Molecular cytogenetic organization of polytene chromosomes

The results of the works carried out in the Laboratory of Molecular Cytogenetics (Institute of Cytology and Genetics of Siberian Branch of the RAS, Novosibirsk) devoted to the molecular genetic analysis of main units of polytene chromosomes, bands, interbands, and puffs, as well as intercalary and pericentric heterochromatin, are summarized. The results are discussed in terms of the dynamic model of organization of polytene chromosomes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1622–1638, September, 1995.     

RNA targeting at any chosen site of interest by the novel RNA-protein hybrid ribozyme and the gene discovery based on the hybrid ribozyme libraries

RNA targeting by the RNA-protein hybrid ribozymes, whose protein part can specifically bind to the RNA helicase, is described.     

Markov chain Monte Carlo estimation of autoregressive models with application to metal pollutant concentration in sludge

This paper provides an introduction to and an overview of Bayesian estimation, based on Markov chain Monte Carlo techniques. Autoregressive time series models are considered in some detail. Finally, an example involving the modelling of a metal pollutant concentration in sludge is presented.     

Dealing with missing values and outliers in principal component analysis

An efficient methodology for dealing with missing values and outlying observations simultaneously in principal component analysis (PCA) is proposed. The concept described in the paper consists of using a robust technique to obtain robust principal components combined with the expectation maximization approach to process data with missing elements. It is shown that the proposed strategy works well for highly contaminated data containing different amounts of missing elements. The authors come to this conclusion on the basis of the results obtained from a simulation study and from analysis of a real environmental data set.     

Linkers for oligonucleotide microarray synthesis

A number of linkers for microchip-based (microarray) synthesis of oligonucleotides were synthesized here using photolabile intermediates. The resulting linkers are designed for covalent immobilization on slides containing both hydroxyl and amino groups.The first series of linkers was intended for the synthesis of oligonucleotide arrays for hybridization analysis. These linkers provide a strong covalent bond with the slide surface when amino groups in oligonucleotide heterocyclic bases are deprotected.The second series of linkers allows to cleave the synthesized oligonucleotides from the support on which they were synthesized. Furthermore, the use of such linkers yields oligonucleotides devoid of the phosphate group at their 3′ end.The obtained linkers were successfully tested in the synthesis of oligonucleotides on a microchip for subsequent hybridization analysis and assembly of a DNA fragment.     

Silencing lung cancer genes using miRNAs identified by 7mer-seed matching

Lung cancer (LC) is the main cause of cancer-associated deaths in both men and women globally with a very high mortality rate. The microRNAs (miRNAs) are a class of noncoding RNAs consisting of 18–25 nucleotides. They inhibit translation of protein through binding to complementary target mRNAs. The non-coding miRNAs are recognized as potent biomarkers for detection, development and treatment of malignancy. In this study, we screened a set of 12 genes over expressed in small cell lung cancer, non small cell lung cancer and the genes involved in both categories and their binding sites for human miRNAs as no work was reported yet. Screening of human miRNAs revealed that a few genes showed numerous miRNA binding sites. Free energy values of mRNA sequences revealed that they might acquire compact folded structure causing complexity for miRNAs to interact. GC content in the target site was relatively higher than that of their flanks. It was observed through analysis of cosine similarity metric and compAI parameters that the genes related to lung cancer were encoded with non optimal codons and thus might be translationally less efficient for producing polypeptides. Gene ontology analysis was carried out to understand the diverse functions of these 12 genes.     

Evolution of Complexity. Molecular Aspects of Preassembly

An extension of neo-Darwinism, termed preassembly, states that genetic material required for many complex traits, such as echolocation, was present long before emergence of the traits. Assembly of genes and gene segments had occurred over protracted time-periods within large libraries of non-coding genes. Epigenetic factors ultimately promoted transfers from noncoding to coding genes, leading to abrupt formation of the trait via de novo genes. This preassembly model explains many observations that to this present day still puzzle biologists: formation of super-complexity in the absence of multiple fossil precursors, as with bat echolocation and flowering plants; major genetic and physical alterations occurring in just a few thousand years, as with housecat evolution; lack of precursors preceding lush periods of species expansion, as in the Cambrian explosion; and evolution of costly traits that exceed their need during evolutionary times, as with human intelligence. What follows in this paper is a mechanism that is not meant to supplant neo-Darwinism; instead, preassembly aims to supplement current ideas when complexity issues leave them struggling.     

玉米×二倍体多年生类玉米后代的GISH分析

通过对玉米自交系旅9与二倍体多年生类玉米(Zea diploperennis,DP)远缘杂交,其杂种与玉米回交,回交一代(BC1)孤雌生殖,获得了具有DP性状的两个稳定株系a2-①和a2-⑥．对其中的外源渗入片段进行了荧光原位杂交物理定位,确定了a2-①中外源渗入片段在第1染色体长臂近束端,第2,8染色体长臂中部,以及第6染色体短臂中部．a2-⑥中外源渗入片段在第1染色体长臂近末端,第2,8染色体长臂中部．对两株系中渗入片段在染色体上的物理位置的特点,位置与抗病性之间的关系,以及可能携带有抗病基因的外源渗入片段等进行了初步的分析和讨论．     

胰岛素通过CREB调节肝脏糖异生的模型化研究

本文基于Hill动力学与Michaelis-Menten方程,建立理论模型研究胰岛素通过环磷腺苷效应元件结合蛋白(CREB)调节肝糖异生的物理机制.理论模型考虑胰岛素通过CREB调节过氧化物酶体增活化受体γ辅助活化因子(PGC)联级信号,进而调控肝脏糖异生,影响糖代谢信号通路特性.研究发现,在异常胰岛素(Ginsulin)作用下CREB表达提升,进一步刺激了磷酸烯醇式丙酮酸羧激酶1(Pck1)表达.通过Pck1的调控,柠檬酸盐酯(citrate)、α-酮戊二酸(α-keto glutarate)、苹果酸酯(Malate)、草酰乙酸盐(Oxaloacetate)出现了不同的代谢水平.高表达的CREB会上调Pck1的表达水平,通过CREB、Pck1的调节作用,磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate)转化为白藜芦醇(Pyruvate)的水平提升,进而促使citrate、α-keto glutarate、Malate、Oxaloacetate大幅度升高,最终影响细胞葡萄糖代谢.在糖异生基因的调控作用下,较高浓度的葡萄糖(Glocose),使得phosphoenolpyr...     

衣藻性别决定及交配过程中的基因调控

阐述了单细胞绿藻衣藻（Chlamydomonas）性别相关基因及其作用机制的研究进展,其中着重介绍了位于mt基因座及少量位于常染色体上的性别相关基因,并分析了它们在营养细胞分化为正负两种交配型的配子细胞、正/负配子的交配以及合子分化的起始这3个关键步骤中的调控作用.