Genomic changes at the early stage of somatic hybridization.

A broad spectrum of genetic and epigenetic changes is induced by wide hybridization and subsequent polyploidization, but the timing of these events remains obscure because early hybrid cells are very difficult to harvest and analyze. Here, we used both cytological and genetic marker approaches to analyze the constitution of very young somatic hybrid cells between japonica rice (Oryza sativa L. subsp japonica) and indica rice (Oryza sativa L. subsp indica) and between japonica rice and bread wheat (Triticum aestivum L.). Chromatin elimination, simple sequence repeats, and retrotransposon profile deletions were already apparent within six days of the fusion event. The evidence we have presented suggests that genomic changes induced by genomic shock occur soon after the formation of hybrid cells.

Polymorphisms of the ATP1A1 gene associated with mastitis in dairy cattle.

Mastitis affects the concentrations of potassium and sodium in milk. Since sodium-potassium adenosine triphosphatase (Na(+), K(+)-ATPase) is critical for maintaining the homeostasis of these two ions, and is involved in cell apoptosis and pathogenesis, we presumed that polymorphism of the ATP1A1 gene, which encodes the bovine Na(+), K(+)-ATPase α1 subunit could be associated with mastitis. The ATP1A1 gene was analyzed in 320 Holstein cows using PCR low ionic strength single-strand conformation polymorphism (PCR-LIS-SSCP) and DNA sequencing methods. A C/A SNP was identified at nucleotide position -15,739 in exon 17 of the ATP1A1 gene, but it did not induce any change in amino acids. We examined a possible association of polymorphism of the ATP1A1 gene with somatic cell score and 305-day milk yields. Individuals with genotype CC in ATP1A1 had significantly lower somatic cell scores and 305-day milk yields than those with genotype CA. We also examined changes in Na(+), K(+)-ATPase activity of red cell membranes. The Na(+), K(+)-ATPase activity was significantly higher in dairy cows with genotype CC compared to the other two genotypes, and the Na(+), K(+)-ATPase activity of the resistant group was significantly higher than that of the susceptible group in dairy cows. We conclude that this polymorphism has potential as a marker for mastitis resistance in dairy cattle.