February 11, 2016 at 02:37AM

Today I Learned: 1) Cyanobacteria (the clade of bacteria best known for their ability to photosynthesize, an early member of which is almost certainly the ancestor of modern chloroplasts) are seriously polyploid, meaning that they have multiple copies of their genome. Different species are reported to have between 3 (Synechococcus elongatus PCC 7942) and hundreds (most other strains) of copies of their chromosome. The numbers also vary quite a bit between exponential phase, when the cells are growing quickly, and stationary phase, when they're nutrient-deprived and more or less at equilibrium. During rapid growth, most species appear to have on the order of 100-300 chromosomal copies, which drops to a few dozen copies during stationary phase. Synechococcus elongatus PCC 7942 (S. elongatus) has been studied rather more carefully. During growth, S. elongatus has... several chromosomal copies (more than three, less than 10). They are spaced evenly throughout the cell and interspaced between carboxysomes, which helps make sure that when they divide, each daughter cell gets roughly the same number of chromosomes. As far as I know, we have no idea why they have so many chromosomal copies. I've been daydreaming for a while about ways to make chromosomes more error-resistant, which would help make synthetic gene circuits more robust. Ultimately, I think you have to do something like having a triplicate genome where every position is checked between the three copies and corrected to the most common version. This seems nigh impossible for many reasons, but one of those reasons was, until today, that bacteria very specifically have exactly one chromosome. Looks like I was wrong on that. Sources: http://ift.tt/23YmxOD http://ift.tt/1XkvVaU 2) ...the difference between the European Union and the Eurozone. The European Union is a... federation...? of countries (in Europe, I hope it goes without saying) which agree to a whole slew of things like open borders with other EU members states, no economic sanctions or tariffs against other EU states, and a bunch of humanitarian standards. The EU also has an elected parliament which is widely considered feckless, as well as a bureaucracy that actually wields some considerable clout internationally. The Eurozone, in contrast, is the subset of the EU which has agreed to use the euro as their standard currency and jointly manages the euro. I know, this is pretty basic stuff, but I've gotta start somewhere. 3) You can make hard cheese from goat's milk. Apparently there is one such cheese (whose name I don't know) made in Greece in very small quantities which is soaked in wine, wrapped in a mix of mud and leaves, and buried in a sandy beach to soak up sea salt for a while before it is sold. Perhaps I should check out how well the goats are treated....