PubMed Health⌕ Search

Biomedical subjects

S Fields

Publications and source records attributed to S Fields.

At least 145 records · Page 8Linked to original sources
PubMed1985

The yeast STE12 product is required for expression of two sets of cell-type specific genes.

Yeast alpha and a cells transcribe distinct sets of genes involved in mating behavior, alpha-specific genes and a-specific genes, respectively. The alpha 1 product of the alpha mating type locus (MAT alpha) has been the only known activator of either set of genes; it is required for synthesis of RNA from the alpha-specific genes, one of which is the major alpha-factor gene. By screening for mutants that are no longer able to express this gene, we have identified the STE12 gene product as another positive regulator of the alpha-factor gene. alpha ste12 cells are also defective in RNA production from the other known alpha-specific genes. Moreover, a ste12 cells fail to produce wild-type levels of RNA from the a-specific genes. The STE12 gene product is therefore an activator of two sets of genes involved in yeast cell type specialization.

Genes↗
PubMed1982

Nucleotide sequence of human influenza A/PR/8/34 segment 2.

The nucleotide sequence of RNA segment 2 of human influenza strain A/PR/8/34 has been determined. Segment 2 in 2341 nucleotides long and encodes a protein of 757 amino acids (86,500 daltons molecular weight) which is involved in RNA synthesis. Although segment 2 is identical in size to segment 1, which encodes a protein of related function, neither the nucleotide sequences of these two RNA segments nor the amino acid sequences of the encoded proteins appear to be homologous. The sequence of segment 2 completes the sequence of the virus (total 13,588 nucleotides).

Amino Acid Sequence↗
PubMed1982

Nucleotide sequences of influenza virus segments 1 and 3 reveal mosaic structure of a small viral RNA segment.

Defective interfering RNAs of influenza virus are small segments derived from viral segments 1, 2 and 3. We present here the complete nucleotide sequences of segments 1 and 3 from the human influenza strain A/PR/8/34 and deduce that the sequence of a small RNA segment from A/NT/60/68, apparently a defective interfering RNA, is derived from five separate regions in segment 3 and from one region in segment 1. These regions, which are located near the terminal of the two parental segments, are arranged in the small RNA segment in an alternating fashion: thus a region derived from near 5' terminus is adjacent to a region derived from near a 3' terminus. We propose that the small segment is generated during positive strand synthesis as a result of the viral polymerase pausing at uridine-rich sequences in the template and reinitiating synthesis at another site.

Base Sequence↗
PubMed1982

Comparative morphometry of the nasal cavity in rats and mice.

The distribution of the various epithelial types lining the nasal cavity in normal 7 and 16 weeks old male Fischer-344 rats and male B6C3F1 mice has been mapped at the light microscopic level. Photographs of transverse sections of the nose were analysed using a Zeiss Videoplan computerized image analysis system programmed for measurement and evaluation of count, area, perimeter and length. In rats, the volumes of the nasal cavity at 7 and 16 weeks are 156 and 257 mm3 respectively; while in mice the nasal cavity volume is essentially the same (32 . 5 and 31 . 5 mm3) at the same two ages. Total surface areas of the nasal cavity in rats at 7 and 16 weeks are 799 and 1344 mm2 respectively; and in mice 278 and 289 mm2. The percentages of the nasal cavity surface lined by squamous, respiratory and olfactory epithelium are similar at both ages in both species. Applications and significance of these data are discussed.

Age Factors↗
PubMed1981

The structure of two subgenomic RNAs from human influenza virus A/PR/8/34.

The nucleotide sequences of two subgenomic RNA segments from influenza virus A/PR/8/34 have been determined by cloning viral cDNA into the vector M13mp7. Sequence analysis was facilitated by a re-cloning strategy which takes advantage of both wild-type and amber derivatives of the M13 vector. The RNA species (444 and 480 nucleotides) contain the 5' and 3' termini of segment 1 and therefore derive by simple internal deletions of this segment. However, these species are not exact copies of the terminal regions of the progenitor segment but contain a few base changes. These differences suggest that after these RNAs have arisen, their sequences can drift, presumably reflecting a lower selective pressure than on the standard RNA segments.

Base Sequence↗
PubMed1981

Structure of the neuraminidase gene in human influenza virus A/PR/8/34.

The complete structure of the neuraminidase gene in influenza A/PR/8/34 has been determined by cloning into the bacteriophage M13 and sequencing with dideoxynucleotide chain terminators. The gene is 1,413 nucleotides long, codes for a protein of 454 amino acids and has five potential glycosylation sites. We suggest that the neuraminidase, unlike the influenza haemagglutinin, is oriented with its N-terminus buried in the viral membrane.

Amino Acid Sequence↗
PubMed1981

The use of synthetic oligodeoxynucleotide primers in cloning and sequencing segment of 8 influenza virus (A/PR/8/34).

Complete double-stranded DNA copies of the RNA genes of the human influenza virus A/PR/8/34 have been synthesized by using two synthetic oligodeoxynucleotide primers. The gene encoding the non-structural proteins NS1 and NS2, prepared with these primers, has been cloned into the bacteriophage M13mp7 and sequenced. The sequence is compared with that from another human strain and from an avian strain.

Amino Acid Sequence↗
PubMed1981

Nucleotide-sequence heterogeneity and sequence rearrangements in influenza virus cDNA.

Double-stranded cDNA has been synthesized from influenza virus RNA and cloned into derivatives of the bacteriophage M13 for sequence analysis. The characterization of over 200 clones has permitted an analysis both of nucleotide sequence heterogeneity and of clones containing unusual rearrangements of sequence. Heterogeneity, due to genetic variability in the RNA population and to in vitro synthetic errors, was detected at the low level of one nucleotide difference per 3 700 nucleotides. By contrast, gross sequence rearrangements were identified in eight clones. Inversions of sequence within the same cDNA molecule were the predominant type of rearrangement, and three mechanisms for producing such inversions are discussed. In addition, we observed rarer clones containing sequence from one RNA molecule joined to that from another molecule.

Base Sequence↗
PubMed1980

Cloning of influenza cDNA ino M13: the sequence of the RNA segment encoding the A/PR/8/34 matrix protein.

A strategy has been developed for sequencing the single-stranded RNA genes of influenza virus. Restriction fragments derived from double-stranded cDNA copies of total influenza RNA were cloned into the bacteriophage M13mp2 and sequenced by the dideoxy technique. Sequences were extended and overlapped by using the virion RNA as template and priming with small restriction fragments. In the course of this strategy, the nucleotide sequence of segment 7 (1027 nucleotides) was completed and provides the primary structure of the matrix protein (27, 861 daltons). In addition, there is a second long reading frame which partly overlaps the reading frame of the matrix protein.

Base Sequence↗