Structure of neuropeptide precursors in cnidaria.
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Amino Acid Sequence↗
Biomedical subjects
G Plickert
Publications and source records attributed to G Plickert.
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↗
Proportion-altering factor (PAF) stimulates nerve cell formation in Hydractinia echinata.
The low-molecular weight proportion altering factor (PAF) from colonial hydroids has general animalizing effects on morphogenesis in hydroid development. On the cellular level, the factor stimulates the formation of nerve cells in several developmental stages of Hydractinia echinata. Treatment during metamorphosis yielded a fivefold increase in the number of nerve cells with FMRF-amide-like immunoreactivity. In non-metamorphosing planula larvae, PAF triggered the differentiation of nerve cells that normally develop only upon initiation of metamorphosis and that occur in the polyp stage. After post-metamorphic treatment of young primary polyps, nerve cell numbers increased to 2.5 times the normal value.
Animals↗
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↗
Proliferation kinetics and cell lineages can be studied in whole mounts and macerates by means of BrdU/anti-BrdU technique.
S-phase cells in intact animals of the coelenterate species Eirene viridula, Hydractinia echinata, Hydra attenuata, and Hydra magnipapillata incorporate the thymidine analogue bromodeoxyuridine (BrdU) into newly synthesized DNA. BrdU-labelled nuclei divide and cells appear to undergo normal differentiation. Whole-mount preparations and macerated tissues were screened for S-phase cells by means of immunocytochemical detection of BrdU (Gratzner, 1982). It is demonstrated that spatial patterns of DNA replication can be evaluated easily. Cell lineages and pathways of cell migration could be traced.
Animals↗
Cell proliferation and early differentiation during embryonic development and metamorphosis of Hydractinia echinata.
The early embryonic development of Hydractinia lasts about 2.5 days until the developing planula larva acquires competence for metamorphosis. Most embryonic cells stop cycling on reaching the larval stage. In older larvae of Hydractinia, cells that are still proliferating occur exclusively in the endoderm in a typical distribution along the longitudinal axis. During metamorphosis, proliferation activity begins again. The number of S-phase cells has increased by the 9th hour after induction of metamorphosis. Proliferative activity starts in the middle gastric region and in basal parts of primary polyps. Tentacles and stolon tips are always free of replicating cells.
Animals↗
Endogenous low molecular weight factors, vitamin A and phorbol esters dramatically affect pattern formation and positional values in marine hydroids.
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Animals↗