Genetic diversity within and between British and Irish breeds: the maternal and paternal history of native ponies.

The UK and Ireland have many native pony breeds with historical and cultural importance as well as being a source of uncharacterized genetic diversity. However, there is a lack of comprehensive research investigating their genetic diversity and phylogenetic interrelationships. Many studies contain a limited number of pony breeds or small sample sizes for these breeds. This may result in erroneous grouping of pony breeds that otherwise have intricate interrelationships with each other and are not evaluated correctly when placed as a token subset of a larger dataset. This is the first study that specifically investigates the genetic diversity within and between British and Irish native pony breeds using large sample numbers from locations of their native origin. This study used a panel of microsatellite markers and sequence analysis of the mitochondrial control region to analyze the genetic diversity within and between 11 pony breeds from Britain and Ireland. A large dataset was collected (a total of 485 animals were used for mtDNA analysis and 450 for microsatellite analysis), and previously published data were used to place the British and Irish ponies in a global context. The native ponies of Britain and Ireland were found to have had a complex history, and the interrelationships between the breeds were revealed. Overall, high levels of genetic diversity were maintained in native breeds, although some reduction was evident in small or isolated populations (Shetland, Carneddau, and Section C). Unusual mitochondrial diversity distribution patterns were apparent for the Carneddau and Dartmoor, although among breeds and global haplogroups there was a high degree of haplotype sharing evident, well-represented within British and Irish ponies. Ancestral maternal diversity was maintained by most populations, particularly the Fells and Welsh ponies, which exhibited rare and ancient lineages. The maternal and paternal histories of the breeds are distinct, with male-biased crossings between native breeds, and other shared influences, likely Arabs and Thoroughbreds, are apparent. The data generated herein provide valuable information to guide and implement the conservation of increasingly rare native genetic resources

Transfection efficiency and toxicity of polyethylenimine in differentiated Calu-3 and nondifferentiated COS-1 cell cultures

In the present study, we evaluated polyethylenimine (PEI) of different molecular weights (MWs) as a DNA complexing agent for its efficiency in transfecting nondifferentiated COS-1 (green monkey fibroblasts) and well-differentiated human submucosal airway epithelial cells (Calu-3). Studying the effect of particle size, zeta potential, presence of serum proteins or chloroquine, it appeared that transfection efficiency depends on the experimental conditions and not on the MW of the PEI used. Comparing transfection efficiencies in both cell lines, we found that PEI was 3 orders of magnitude more effective in COS-1 than in Calu-3 cells, because Calu-3 cells are differentiated and secrete mucins, which impose an additional barrier to gene delivery. Transfection efficiency was strongly correlated to PEI cytotoxicity. Also, some evidence for PEI-induced apoptosis in both cell lines was found. In conclusion, our results indicate that PEI is a useful vector for nonviral transfection in undifferentiated cell lines. However, results from studies in differentiated bronchial epithelial cells suggest that PEI has yet to be optimized for successful gene therapy of cystic fibrosis (CF)