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An important substance in the signalling between individuals of Mucor-like fungi is trisporic acid (TA). This compound, together with some of its precursors, serves as a pheromone in mating between (+)- and (2)-mating types. Moreover, intermediates of the TA pathway are exchanged between the two mating partners. Based on differential equations, mathematical models of the synthesis pathways of TA in the two mating types of an idealised Mucor-fungus are here presented. These models include the positive feedback of TA on its own synthesis. The authors compare three sub-models in view of bistability, robustness and the reversibility of transitions. The proposed modelling study showed that, in a system where intermediates are exchanged, a reversible transition between the two stable steady states occurs, whereas an exchange of the end product leads to an irreversible transition. The reversible transition is physiologically favoured, because the highproduction state of TA must come to an end eventually. Moreover, the exchange of intermediates and TA is compared with the 3-way handshake widely used by computers linked in a network. [ABSTRACT FROM AUTHOR]

Genetic analysis of all Mucor-like fungi is severely impaired by the low efficiency of transformation systems and the genetic instability of the introduced plasmid constructs. The transformation efficiency of one of the model systems among mucoralean fungi, Absidia glauca, was improved considerably by microprojectile bombardment. For this purpose, a plasmid was constructed conferring (i) neomycin resistance as a selective marker and (ii) fluorescence due to expression of the gfp gene from the jellyfish Aequorea victoria. Compared with previous techniques, this method offers increased efficiency, with considerably easier handling than procedures based on protoplasts and, therefore, improved reliability. The uninucleate sporangiospores of A. glauca can be transformed early during the germination process. At this stage the number of nuclei ranges between 1 and 2. Thus, the abundance of transgenic nuclei in the coenocytic mycelia is high, and fewer problems are encountered with detecting low expression levels of the genes used for selection and monitoring of transformants. [ABSTRACT FROM AUTHOR]

Examines the specificity of polymerase chain reaction primers to the rape seed pathogen Leptosphaeria maculans. Differentiation of DNA bands between isolates; Determination of group-specificity pathogenicity; Use of chemical and dideoxynucleotide chain termination methods.

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Copyright of Journal of Phytopathology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)