Comparison of the genetic distances by three-point test with the actual positions of the cDNA regions on a chromosome of the silkworm, Bombyx mori
2007
Mase, K.(National Inst. of Agrobiological Sciences, Matsumoto, Nagano (Japan)) | Iizuka, T. | Okada, E. | Yamamoto, T. | Hara, W.
The morphological linkage map of Bombyx mori has been made by the combination of linkage analyses of BFsub(1), i.e., heterozygous females crossed with homozygous males, and the three-point analyses of reciprocal BFsub(1). We have advanced the methods of linkage analysis and three-point analysis by using EST-cDNA clones' RFLP as a marker. In the present study, we tried to perform fluorescence in situ hybridization (FISH) vs. chromosomal specimens from the ovaries of larvae on day 1 of the fifth instar in order to compare the genetic distances with the actual positions on a chromosome. The probes used were a mixture of digoxigenin-labeled medium-sized Bombyx genomic fragments corresponding to six cDNA clones located on three sites (4, 18 and 36 cM) of the RFLP linkage group 9 (RFLG9). As a result, three groups of specific spot signals with different intensities were concurrently detected on a pachytene bivalent. These three kinds of signals were relatively positioned at 24.9+-3.1, 45.2+-4.1 and 70.8+-3.8%. These values were roughly in agreement with the previously obtained genetic distances of the sites on RFLG9 from which the probes were taken.
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