TY  - JOUR
A1  - Schartl, Manfred
A1  - Wittbrodt, J.
A1  - Mäueler, W.
A1  - Raulf, F.
A1  - Adam, D.
A1  - Hannig, G.
A1  - Telling, A.
A1  - Storch, F.
A1  - Andexinger, S.
A1  - Robertson, S. M.
T1  - Oncogenes and melanoma formation in Xiphoporus (Teleostei: Poeciliidae)
N2  - In Xiphophorus melanoma formation has been attributed by classical genetic findings to the overexpression of a cellular oncogene (Tu) due to elimination of the corresponding regulatory gene locus in hybrids. We have attempted to elucidate this phenomenon on the molecular biological level. Studies on the structure and expression of known proto-oncogenes revealed that several of these genes, especially the c-src gene of Xiphophorus, may act as effectors in establishing the neoplastic phenotype of the melanoma cells . However, these genes appear more to participate in secondary steps of tumorigenesis. Another gene, being termed Xmrk, which represents obviously a so far unknown proto-oncogene but with a cons iderably high similarity to the epidermal growth-factorreceptor gene, was mapped to the Tu-containing region of the chromosome. This gene shows features with respect to its structure and expression that seem to justify it to be regarded as a candidate for a gene involved in the primary processes leading to neoplastic transformation of pigment cells in Xiphophorus.
KW  - Schwertkärpfling
KW  - Onkogen
KW  - Melanom
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87149
ER  - 
TY  - JOUR
A1  - Raulf, F.
A1  - Robertson, S. M.
A1  - Schartl, Manfred
T1  - Evolution of the neuron-specific alternative splicing product of the c-src proto-oncogene
N2  - The observation of a slower migrating form of pp6oc-src in neural tissue of chicken and mouse has recently been shown to be due to an alternative transcript form of tbe c-src gene (Martinez et al.: Science 237:411-415, 1987; Levy et al.: Mol Cell Bio17:4142- 4145, 1987). An insertion of 18 basepairs between exons 3 and 4, presumed to be due to alternative splicing of a mini-exon, gives rise to six amino acid residues not found in the non-neuronal (termed flbroblastic) form of pp60\(^{c-src}\). Wehave addressed the question of the evolutionary origin of the c-src neuronal insert · and its functional signiflcance regarding neural-speciflc expression of the c-src gene. To this end we have investigated whether the c-src gene of a lower verlebrate (the teleost fish Xiphophorus) gives rise to a neural-specific transcript in an analogous manner. We could show that the fish c-src gene does encode for a "fibroblastic" and a "neuronal" form of transcript and that the neuronal transcript does indeed arise by way of alternative splicing of a mini-exon. The miniexon is also 18 basepairs long and we could demoostrate directly that this exon lies within the intron separating exons 3 and 4. For comparative purposes we have examined whether the fish c-yes gene, the member of the src gene family most closely related to c-src, also encodes a neural tissue-specific transcript. No evidence for a second transcript form in brain was obtained. This result suggests that the mini-exon arose within the c-src gene lineage sometime between the srclyes gene duplication event and the divergence of the evolutionary lineage giving rise to the teleost fish. Published genomic sequence of src-related genes in Drosophila and our own results with Hydra demoostrate no intron in these species at the analogous location, consistent with first appearance of this mini-exon sometime between 550 and 400 million years ago.
KW  - Physiologische Chemie
KW  - Xiphophorus
KW  - teleost flsh
KW  - polymerase
KW  - chain reaction
KW  - RT -PCR
KW  - mini-exon
KW  - pp6oc-src
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61796
ER  -