FIG. 8.

esa1 mutants have aberrant ultrastructural morphology. Wild-type ESA1 (LPY3498) (A and B) and esa1-L254P (LPY3500) (C and D) cells were incubated at 37°C for 4 h and prepared by rapid freezing for electron microscopy. In wild-type cells, the nucleolar electron-dense material was at both poles of the dividing nucleus (n) (A) or in a crescent shape in a nondividing cell (B, closed arrowhead). However, in the esa1 mutant (C and D, open arrowheads), the electron-dense material was dispersed throughout the nucleus. The majority of the mutant large-budded cells showed the nucleus on one side of the bud neck, in contrast to wild-type cells, where the nucleus extended equally through the bud neck. The cytoplasm of the esa1 mutant (C, asterisk) was also more highly vesiculated than in wild-type cells. Each panel shows a different cell, and scale bars shown represent 1 μm (A and C) and 0.5 μm (B and D). v, vacuoles.