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WALTER C. QUEVEDO JACOB DYCKMAN RUTH HALABAN GISELA E. MOELLMANN JANET M. COWAN THOMAS J. HOLSTEIN 《Pigment cell & melanoma research》1988,1(Z1):124-131
The BULT melanoma originated at Brown University as a spontaneous, small black nodule on the tail of an adult female mouse of the LT/Ch strain. Histological examination of a portion of the tumor indicated that it was intradermal and consisted predominantly of heavily melanized, ovoid to fusiform cells with melanin-laden macrophages scattered among them. The BULT melanoma has been maintained in LT/Ch mice for approximately 5 years by periodic transplantation, at first subcutaneously on the flanks and, more recently, intramuscularly in the hind legs. The shift in transplantation site was made following a marked decline in the growth of subcutaneous grafts. The transplants have retained the uniform deep-black melanization and general histology of the primary melanoma. Numerous melanosomes at all stages of development are found within the melanoma cells. DOPA-positive cytoplasmic vesicles are abundant. Occasional autophagic vacuoles containing clusters of melanosomes are also present. A few metastases from the transplanted melanoma have been observed in lymph nodes and on one occasion in the lungs. When grown in vitro, BULT melanoma cells do not require special growth promoting agents (e.g., TPA; cAMP) in order to proliferate. The BULT melanoma differs in one or more respects from each of the other three transplantable spontaneous mouse melanomas widely used in cancer research. In addition, it arose in a strain of mice characterized by the spontaneous death of melanocytes while the latter are engaged in synthesizing eumelanin within hair follicles. Karyotypic analysis of cultured cells showed a modal chromosome number of 68 with a range of 58–72 chromosomes. 相似文献
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The Control of Color in Mammals 总被引:1,自引:0,他引:1
SYNOPSIS. Recent advances in the biology of mammalian pigmentationare reviewed.Particular attention is given to emerging informationon the integration of pigmentary events occurring at differentlevels of biological organization within mammalian skin andhair. The structural and functional significance of keratinocytesand melanocytes as components of mammalian epidermal melaninunits is viewed from this perspective. New evidence on the natureof genetic, developmental, endocrine, and radiation influenceson performance of melanocytes and the establishment of pigmentarypatterns is summarized. 相似文献
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Models for the spatial distribution of protein, lipid and water in gap junction structures have been constructed from the results of the analysis of X-ray diffraction data described here and the electron microscope and chemical data presented in the preceding paper (Caspar, D. L. D., D. A. Goodenough, L. Makowski, and W.C. Phillips. 1977. 74:605-628). The continuous intensity distribution on the meridian of the X-ray diffraction pattern was measured, and corrected for the effects of the partially ordered stacking and partial orientation of the junctions in the X-ray specimens. The electron density distribution in the direction perpendicular to the plane of the junction was calculated from the meridional intensity data. Determination of the interference function for the stacking of the junctions improved the accuracy of the electron density profile. The pair-correlation function, which provides information about the packing of junctions in the specimen, was calculated from the interference function. The intensities of the hexagonal lattice reflections on the equator of the X-ray pattern were used in coordination with the electron microscope data to calculate to the two-dimensional electron density projection onto the plane of the membrane. Differences in the structure of the connexons as seen in the meridional profile and equatorial projections were shown to be correlated to changes in lattice constant. The parts of the junction structure which are variable have been distinguished from the invariant parts by comparison of the X-ray data from different specimens. The combination of these results with electron microscope and chemical data provides low resolution three- dimensional representations of the structures of gap junctions. 相似文献
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The role of nitric oxide in cancer 总被引:4,自引:0,他引:4
WEIMING XU Li ZHI LIU MARILENA LOIZIDOU MOHAMED AHMED IAN G CHARLES Wolfson Institute for Biomedical Research Cruciform Building Gower Street UCL London WC E AUUK Department of Surgery Charles Bell House - Riding House Street UCL London WW EJ UK 《Cell research》2002,(Z2)
Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including va-sodilatation, neurotransmission and macrophage-mediated immunity. The family of nitric oxide synthases (NOS) comprises inducible NOS (iNOS), endothelial NOS (eNOS), and neuronal NOS (nNOS). Interestingly, various studies have shown that all three isoforms can be involved in promoting or inhibiting the etiology of cancer. NOS activity has been detected in tumour cells of various histogenetic origins and has been associated with tumour grade, proliferation rate and expression of important signaling components associated with cancer development such as the oestrogen receptor. It appears that high levels of NOS expression (for example, generated by activated macrophages) may be cytostatic or cytotoxic for tumor cells, whereas low level activity can have the opposite effect and promote tumour growth. Paradoxically therefore, NO (and related reactive nitrogen species) may have both genotoxic and angiogenic pro 相似文献
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Paired sequence difference in ribosomal RNAs: evolutionary and phylogenetic implications 总被引:12,自引:1,他引:11
Ribosomal RNAs have secondary structures that are maintained by internal
Watson-Crick pairing. Through analysis of chordate, arthropod, and plant 5S
ribosomal RNA sequences, we show that Darwinian selection operates on these
nucleotide sequences to maintain functionally important secondary
structure. Insect phylogenies based on nucleotide positions involved in
pairing and the production of secondary structure are incongruent with
those constructed on the basis of positions that are not. Furthermore,
phylogeny reconstruction using these nonpairing bases is concordant with
other, morphological data.
相似文献
8.
Mitochondrial gene order is not conserved in arthropods: prostriate and metastriate tick mitochondrial genomes 总被引:25,自引:15,他引:10
The entire mitochondrial genome was sequenced in a prostriate tick, Ixodes
hexagonus, and a metastriate tick, Rhipicephalus sanguineus. Both genomes
encode 22 tRNAs, 13 proteins, and two ribosomal RNAs. Prostriate ticks are
basal members of Ixodidae and have the same gene order as Limulus
polyphemus. In contrast, in R. sanguineus, a block of genes encoding NADH
dehydrogenase subunit 1 (ND1), tRNA(Leu)(UUR), tRNA(Leu)(CUN), 16S rDNA,
tRNA(Val), 12S rDNA, the control region, and the tRNA(Ile) and tRNA(Gln)
have translocated to a position between the tRNA(Glu) and tRNA(Phe) genes.
The tRNA(Cys) gene has translocated between the control region and the
tRNA(Met) gene, and the tRNA(Leu)(CUN) gene has translocated between the
tRNA(Ser)(UCN) gene and the control region. Furthermore, the control region
is duplicated, and both copies undergo concerted evolution. Primers that
flank these rearrangements confirm that this gene order is conserved in all
metastriate ticks examined. Correspondence analysis of amino acid and codon
use in the two ticks and in nine other arthropod mitochondrial genomes
indicate a strong bias in R. sanguineus towards amino acids encoded by
AT-rich codons.
相似文献
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