April 22 2016 at 02:24AM

Today I Learned: 1) Here's a fun paleontology story, courtesy of Mengsha Gong. There are a lot of fossils of giant clams from the Mesozoic era. Berkeley has one such specimen, which happened to have a pair of holes in it. For a while, it was simply assumed that it had been crushed or fallen on by a rock or something similar. Then someone realized that it looked an awful lot like a pair of tooth holes, and there happened to be another fish with teeth just the right distance apart from the same time period.... Another fun anecdote: check out this thing. What do you think it is? http://ift.tt/23NhYsS Did you guess a pair of shrimp? That's what it looks like to me. The trouble is, they always come in pairs. That's because they belong to this guy, Anomalocaris (who was, by the way, about human-sized. Have a nightmare.): http://ift.tt/1SV39Js 2) The "turnover number" of an enzyme (or other catalyst) is the number of reactions the catalyst will perform, on average, before degrading, mis-reacting, or otherwise becoming unable to do its thing. Typical turnover numbers for enzymes are between 10 (at the *very* lowest) and several tens of thousands. Typical turnover numbers for man-made catalysts are less than 50. Unless they're manmade enzyme catalysts -- go Bioengineering! Kudos to Anders Knight on this one. 3) Cajil Bodies are sub-organelles of the nucleus, and are basically clumps of protein about the size of a smallish bacteria. Cajil bodies are involved in RNA processing, and are mostly found in cells that are either actively dividing (gametes, tumors) or doing a lot of metabolizing (neurons), presumably because these cells are pumping out tons of RNA to get processed. Relatedly, I learned that the nucleolis isn't really a separate compartment of the nucleus -- it's just a very dense cluster of coiled chromosome and its associated machinery, along with a bunch of nuclear ribosomes. Though given how dense that bit of the nucleus is, it might be wise to consider it as a separate compartment for many purposes.