June 18, 2016 at 04:33AM

Today I Learned: 1) Termite mounds can be extremely old. One abandoned mound in the Democratic Republic of the Congo was radio-carbon-dated at about 2200 years old. Several other, smaller mounds nearby measured in the hundreds of years old. This is way, way longer than a single colony lives -- termite queens only live a few decades. It's suspected that mounds are built up over successive generations, through multiple rounds of abandonment and recolonization. This fact brought to you by Kevin Cherry. 2) The Lac repressor protein in E. coli is notable for only being expressed at a level of about 10 copies per cell. Today I found a chart (this one, to be precise: http://ift.tt/1Yyqyr7) of per-cell copy numbers and numbers of binding sites for various DNA-binding proteins known as of 1998. If that chart is to be believed, LacI is a rather unusual repressor. For one thing, it's the only repressor with typical copy number of less than about 100. For another thing, it has extremely few binding sites -- LacI has between 1 and 5 predicted binding sites, depending on how threshold binding sites, while most binding proteins have hundreds to thousands of binding sites. 3) A couple of interesting details of ballroom competitions. The way most competitions work is that somewhere between several and a bunch of dance pairs all dance at once on a single dance floor, and several judges watch the whole thing and give marks to the various pairs. One of the more important goals of ballroom, then, is to get the attention of the judges, since you're literally competing with the other dance pairs for physical and visual space. There is, for example, a careful balance to be struck when walking out onto the dance floor and claiming space -- you and your partner want to collectively take up as much space as possible, so you will stand out and have room to maneuver, but if you stand too far apart you won't look like a cohesive pair. Another interesting thing that can happen -- sometimes a ballroom dance pair will move into a corner for one reason or another. If they time it badly (or other teams time themselves well), they can end up pinned in the corner by other teams, making it awfully difficult to continue dancing.... Ballroom dance details courtesy of Mengsha Gong.