PubMed Health⌕ Search

Biomedical subjects

M C Nguyen-Huu

Publications and source records attributed to M C Nguyen-Huu.

30 records · Page 2Linked to original sources
PubMed1983

Expression and regulation of a human metallothionein gene carried on an autonomously replicating shuttle vector.

A human metallothionein (MT) gene was inserted into a bovine papillomavirus (BPV) vector. The chimeric vector (pMTII-BPV) transforms rodent fibroblasts to a cadmium-resistant phenotype. The resistance is due to the high level of expression of human MT-II in those cells. The vector is maintained in the cells as a free replicating plasmid, present at about 10--15 copies per cell. Transcription of the episomal human MT-IIA gene is initiated from its authentic start sites and is regulated by the level of cadmium in the growth medium. The presence of the human MT-IIA gene allows the BPV replicon to function even though it is ligated to an intact copy of pBR322. Due to the presence of plasmid origins of replication and dominantly acting selective markers functional in both Escherichia coli and mammalian cells, pMTII-BPV can be used as a shuttle vector.

Animals↗
PubMed1979

Isolation and characterization of the chicken ovomucoid gene.

The chicken ovomucoid gene has been isolated by screening a chicken DNA library with a plasmid containing ovomucoid mRNA sequences. Twelve recombinant phages carrying ovomucoid mRNA sequences were isolated. Two of them, extending farthest into the 5' and 3' direction respectively, were characterized by restriction mapping and Southern hybridization as well as by electron microscopic analysis of hybrids between the cloned DNA and ovomucoid mRNA. Seven intervening sequences interrupt the ovomucoid mRNA sequence in chromosomal DNA. From these data a minimal size of 5.6 kb can be estimated for the length of the ovomucoid gene.

Animals↗
PubMed1979

Chicken lysozyme gene contains several intervening sequences.

The organization of the chicken lysozyme gene and its neighboring sequences was examined by a comparison of the restriction map of the lysozyme structural gene with the map of the lysozyme gene in genomic DNA. Chicken DNA was cleaved with restriction endonucleases and the DNA fragments were separated by agarose gel electrophoresis. After transfer of the fragments onto nitrocellulose filters, those fragments that contain lysozyme mRNA sequences were detected by hybridization of the filters to labeled probes generated from pls-1, a recombinant plasmid carrying the lysozyme structural gene. This analysis revealed the presence of at least three intervening sequences, two of which interrupt the protein coding region and one of which is located in the 3' untranslated region. When oviduct DNA and sperm DNA were compared, no difference was observed in the size and number of restriction fragments that contain either lysozyme or ovalbumin structural gene sequences.

Animals↗
PubMed1979

Arrangement of coding and intervening sequences of chicken lysozyme gene.

Hybrid phages that contain chicken lysozyme gene sequences have been isolated from a chicken DNA library. Two overlapping clones covering a region of 22 kilobase pairs around this gene have been studied by restriction mapping. Southern hybridization, and electron microscopic analysis of hybrids between lysozyme mRNA and the cloned cellular DNA. Three intervening sequences interrupt the lysozyme structural gene. The cellular gene is at least 3.9 kilobases long, about 6 times the length of the structural gene.

Animals↗
PubMed1978

Preferential transcription of the ovalbumin gene in isolated hen oviduct nuclei by RNA polymerase B.

The synthesis of ovalbumin mRNA sequences was studied in isolated nuclei from hen oviduct. Two different methods of analysis were used to distinguish in vitro synthesized from preexisting mRNA sequences: (i) Mercurated ribonucleotides were used for in vitro RNA synthesis, and the newly synthesized RNA was purified by chromatography on sulfhydryl-agarose and hybridized to radioactive ovalbumin cDNA. (ii) [3H]UTP was used to label the in vitro synthesized RNA. Hybridization to unlabeled mercurated cDNA, RNase A digestion, and subsequent purification of the hybrids on SH-agarose allowed the quantitation of newly synthesized ovalbumin mRNA sequences. Approximately 0.1% of the newly synthesized RNA was identified as ovalbumin RNA by both methods. The synthesis of ovalbumin RNA progressed during the incubation of nuclei and was sensitive to actinomycin D and low concentrations of alpha-amanitin. The preferential in vitro transcription of the ovalbumin gene (1000-fold over random transcription of the chicken genome) by RNA polymerase B (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) suggests that the specificity of in vitro RNA synthesis is retained in isolated nuclei.

Amanitins↗
PubMed1978

Cloning of chicken lysozyme structural gene sequences synthesized in vitro.

Double-stranded chicken lysozyme cDNA was synthesized from an oviduct mRNA fraction enriched for lysozyme mRNA. The ds-cDNA was inserted into the BamHI site of plasmid pBR322 using chemically synthesized DNA linker molecules containing the BamHI restriction endonuclease cleavage site. After bacterial transformation, colonies carrying lysozyme DNA were identified by hybridization with highly purified lysozyme cDNA. The 555 base pairs long cloned DNA fragment of one recombinant plasmid was isolated and characterized by restriction endonuclease digestion. The DNA sequence of selected parts of the inserted DNA is as predicted from the amino acid sequence of prelysozyme. The sequence data allows the unambiguous location of the coding region within lysozyme mRNA.

Animals↗
PubMed1978

Transcription of the chicken ovalbumin and conalbumin gene during early secondary induction with estrogens.

Estrogens stimulate the rate of transcription of the ovalbumin and conalbumin gene in the chicken oviduct. The synthesis of ovalbumin and conalbumin mRNA was studied in isolated nuclei. RNA synthesized in vitro was distinguished from preexisting nuclear RNA by affinity labeling the in vitro products with a mercurated nucleotide and subsequent purification of the Hg-RNA on SH-agarose. The content of ovalbumin and conalbumin mRNA sequences in the in vitro transcripts was determined by hybridization to cDNA. After the withdrawal of implanted hormones from chickens, the synthesis of conalbumin and ovalbumin RNA increased 2.5- and at least 20-fold, respectively, by treatment with estrogens. The maximal rate of transcription of the conalbumin gene is achieved within 2 h after estrogen induction, whereas the rate of transcription of the ovalbumin gene becomes maximal after a lag of several hours. These results demonstrate that estrogens affect two genes in the same target cell differently.

Amanitins↗
PubMed1977

A RNA-dependent RNA polymerase activity: implications for chromatin transcription experiments.

Mercurated nucleoside triphosphates have been used for transcription of chicken oviduct chromatin with E. coli RNA polymerase. The newly synthesized RNA was purified from preexisting RNA by SH-agarose chromatography and analyzed for the content of specific mRNA sequences. The apparent preferential production of ovalbumin mRNA sequences was not inhibited by actinomycin D, although total RNA synthesis was reduced by more than 90%. Furthermore, when globin mRNA alone, or added to oviduct chromatin, was incubated in the transcription assay, a significant fraction of this mRNA was retained on SH-agarose. The copurification of chromatin associated RNA with in vitro synthesized mercurated RNA was mainly due to a RNA-dependent synthesis of complementary sequences by the bacterial enzyme. Although denaturation of the transcripts prior to SH-agarose chromatography leads to a reduced contamination with endogenous ovalbumin specific RNA, we are unable to show that the messenger-specific RNA sequences purified with the newly mercurated RNA results from a DNA-dependent reaction.

Animals↗