BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//RLASKEY//CALENDEROUS//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260913T094512Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20110408T140000Z
DTEND:20110408T150000Z
UID:event790@bu.edu
URL:http://physics.bu.edu/internal/events/show/790
SUMMARY:Mikkel Jensen - Preliminary Oral Exam
DESCRIPTION:\nPart of the Preliminary Oral Exam.\n\nTitle:  Regulation of A
	ctin Mechanics\, Dynamics\, and Structure by Associated Actin-Binding Prote
	ins\nExamining Committee:  Ken Rothschild\, Jeffrey Moore\, Rama Bansil\, S
	id Redner\, Robert Carey\n\nAbstract:\nWe study the effect of two smooth mu
	scle actin-binding proteins\, calponin and caldesmon\, on the mechanics\, d
	ynamics\, and structure of filamentous actin.  The bending rigidity of acti
	n is determined by fluorescence microscopy of labeled actin filaments by tr
	eating the polymer as a worm-like chain.  Through a correlation function an
	alysis calponin is observed to reduce the actin persistence length\, a resu
	lt interpreted as a reduction of the Young’s modulus of the actin filamen
	t.  Calponin is also observed to destabilize the actin filament\, making it
	 more susceptible to severing by external shear forces.  These results are 
	discussed in light of work published on the actin severing protein cofilin 
	and are compared to the proposed model for actin severing by cofilin.\nFurt
	hermore\, we observe the caldesmon subfragment H32K by electron microscopy 
	to prolong a nascent state of the newly polymerized actin filament.  Actin 
	assembly is visualized by TIRF microscopy\, and H32K is shown to not affect
	 the rate of actin polymerization despite changes seen in bulk pyrene-fluor
	escence assays.  Implications and future experiments addressing the functio
	nal importance of this structural state are outlined.\nActin has been propo
	sed to have many structural states existing in equilibrium.  We discuss the
	 effects of both calponin and caldesmon in light of this hypothesis and dis
	cuss a connection between the internal structural states of actin and the m
	echanics and dynamics of the filament.\n\nBest wishes to Mikkel!!
LOCATION:PRB 365\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR