Tubulovesicular processes emerge from trans-Golgi cisternae, extend along microtubules, and interlink adjacent trans-golgi elements into a reticulum.
Morphological dynamics and membrane transport within the living Golgi apparatus of astrocytes labeled with NBD-ceramide were imaged using both electronically enhanced fluorescence video and laser confocal microscopy. In time-lapse recordings, continuous tubulovesicular processes are observed to emerge from trans-Golgi elements and extend along microtubules at average rates of 0.4 microns/s. In addition, discrete fluorescent particles are observed to emerge from the trans-Golgi and subsequently migrate along microtubules at comparable velocities. Frequently, tubulovesicular processes form stable connections that interlink adjacent trans-Golgi elements into an extensive reticulum. Laser photobleaching-recovery experiments reveal that tubulovesicular processes can provide direct pathways for the diffusion of membrane lipids between joined trans-Golgi elements. These results suggest that microtubule-based transport and membrane fusion can operate to interconnect certain cisternal membranes of adjacent Golgi elements within the cell.
Cooper
M S
MS
Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510.
Cornell-Bell
A H
AH
Chernjavsky
A
A
Dani
J W
JW
Smith
S J
SJ
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000648:ultrastructure*; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D006056:Golgi Apparatus / Q000648:ultrastructure*; D006624:Hippocampus / Q000166:cytology; D007834:Lasers; D008853:Microscopy / Q000379:methods; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000648:ultrastructure*; D015388:Organelles / Q000648:ultrastructure*; D011712:Pyramidal Tracts / Q000166:cytology; D051381:Rats; D013997:Time Factors; D014404:Tubulin / Q000032:analysis; D014741:Video Recording
D005456:Fluorescent Dyes; D014404:Tubulin