8 Results
for author "William K. Holloman"
Figure 1Cdc45 function is not required for teliospore germination. (A) The cdc45ts allele of U. maydis is due to a mutation at residue 303, which lies within a conserved region in the aligned Cdc45 orthologs (GenBank accession numbers indicated). Um (Ustilago maydis XP_761917); Cn (Cryptococcus neoformans AFR95427); Hs (Homo sapiens AAC67521); Cr (Chlamydamonas reinhardtii XP_001696501); Dm (Drosophila melanogaster AAD09003); Xl (Xenopus laevis AAC67520); Sc (Saccharomyces cerevisiae NP_013204). (B) cdc45ts mutant strain UCM266 and wild-type control plated at permissive and restrictive temperatures. (C) Teliospores obtained from a wild-type control or cdc45ts × cdc45ts cross were germinated at 22° for 24 hr or 32° for 16 hr and then stained with DAPI. (D) Promycelia, or germ tubes, emerging during teliospore germination were tallied.
Figure 2Formation of Nar+ recombinants during the course of infection. (A) The U. maydis life cycle is depicted schematically (adapted from Banuett and Herskowitz 1996) starting with mating of compatible haploids on the plant surface, proceeding in the plant through the switch to the dikaryon hyphal form, karyogamy, and the development and germination of teliospores. Forty 7-day-old seedlings were inoculated with freshly grown cultures of UCM350 and UCM520 and cultured under a daily light/dark cycle. At 2-day intervals, three to four plants were harvested, tumor tissue was excised and macerated, and aliquots of the suspension were plated on minimal media for selection of diploids and Nar+ recombinants as described in the Materials and Methods. (B) The bar graph indicates the frequency of Nar+ recombinant formation (solid bars) and the level of diploids (shaded bars) during the course of infection.
Figure 3spo11Δ aberrant meiosis. Teliospores issuing from crosses between wild type (UCM350 × UCM520) or spo11Δ (UCM738 × UCM762) were (A) germinated on YEPS medium for 54 hr. Colonies were washed off plates, resuspended, and vortexed in water to disperse cells. Aliquots (∼100 cells) were plated on (B) YEPS medium to display colony morphology of meiotic products; (C) charcoal-containing mating medium to reveal the fuz reaction indicating disomy at the b locus; (D) ammonium minimal medium with or without pantothenate and methionine to show non-Mendelian distribution of biosynthetic markers. (E) Cells (105 wild type or 107 spo11Δ) were spread on nitrate minimal with pantothenate and methionine to measure allelic recombination at nar1 as Nar+ prototrophs. (F) DNA content of individual isolated of spo11Δ meiotic progeny. Histograms indicate DNA content (x-axis), with 2C corresponding to G2 content of wildtype haploid control, and cell number (y-axis).