Nuclear shape and size are cell-type specific. Change in nuclear shape is seen during cell division, development and pathology. The nucleus of Saccharomyces cerevisiae is spherical in interphase and becomes dumbbell shaped during mitotic division to facilitate the transfer of one nucleus to the daughter cell. Because yeast cells undergo closed mitosis, the nuclear envelope remains intact throughout the cell cycle. The pathways that regulate nuclear shape are not well characterized. The nucleus is organized into various subcompartments, with the nucleolus being the most prominent. We have conducted a candidate-based genetic screen for nuclear shape abnormalities in S. cerevisiae to ask whether the nucleolus influences nuclear shape. We find that increasing nucleolar volume triggers a non-isometric nuclear envelope expansion resulting in an abnormal nuclear envelope shape. We further show that the tethering of rDNA to the nuclear envelope is required for the appearance of these extensions.

核形状和大小是细胞类型特异性的。在细胞分裂、发育和病理过程中可以看到核形状的变化。酿酒 酵母的细胞核在分裂间期是球形的，在有丝分裂期间变成哑铃形，以利于一个细胞核转移到子细胞。由于酵母细胞经历闭合有丝分裂，核膜在整个细胞周期中保持完整。调节核形状的途径尚未得到很好的表征。细胞核分为不同的亚区室，其中核仁最为突出。我们对酿酒酵母的核形状异常进行了基于候选的遗传筛查，以了解核仁是否影响核形状。我们发现，核仁体积的增加会引发非等距核膜扩张，导致核膜形状异常。我们进一步表明，rDNA 与核膜的束缚是这些延伸的出现所必需的。