Contents - Max-Planck-Institut für Physik komplexer Systeme
Contents - Max-Planck-Institut für Physik komplexer Systeme
Contents - Max-Planck-Institut für Physik komplexer Systeme
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isdefinedbyaslow-downofcelldivisionasthecellsrepeatedlydivide,causedbyinheritanceofaging<br />
factorssuchasdamagedproteins. Weshowthatthecellsoffissionyeastdonotexhibitreplicative<br />
aging. Weperformedapedigreeanalysisofmicrocoloniesgrowingfromasinglecell. First,incontrast<br />
toobservationsinagingunicellularorganisms,slowlydividingmothercellsoffissionyeastdidnotgive<br />
risetoslowlydividingdaughtercells.Second,thefinalcelldivisionspriortocelldeath,whenreplicative<br />
agingshouldbemostpronouncedandthusdivisionslowest,werenotslowerthanaverage. Finally,no<br />
slow-downofdivisionwasobservedincellsthatrepeatedlyinheritedtheoldornewcellpoleformore<br />
than30divisions,oldornewspindlepolebody,alargerorasmallerpartofthecytoplasm. Moreover,<br />
damagedproteinsfromthemothercell,visualizedbyaGFP-taggedchaperoneHsp104,weredistributed<br />
randomlybetweenthedaughtercells.Togetherourresultssuggestthatafissionyeastcolonydoesnot<br />
accumulatedamageinalineageofcellsandthusdoesnotexhibitaging.Incontrasttomostorganisms,<br />
whichsegregatedamagetoagingcellsinordertoproduceoffspringwithhighreplicativepotential,fission<br />
yeastmaybefollowingadifferentlifestrategythatreliesonmaintenanceofthereplicativepotentialof<br />
allcells. Thishighlightsfissionyeastasapotentialcellularmodelforhumannon-agingcells,suchas<br />
cancer,germ,andstemcells.<br />
Cooperations<br />
FrankJülicher, mpipks:Modelingofnuclearoscillationsandcentering<br />
NenadPavin,UniversityofZagreb,Croatia,and mpipks:Modelingofnuclearoscillationsandcentering,<br />
searchforkinetochores<br />
ThiloGross, mpipks:Agingandproteinaggregationinsymmetricallydividingcells<br />
BenjaminLindner, mpipks:Searchforkinetochores<br />
StefanDiez,MPI-CBG,Dresden:Invitroreconstitutionofnuclearoscillations<br />
FrankBradke,MPIofNeurobiology,Martinsried:Theroleofcentrosomesinneuronalgrowth<br />
JurajGregan,UniversityofVienna:Tensiononmitoticchromosomes<br />
JuniorResearchGroup:MotorSystems<br />
(Head:Dr.StephanW.Grill)<br />
Ourgroupisinterestedinhowmolecularmachines,theworkhorsesofthecell,functioncollectivelyto<br />
giverisetothecomplexdynamicalprocessesobservedinlivingorganisms. Thewholeisgreaterthan<br />
thesumoftheparts. Inthisspiritwepursueanunderstandingofhowmolecularmechanismsgiverise<br />
tospecificbehaviorsthatemergeatlengthandtimescalesrelevantforprocessesatthecellbiological<br />
level,usingacombinedexperimentalandtheoreticalapproach.Themainfocusofourlabconcernsthe<br />
dynamicsoftheactomyosincytoskeletonanditsrelationtomolecularmechanisms.Wealsoinvestigate<br />
transcriptionofDNAintoRNAandtherelationtomoleculareventsthatoccurinthemachinerythatis<br />
involved.<br />
CytoskeletalSystems. Todate,systematicapproachesthatlinkphysicalmechanismsatthemolecular<br />
scaletoemergentbehavioursatthecellularscalearemissing. Webridgethisgap,andcombinetheory<br />
andexperimenttoinvestigatetheinterplaybetweencellularmechanicsandregulatorybiochemistryin<br />
thecontextofcellpolarizationinCaenorhabditiselegansembryos.<br />
Weareinterestedinhowtheactomyosincytoskeletonbehavesatacoarse-grainedandcell-scalelevel.We<br />
investigatethecellcortexintheonecellstageC.elegansembryo,whichundergoeslarge-scaleactomyosin<br />
corticalflowpriortoitsfirstmitosisinordertopolarizethecell. Wecharacterizecortexstructure<br />
anddynamicswithimagingtechniquesandwithbiophysicaltechniques,suchascorticallaserablation<br />
andquantitativephoto-bleachingexperiments. Wedevelopandemploynoveltheoreticalapproachesto<br />
describetheemergentcellscalemechanicalbehaviourintermsofanactivecomplexfluid. Finally,we<br />
utilizeapproachesfrommolecularbiologyandgeneticstounderstandhowtheseemergentmechanical<br />
propertiesareinfluencedbymolecularactivities.<br />
Aparticularfocusliesinapproachestounderstandtheinterplaybetweenregulatorybiochemistry,operatingthroughPARpolarityproteins,andcell-scalecytoskeletalmechanics.Weinvestigatethisinteraction,<br />
whichiscrucialtothedevelopmentofallanimals,bystudyingpatternformationinactivefluids.Here,<br />
activestressisregulatedbydiffusingmolecularcomponents.Nonhomogeneousactivestressprofilescreatepatternsofflowwhichtransportstressregulatorsbyadvection.Forexample,asinglediffusingspecies<br />
1.9. JuniorResearchGroups 33
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