title: Amyloplast sedimentation and organelle saltation in living corn columella cells.
abstract: Amyloplast sedimentation during gravistimulation and organelle movements was studied in living central rootcap cells of Zea mays L. cv. Merit.  Cells from sectioned roots were viewed with a horizontally-mounted videomicroscope.  The kinetics of gravity-induced amyloplast sedimentation were comparable to those calculated from experiments using fixed material.  Individual amyloplasts fell at an average velocity of 5.5 micrometers min-1; the maximal velocity of fall measured was 18.0 micrometers min-1.  Amyloplasts often rotated, sometimes rose in the cytoplasm, and occasionally underwent sudden rapid movements as fast as 58 micrometers min-1.  Saltations of other organelles were frequently observed.  This appears to be the first report of cytoplasmic streaming in the presumptive statocytes of roots.
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853, USA.
authors.forename: F D
authors.initials: FD
authors.lastname: Sack
authors.forename: M M
authors.initials: MM
authors.lastname: Suyemoto
authors.forename: A C
authors.initials: AC
authors.lastname: Leopold
mesh_terms: D003595:Cytoplasmic Streaming / Q000502:physiology; D006112:Gravitation; D018466:Gravity Sensing / Q000502:physiology; D008854:Microscopy, Electron; D015388:Organelles / Q000502:physiology*; D018518:Plant Root Cap / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure*; D018087:Plastids / Q000502:physiology*; D003313:Zea mays / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure