We have used genomic denaturing gradient gel electrophoresis (gDGGE) and PCR across a variable length triplet repeat element to map the mouse Nrl gene close to the T-cell receptor alpha/nucleoside phosphorylase/ribonuclease-1 cluster on mouse Chromosome (Chr) 14, consistent with its position on human 14ql 1 (Yang-Feng and Swaroop 1992). This result was obtained with the BXD and AKXD recombinant inbred (RI) strains (Taylor 1990) and confirmed in a Mus. spretus backcross.
We recently cloned a human cDNA for a retinaspecific protein with a basic motif and sequences homologous to leucine zippers and called it neural retina leucine zipper (NRL, D14S46E) (Swaroop et al. 1992).
Isolation and sequence of the mouse cDNA and gene structure of the mouse homolog, Nrt, are described elsewhere (Farjo et al. 1993). In order to map Nrl to a mouse chromosome, we used three methods to detect polymorphisms: RFLPs, variation in triplet repeat length, and gDGGE. Using ten different restriction enzymes, we could not find any RFLP between strains AKR/J, C57L/J, C57BL/6J, and DBAJ2J. We therefore used gDGGE (Burmeister et al. 1991), a novel approach that may be useful in finding polymorphisms.
We also identified a short tandem repeat in the Nrl sequence and found it to be polymorphic.
The sequence of the mouse Nrl cDNA, derived from the BALB/c strain, contains a microsatellite repeat (AGG)19 in its 3' untranslated sequence (Farjo et al. 1993