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Biomedical subjects

G Hagen

Publications and source records attributed to G Hagen.

At least 55 records · Page 3Linked to original sources
PubMed1991

Expression of the uteroglobin promoter in epithelial cell lines from endometrium.

To understand the molecular mechanism of endometrial differentiation we have initiated an analysis of the uteroglobin promoter. Uteroglobin is normally expressed in endometrial tissues under the control of ovarian hormones. In gene transfer experiments with the Ishikawa cell line, derived from a human endometrial adenocarcinoma, we have identified several regions in the promoter of the uteroglobin gene that are responsible for its endometrium-specific expression. To evaluate the generality of these findings, we have begun cloning the promoter regions of potential endometrial markers, including the rat, mouse, and human uteroglobin gene. In the rat, expression of the uteroglobin-like gene, CC10, is dominant in the lung but is also observed in the endometrium of progesterone treated animals. A comparison of the 5'-flanking sequence of the rat and rabbit uteroglobin gene resulted in the detection of similarities and differences that could explain their differential expression in vivo. To substantiate these findings we have established several cell lines from rat endometrium using murine retroviral vectors containing a positive selection marker and various viral oncogenes, such as SV40 large T antigen, adenovirus E1A, and Ha-ras. Cell lines immortalized by SV40 T-antigen were subsequently transformed with the Ha-ras oncogene. Several cell lines exhibit properties of epithelial endometrial cells. Two cell lines generated with a temperature sensitive mutant of the SV40 large T-antigen grow as transformed cells at the permissive temperature, but differentiate upon shifting to the non-permissive temperature. These rat endometrial cell lines should be useful for the analysis of endometrium-specific gene expression and as model systems for endometrial carcinoma.

Animals↗
PubMed1990

Tissue-specific expression, hormonal regulation and 5'-flanking gene region of the rat Clara cell 10 kDa protein: comparison to rabbit uteroglobin.

The amino acid sequence of rat Clara Cell 10 kDa secretory protein (CC10) shows 55% identity to rabbit uteroglobin. In order to define the relationship between rat CC10 and rabbit uteroglobin in detail, the tissue-specific expression and hormonal regulation of rat CC10 mRNA was analyzed. We report that like rabbit uteroglobin, rat CC10 mRNA is expressed in lung and esophagus, as well as in uteri of estrogen- and progesterone-treated females. Expression of CC10 mRNA in lung is regulated by glucocorticoids. The similarity in expression pattern of rat CC10 mRNA and rabbit uteroglobin mRNA is reflected by a striking similarity in the 5'-flanking regions of the two genes. Despite this overall similarity, two regions of 0.3 kb and 2.1 kb are absent in the rat CC10 upstream gene region. The larger region includes a cluster of hormone receptor binding sites, believed to be responsible for differential regulation of rabbit uteroglobin by glucocorticoids and progesterone. Thus, while the sequence identities in the coding and 5'-flanking regions point towards a common ancestor for the uteroglobin and CC10 gene, later events (deletions/insertions) might have caused species-specific differences in their regulation.

Animals↗
PubMed1990

Ultrastructural findings in spongy degeneration of white matter in silver foxes (Vulpes vulpes). A naturally occurring demyelinating disease with oligodendrocyte vacuolation.

Spongy degeneration of white matter in silver foxes is a naturally occurring, hereditary disorder. We report ultrastructural findings in the upper cervical cord of five perfusion-fixed foxes that were examined between 5 weeks and 2 1/4 years after the onset of clinical signs. Large cytoplasmic vacuoles in oligodendrocytes were present in the foxes examined 5, 12 and 20 weeks after the onset. Other early features of the disease were severe vacuolation of myelin sheaths, demyelination, expansion of extracellular spaces and hypertrophy of astrocytes. Evidence of partial demyelination as well as demyelination of entire internodes was found. In the later stages of the disease, the vacuolation was largely resolved but a marked astrogliosis persisted and numerous remyelinated axons were present in the gliotic areas. Vacuolation of oligodendrocytes and partial demyelination has not previously been seen together in a single disease process. The relationship between oligodendrocyte vacuolation, myelin sheath vacuolation and demyelination is discussed. It is concluded that the present condition is due to a primary damage to oligodendrocytes; however, the underlying biochemical lesion is not known.

Animals↗
PubMed1990

On the basic structure of poly(glycerophosphate) lipoteichoic acids.

Poly(glycerophosphate) lipoteichoic acids from 24 Gram-positive bacteria of the genera Bacillus, Enterococcus, Lactobacillus, Lactococcus, Listeria, Staphylococcus, and the streptococcal pyogenic and oral group were analyzed. The 1,3-linked poly(glycerophosphate) structure was proved by analysis of glycerol and glycerophosphates after acid and alkaline hydrolysis. Using the molar ratios of glycolipid to phosphorus (A) and phosphomonoester to phosphorus after periodate oxidation followed by hydrazinolysis (B) or beta-elimination (C), we show that all lipoteichoic acids contain a single unbranched poly(glycerophosphate) chain and that the chain is uniformly phosphodiester-linked to C-6 of the nonreducing hexopyranosyl residue of the glycolipid moiety. On some chains minor phosphate-containing substituents were detected whose structure remains to be clarified. The lipoteichoic acids of enterococci and listeria strains were separated by hydrophobic interaction chromatography into glycolipid- and phosphatidylglycolipid-containing molecular species. The phosphatidylglycolipid moieties were structurally characterized after liberation from lipoteichoic acids with moist acetic acid. After periodate oxidation of lipoteichoic acids beta-elimination released both phosphatidic acid and the poly(glycerophosphate) chain. This indicates together with the sequence analysis of the released phosphatidylglycolipid that the phosphatidyl residue is located at C-6 of the reducing hexosyl residue of the glycolipid moiety and the poly(glycerophosphate) chain at C-6 of the nonreducing one. Together with earlier observations these results complete the evidence for the structural and possibly biosynthetic relationship between lipoteichoic acids and glycerophosphoglycolipids.

Carbohydrate Sequence↗
PubMed1990

Spongy degeneration of white matter in the central nervous system of silver foxes (Vulpes vulpes).

A disorder of central nervous white matter in Norwegian-bred silver foxes is described from the case histories of 21 clinically affected foxes. The main presenting sign of this disorder was caudal limb ataxia, which appeared between 2 1/2 and 4 months of age and progressed over the next 4-8 weeks. Only four affected foxes were allowed to live beyond this period, but they showed moderate to marked improvement. Light microscopic examination of specimens from 16 affected foxes necropsied between 3 1/2 and 6 1/2 months of age revealed lesions that were restricted to the white matter of brain and spinal cord. The lesions were characterized by a symmetrical spongy change with vacuoles of varying sizes and included significant myelin deficiency. There was a relative preservation of axons and nerve cells and no significant inflammation or vascular reaction. An astrocytic hypertrophy was usually associated with the spongy change. Ultrastructural examination of central nervous tissue from two, perfusion-fixed, 6-month-old foxes showed intramyelin vacuoles resulting from splitting of the myelin lamellae at the intraperiod line and was interpreted as indicating myelin edema. Expanded extracellular spaces and watery astrocytic processes also contributed to the vacuolar appearance. Astrocytic processes in affected areas were hypertrophic and contained abundant filaments. Although the 16 silver foxes had severe clinical signs, their lesions had features in common with the juvenile form of Canavan's disease in children and a spongy degeneration reported in Labrador Retrievers; however, the clinical course in the foxes was not uniformly progressive.

Animals↗
PubMed1989

Transcription, organization, and sequence of an auxin-regulated gene cluster in soybean.

We have characterized a soybean gene cluster that encodes a group of auxin-regulated RNAs (small auxin up RNAs). DNA sequencing of a portion of the locus reveals five homologous genes, spaced at intervals of about 1.25 kilobases and transcribed in alternate directions. At least three of the genes are transcriptionally regulated by auxin. An increase in the rate of transcription is detected 10 min after application of auxin to soybean elongating hypocotyl sections. Each of the genes contains an open reading frame that could encode a protein of 9 kilodaltons to 10.5 kilodaltons. Sequence comparisons among the five genes reveal several areas of high homology. Two regions of high homology begin about 250 base pairs upstream of the open reading frames and two regions of homology have been identified in sequences downstream of the open reading frames. One of the latter sequences occurs in the 3'-untranslated region of the RNAs. The other occurs far downstream, 618 base pairs to 741 base pairs from the stop codon. Conservation of these sequences among the five different genes suggests that they may be important for the regulation of expression of the genes.

Amino Acid Sequence↗
PubMed1989

Molecular approaches to understanding auxin action.

The plant hormone auxin is thought to be involved in diverse growth and developmental processes. The mechanisms by which the hormone exerts its effects are unknown. Recent evidence suggests that auxin can rapidly and specifically alter the expression of a select set of mRNAs. Auxin-responsive mRNAs from several plant systems have been isolated and characterized and, in a few cases, the corresponding gene sequence and organization have been elucidated. The rapid accumulation of auxin-responsive mRNAs appears to be regulated at both the transcriptional and post-transcriptional levels. Research efforts are currently focused on elucidating the cis-acting elements and trans-acting factors that mediate the regulation of genes by auxin. Additionally, the function of the auxin-responsive gene products and their relationship, if any, to auxin-regulated growth processes remain to be determined.

Gene Expression Regulation↗
PubMed1988

Regulation of expression of an auxin-induced soybean sequence by cadmium.

An auxin-regulated soybean sequence has been characterized and shown to be induced by the heavy metals cadmium, silver, and copper. Cadmium induces the accumulation of two size classes of mRNA: a 1-kilobase (kb) RNA class, which is the same size as the RNA class induced by auxin, silver, and copper, and a 1.4-kb RNA class. DNA sequence analysis of cDNA clones and a soybean genomic fragment has shown the presence of an intron in this gene. A restriction fragment probe isolated from the intron segment hybridizes specifically to the 1.4-kb mRNA. The transcription rate of this sequence is rapidly increased following exposure of soybean primary leaves to cadmium, as assayed by nuclear run-off transcription experiments. These results suggest that cadmium not only induces the transcription of a specific soybean sequence, but interferes with the processing of the precursor mRNA, resulting in the accumulation of the 1.4-kb mRNA precursor species.

Amino Acid Sequence↗
PubMed1985

Rapid induction of selective transcription by auxins.

Nuclei isolated from excised soybean plumules that were treated with 2,4-dichlorophenoxyacetic acid (2,4-D) were active in transcription of four auxin-regulated genes or DNA sequences, which have been described previously (G. Hagen, A. Kleinschmidt, and T. Guilfoyle, Planta 162:147-153, 1984). The rates of transcription of the auxin-responsive sequences were 10- to 100-fold greater with nuclei isolated from auxin-treated plumules than with those from untreated plumules. The transcriptional response was also observed with hypocotyls of intact soybean seedlings and hypocotyl sections, as well as with green bean and mung bean plumules that were treated with 2,4-D. Other auxins, including 2,4,5-trichlorophenoxyacetic acid, alpha-naphthaleneacetic acid, and indole-3-acetic acid, also induced the transcriptional response. Increased transcription rates were observed within 5 min after application of auxins to excised plumules, and half-maximal to maximal transcription rates were achieved by 15 min after application of auxins. As little as 10(-7) to 10(-8) M 2,4-D induced a transcriptional response, but maximal transcription rates were achieved at 10(-3) M 2,4-D. Brief treatment with the protein synthesis inhibitor cycloheximide did not inhibit the induction of transcription by auxins. These results clearly demonstrated that auxin-regulated gene expression is under rapid transcriptional control.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1984

Size heterogeneity of the largest subunit of nuclear RNA polymerase II. An immunological analysis.

Antibodies raised against the 180-kDa subunit of cauliflower RNA polymerase II bind selectively to the largest subunit of RNA polymerase II purified from a variety of plant species. The selective binding of this antibody to the largest RNA polymerase II subunit has allowed us to probe for the size of this subunit in crude cell extracts, in fractions containing partially purified RNA polymerase II, and in isolated nuclei. Fractions containing RNA polymerase II were subjected to electrophoresis in the presence of sodium dodecyl sulfate, blotted onto nitrocellulose, and blots were probed with antibody. Immunoglobulin complexes were revealed with 125I-Protein A. Published purification procedures result in rapid conversion of a 220-kDa subunit to a 180-kDa polypeptide, but purification at high pH (pH 9.0) retards this proteolysis. RNA polymerase II associated with isolated nuclei is largely protected from proteolytic degradation, and a 240-kDa polypeptide as well as a 220-kDa polypeptide can be detected. These results suggest that the 180-kDa subunit of RNA polymerase II arises artificially during cell lysis and enzyme purification, and that even the 220-kDa polypeptide may be a degradation product of a 240-kDa polypeptide in plants.

Animals↗
PubMed1984

Immunological studies on plant DNA-dependent RNA polymerases with antibodies raised against individual subunits.

Antibodies were raised against native soybean RNA polymerase II and individual subunits of RNA polymerase II purified from soybean, cauliflower, and wheat. These antibodies were used to study the immunological relationships of plant RNA polymerases I, II, and III at the subunit level. RNA polymerases I and II from soybean, I, II, and III from cauliflower and wheat, and II from turnip were purified to homogeneity, and enzyme subunits were separated on polyacrylamide gels containing sodium dodecyl sulfate. Separated RNA polymerase subunits were electrophoretically transferred to nitrocellulose, reacted with antibodies, and the immunoglobulin complexes were revealed by reaction with 125I-labeled Protein A. Antibodies directed against native soybean RNA polymerase II bind to all or most of the subunits of soybean and wheat RNA polymerase II and to the putative common subunits in RNA polymerases I and III. Antibodies directed against individual subunits of RNA polymerase II enzymes react specifically with the subunit to which the antibody was raised and to related or identical subunits in RNA polymerases I and III. These studies confirm the presence of common subunits in the three classes of nuclear RNA polymerase and provide information on analogous or related subunits within each class of enzyme purified from different plant species.

Animals↗
PubMed1984

Cloning and sequencing of the ribosomal RNA genes in maize: the 17S region.

The maize genes for the 17S, 5.8S, and 26S ribosomal RNAs (rRNAs) are located on chromosome 6 and consist of 9-kb sequences repeated about 5,000-10,000 times per 2C. One of these sequences was isolated from a lambda library containing maize Eco RI genomic segments. The sequence of the small-subunit (17S) RNA was determined using the M13 shotgun-dideoxy sequencing approach. The maize sequence was compared with nuclear rRNAs from yeast, Xenopus, and rat. Using these sequences, it is possible to identify tentatively the start and the end points of the sequence of the maize nuclear small subunit rRNA. This RNA has a length of 1809 nucleotides. The alignment of all four sequences for maximal homology allows us to identify regions within the rRNA that have been conserved during eukaryotic evolution.

Animals↗
PubMed1982

A transcriptionally active, covalently closed minichromosome of cauliflower mosaic virus DNA isolated from infected turnip leaves.

Purified nuclei from turnip leaves infected by cauliflower mosaic virus (CaMV) have been shown to contain a fraction of CaMV DNA that consists of covalently closed circular molecules; possesses a nucleosome structure, based on sensitivity to micrococcal nuclease; and contains nuclear RNA polymerase II that selectively transcribes the coding strand of CaMV DNA in vitro. Our results suggest that the transcriptionally active CaMV DNA is in the form of a minichromosome and that this DNA does not contain the site-specific discontinuities characteristic of the virion.

Chromosomes↗
PubMed1981

Complex organization of zein genes in maize.

We have examined the fragments of maize nuclear DNA that are homologous to three cloned cDNAs prepared from zein mRNA. Southern blots of high molecular weight (greater than 40 kb) maize nuclear DNA cleaved with BamHI, HindIII or EcoRI were hybridized to three zein cDNA plasmid probes. Multiple restriction fragments in a wide range of size classes were observed to hybridize with all three probes. Our results indicate the occurrence of families of genes in the maize genome that are related by their sequences to a given zein mRNA sequence.

DNA, Recombinant↗