Order of the aro-6 and cpl-1 loci on linkage group
VI of Neurospora.
Thomas J. Schmidhauser-Department of Biology, The University of Louisiana at Lafayette, Lafayette, LA.
The results reported here locate the cpl-1 locus 5.5 centimorgans to the left of the aro-6 locus on linkage group VIL of Neurospora.
The aro-6 (Halsall and Doy 1969 Biochim. Biophys. Acta 185:432-446), and cpl-1 (Chalmers 1973 Genetics 74s:43), loci have been mapped to the left arm of linkage group VI of Neurospora between the ad-8 and lys-5 loci. The order of aro-6 and cpl-1 on LGVIL has not been determined.
The cpl-1 lesion increases the sensitivity of Neurospora to chloramphenicol and is scored on medium supplemented with 1 mg/ml chloramphenicol. The wild type is resistant to 4 mg/ml chloramphenicol. The aro-6 locus encodesone of three Neurospora 3-deoxy-D-arabinoheptulosonic acid-7-phosphate synthase isozymes in the aromatic amino acid biosynthetic pathway. The aro-6 lesion prevents growth on minimal medium supplemented with inhibitors, tryptophan and phenylalanine, of the alternate two isozymes of the synthase.
The double mutant ad-8 1-152-7(E6), cpl-1 ANTAS6(s) A was isolated from a preliminary cross and crossed to aro-6 a DH1 (FGSC 1713) on solid synthetic crossing medium using aro-6 a as the female parent. Random ascospores were isolated onto 1 ml slants of Vogel's minimal medium supplemented with adenine in 75 mm tubes. Scoring was by transfer to slants of minimal medium with appropriate supplements. No double recombinants were observed.
|Data obtained from random ascospore isolates from aro-6 a x ad-8, cpl-1 A|
|Zygote genotype|| Parental
|Recombination|| Total and
ad-8 cpl-1 +
+ + aro-6
12 recombinants in region 1 out of 163 progeny yields an interval of 7.4 centimorgans.
9 recombinants in region 2 out of 163 progeny yields an interval of 5.5 centimorgans. The data is consistent with the order shown in Figure 1; of the three loci tested aro-6 is proximal to the LGVI centromere and the ad-8 locus is distal.
Figure 1. Relevant region of linkage group VI of Neurospora showing the locations of the aro-6 and cpl-1 loci.
Anya Alleman, Felica Eichler and Marcus Louis contributed to this work.
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