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Apoptotic cell death was shown to be accompanied or preceded by an elevated expression of the c-fos protooncogene and DNA binding activity of transcription factor AP-1. We used Fos-deficient mice to study the role of c-Fos during programmed cell death in the prostate. In normal mice apoptosis is induced in the prostate within 2-4 days after castration. Histological features of reduced secretory activity and morphological signs of programmed cell death become obvious. No apparent decrease in secretory activity and no epithelial cell death were observed in Fos-deficient animals after castration. Fragmentation of nuclear DNA was measured by in situ terminal transferase reaction. DNA fragmentation was observed in the prostate epithelium of control mice after castration whereas no similar fragmentation was found in Fos-deficient animals. After castration an AP-1 complex accumulated in the prostate of Fos deficient mice which mainly consists of FosB, Fra-2 and JunD whereas in control animals the AP-1 complex in addition contained c-Fos. Our data strongly suggest that c-Fos is required for programmed cell death of prostate epithelial cells.

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RESUMEN

Isolate WELA of the plant pathogenic oomycete fungus Peronospora parasitica causes downy mildew in the Arabidopsis thaliana ecotypes Weiningen (Wei-0) and La-er, whereas ecotypes RLD and Col-0 are resistant. Genetic crosses between resistant RLD and susceptible Wei-0 showed that resistance was inherited in a simple Mendelian fashion as a monogenic dominant trait. The interactions between different isolates of P. parasitica and ecotypes of A. thaliana show race-specific variation and fit a gene-for-gene relationship. The RPP11 resistance gene was mapped by following the co-segregation of the resistance phenotype with RFLP markers in a mapping population of 254 F3 families derived from RLD x Wei-0 F2 individuals. Linkage analysis using version 1.9 of the MAPMAKER program placed the RPP11 resistance locus on chromosome III between marker m249 (two recombinants) and marker g2534 (six recombinants). Markers g2534 and g4117 are on YAC EG7H1. Marker g4117 and one end probe (N5) generated from YAC EG7H1 showed no recombinants. The YAC end probe N5, which was generated by plasmid rescue, was used to screen clones in the Eric Ward YAC library and a YAC was fished (EW19B12) which also hybridised with m249. Thus, a YAC contig has been established over the region where the resistance locus maps. Because the YACs were made with ecotype Columbia DNA it is necessary to isolate the equivalent region from RLD in order to clone the resistance locus. To this end a phage λ-DASH (™) genomic library was prepared from RLD and a contig covering the relevant region of the YACs is currently under construction.

RESUMEN

Potato (Solanum tuberosum L. cv. Datura) contains approximately 40-50 phenylalanine ammonia-lyase (PAL) genes/haploid genome. Considerable cDNA heterogeneity indicates that at least about 10, and probably more, of these genes are potentially active. One subfamily, represented by one selected member (PAL-1), was analyzed with respect to genomic complexity, nucleotide and deduced amino acid sequence, and mode of constitutive or induced expression. For comparison, a second gene (PAL-2), representing several subfamilies that are easily distinguished from PAL-1, was included in these studies. Extensive structural similarities were observed both between the TATA-proximal portions of the PAL-1 and PAL-2 promoters, particularly in the areas containing putative cis-acting elements, and among all presently known PAL proteins from various higher and lower plants. The relative abundance of PAL mRNA varied greatly in several major potato organs. However, the patterns obtained with probes detecting either total PAL mRNA or more specifically, PAL-1-related or PAL-2-related mRNA species, were the same within experimental error. Mature leaves contained particularly low levels of PAL mRNA. Infection of these leaves with the pathogenic fungus, Phytophthora infestans, resulted in a large, transient induction of PAL mRNA. The relative timing of PAL-1 and PAL-2 mRNA expression, however, differed in compatible (fungus virulent, plant susceptible) but not in incompatible interactions (fungus avirulent, plant resistant). Wounding of leaves caused an extremely rapid and transient induction of both PAL mRNA species.

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