TY  - JOUR
A1  - Riehl, R.
A1  - Schartl, Manfred
A1  - Kollinger, G.
T1  - Comparative studies on the ultrastructure of malignant melanoma in fish and human by freeze-etching and transmission electron microscopy
N2  - Malignant melanomas (MM) in the fish Xiphophorus and in humans were studied both by transmission electron microscopy (TEM) and freeze-etching (FE). In both fish and human melanomas the cells show interdigitations of the,plasma membranes. The nuclei are large and lobulated and have many nuclear pores. Melanosomes are abundant and melanosome complexes ("compound melanosomes") occur regularly. Pinocytotic vesicles could be demonstrated in fish and human melanomas showing iocal differences in frequency and distribution patterns in the tumor. lntercellular junctions are lacking in MM cells from fish and humans. The FE technique showed considerable advantages in demonstrating membrane-surface peculiarities such as nuclear pores or pinocytotic vesicles. The FE replicas of fish melanomas are like those of humans. These findings may support the hypothesis that melanoma in fish and humans reflect the same biological phenomenon.
KW  - Physiologische Chemie
KW  - Malignant melanoma
KW  - Fish
KW  - Human
KW  - Freeze-etching
KW  - Transmission electron microscopy
Y1  - 1984
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61920
ER  - 
TY  - JOUR
A1  - Götz, Rudolf
A1  - Raulf, Friedrich
A1  - Schartl, Manfrad
T1  - Brain-derived neurotrophic factor is more highly conserved in structure and function than nerve growth factor during vertebrate evolution
N2  - Mammalian nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are members of a protein family with perfectly conserved domains arranged around the cysteine residues thought to stabilize an invariant three-dimensional scaffold in addition to distinct sequence motifs that convey different neuronal functions. To study their structural and functional conservation during evolution, we have compared NGF and BDNF from a lower vertebrate, the teleost fi.sh Xiphophorus, with the mammalian homlogues. Genomic clones encoding fish NGF and BDNF were isolated by cross-hybridization using probes from the cloned mammalian factors. Fish NGF and BDNF were expressed by means of recombinant vaccinia viruses, purified, and their neuronal survival specificities for different classes of neurons were found to mirror those of the mammalian factors. The half-maximal survival concentration for chick sensory neurons was 60 pg/ml for both fish and mammalian purifi.ed recombinant BDNF. However, the activity ofrecombinant fish NGF on both chick sensory and sympathetic neurons was 6 ng,lml, 75-fold lower than that of mouse NGF. The different functional conservation of NGF and BDNF is also reflected in their structures. The DNA-deduced amino acid sequences of processed mature fish NGF and BDNF showed, compared to mouse, 63% and 90% identity, respectively, indicating that NGF bad reached an optimized structure later than BDNF. The retrograde extrapolation of these data indicates that NGF and BDNF evolved at strikingly different rates ftom a common ancestral gene about 600 million years ago. By RNA gel blot anaJysis NGF mRNA was detected during late embryonie development; BDNF was present in adult brain.
KW  - Physiologische Chemie
KW  - Brain-derived neurotrophic factor
KW  - Nerve growth factor
KW  - Fish
KW  - Recombinant protein expression
KW  - Neuronal survival
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61703
ER  -