title: Multiscale diffusion in the mitotic Drosophila melanogaster syncytial blastoderm.
abstract: Despite the fundamental importance of diffusion for embryonic morphogen gradient formation in the early Drosophila melanogaster embryo, there remains controversy regarding both the extent and the rate of diffusion of well-characterized morphogens. Furthermore, the recent observation of diffusional "compartmentalization" has suggested that diffusion may in fact be nonideal and mediated by an as-yet-unidentified mechanism. Here, we characterize the effects of the geometry of the early syncytial Drosophila embryo on the effective diffusivity of cytoplasmic proteins. Our results demonstrate that the presence of transient mitotic membrane furrows results in a multiscale diffusion effect that has a significant impact on effective diffusion rates across the embryo. Using a combination of live-cell experiments and computational modeling, we characterize these effects and relate effective bulk diffusion rates to instantaneous diffusion coefficients throughout the syncytial blastoderm nuclear cycle phase of the early embryo. This multiscale effect may be related to the effect of interphase nuclei on effective diffusion, and thus we propose that an as-yet-unidentified role of syncytial membrane furrows is to temporally regulate bulk embryonic diffusion rates to balance the multiscale effect of interphase nuclei, which ultimately stabilizes the shapes of various morphogen gradients.
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Daniels
authors.forename: Richa
authors.initials: R
authors.lastname: Rikhy
authors.forename: Malte
authors.initials: M
authors.lastname: Renz
authors.forename: Terrence M
authors.initials: TM
authors.lastname: Dobrowsky
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
mesh_terms: D000465:Algorithms; D000818:Animals; D030801:Animals, Genetically Modified; D001756:Blastoderm / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism; D003198:Computer Simulation; D003593:Cytoplasm / Q000378:metabolism; D004058:Diffusion; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D015726:Giant Cells / Q000166:cytology / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008954:Models, Biological
chemical_list: D049452:Green Fluorescent Proteins