Fig. 1. Expression of meu14⁺ and its paralogs during meiosis and structural comparison of their gene products. (A) The meu14⁺ gene is specifically transcribed during meiosis. Diploid h⁺/h^- (CD16-1) and h^-/h^- (CD16-5) cells were exposed to nitrogen starvation, which triggers meiosis in the former but not the latter strain, and cells were collected at 2 hour intervals for RNA extraction. Upper panels: Total RNA was blotted and probed by radiolabeled meu14⁺, mfp1⁺, mfp2⁺ and aro3⁺ DNA fragments. The intensities of the bands obtained by using the aro3⁺ probe and ethidium bromide staining were used as loading controls. Numbers at the bottom represent the cell populations harvested at each 2 hour interval and assessed for the percentages of cells that had four nuclei (counted after staining the cells with DAPI). (B) meu14⁺ gene expression is under the control of the sporulation-specific Mei4 transcription factor. Diploid h^-/h^- pat1-114/pat1-114 (JZ670) and h^-/h^- pat1-114 mei4 pat1-114 mei4 (AB4) cells were synchronized to enter the G1 phase by nitrogen starvation, and then induced to meiosis by temperature shift. Nitrogen was then added, and the cells were incubated at 34°C and collected at 2 hour intervals for RNA analysis as in panel A. (C) Structure of Meu14. (i) Conserved structural motifs. The coiled-coil region (C-C) is predicted using the COILS program with a 21-residue window setting (Lupas et al., 1991). (ii) Alignment of the predicted amino acid sequence of Meu14 with S. pombe and S. cerevisiae homologues. Homologous proteins were identified in a BLAST search using the protein sequence of Meu14. Hyphens represent gaps inserted to attain maximal homology. Amino acids identical to those in Meu14 are highlighted by a gray background. Amino acid numbers are denoted at the right-hand side of each sequence. The extended coiled-coil motif found in Meu14 is indicated by a solid line. (D) The phylogenetic tree of the Meu14 homologues. The tree was constructed based on the whole amino acid sequence of each protein by Genetyx-Mac software (Software Development, Tokyo, Japan) using the neighbor joining method (Saitou and Nei, 1987). The genomic DNA sequences used are recorded in the DDBJ/EMBL/GenBank database (accession nos. CAA97088, AAB68101, CAB16733 and CAA19279, respectively).