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Background. Although smaller variant forms of estrogen receptor (ER) messenger RNA (mRNA) have been detected in breast tumors, neither their prevalence nor their prognostic significance have been evaluated. Similarly, TRPM-2 mRNA, the product of a gene induced principally during the onset of apoptosis, is present in mouse and human breast cancer cell lines, but whether it also occurs in primary breast tumors and is related to disease outcome is unknown. Methods. The relative expression and transcript size of ER mRNA and TRPM-2 mRNA in 126 primary breast tumors were measured by Northern analysis and compared with tumor grade, hormone receptor status, extent of tumor necrosis, and survival. Results. In ER-positive tumors, 64% of the tumors had only the normal 6.5 kb ER mRNA, an additional 9% had the normal plus smaller ER mRNA, and 2% had variant forms. Only 8% of ER-negative tumors had ER mRNA transcripts. There were significant relationships between the occurrence of ER mRNA and low tumor grade, ER-positive receptor status, and better survival. In contrast, TRPM-2 mRNA was found in only 17% of breast tumors, none of which could be grouped with respect to grade, hormone receptor status, or survival. Conclusions. The presence of smaller variant forms of ER mRNA either alone or in association with the normal ER transcript is not indicative of an unfavorable prognosis, whereas TRPM-2 mRNA occurs in many primary breast tumors, but has no apparent relationship to survival.

Hybrids between distinct Xiphophorus species have been utilized for over 70 years to study melanoma and other neoplasms that can develop spontaneously in hybrid offspring. Genetic linkage mapping has proven to be important in delineating genomic areas that harbor oncogenes and tumor suppressors. Within this report, two parallel backcrosses have been utilized to generate a genetic linkage map for Xiphophorus fishes. Isozyme/allozyme, RFLP and PCR-based mapping techniques, including AP-PCR/RAPDs and microsatellite loci were utilized. The derived linkage map provides a total of 403 mapped polymorphisms distributed among 24 linkage groups, representative of 24 acro- and telocentric chromosome pairs. Genomic coverage is approximately one marker per 5.8 cM. Detailed genotypic analysis of the utilized hybrids revealed two areas of the genome that show significant segregation distortion. Loci within the linkage group harboring the sex determining locus (LG 24) and an autosomal linkage group (LG 21) show highly significant deviations from Mendelian expectations. This phenomenon is not present in a hybrid cross that utilizes a different backcross hybrid progenitor species. The derived map with sequence-tagged markers provides a framework for physical map generation, large-scale genomic sequencing and will further enable cross-genome comparisons of vertebrate genomes.

Whole mounts and cross-sections of embryos from three species of teleost fish were immunostained with the HNK-1 monoclonal antibody, which recognizes an epitope on migrating neural crest cells. A similar distribution and migration was found in all three species. The crest cells in the head express the HNK-1 epitope after they have segregated from the neural keel. The truncal neural crest cells begin to express the epitope while they still reside in the dorsal region of the neural keel; this has not been observed in other vertebrates. The cephalic and anterior truncal neural crest cells migrate under the ectoderm; the cephalic cells then enter into the gill arches and the anterior truncal cells into the mesentery of the digestive tract where they cease migration. These cephalic and anterior trunk pathways are similar to those described in Xenopus and chick. The neural crest cells of the trunk, after segregation, accumulate in the dorsal wedges between the somites, however, unlike in chick and rat, they do not migrate in the anterior halves of the somites but predominantly between the neural tube and the somites, the major pathway observed in carp and amphibians; some cells migrate over the somites. The HNK-1 staining of whole-mount embryos revealed a structure resembling the Rohon-Beard and extramedullary cells, the primary sensory system in amphibians. Such a system has not been described in fish.

We have studied neural crest development in two teleost fish species, Xiphophorus maculatus (platyfish) and X. heUeri (swordtail), and found similarities to that in other vertebrates but also some important differences. Unlike in other vertebrates, segregation of neural crest cells occurs in masses or groups from the dorsal-lateral part of the neural keel (tube) except in the mesencephalon region, where neural crest cells segregate from the dorsal-midline and in the most anterior trunk region, where they segregate individually. However, the cells were found in the usual neural tube-somite and somite-ectoderm migration pathways. Notably numerous cells, presumed in part to be neural crest cells, were found in a third location, dorsally on the neural tube. These cells exhibit a series of morphological stages referred to as ‘covering’, ‘condensation’, and ‘differentiation’. A great amount of ECM was observed in these fish and can be temporally and regionally correlated with the appearance of the neural crest cells. No major differences could be detected between the two fish species with the exception that segregation and appearance of neural crest cells in various locations occur earlier in the platyfish. This time difference could lead to perturbations in neural crest cell development in certain platyfish-swordtail hybrids and may contribute to the formation of neural-crest-derived pigment cell tumours, melanomas, in these hybrids.