The brittle rachis character, which causes spontaneous shattering of spikelets, has an adaptive value in wild grass species. The loci Br1 and Br2 in durum wheat (Triticum durum Desf.) and Br3 in hexaploid wheat (T. aestivum L.) determine disarticulation of rachides above the junction of the rachilla with the rachis such that a fragment of rachis is attached below each spikelet. Using microsatellite markers, the loci Br1, Br2 and Br3 were mapped on the homoeologous group 3 chromosomes. The Br2 locus was located on the short arm of chromosome 3A and linked with the centromeric marker, Xgwm32, at a distance of 13.3 cM. The Br3 locus was located on the short arm of chromosome 3B and linked with the centromeric marker, Xgwm72 (at a distance of 14.2 cM). The Br1 locus was located on the short arm of chromosome 3D. The distance of Br1 from the centromeric marker Xgdm72 was 25.3 cM. Mapping the Br1, Br2 and Br3 loci of the brittle rachis suggests the homoeologous origin of these 3 loci for brittle rachides. Since the genes for brittle rachis have been retained in the gene pool of durum wheat, the more closely linked markers with the brittle rachis locus are required to select against brittle rachis genotypes and then to avoid yield loss in improved cultivars.

We report a case of systolic and diastolic musical murmurs that developed 4 years after DDD pacemaker implantation. Echocardiographic examination disclosed no evidence of serious pacemaker-related complications. Pulsed Doppler examination with a sample volume at the right ventricular portion of a pacemaker lead showed prominent harmonic signals. The timing of the signals was consistent with that of musical murmurs. We considered vibration of the pacemaker lead as a possible origin of the musical murmurs. Systolic and diastolic musical murmurs can develop without serious cause in a patient with a transvenous pacemaker. Pulsed Doppler examination was useful in detecting the origin of musical murmurs.