Expression and localization of Bqt3 and -4. (A) Two-hybrid interaction of Bqt3 and -4. AD and BD indicate the constructs based on the pGADT7 and pGBKT7 plasmids, respectively (see Materials and methods). (B) Localization of GFP-Bqt4 (green) and mCherry-Bqt3 (red) in vegetatively growing cells. The observed strain is CRLt53 (h⁹⁰ bqt3Δ::LEU2, bqt4Δ::ura4⁺, aur1::mCherry-bqt3, lys1::GFP-bqt4). (C) bqt3⁺ and -4⁺ genes were expressed in vegetatively growing cells. Relative levels of expression were determined by real-time PCR, under which the expression of cdc2⁺ was normalized to 100 as a standard. The mean of two experiments is shown. (D) The expression profiles of Bqt3 and -4 upon nitrogen starvation and mating pheromone (P-factor) treatment analyzed by DNA microarray experiments (as described in Chikashige et al. [2006]). Blue indicates nitrogen starvation. Red indicates P-factor treatment with nitrogen starvation. The vertical axis is the expression ratio relative to the vegetative level on a base 2 logarithmic scale, as described in Chikashige et al. (2006). The ratio of the expression levels of each gene is plotted for each time point (hours) after nitrogen starvation. (E) Localization of GFP-Bqt3 (green) and Taz1-mCherry (red) in a meiotic cell. The observed strain is CRLt73 (h⁹⁰ aur1::GFP-bqt3, taz1-mCherry::kan). (F) Live observation of cells expressing GFP-Bqt4 in meiosis. The strain observed is CRLs53 (h⁹⁰ bqt4Δ::ura4⁺, lys1::GFP-bqt4, taz1-mCherry::kan). Selected frames of time-lapse images are shown. The image at each time point is a projection of optical section images. Aggregates of Bqt4 often appear on the nuclear membranes. These aggregates sporadically detach from the trailing edge of the moving nucleus, as shown in Video 1. Numbers on the left of each image indicate the time in minutes. Bars, 10 µm.