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Genetics in Sordaria fimicola and arrangement of ascopores

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Genetics in Sordaria fimicola and arrangement of ascopores

Postby MikeJ » Mon Feb 02, 2009 2:04 pm

Hi guys,

I encountered an interesting result which puzzled my demonstrator and I, during one of the introductory practicals for a Genes module I'm studying and I was hoping someone may be able to explain what happened (because I sure as hell can't!). During the practical we looked at S.fimicola and the mutant strains which produce light coloured ascospores ('hyaline' mutants). We observed crossed perithecia, and then looked at asci under light microscopes in order to deduce the events that occured during meiosis.

One of the asci we observed had eight ascopores which went in the following order (h = mutant, + = wild type): h + h + h + h +. I was wondering if anyone could shed some light on how such an arrangement could happen? From a genetics point of view, I just can't see how this can happen at all (so I'm hesitant to post in this forum at all!). My knowledge of ascus formation is non-existent so I'm not sure if this could even occur, but the only way I can see how this could happen is if two independent 'switches' happened, so that there was an initial arrangement of hh++hh++ but the 2+3rd ascopores switched (i.e. to form a h+h+ arrangement) and then the same happened with the 6+7th ascopores. Although, admittedly, even if this were possible, it seems unlikely. :?
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Postby JorgeLobo » Thu Feb 05, 2009 6:16 pm

Could understand hhhh++++ or hh++hh++ with ross over but wouldn't expect that either. Almost as if a second stage ("switch") cross-over event took place. This was but on ascus - have you reproduced this?
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