Development of an SNP marker set for marker-assisted backcrossing using genotyping-by-sequencing in tetraploid perilla.

High-quality molecular markers are essential for marker-assisted selection to accelerate breeding progress. Compared with diploid species, recently diverged polyploid crop species tend to have highly similar homeologous subgenomes, which is expected to limit the development of broadly applicable locus-specific single-nucleotide polymorphism (SNP) assays. Furthermore, it is particularly challenging to make genome-wide marker sets for species that lack a reference genome. Here, we report the development of a genome-wide set of kompetitive allele specific PCR (KASP) markers for marker-assisted recurrent selection (MARS) in the tetraploid minor crop perilla. To find locus-specific SNP markers across the perilla genome, we used genotyping-by-sequencing (GBS) to construct linkage maps of two F2 populations. The two resulting high-resolution linkage maps comprised 2326 and 2454 SNP markers that spanned a total genetic distance of 2133 cM across 16 linkage groups and 2169 cM across 21 linkage groups, respectively. We then obtained a final genetic map consisting of 22 linkage groups with 1123 common markers from the two genetic maps. We selected 96 genome-wide markers for MARS and confirmed the accuracy of markers in the two F2 populations using a high-throughput Fluidigm system. We confirmed that 91.8% of the SNP genotyping results from the Fluidigm assay were the same as the results obtained through GBS. These results provide a foundation for marker-assisted backcrossing and the development of new varieties of perilla.

Transluminal removal of a fractured and embolized indwelling central venous catheter in the pulmonary artery.

Vascular catheters are associated with complications such as infection, thrombosis and stenosis. The embolization of a venous catheter fragment is a rare complication. A 39-year-old woman underwent placement of a totally implantable venous access device for chemotherapy to treat a recurrent liposarcoma of the left thigh. The "pinch-off sign" was noted on a routine chest X-ray but that was ignored. Three-months after implantation of the intravenous access device, the indwelling central catheter was fractured and embolized to the pulmonary trunk. The catheter in the pulmonary trunk was successfully removed through a percutaneous femoral vein approach using a pigtail catheter and goose neck snare.