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Biomedical subjects

F Gannon

Publications and source records attributed to F Gannon.

At least 127 records · Page 7Linked to original sources
PubMed1980

The ovalbumin gene family: structure of the X gene and evolution of duplicated split genes.

The X, Y and ovalbumin genes, which are found within a 40 kb region of the chicken genome, are all expressed in oviduct under steroid hormone control, and share some sequence homologies. We have now cloned the complete X gene and have analyzed its structure. It codes for two RNA species, X and X'; both are coded by eight exons and appear to differ only by the size of their 3' untranslated region, X' RNA being 1400 nucleotides longer than X RNA. The striking similarity in the number and length of the exons which constitute the X, Y or ovalbumin genes establishes that they have evolved from a common ancestor gene by duplication events. Comparison of selected regions of the X and ovalbumin genes indicates that the exon sequences coding for protein and the location of the splice junctions have been well-conserved. The introns and the 3' untranslated exonic sequences have diverged much more rapidly. Four regions of apparently unrelated repetitive sequences are found both outside the X gene and within it (in two introns and in the sequence coding for the 3' untranslated part of X'RNA). The intragenic repetitive sequences have no counterpart in the ovalbumin and Y genes.

Animals↗
PubMed1980

Restriction mapping of cDNA recombinants including the adult chicken and duck globin messenger sequences: a comparative study.

A comparison of the organization of six avian adult globin messenger sequences is based on previously reported recombinant duck adult globin cDNA plasmids (Therwath et al., 1980) and the actual construction and characterization of pBR322 recombinant plasmids including the beta and the normal alpha A and alpha D chicken adult globin mRNA sequences. Identification of the cloned DNA was performed using hybridization-selection under conditions permitting complete purification in one step of the three globin mRNAs, and translation of the corresponding mRNA. Orientation of the globin insert in the vector was determined, taking into account the computer prediction of the restriction sites based on the known amino acid sequences of the three globin chains (Roizès and Pelaquier, 1980) and those actually observed, and by identification of restriction fragments using 3'-specific probes. Identification, orientation and restriction mapping of these cloned DNAs reveals extensive homologies in organisation of beta sequences between duck and chicken, as well as among the alpha sequences in every two possible combinations.

Animals↗
PubMed1980

Isolation and characterization of the mouse metallothionein-I gene.

Double-stranded cDNA was synthesized from a mouse liver mRNA fraction enriched for metallothionein mRNA activity, ligated to restriction site linkers, inserted into pBR322, and used to transform Escherichia coli chi 1776. The sequence of the largest plasmid containing DNA that hybridized to metallothionein mRNA was determined and shown to contain a 380-base-pair insert that includes the entire coding region and 3' untranslated region of metallothionein-I. The metallothionein-I insert was nick-translated and used to screen both a mouse myeloma and a mouse embryo DNA library in bacteriophage lambda. A metallothionein-I genomic clone containing 13-15 kilobase pairs of mouse DNA was isolated from each library. Both contain a 3.8-kilobase-pair EcoRI fragment that hybridizes to the metallothionein-I probe. The location, size, and orientation of the metallothionein-I gene within the 3.8-kilobase-pair fragment were determined by heteroduplex and restriction mapping. The gene spans 1.1 kilobase pairs and contains at least two introns.

Animals↗
PubMed1980

Molecular cloning of bovine thyroglobulin complementary DNA. Characterization of 2500-base-pair and 1900-base-pair fragments.

Double-stranded thyroglobulin complementary DNA (cDNA) was synthesized from purified 33-S bovine thyroglobulin mRNA. This synthetic structural gene has previously been shown to contain three sites for the restriction endonuclease HindIII, yielding two internal fragments of 1900 and 2500 base pairs respectively. Recombinant molecules were prepared by ligating the HindIII-restricted cDNA to the plasmid pBR322 which had been linearized by the same enzyme. When Escherichia coli was transformed with this mixture, it yielded two kinds of colonies each harboring recombinant plasmids containing one of the two cDNA fragments. Both recombinant molecules hybridized specifically to translatable thyroglobulin mRNA. Sequence homology between the two cloned DNAs could not be detected by cross-hybridization experiments; this argues against the existence of internal structural repetition in thyroglobulin subunits. Together, the two cloned DNA fragments represent 55% of the 8000-base-pair double-stranded thyroglobulin DNA.

Animals↗
PubMed1979

Organization and sequence studies of the 17-piece chicken conalbumin gene.

The conalbumin gene has been cloned and shown to consist of at least 17 exons approximately 60-200 base pairs long. The DNA sequence upstream from the region coding for the 5' end of the mRNA shows similarities with sequences present in homologous positions in other genes. High and low frequency repetitive sequences are found both upstream from the conalbumin gene and within one intron.

Animals↗
PubMed1979

Cloning of an almost full-length chicken conalbumin double-stranded cDNA.

Chicken conalbumin double-stranded cDNA (con-dscDNA) was synthesized from a laying hen oviduct mRNA preparation enriched for conalbumin mRNA (con-mRNA). The dscDNA was inserted by blunt-end ligation into the Sal I site of plasmid pBR322 which had been repaired with DNA polymerase I to create Taq I sites on each side of the inserted fragment. After bacterial transformation, one hybrid recombinant, pBR322-con1, which contains the largest inserted dscDNA (about 2350 bp) was shown to hybridize specifically to the RNA which is translated into conalbumin. Electron microscopic examination of hybrid molecules between con-mRNA and pBR322-con1 DNA indicate that the inserted con-dscDNA is an almost full-length double-stranded transcript of conalbumin mRNA.

Animals↗
PubMed1979

The ovalbumin gene region: common features in the organisation of three genes expressed in chicken oviduct under hormonal control.

Two large DNA fragments overlapping the chicken ovalbumin gene have been isolated by molecular cloning. Analysis of these fragments provided a map of a 46,000-base pair region of the chicken genome. This region contains the complete ovalbumin gene (including its mRNA leader-coding sequence) and at least two other genes of unknown function. All three genes are orientated in the same direction and their expression in chicken oviduct is under hormonal control. The three genes share some sequence homologies, suggesting that duplications have occurred in the ovalbumin gene region in the course of evolution.

Animals↗
PubMed1979

Organisation and sequences at the 5' end of a cloned complete ovalbumin gene.

A clone which contains the complete chicken ovalbumin gene, including its leader coding sequences, has been isolated. From electron microscopic analysis of this DNA we conclude that the minimal size of the transcriptional unit for ovalbumin is 7.7 kilobases. The DNA sequence of the region surrounding the 5' end of the ovalbumin gene is presented. Comparison of this sequence with those of other eukaryotic genes reveals striking similarities, possibly related to a promoter region, approximately 30 base pairs upstream from the site coding for the 5' end of the mRNA.

Animals↗
PubMed1978

Organization of coding and intervening sequences in the chicken ovalbumin split gene.

The interruptions in the chicken ovalbumin gene which were reported previously (Breathnach, Mandel and Chambon, 1977) are shown to be due to the presence of intervening sequences which separate the messenger-coding sequences. We present evidence for an additional interruption of the gene, which, together with those reported earlier and by Garapin et al. (1978b), make a total of six intervening sequences. All of these intervening sequences are located in the DNA region that corresponds to the part of the ov mRNA which codes for amino acids. The seven coding fragments of the split ovalbumin gene are arranged in the same order and relative orientation as in the ovalbumin double-stranded cDNA. All the sequences coding for ov mRNA are contained in a chromosomal DNA region of 6000 bp, which is more than 3 times longer than ov mRNA. The general organization of the ovalbumin split gene is discussed.

Animals↗
PubMed1978

Ovalbumin gene: evidence for a leader sequence in mRNA and DNA sequences at the exon-intron boundaries.

Selected regions of cloned EcoRI fragments of the chicken ovalbumin gene have been sequenced. The positions where the sequences coding for ovalbumin mRNA (ov-mRNA) are interrupted in the genome have been determined, and a previously unreported interruption in the DNA sequences coding for the 5' nontranslated region of the messenger has been discovered. Because directly repeated sequences are found at exon-intron boundaries, the nucleotide sequence alone cannot define unique excision-ligation points for the processing of a possible ov-mRNA precursor. However, the sequences in these boundary regions share common features; this leads to the proposal that there are, in fact, unique excision-ligation points common to all boundaries.

Animals↗
PubMed1977

L-serine dehydratase from Arthrobacter globiformis.

1. L-Serine dehydratase (EC 4.2.1.13) was purified 970-fold from glycine-grown Arthrobacter globiformis to a final specific activity of 660micronmol of pyruvate formed/min per mg of protein. 2. The enzyme is specific for L-serine; D-serine, L-threonine and L-cysteine are not attacked. 3. The time-course of pyruvate formation by the purified enzyme, in common with enzyme in crude extracts and throughout the purification, is non-linear. The reaction rate increases progressively for several minutes before becoming constant. The enzyme is activated by preincubation with L-serine and a linear time-course is then obtained. 4. The substrate-saturation curve for L-serine is sigmoid. The value of [S]0.5 varies with protein concentration, from 6.5mM at 23microng/ml to 20mM at 0.23microng/ml. The Hill coefficient remains constant at 2.9.5 The enzyme shows a non-specific requirement for a univalent or bivalent cation. Half-maximal activity is produced by 1.0mM-MgCl2 or by 22.5mM-KCl. 6. L-Cysteine and D-serine act as competitive inhibitors of L-serine dehydratase, with Ki values of 1.2 and 4.9mM respectively. L-Cysteine, at higher concentrations, also causes a slowly developing irreversible inhibition of the enzyme. 7. Inhibition by HgCl2 (5micronM)can be partially reversed in its initial phase by 1mM-L-cysteine, but after 10 min it becomes irreversible. 8. In contrast with the situation in all cell-free preparations, toluene-treated cells of A. globiformis form pyruvate from L-serine at a constant rate from the initiation of the reaction, show a hyperbolic substrate-saturation curve with an apparent Km of 7mM and do not require a cation for activity.

Arthrobacter↗
PubMed1976

Nuclear binding of the estrogen receptor in whole uteri.

In order to show whether the estrogen complex (ER) in the intact cell binds to some nuclear component or whether it is in free equilibrium between the cytoplasm and the nucleus, we incubated intact uteri under conditions which increased the ratio of nuclear to cytoplasmic ER. These conditions included (a) the use of sucrose at concentrations greater than 0.75 M, (b) ethanol at 7.5% to 10%, or (c) 1 mM mercuric chloride or phenylmercuric acetate. Whereas (b) and (c) increased the ratio by preferentially denaturing the cytoplasmic ER, (a) caused ER to move from the cytoplasm into the nucleus by an undetermined mechanism. Uteri with a high ratio of nuclear to cytoplasmic ER were then washed, incubated in fresh "normal" incubation media, fractionated and the location of ER determined. If ER binding does occur in the nucleus, the high ratio of nuclear ER to cytoplasmic ER should be maintained, whereas if ER is in an equilibrium in the cell, ER should redistribute and re-establish the "normal" ratio. In all cases studied; i.e., after pre-treatment with sucrose at different concentrations, ethanol at different concentrations and either mercuric chloride or phenylmercuric acetate, the ratio of nuclear to cytoplasmic ER remained high, suggesting that ER binds to some nuclear component in intact cells.

Animals↗
PubMed1976

Current models of steroid hormone action: a critique.

In this review, we have traced the path of estradiol from its entry into the cell to the time of its release from the receptor. We feel that all of the current models are limited in one respect or another. We have examined most critically those currently most in vogue. The entry of estradiol into the cell is widely assumed to be simply a matter of diffusion. We have highlighted data that suggest the existence of a protein-mediated transport, but feel that the available data are too limited to make a definite conclusion.

Aldosterone↗
PubMedDate not supplied

The identification of cDNA clones that include the 3' end of mRNA.

A method is presented that facilitates the identification of cDNA clones corresponding to the polyadenylated 3' end of mRNA. It is based on the use of a poly dT probe that is synthesized by homopolymer extension of commercially available oligo dT. The method is shown to work in Southern blot analysis of plasmid preparations and in situ with colonies.

Blotting, Southern↗