Vol 10, No 4 (2012)

The paper describes the early part of Barbara McClintock`s work on DNA transposons in maize, in which she discovered the Ac-Ds family of mobile "controlling elements". An account is first given of the cytology of the system that was used to generate intact chromosomes having "sticky" (broken) ends. Cytogenetical aspects of the chromatid and chromosome breakage-fusion-bridge cycles, deriving from breakage, are then described, which leads on to the way in which variegation in phenotypes of the maize kernels could be "read" in terms of chromosome breakage. The "genetic earthquake" event of 1944, triggered by introducing broken chromosomes into a zygote from both parents, lead to the discovery of Ds and Ac. Finding mobility of Ds from one chromosomal location to another was pure serendipity: the transposition showed itself while experiments were being undertaken to accurately map Ds. A similar chance observation revealed transposition of Ac as well, and then the relationship between the two elements was elucidated in terms of their autonomous and non-autonomous nature.

The review critically examines the current state of population epigenetics. Possible mechanisms of intergenerational inheritance of epigenetic and epigenomic modifications as a condition of population epigenetics reality are examined. Special attention is paid to the role of external factors, including diet and various chemical compounds as modulators of the epigenome, and the possible inheritance of epigenetic variability characteristics under the influence of such environmental factors. The role of epigenetic mechanisms in the etiology and susceptibility to complex human diseases is considered.

A population study of polymorphisms of EFEMP1, ZBTB38, HHIP, LCORL, ADAMTSL3, CDH13, JAZF1, IGF1R, GHSR, CABLES1, IFNG, VDR3, and IGFBP3 genes, which possibly influence human height, was carried out using PCR-RFLP. Population frequencies of alleles and genotypes for these genes were established. A correlation between the rs572169 variant of GSHR gene and male height was found . We suggest a model for prediction of human height on the basis of logistic regression method. The obtained data indicate a possibility to assess human height on the basis of genetic markers.

Using pea single mutant lines SGEFix–-2 (sym33) and RisFixV (sym42), which are characterized by different abnormalities during symbiotic nodule development, including thickening of infection threads’ walls, a double mutant RBT4 line, carrying a pair of symbiotic genes sym33 and sym42 was constructed. The epistasis of the mutant allele sym33 over the mutant allele sym42 with respect to the histological and ultrastructural organisation of nodules was shown. Thus, it was demonstrated that Sym33 gene functions earlier in symbiotic nodule development than Sym42 gene.