TY - JOUR A1 - Meyer, Manfred K. A1 - Schartl, Manfred T1 - Eine neue Xiphophorus-Art aus Vera Cruz, Mexiko : (Pisces: Poeciliidae) N2 - Xiphophorus andersi n. sp. from the Rio Atoyac, Vera Cruz, Mexico is described: lang head, moderately slender body, large dark black spar at the basis of the anal fin; adult male with short sword-like caudal appendage; rip of ray 5a of gonopodium without a developed claw. Xiphophorus andersi n. sp. differs by the combination of distinct characters from all the other species of the genus known so far. The new species shows features of both the so-called platyfish species group and the so-called swordtail species group. KW - Schwertkärpfling KW - Veracruz Y1 - 1979 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87124 ER - TY - CHAP A1 - Anders, F. A1 - Scholl, E. A1 - Schartl, Manfred T1 - Xiphophorus als Modell in der Krebsforschung N2 - No abstract available. KW - Schwertkärpfling KW - Krebsforschung KW - Modell Y1 - 1979 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-72752 ER - TY - CHAP A1 - Schartl, A. A1 - Schartl, Manfred A1 - Anders, F. T1 - Phenotypic conversion of malignant melanoma to benign melanoma and vice versa in Xiphophorus N2 - No abstract available. KW - Schwertkärpfling KW - Krebs Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86662 ER - TY - CHAP A1 - Anders, F. A1 - Scholl, E. A1 - Schartl, Manfred T1 - Environmental and hereditary factors in the causation of neoplasia, based on studies of the Xiphophorus fish melanoma system N2 - Neoplasia in Xiphophorus can be classified into: a) a Jarge group triggered by carcinogens; b) a large group triggered by promoters; and c) a small group that develops "spontaneously" according to Mendelian Jaw. The process leading to susceptibility for neoplasia is represented by the disintegration of gene systems that normally protect the fish from neoplasia. Interpopulational arid interracial hybridization is the most effective process that Ieads to disintegration of the protective gene systems. Environmental factors may complete disintegration in somatic cells and thus may trigger neoplasia. The applications of the findings on Xiphophorus to humans are discussed. KW - Schwertkärpfling KW - Gen KW - Umweltfaktor KW - Tumor Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86402 ER - TY - CHAP A1 - Anders, F. A1 - Schartl, Manfred A1 - Scholl, E. T1 - Evaluation of environmental and hereditary factors in carcinogenesis, based on studies in Xiphophorus N2 - Neoplasia in Xiphophorus can be classified into a) a large group that is triggered by carcinogens; b) a large group triggered by promoters; c) a small group that develops "spontaneously" following interpopulational and interracial hybridizations; and d) a small group that develops "spontaneously" following germ line mutation. The process leading to susceptibility for neoplasia is represented by the disintegration of gene systems that normally protect the fish from neoplasia. Hybridization is the most effective process that leads to disintegration of the protection gene systems. Environmental factors may complete disintegration and thus may trigger neoplasia. It is discussed whether the findings on Xiphophorus may also apply to humans. KW - Schwertkärpfling KW - Gen KW - Umweltfaktor KW - Carcinogenese Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-72741 ER - TY - JOUR A1 - Schartl, A. A1 - Schartl, Manfred A1 - Anders, F. T1 - Promotion and regression of neoplasia by testosterone-promoted cell differentiation in Xiphophorus and Girardinus N2 - No abstract available. KW - Schwertkärpfling KW - Lebendgebärende Zahnkarpfen Y1 - 1982 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86684 ER - TY - CHAP A1 - Anders, Fritz A1 - Schartl, Manfred A1 - Barnekow, Angelika T1 - Xiphophorus as an in vivo model for studies on oncogenes N2 - The capacity of Xiphophorus to develop neoplasia can be formally assigned to a "tumor gene" (Tu), which appears to be a normal part of the genome of all individuals. The wild fish have evolved population-specific and cell type-specific systems of regulatory genes (R) for Tu that protect the fish from neoplasia. Hybridization of members of different wild populations in the laborstory followed by treatment of the hybrids with carcinogens led to disintegration of the R systems permitting excessive expression of Tu and thus resulting in neoplasia. Certain hybrids developed neoplasia even spontaneously. Observations on the genuine phenotypic effect of the derepressed Tu in the early embryo indicated an essential normal function of this oncogene in cell differentiation, proliferation and cell-cell communication. Tu appeared to be indispensable in the genome but may also be present in accessory copics. Recently, c-src, the cellular homolog of the Rous sarcoma virus oncogene v-src, was detected in Xiphophorus. The protein product of c-src, pp60c-src, was identified and then examined by its associated kinase activity. This pp60c-src was found in all individuals tested, but, depending on the genotype, its kinase activity was different. The genetic characters of c-src, such as linkage relations, dosage relations, expression, etc., correspond to those of Tu. From a systematic study which showed that pp60c-src was present in all metazoa tested ranging from mammals down to sponges, we concluded that c-src has evolved with the multicellular organization of animals. Neoplasia of animals and humans is a characteristic closely related to this evolution. Our data showed that small aquariurn fish, besides being used successfully because they are time-, space-, and money-saving systems for carcinogenicity testing, are also highly suitable for basic studies on neoplasia at the populational, morphological, developmental, cell biological, and molecular levels. KW - Schwertkärpfling KW - In vivo KW - Onkogen Y1 - 1984 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86398 ER - TY - CHAP A1 - Riehl, Rüdiger A1 - Schartl, Manfred A1 - Anders, Fritz T1 - An ultrastructural study of melanoma in Xiphophorus N2 - Melanotic melanoma (MM) of Xiphophorus (Teleostei: Poeciliidae) was studied by conventional preparations and freeze-etch preparations for electron microscopy. MM of Xiphophorus exhibits tightly packed pigment cells with prominent dendritic processes and interdigitations of their plasma membranes. The most impressive feature of MM cells is the occurrence of Iarge lobulated nuclei with numerous nuclear pores and some nuclear pockets. Abundant spheroidal or ellipsoidal melanosomes (diameter 200-650 nm) and vesicular structures are distributed throughout the cellular dendrites, whereas the perinucJear cytoplasm is free of melanosomes. A further characteristic feature of melanoma cells in fish is the occurrence of melanosome complexes (i.e., "compound melanosomes"). These melanosome complexes consist of a few to numerous melanosomes, which are enveloped by a separate rnembrane. Pinocytotic vesicles couJd be demonstrated with distinct differences in frequency and distribution patterns, indicating differences in the metabolic activities of the cells in the same melanoma. Intercellular junctions are lacking in the MM cells. The conventional TEM technique showed clear advantages in the demonstration of intemal architecture of organelles, whereas FE bad considerable potential in respect to the visualization of membrane surface specializations. KW - Schwertkärpfling KW - Krebs KW - Ultrastruktur Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-70978 ER - TY - CHAP A1 - Peter, R. U. A1 - Schartl, Manfred A1 - Anders, F. A1 - Duncker, H.-R. T1 - Pigment pattern formation during embryogenesis in Xiphophorus N2 - No abstract available. KW - Schwertkärpfling KW - Embryonalentwicklung KW - Pigmentmuster Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69370 ER - TY - JOUR A1 - Mäueler, Winfried A1 - Raulf, Friedrich A1 - Schartl, Manfred T1 - Expression of proto-oncogenes in embryonic, adult, and transformed tissue of Xiphophorus (Teleostei: Poeciliidae) N2 - In Xiphophorus the causative, primary cellular oncogene for melanoma formation has been assigned by classical genetics to a sex-chromosomal locus, designated Tu. Activation of Tu was proposed to be the result of the elimination of Tu-specific regulatory genes which normally suppress the transforming function in the nontumorous state. In order to understand the role which known proto-oncogenes migbt play in this process, we have analysed the expression of src, erb A, erb B, ras, abl, sis and mil related genes from Xiphophorus during embryogenesis, in non-tumorous organs and in melanoma cells. For src, ras, erb B and sis a differential expression during embryogenesis and/or in normal organs was detected, with preferential expression of src in neural tissues, a high abundance of sis transcripts in an embryonal epitheloid cellline and of erbB transcripts in the head nephros. In melanoma cells ras, src and a v-erb B related gene were found to be expressed. The src gene most likely is more involved in secondary processes during tumor progression, while the expression of the v-erb B related gene might be transformation-specific because recently such a sequence was found to map to the close vicinity of the Tu-locus. KW - Schwertkärpfling KW - Protoonkogen KW - Gewebe Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86233 ER -