@article{MeyerMorrisseySchartl1994,
  author    = {Meyer, Axel and Morrissey, Jean M. and Schartl, Manfred},
  title     = {Recurrent origin of a sexually selected trait in Xiphophorus fishes inferred from a molecular phylogeny},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61569},
  year      = {1994},
  abstract  = {DARWIN\(^1\) believed that sexual selection accounts for the evolution of exaggerated male ornaments, such as the sword-like caudal fin extensions of male fishes of the genus Xiphophorus, that appear detrimental to survival. Swordtails continue to feature prominently in empirical work and theories of sexual selection; the pre-existing bias hypothesis has been offered as an explanation for the evolution of swords in these fishes\(^{2,3}\). Based upon a largely morphological phylogeny, this hypothesis suggests that female preference to mate with sworded males arose in ancestrally swordless species, thus pre-dating the origin of the sword itself and directly driving its evolution. Here we present a molecular phylogeny (based on mitochondrial and nuclear DNA sequences) of Xiphophorus which differs from the traditional one: it indicates that the sword originated and was lost repeatedly. Our phylogeny suggests that the ancestor of the genus is more likely to have possessed a sword than not, thus questioning the applicability of the pre-existing bias hypothesis as an explanation for the cvolution of this sexually selected trait.},
  subject      = {Physiologische Chemie},
  language  = {en}
}
@article{MalitschekWittbrodtFischeretal.1994,
  author    = {Malitschek, Barbara and Wittbrodt, Joachim and Fischer, Petra and Lammers, Reiner and Ullrich, Axel and Schartl, Manfred},
  title     = {Autocrine stimulation of the Xmrk receptor tyrosine kinase in Xiphophorus melanoma cells and identification of a source for the physiological ligand},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61551},
  year      = {1994},
  abstract  = {The melanoma·inducing gene of Xiphophorus fish encodes the Xmrk receptor tyrosine kinase. U sing a highly specific antiserum p~oduced against the recombinant receptor expressed with a baculovirus, it is shown that Xmrk is the most abundant phosphotyrosine protein in fish melanoma and thus highly activated in the tumors. Studies on a melanoma cellline revealed that these cells produce an activity that considerably stimulates receptor autophosphorylation. The stimulating activity induces receptor down-regulation and can be depleted from the melanoma cellsupernatant by the immobilized recombinant receptor protein. The fish melanoma cells can thus be considered autocrine tumor cells providing a source for future purification and characterization of the Xmrk ligand.},
  subject      = {Physiologische Chemie},
  language  = {en}
}
@article{GoetzKoesterWinkleretal.1994,
  author    = {G{\"o}tz, Rudolf and K{\"o}ster, Reinhard and Winkler, Christoph and Raulf, Friedrich and Lottspeich, Friedrich and Schartl, Manfred and Thoenen, Hans},
  title     = {Neurotrophin-6 is a new member of the nerve growth factor family},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61544},
  year      = {1994},
  abstract  = {DURING vertebrale development, many neurons depend for survival and differentiation on their target cells\(^{1-3}\). The best documented mediator of such a retrograde trophic action is the neurotrophin nerve growth factor (NGF)\(^1\). NGF and the other known members of tbe neurotrophin family, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT -3) and neurotrophin-4/5 (NT -4/5) are conserved as distinct genes over large evolutionary distances\(^{4 -6}\). Here we report the cloning of neurotrophin-6 (NT -6), a new member of this family from the teleost fish Xiphophorus. NT -6 distinguishes itself from the other known neurotrophins in that it is not found as a soluble protein in the medium of producing cells. The addition of heparin (but not chondroitin) effects the release of NT -6 from cell surface and extracellular matrix molecules. Recombinant purified NT -6 has a spectrum of actions similar to NGF on chick sympathetic and sensory neurons, albeit with a lower potency. NT -6 is expressed in tbe embryonie valvulla cerebelli; expression persists in some adult tissues. The interaction of NT-6 with heparin-binding molecuJes may modulate its action in the nervous system .},
  subject      = {Physiologische Chemie},
  language  = {en}
}