Sex chromosome positions in human interphase nuclei as studied by in situ hybridization with chromosome specific DNA probes

Two cloned repetitive DNA probes, pXBR and CY1, which bind preferentially to specific regions of the human X and Y chromosome, respectively, were used to study the distribution of the sex chromosomes in human lymphocyte nuclei by in situ hybridization experiments. Our data indicate a large variability of the distances between the sex chromosomes in male and female interphase nuclei. However, the mean distance observed between the X and Y chromosome was significantly smaller than the mean distance observed between the two X-chromosomes. The distribution of distances determined experimentally is compared with three model distributions of distances, and the question of a non-random distribution of sex chromosomes is discussed. Mathematical details of these model distributions are provided in an Appendix to this paper. In the case of a human translocation chromosome (XqterXp22.2::Yq11Y qter) contained in the Chinese hamster x human hybrid cell line 445 x 393, the binding sites of pXBR and CY1 were found close to each other in most interphase nuclei. These data demonstrate the potential use of chromosome-specific repetitive DNA probes to study the problem of interphase chromosome topography

Detection of chromosome aberrations in the human interphase nucleus by visualization of specific target DNAs with radioactive and non-radioactive in situ hybridization techniques: diagnosis of trisomy 18 with probe L1.84

The localization of chromosome 18 in human interphase nuclei is demonstrated by use of radioactive and nonradioactive in situ hybridization techniques with a DNA clone designated L1.84. This clone represents a distinct subpopulation of the repetitive human alphoid DNA family, located in the centric region of chromosome 18. Under stringent hybridization conditions hybridization of L1.84 is restricted to chromosome 18 and reflects the number of these chromosomes present in the nuclei, namely, two in normal diploid human cells and three in nuclei from cells with trisomy 18. Under conditions of low stringency, cross-hybridization with other subpopulations of the alphoid DNA family occurs in the centromeric regions of the whole chromosome complement, and numerous hybridization sites are detected over interphase nuclei. Detection of chromosome-specific target DNAs by non-radioactive in situ hybridization with appropriate DNA probes cloned from individual chromosomal subregions presents a rapid means of identifying directly numerical or even structural chromosome aberrations in the interphase nucleus. Present limitations and future applications of interphase cytogenetics are discussed

P6348Phospholamban antisense oligonucleotides drive the reversal of cardiac dysfunction and multiple heart failure parameters during murine dilated cardiomyopathy

Abstract Background Mice lacking muscle LIM protein (Mlp/Cspr3 −/−) develop dilated cardiomyopathy (DCM). Previous work established this model to be amenable to improvements in cardiac function by genetic ablation of phospholamban (PLN). Purpose To test the hypothesis that therapeutic reductions of PLN would similarly improve cardiac function, Mlp KO mice were administered an antisense oligonucleotide (ASO) targeting PLN. Methods Echocardiography measurements of ejection fraction (EF), end-diastolic volume (EDV) and end-systolic volume (ESV) were performed before and after treatment. In addition, global transcriptome profiling using 3'RNA-seq was performed to identify gene expression changes in diseased Mlp KO mice and following PLN ASO treatments. Mlp KO mice with ejection fraction (EF%) of less than 45% (median, 37.6%; interquartile range, 32.2–42.0%) were treated with vehicle (n=10) or PLN ASO (n=9) for 4 weeks. Results Three subcutaneous injections of PLN ASO were administered to Mlp KO mice resulting in 50–70% PLN reductions. Echocardiography performed at study end revealed improvements of EF (60±8 vs. 46±12%), ESV (31±11 vs. 56±21μl) and EDV (79±22 vs. 100±25μl) with PLN ASO treatment. Corrected for baseline values, PLN ASO treatment improved all echocardiographic measurements (p&lt;0.001). Transcriptional analyses revealed that PLN ASO treatment reduced expression of heart failure related markers, such as Myh7 (−70%), Nppa (−72%), Nppb (−71%), Acta1 (−84%) and Ankrd1 (−40%), p&lt;0.05 vs. vehicle. In addition, genes not previously known to be dysregulated in this model, Edn3 and Xirp2, were identified and shown to be reduced following PLN ASO treatment by 71% and 67%, respectively (p&lt;0.001). Bioinformatic analysis suggested improvement of known and novel heart failure associated pathways by PLN inhibition in this model. In conclusion, antisense inhibition of PLN reduced functional and transcriptional indices of heart failure in a DCM model. In view of the failed CUPID trials, a gene therapy approach to improve SERCA2a activity, targeting PLN with ASO may be advantageous due to a likely more robust pharmacological profile. </jats:sec