This time find­ing the most rel­e­vant posters of the ses­sion was a sim­ple task; they were all pretty much lined up in the poster session’s sub­group of “DNA, RNA Struc­ture & Con­for­ma­tion II”. And I must say, there was not a sin­gle one that did not imme­di­ately caught my inter­est!
Jun Lin from UCSB has taken on the dif­fi­cult task to shade light (in fact it’s done by YOYO-staining of tor­sion­ally con­straint DNA) on the for­ma­tion of plec­tonems in mag­netic tweez­ers exper­i­ments. He was explain­ing his exper­i­ments to his for­mer col­league Kipom Kim when I dropped by.

Espe­cially inter­est­ing where Her­gen Brutzer’s and Robert Schöpflin’s posters: Both next to each other deal­ing with the widely debated buck­ling tran­si­tion of double-stranded DNA. Her­gen did very care­ful and high res­o­lu­tion magnetic-tweezers mea­sure­ments (doi: 10.1016/j.bpj.2009.12.4292) and Robert com­ple­mented those with Monte-Carlo sim­u­la­tions. Bril­liantly aligned the­o­ret­i­cal and exper­i­men­tal studies!

Wow, what a poster ses­sion! Appar­ently, there was quite some inter­est in our work on the Allan vari­ance which mostly cov­ered our Optics Express and SPIE Pro­ceed­ing, because even after the “reg­u­lar stand-by time” peo­ple would not let me leave;-). Thanks to all of you that dropped by, I’ve learnt a lot and hope I could answer most of your ques­tions sufficiently.

The down­side was that I could not even remotely check as many inter­est­ing posters as antic­i­pated. And there were quite a few.
Fer­nando Moreno pre­sented some very, very nice AFM study on pre­ven­tion of DNA rean­neal­ing by a cer­tain heli­case.
Jan Lipfert showed new data on the TopIB project (mag­netic tweez­ers stud­ies with drug-resistant top­i­so­merase derivates) that I found espe­cially inter­est­ing as his results basi­cally con­firm pre­vi­ous find­ings which we did in Nynke Dekker’s lab.
I also did like Ram­sey Kamar’s poster. Therein he described one part of his grad work on the oligomer­iza­tion of the mem­brane pro­tein prestin. Pretty cool stuff.

There were quite a few more really, really good posters. I think this first poster ses­sion con­firms the trend of very strong con­tri­bu­tions to this meet­ing from the entire field of biophysics.

Quite a few peo­ple made it to the work­shops in the evening. They were rewarded with good pre­sen­ta­tions in par­tic­u­lar I want to give two thumbs up to Adam Cohen’s work that high­lighted his group’s effort in devel­op­ing neat biotech tools. [For the future: maybe grab’n’go sand­wiches just before the evening ses­sions would help to keep the audi­ence tight and together;-)]

Was there actu­ally any­body will­ingly miss­ing out on Steve Block’s talk? At least, none of the single-molecule peo­ple researchers, as the audi­to­rium was filled! Steve’s 30min-firework on the exper­i­ments car­ried out by Nicholas Guy­dosh at Stan­ford had as a goal noth­ing less, but tar­get­ing the long last­ing (and highly ranked) debate about how kinesin (another sub­fam­ily than the Kip3 Volker is look­ing at) walks on micro­tubuli. The idea is straight for­ward: instead of bind­ing an han­dle bead in an opti­cal tweez­ers assay to the tail, Steve and his cowork­ers sim­ply bind the bead directly to one of the walk­ing heads. They have achieved this by the use of a 23nm-DNA linker.

As the result: Kinesin walks with one head bound, ‘it’s so sim­ple.’ The extra­or­di­nary setup also allowed a time shared trap­ping assay, that even showed a directed, slight over­shoot­ing that might be related to the ADP release (around an one-nanometer struc­tural change in direc­tion of load). The story was great and com­plete, the Nature paper came in 2009.

The excel­lent talk by Cather­ine Royer on the inves­ti­ga­tion of gene reg­u­la­tory net­works by means of floures­cence tech­niques was inter­rupted by a power fail­ure in the lec­ture hall. Reg­u­lar con­fu­sion turned into some new cof­fee, though after six min­utes Cather­ine was back on.
Very well han­dling this sit­u­a­tion, she explained the het­erodimer for­ma­tion between cer-ER(alpha) and mcherry-ER(beta). This nucleus data was com­ple­mented by those about the CggR and CcpnR repres­sor net­work by fluc­tu­a­tions of floures­cently labelled pro­teins in E. coli. But are there any mod­els that take any­thing beyond sim­ple dif­fu­sion (even inside the cells) into account?
This is accord­ing to Cather­ine a very com­plex, very dif­fi­cult task. I def­i­nitely got really inter­ested in the pre­sented work, look­ing up this group’s papers etc. will hap­pen back in Copenhagen.

Eric Greene entered the stage just before the break, remind­ing us about their cool DNA cur­tains they do at Colum­bia. He looked at two pairs of dimer-forming primers (Mlh1-Pms1, Msh2-Msh6). The big­ger pic­ture he has in mind though is the bypass­ing of those pro­tein com­plexes on nucleosome-packed DNA. Funny thing: on his acknowl­edge­ment slide, we read

YOUR NAME HERE: ______

Was that meant as a job offer? And to whom? ;-)

After the cof­fee break, we were reminded of the Weber prize, find more details at lfd.uci.edu/weber/prize/.

I did like both of the stu­dents talks (I might drop my notes here later, when time per­mits). Richard Lude­scher took us on the entire his­tory les­son to finally arrive at the dif­fer­ence between floures­cence and phos­pho­res­cence. Or would you know by heart which one goes through the triplett state ;-)?

At the end of the first day, 1.5 really good ses­sions, expo­sure to good new ideas”, own poster put up, and a few peo­ple gath­ered for a good din­ner thing, don’t ask for much more.

Just one thing about arriv­ing to the Bio­phys­i­cal Soci­ety Meet­ing 2010: Have this bar­code thing printed, that was emailed to you before, and you will be done with reg­is­tra­tion quicker as read­ing this paragraph ;-)

Made it to the first sci­en­tific ses­sion and with a cup of cof­fee on may lap, three mem­bers of the Sub­group Mol­e­c­u­lar Bio­physics did the kick-off. From an exper­i­men­tal­ist point of view, James McK­night’s talk was the most inter­est­ing one. He and his group are inves­ti­gat­ing the villin-type head­piece super­fam­ily. Those pro­teins are involved in the defor­ma­tion of red blood cells. In his talk James focused on the sub­species dematin that con­sists of a 315-residues core domain and a 68-residues long head­piece that is able to bind to actin fil­a­ments. Since the core domain can form trimers with oth­ers, dematin enables actin bundling. He con­vinced us with some elec­tron micro­graphs of bundle/non-bundle form­ing dematin derivates. The phos­pho­ry­lated dematin also formed bun­dles, though in a dis­tinct fashion.

On the cel­lu­lar level, dematin is most often asso­ci­ated with the junc­tional com­plex that sta­bi­lizes star-like spec­trin pat­terns. It also links it to the mem­brane, thus might inhibit or at least alter the defor­ma­tion red blood cells. What would now be the role of some post-translational reg­u­la­tion such as phos­pho­ry­la­tion? In a nice and con­vinc­ing com­bi­na­tion of com­ple­men­tary tech­niques, such as CD spec­tra, gel elec­trophore­sis after ultra­cen­trifu­ga­tion, and NMR struc­tures a model was announced that focuses on the phos­pho­ry­lated residue, just three residues away from the end of the head domain. It is located on a very flex­i­ble linker, which data sug­gests can fold back on itself. In this state it would still be able to bind F-actin, although in a spa­tially dif­fer­ent fash­ion lead­ing to more con­fined actin struc­tures. To encounter for the vari­ety of states actu­ally found, James and his cowork­ers need the help of a steer­ing argument.

Ques­tions addressed again the role of dematin on the cel­lu­lar level, the pos­si­ble two F-actin bundling only (except three as work­ing hypoth­e­sis through the entire talk) and the flex­i­bil­ity mea­sures of the linker. Very nice and com­plete talk as a good start into the meet­ing. See what David Green has got to say about HIV after the cof­fee break.