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Group3 medulloblastoma (MBG3) that predominantly occur in young children are usually associated with MYC amplification and/or overexpression, frequent metastasis and a dismal prognosis. Physiologically relevant MBG3models are currently lacking, making inferences related to their cellular origin thus far limited. Using in utero electroporation, we here report that MBG3mouse models can be developed in situ from different multipotent embryonic cerebellar progenitor cells via conditional expression of Myc and loss of Trp53 function in several Cre driver mouse lines. The Blbp-Cre driver that targets embryonic neural progenitors induced tumors exhibiting a large-cell/anaplastic histopathology adjacent to the fourth ventricle, recapitulating human MBG3. Enforced co-expression of luciferase together with Myc and a dominant-negative form of Trp53 revealed that GABAergic neuronal progenitors as well as cerebellar granule cells give rise to MBG3with their distinct growth kinetics. Cross-species gene expression analysis revealed that these novel MBG3models shared molecular characteristics with human MBG3, irrespective of their cellular origin. We here developed MBG3mouse models in their physiological environment and we show that oncogenic insults drive this MB subgroup in different cerebellar lineages rather than in a specific cell of origin.

Seven new iridabenzenes were prepared by the addition of (Z)-1,2-diphenyl-3-(2-lithioethenyl)-1-cyclopropene to the Vaska-type complexes [IrCl(CO)(PR3)2], containing differing phosphine ligands. The iridabenzenes could be isolated from the reaction mixture either by direct means or after heating of the crude solution. In the case of the reactions using PMe3 and PEt3, a σ-vinyl/η²-cyclopropene Ir(I) complex, best described as an iridabenzvalene, could be isolated and fully characterized. The metallabenzvalene intermediate could be cleanly converted to the corresponding iridabenzene by heating in solution. The PEt3-substituted iridabenzene and iridabenzvalene were characterized by X-ray crystallography. Plausible mechanisms for the formation of both iridacycles from the lithiated vinylcyclopropene as well as the isomerization of the benzvalene into the benzene are postulated.

All pith samples from 68 dead saguaro cacti in 3 plots and 11 isolated dead plants in Saguaro National Monument, Arizona, produced at least one species of myxomycete upon incubation at 20 or 30°C. Three species,Badhamia gracilis (Macbr.) Macbr.,Physarum straminipes Lister, andDidymium eremophilum M. Blackwell et Gilbertson, developed at high frequencies on the substrates in moist chamber culture.Perichaena corticalis (Batsch) Rost, andProtophysarum phloiogenum M. Blackwell et Alexopoulos were also present. Although previous literature reports [9] indicated that Myxomycetes grow best at low pH, these species all tolerated substrates of pH 8.7–10.4.Didymium eremophilum andP. phloiogenum had peaks in sporulation within 6 days; other species were slower. There was no difference in time of sporulation ofB. gracilis orD. eremophilum at 20 and 30°C; however, sporulation ofP. straminipes was significantly later at 30°C. Reduced spore germination and slower buildup of critically sized amoebal populations ofP. straminipes at 30°C may be a factor.

Most whitefly-transmitted geminiviruses possess bipartite DNA genomes, and this feature may facilitate viral evolution through pseudorecombination and/or recombination. To test this hypothesis, the DNA-A and DNA-B components of the geminiviruses bean dwarf mosaic virus (BDMV) and tomato mottle virus (ToMoV) were exchanged, and the resultant pseudorecombinants were serially passaged through plants. Both pseudorecombinants were infectious in Nicotiana benthamiana but induced attenuated symptoms and had reduced DNA-B levels. Serial passage experiments revealed that the BDMV DNA-A plus ToMoV DNA-B pseudorecombinant could not be maintained beyond three passages. In contrast, the ToMoV DNA-A plus BDMV DNA-B pseudorecombinant was maintained during serial passage through N. benthamiana and Phaseolus vulgaris and, after three to five passages, became highly pathogenic. Furthermore, the increased pathogenicity of this pseudorecombinant was consistently associated with an increased level of DNA-B, which eventuated in equivalent levels of both components. Sequence analysis of the DNA-B component of the more pathogenic pseudorecombinant revealed that intermolecular recombination had taken place in which most of the BDMV DNA-B common region was replaced with the ToMoV DNA-A common region. This recombinant DNA-B component, which contained the ToMoV origin of replication, was the predominant DNA-B component associated with the more pathogenic pseudorecombinant. These results provide the first demonstration of recombination between distinct bipartite geminiviruses and establish that the bipartite genome can facilitate viral evolution through pseudorecombination and intermolecular recombination.

A restriction fragment length polymorphism (RFLP)-based linkage map for common bean (Phaseolus vulgaris L.) covering 827 centiMorgans (cM) was developed based on a F2 mapping population derived from a cross between BAT93 and Jalo EEP558. The parental genotypes were chosen because they exhibited differences in evolutionary origin, allozymes, phaseolin type, and for several agronomic traits. The segregation of 152 markers was analyzed, including 115 RFLP loci, 7 isozyme loci, 8 random amplified polymorphic DNA (RAPD) marker loci, and 19 loci corresponding to 15 clones of known genes, 1 virus resistance gene, 1 flower color gene, and 1 seed color pattern gene. Using MAPMAKER and LINKAGE-1, we were able to assign 143 markers to 15 linkage groups, whereas 9 markers remained unassigned. The average interval between markers was 6.5 cM; only one interval was larger than 30 cM. A small fraction (9%) of the markers deviated significantly from the expected Mendelian ratios (1:2:1 or 3:1) and mapped into four clusters. Probes of known genes belonged to three categories: seed proteins, pathogen response genes, and Rhizobium response genes. Within each category, sequences homologous to the various probes were unlinked. The I gene for bean common mosaic virus resistance is the first disease resistance gene to be located on the common bean genetic linkage map.

Alternative genes for resistance to Bean Common Mosaic Virus in common bean (Phaseolus vulgarisL.) are necessary as a result of the recent introduction of necrasis‐inducing strains of this virus into the USA. The recessive bc‐3gene confers resistance against all known strains of this pathogen. We describe here experiments to develop a relatively easy‐to‐use procedure to introgress the bc‐3gene into elite bean cultivars. First, we employedb ulked segregant analysis to identify RAPD markers linked to the bc‐3locus. The ROCII/350/420 marker was codominant with the bc‐3gene and the ROC20/460 marker was dominant and linked in trans. A survey of cultivated materials allowed us to identify the likely evolutionary origin of the bc‐3resistance allele as a member of the Mesoameriean gene pool, probably of race Mesoamerica. Polymorphism of the RAPD markers in a Davis common bean mapping population (BAT93 ✕ Jalo EEP558) allowed us to map the markers and, by inference, the bc‐3gene to linkage group D6. Second, we used sequence information from the cloned RAPD fragments to design longer, more reliable PCR primers that differentiate individuals homozygous for the resistance allele from susceptible genotypes in segregating populations of Andean origin. Third, we developed a marker tagging system that used a simplified DNAe xtraction technique and a PCR‐based assay to identify the genotype of common bean plants at the bc‐3disease resistance locus. This simplified marker assisted selection system is expected to eliminate the need for costly quarantines and progeny tests in breeding programs for common be an of Andean origin.

Coniophora eremophila and Antrodia sinuosa cause brown heartrot in living lemon trees in southern Arizona and California. They can be distinguished in the field by differences in rot characteristics. Both have a high optimum growth temperature of approximately 35°C. Coniophora eremophila has a cultural morphology typical of other Coniophora species and did not fruit in culture. Antrodia sinuosa cultures were morphologically similar to previous reports and fruited readily under laboratory conditions. Mating tests with homokaryotic single spore isolates showed it to have a heterothallic bipolar mating system. The decay capacity of C. eremophila on lemon wood test blocks under laboratory conditions was low compared to that of A. sinuosa, five other brown rot fungi, and three white rot fungi.

Treatment of nitrile 1 with an equimolar amount of DIBAL produces the alane complex [(1,2,3-(t-Bu)3-cyclo-C3)CH&dbd;NAl(i-Bu)2]2 (3), which reacts sluggishly with protic nucleophiles. The X-ray crystal structure of 3 shows unusual geometric distortions in the Al2N2 core and about the imine carbon, as well as in the cyclopropene ring, all of which are attributed to the extreme steric bulk of the hydrocarbon ligands.

The asparagus miner, Ophiomyia simplex (Loew), is well established on western Massachusetts asparagus. Adults emerged in late spring and mated, and females oviposited on ferns of wild and 1- and 2-year-old volunteer asparagus plants, Asparagus officinalis L. First- and second-generation adults were active in commercial asparagus fields when plants went to fern after harvest. O. simplex has been shown to facilitate inoculum build-up and disease increase of asparagus stem, crown, and root rot caused by Fusarium moniliforme Sheldon and F. oxysporum Schlecht. Larval mining predisposed plants to upper stalk infections. Contaminated pupae and puparia on above-ground stalks were fungal inoculum sources and overwintered both pathogens, contaminating adults with fungal spores. Cultural and insecticidal control strategies for managing the asparagus miner are considered as a means to reduce larval damage and Fusarium disease incidence.

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