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Biomedical subjects

A A Bayev

Publications and source records attributed to A A Bayev.

At least 37 records · Page 2Linked to original sources
PubMed1983

Cloning and DNA sequence of the genes for two bacteriophage T5 tRNAsSer.

Bacteriophage T5 Bg/II/Hind III DNA fragment (803 basepairs), containing the genes for 2 tRNAs and 2 RNAs with unknown functions, was cloned in the plasmid pBR322. The analysis of DNA sequence indicates that tRNA genes code isoacceptor tRNAsSer (tRNA1Ser and tRNA2Ser) with anticodons UGA and GGA, respectively. The main unusual structural feature of these tRNAs is the presence of extra non-basepaired nucleotides in the joinings of stem 'b' with stems 'a' and 'c'.

Base Sequence↗
PubMed1982

Ubiquitous transposon-like repeats B1 and B2 of the mouse genome: B2 sequencing.

Mouse genome contains two major families of short interspersed repeats in more than 10(5) copies scattered throughout the whole genome. They are referred to as B1 and B2 sequences since they were first isolated from the genome library by means of a dsRNA-B probe /1/. In this work, two copies of the B2 family were sequenced and compared with the previously sequenced B1 repeat /2/. A B2 ubiquitous repeat is ca. 190 bp long. The members of the family deviate in 3-5% of nucleotides from the consensus sequence. B2 contains regions of homology to the RNA polymerase III split promoter and to 4.5S snRNA I. Both B1 and B2 contain regions which resemble junctions between exons and introns. In contrast to B1, B2 does not contain apparent homologies to papova viral replication origins and a human Alu sequence. One side of the B2 repeat is represented by a very AT-rich sequence (ca. 30 bp long) followed with an oligo (dA) stretch 10-15 nucleotides long. This region of the repeat is the most variable one. The whole unit is flanked with 15-16 bp direct repeats different in sequenced copies of B2. The same is true of some copies of the B1 family. The properties of B1 and B2 repeats suggest that they may represent a novel class of transposon-like elements in eukaryotic genome. A possible role of B-type repeats in genome reorganization, DNA replication and pre-mRNA processing is discussed.

Animals↗
PubMed1982

Cloning of genes for bacteriophage T5 stable RNAs.

One EcoRI-generated fragment (440 basepairs) and two EcoRI/HindIII fragments (220 and 960 basepairs) from the deletion region of T5 phage have been inserted into the phage lambda XIII and the plasmid pBR322 as vectors. Recombinant DNA molecules were studied by hybridization with in vivo 32P-labeled T5 4-5 S RNAs on nitrocellulose filters. Two-dimensional polyacrylamide gel electrophoretic fractionation and fingerprint analysis of the RNAs eluted from the filters were carried out to identify RNAs coded by cloned fragments. For the accurate localization of the genes for these RNAs, RNA-DNA hybrids were treated with T1 and pancreatic RNAases, and the eluted RNA fragments stable against RNAase action were electrophoresed. It was shown that the EcoRI 440 fragment contains the gene for tRNA 10 (tRNAAsp), the EcoRI/HindIII 220 fragment contains the gene for RNA III (107 bases) and parts of the genes for RNA I (107 bases) and tRNA 12 (tRNAHis), and the EcoRI/HindIII 960 fragment contains only a part of the gene for tRNA 9 (tRNAGln). The arrangement of these genes on the physical map of T5 phage was as follows: -tRNAGln-tRNAHis-RNA III-RNA I-...-tRNAAsp.

Bacteriophage lambda↗
PubMed1982

Cloning of bacteriophage T5 promoters.

Bacteriophage T5 was subjected to combined hydrolysis with the restriction endonucleases PstI and HindIII and the resulting fragments were inserted into the plasmid pBR322. Selection of transformants for Aps-Tcr-phenotype made it possible to screen the hybrid plasmids that contained promoter sequences in the cloned fragments. Two PstI/HindIII fragments, 720 bp (51% of the T5 DNA length) and 1,200 bp (70%) were cloned in this study. Tcr levels for these plasmids were as high as 18 micrograms/ml and 75 micrograms/ml, respectively. The presence of Escherichia coli RNA polymerase binding sites on both fragments was shown using the nitrocellulose filter assay. These binding sites are situated between 35 bp and 95 bp from the HindIII cleavage site on the 1,200 bp fragment; and within 420 bp from the HindIII site on the 720 bp fragment.

Base Sequence↗
PubMed1981

The structure of the yeast ribosomal RNA genes. 4. Complete sequence of the 25 S rRNA gene from Saccharomyces cerevisae.

The complete nucleotide sequence of the 25 S rRNA gene from one rDNA repeating unit of Saccharomyces cerevisiae has been determined. The corresponding 25 S rRNA molecule contains 3392 nucleotides and has an estimated relative molecular mass (Mr, Na-salt) or 1.17 x 10(6). Striking sequence homology is observed with known 5'- and 3'-end terminal segments of L-rRNA from other eukaryotes. Possible models of interaction with 5.8 S rRNA are discussed.

Animals↗
PubMed1981

Overproduction of the EcoRII endonuclease and methylase by Escherichia coli strains carrying recombinant plasmids constructed in vitro.

Recombinant DNA molecules were constructed from the plasmid pIL203 and the EcoRI-fragment of N3 plasmid containing EcoRII endonuclease and methylase genes and also a gene for resistance to sulfanilamide. The pIL203 plasmid, used as a vector, consisted of the Bam HI-EcoRI-fragment of the plasmid pBR322 conferring resistance to ampicillin and the Bam HI-EcoRI-fragment of lambda phage containing promoters, a thermosensitive mutation in the cI gene and a suppressible amber mutation in the cro gene. Ampicillin-sulfanilamide-resistant clones were selected and tested for their restriction and modification phenotype. The recombinant plasmid DNA, isolated from ApRSuR-resistant clones, which restricted and modified phage lambda imm21 with EcoRII specificity, had the EcoRI-fragment with EcoRII genes in a single orientation. The recombinant plasmid pSK323 was transferred into E. coli strains with su-, su1, su2 or su3 phenotypes. The synthesis of products of EcoRII genes by these strains grown at 37 degrees C is increased by 10--50-fold.

Cloning, Molecular↗
PubMed1981

On the origin of the H1N1 (A/USSR/90/77) influenza virus.

The influenza virus H1N1 (the A/USSR/90/77 strain) that reappeared in 1977 after the H1N1 influenza viruses had disappeared from the human population, is compared with the A/FM/1/47 and the A/FW/1/50 influenza viruses by the method of oligonucleotide mapping of individual segments of the viral RNAs. Seven genes of the A/USSR/90/77 virus appear to be very similar to the corresponding genes of the A/FW/1/50 virus, whereas the gene coding for the M protein displays considerable homology to the corresponding gene of the A/FM/1/47 virus. The data demonstrate that the A/USSR/90/77 strain is a recombinant virus.

Genes, Viral↗
PubMed1980

The structure of the yeast ribosomal RNA genes. I. The complete nucleotide sequence of the 18S ribosomal RNA gene from Saccharomyces cerevisiae.

The cloned 18 S ribosomal RNA gene from Saccharomyces cerevisiae have been sequenced, using the Maxam-Gilbert procedure. From this data the complete sequence of 1789 nucleotides of the 18 S RNA was deduced. Extensive homology with many eucaryotic as well as E. coli ribosomal small subunit rRNA (S-rRNA) has been observed in the 3'-end region of the rRNA molecule. Comparison of the yeast 18 S rRNA sequences with partial sequence data, available for rRNAs of the other eucaryotes provides strong evidence that a substantial portion of the 18 S RNA sequence has been conserved in evolution.

Animals↗
PubMed1980

Mobile dispersed genetic element MDG1 of Drosophila melanogaster: structural organization.

The whole-length mobile dispersed genetic element mdg1 has been cloned from D. melanogaster genome. It contains DNA fragments described earlier as Dm225 and Dm234, Mdg1 is 7.2 kb long and framed with two direct repeats of 300-400 base pairs each. Mdg1 family is represented by about 25 copies in the genome of flies and by 200 copies in the genome of cultured cell line 67J25D. Virtually all the copies in the genome of D. melanogaster have the same restriction map. Oligo(dA)-oligo(dT) regions were found within mdg1.

Animals↗
PubMed1980

The transposable element Mdg3 in Drosophila melanogaster is flanked with the perfect direct and mismatched inverted repeats.

MDg3 is a family of mobile dispersed genetic elements represented by 15 copies in the haploid genome of D. melanogaster and flanked, like other similar elements, by the regions of homology. In the present work, these regions of mdg3 have been sequenced. The existence of perfect direct repeats 268 base pairs long has been demonstrated. Inverted repeats are located on the gene distal side of them. It is possible to construct a perfect 8 b.p. palindrome or a slightly mismatched 18 b.p. palindrome. The inverted repeats are flanked by two short 5 b.p. direct repeats.

Animals↗
PubMed1980

The nucleotide sequence of the ubiquitous repetitive DNA sequence B1 complementary to the most abundant class of mouse fold-back RNA.

Three copies of a highly repetitive DNA sequence B1 which is complementary to the most abundant class of mouse fold-back RNA have been cloned in pBR322 plasmid and sequenced by the method of Maxam and Gilbert. All the three have a length of about 130 base pairs and are very similar in their base sequence. The deviation from the average sequence is equal to 4% and the overall mismatch between each two is not higher than 8%. One of the recombinant clones used contained two copies of B1 oriented in the same direction. All of the B1 copies are flanked with sequences which possess nonidentical but very similar structure. They consist of a number of AmCn blocks (where m varies from 2 to 8 and n equals 1-2). These peculiar sequences in all cases are separated from B1 by non-homologous DNA stretches of 2-8 residues. In one case, a long polypurine stretch is located next to such a block. It consists of 74 residues most of which represent a reiteration of the basic sequence AAAAG. We have found two regions within the B1 sequence which are homologous to the intron-exon junctions, especially to those present in the large intron of the mouse beta-globin gene. It may indicate the involvement of the B1 sequence in pre-mRNA splicing.

Animals↗
PubMed1980

Molecular cloning of EcoRII endonuclease and methylase genes.

The genes for restriction-modification system EcoRII have been cloned from plasmid N3 DNA using RSF2124 as a vector plasmid. The hybrid plasmids designated pFK321 and pFK322 contained a 5.8 megadaltons EcoRI--fragment derived from N3 DNA including the genes for restriction-modification system EcoRII and a gene for resistance to sulfanilamide.

Bacteriophage lambda↗