Recombinant inbred mapping of a ubiquitin fusion protein gene
--Dan Maillet, Burr Atkinson and David B. Walden

In this communication we describe the mapping of a specific ubiquitin fusion protein gene, MubG7. Inspection of the genomic sequences obtained for two Oh43 ubiquitin fusion-protein genes indicated that the nucleotide sequence 5' to the open reading frame in these genes share little identity (approximately 30%; see Liu et. al., this Newsletter). We excised a 2.0kb, 5'-DNA fragment, designated as scMubG7-J, with EcoRI/XbaI from a 6.2kb insert in a genomic clone containing MubG7, and assessed the specificity of the fragment by Southern blot hybridization analysis. These analyses confirmed that this DNA fragment recognizes a single copy ubiquitin fusion-protein gene and, therefore, this DNA fragment was used to map this gene in maize.

Southern blots of the genomic DNA extracted from the members of the recombinant inbred families T X CM, and Co X Tx, provided by B. Burr, B (Brookhaven National Laboratory), were probed with the sequence scMubG7-J, using the digoxigenin (DIG) DNA labelling and detection kit (Boehringer Mannheim), employing the modifications given by Maillet et. al. (this Newsletter). From the resulting luminographs the strain distribution pattern (SDP) was determined for this probe, which will be referred to as uwo1(scMubG7-J) on the RI linkage map. Comparison of the SDP for this sequence with the SDPs for all sequences contained within the RI database revealed very close linkage between our probe and two RFLP markers, npi438 and umc7, allowing uwo1(scMubG7-J) to be assigned a location on the long arm of chromosome 8 at position 92. 

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