So Eppendork was sitting contemplating her bejewelled navel, as you do on a slow Monday morning, when she came across a pretty cool paper. And now I think the mechanisms behind diphasic flagella in Salmonella are pretty fucking cool. I mean the switch mechanism is just that hot. So here’s how it goes – Salmonella have two flagellin loci in the genome – not terribly unusual for bacteria – kinda cool not that that interesting – the interesting bit comes in the form of the switch that allows the Salmonella cell to express only one form of flagellin subunit either fliC or fljB (the genes are only expressed alternately, such that you can have only one form of flagellin - no mixies going on, or so they thought).
As far as I can tell fliC is transcribed constitutively by the cell – which is fine if that’s all it ever does then it will only have a phase 1 flagellin – however if the fljB is thrown – well it all gets interesting (if it is you get a phase 2 flagellin). The flagellin 'switch' are two proteins Hin and Fis, working in conjunction with each other to cause the inversion of the the fljB/fljA operon, which is normally inverted. Normally this operon remains dormant and isn’t expressed, but invert it and bobs your uncle you have a working operon. And this is where it gets cool – fljA is expressed, it then latches on to the constituitively expressed fliC rendering it unable to be translated! It never gets translated so fljA acts as a gatekeeper/mediator of fljB/fliC expression. And export! Previously it was thought that if fljB is expressed then fljA must be acting as a transcription repressor – but it’s not its working posttranscriptionally – how cool is that? Eppendork thinks its hot shit so to speak.
Figure 1: Salmonella rocking an improperly prepared egg sandwich somewhere near you this lunchtime....
Which of course made me think about intelligent design – cause you gotta admit the complexity of this switch could give the foaming at the mouths id nutters cause for joy. The complexity and yet at the same time simplicity of it is stunning (the science to prove it was very cool - kudos people). So one thing lead to another when you are moi and here is where I ended up - that’s right peoples the concept of irreducible complexity – id proponents favourite chew toy. So I will dissemble for the non up-to-date with a quick evolution primer: the idea floating around is that there are certain biological systems are too complex to have evolved as they are – that there had to be an intelligent designer ie a God figure that created them just so and that if you took one piece of the design away it would all fall to pieces and all would be lost (IC has validity - just not the denial of evolution which is just sniffing some bad mojo). I may sound a bit sarky over here at the real scientists table but I have had this q and a with many different people - I am still firmly Darwin's bitch. But any who, nuff said on the snarchasm between Eppendork and the ID God squad.
The problem with the ID God squad is that they are slick - they have some pretty "solid" evidence - eyeballs, the bacterial flagella, antibodies, gene cascades - the "list" goes on - and they present pretty vids with tbh sexy cgi, and if you didnt know better you would think - that's reasonable. Well sorry sonny-Jim it isnt reasonable - it's insidious - i mean seriously have you looked at bacteria lately? Huh? Have you? They are like the poster child for Natural Selection and evolution - now showing in your local armpit! and you guys are holding them up as perfect examples of the Creator's intelligent design?? FFS - scuse Eppendork's language - she may be ranting now. So I am putting the verbal crow bar down now and walking away - I found this on youtube (may I say god bless spewtube for all its unsolicited and uncensored offerings) I like it - it's reasonable and based on the dirty word round the ID halls of residence (S.C.I.E.N.C.E).
Figure 2: Good point!
PS: Eppendork is not an Atheist - she fully believes in God - just not licentious ID dribble - that is all.
PPS: My favourite bits about the you tube videos are the unsolicited comments - god bless them all :)