The effect of the strong promoter from the alcohol dehydrogenase gene on mitotic and meiotic intragenic recombination has been studied at the ade6 locus of the fission yeast Schizosaccharomyces pombe. A 700-bp fragment containing the functional adhi promoter was used to replace the weak wild-type promoter of the ade6 gene. Analysis of mRNA showed that strains with this ade6::adhl fusion construct had strongly elevated ade6-specific mRNA levels during vegetative growth as well as in meiosis. These increased levels of mRNA correlated with a 20-to 25-fold stimulation of intragenic recombination in meiosis and a 7-fold increased prototroph formation during vegetative growth. Analysis of flanking marker configurations of prototrophic recombinants indicated that simple conversions as well as conversions associated with crossing over were stimulated in meiosis. The strongest stimulation of recombination was observed when the adhl promoter was homozygous. Studies with heterologous promoter configurations revealed that the highly transcribed allele was the preferred acceptor of genetic information. The effect of the recombinational hot spot mutation ade6-M26 was also investigated in this system. Its effect was only partly additive to the elevated recombination rate generated by the ade6::adhl fusion construct.The mechanisms of genetic recombination have been investigated in great detail in the last few years. Although much information has been collected and several models for recombination have been proposed (e.g., references 26, 27, 31, 32, and 40), the mechanisms are not yet fully understood. However, it has become clear that several aspects of DNA metabolism, such as DNA repair and transcription, are closely interrelated with recombination.Transcription and recombination studies have been done particularly in eucaryotes. The results show that recombination between segments of the immunoglobulin heavy-chain locus is accompanied by transcription. A role in targeting of the recombination events has been proposed for this activity (3,46,47). In addition, recombination between adenovirus DNA and hamster, mouse, or human cell DNA is also found to occur at transcriptionally active regions. It was proposed that transcription establishes a chromatin configuration which is more accessible to foreign DNA and for the recombination machinery (35).In the budding yeast Saccharomyces cerevisiae, several systems that show a correlation between transcription and recombination have been reported. Mating-type switching occurs via a double-strand break which is induced by the HO endonuclease only in the expressed cassette of the matingtype locus (38). However, if the two remaining mating-type cassettes that are normally transcriptionally silent become expressed as the result of a mutation in one of the four SIR genes (18, 21), they too serve as recipients for the HOinduced double-strand cut (20). Recently it has been shown that the SIR2 gene not only is involved in the control of expression of the mating-type system but also represses bot...

Most social animals depend on group decisions for coordination. Recent models suggest that the level of interindividual conflict strongly influences whether groups reach a consensus during decision making. However, few experimental studies have explored how wild animals make group decisions in situations with conflicting interests. Such experimental data are particularly lacking for animal societies with regular fission and fusion of subgroups. In this long-term study, we varied the level of conflict of interest among members of three wild Bechstein's bat (Myotis bechsteinii) colonies with high fission-fusion dynamics experimentally to explore whether the bats adapt their group decisions about communal roosts accordingly. In situations with low levels of conflict of interest, a minority of bats experiencing a roost as suitable was sufficient for a group consensus to use it communally. In contrast, if their interests diverged strongly, the bats no longer sought a compromise, but based their roosting decisions on individual preferences instead. Our results demonstrate that the rules applied to make group decisions can vary with the level of conflict among the individual interests of group members. Our findings are in agreement with predictions of the models and provide evidence for highly flexible group decisions within species.

The effect of the strong promoter from the alcohol dehydrogenase gene on mitotic and meiotic intragenic recombination has been studied at the ade6 locus of the fission yeast Schizosaccharomyces pombe. A 700-bp fragment containing the functional adh1 promoter was used to replace the weak wild-type promoter of the ade6 gene. Analysis of mRNA showed that strains with this ade6::adh1 fusion construct had strongly elevated ade6-specific mRNA levels during vegetative growth as well as in meiosis. These increased levels of mRNA correlated with a 20- to 25-fold stimulation of intragenic recombination in meiosis and a 7-fold increased prototroph formation during vegetative growth. Analysis of flanking marker configurations of prototrophic recombinants indicated that simple conversions as well as conversions associated with crossing over were stimulated in meiosis. The strongest stimulation of recombination was observed when the adh1 promoter was homozygous. Studies with heterologous promoter configurations revealed that the highly transcribed allele was the preferred acceptor of genetic information. The effect of the recombinational hot spot mutation ade6-M26 was also investigated in this system. Its effect was only partly additive to the elevated recombination rate generated by the ade6::adh1 fusion construct.

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Cyclohexane derivatives Q 0040 Diastereoselectivity Control of the Radical Carboazidation of Substituted Methylenecyclohexanes. -The nature and position of the substituents influence the stereoselective outcome of the title reaction. The introduction of bulky or axial groups at position 2 allows highly stereoselective carboazidation. -(CREN, S.; SCHAER, P.; RENAUD*, P.; SCHENK, K.; J. Org. Chem. 74 (2009) 8, 2942-2946; Inst. Chem. Biochem., Univ. Bern, CH-3012 Bern, Switz.; Eng.) -Jannicke 35-063