Colonial development in Pandorina morum: I. Structure and composition of the extracellular matrix

摘要

EverycellinacolonyofthefreshwateralgaPandorinamorumproducesadaughtercolonyineachroundofvegetativereproduction.ThecellsofP.morumstructurallyresemblethoseofChlamydomonasanddonotobviouslydifferfromtheirpresumptiveunicellularancestorinwaysthatwouldaccountfortheircolonialstate.Itisthereforepossiblethattheircolonialassociationmaybetheresultofalteredextracellularmatrix,intercellularconnections,ormodifiedprocessesofcelldivisionandmatrixformation.TheultrastructuralstudiesandchemicalanalysisreportedhereshowthatthematrixofP.morumisamultilayeredstructurecontaininghydroxyproline-richglycoproteinsandsulfatedpolysaccharide.Significantly,thismatrixdisplaysnomajordifferencesfromthea€?walla€?ofChlamydomonasspecies.Nointercellularconnectionshavebeenfoundinmaturecolonies.Theextracellularmatrixthereforemaintains,butdoesnotinitiate,thecolonialarrangementofthecells.