WEIRD COOL EXPERIMENT ALERT!
For some reason, I have no idea why (Im sure they have a good reason– obesity research, farming research), scientists were playing a selection game with chickens.
Select the skinniest chickens. Breed them. Select the skinniest chickens. Repeat.
Select the fattest chickens. Breed them. Select the fattest chickens. Repeat.
Keep doing that until you get a population of skinny chickies and another population of fat chickies. How are these two populations different?
Well, there was clearly a behavioral difference between these two. Fat chickens were compulsive eaters, while 2-20% of the skinny chickens, even if they were given all the food they wanted, died from anorexia.
So scientists did what any rational person would do: They ground up the chicken brains and looked for gene expression differences.
Guess what one of the big differences was.
Youll never guess.
Skinny chickens? They had increased expression and increased copy numbers of a still active ERV in chickens, avian leukosis virus subgroup-E.
At first, this didnt totally surprise me. The starving chickens are under stress. Their DNA is not being epigenetically modified properly, because the food isnt there to get the parts the cell needs to do it. No epigenetic silencing, ERVs are free to be active. Their host is under stress. They need to jump ship.
So, active ERVs in skinny chickens is an effect of skinniness, not a cause… BUT, the researchers looked at other families of ERVs in chickens. Only the ALV-E ERVs changed their expression/copy numbers! Not other ERVs, not other subtypes of ALV (A/B/C/D/J). If this was a global effect of epigenetic modifications, all the ERVs would have started acting up, right?
No idea what this means yet. Dont run around telling your friends “Dont eat your veggies so your ERVs act up and you can get all skinny!!!” Just file it under ‘weird cool experiment’ for now 🙂