Construction of a 5000 Rad and a 15000 Rad Radiation Hybrid Panels for the Dromedary Camel

Radiation Hybrid (RH) panel is a classic tool for generating high-resolution chromosome maps and anchoring genome sequence assemblies to chromosomes. The genome sequence of the dromedary (Camelus dromedarius) is currently assembled into scaffolds but not aligned with physical chromosomes.

Here we used the standard irradiation and cell fusion technique to generate radiation hybrid clones for the dromedary RH panels with two levels of resolution. Thymidine kinase (TK^-) deficient Chinese hamster cell line A23 was fused with primary fibroblast cell lines of two dromedaries: a female dromedary fibroblasts, irradiated at 5000 rad (50 Gy), and a male dromedary fibroblasts, irradiated at 15000 rad (150 Gy). In total, we obtained 249 clones for the 5000 rad and 238 clones for the 15000 rad irradiation doses.

We designed 44 PCR primers for markers evenly distributed across the genome (one or two markers per chromosome) and analyzed DNA of 186 clones from the 5000 rad and 93 clones from the 15000 rad panels. The estimated marker retention frequency was 54% for the 5000 rad and 43% for the 15000 rad.

Next, we will select clones with the lowest discordance rate to finalize the radiation hybrid panels for dromedary camel. The final RH panel will be characterized by sequencing to construct the whole genome RH map. The development of whole genome radiation hybrid panels for the dromedary is an important step towards high-resolution genome mapping and genome assembly at chromosome level for this species, and for the development of molecular tools for genome analysis in camelids.