| First Author | Taylor BA | Year | 1991 |
| Journal | Mouse Genome | Volume | 89 |
| Pages | 576-577 | Mgi Jnum | J:104880 |
| Mgi Id | MGI:3612974 | Citation | Taylor BA, et al. (1991) MEV/2Ty-at Ps Miwh CaJ, An improved MEV linkage testing stock. Mouse Genome 89:576-577 |
| abstractText | Full text of Mouse Genome contribution: MEV/2Ty-at Ps Miwh CaJ, AN IMPROVED MEV LINKAGE TESTING STOCK. B.A. Taylor, M. Ivey, and D. Grieco; The Jackson Laboratory, Bar Harbor ME 04609 U.S.A. INTRODUCTION In 1989 we reported the construction of a new linkage testing stock, MEVI/Ty, bearing 11 ecotropic murine leukemia virus proviruses located on ten different chromosomes (2). The presence or absence of these proviruses can be individually scored in Southern blots of HindIII digested, genomic DNA using the ecotropic MuLV-specific probe pEcB4. In addition three dominant visible markers had been introduced: hammer-toe (Hm), steel (Sl) and caracul-J (CaJ). However, because Hm and Sl are located on the same chromosomes as two of the proviral markers (Emv-24 and Emv-25, respectively), this choice of visible markers was sub-optimal. Furthermore, although all eleven proviruses could be discriminated in Southern blots of HindIII DNA, PvuII is the preferred restriction enzyme for analysis of ecotropic proviral analysis because it produces more dispersed 3' junction fragments. However, two of the proviruses (Emv-13 and Emv-25) could not be separated in PvuII digests. Here we describe a new version of the MEV stock that incorporates a new combination of dominant visible markers, and contains ten proviruses separable in either PvuII or HindIII digests. MATERIALS AND METHODS The source of the dominant visible markers white (Miwh, Chr 6) and black-and-tan (at, Chr 2) was the MWT/Le strain, while the source of polysyndactyly (Ps, Chr 4) was the C57BL/6J-Ps stock. Methods for DNA isolation, Southern analysis with the ecotropic-specific probe, and computing the distances swept have been described (2). The positions of individual markers and the genetic lengths of individual chromosomes are taken from the most recently published comprehensive map (1). RESULTS To be able to use PvuII as the restriction enzyme without sacrificing a marker, we have introduced the visible black-and-tan allele (at) of the agouti locus on Chr 2 and, simultaneously eliminated the closely linked Emv-13 provirus. Black-and-tan is an excellent marker because it is generally easy to classify, dominant to both nonagouti and wild-type, and appears not to affect viability and reproduction, even in homozygotes. The inclusion of the markers Ps and Miwh provides needed markers for Chr 4 and 6, respectively. Since both of these markers are near the middle of large linkage groups, they sweep maximal regions. Both of these markers are fully penetrant on different backgrounds. The Miwh mutation may interfere with classification of certain coat color mutations. However, Miwh is itself easier to classify than Sl on the MEV (a/a, d/d) background. The new strain breeds as well or better than the original MEV/1Ty-Hm Sl CaJ strain. It is anticipated that the stock is still segregating in some regions of the genome, but we have confirmed that the stock is homozygous for each of the Emv loci present in MEV/1Ty, with the exception of Emv-13, which has been deliberately eliminated. When the new stock is more inbred, we will characterize the stock with respect to common isozyme polymorphisms. All three of the new markers have been backcrossed to the MEV stock at least 10 generations, and three or more of the last backcrosses were to the inbred MEV/1Ty subline. It is our intent to maintain the new stock segregating for Ps, Miwh, and CaJ, but fixed for at. This stock has proviral or visible markers on 13 of the 19 autosomes and is estimated to sweep 66% of the autosomal genome in a backcross scored for 50 fully informative gametes. This is an improvement over the ~50% coverage provided by the original MEV/1Ty-Hm Sl CaJ stock. The new stock is designated MEV/2Ty-at Ps Miwh CaJ. The original stock will continue to be available, at least temporarily. Mice from the new stock can be obtained from The Jackson Laboratory. We are continuing to map novel proviruses which were discovered in the MEV stock and have been propagated to fixation. We hope to release in the near future a new MEV stock bearing additional proviruses that map to different chromosomes. Acknowledgments Mutant mouse stocks were obtained from the Mouse Mutant Resource. This work was supported by NIH grant CA33093. REFERENCES 1. Davisson MT, Roderick TH, Doolittle DP, Hillyard AL, Guidi JN: Locus map of the mouse (Mus musculus/domesticus). In "Genetic Maps: Locus Maps of Complex Genomes", Fifth Edition, (S. J. O'Brien, Ed.), Book 4, pp. 3-35, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY. (1990). 2. Taylor B.A., and L. Rowe. 1989. Genomics 5:221-232. |
