Presence Of Restriction Site Research Articles

Restriction endonuclease digestion of meiotic and mitotic chromosomes in Pyrgomorpha conica (Orthoptera: Pyrgomorphidae)

Mitotic and meiotic chromosomes of the grasshopper Pyrgomorpha conica were treated with the restriction endonucleases (REs) AluI, MboI, and HaeIII. Two important results were obtained. First, REs successfully acted to produce linear differentiation not only in mitotic but also in meiotic chromosomes. Second, the changes in pycnosis that occur in the chromatin from first prophase to first metaphase in meiosis, as revealed with orcein or Giemsa, do not affect the digestion capability of REs. This suggests that it is the presence of restriction sites, rather than chromatin condensation itself, that is critical in the production of the linear differentiation obtained.Key words: insect cytogenetics, restriction endonucleases, mitosis, meiosis, heterochromatin.

COMMON DNA POLYMORPHISM WITHIN CODING SEQUENCE OF APOLIPOPROTEIN B GENE ASSOCIATED WITH ALTERED LIPID LEVELS

60 of 83 middle-aged white men had an XbaI restriction site polymorphism within the coding sequence of the apolipoprotein B gene. Subjects homozygous and heterozygous for the presence of an XbaI restriction site had mean serum triglyceride levels 36% higher (p = 0.02) than those in homozygotes without the restriction site; there was a less substantial difference (p = 0.03) in serum cholesterol. The findings supported a dominant pattern of inheritance. The presence of this restriction site may increase the risk of atherosclerotic disease.