http://www.pnas.org/content/suppl/2013/07/08/1306113110.DCSupplemental/sm03.wmv
Long read for your weekend.
The movie above (via this article in PNAS) is a bunch of yeast defective in reproduction--they stay chained together to their offspring as opposed to budding off completely and becoming individual cells. (Normal yeast look like this.)
The green fluorescence in each video is tagging literal sex-change gene; yeast about to split express it to change their sex. Correct, there are male and female yeast.
As you may (not) notice, the green expression in the above video differs from the normal expression. But how? Unless you're a beer maker with a penchant for microscopy, you probably couldn't figure it out. Pretty cool though: the gene is strictly expressed in the mother yeast before mitosis. When the two daughter yeast (what each half of the mother yeast is called) form, the expression is strictly cut off.
So what's the upshot of this entire study? In the defective yeast, the expression spills over into the daughter cells (those flares of green in the video, which occur while the yeast is still connected). Basically, the yeast is all:
Investigators took a look into this and realized that even though the expression mechanisms were replicated (which is usually where "acquired traits" like weight, happiness, dyed hair color, etc get thrown into the garbage and not passed on), the pattern persisted on the mechanisms. Specifically, modifications to the proteins that DNA wraps around like a spool of thread were passed on to the daughters.
This complex topic is called epigenetics--outside genetics. It's been plaguing science students since 1999 (or whenever it was discovered) and making their neatly learned paradigms of inheritance INCREDIBLY MESSY. This is another cool study in showing how you can get traits your parents had.
