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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of morphogenetic mutants of hydra (1977)
    Springer
    Development genes and evolution 183 (1977), S. 193-206 
    Details
    ISSN: 1432-041X
    Keywords: Hydra mutant ; Morphogenetic substances ; Head formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A mutant ofHydra attenuata is analysed, theaberrant, which is distinct from the wild type in having a smaller head with fewer tentacles and only half the number of head-specific cells. The rate of head and foot regeneration and the doubling time are slower inaberrants than in normal hydra. The lower head-forming potential is paralleled by a reduced concentration of head-specific morphogens: compared to the wild type, in theaberrant the concentration of head activator is reduced to 70% in the head and to 50% in the body, the concentration of head inhibitor is reduced to 50% in the head and to 80% in the body. Theaberrant is more sensitive (3 times) to added head activator and less sensitive (〉5 times) to added head inhibitor than the wild type. The slower rate of foot regeneration is paralleled by a lower content of foot-specific morphogens: compared to the wild type, in theaberrant the foot activator is reduced to 40% and the foot inhibitor to 70%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867320
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of morphogenetic mutants of hydra (1977)
    Springer
    Development genes and evolution 183 (1977), S. 215-222 
    Details
    ISSN: 1432-041X
    Keywords: Hydra mutants ; Morphogenetic substances ; Size regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Minis have a doubling time of 2.4 days,maxis of 8 days.Minis regenerate head and foot 5 h faster thanmaxis.Minis have fewer tentacles (4.6) per head thanmaxis (6.1). Inmini the concentration of the head activator is equal to that inHydraattenuata, but the concentration of the head inhibitor is reduced (2-fold in the head, 1.2-fold in the body). The concentrations of the foot factors are normal.Minis respond likeHydra attenuata to head activator, foot activator and foot inhibitor, but they are less sensitive to head inhibitor Inmaxi the concentration of the head activator is higher than inmini (5-fold in the head, 10-fold in the body) and that of the head inhibitor is also higher (4-fold in the head, 5-fold in the body). The concentration of the foot inhibitor is normal, that of the foot activator is doubled.Maxis are insensitive to added head activator and less sensitive to added head inhibitor and foot inhibitor. Their response to foot activator is normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867322
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of morphogenetic mutants of hydra (1977)
    Springer
    Development genes and evolution 183 (1977), S. 207-214 
    Details
    ISSN: 1432-041X
    Keywords: Hydra mutant ; Morphogenetic substances ; Bud formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Non-budding mutants ofChlorohydra viridissima regenerate heads 6 h faster thanHydra attenuata and the number of tentacles per head is higher. The polarity in pieces from the gastric region is the more labile, the smaller the pieces are. In regenerates heads and tentacles form much more frequently than feet, giving rise to bipolar or multiheaded structures. Buds very seldom form under normal conditions, but they occasionally occur in regenerating animals with two cut surfaces. The higher head-forming potential in the mutant is paralleled by a higher head-activator concentration (20-fold in head, 4-fold in body), than inHydra attenuata, which is not accompanied by an equivalent increase in head-inhibitor concentration (1.4-fold in head, 2-fold in body). The foot-activator concentration is slightly reduced (1.3-fold), the foot-inhibitor concentration is higher (1.6-fold) than inH. attenuata. The mutant is extremely insensitive to head activator, relatively insensitive to head inhibitor and foot inhibitor, but sensitive to foot activator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867321
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  • 4
    Electronic Resource
    Electronic Resource
    Gastrin/CCK-like immunoreactivity in the nervous system of coelenterates (1980)
    Springer
    Histochemistry and cell biology 69 (1980), S. 61-68 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using immunocytochemistry, gastrin/CCK-like immunoreactivity is found in sensory nerve cells in the ectoderm of the mouth region of hydra and in nerve cells in the endoderm of all body regions of the sea anemone tealia. These results are corroborated by radioimmunoassay: One hydra contains at least 5 fmole and one tealia at least 2 nmole gastrin/CCK-like immunoreactivity. Reactivities towards gastrin and CCK antisera with different specificities suggest that the coelenterate gastrin/CCK-like peptide contains the C-terminal amino-acid sequence common to mammalian gastrin and CCK. In addition the radioimmunochemical data indicate that the coelenterate peptide also contains an amino-acid sequence that resembles the sequence 20–30 of porcine CCK-33, but that no other sequences of gastrin are present. Thus, it is probably more CCK-like than gastrin-like.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508367
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  • 5
    Electronic Resource
    Electronic Resource
    No junctional communication between epithelial cells in hydra (1980)
    [s.l.] : Nature Publishing Group
    Nature 288 (1980), S. 711-713 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Electrotonic coupling between epithelial cells was measured by conventional intracellular glass microelectrodes21. Current pulses were passed and voltages recorded through a single microelectrode. In the intact animal measurements were performed in the head, mid-gastric and foot regions with the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/288711a0
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  • 6
    Electronic Resource
    Electronic Resource
    A critical examination of the occurrence of FMRFamide immunoreactivity in the brain of guinea pig and rat (1984)
    Springer
    Histochemistry and cell biology 80 (1984), S. 63-71 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several reports (cf. Weber et al. (1981) Science 214: 1248–1251) have described the extensive occurrence, in rat brain, of material immunologically related to the molluscan neuropeptide FMRFamide. We have reexamined these data in guinea pig and rat, using six different antisera to FMRFamide. Immunoreactive perikarya and fibres were found to be distributed throughout the rodent brain (Table 1). This distribution was roughly similar to that found by Weber and coworkers. However, solid-phase absorption of the antisera with bovine pancreatic polypeptide, which shares an arginine and an amidated aromatic amino acid (RYamide) with FMRFamide, showed that staining in most regions could be due to crossreactivity with bovine pancreatic polypeptide-like (or neuropeptide Y-like) material. Double-labelling experiments with antisera to FMRFamide and bovine pancreatic polypeptide led to the same conclusion. The only structures where no apparent crossreactivity occurred were perikarya and fibres in the nucleus dorsomedialis, ventromedialis, periventricularis and paraventricularis hypothalami and fibres in the area lateralis hypothalami, nucleus parabrachialis, substantia grisea centralis mesencephali, various parts of the formatio reticularis, and spinal cord. Hence only these structures might contain material which is more related to the molluscan retrapeptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492773
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  • 7
    Electronic Resource
    Electronic Resource
    Bombesin-like immunoreactivity in the nervous system of hydra (1981)
    Springer
    Histochemistry and cell biology 73 (1981), S. 171-180 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With immunocytochemical methods, nerve cells have been detected in Hydra attenuata containing bombesin-like immunoreactivity. These nerve cells are located in the ectoderm of all body regions of the animal and are especially abundant in basal disk and tentacles. Radioimmunoassay of extracts of hydra demonstrated at least 0.2 pmol/g wet weight of bombesinlike immunoreactivity. The immunoreactive material elutes from Sephadex G-50 in a similar position to synthetic bombesin. The data show that bombesin-like peptides are among the phylogenetically oldest neuropeptides found so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493017
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  • 8
    Electronic Resource
    Electronic Resource
    FMRFamide-like immunoreactivity in the nervous system of hydra (1982)
    Springer
    Histochemistry and cell biology 73 (1982), S. 499-508 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary FMRFamide-like immunoreactivity has been localized in different parts of the hydra nervous system. Immunoreactivity occurs in nerve perikarya and processes in the ectoderm of the lower peduncle region near the basal disk, in the ectoderm of the hypostome and in the ectoderm of the tentacles. The immunoreactive nerve perikarya in the lower peduncle region form ganglion-like structures. Radioimmunoassays of extracts of hydra gave displacement curves parallel to standard FMRFamide and values of at least 8 pmol/gram wet weight of FMRFamide-like immunoreactivity. The immunoreactive material eluted from Sephadex G-50 in several components emerging shortly before or after position of authentic FMRFamide. The presence of FMRFamide-like material in coelenterates shows that this family of peptides is of great antiquity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493364
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  • 9
    Electronic Resource
    Electronic Resource
    Substance P-like immunoreactivity in the nervous system of hydra (1981)
    Springer
    Histochemistry and cell biology 71 (1981), S. 325-333 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using immunocytochemistry we find substance P-like material in nerve cells of hydra. These nerve cells are situated in the ectoderm of the basal disk and tentacles. Radioimmunoassay of hydra extracts gives dilution curves parallel to that of synthetic substance P, from which it can be calculated that one animal contains at least 0.6 fmol substance P-like immunoreactivity. After chromatography on Biogel P-100, the substance P-like immunoreactivity elutes as a peak in the void volume and a peak at the position of synthetic substance P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00495879
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  • 10
    Electronic Resource
    Electronic Resource
    Neurotensin-like immunoreactivity in the nervous system of hydra (1981)
    Springer
    Histochemistry and cell biology 72 (1981), S. 199-209 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurotensin-like immunoreactivity is found in nerve fibers present in all body regions of hydra. The nerve fibers are especially numerous in the ectoderm at the bases of the tentacles and in the ectoderm at a site just above the foot. Radioimmunoassays of acetic-acid extracts of hydra, using various region-specific antisera towards mammalian neurotensin, show the presence of multiple neurotensin-related peptides. The amounts of these peptides vary between 1 and 350 pmol per gram wet weight. Gel filtration on Sephadex G-25 reveals a fraction of neurotensin-like peptides that crossreacts equally well with an antiserum directed against sequence 1–8 and an antiserum directed against sequence 6–13 of neurotensin. This fraction elutes also at the position of neurotensin and might closely resemble the mammalian peptide. A fraction eluting with the void volume crossreacts preferentially with antisera directed against sequences 1–8 and 10–13 of neurotensin. Several components of apparent lower molecular weight than neurotensin crossreact preferentially with an antiserum against sequence 10–13. These last peptides represent the major portion of the neurotensin-like peptides in hydra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00517133
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