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Biomedical subjects

S A Luk'ianov

Publications and source records attributed to S A Luk'ianov.

At least 19 recordsLinked to original sources
PubMed2004

[Cloning and analysis of a new neurogene in the mouse].

The previously described gene sip1 belongs to transcription factors of the zinc finger family. It has been ascertained recently that this gene is involved in TGF signaling cascade. Mutations in human gene sip1 cause Hirschprung syndrome. The expression of gene sip1 during embryonic mouse development was studied by in situ hybridization and immunostaining. Starting at E12.5, sip1 transcripts are present in a number of tissues: in the cortical plate, ventricular zone of the basal ganglion, thalamus, pons and midbrain, in specific nuclei of the brain stem and in the dorsal part of the spinal cord. In the developing cerebral cortex, sip1 expression is region-specific. In the brain of adult mice, sip1 expression is mostly detected in hippocampus, dentate gyrus, and white matter of the neocortex. Sip1 protein expression in the cerebral cortex is mostly confined to glutamatergic neurons.

Animals↗
PubMed1999

[Selective suppression of polymerase chain reaction].

The selective suppression of the polymerase chain reaction and methods based upon it (construction of cDNA libraries from low amounts of biological material, subtractive hybridization and differential display of mRNA, fast cloning of full-size cDNA, chromosome walking, cloning in vitro, and others) are reviewed. These methods display a high effectiveness and, taken together, enable intricate DNA analyses to be performed--from the search for nontrivial sequences to the total sequencing of the corresponding genes.

3' Untranslated Regions↗
PubMed1999

[Cloning and structure of gene encoded alpha-latrocrustoxin from the Black widow spider venom].

The primary structure of the crusta gene encoding alpha-latrocrustoxin (alpha-LCT), a high molecular mass neurotoxin specific to crustaceans, was determined in the black widow spider Latrodectus mactans tredicimguttatus genome. The total length of the sequenced DNA was 4693 bp. The structural part of the black widow spider chromosome gene encoding alpha-LCT does not contain introns. The sequenced DNA contains a single extended open reading frame (4185 bp) and encodes a protein precursor of alpha-LCT, comprising 1395 aa. We assume the Met residue at position -10 relative to the N-terminal residue of Glu1 of the mature toxin to be the first one in the protein precursor. The calculated molecular mass of the precursor (156147 Da) exceeds that of the mature toxin by approximately 30 kDa. These data are in agreement with the notion that over the course of maturation the protein precursor undergoes double processing--cleavage of a decapeptide from the N-terminal part and of a approximately 200-aa fragment from the C-terminal part. alpha-LCT displayed a number of imperfect ankyrin-like repeats and areas of structural homology with earlier studied latrotoxins; the highest homology degree (62%) was revealed with alpha-latroinsectotoxin (alpha-LIT).

Amino Acid Sequence↗
PubMed1998

[Cloning of region-specific genetic markers of planaria using a new method--ordered differential display].

A new method for finding differentially expressed genes, termed ordered differential display of mRNAs (ODD), was used in the search for region-specific molecular markers of freshwater planarian Dugesia tigrina. In this method, the effect of selective suppression of a polymerase chain reaction (PCR) is used for the differential amplification of a pool of 3'-terminal cDNA fragments generated by digestion of cDNAs with a restriction endonuclease. In the resulting amplified cDNAs, every mRNA is represented by a cDNA fragment whose length is determined by the position of the restriction site nearest to the 3'-terminus. Subsequent PCR with primers 3'-extended by two random nucleotides allowed the amplification of 1/192 part of all cDNA molecules present in the sample. The comparison of the generated pools of cDNA molecules separated by PAGE leads to the identification of differentially expressed sequences. The systematic study of the total mRNA pool is achieved by the successive use of all possible combinations of extended primers. Some sequences preferentially expressed along the anterior-posterior axis of planarian were identified using ODD.

Animals↗
PubMed1997

[In vitro cloning of DNA fragments by one polymerase chain reaction].

An improved version of the in vitro DNA cloning method described earlier is proposed. The method allows amplification by polymerase chain reaction (PCR) of individual DNA molecules of an unknown primary structure followed by sequencing. The modifications described here provide for in vitro cloning by means of a 40-45-cycle PCR (the original protocol required two consecutive amplifications). In addition, the in vitro cloning is suggested to be carried out in special 96-well plates in the presence of ethidium bromide; upon UV irradiation, the wells containing amplified DNA fluoresce to make the analysis of all 96 wells unnecessary. The improved protocol makes the preparation of individual in vitro clones more straightforward and less expensive.

Base Sequence↗
PubMed1996

[Cloning cDNA for the ha-SDGF gene from a Syrian hamster cell line with increased metastatic potential using subtractive hybridization].

Using subtractive hybridization, a cDNA library containing over 50% of clones specific for a highly metastatic cell line was obtained from two hamster embryo fibroblast lines with different metastatic potentials. Most of the clones (83%) contained new sequences. One clone contained the ha-SDGF gene cDNA homologous to SDGF cDNA from rodents. The level of ha-SDGF mRNA expression was considerably higher in the highly metastatic cell line.

Amino Acid Sequence↗
PubMed1996

[A method for obtaining the normalized cDNA libraries based on the effect of suppression of polymerase chain reaction].

A new efficient method for obtaining cDNA libraries with equal representation of all cDNA types (equalized libraries) in a single round of equalization was developed. The method is based on differences in the renaturation kinetics of double-stranded cDNAs of different genes and allow the selection of the equalized single-stranded fraction resulted from the incomplete reassociation of the total cDNA without laborious and inefficient physical separation. The equalized single-stranded fractions are selectively amplified by polymerase chain reaction (PCR). The amplification of other DNA molecules is inhibited due to PCR suppression, i.e. the suppression of amplification of the DNA molecules flanked with long interval terminal repeats in PCR with a primer corresponding to the external moiety of the repeat. The efficiency of the developed method was estimated in obtaining an equalized cDNA library based on mRNA from the activated human T lymphocyte Jurkat cell line.

Base Sequence↗
PubMed1996

[A novel method of subtraction cDNA hybridization allowing cloning of genes showing differential expression in cell micropopulations].

A novel, efficient and simple technique that combines subtractive hybridization with kinetic enrichment is proposed for obtaining enriched cDNA. The method is based on the use of a set of special primers that allow for the selective amplification by PCR only of differentially distributed sequences. Using the proposed technique, cDNA of a new gene XEp-1, specifically expressed in the presumptive epidermis of Xenopus laevis, was cloned, starting with the stage of midgastrula.

Amino Acid Sequence↗
PubMed1994

[Highly-effective subtractive hybridization of cDNA].

A scheme for subtractive hybridization is described allowing for a 500-1000 fold enrichment of low abundant cDNA. The scheme is based on the previously described principle of normalization of an initial mixture of differently represented cDNAs in the single-stranded portion of a tracer after the first round of subtraction and the principle of a trapper excluding the fraction of the double-stranded cDNAs formed during the first round from the subsequent PCR-amplification. The technique is simple and makes unnecessary the separation of the tracer, driver and hybrids formed after the subtraction.

Base Sequence↗
PubMedDate not supplied

[A method for the preparation of normalized cDNA libraries enriched with full-length sequences].

We developed a new method for the preparation of normalized cDNA libraries enriched with full-length sequences. It is based on the properties of the recently characterized duplex-specific nuclease from the hepatopancreas of the Kamchatka crab. The duplex-specific nuclease is thermostable, it effectively cleaves double-stranded DNA and is inactive toward single-stranded DNA (Shagin et al., Genome Res., 2002, vol. 12, pp. 1935-1942). Our method enables the normalization of cDNA samples enriched with full-length sequences without use of laborious and ineffective stages of physical separation. The efficiency of the method was demonstrated in model experiments using cDNA samples from several human tissues.

Animals↗
PubMedDate not supplied

[A family of genes of multidomain free lectins from a planarian: structure, expression, and use as markers for regeneration monitoring ].

A family of genes of the agamic race of planarian Girardia tigrina were described that encode proteins that belong to the superfamily of C-type lectins and were demonstrated to have a unique domain organization. The genes are differentially expressed in the planarian body. The protein products of at least two genes (scarf2 and gtlec1) are expressed in specifically differentiated gland cells of the planarian and secreted into the environment through long cell necks. A comparison of the results obtained by electron microscopy and immunohistochemistry with literature data allows the assignment of these cells to the group of adhesion glands. The observation of the regeneration of the cell necks in normal and artificial two-headed planaria indicated that the dorsoventral contact at the edge of the head part of the planarian body directs and maintains the growth of the gtLec1-producing cell necks during regeneration. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.

Amino Acid Sequence↗
PubMedDate not supplied

[A new planarian extrachromosomal virus-like element revealed by subtraction hybridization].

A combination of suppression subtraction hybridization (SSH) and a new technique of mirror orientation selection (MOS) was used to compare the total DNA for two, sexual (SR) and asexual (AR), races of freshwater planarian Giradia tigrina. Several race-specific DNA fragments were found. A new element termed planarian extrachromosomal virus-like element (PEVE) was revealed in AR. The PEVE genome contains two unique regions, Ul and Us, which are flanked by inverted repeats. Two variants observed for the PEVE genome differ in combination of single- and double-stranded regions corresponding to Ul and Us. The PEVE genome codes for two helicases, one homologous to the circovirus replication initiation protein (Rep) and one corresponding to the helicase domain of papillomavirus E1. PEVE is nonuniformly distributed though the planarian body and is possibly replicated only in certain parenchymal cells.

Amino Acid Sequence↗
PubMedDate not supplied

[A natural fluorescent protein that changes its fluorescence during maturation].

The gene of a new red fluorescent protein zoan2RFP from a coral polyp Zoanthus sp., a homologue of the known green fluorescent protein from the Aequorea victoria jellyfish, was cloned. At early maturation stages, zoan2RFP exhibits a green fluorescence, which then turns into the red one. A similar phenomenon was recently reported for the E5 mutant of the red fluorescent coral protein DsRed. Zoan2RFP differs from E5 by faster maturation kinetics and the complete disappearance of green fluorescence in the mature protein. Naturally occurring proteins of this type can be considered as intermediate forms between the green and red fluorescent proteins, which are formed during the microevolution of fluorescent proteins.

Amino Acid Sequence↗
PubMedDate not supplied

[Methodological approaches to detecting mRNA in histological sections].

This paper reviews methodological approaches to detection of mRNA on histological sections using in situ hybridization. Alongside with the review of literature we present a detailed description of our own modification of this technique, based on the use of paraffin sections of the material fixed by replacement in the frozen state. Particular attention is given to methodological problems facing the researcher who is using in situ hybridization for the first time.

Acridine Orange↗
PubMedDate not supplied

[The space-time distribution of the mRNA of the nuclear proteins c-myc and P-53 in the development of the clawed toad studied by hybridization in situ].

We studied distribution of mRNA for nuclear protooncogene c-myc and nuclear protein P-53 in mature oocytes and embryos of Xenopus laevis from the stage of fertilization up to the stage of hatching by in situ hybridization with histological sections. mRNA for c-myc was present in all cells of the embryo at all studied developmental stages. Between the stage of fertilization and up to the late blastula, mRNA concentration for c-myc decreased progressively in all embryonic cells. During gastrulation a local increase in the concentration of this messenger was found in dorsal mesoderm and ectoderm. At the stage of neurula increased concentration of mRNA for c-myc was observed in all cells of the embryo but the hybridization signal increased particularly distinctly in cells of the neural tube. In studies of P-53 mRNA distribution hybridization signal was detected only in brain cells after stage 20 of development (after closure of the neural folds) and up to the stage of hatching.

Animals↗
PubMedDate not supplied

[The spatial-temporal distribution of the mRNA of the Na+-K+-ATPase alpha-subunit in the early development of the clawed toad studied by hybridization in situ].

Distribution of Na+-K+-ATPase alpha-subunit mRNA in full-grown oocytes and early embryos from of X. laevis has been studied using in situ hybridization on histological sections. The mRNA is dispersed about equally in the cytoplasm and is absent from the nucleus. The concentration of the mRNA is successively decreased from fertilization to the late blastula. The drastic decrease in mRNA concentration is observed in a period from morula to mid-blastula. The local increase in the mRNA concentration was detected in dorsal mesoderm and ectoderm during gastrulation.

Animals↗
PubMedDate not supplied

[The spatio-temporal distribution of single-stranded breaks in nuclear DNA in sections of clawed toad embryos during gastrulation and neurulation].

Spatial and temporal pattern and quantities of nicks in nuclear DNA during gastrulation and neurulation was studied using nick-translation in sections of Xenopus laevis embryos. Specific changes in the number of nicks in different mesoderm and ectoderm regions were detected during embryogenesis. Dorso-ventral gradient of nuclear labelling was observed in mesoderm and inner ectoderm layer of early and middle gastrula. The gradient was inverted during transition from gastrula to neurula. At the same time dorso-ventral (in mesoderm) and ventro-dorsal (in outer ectoderm layer) gradients of nuclear labelling were increased. The intensity of nuclear labelling in all parts of embryo as a whole was remarkably higher during neurulation as compared with gastrulation. Dorso-ventral gradient of nuclear labelling was observed in mesoderm and ectoderm during neurulation. A connection between the nicks and differentiation status of the cells during early embryogenesis in amphibians is suggested.

Animals↗