The snxA1 and nim A5 mutations of Aspergillus nidulans Interact to Affect M itotic Spindle Structure.

R. Day, B. Fontenelle, S. Chandna, and S.L. McGuire,

Author address: 

Millsaps College, Jackson, MS, USA


The snxA gene interacts with NIMX cdc2 to affect mitosis, and its mutation causes abnormal nuclear morphology at 17C, while the nimA gene affects the nuclear import of NIMX cdc2 and when mutated blocks mitotic entry at 42C. To characterize the effects of the snxA1 mutation on microtubule and nuclear structure, strains expressing a GFP-tubA (alpha-tubulin) gene were generated with either snxA1 or nimA5 mutations alone or with a snxA1/nimA5 double mutant. At 17C snxA1/GFP-tubA cells had severe nuclear defects, thickened hyphae, abnormal spindle structures, and abnormal interphase microtubule arrays. Mitotic spindles were highly variable in length. Some spindles had no nuclei attached to them, while yet others were bifurcated or trifurcated and had fragmented, variably condensed nuclei along their lengths. Similar abnormal nuclei and spindle structures were observed when snxA1/nimA5 strains were germinated at 32C and upshifted to 42C for 3 hours. Additionally, snxA1 was shown to suppress a checkpoint defect observed in nimA5 cells: Double mutants were able to grow in the presence of 20mM hydroxyurea, while nimA5 cells were sensitive at 10mM hydroxyurea. Cloning and further characterization of the snxA gene will provide clues to the interactions of NIMXCDC2, NIMA, SNXA, and the regulation of mitotic spindle formation. Supported by NIHGM55885-03 and the Mississippi Functional Genomics Network.

abstract No: 


Full conference title: 

23rd Fungal Genetics Conference
    • Fungal Genetics Conference 23rd (2002)