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BEGIN:VEVENT
SUMMARY:Bill Bement (U Wisconsin Madison)
DTSTART;VALUE=DATE-TIME:20211018T150000Z
DTEND;VALUE=DATE-TIME:20211018T154000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/1
DESCRIPTION:Title: A versatile cytokinetic circuit based on Rho\, F-actin\, Ect2 and RGA
34\nby Bill Bement (U Wisconsin Madison) as part of BIRS workshop Math
ematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\n\n
Abstract\nCytokinesis in animal cells is dependent on the concentration of
active Rho (Rho-GTP or Rho-T) at the equatorial cell cortex\, where it di
rects formation of the F-actin (filamentous actin) and myosin-2-rich cytok
inetic apparatus. Immediately prior to and during cytokinesis\, the corte
x behaves as an excitable medium\, generating propagating waves of Rho act
ivity and F-actin assembly which become concentrated and amplified at the
equatorial cortex by the action of the mitotic spindle. Excitable dynamic
s implies the existence of a circuit based on positive feedback coupled to
delayed negative feedback. Previous work indicated that positive feedbac
k during cytokinesis is based on Rho-T and Ect2 (a Rho activator)\, while
negative feedback is somehow dependent on F-actin. Here we show that the
delayed feedback is based on the GAP (Rho inactivator) RGA34: RGA34 local
izes to waves that are concentrated and amplified at the equatorial cortex
\; RGA34 waves "chase" (follow) Rho-T waves\; RGA34 colocalizes with F-act
in\; experimental disruption or modulation of cortical F-actin results in
corresponding disruption or modulation of RGA34 distribution\; and\, most
compellingly\, coexpression of RGA34 and Ect2 in cells that are not normal
ly excitable is sufficient to induce high amplitude waves of Rho-T and F-a
ctin that pervade the entire cortex. Variation of the ratio of RGA34 to E
ct2 produces quantitative and qualitative changes in cortical dynamics\, w
ith low ratios producing pulsed contractions and high ratios producing ove
rtly psychedelic waves. We conclude that Rho\, F-actin\, Ect2 and RGA34 f
orm the core of a versatile cortical excitability circuit that regulates d
iverse cortical behaviors.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Buttenschoen (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20211018T154000Z
DTEND;VALUE=DATE-TIME:20211018T162000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/2
DESCRIPTION:Title: Spatio-temporal heterogeneities in a mechano-chemical model of collec
tive cell migration\nby Andreas Buttenschoen (University of British Co
lumbia) as part of BIRS workshop Mathematics of the Cell: Integrating Sign
aling\, Transport and Mechanics\n\n\nAbstract\nAbstract: Small GTPases\, s
uch as Rac and Rho\, are well known central regulators of cell morphology
and motility\, whose dynamics also play a role in coordinating collective
cell migration. Experiments have shown GTPase dynamics to be affected by b
oth chemical and mechanical cues\, but also to be spatially and temporally
heterogeneous. This heterogeneity is found both within a single cell\, an
d between cells in a tissue. For example\, sometimes the leader and follow
er cells display an inverted GTPase configuration. While progress on under
standing GTPase dynamics in single cells has been made\, a major remaining
challenge is to understand the role of GTPase heterogeneity in collective
cell migration. Motivated by recent one-dimensional experiments (e.g. mic
ro-channels) we introduce a one-dimensional modelling framework allowing u
s to integrate cell bio-mechanics\, changes in cell size\, and detailed in
tra-cellular signalling circuits (reaction-diffusion equations). Using thi
s framework\, we build cell migration models of both loose (mesenchymal) a
nd cohering (epithelial) tissues. We use numerical simulations\, and analy
sis tools\, such as bifurcation analysis\, to provide insights into the re
gulatory mechanisms coordinating collective cell migration. We show how lo
cal perturbations to GTPase signalling due to cell-cell interactions or te
nsion lead to a variety of dynamics\, resembling the behavior of small cel
l groups.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Garegin Papoian (University of Maryland)
DTSTART;VALUE=DATE-TIME:20211018T164000Z
DTEND;VALUE=DATE-TIME:20211018T172000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/3
DESCRIPTION:Title: Simulating Deformable Vesicles Containing Complex Cytoskeletal Networ
ks\nby Garegin Papoian (University of Maryland) as part of BIRS worksh
op Mathematics of the Cell: Integrating Signaling\, Transport and Mechanic
s\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ajay Gopinathan (University of California\, Merced)
DTSTART;VALUE=DATE-TIME:20211018T172000Z
DTEND;VALUE=DATE-TIME:20211018T180000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/4
DESCRIPTION:Title: From geometric incompatibility to function: Curvature sensing with tw
isted filaments\nby Ajay Gopinathan (University of California\, Merced
) as part of BIRS workshop Mathematics of the Cell: Integrating Signaling\
, Transport and Mechanics\n\n\nAbstract\nFilamentous biopolymers are invol
ved in a variety of critical cellular processes including facilitating int
racellular transport\, segregating genetic material and force production d
uring motility and cell division. In this talk\, I will discuss how geomet
rical incompatibility\, such as size or curvature mismatches\, between the
biopolymer structure and its environment can be translated into function.
As a particular example\, I will describe how the frustrated interplay be
tween the helicity of protein filaments\, their elasticity and their inter
actions with curved surfaces can lead to novel conformational states with
functional implications. Our work shows that biopolymers are inherently ve
ry sensitive to this coupling\, allowing twisted filaments to sense curvat
ure at length scales much larger than themselves. Such a coupling could be
exploited for the regulation of a variety of processes such as the target
ed exertion of forces\, signaling\, and self-assembly in response to geome
tric cues including the local mean and Gaussian curvatures. I will discuss
recent in vivo experiments to validate our predictions and conclude with
some of our latest work extending our formalism as well as future prospect
s.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ed Munro (University of Chicago)
DTSTART;VALUE=DATE-TIME:20211018T202000Z
DTEND;VALUE=DATE-TIME:20211018T210000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/5
DESCRIPTION:Title: Structural memory of filament alignment during contractile ring assem
bly in C. elegans embryos\nby Ed Munro (University of Chicago) as part
of BIRS workshop Mathematics of the Cell: Integrating Signaling\, Transpo
rt and Mechanics\n\n\nAbstract\nDuring cytokinesis in animal cells\, signa
ls from the mitotic apparatus position an equatorial zone of RhoA activit
y which drives local assembly of actin filaments and bipolar myosin II min
ifilaments. These in turn reorganize to form a circumferentially array of
filaments that constricts to drive cell division. But how cells rapidly b
uild and maintain this alignment in the face of continuous turnover of fil
aments and motors has remained somewhat mysterious. I will describe our re
cent efforts to resolve this mystery through a combination of high speed T
IRF microscopy\, single molecule imaging\, particle tracking analysis and
computational modeling. We have found that locally compressive flows\, dr
iven by myosin II\, reorient filaments to build alignment. However\, singl
e filaments turn over far too fast for reorientation of single filaments t
o do this job. Instead\, we find that long filaments assembled by formins
use existing filaments as templates to orient their growth. We refer to th
is process as filament guided filament assembly (FGFA). We show that FGFA
endows small filament bundles within the cortex with a structural memory
of filament orientation\; by tuning the strength of FGFA\, the duration of
this memory can be made arbitrarily long relative to the lifetimes of ind
ividual filaments. In particular\, we show that FGFA is sufficiently stron
g to explain the rapid emergence and stable persistence of orientation in
the C. elegans contractile ring. I will also discuss the implications of t
hese findings for the maintenance of cortical actin network architecture a
nd the microscopic origins of self-organized contractility.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Orion Weiner (University of California San Francisco))
DTSTART;VALUE=DATE-TIME:20211018T210000Z
DTEND;VALUE=DATE-TIME:20211018T214000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/6
DESCRIPTION:Title: Self-organization of actin regulators guides cell morphogenesis\n
by Orion Weiner (University of California San Francisco)) as part of BIRS
workshop Mathematics of the Cell: Integrating Signaling\, Transport and Me
chanics\n\n\nAbstract\nTo control their shape and movement\, cells leverag
e nucleation promoting factors (NPFs) to regulate when and where they poly
merize actin. Despite having similar upstream activators and downstream e
ffectors\, different NPFs organize dramatically different membrane deforma
tions ranging from finger-like filopodia to sheet-like lamellipodia to end
ocytic membrane invaginations. We seek to understand the local rules tha
t underlie these disparate morphological programs. We have uncovered dif
ferent patterns of protein oligomerization and geometry-sensing that regul
ate two important regulators of cell movement. The WAVE complex oligomeri
zes into a saddle-sensing linear template that could explain expanding sel
f-straightening lamellipodia. In contrast\, the homologous NPF WASP repurp
oses an arrested endocytic-like program to connect substrate topology to c
ell polarity. Our work suggests how feedback between cell shape and actin
regulators instructs cell morphogenesis.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adriana Dawes (he Ohio State University)
DTSTART;VALUE=DATE-TIME:20211018T220000Z
DTEND;VALUE=DATE-TIME:20211018T224000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/7
DESCRIPTION:Title: Dynein localization and pronuclear movement in the early C. elegans e
mbryo\nby Adriana Dawes (he Ohio State University) as part of BIRS wor
kshop Mathematics of the Cell: Integrating Signaling\, Transport and Mecha
nics\n\n\nAbstract\nAsymmetric cell division\, where daughter cells inheri
t unequal amounts of specific factors\, is critical for development and ce
ll fate specification. In polarized cells\, where specific factors are seg
regated to opposite ends of the cell\, asymmetric cell division occurs as
a result of dynein-mediated centrosome positioning along the polarity axis
. Early embryos of the nematode worm C. elegans polarize in response to fe
rtilization\, and rely on proper centrosome positioning for cell fate spec
ification and development. Depletion of certain proteins results in defect
ive movement of centrosomes and the associated pronuclear complex in the e
arly embryo. We developed a novel measure to characterize the oscillatory
nature of these movement defects\, and demonstrated that dynein localizati
on is not impaired in the presence of wobble. Stochastic and continuum mod
eling of the centrosome and pronuclear complex movement is being used to i
dentify possible mechanisms responsible for the impaired movement.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stéphanie Portet (University of Manitoba)
DTSTART;VALUE=DATE-TIME:20211018T224000Z
DTEND;VALUE=DATE-TIME:20211018T232000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/8
DESCRIPTION:Title: Transport of intermediate filaments in cells\nby Stéphanie Porte
t (University of Manitoba) as part of BIRS workshop Mathematics of the Cel
l: Integrating Signaling\, Transport and Mechanics\n\n\nAbstract\nTogether
with actin and microtubules\, intermediate filaments (IFs) are essential
components of the cytoskeleton. IF proteins self-assemble into long elasti
c filaments organized in networks. Intracellular transport of IFs is essen
tial for the dynamic rearrangements of the network and is regulated by int
racellular signals. Network dynamics and organization regulate IF cellular
functions.\nIn collaboration with experimentalists\, we have been working
on deciphering the features of the intracellular transport of IFs that re
sults from the interplay between actin-dependent retrograde flow\, and ant
erograde and retrograde microtubule-dependent transports driven by process
ive motors kinesin-1 and dynein. I will present an overview of models and
data we have been developing for a few years.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Fai (Brandeis University)
DTSTART;VALUE=DATE-TIME:20211019T154000Z
DTEND;VALUE=DATE-TIME:20211019T162000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/10
DESCRIPTION:Title: Coarse-grained stochastic model of myosin-driven vesicles into dendr
itic spines\nby Thomas Fai (Brandeis University) as part of BIRS works
hop Mathematics of the Cell: Integrating Signaling\, Transport and Mechani
cs\n\n\nAbstract\nWe model vesicle transport into dendritic spines\, which
are micron-sized structures located at the postsynapses of neurons charac
terized by their thin necks and bulbous heads. Recent high-resolution 3D i
mages show that spine morphologies are highly diverse. To study the influe
nce of geometry on transport\, our model reduces the fluid dynamics of ves
icle motion to two essential parameters representing the system geometry a
nd elasticity. Upon including competing molecular motor species that push
and pull on vesicles\, the model exhibits multiple steady states that neur
ons could exploit in order to control the strength of synapses. Moreover\,
the small numbers of motors lead to random switching between these steady
states. We describe a method that incorporates stochasticity into the mod
el to predict the probability and mean time of translocation as a function
of spine geometry.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Paul Bressloff (University of Utah)
DTSTART;VALUE=DATE-TIME:20211019T164000Z
DTEND;VALUE=DATE-TIME:20211019T172000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/11
DESCRIPTION:Title: Biological pattern formation: beyond classical diffusion-based morph
ogenesis\nby Paul Bressloff (University of Utah) as part of BIRS works
hop Mathematics of the Cell: Integrating Signaling\, Transport and Mechani
cs\n\n\nAbstract\nA fundamental question in modern cell biology is how cel
lular and subcellular structures are formed and maintained given their par
ticular molecular components. How are the different shapes\, sizes\, and f
unctions of cellular organelles determined\, and why are specific structur
es formed at particular locations and stages of the life cycle of a cell?
In order to address these questions\, it is necessary to consider the theo
ry of self-organizing non-equilibrium systems. We are particularly interes
ted in identifying and analyzing novel mechanisms for pattern formation th
at go beyond the standard Turing mechanism and diffusion-based mechanisms
of protein gradient formation. In this talk we present three examples of n
on-classical biological pattern formation: (i) Transport models of cytonem
e-based morphogenesis. (ii) Space-dependent switching diffusivities and cy
toplasmic protein gradients in the C. elegans zygote (iii) Hybrid Turing m
echanism for the homeostatic control of synaptogenesis in C. elegans.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandria Volkening (Purdue University)
DTSTART;VALUE=DATE-TIME:20211019T172000Z
DTEND;VALUE=DATE-TIME:20211019T180000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/12
DESCRIPTION:Title: Modeling and topological data analysis of zebrafish patterns\nby
Alexandria Volkening (Purdue University) as part of BIRS workshop Mathema
tics of the Cell: Integrating Signaling\, Transport and Mechanics\n\n\nAbs
tract\nWild-type zebrafish are small fish named for their dark and light s
tripes\, but mutant zebrafish feature variable skin patterns\, including s
pots and labyrinth curves. All of these patterns form as the fish grow due
to the interactions of tens of thousands of pigment cells in the skin. Th
is leads to the question: how do cell interactions change to create mutant
patterns? The longterm motivation for my work is to help shed light on th
is question and better link genes\, cell behavior\, and visible animal cha
racteristics. Toward this goal\, I develop agent-based and continuum model
s to describe cell behavior in growing 2D domains. However\, my agent-base
d models are stochastic and have many parameters\, and comparing simulated
patterns and fish images is often a qualitative process. In this talk\, I
will overview our models and discuss how methods from topological data an
alysis can be used to quantitatively describe cell-based patterns and comp
are in vivo and in silico images.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Padmini Rangamani (UCSD)
DTSTART;VALUE=DATE-TIME:20211019T193000Z
DTEND;VALUE=DATE-TIME:20211019T201000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/13
DESCRIPTION:Title: Elucidating the role of membrane tension in cellular processes using
continuum modeling\nby Padmini Rangamani (UCSD) as part of BIRS works
hop Mathematics of the Cell: Integrating Signaling\, Transport and Mechani
cs\n\n\nAbstract\nMembrane tension plays a critical role in many cellular
processes. Experiments using both cellular and reconstituted systems have
shown that tension plays a critical role in membrane-protein interactions
for curvature generation. Cellular membranes can be thought of as elastic
lipid bilayers that contain a variety of proteins\, including ion channels
\, receptors and scaffolding proteins. These proteins are known to diffuse
and aggregate in the plane of the membrane and to influence the bending o
f the membrane. Experiments have shown that lipid flow in the plane of the
membrane is closely coupled with the diffusion and aggregation of protein
s. Thus\, there is a need for a comprehensive framework that accounts for
the interplay between these processes. In this talk\, I will discuss some
recent theoretical and computational developments from my group using cont
inuum modeling that allows for better comparison of membrane deformations
with experiments. Our primary focus will be membrane trafficking\, particu
larly endocytosis but the theoretical developments are broadly applicable
to many membrane curvature generating processes.\n\n\nWe formulate the fre
e energy of the membrane with a Helfrich-like curvature elastic energy den
sity function modified to account for the chemical potential energy of the
proteins. We derive the conservation laws and equations of motion for thi
s system. Finally\, we present results from dimensional analysis and numer
ical simulations and demonstrate the effect of coupled transport processes
in governing the dynamics of membrane bending\, protein aggregation\, and
diffusion. We find that feedback between curvature and aggregation result
s in domains that result in membrane microdomains. This work is in collabo
ration with David Saintillan (UCSD\, MAE).\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wouter-Jan Rappel (University of California\, San Diego)
DTSTART;VALUE=DATE-TIME:20211019T201000Z
DTEND;VALUE=DATE-TIME:20211019T205000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/14
DESCRIPTION:Title: Combining experiments and modeling to better understand chemotaxis
a>\nby Wouter-Jan Rappel (University of California\, San Diego) as part of
BIRS workshop Mathematics of the Cell: Integrating Signaling\, Transport
and Mechanics\n\n\nAbstract\nMany motile eukaryotic cells can respond to e
xternal chemical gradients\, \nresulting in direct motion. During this mot
ion\, cells can use and switch between \ndifferent modes of migration. To
better understand these different modes\, \nwe combine experiments\, that
use traction force and fluorescent microscopy\, \nand modeling.
Specifically\, we quantitatively determine the distribution of \nof actin
and myosin and correlate these with traction force patterns in eukaryotic
cells \nthat move and switch between keratocyte-like fan-shaped\, oscillat
ory\, \nand amoeboid modes. We find that the wave dynamics of the cytoskel
etal components \ncritically determine the traction force pattern\, cell m
orphology\, and migration mode. \nFurthermore\, we find that fan-shaped ce
lls can exhibit two different propulsion \nmechanisms\, each with a distin
ct traction force pattern. Finally\, we show that \nthe traction force pat
terns can be recapitulated using the computational model\, \nwhich uses th
e experimentally determined spatio-temporal distributions of actin \nand m
yosin forces and a viscous cytoskeletal network. Our results suggest that
\ncell motion can be generated by friction between flow of this network an
d the substrate.\n\nAuthors:\nElisabeth Ghabache\, Yuansheng Cao\, Yuchuan
Miao*\, Alex Groisman\, Peter N. Devreotes*\, Wouter-Jan Rappel\n\nDepart
ment of Physics\, University of California\, San Diego\, La Jolla\, Califo
rnia 92093\, USA\n*Department of Cell Biology\, Johns Hopkins University\,
Baltimore\, MD\, USA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruth Baker (University of Oxford)
DTSTART;VALUE=DATE-TIME:20211019T205000Z
DTEND;VALUE=DATE-TIME:20211019T213000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/15
DESCRIPTION:Title: Quantifying the impact of electric fields on single-cell motility\nby Ruth Baker (University of Oxford) as part of BIRS workshop Mathemati
cs of the Cell: Integrating Signaling\, Transport and Mechanics\n\nAbstrac
t: TBA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Odde (University of Minnesot)
DTSTART;VALUE=DATE-TIME:20211019T220000Z
DTEND;VALUE=DATE-TIME:20211019T224000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/16
DESCRIPTION:Title: Cellular sensing of material stiffness and negative durotaxis\nb
y David Odde (University of Minnesot) as part of BIRS workshop Mathematics
of the Cell: Integrating Signaling\, Transport and Mechanics\n\n\nAbstrac
t\nThe ability of cells to sense the mechanical stiffness of their environ
ment is critical to their function\, and allows cells to migrate in a stif
fness-dependent manner. In my talk I will describe how we have developed a
computational motor-clutch model for the biophysics of cell migration and
applied it to glioma cell migration. Whereas an extensive literature acro
ss a wide range of cell types demonstrates the phenomenon of durotaxis –
the tendency of cells to migrate toward mechanically stiffer environments
– we demonstrate that our motor-clutch cell migration model (Bangasser
et al.\, Nat Comm\, 2017) predicts “negative durotaxis” – biased mig
ration toward softer environments – which we confirm experimentally for
the first time. Also\, we used the model to mechanically phenotype genetic
ally induced glioma mouse models. The biophysical modeling and experiments
help point us toward potentially new therapeutic strategies.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Coombs (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20211019T224000Z
DTEND;VALUE=DATE-TIME:20211019T232000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/17
DESCRIPTION:Title: A hierarchy of hidden Markov methods for single particle tracking\nby Daniel Coombs (University of British Columbia) as part of BIRS works
hop Mathematics of the Cell: Integrating Signaling\, Transport and Mechani
cs\n\n\nAbstract\nHidden Markov models (HMM) provide a powerful tool for a
nalysis of particle mobility. Briefly\, labelled objects are assumed to ex
ist in discrete states\, where each state has a distinct mode of mobility
- commonly\, Brownian diffusion with a state-dependent diffusivity. In thi
s talk\, I will describe a set of HMM\, beginning with simplest\, two-stat
e model\, developing to many states\, and discussing how we can allow for
experimental positional uncertainties. I’ll show results using simulated
data\, as well as using experimental data for motion of membrane receptor
s on the surfaces of lymphocytes. The methods shown in this talk were deve
loped jointly with Raibatak Das\, Jennifer Morrison\, Suzanne ten Hage and
especially Rebeca Cardim Falcao.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:William Holmes (Vanderbilt)
DTSTART;VALUE=DATE-TIME:20211019T150000Z
DTEND;VALUE=DATE-TIME:20211019T154000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/18
DESCRIPTION:Title: Modeling intra-cellular insulin transport dynamics in pancreatic Bet
a cells ↓\nby William Holmes (Vanderbilt) as part of BIRS workshop M
athematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\
n\nAbstract\nIn this talk\, I will discuss the role of cytoskeletal-mediat
ed transport (by microtubules) in regulating insulin dynamics in pancreati
c cells. Due to the increasing prevalence of diabetes and related disorder
s\, understanding how individual cells regulate insulin availability and s
ecretion in response to glucose stimulation is of utmost importance. While
it has been known for decades that dysregulated microtubule dynamics alte
r insulin secretion\, their role in insulin regulation has been murky. Her
e I use computational modeling to demonstrate a new mechanism by which app
arently random trafficking of insulin on a random network of microtubules
regulates the intra-cellular localization and availability of insulin. The
se results demonstrate that microtubule mediated trafficking negatively re
gulates insulin secretion. Accompanying experiments confirm this hypothesi
s and demonstrate the potential for targeting of microtubule dynamics to p
rovide a new avenue to manipulate insulin secretion.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Melissa Rolls (Penn State University)
DTSTART;VALUE=DATE-TIME:20211020T150000Z
DTEND;VALUE=DATE-TIME:20211020T154000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/19
DESCRIPTION:Title: Mechanisms and modeling of neuronal microtubule dynamics and polarit
y\nby Melissa Rolls (Penn State University) as part of BIRS workshop M
athematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\
n\nAbstract\nThe polarity and stability of the microtubule cytoskeleton ar
e critical in supporting long-range directed transport of cellular cargo a
nd long-term survival of neurons. However\, microtubules also need to be d
ynamic and reorganize in response to injury events. Using live imaging and
genetics\, multiple mechanisms that contribute to the primarily minus-end
-out filament organization in Drosophila dendrites have been identified. T
hese include local microtubule nucleation\, quality control of new microtu
bules and microtubule steering. Our objective is to understand how these c
omplex mechanisms ensure both healthy function over long time periods and
dramatic rearrangement in response to injury. To this end\, we propose a s
patially-explicit mathematical model of the dendritic microtubule system i
n Drosophila neurons. The stochastic modeling framework includes microtubu
le turnover dynamics and a spatial multiscale model that captures microtub
ule organization in branched dendrites. The model predicts the maintenance
of polarity in simulated microtubule populations. Paired with biological
experiments\, this modeling framework has the potential to provide insight
into the impact of turnover parameters as well as of individual polarity
control mechanisms\, such as steering and nucleation\, on polarity and dyn
amics in Drosophila dendrites. Joint talk with Veronica Ciocanel.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Peter Kramer (Rensselaer Polytechnic Institute)
DTSTART;VALUE=DATE-TIME:20211020T154000Z
DTEND;VALUE=DATE-TIME:20211020T162000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/20
DESCRIPTION:Title: Spatial Parameterization of Attachment Processes in Molecular Motor-
Cargo Systems\nby Peter Kramer (Rensselaer Polytechnic Institute) as p
art of BIRS workshop Mathematics of the Cell: Integrating Signaling\, Tran
sport and Mechanics\n\n\nAbstract\nIntracellular transport is conducted la
rgely by molecular motor proteins which process along cytoskeletal filamen
ts\, from which they can attach or detach. We describe an analytical frame
work to characterize motor attachment or reattachment rates to microtubule
s as a function of the physical and geometric properties of the motor\, th
e cargo to which it is attached\, and possibly a second motor attached to
the same cargo and a microtubule. The biophysical model is coarse-grained
at the level of the macromolecular motors and formulated in terms of stoc
hastic differential equations\, allowing for rotation of the cargo and non
linear force laws for the motor-cargo tether. Various asymptotic approxim
ations based on ``small target'' first passage time calculations are possi
ble depending on the relationship of the motor-cargo tether length\, the d
istance between microtubules\, whether the cargo has a rigid or lipid memb
rane surface\, and the initial configuration of the motor and cargo relati
ve to the microtubules. The same methodology also allows the computation
of the probability distribution for which nearby microtubule a motor will
attach next. These results have potential application for modeling motor
attachment in engineered systems where\, for example\, the cargo is introd
uced in a geometrically controlled way by optical trap or flow.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christine Payne (Duke)
DTSTART;VALUE=DATE-TIME:20211020T164000Z
DTEND;VALUE=DATE-TIME:20211020T172000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/21
DESCRIPTION:Title: Intracellular transport of lysosomes decreases in the perinuclear re
gion: Insights from changepoint analysis\nby Christine Payne (Duke) as
part of BIRS workshop Mathematics of the Cell: Integrating Signaling\, Tr
ansport and Mechanics\n\n\nAbstract\nLysosomes are membrane-bound organell
es responsible for processing endocytic molecules\, particles\, and viruse
s\, phagocytic destruction of pathogens\, and the cellular housekeeping of
autophagy. These cellular functions require intracellular transport. A co
llaborative team led by Prof. Christine Payne in the Department of Mechani
cal Engineering and Materials Science at Duke University and Prof. Scott M
cKinley in the Department of Mathematics at Tulane University\, enabled by
the NSF-Simons Foundation Southeast Center for Mathematics and Biology (S
CMB)\, has investigated the intracellular transport of these organelles. W
e use fluorescence microscopy to characterize the motion of lysosomes as a
function of intracellular region\, perinuclear or periphery\, and lysosom
e diameter. Single particle tracking data is complemented by changepoint i
dentification and analysis of a mathematical model for state-switching. We
classify motion as motile or stationary and then study how lysosome locat
ion and diameter affects the proportion of time spent in each state and th
e speed during motile periods. We find that the proportion of time spent s
tationary is strongly region-dependent with significantly decreased motili
ty in the perinuclear region. Increased diameter only slightly decreases s
peed. These results show that intracellular region\, rather than lysosome
diameter\, is a major factor in the motion of lysosomes. Overall\, these r
esults demonstrate the importance of decomposing particle trajectories int
o qualitatively different behaviors before conducting population-wide stat
istical analysis. This approach shows that intracellular region\, which is
not regularly included as a factor in studies of intracellular transport\
, is a major factor.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scott McKinley (Tulane University)
DTSTART;VALUE=DATE-TIME:20211020T172000Z
DTEND;VALUE=DATE-TIME:20211020T180000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/22
DESCRIPTION:Title: On the use and misuse of Bayesian methods for uncertainty quantifica
tion\nby Scott McKinley (Tulane University) as part of BIRS workshop M
athematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\
n\nAbstract\nAn intrinsic challenge in studying intracellular transport is
that the time scale of experimental observation is far shorter than the t
ime scales associated with many biological events of interest. This is why
mathematical modeling is so important -- making good predictions is impos
sible without good models -- but it can be difficult to associate predicti
ons with credible quantifications of uncertainty. In this talk\, in which
I will review a Bayesian approach to communicating predictions with uncer
tainty\, visiting some successes and failures I’ve experienced along the
way. One issue that arises is that a “fully principled” UQ approach c
an be computationally prohibitive\, and can even introduce biophysically u
nrealistic results. Some compromises must be made\, but where and how are
open for debate. My hope is to open a conversation within the workshop abo
ut how others view the communication of uncertainty\, and whether and how
we should teach these methods in our graduate programs.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Mogilner (New York University)
DTSTART;VALUE=DATE-TIME:20211021T150000Z
DTEND;VALUE=DATE-TIME:20211021T154000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/23
DESCRIPTION:Title: Rapid and accurate assembly of mitotic spindle\nby Alex Mogilner
(New York University) as part of BIRS workshop Mathematics of the Cell: I
ntegrating Signaling\, Transport and Mechanics\n\n\nAbstract\nMitotic spin
dle is a remarkable molecular machine segregating chromosomes and position
ing\ncytokinetic ring prior to cell division. The spindle self-assembles f
rom centrosomes\,\nmicrotubules and chromosomes very rapidly and accuratel
y. For decades\, the so-called\nsearch-and-capture model of this self-asse
mbly was dominant. This model posited that\nthe microtubules randomly prob
e the cell space until\, by chance\, all chromosomes are\nconnected to the
spindle. Recent data puts this model in doubt. I will show that both\ncur
rent data and stochastic computational model argue that a much more determ
inistic \nprocess of polarity sorting in a complex microtubule-motor syste
m accounts for the rapid \nand accurate assembly of the spindle. Notably\,
both centripetal chromosome transport\, and\nchromosome connection mechan
ics are the key to speed and accuracy.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Samuel Isaacson (Boston University)
DTSTART;VALUE=DATE-TIME:20211021T154000Z
DTEND;VALUE=DATE-TIME:20211021T162000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/24
DESCRIPTION:Title: Stochastic Reaction-Drift-Diffusion Methods for Studying Cell Signal
ing\nby Samuel Isaacson (Boston University) as part of BIRS workshop M
athematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\
n\nAbstract\nParticle-based stochastic reaction-diffusion (PBSRD) models a
re one approach to study biological systems in which both the noisy diffus
ion of individual molecules\, and stochastic reactions between pairs of mo
lecules\, may influence system behavior. They provide a more microscopic m
odel than deterministic reaction-diffusion PDEs or stochastic reaction-dif
fusion SPDEs\, which treat molecular populations as continuous fields. The
reaction-diffusion master equation (RDME) and convergent RDME (CRDME) are
lattice PBSRD models\, with the latter providing a convergent approximati
on to the spatially-continuous volume-reactivity PBSRD model as the lattic
e spacing is taken to zero. In this talk I will present several generaliza
tions of the RDME and CRDME to support spatial transport mechanisms needed
for resolving spatially-distributed cellular signaling processes in gener
al geometries\, including drift due to background potentials\, interaction
potentials between molecules\, and continuous-time random walks to approx
imate molecular transport on surfaces.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fred Chang (UCSF)
DTSTART;VALUE=DATE-TIME:20211021T164000Z
DTEND;VALUE=DATE-TIME:20211021T172000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/25
DESCRIPTION:Title: Role of osmotic forces in determining the size of the nucleus\nb
y Fred Chang (UCSF) as part of BIRS workshop Mathematics of the Cell: Inte
grating Signaling\, Transport and Mechanics\n\n\nAbstract\nThe size of the
nucleus scales with cell size so that the nuclear-to-cell volume ratio (N
C Ratio) is maintained during cell growth. The mechanism responsible for t
his scaling is still mysterious. Nuclear volume is not determined merely b
y DNA amount\, but is influenced by factors such and nuclear transport and
nuclear envelope mechanics. Here\, we develop a quantitative model for nu
clear size control and scaling based upon colloid osmotic pressure that is
determined by numbers of macromolecules in the nucleoplasm and cytoplasm.
Osmotic shift experiments show that in the fission yeast\, the nucleus b
ehaves as an ideal osmometer. Perturbations that disrupt the relative num
bers of macromolecules in each compartment lead to predictable changes in
the NC ratio. Further this model provides an explanation for NC ratio home
ostasis behavior. These studies highlight the primary role of osmotic forc
es that determine the size of the nucleus and possibly other organelles.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maitreyi Das (University of Tennessee Knoxville)
DTSTART;VALUE=DATE-TIME:20211021T172000Z
DTEND;VALUE=DATE-TIME:20211021T180000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/26
DESCRIPTION:Title: Spatiotemporal regulation of Cdc42 activity organizes cytokinetic ev
ents\nby Maitreyi Das (University of Tennessee Knoxville) as part of B
IRS workshop Mathematics of the Cell: Integrating Signaling\, Transport an
d Mechanics\n\n\nAbstract\nCell polarization is a fundamental process by w
hich proteins asymmetrically localize to their functional site in response
to a signal thus determining cell shape. One of the major regulators of p
olarization is the highly conserved small GTPase Cdc42. Cdc42 is activated
at the sites of cell growth in a dynamic manner. In fission yeast\, activ
e Cdc42 displays an anti-correlated oscillatory pattern that determines ce
ll polarity and dimension. This oscillatory behavior of Cdc42 activation i
s an outcome of self-organizing positive and time-delayed negative feedbac
k loops. Cdc42 is also activated at the division site during cytokinesis\,
but here it does not display a similar oscillatory pattern. Using the fis
sion yeast model system\, we have shown that Cdc42 at the division site pr
omotes polarization during cytokinesis. We find that once the actomyosin r
ing is assembled\, membrane trafficking at specific sites and times enable
s different steps in cytokinesis. Membrane trafficking events allow delive
ry of membrane and enzymes necessary for furrow formation and septum/cell
wall synthesis\, respectively. Later\, trafficking is also required for th
e delivery of glucanases that promote cell separation. It is not clear how
the cell spatiotemporally organizes these precise membrane trafficking ev
ents during cytokinesis. We find that the Cdc42 activation pattern at the
division site matches that of these trafficking events. This Cdc42 activi
ty pattern spatiotemporally regulates membrane trafficking during cytokine
sis. Our data indicate that this pattern arises as a result of the interpl
ay between the positive and negative regulators of Cdc42 which in turn ena
bles spatiotemporal organization of cytokinetic events. Understanding how
the same regulators give rise to distinct activation patterns at the cell
ends compared to the division site will help to understand how cells spati
otemporally organize complex multi-step events such as cytokinesis and pol
arized growth.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Timothy Elston (University of North Carolina\, Chapel Hill)
DTSTART;VALUE=DATE-TIME:20211021T193000Z
DTEND;VALUE=DATE-TIME:20211021T201000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/27
DESCRIPTION:Title: Modeling polarity establishment\nby Timothy Elston (University o
f North Carolina\, Chapel Hill) as part of BIRS workshop Mathematics of th
e Cell: Integrating Signaling\, Transport and Mechanics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitrios Vavylonis (Lehigh University)
DTSTART;VALUE=DATE-TIME:20211021T201000Z
DTEND;VALUE=DATE-TIME:20211021T205000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/28
DESCRIPTION:Title: Cytoskeletal and membrane flows for cell polarization and motility
a>\nby Dimitrios Vavylonis (Lehigh University) as part of BIRS workshop Ma
thematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\n
\nAbstract\nThe ability of cells to polarize\, move by crawling\, or divid
e\, requires coordinated interactions of the cytoskeleton with membranes a
s well as with signaling systems organizing on membranes. Predictive model
s of these mechanisms of subcellular organization requires accounting of h
ow interactions at the molecular level lead to collective behavior involvi
ng patterns\, flows and forces over cellular scales. I will describe two
recent examples of how mathematical and computational modeling by our grou
p was combined with experiments by collaborators to make progress on under
standing membrane and cytoskeletal flow and turnover at regions of cell ex
tension. In the first example\, we showed that polarized exocytosis causes
lateral membrane flows away from regions of membrane insertion. In rod-sh
aped fission yeast cells\, this causes membrane-bound inhibitors of Cdc42
with sufficiently low diffusion and/or detachment rates to deplete\, thus
patterning the growing cell tip in way that establishes its rod shape. In
the second example\, we looked at actin cytoskeleton retrograde flows in r
egions of cell protrusion. Using filament-level kinetic and mechanical mod
els we provided an explanation of how distributed turnover through severin
g and annealing generates structural changes of Arp2/3-complex dendritic n
etworks. We also provide a filament-level implementation of the clutch mec
hanism and force transmission through the whole lamellipodial actin networ
k flowing over focal adhesions.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Grace McLaughlin (University of North Carolina Chapel Hill)
DTSTART;VALUE=DATE-TIME:20211021T205000Z
DTEND;VALUE=DATE-TIME:20211021T213000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/29
DESCRIPTION:Title: Modeling Asynchronous Nuclear Division\nby Grace McLaughlin (Uni
versity of North Carolina Chapel Hill) as part of BIRS workshop Mathematic
s of the Cell: Integrating Signaling\, Transport and Mechanics\n\n\nAbstra
ct\nMultinucleate cells are common in biology\, with examples including mu
scle cells\, placenta\, and fungi. Despite this\, many aspects of their ce
ll biology are not well understood. Dividing nuclei residing in a common c
ytosol would be expected to synchronize\, as the oscillating levels of cel
l cycle regulators from each nucleus should in theory entrain neighbors. H
owever\, in the multinucleate fungus Ashbya Gossypii\, spatially neighbori
ng nuclei have been observed to divide out of sync. Here we mathematically
model Ashbya nuclei as a dynamically growing system of coupled phase osci
llators to determine possible mechanisms that could lead to asynchronous d
ivision. Nuclear movement in space is modeled to capture core features of
Ashbya nuclear dynamics\, including both repulsion of and rearrangement wi
th neighbors. We study the effects of mobility\, cytosolic compartmentaliz
ation\, inhibitory signals\, and noise on transient phase dynamics. To co
mpare the model with experimental results\, we develop a nuclear tracking
pipeline with the aim of tracking nuclei during bypassing events\, identif
ying nuclear division\, and linking nuclei into hyphae. Initial results su
ggest a combination of locally and globally acting mechanisms might be at
play leading to the observed dynamics in Ashbya.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jian Liu (Johns Hopkins University)
DTSTART;VALUE=DATE-TIME:20211021T220000Z
DTEND;VALUE=DATE-TIME:20211021T224000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/30
DESCRIPTION:Title: Spatial control over near-critical-point operation ensures fidelity
of ParABS-mediated DNA partition\nby Jian Liu (Johns Hopkins Universit
y) as part of BIRS workshop Mathematics of the Cell: Integrating Signaling
\, Transport and Mechanics\n\n\nAbstract\nIn bacteria\, most low-copy-numb
er plasmid and chromosomally encoded partition systems belong to the tripa
rtite ParABS partition machinery. Despite the importance in genetic inheri
tance\, the mechanisms of ParABS-mediated genome partition are not well un
derstood. Combining theory and experiment\, we provided evidence that the
ParABS system – DNA partitioning in vivo via the ParA gradient-based Bro
wnian ratcheting – operates near a transition point in parameter space (
i.e.\, a critical point)\, across which the system displays qualitatively
different motile behaviors. This near-critical-point operation adapts the
segregation distance of replicated plasmids to the half-length of the elon
gating nucleoid\, ensuring both cell halves to inherit one copy of the pla
smids. Further\, we demonstrated that the plasmid localizes the cytoplasmi
c ParA to buffer the partition fidelity against the large cell-to-cell flu
ctuations in ParA level. The spatial control over the near-critical-point
operation not only ensures both sensitive adaption and robust execution of
partitioning\, but also sheds light on the fundamental question in cell b
iology: How do cells faithfully measure cellular-scale distance by only us
ing molecular-scale interactions?\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Will Hancock (Penn State University)
DTSTART;VALUE=DATE-TIME:20211021T224000Z
DTEND;VALUE=DATE-TIME:20211021T232000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/31
DESCRIPTION:Title: The role of the fluid lipid bilayer in kinesin-driven vesicle transp
ort\nby Will Hancock (Penn State University) as part of BIRS workshop
Mathematics of the Cell: Integrating Signaling\, Transport and Mechanics\n
\n\nAbstract\nMost cargo carried by kinesin motors are membrane bound\, wh
ich has implications for motor-based transport. We are investigating the
role of membrane fluidity in kinesin-based transport using two geometries
– a supported lipid bilayer and free vesicles. From attaching motors to
a supported lipid bilayer\, we can estimate the effect of the membrane on
motor on- and off-rates. By taking these values\, we can interpret our v
esicle experiments where we find that run length increases with increasing
motor numbers. Notably\, clustering motors enhances the motor run length
\, showing that the geometry of motor attachment to lipid bilayers may be
a regulator of bidirectional transport.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Khanh Dao Duc (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20211022T150000Z
DTEND;VALUE=DATE-TIME:20211022T154000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/32
DESCRIPTION:Title: Impact of ribosomes on translation across scales and new metrics for
biological shape analysis\nby Khanh Dao Duc (University of British Co
lumbia) as part of BIRS workshop Mathematics of the Cell: Integrating Sign
aling\, Transport and Mechanics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jay Newby (University of Alberta)
DTSTART;VALUE=DATE-TIME:20211022T154000Z
DTEND;VALUE=DATE-TIME:20211022T162000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/33
DESCRIPTION:Title: Dynamic self organization and microscale fluid properties of nucleop
lasm\nby Jay Newby (University of Alberta) as part of BIRS workshop Ma
thematics of the Cell: Integrating Signaling\, Transport and Mechanics\n\n
\nAbstract\nThe principal function of the nucleus is to facilitate storage
\, retrieval\, and maintenance of the genetic information. A unique featur
e of nucleoplasm—the fluid of the nucleus—is that it contains chromati
n (DNA) and RNA. In contrast to other important biological polymer hydroge
ls\, such as mucus and extracellular matrix\, the nucleic acid polymers ha
ve a sequence that encodes both genetic information and strongly influence
s spatial organization. How does crowding in a sequence specific hydrogel
influence spatial organization of the dynamic molecular components respons
ible for nuclear function? We are becoming increasingly aware of the role
of liquid-liquid phase separation (LLPS) in cellular processes in the nucl
eus and the cytoplasm. Complex molecular interactions over a wide range of
timescales can cause large biopolymers (RNA\, protein\, etc) to phase sep
arate from the surrounding nucleoplasm or cytoplasm into distinct bioconde
nsates (spherical droplets in the simplest cases). I will discuss recent w
ork modelling the role of nuclear biocondensates in neurodegenerative dise
ase and several ongoing projects related to modelling and microscopy image
analysis.\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Chou (UCLA)
DTSTART;VALUE=DATE-TIME:20211022T164000Z
DTEND;VALUE=DATE-TIME:20211022T172000Z
DTSTAMP;VALUE=DATE-TIME:20240329T044636Z
UID:BIRS-21w5154/34
DESCRIPTION:Title: Biophysics of X-inactivation and integration site T cell populations
in HIV-infected individuals\nby Tom Chou (UCLA) as part of BIRS works
hop Mathematics of the Cell: Integrating Signaling\, Transport and Mechani
cs\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BIRS-21w5154/34/
END:VEVENT
END:VCALENDAR