TY - JOUR
T1 - The effects of ropy-1 mutation on cytoplasmic organization and intracellular motility in mature hyphae of Neurospora crassa
AU - Riquelme, Meritxell
AU - Roberson, Robert
AU - McDaniel, Dennis P.
AU - Bartnicki-García, Salomón
N1 - Funding Information:
Research at UC Riverside was supported in part by University resources and resources accumulated during the many years when the NIH and the NSF provided SBG with generous grant support, the most recent being GM-48257 and IBN-9204541 respectively. This work was initially supported by a Graduate Dean’s Dissertation Research Grant from the University of California, Riverside to MR. Research at ASU was supported by the Plant Biology Department. Standard epifluorescence and LSCM were performed in the W.M. Keck Bioimaging Laboratory (ASU). Electron microscopy was performed in the Life Sciences Electron Microscopy Facility (ASU).
PY - 2002
Y1 - 2002
N2 - We have used light and electron microscopy to document the cytoplasmic effects of the ropy (ro-1) mutation in mature hyphae of Neurospora crassa and to better understand the role(s) of dynein during hyphal tip growth. Based on video-enhanced DIC light microscopy, the mature, growing hyphae of N. crassa wild type could be divided into four regions according to cytoplasmic organization and behavior: the apical region (I) and three subapical regions (II, III, and IV). A well-defined Spitzenkörper dominated the cytoplasm of region I. In region II, vesicles (∼0.48 μm diameter) and mitochondria maintained primarily a constant location within the advancing cytoplasm. This region was typically void of nuclei. Vesicles exhibited anterograde and retrograde motility in regions III and IV and followed generally parallel paths along the longitudinal axis of the cell. A small population of mitochondria displayed rapid anterograde and retrograde movements, while most maintained a constant position in the advancing cytoplasm in regions III and IV. Many nuclei occupied the cytoplasm of regions III and IV. In ro-1 hyphae, discrete cytoplasmic regions were not recognized and the motility and/or positioning of vesicles, mitochondria, and nuclei were altered to varying degrees, relative to the wild type cells. Immunofluorescence microscopy revealed that the microtubule cytoskeleton was severely disrupted in ro-1 cells. Transmission electron microscopy of cryofixed cells confirmed that region I of wild-type hyphae contained a Spitzenkörper composed of an aggregation of small apical vesicles that surrounded entirely or partially a central core composed, in part, of microvesicles embedded in a dense granular to fibrillar matrix. The apex of ro-1 the hypha contained a Spitzenkörper with reduced numbers of apical vesicles but maintained a defined central core. Clearly, dynein deficiency in the mutant caused profound perturbation in microtubule organization and function and, consequently, organelle dynamics and positioning. These perturbations impact negatively on the organization and stability of the Spitzenkörper, which, in turn, led to severe reduction in growth rate and altered hyphal morphology.
AB - We have used light and electron microscopy to document the cytoplasmic effects of the ropy (ro-1) mutation in mature hyphae of Neurospora crassa and to better understand the role(s) of dynein during hyphal tip growth. Based on video-enhanced DIC light microscopy, the mature, growing hyphae of N. crassa wild type could be divided into four regions according to cytoplasmic organization and behavior: the apical region (I) and three subapical regions (II, III, and IV). A well-defined Spitzenkörper dominated the cytoplasm of region I. In region II, vesicles (∼0.48 μm diameter) and mitochondria maintained primarily a constant location within the advancing cytoplasm. This region was typically void of nuclei. Vesicles exhibited anterograde and retrograde motility in regions III and IV and followed generally parallel paths along the longitudinal axis of the cell. A small population of mitochondria displayed rapid anterograde and retrograde movements, while most maintained a constant position in the advancing cytoplasm in regions III and IV. Many nuclei occupied the cytoplasm of regions III and IV. In ro-1 hyphae, discrete cytoplasmic regions were not recognized and the motility and/or positioning of vesicles, mitochondria, and nuclei were altered to varying degrees, relative to the wild type cells. Immunofluorescence microscopy revealed that the microtubule cytoskeleton was severely disrupted in ro-1 cells. Transmission electron microscopy of cryofixed cells confirmed that region I of wild-type hyphae contained a Spitzenkörper composed of an aggregation of small apical vesicles that surrounded entirely or partially a central core composed, in part, of microvesicles embedded in a dense granular to fibrillar matrix. The apex of ro-1 the hypha contained a Spitzenkörper with reduced numbers of apical vesicles but maintained a defined central core. Clearly, dynein deficiency in the mutant caused profound perturbation in microtubule organization and function and, consequently, organelle dynamics and positioning. These perturbations impact negatively on the organization and stability of the Spitzenkörper, which, in turn, led to severe reduction in growth rate and altered hyphal morphology.
KW - Dynein
KW - Laser scanning confocal microscopy
KW - Microtubules
KW - Neurospora crassa
KW - Ropy
KW - Spitzenkörper
KW - Ultrastructure
KW - Video-enhanced light microscopy
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UR - http://www.scopus.com/inward/citedby.url?scp=0036430483&partnerID=8YFLogxK
U2 - 10.1016/S1087-1845(02)00506-6
DO - 10.1016/S1087-1845(02)00506-6
M3 - Article
C2 - 12409101
AN - SCOPUS:0036430483
SN - 1087-1845
VL - 37
SP - 171
EP - 179
JO - Fungal Genetics and Biology
JF - Fungal Genetics and Biology
IS - 2
ER -