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Biomedical subjects

V Schmid

Publications and source records attributed to V Schmid.

At least 37 records · Page 2Linked to original sources
PubMed1996

Mite allergy, clinical atopy, and restriction by HLA class II immune response genes.

From a community-based study cohort of 1812 elementary schoolchildren we selected 129 unrelated participants to investigate the relevance of HLA-class II molecules (DPB, DQB, and DRB) to the regulation of immune response to the mite allergen Der p 1 and to clinical atopic disorders. On the basis of skin prick test results validated by measurement of specific IgE, individuals were selected and divided into three groups: group I (n = 20), controls without detectable specific IgE to common inhalant allergens; group II (n = 22), children sensitized only to non-mite allergens; group III (n = 85), children sensitized to Der p 1. Clinical history of asthma, eczema, and hay fever was ascertained using standardized questionnaires. In total, 43 different HLA class II alleles (DPB, n = 19; DQB, n = 14; and DRB, n = 10) were determined by sequence-specific oligonucleotide typing with PCR-amplified DNA. We were not able to demonstrate significant differences in gene frequencies of any HLA class II allele between the group of mite-sensitized children and one of the other two groups. However, the presence of certain DRB- and DPB-haplotypes (DRB *0100/*0300/*1100 and DPB *0201/*0401) was significantly associated (p < or = 0.01) with a history of asthma, hay fever, and atopy (defined as a history of asthma and/or hay fever and/or eczema). Other haplotypes, including DQB *0303/*0503, DRB *0200/ *0700, and DPB 0402 were negatively associated with a history of eczema, hay fever, and atopy (p < or = 0.01). Thus, our findings do not suggest a relevance of HLA-class II molecules to mite allergy; however, some HLA class II haplotypes appear to be predictive of the incidence of atopic disorders.

Allergens↗
PubMed1995

Life stage and tissue-specific expression of the homeobox gene cnox1-Pc of the hydrozoan Podocoryne carnea.

We have isolated from the hydrozoan Podocoryne carnea a genomic clone and the corresponding cDNA of a homeobox gene. This gene, called cnox1-Pc, is most closely related to the lab class of homeobox genes. In the life cycle of P. carnea, which involves an asexually reproducing, sedentary polyp and a sexual planktonic medusa stage, we found cnox1-Pc transcripts specifically expressed in the medusa stage. Expression studies on isolated medusa organs and tissues indicate that the message is absent in the tentacles and the feeding and sexual organ of the medusa and present in the striated muscle cells. During medusa bud development, expression of cnox1-Pc can be correlated with the development of the striated muscle tissue, a cell type only found in the medusa. The results suggest that cnox1-Pc is involved in pattern formation of the medusa of P. carnea and might have a regulatory role in the differentiation of striated muscle.

Amino Acid Sequence↗
PubMed1995

An extracellular matrix protein of jellyfish homologous to mammalian fibrillins forms different fibrils depending on the life stage of the animal.

A monoclonal antibody generated against the isolated extracellular matrix (ECM) of the medusa Podocoryne carnea M. Sars (Coelenterata, Cnidaria, Hydrozoa) stains a fibrillar component of the Podocoryne ECMs in immunohistochemical preparations. The antigen shows a different staining pattern according to the type of ECMs from the animals life cycle. In ontogeny the epitope first appears after gastrulation in the planula larva as single widely dispersed small fibrils, which later accumulate to form a dense meshwork in the larval ECM. The distribution of the antigen strongly suggests an important role of the molecule to cover the biomechanical needs of the animal. In immunoblots one band with a size of 330 kDa is detectable in the polyp ECM, whereas in the outer ECM of the medusa a 340-kDa band is observed. Both the 330- and the 340-kDa bands appear when probed on the inner ECM of the medusa or on ECMs of the larva. The antibody was used to isolate a cDNA clone from an expression library. The deduced amino acid sequence of this cDNA fragment reveals a molecular structure composed of tandemly repeated epidermal growth factor-like repeats interrupted by a second cystein-rich motif first found in the latent transforming growth factor beta binding protein. Comparison of the sequence to the data bases indicates < 40% identity to human fibrillins. The presence of fibrillin-like beaded microfibrils in the ECM of P. carnea is furthermore demonstrated by electron microscopy after rotary shadowing. Our results demonstrate for the first time the existence of this noncollagenous interstitial ECM protein in invertebrates and suggest that the structure and the function of fibrillin have been conserved during evolution.

Amino Acid Sequence↗
PubMed1995

Transdifferentiation of isolated striated muscle of jellyfish in vitro: the initiation process.

Fragments of striated muscle tissue of Anthomedusae can be isolated and cultured. Without further treatment the isolated muscle fragments maintain the differentiated state. When treated with enzymes degrading the adhering extracellular matrix, drugs activating protein kinase C or substances destroying the actin cytoskeleton, dedifferentiation and DNA replication are initiated and transdifferentiation to several new cell types occurs. Initiation of DNA replication seems to be correlated with a disturbance of cell-ECM interactions. If muscle fragments are combined with isolated ECMs, cell migration onto the grafted ECMs occurs and DNA-replication and transdifferentiation are initiated in those cells which adhere to both, the native and the grafted ECM. If, however, the cells can stretch into a monolayer and adhere entirely to either the native or the grafted ECM, DNA-replication is inhibited. Carbohydrate moieties seem to be involved in mediating these cell-substrate interactions.

Animals↗
PubMed1994

The sequence of a cDNA encoding ribosomal protein S14 from the hydrozoan Podocoryne carnea reveals high evolutionary conservation.

We have isolated a cDNA clone encoding the ribosomal protein (Rsp) S14 from the hydrozoan Podocoryne carnea. The complete nucleotide sequence was determined. Comparison of the deduced amino-acid sequence to those of the Rsp S14 of other species revealed a high evolutionary conservation. An elevated transcription of the Rsp gene in isolated striated muscle tissues is suggested.

Amino Acid Sequence↗
PubMed1993

Actin-encoding genes of the hydrozoan Podocoryne carnea.

We have isolated and characterized one genomic clone and five actin-encoding cDNA clones of Podocoryne carnea. The complete nucleotide (nt) sequences of the genomic clone and two cDNA clones were determined. The genomic clone contains two introns at positions also found in actin-encoding genes (Act) of other species. The transcription start point has been mapped, and the promoter sequences CAAT and TATA were identified. The sequenced Act cDNA clones encode identical proteins. The deduced amino acid (aa) sequence differs from the genomic clone in 5 aa residues. All aa substitutions occur in a small region between aa 211 and 303. This variable region has also been sequenced from the remaining Act cDNA clones. From these data, it was concluded that the six Act genes probably code for only two actin proteins (Act). The nt sequences were compared to those of Act from other species. A closer relationship of coelenterate Act to deuterostome than to protostome Act is proposed.

Actins↗
PubMed1993

Characterization of a tropomyosin cDNA from the hydrozoan Podocoryne carnea.

A cDNA clone from the hydrozoan Podocoryne carnea was characterized. It consists of an open reading frame of 726 nt flanked by a 84 nt 5' and a 307 nt 3' untranslated region. The corresponding gene exists apparently as a single copy. The transcript is ubiquitously expressed in the polyp and the medusa stage. Several features of the predicted peptide sequence indicate a relationship to tropomyosins. At the amino acid level it shares 26-30% identical residues with other invertebrate and vertebrate tropomyosin sequences.

Amino Acid Sequence↗
PubMed1993

Mechanochemical interactions between striated muscle cells of jellyfish and grafted extracellular matrix can induce and inhibit DNA replication and transdifferentiation in vitro.

Striated muscle tissue of jellyfish was isolated with its adhering extracellular matrix (ECM) and cultured. Without further treatment the cultured muscle cells maintain their differentiated state. If, however, the isolated tissues are combined with cell-free ECM from the jellyfish or its polyp, DNA replication and proteolytic activity are induced followed by transdifferentiation into RF-amide-positive nerve cells. Changes in the mechanochemical interactions between the cells and the grafted ECM seem to induce the signals which lead to transdifferentiation. If the isolates are combined with small floating pieces of ECM most cells will leave their own ECM and overgrow the ECM graft. All cells in the combinations will then transdifferentiate. If the isolates are grafted onto large pieces of ECM kept permanently stretched on glass, a majority of cells will migrate onto the grafted ECM where they form a flat monolayer. In this case, however, DNA replication and transdifferentiation occurs mainly in those cells which have remained on or near their own ECM. Labeling experiments with [3H]-thymidine demonstrate that initiation of DNA replication occurs first in those cells which bridge from the native ECM to the grafted ECM. On the other hand inhibition of DNA replication and transdifferentiation is generally suppressed whenever tissues are allowed to form a monolayer of well-stretched cells. From these observations we conclude that mechanochemical interactions between the muscle cells and their substrate are responsible for both activation and inhibition of DNA replication and transdifferentiation.

Animals↗
PubMed1993

Life stage specific expression of a myosin heavy chain in the hydrozoan Podocoryne carnea.

In order to study life stage specific gene-expression and also to investigate the molecular components of jellyfish muscle we cloned a tissue specifically expressed cDNA of the metagenetic hydrozoan Podocoryne carnea. A monoclonal antibody was made that reacts with the filaments of striated muscle of the medusa stage. The mAb detects a protein of 220 kDa in Western blots. The antibody was used to clone a cDNA from an expression library. Sequence analysis showed that the clone codes for the rod part of a myosing heavy chain (MHC). Surprisingly, the sequence is more similar to MHCs from striated muscle than to smooth muscle or non-muscle MHCs from either invertebrates or vertebrates. A particularly well conserved region, which may be correlated to a function in striated muscle, was found. Expression studies showed that the corresponding RNA is only present in the striated muscle cells of the medusa. During medusa development, the transcript became detectable at the same time as muscle differentiation becomes visible in the electron microscops.

Amino Acid Sequence↗
PubMed1990

The proportion altering factor (PAF) and the in vitro transdifferentiation of isolated striated muscle of jellyfish into nerve cells.

The effect of proportion altering factor (PAF) on the transdifferentiation of isolated striated muscle into RFamide-positive nerve cells was investigated. The factor reduces incorporation of 3H-thymidine into replicating DNA; the effect is concentration-dependent and reversible. Transdifferentiation to nerve cells increases by up to 60% if PAF is applied shortly before or at the time of initiation of DNA synthesis. When treatment was terminated 4 h before the start of S-phase or when PAF was applied at the peak of S-phase no increase in nerve cell formation was observed.

Animals↗
PubMed1988

Species specificity in cell-substrate interactions in medusae.

A new system is described for the study of ECM-tissue interactions, using the ECM (called mesogloea) of various cnidarians and isolated striated muscle and endodermal tissue of jellyfish. The mesogloea consists mainly of water and collagen. It is present in all cnidarians and can be isolated without enzyme treatment. It can be used as a substrate to which cells and tissues adhere and on which they spread and migrate. Tissues of striated muscle and endoderm adhere and spread not only on mesogloea from regions they normally cover, but also from other regions of the animal. However, adhesion and spreading are highly species-specific. Species-specific adhesion is found throughout the whole mass of mesogloea even at regions where cells do not occur naturally. The cell adhesion factor can be extracted from the mesogloea so that the mesogloea no longer shows any cell adhesion properties. The extract consists mainly of a cysteine-containing collagen.

Animals↗
PubMed1988

The jellyfish and its polyp: a comparative study of gene expression monitored by the protein patterns, using two-dimensional gels with double-label autoradiography.

The life cycle of Podocoryne carnea (Coelenterata, Anthomedusae) shows several distinct stages which differ considerably in terms of their ecology, morphology, cellular composition, and ultrastructure. Previously these stages had even been described as separate species. Using two-dimensional gel electrophoresis and a new method of double-label autoradiography, we show here for the first time for metagenic hydrozoans that only minor differences in gene expression exist between the various life cycle stages. Our results demonstrate the high resolution power of these techniques and show that the different life stages of P. carnea remain rather similar on the protein level. Most of the prominent spots of the two-dimensional gel protein patterns are common to all stages studied. These data show that the hydrozoan life cycle and development are regulated by only minor distinctions in gene expression which possibly explains the great morphogenetic repertoire of these animals described in many studies.

Animals↗
PubMed1988

Transdifferentiation from striated muscle of medusae in vitro.

We have established an in vitro transdifferentiation and regeneration system which is based entirely on mononucleated striated muscle cells. The muscle tissue is isolated from anthomedusae and activated by various means to undergo cell cycles and transdifferentiation to several new cell types. In all cases DNA-replication is initiated and the division products are smooth muscle cells, characterized by their ultrastructure and monoclonal antibodies, and nerve/sensory cells, characterized by their ultrastructure and FMRFamide-staining. Both cell types are found at a 1:1 ratio after the first division. The nerve cells stop to replicate, whereas the smooth muscle cells continue and keep producing in each successive division a smooth muscle cell and a nerve cell. The observed data indicate that smooth muscle cells behave like stem cells. Depending on the destabilization and culturing methods, some isolated muscle tissue will form a bilayered fragment and within only two cell cycles manubria (the feeding and sexual organ) or tentacles will regenerate. In this case six to eight new non-muscle cell types have been formed by transdifferentiation.

Animals↗