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T C Bosch

Publications and source records attributed to T C Bosch.

34 records · Page 2Linked to original sources
PubMed1997

Cloning and characterization of BS-cadherin, a novel cadherin from the colonial urochordate Botryllus schlosseri.

The genomic DNA for a novel member of the cadherin family (BS-cadherin) was cloned and characterized from the colonial marine invertebrate, Botryllus schlosseri. Using a differential display of mRNA by means of PCR, a small cDNA fragment of 380 nucleotides was found to be specifically expressed in a colony undergoing allogeneic rejection processes, as compared with naive parts of the same genotype. This cDNA fragment was used as a probe to screen a genomic library of Botryllus schlosseri. A genomic fragment containing an ORF of 2718 nucleotides, with no introns, was isolated. The encoded protein exhibits a typical structure of cadherins; an extracellular domain with conserved repeated sequences (cadherin signatures), a single transmembrane domain and a conserved cytoplasmic tail region. The BS-cadherin amino-acid sequence shows 32-35% identity to mature classical cadherins type I, e.g., N-, P- and E-cadherin as well as mature classical cadherins type II, e.g., human cadherin-6, -8 and OB-cadherin. This cadherin represents a new cadherin gene family, evolutionarily distant to all other known classical cadherins.

Amino Acid Sequence↗
PubMed1997

Systematic isolation of peptide signal molecules regulating development in hydra: LWamide and PW families.

To isolate new peptide signal molecules involved in regulating developmental processes in hydra, a novel screening project was developed. Peptides extracted from the tissue of Hydra magnipapillata were systematically purified to homogeneity using HPLC. A fraction of each purified peptide was examined by differential display-PCR for its ability to affect gene expression in hydra. Another fraction was used to determine the tentative structure using an amino acid sequence analyzer and/or a mass spectrometer. Based on the results, peptides of potential interest were selected for chemical synthesis, followed by confirmation of the identity of the synthetic with the native peptides using HPLC. Using this approach, 286 peptides have been isolated, tentative amino acid sequences have been determined for 95 of them, and 19 synthetic peptides identical to native ones were produced. The 19 synthetic peptides were active in a variety of biological tests. For example, Hym-54 stimulated muscle contraction in adult polyps of hydra and sea anemone, Anthopleura fuscoviridis, and induced metamorphosis of planula, the larval stage, into polyps in a marine hydrozoan species, Hydractinia serrata. Another peptide, Hym-33H, inhibited nerve cell differentiation in hydra and induced tissue contraction in planula of Hydractinia serrata. The evidence obtained so far suggests that hydra contains a large number (>350) of peptide signal molecules involved in regulating developmental or other processes in cnidaria. These peptides can be isolated and their functions examined systematically with the new approach developed in this study.

Amino Acid Sequence↗
PubMed1995

Cloning of a ras-related gene from Hydra which responds to head-specific signals.

Members of the Ras family of proteins are important components of signal transduction pathways responding to external signals and leading to changes in cell behavior. Analysis of two ras-related genes in the phylogenetically old metazoan Hydra indicates that in normal animals both genes are expressed in all body regions of the polyp. Upon head removal, however, the transcript level of one of the two genes, ras2, decreases rapidly in the upper gastric region which is adjacent to the former head. The decrease is transient and specific for ras2, since no changes could be observed in the transcript level of the related ras1 gene or any other gene. The disappearance of the ras2 mRNA can be prevented completely by brief exposure of decapitated polyps to the protein kinase C activator TPA, which previously was shown to be capable of converting gastric tissue into head tissue [Müller, W.A. In: Othmer, H.G. (Ed.) Experimental and Theoretical Advances in Biological Pattern Formation. Plenum Press, New York, NY, 1993, pp. 237-253]. The finding that Hydra ras2 expression is strongly dependent on a signal from the head provides the first evidence for ras expression being regulated in pattern formation.

Amino Acid Sequence↗
PubMed1994

A SEM analysis of DMSO treated hydra polyps.

Scanning electron microscopy revealed that exposure of hydra polyps to DMSO at concentrations used for permeabilizing tissue results in striking changes in epithelial cell morphology. Epithelial cells from treated polyps rounded up in shape and formed numerous large blebs at the cell surface. Along the borders of epithelial cells numerous small projections became detectable. The DMSO-induced changes at the cell surface corresponded to drastic changes in the intracellular organization. No evidence could be found for DMSO induced opening of cell junctions and/or opening of the interstitial space. The results demonstrate that DMSO affects the morphology and intracellular organization of hydra epithelial cells. Thus, caution is necessary in interpreting cell behavior in DMSO treated tissue.

Animals↗
PubMed1994

Ks1, an epithelial cell-specific gene, responds to early signals of head formation in Hydra.

As a molecular marker for head specification in Hydra, we have cloned an epithelial cell-specific gene which responds to early signals of head formation. The gene, designated ks1, encodes a 217-amino acid protein lacking significant sequence similarity to any known protein. KS1 contains a N-terminal signal sequence and is rich in charged residues which are clustered in several domains. ks1 is expressed in tentacle-specific epithelial cells (battery cells) as well as in a small fraction of ectodermal epithelial cells in the gastric region subjacent to the tentacles. Treatment with the protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate (TPA) causes a rapid increase in the level of ks1 mRNA in head-specific epithelial cells and also induces ectopic ks1 expression in cells of the gastric region. Sequence elements in the 5'-flanking region of ks1 that are related to TPA-responsive elements may mediate the TPA inducibility of ks1 expression. The pattern of expression of ks1 suggests that a ligand-activated diacyglycerol second messenger system is involved in head-specific differentiation.

Amino Acid Sequence↗
PubMed1994

Hydra tropomyosin TROP1 is expressed in head-specific epithelial cells and is a major component of the cytoskeletal structure that anchors nematocytes.

A cDNA clone encoding a 253 amino acid tropomyosin was isolated from Hydra in a differential screen for head-specific genes. The Hydra tropomyosin gene, designated trop1, is a single copy gene, lacks introns and is strongly expressed in tentacle-specific epithelial cells. Analysis of protein synthesis in head and gastric tissue indicated a high rate of tropomyosin synthesis in head tissue. Immunolocalization of tropomyosin in tentacle tissue revealed a cushion-like tropomyosin-containing structure within battery cells at the base of nematocytes. The structure appears to form part of the cytoskeletal anchor for nematocytes. Tropomyosin cushions were also observed in epithelial cells along the body column, which contain mounted stenotele nematocytes.

Amino Acid Sequence↗
PubMed1992

Cloning and expression of a heat-inducible hsp70 gene in two species of Hydra which differ in their stress response.

A heat-inducible, intron-containing member of the hsp70 gene family has been isolated and characterized in Hydra magnipapillata and Hydra oligactis, two species previously shown [Bosch, T. C. G., Krylow, S. M., Bode, H. R. & Steele, R. E. (1988) Proc. Natl Acad. Sci. USA 85, 7927-7931] to differ in their stress response. The gene, hsp70.1, encodes a 654-amino-acid protein of predicted molecular mass 70 kDa with 78% amino acid identity to Xenopus HSP70. Northern-blot analysis revealed that polyps of H. oligactis accumulate significantly less hsp70.1 mRNA after heat shock than polyps of H. magnipapillata. In nuclear run-off experiments, we found that transcriptional induction of hsp70.1 expression in response to stress is similar in both species. Thus, the previously reported inability of H. oligactis to synthesize heat-shock proteins in response to stress is at least in part due to reduced stability of hsp70.1 mRNA during heat shock.

Amino Acid Sequence↗
PubMed1991

Interstitial stem cell proliferation in hydra: evidence for strain-specific regulatory signals.

We have examined the growth behavior of small numbers of interstitial stem cells transplanted into tissue of genetically unrelated strains of Hydra magnipapillata. We show that such stem cells, which are at low density following transplantation, proliferate more rapidly than the stem cells of the host, which are at normal density. The rapid proliferation is similar to the proliferation rate of stem cells transplanted into interstitial cell free tissue. The results suggest that stem cells transplanted into heterotypic tissue are unable to "sense" the presence of host stem cells and to adopt their growth rate to that of the surrounding cells. Thus, the feedback signal which negatively regulates stem cell growth as a function of stem cell density must be strain specific.

Animals↗
PubMed1990

Transplantation stimulates interstitial cell migration in hydra.

Migration of interstitial cells and nerve cell precursors was analyzed in Hydra magnipapillata and Hydra vulgaris (formerly Hydra attenuata). Axial grafts were made between [3H]thymidine-labeled donor and unlabeled host tissue. Migration of labeled cells into the unlabeled half was followed for 4 days. The results indicate that the rate of migration was initially high and then slowed on Days 2-4. Regrafting fresh donor tissue on Days 2-4 maintained high levels of migration. Thus, migration appears to be stimulated by the grafting procedure itself.

Animals↗
PubMed1990

Cloned interstitial stem cells grow as contiguous patches in hydra.

The migration of interstitial cells was analyzed during the growth of stem cell clones in vivo. The spatial distribution of cloned cells was analyzed at a time by which extensive migration of interstitial cells could have occurred. All interstitial cell clones were found to form large contiguous patches of cells. The results indicate that there is little migration of large interstitial cells in undisturbed tissue during normal growth. This finding is surprising since numerous grafting experiments have shown extensive migration of these cells. The implications of finding nonrandomly distributed stem cells are discussed.

Animals↗
PubMed1989

Structure and expression of STK, a src-related gene in the simple metazoan Hydra attenuata.

Both cDNA clones and a genomic DNA clone encoding a 509-amino-acid protein that is 64% similar to chicken pp60c-src were isolated from the simple metazoan Hydra attenuata. We have designated this gene STK, for src-type kinase. Features of the amino acid sequence of the protein encoded by the STK gene suggest that it is likely to be myristoylated and regulated by phosphorylation in a manner similar to that found for pp60c-src. The genomic sequence encoding the protein was found to be interrupted by at least two introns, one of which was located in a position identical to that of one of the introns in the chicken src gene. The STK gene was expressed during early development of H. attenuata and at high levels in the epithelial cells of adult polyps. Probing of Hydra proteins with an antibody to phosphotyrosine indicated that the major phosphotyrosine-containing protein in H. attenuata may be the STK protein itself. H. attenuata is the simplest organism from which a protein-tyrosine kinase gene has been isolated. The presence of such a gene in the evolutionarily ancient phylum Cnidaria suggests that protein-tyrosine kinase genes arose concomitantly with or shortly after the appearance of multicellular organisms.

Amino Acid Sequence↗
PubMed1988

Thermotolerance and synthesis of heat shock proteins: these responses are present in Hydra attenuata but absent in Hydra oligactis.

Organisms respond to environmental stress by synthesizing a small number of highly conserved heat shock proteins. In organisms as diverse as bacteria, plants, invertebrates, and vertebrates, synthesis of these proteins is directly correlated with the acquisition of thermotolerance. While studying the freshwater coelenterate hydra, we observed that Hydra oligactis was extremely sensitive to thermal stress. In contrast, the related species Hydra attenuata survives short-term exposure to high temperatures. Furthermore, after incubation at an elevated but nonlethal temperature, H. oligactis did not become thermotolerant. H. attenuata, however, acquired thermotolerance after such a preincubation. In H. attenuata the major heat shock protein was found to be 60 kDa in size. H. oligactis did not synthesize detectable levels of this protein or any new species of proteins in response to stress. Several other species of hydra were found to behave like H. oligactis in response to stress. Thus, these findings provide direct support for the hypothesis that heat shock proteins are required for stress tolerance and that the major heat shock protein in hydra does not have any effects on normal growth or physiology. The findings also indicate that the presence of a heat shock response might be related to the natural environment in which an organism lives.

Animals↗
PubMed1986

Male and female stem cells and sex reversal in Hydra polyps.

Single interstitial stem cells of male polyps of Hydra magnipapillata give rise to clones that differentiate either male or female gametes. To test the sexual stability of these clones, stem cells were recloned. The results indicate that stem cells from female clones are stable in their sexual differentiation capacity; male stem cells, by comparison, switch sexual phenotype at the rate of 10(-2) per cell per generation. As a result, female polyps contain only female stem cells; male polyps contain a mixture of male and female stem cells. A model is presented in which the sexual phenotype of Hydra polyps is controlled by (i) the switching rate of male and female stem cells and (ii) the repression of female differentiation by male stem cells.

Journal Article↗
PubMed1984

Growth regulation in Hydra: relationship between epithelial cell cycle length and growth rate.

The relationship between epithelial cell production and growth rate was investigated in Hydra attenuata under different feeding regimes. The increase of epithelial cell number was compared to the duration of the epithelial cell cycle using standard methods of cell cycle analysis. The results indicate that cell cycle changes accompanying changes in feeding regime are not sufficient to explain the altered growth rate. Under heavy feeding regimes, epithelial cell production equals tissue growth rate. At low feeding level or under starvation conditions the epithelial cell cycle lengthens and growth rate of epithelial cell population is slowed. However, the cell cycle changes are insufficient to account for the reduction in tissue growth and thus there is an effective overproduction of epithelial cells amounting to 10% per day. Evidence suggests that these excess cells are phagocytized by neighboring cells in the tissue. Thus phagocytosis is directly or indirectly involved in regulating the growth of hydra tissue.

Animals↗
PubMedDate not supplied

Decision making in interstitial stem cells of Hydra.

Interstitial stem cells in Hydra are a continuously proliferating and differentiating cell population. They represent a useful model system for studying mechanisms controlling stem cell differentiation. Here we review our current knowledge of the differentiation potential of these cells. Interstitial stem cells are multipotent and able to differentiate into several different cell types. The differentiation decisions appear to be controlled by positional signals and by the composition of the cellular environment. Since interstitial stem cells can be cultured in an in vivo environment and appear to be accessible to experimental manipulation by a range of new molecular techniques, an in vivo analysis of the molecular mechanisms underlying stem cell decision making can now be approached.

Amino Acid Sequence↗