study models "Horizontal Gene Transfer," a mechanism for evolution where big chunks of DNA migrate between different species via bacteria. This results in faster and more sudden evolutionary branching than what you get with the more familiar mechanisms of sexual selection or random single-point mutations caused by radiation, copying errors, etc.

Now I feel better about eating those tomatoes with the fish genes in them! (Flavr Savr)

My take:
I'm not sure who Paul is, but he gets Horizontal Gene Transfer totally wrong. Horizontal Gene Transfer (HGT) (sometimes "Lateral Gene Transfer") is predominantly an event that occurs between two prokaryotic (read: bacteria) cells. Although there is evidence for some unicellular eukaryotic HGT, multicellular HGT has yet to be observed. Bottom line, Horizontal Gene Transfer does "speed up" evolution (and at the same time, totally complicates the analysis of bacterial genomes), and it does explain some evolutionary "jumps," but it doesn't explain all of them, and certainly not ones in multicellular eukaryotes.

Also, FlavrSavr tomatoes did not have fish genes in them. In fact, no tomato that has ever reached the market has had fish genes in them. The Flavr Savr tomato contained an antisense gene for polygalacturonase. That is, it shut down the gene expression of polygalacturonase. Polygalacturonase is a pectinase which breaks down pectin. When pectin is broken down, the cell walls get mushier and the fruit gets softer. That is, it's part of the ripening process.

Furthermore, Flavr Savr tomatoes are no longer for sale in the United States and their trademark has expired.



Regal said...

Not true, my grannie would grow and sell hertomatos with fish genes. (~2min 40 sec)

Chris said...

Regal is the antithesis of Dan Quayle.

Tango said...

Hey, thanks for your corrections to the Boing Boing blog about HGT and Flavr Savr tomatos. That was bothering me, but I didn't know how to comment!

However, while HGT has not been detected between plants and/or animals, it has been detected from bacteria and viruses to both plants and animals.

Rog said...

Tango, thanks for the thanks. I intend to clarify what I meant in a future post. You are mostly right too. The main point is that bacteria do it all the time and more complex organisms really aren't, but have in the past. (but, that was mostly endosymbiotic if you ask me.)
Viruses, to me, aren't living, so don't really play the role of donor or acceptor in HGT, but instead or just vectors.
Also, I totally disagree with Deems assertion that almost all eukaryotic DNA, including humans, is the result of HGT events.
I'm also going to point out that integration of oncogenes into the human genome isn't necessarily always HGT. Simply because those same oncogenes might've come from another human.
I will clarify/expand all these points in a future post, I just wanted to get suitable references.