DNA MUTAGENESIS IN PANAX GINSENG CELL CULTURES

At the present time, it is well documented that plant tissue culture induces a number of mutations and chromosome rearrangements termed “somaclonal variations”. However, little is known about the nature and the molecular mechanisms of the tissue culture-induced mutagenesis and the effects of long-term subculturing on the rate and specific features of the mutagenesis. The aim of the present study was to investigate and compare DNA mutagenesis in different genes of Panax ginseng callus cultures of different age. It has previously been shown that the nucleotide sequences of the Agrobacterium rhizogenes rolC locus and the selective marker nptII developed mutations during long-term cultivation of transgenic cell cultures of P. ginseng. In the present work, we analyzed nucleotide sequences of selected plant gene families in a 2-year-old and 20-year-old P. ginseng 1c cell culture and in leaves of cultivated P. ginseng plants. We analysed sequence variability between the Actin genes, which are a family of house-keeping genes; the phenylalanine ammonia-lyase (PAL) and dammarenediol synthase (DDS) genes, which actively participate in the biosynthesis of ginsenosides; and the somatic embryogenesis receptor kinase (SERK) genes, which control plant development. The frequency of point mutations in the Actin, PAL, DDS, and SERK genes in the 2-year-old callus culture was markedly higher than that in cultivated plants but lower than that in the 20-year-old callus culture of P. ginseng. Most of the mutations in the 2- and 20-year-old P. ginseng calli were A↔G and T↔C transitions. The number of nonsynonymous mutations was higher in the 2- and 20-year-old callus cultures than the number of nonsynonymous mutations in the cultivated plants of P. ginseng. Interestingly, the total number of N→G or N→C substitutions in the analyzed genes was 1.6 times higher than the total number of N→A or N→T substitutions. Using methylation-sensitive DNA fragmentation assay, we showed that the level of methylcytosine was higher in the DNA of the 20-year-old P. ginseng calli that than that in the DNA of the 2-year-old calli. Taken together, the data obtained demonstrate that both 2- and 20-year-old subculturing of P. ginseng tissues in vitro increased the number of point mutations, the diversity of mutation types, and the number of potential DNA methylation sites in the analyzed gene regions. It is possible that these mutation processes is the main reason underlying the decline in the vigor and regenerability of P. ginseng tissue culture over time

High statistic measurement of the K- -> pi0 e- nu decay form-factors

The decay K- -> pi0 e- nu is studied using in-flight decays detected with the ISTRA+ spectrometer. About 920K events are collected for the analysis. The lambda+ slope parameter of the decay form-factor f+(t) in the linear approximation (average slope) is measured: lambda+(lin)= 0.02774 +- 0.00047(stat) +- 0.00032(syst). The quadratic contribution to the form-factor was estimated to be lambda'+ = 0.00084 +- 0.00027(stat) +- 0.00031(syst). The linear slope, which has a meaning of df+(t)/dt|_{t=0} for this fit, is lambda+ = 0.02324 +- 0.00152(stat) +- 0.00032(syst). The limits on possible tensor and scalar couplings are derived: f_{T}/f_{+}(0)=-0.012 +- 0.021(stat) +- 0.011$(syst), f_{S}/f_{+}(0)=-0.0037^{+0.0066}_{-0.0056}(stat) +- 0.0041(syst).Comment: 11 pages, 8 figures. Accepted by Phys.Lett.

Effective Functional Form of Regge Trajectories

We present theoretical arguments and strong phenomenological evidence that hadronic Regge trajectories are essentially nonlinear and can be well approximated, for phenomenological purposes, by a specific square-root form.Comment: 29 pages, LaTeX. Published versio

Rectangular dielectric structures for the wakefield acceleration experiments in KIPT

At the Kharkov Institute of Physics and Technology is planned experimental test of the basic principles of the multi-bunch multi-mode dielectric wakefield accelerator. For this purpose we carried out a series of calculations of wakefield excitation and dynamics of the drive and witness bunches in rectangular structures with a dielectric sub-strate. For optimization two rectangular vacuum waveguides of R32 (72.14 × 34.04 mm) and R26 (86.36 × 43.18 mm) which were filled with the dielectric covering two any opposite metal walls of a waveguide were chosen. As possible dielectric Alumina, Cordierite, or Teflon were tested. It was supposed that the structure will be energized by train of electron bunches (bunch repetition frequency is 2.805 GHz) of 4.5 MeV energy, average current is 1 A. As the candidate for operating mode the LSM-wave or the LSE-wave, with frequency to equal the bunch repetition frequency or its doubled frequency were tested. The gradient of an accelerating field, small transverse deflection (or divergence) of drive and witness bunches were the main criteria of optimization. As a result of optimization we propose some dielectric structures for future wakefield experiments in KIPT.У ХФТІ запланована експериментальна перевірка основних принципів багатозгусткового й багатомодового кільватерного прискорювача. Для цього виконана серія розрахунків збудження кільватерних полів і динаміки провідного згустка та згустка, що прискорюється в прямокутних вакуумних хвилеводах R32 (72,14 × 34,04 мм) та R26 (86,36 × 43,18 мм), які заповнювалися діелектриком, що нанесен на дві протилежні металеві стінки хвилеводу. У якості матеріалу діелектрика тестувалися Alumina, Cordierite та Teflon. Прискорювальна структура збуджувалася послідовністю електронних згустків з частотою проходження 2,805 ГГц з енергією 4,5 МеВ і середнім струмом 1 A. У якості робочих мод тестувалися LSM- та LSE-хвилі із частотою, що дорівнює частоті проходження згустків або подвоєній до неї частоті. Основними критеріями оптимізації були градієнт прискорювального поля, мала величина поперечного відхилення провідного згустка та згустка, що прискорюється. У результаті оптимізації нами було запропоновано кілька діелектричних структур для майбутніх кільватерних експериментів.В ХФТИ запланирована экспериментальная проверка основных принципов многосгусткового и многомодового кильватерного ускорителя. Для этого проведена серия расчетов возбуждения кильватерных полей и динамики ведущего и ускоряемого сгустков в прямоугольных вакуумных волноводах R32 (72,14 × 34,04 мм) и R26 (86,36 × 43,18 мм), которые заполнялись диэлектриком, нанесенным на две противоположные металлические стенки волновода. В качестве материала диэлектрика тестировались Alumina, Cordierite и Teflon. Ускорительная структура возбуждалась последовательностью электронных сгустков с частотой следования 2,805 ГГц, энергией 4,5 МэВ и средним током 1 A. В качестве рабочих мод тестировались LSM- и LSE-волны с частотой, равной частоте следования сгустков или ее удвоенной частоте. Основными критериями оптимизации были градиент ускоряющего поля, малая величина поперечного отклонения ведущего и ускоряемого сгустков. В результате оптимизации нами было предложено несколько диэлектрических структур для будущих кильватерных экспериментов

Type D retrovirus specific sequences in lymphocytes of the children with Burkitt-type lymphoma and their parents

Type D retroviruses cause immunodeficiency in monkey. Earlier we have revealed genetical and serological markers of type D retroviruses in children with Burkitt-type lymphoma. Using PCR/Southern blotting assay we have found sequences related to MPMV in PBMC's DNA from children with Burkitt-type lymphoma and from their parents. Moreover, the data on sequencing of virus specific sequences from one ill child and from his mother have been presented. © 2001 Elsevier Science B.V. All rights reserved

Type D retrovirus specific sequences in lymphocytes of the children with Burkitt-type lymphoma and their parents

Type D retroviruses cause immunodeficiency in monkey. Earlier we have revealed genetical and serological markers of type D retroviruses in children with Burkitt-type lymphoma. Using PCR/Southern blotting assay we have found sequences related to MPMV in PBMC's DNA from children with Burkitt-type lymphoma and from their parents. Moreover, the data on sequencing of virus specific sequences from one ill child and from his mother have been presented. © 2001 Elsevier Science B.V. All rights reserved

Secondary metabolites: a boon from plants, the best chemist in nature: preface from the editors

[No abstract available