Ionic effect on combing of single DNA molecules and observation of their force-induced melting by fluorescence microscopy

Molecular combing is a powerful and simple method for aligning DNA molecules onto a surface. Using this technique combined with fluorescence microscopy, we observed that the length of lambda-DNA molecules was extended to about 1.6 times their contour length (unextended length, 16.2 micrometers) by the combing method on hydrophobic polymethylmetacrylate (PMMA) coated surfaces. The effects of sodium and magnesium ions and pH of the DNA solution were investigated. Interestingly, we observed force-induced melting of single DNA molecules.Comment: 12 page

The peroxisome proliferator-activated receptor delta +294T > C polymorphism and alcohol consumption on serum lipid levels

<p>Abstract</p> <p>Background</p> <p>The single nucleotide polymorphism (SNP) of peroxisome proliferator-activated receptor delta (<it>PPARD</it>) gene affects serum lipid profiles, but to what extent alcohol consumption interferes with this association remains unknown. The present study was undertaken to compare the association of <it>PPARD </it>+294T > C (rs2016520) polymorphism and serum lipid levels in the nondrinkers and drinkers.</p> <p>Methods</p> <p>A total of 685 unrelated nondrinkers and 497 drinkers aged 15-82 were randomly selected from our previous stratified randomized cluster samples. Genotyping of the <it>PPARD </it>+294T > C was performed by polymerase chain reaction and restriction fragment length polymorphism. Interactions of the <it>PPARD </it>+294T > C genotypes and alcohol consumption on serum lipid levels were detected by using a factorial regression analysis after controlling for potential confounders.</p> <p>Results</p> <p>The levels of triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) A1, and the ratio of ApoA1 to ApoB were higher in drinkers than in nondrinkers (<it>P </it>< 0.05-0.001). There were no significant differences in the levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and ApoB between the two groups (<it>P </it>> 0.05 for all). The frequencies of TT, TC and CC genotypes were 56.0%, 36.4% and 7.6% in nondrinkers, and 57.2%, 38.0% and 4.8% in drinkers (<it>P </it>> 0.05); respectively. The frequencies of T and C alleles were 74.2% and 25.8% in nondrinkers, and 76.2% and 23.8% in drinkers (<it>P </it>> 0.05); respectively. There was also no significant difference in the genotypic and allelic frequencies between males and females in both groups (<it>P </it>> 0.05 for all). The levels of TC in nondrinkers were different among the three genotypes (<it>P </it>= 0.01), the C allele carriers had higher serum TC levels than the C allele noncarriers. The levels of all seven lipid traits in drinkers were not different among the three genotypes (P > 0.05 for all). The interactions of <it>PPARD </it>+294T > C genotypes and alcohol consumption on serum lipid levels were not detected in the drinkers (<it>P ></it>0.05 for all). Multiple linear regression analysis showed that serum TC, HDL-C, LDL-C, ApoA1, and ApoB levels were correlated with genotypes in drinkers but not in nondrinkers (<it>P </it>< 0.05-0.01).</p> <p>Conclusions</p> <p>These results suggest that the great majority of our study populations are beneficial from alcohol consumption. But there is no interaction between the <it>PPARD </it>+294T > C genotypes and alcohol consumption on serum lipid levels in the drinkers.</p