PubMed Health⌕ Search

Biomedical subjects

M Herzog

Publications and source records attributed to M Herzog.

At least 19 recordsLinked to original sources
PubMed1995

GASA, a gibberellin-regulated gene family from Arabidopsis thaliana related to the tomato GAST1 gene.

A multiple gene family of at least four members, related to a GA-stimulated transcript (GAST1) from tomato, was characterized in Arabidopsis thaliana by analysing four related cDNAs, named GASA1 to GASA4. The corresponding peptides display comparable structural features: (1) a putative signal peptide of 18 to 23 residues; (2) a highly divergent hydrophilic region of about 22 amino acids; (3) a conservative 60 amino acid C-terminal domain containing 12 cysteines. This organization has also bean shown in two related peptides from tomato, GAST1 found in shoots and RSI-1 found in early lateral roots. Southern blot hybridization patterns showed single-copy genes for all four members of the GASA family. Accumulation of the various transcripts, monitored by northern blot hybridization, indicated that the various genes are expressed differentially in plant organs: Specific mRNAs were mostly detected in flower buds and immature siliques in the case of GASA1, in siliques and dry seeds in the case of GASA2 and 3, and in growing roots and flower buds in the case of GASA4. At least two of the GASA genes are activated in GA-deficient mutant ga5, as early as 4 to 8 h after spraying with 50 microM GA3. The complex patterns of expression and regulation of the various genes suggest that the related peptides are involved in a developmental regulation process in Arabidopsis.

Amino Acid Sequence↗
PubMed1992

Calponin and SM 22 isoforms in avian and mammalian smooth muscle. Absence of phosphorylation in vivo.

Calponin is a basic smooth-muscle-specific protein capable of binding to F-actin, tropomyosin and calmodulin in vitro. Using two-dimensional gel electrophoresis, we show that calponin exists as multiple isoelectric variants in avian and mammalian tissues. During chick embryogenesis, one isoform is expressed in gizzard that shows a pI identical to the most basic adult alpha variant; around 10 d after hatching multiple isoforms then appear. SM 22 [Pearlstone, J. R., Weber, M., Lees-Miller, J. P., Carpenter, M. R. & Smillie, L. B. (1987) J. Biol. Chem. 262, 5985-5991], which has sequence-motifs related to calponin, displays a similar isoform pattern during development; one isoform (alpha) is present in the embryo and three in the adult. In living smooth-muscle strips from chicken gizzard and guinea pig taenia coli, labelled with 32PO4, no phosphate incorporation could be detected in any of the calponin or SM 22 isoforms during either contraction or relaxation. From the additional observation that antibodies against phosphoserine also failed to label calponin and SM 22 in two-dimensional gel immunoblots, we conclude that the multiple isoforms do not arise via differential phosphorylation. These results support the claim [Barany, M., Rokolya, A. & Barany, K. (1991) FEBS Lett. 279, 65-68] that calponin phosphorylation is not involved in smooth muscle regulation in vivo, as has been suggested from in vitro studies [Winder, S. J. & Walsh, M. J. (1990) J. Biol. Chem. 265, 10148-10155]. In vitro translation of porcine and chicken smooth-muscle mRNA produced only a single (alpha) isoform of calponin, suggesting that the adult isoforms do not derive from multiple gene products; in the same assay two polypeptides appeared in the position of SM 22, one corresponding to the alpha isoform and a second more basic spot, not observed in tissue samples. Whereas calponin and SM 22 appear synchronously during smooth muscle differentiation in vivo, SM 22 is not fully down-regulated like calponin, metavinculin and heavy-caldesmon in smooth muscle cells in culture, pointing to a differential regulation of expression of the alpha SM 22 isoform during smooth-muscle phenotype modulation in vitro.

Animals↗
PubMed1992

Mitochondrial rps14 is a transcribed and edited pseudogene in Arabidopsis thaliana.

We have isolated and analysed a 2 kb region of the mitochondrial genome of Arabidopsis thaliana (Columbia) showing a high level of nucleotide identity with the mitochondrial (mt) rps14 small-subunit ribosomal protein gene from Oenothera berteriana and Vicia faba, as well as with an open reading frame (ORF) located upstream of the nad3 locus in O. berteriana. The rps14 locus is present as a single copy in the A. thaliana mt genome and has a translational stop codon located near the initiation codon, as well as a deletion of one nucleotide that disturbs the coding sequence. The cloning and sequencing of nine amplified mt rps14 cDNAs clearly demonstrated that this gene is transcribed and that the mRNA precursors are edited at three positions, all involving C-to-U conversions. No editing events changing the stop codon and restoring the correct coding sequence were witnessed within the 9 individual cDNA clones. Therefore, we conclude that the single rps14 sequence of the mitochondrial genome from A. thaliana is in fact a pseudogene that is transcribed and edited but not translated.

Amino Acid Sequence↗
PubMed1992

Nucleocapsid specific T and B cell responses in humans after rabies vaccination.

The importance of the immune response directed to the internal component of the rabies virus, the nucleocapsid (NC), was evaluated in humans after rabies vaccination. T cell activation was measured with a bulk proliferative assay and relative frequencies of circulating NC-specific PBL were calculated with the limiting dilution technique. Vaccinees were classified into two groups: NC responders and NC non-responders. In NC responders, the frequency of NC-specific circulating lymphocytes was up to 6 times higher than the frequency of virus-specific lymphocytes. In non-responders, NC-specific lymphocytes were up to 25 times less common than virus-specific ones. The NC capacity to induce a secondary antibody response was tested in vitro. After a stimulation with complete virus, lymphocytes originating from donors vaccinated with tissue culture vaccine produced a secondary antibody-response composed mainly of glycoprotein-specific neutralizing antibodies, whereas lymphocytes from suckling mouse brain vaccines produced essentially NC-specific antibodies. This result confirmed the serological status of suckling mouse brain vaccinees, who usually developed high titres of NC-specific antibodies. After an in vitro NC stimulation, lymphocytes collected from NC responders produced not only NC-specific antibodies, provided they have NC-specific B cells at the time of blood sampling, but most surprisingly, they also produce glycoprotein-specific neutralizing antibodies. This finding indicates that NC free of glycoprotein is capable, in some individuals, of boosting an heterologous glycoprotein response.

Antibodies, Viral↗
PubMed1992

[Initial clinical experiences with the photodynamic therapy (PDT) of oral cavity carcinomas].

Photodynamic therapy (PDT) is based on the selective accumulation of photosensitizing agents in tumor tissues. Activation of the photosensitizer with ligh of suitable wavelength leads to tumor destruction preserving healthy tissues. 13 carcinomas stage T1 and T2 of the oral cavity in men were treated. Necroses of a depth from 1.5 to 6 mm occurred regularly. Therefore photodynamic therapy seems to be suitable to treat small, superficial cancers of the oral cavity, especially, if the tumors are multilocated.

Carcinoma↗
PubMed1991

Molecular cloning and immunolocalization of two variants of the major basic nuclear protein (HCc) from the histone-less eukaryote Crypthecodinium cohnii (Pyrrhophyta).

Two clones that encode variants (HCc1 and HCc2) of the major basic nuclear protein of the dinoflagellate Crypthecodinium cohnii, were identified by immunoscreening of a cDNA expression library. The first clone carries a full-length cDNA with an open reading frame (HCc1) encoding 113 amino acids. The cDNA from the second clone lacks some of the 5' end, and the coding sequence is only 102 residues. The two proteins display 77% sequence similarity and their NH2-ends are homologous to the NH2-peptide of the HCc protein determined by P. Rizzo. The amino acid composition, which confirms the basic nature of lysine-rich HCc proteins, differs markedly from other known DNA-binding proteins such as histones, HMGs or prokaryotic histone-like proteins. No convincing homology was found with other proteins. HCc antigens were localized on C. cohnii by immunofluorescence, and by electron microscopy (EM) with immunogold labelling. HCc proteins are mainly detected at the periphery of the permanently condensed chromosomes, where active chromatin is located, as well as in the nucleolar organizing region (NOR). This suggests that these basic, non-histone proteins, with a moderate affinity for DNA, are involved at some level in the regulation of gene expression.

Amino Acid Sequence↗
PubMed1991

A molecular phylogeny of dinoflagellate protists (pyrrhophyta) inferred from the sequence of 24S rRNA divergent domains D1 and D8.

The sequence of two divergent domains (D1 and D8) from dinoflagellate 24S large subunit rRNA was determined by primer extension using total RNA as template. Nucleotide sequence alignments over 401 bases have been analyzed in order to investigate phylogenetic relationships within this highly divergent and taxonomically controversial group of protists of the division Pyrrhophyta. Data are provided confirming that dinoflagellates represent a monophyletic group. For 11 out of the 13 investigated laboratory grown species, an additional domain (D2) could not be completely sequenced by reverse transcription because of a hidden break located near its 3'-terminus. Two sets of sequence alignments were used to infer dinoflagellate phylogeny. The first [199 nucleotides (nt)] included conservative sequences flanking the D1 and D8 divergent domains. It was used to reconstruct a broad evolutionary tree for the dinoflagellates, which was rooted using Tetrahymena thermophila as the outgroup. To confirm the tree topology, and mainly the branchings leading to closely related species, a second alignment (401 nt) was considered, which included the D1 and D8 variable sequences in addition to the more conserved flanking regions. Species that showed sequence similarities with other species lower than 60% on average (Knuc values higher than 0.550) were removed from this analysis. A coherent and convincing evolutionary pattern was obtained for the dinoflagellates, also confirmed by the position of the hidden break within the D2 domain, which appears to be group specific. The reconstructed phylogeny indicates that the early emergence of Oxyrrhis marina preceded that of most Peridiniales, a large order of thecate species, whereas the unarmored Gymnodiniales appeared more recently, along with members of the Prorocentrales characterized by two thecal plates. In addition, the emergence of heterotrophic species preceded that of photosynthetic species. These results provide new perspectives on proposed evolutionary trees for the dinoflagellates based on morphology, biology, and fossil records.

Animals↗
PubMed1991

Nucleolar localization of rRNA coding sequences in Prorocentrum micans Ehr. (dinomastigote, kingdom Protoctist) by in situ hybridization.

To define the molecular mechanisms of ribosome biogenesis and to find out in which nucleolar compartment transcription of rDNA occurs, we have performed in situ hybridization (ISH) of RNase-treated cryosections using biotinylated rRNA coding sequences as a probe and the eukaryotic dinoflagellate nucleolar system as a model. Recent data from ISH of eukaryotic ribosomal genes by electron microscopy (EM) has so far failed to establish a consensus which clearly defines the function of the three compartments of the nucleolus. Dinomastigote protoctists are the only known eukaryotes whose chromatin is totally devoid of nucleosomes. Their chromosomes remain permanently condensed during the entire cell cycle and active nucleoli arise from an unwound part of some of the otherwise compact chromosomes. In this work, DNA-DNA hybrids were detected either by fluorescent avidin or by indirect immunogold staining procedures in EM; this is the first use of cryosections to detect hybrids in EM not only in the nucleolus sensu lato but also in a dinomastigote cell. Coding sequences of ribosomal genes were detected both in the periphery of the nucleolar organizer region (NOR), which corresponds to the unwound part of the nucleolar chromosome, and in the proximal part of the fibrillo-granular (FG) region. These results suggest that the rRNA gene transcription predominantly occurs at the periphery of the NOR where the coding sequences are located. A predictive model summarizes and allows discussions and comparisons with other eukaryotes in which nucleolar mechanisms were previously studied. This leads to the conclusion that dinoflagellate cells constitute an excellent model for the study of the functional structure of the eukaryotic nucleolus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Leading edge movement and ultrastructure in mouse macrophages.

The first event in the process of translocation of a cell over a substrate is the forward protrusion of a thin layer of cytoplasm, sometimes referred to as the leading edge. To gain more direct information on structural reorganizations associated with protrusion we have documented the ultrastructure of the actin cytoskeleton of mouse macrophages whose history of locomotion prior to fixation for electron microscopy had been recorded by video microscopy. It is shown that rapid protrusion is associated with the formation of a dense, diagonal network of actin filaments, lacking organized bundles. In cell edges that showed minor fluctuations back and forth over a period of 30 sec or more no dense meshworks were found: instead, a loose peripheral bundle of actin filaments was commonly observed. Cell edges that first protruded and then retracted showed a similar ultrastructure to those that exhibited only forward movement, but the width of the leading edge meshwork was, by comparison, reduced. Measurements showed that there was an approximate correlation between the leading edge mesh width and the net forward translocation observed during the terminal 30 sec, up to fixation. The results are discussed in relation to present concepts of the protrusion mechanism.

Actins↗
PubMed1991

T and B cell human responses to European bat lyssavirus after post-exposure rabies vaccination.

T and B cell human responses to European bat lyssavirus (EBL1) induced by post-exposure rabies vaccination (PM virus vaccine) were evaluated by measuring plasmatic titres of EBL1-specific neutralizing antibodies; specific EBL1-binding antibodies; and proliferation indices of peripheral blood lymphocytes stimulated in vitro with EBL1. These parameters for vaccination efficacy were compared with those obtained with vaccine-related viruses (CVS and ERA) and with a non-vaccine-related virus. Mokola virus, the last implicated in vaccination failures. Twenty-two patients exposed to rabies risk who received a reduced rabies post-exposure vaccination were involved in the study. On day 21, vaccine induced CVS-specific neutralizing antibodies in all patients; but EBL1-specific neutralizing antibodies were induced in only 73% of patients. No vaccine had Mokola-specific neutralizing antibodies. Patients having EBL1-specific neutralizing antibodies were usually those in whom vaccination induced high titres of CVS-specific neutralizing antibodies. On day 21, peripheral blood lymphocytes of 86% of patients could be restimulated in vitro with vaccine, 43% with EBL1 and 45% with Mokola. Patients exhibiting a high vaccine-specific proliferation response more likely developed an EBL1- or a Mokola-specific proliferative response. No correlation was found between T and B cell responses. Rabies vaccination induced neither T nor B cell EBL1-specific responses in 22% of patients.

Adult↗
PubMed1991

[Circadian rhythm of the toxicokinetics and toxicodynamics of the plant protection substance dinitro-ortho-cresol in rabbits].

Results from chronotoxicological investigations with the plant protection chemical DNOC has been described and judged. It has been studied hyperthermia caused by i.v. application of 7.5 mg/kg body weight on rabbits to 6 different times, starting at 4 a.m. with 4-hours-intervals as well as the dose-effect relation in each case with 3 doses to the time of application at 12 a.m., 6 p.m., 12 p.m. and 6 a.m. and the renal DNOC excretion after a dose of 10 mg/kg body weight. There was found a time dependent rhythm in all experiments. Acrophase of hyperthermia is placed in the middle of the phase of activity of the animals at 12 p.m., however it depends on the dose. The results are showing, that the position of acrophase by constant environmental factor is neither a substance specific nor an animal specific constant.

Animals↗
PubMed1990

Isolation and sequence of a tropomyosin-binding fragment of turkey gizzard calponin.

Limited chymotryptic cleavage of turkey gizzard calponin yields a 13 kDa fragment which could be purified by its ability to bind to Sepharose-immobilized tropomyosin. This 13 kD polypeptide is shown to be derived from a 22 kDa fragment. Complete amino acid sequence analysis of the 13 kD and 22 kD fragments reveals high homology with the formerly characterized smooth muscle-specific protein SM22 alpha (Pearlstone, J.R., Weber, M., Lees-Miller, J.P., Carpenter, M.R. and Smillie L.B., 1987, J. Biol. Chem. 262, 5985-5991) and the product of gene mp20 of Drosophila (Ayme-Southqate, A., Lasko, P., French, C, and Pardue, M.L. [(1989) J. Cell Biol. 108, 521-531]. Futhermore we recognize sequence elements of a putative actin-binding domain of alpha-actinin, the calpactin I or p 36 sequence, and a consensus motif present in the repeats of the gene product of the candidate unc-87 gene of C. elegans (S.D. Goetinck and R.H. Waterston, personal communication).

Amino Acid Sequence↗
PubMed1990

Smooth muscle specific expression of calponin.

Calponin is an actin-, calmodulin-, and tropomyosin-binding protein that has been isolated from smooth muscle tissue. Using a monoclonal antibody specific for avian calponin, we demonstrate a differentiation-linked increase in calponin expression in embryonic chick gizzard. Cultivation of gizzard smooth muscle cells in vitro resulted in a down-regulation of calponin expression after the first 48 h that was paralleled by a loss of synthesis of metavinculin and the high molecular weight isoform of caldesmon. In early cultures of smooth muscle cells calponin was localised in the actin-containing stress fibres but labelling was restricted to the central parts of the actin cytoskeleton. Calponin expression is suggested as a potentially useful index of smooth muscle differentiation.

Animals↗
PubMed1990

Basic nuclear proteins of the histone-less eukaryote Crypthecodinium cohnii (Pyrrhophyta): two-dimensional electrophoresis and DNA-binding properties.

Unlike typical eukaryotes, the Dinoflagellate Crypthecodinium cohnii does not contain histones but six major basic, low molecular weight nuclear proteins which represent only 10% of the DNA mass and differ from histones in their electrophoretic and DNA-binding properties. These proteins are resolved in two-dimensional electrophoresis (AUT-PAGE x SDS-PAGE). Three proteins with an apparent molecular mass of 16, 16.5 and 17 kDa (p16, p16.5 and p17) are present in addition to the major 14 kDa basic nuclear component (HCc). HCc itself is resolved in three proteins (alpha, beta and gamma). When the proteins are not reduced with 2-mercaptoethanol before 2D-PAGE, the migration of HCc alpha, beta and gamma is modified in a way which suggests the formation of both inter- and intramolecular disulfide bridges and thus, the presence of at least two cysteines. The amino-acid analysis of HCc proteins resolved in 2D gels confirms that they are lysine-rich. HCc alpha, beta and gamma as well as p16, p16.5 and p17 are removed from isolated chromatin with 0.6 M NaCl, indicating that their affinity for DNA in vivo is lower than that of core histones. Furthermore, in vitro, they bind more tightly to single-stranded than to double-stranded DNA.

Animals↗
PubMed1990

Characterization of amplification core and esterase B1 gene responsible for insecticide resistance in Culex.

Organophosphorus insecticide (OP) resistance in several Culex species is associated with increased esterase activity resulting from amplification of the corresponding structural gene. In Culex pipiens quinquefasciatus, high levels of OP resistance (approximately 800 times) are due to the esterase B1 gene, which is amplified at least 250-fold. This gene has now been sequenced, and the structure of the amplification unit (amplicon) encompassing the structural gene has been partially characterized. The inferred amino acid sequence of the enzyme revealed regions of strong homology with other eukaryotic serine-esterases, such as cholinesterases, which are the target of OPs. The amplicon covers at least 30 kilobases and contains a constant and highly conserved "core" of 25 kilobases. This core carries a single copy of the esterase gene (2.8 kilobases) as well as other sequences that are present as single or low number copies in the genomes of mosquitoes lacking overproduction of the esterase B1 protein. In the amplicon, the esterase gene is framed by two DNA sequences that are repeated in other parts of the genome of resistant mosquitoes and found in the genome of susceptible mosquitoes but not near the esterase B1 gene. It is suggested that these repetitive sequences may have a role in the amplification process.

Amino Acid Sequence↗
PubMed1990

Supercontracted state of vertebrate smooth muscle cell fragments reveals myofilament lengths.

Isolated cell preparations from chicken gizzard smooth muscle typically contain a mixture of cell fragments and whole cells. Both species are spontaneously permeable and may be preloaded with externally applied phalloidin and antibodies and then induced to contract with Mg ATP. Labeling with antibodies revealed that the cell fragments specifically lacked certain cytoskeletal proteins (vinculin, filamin) and were depleted to various degrees in others (desmin, alpha-actinin). The cell fragments showed a unique mode of supercontraction that involved the protrusion of actin filaments through the cell surface during the terminal phase of shortening. In the presence of dextran, to minimize protein loss, the supercontracted products were star-like in form, comprising long actin bundles radiating in all directions from a central core containing myosin, desmin, and alpha-actinin. It is concluded that supercontraction is facilitated by an effective uncoupling of the contractile apparatus from the cytoskeleton, due to partial degradation of the latter, which allows unhindered sliding of actin over myosin. Homogenization of the cell fragments before or after supercontraction produced linear bipolar dimer structures composed of two oppositely polarized bundles of actin flanking a central bundle of myosin filaments. Actin filaments were shown to extend the whole length of the bundles and their length averaged integral to 4.5 microns. Myosin filaments in the supercontracted dimers averaged 1.6 microns in length. The results, showing for the first time the high actin to myosin filament length ratio in smooth muscle are readily consistent with the slow speed of shortening of this tissue. Other implications of the results are also discussed.

Actin Cytoskeleton↗