Figure 3.

S. pombe cells carrying a deletion of the skb1 gene are aberrant in morphology and slightly defective for growth. (A) Map of the skb1 gene showing the fragment deleted by ura4 in construction of the skb1::ura4 mutant strain, SPSKB1U. The shaded bar corresponds to the sequence encoding the Skb1 protein; the open bar represents the skb1 sequence shown in Fig. 1. (B) Photomicrograph of wild-type (SP870) S. pombe cells. (C) Photomicrograph of skb1::ura4 (SPSKB1U) cells. Note that skb1::ura4 cells are less elongate than wild-type cells. (D) skb1::ura4 cells overexpressing shk1 from the plasmid pREP1Shk1. Cells were grown at 30°C in EMM to about 10⁷ cells per ml prior to photomicrography. (E) Growth curves for SPSKB1U cells transformed with pART1Skb1, for expression of Skb1 (○), and pART1 (•). S. pombe cells carrying the skb1 deletion exhibit a slower growth rate than skb1⁺ cells. (F) Wild-type (SP870) S. pombe cells overexpressing Skb1 from the plasmid pREP1. Note that cells are abnormally elongate in morphology, compared with control cells in B.