Study of mutation in tomato genomic DNA using low energy ion implantation or soybean DNA by RAPD

364-368To analyze mutation in tomato genomic DNA by RAPD technology, certain factors influencing RAPD amplification, such as, DNA template, Taq DNA polymerase, Mg2+, dNTPs and primer, were studied to optimize RAPD amplification reaction system. RAPD amplification of tomato genomic DNA after low energy ion implantation along with soybean DNA was successfully performed. Compared to the control, genomic DNA of tomato implanted with N+ or Ar+ ion beam displayed mutation. Further, total number of amplification band, number of differential band and rate of differential band increased when implantation dose of ion beam increased. The rate of differential band caused by Ar+ ion beam was higher compared to that by N+ ion beam under the same implantation dose. In addition, soybean DNA also had effect on tomato genomic DNA. In comparison to whole genomic DNA of soybean, the number and rate of differential band increased for random fractured genomic DNA of soybean, indicating that it might be easier for DNA fragment to enter into cell and integrate into genomic DNA of tomato as compared to the whole genomic DNA. Collectively, the rate of differential band was positively correlated with the implantation dose of ion beam, and the effect of soybean DNA fragment on tomato genomic DNA was higher compared to whole genomic DNA of soybean, which would provide basis for application of ion beam technology in tomato breeding. </span

Emergence and transmission pathways of rapidly evolving evolutionary branch C4a strains of human enterovirus 71 in the Central Plain of China.

BACKGROUND: Large-scale outbreaks of hand, foot, and mouth disease (HFMD) occurred repeatedly in the Central Plain of China (Shandong, Anhui, and Henan provinces) from 2007 until now. These epidemics have increased in size and severity each year and are a major public health concern in mainland China. PRINCIPAL FINDINGS: Phylogenetic analysis was performed and a Bayesian Markov chain Monte Carlo tree was constructed based on the complete VP1 sequences of HEV71 isolates. These analyses showed that the HFMD epidemic in the Central Plain of China was caused by at least 5 chains of HEV71 transmission and that the virus continued to circulate and evolve over the winter seasons between outbreaks. Between 1998 and 2010, there were 2 stages of HEV71 circulation in mainland China, with a shift from evolutionary branch C4b to C4a in 2003-2004. The evolution rate of C4a HEV71 was 4.99×10(-3) substitutions per site per year, faster than the mean of all HEV71 genotypes. The most recent common ancestor estimates for the Chinese clusters dated to October 1994 and November 1993 for the C4a and C4b evolutionary branches, respectively. Compared with all C4a HEV71 strains, a nucleotide substitution in all C4b HEV71 genome (A to C reversion at nt2503 in the VP1 coding region, which caused amino acid substitution of VP1-10: Gln to His) had reverted. CONCLUSIONS: The data suggest that C4a HEV71 strains introduced into the Central Plain of China are responsible for the recent outbreaks. The relationships among HEV71 isolates determined from the combined sequence and epidemiological data reveal the underlying seasonal dynamics of HEV71 circulation. At least 5 HEV71 lineages circulated in the Central Plain of China from 2007 to 2009, and the Shandong and Anhui lineages were found to have passed through a genetic bottleneck during the low-transmission winter season