PubMed Health⌕ Search

Biomedical subjects

V M Kavsan

Publications and source records attributed to V M Kavsan.

At least 19 recordsLinked to original sources
PubMed1991

5'-derivatives of oligonucleotides as primers of DNA polymerization catalyzed by AMV reverse transcriptase and Klenow fragment of DNA polymerase 1.

The Km and Vmax values for d(pT)8 and its derivatives containing various 5'-end groups were estimated in the reaction of polymerization catalyzed with AMV-RT and FK. The change in affinity of modified primers was more pronounced in the case of AMV-RT than in the case of FK. Introducing in d(pT)8 of intercalators such as phenazinium, ethidium and daunomycin residues results in 2.7-, 8.7- and 11-fold increases in the primer affinity to AMV-RT, respectively. However, in the case of hemin and cholesterol derivatives the Km values were 3 and 5 times higher than those for d(pT)8. Compared to d(pT)8, the affinity of FK to all the above analogs was 2.3-3.6 times higher with the exception of cholesterol derivative to which it was 2.4-fold lower. The effect of the 5'-end residues on the Vmax values of d(pT)8 was small and ranged from 44% to 120% of that for d(pT)8. Therefore such reactive derivatives of oligonucleotides can be used as effective primers of AMV-RT and FK. Possible reasons for various effects of the 5'-end residues of the primer on its interaction with FK or AMV-RT in the presence of poly(A) are discussed.

Avian Myeloblastosis Virus↗
PubMed1991

Variability of polyadenylation sites in mRNAs from human fetal liver.

cDNA libraries of human fetal liver were constructed in pBR322 and lambda gt10 vectors. The libraries were screened for liver-specific clones by differential hybridization. This procedure revealed 25 and 32 liver-specific clones in plasmid and phage libraries, respectively. The majority of these clones were represented with serum albumin, fetal G gamma-globin and A gamma-globin cDNA inserts. Three types of 3'-non-coding region were found in 5 sequenced albumin cDNAs. In one type mRNA the distance between the AATAAA signal and polyadenylation site was 15 nucleotides, in 2 other types this distance was 10 and 6 nucleotides. The polyadenylation site in the G gamma-globin cDNA was located 2 nucleotides further from AATAAA signal, while in the A gamma-globin cDNA it was 2 nucleotides closer to the signal as compared with the results published previously.

Base Sequence↗
PubMed1990

A comparison of the initiating abilities of ribo- and deoxyriboprimers in DNA polymerization catalyzed by AMV reverse transcriptase.

The difference in optimal conditions for DNA polymerization catalyzed by AMV reverse transcriptase on poly(A) and poly(dA) templates with d(pT)10 and (pU)10 primers has been found. A comparison of the initiating abilities of d(pT)10 and (pU)10 primers under optimal conditions for various template.primer complexes has been made. The best template.primer complex was poly(A).d(pT)10 and the worst was poly(A).(pU)10. The lengthening of d(pT)n primers by a mononucleotide unit (n = 2-10) increases their affinity by a factor of about 2 and 3 in the case of poly(dA) and poly(A) templates, respectively. The affinities of d(pT) to the enzyme does not change with the primer length.

Avian Myeloblastosis Virus↗
PubMed1990

[Molecular basis of retrovirus adaptation: nucleotide sequence of Rous sarcoma virus adapted to duck cells].

The host range of retroviruses is rather complex and specific. It is controlled by the products of viral structural genes that interact with the determinants both on the surface and within the cell. The possibility to infect and transform duck embryo fibroblasts is shown for the Prague strain of chicken Rous sarcoma virus (subgroup C), though virus production in these cells is restricted. However, after the 6th passage the "adapted" virus gave the titre practically the same as it was for chicken embryo fibroblasts. Provirus of RSV adapted to the duck embryo fibroblasts and integrated into host DNA was isolated from the library of nucleotide sequences of duck embryo fibroblasts transformed by this virus. The nucleotide sequence of such provirus was determined. The alterations in gp85 coding region of the env gene which proved to be the result of recombination with endogeneous RAV-0 sequences were shown. The formation of viral particles with rather high titre was induced by the proviral transfection on both chicken and duck embryo fibroblasts. The contribution of the revealed alterations in the genome of transformation active virus and possible participation of its td mutant in the adaptation to the new host are discussed.

Adaptation, Physiological↗
PubMed1990

[Heterogeneity of polyadenylation site of mRNA coding for human serum albumin].

Human fetal liver cDNA was cloned in pBR322 vector by dG:dC-tailing method. The cDNA library was screened for liver-specific clones by means of differential hybridization. Human fetal liver and human kidney cDNAs were used as hybridization probes. Application of this procedure revealed twenty five liver-specific clones among about one thousand recombinants analysed. These clones represent cDNAs corresponding abundant mRNAs. Eighteen clones were identified as encoding serum albumin. Two different mRNA polyadenylation sites were found in four sequenced plasmids. Cleavage/polyadenylation site in two plasmids, pHA1 and pHA12, is situated fifteen nucleotides downstream the AATAAA signal; in two other plasmids, pHA8 and pHA25, this site is ten nucleotides downstream the same signal.

Amino Acid Sequence↗
PubMed1986

3'-Hydroxymethyl 2'-deoxynucleoside 5'-triphosphates are inhibitors highly specific for reverse transcriptase.

dNTP(3'-OCH3), a 3'-O-methyl derivative of dNTP, is a chain terminator substrate for DNA synthesis catalyzed by AMV reverse transcriptase. The enzyme seems to be the only DNA polymerase susceptible to the inhibitor while all the other DNA polymerases tested are fully resistant to the nucleotide analog. The resistant polymerases are: E. coli DNA polymerase I, Klenow's fragment of DNA polymerase I, phage T4 DNA polymerase, calf thymus DNA polymerase alpha, rat liver DNA polymerase beta and calf thymus terminal deoxyribonucleotidyl transferase.

Animals↗
PubMed1985

[Hybridization of low molecular weight nuclear RNA with pre-mRNA from erythroid bone marrow cells and rabbit mRNA].

Hybridization of labeled low molecular weight (LMW) nuclear RNA's to pre-mRNA from rabbit non-matured erythroid bone marrow cells or globin mRNA from reticulocytes revealed three RNA species having approximately 90, 100 and 160 nucleotides which are were specifically hybridized with purified cytoplasmic globin messenger RNA, while one (100 nucleotides) was also hybridized with rabbit 18S rRNA. The identity of these rabbit RNAs to LMW RNAs described for other animal species, as well as their possible hybridization sites and function are discussed.

Animals↗
PubMed1979

A study of barley stripe mosaic virus (BSMV) genome. I. Determination of sequence homology between BSMV RNA species.

The sequence homology between individual RNA species of three-component Norwich strain of BSMV (BSMV-N) has been studied by kinetic hybridization analysis using complementary DNAs obtained for each of the three BSMV-N RNA species by the method of Taylor et al. (1976). No significant sequence homology could be detected between RNA 1, on the one hand, and RNA2 and RNA3, on the other, whereas RNA2 and RNA3 were found to be highly homologous.

Base Sequence↗