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Biomedical subjects

O D Ermolaeva

Publications and source records attributed to O D Ermolaeva.

8 recordsLinked to original sources

Equalizing cDNA subtraction based on selective suppression of polymerase chain reaction: cloning of Jurkat cell transcripts induced by phytohemaglutinin and phorbol 12-myristate 13-acetate.

The major drawback of subtractive cDNA libraries is that the original disproportion in concentrations of different types of transcripts is preserved. This usually makes the isolation of specific rare transcripts extremely difficult. To overcome this difficulty, we propose a strategy that introduces the equalization of concentrations (normalization) of specific transcripts during the subtractive process. This makes possible obtaining both rare and highly abundant transcripts in the resulting subtracted library. This technique has been applied for isolation of transcripts activated upon induction of Jurkat cells by phytohemaglutinin and phorbol 12-myristate 13-acetate. Six novel up-regulated sequences belonging to a low-abundance class of transcripts have been obtained.

Blotting, Northern↗

Subtractive hybridization, a technique for extraction of DNA sequences distinguishing two closely related genomes: critical analysis.

The present status of genomic DNA subtraction techniques is reviewed. The advantages and disadvantages of the widely-used methods of genome subtraction are discussed. Using the kinetic model of subtractive hybridization developed by us previously (Sverdlov and Ermolaeva, 1993; Sverdlov and Ermolaeva, 1994), the application of genome subtraction to various problems is analyzed. It is concluded that the technique should be further advanced based on subtraction of single-stranded DNAs. This strategy would enable one to efficiently extract target sequences omitting the stage of genome simplification.

Animals↗

The mathematical model of subtractive hybridization and its practical application.

A novel theory of subtractive hybridization including (or based on) the kinetic model of this process was proposed. A computer program modeling the process of subtraction was developed. Basing on the theory, a novel method of subtractive hybridization was proposed allowing routine comparison of genomes and products of genome expression. The method was applied to studies of the genetic mechanisms of embryogenesis, regeneration, cell differentiation and tumor transformation.

Cell Differentiation↗

Physical mapping of sequences homologous to an endogenous retrovirus LTR on human chromosome 19.

The human genome contains multiple copies of sequences related to the HERV-K family of endogenous retroviruses, homologous to the B-type mouse mammary tumour virus. A DNA fragment closely resembling an HERV-K long tandem repeat (LTR) was detected in a library of hncDNA clones enriched for sequences from human chromosome 19. Sites showing homology to the sequence of this fragment have been identified on human chromosome 19 by hybridization to previously mapped chromosome 19 cosmids. Thus the distribution of LTR sequences on a specific human chromosome has been mapped for the first time. We estimate the total number of such sites on human chromosome 19 to be at least 110. Many of these sites are located in the vicinity of known genes. The precise localizations (to specific cosmids) of LTR-homologous sequences on chromosome 19 can serve as a reference source and will automatically provide further insight into LTR-gene relationships as new genes are mapped onto the chromosome.

Animals↗

SUBTRACT: a computer program for modeling the process of subtractive hydridization.

We report on a new software tool, SUBTRACT, which allows the analysis of the possible strategies for an experiment based on a mathematical model of subtractive hybridization. The program helps the experimenter choose the optimal strategy and conditions for performing the reaction. The program allows the modeling of cDNA and genomic subtraction for different types of target DNA. SUBTRACT offers a friendly interface for the investigation of the dynamics of the process of subtractive hybridization, and for modifying different parameters and initial conditions. SUBTRACT allows the user to plot the values of interesting quantities as a function of the reaction time. The program runs under the Unix operating system on Sun-compatible computers.

Algorithms↗

[Kinetic analysis for subtractive hybridization of transcripts].

A theoretical analysis of kinetics of two subtractive cDNA hybridizations has been carried out: hybridisation of an excess of denatured double-stranded cDNA (driver) with denatured double-stranded cDNA (tracer) containing some sequences (targets) missing from the driver, and hybridisation of denatured double-stranded tracer with denatured double-stranded driver unable to be renatured. Our calculations show that the first strategy requires several rounds of hybridisation for sufficient enrichment of tracer with target sequences of the low-abundant mRNA: in the first round the renatured fraction is removed, and in subsequent rounds the remaining single-stranded fraction cDNA is used and renatured fraction is collected. The second strategy makes it possible to sufficiently enrich non-reassociated fraction of tracer with minor fractions of target sequences in a single round of subtractive hybridisation.

DNA, Complementary↗

[Subtractive hybridization. Theoretical analysis, and a principle of the trap].

An analysis of the kinetics of the subtractive hybridization and the extent of enrichment of sequence differences between two otherwise identical genomes or transcripts has been carried out for different conditions. The hybridization of single- or double-stranded DNA (tracer) containing the difference (target) to the large excess of single-stranded complementary DNA not having the sequence (driver) gives a much higher enrichment of the target than hybridization of double-stranded driver and tracer or double-stranded driver with single-stranded tracer. The conclusion is that the first approach can give means for efficient extraction of the target without artificial simplifications of the genomes before subtraction. A principle of the "trapper", preventing the hybrids formed from dissociation in the course of PCR amplification of the target enriched, is proposed as a complement to the single-stranded DNA hybridization in the process of highly efficient subtraction.

DNA↗