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1.
M B Faletto A E Maccubbin P L Koser J A Vangalio H L Gurtoo 《Cancer biochemistry biophysics》1989,10(3):197-205
C3H/10T1/2 clone 8 (10T1/2) cells possess aryl hydrocarbon hydroxylase (AHH) activity capable of metabolizing polycyclic aromatic hydrocarbons to ultimate carcinogenic forms. AHH activity in 10T1/2 cells was measured before and after culturing in the presence of benzo[a]pyrene (B[a]P), and compared to the AHH activity found in carcinogen-transformed 10T1/2 cell lines treated similarly. The cell lines were also examined for B[a]P-DNA adduct formation, using the 32P-postlabelling technique. Treatment of parental 10T1/2 cells with B[a]P was found to significantly increase AHH activity and produce substantial numbers of DNA adducts. In addition to a major B[a]P-DNA adduct, 5-6 minor DNA adducts were also detected. Relative to parental 10T1/2 cells, an aflatoxin B1-transformed 10T1/2 cell line (7SA) was found to have significantly depressed AHH activity. In addition, after treatment with B[a]P, 7SA cells had only 8% of the B[a]P-DNA adduct levels found in 10T1/2 cells. This system may provide an in vitro model for investigating mechanisms responsible for the depression of cytochrome P-450 activities by chemical carcinogens. 相似文献
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Genetic variation at the Major Histocompatibility Complex locus DQ beta was
analyzed in 233 beluga whales (Delphinapterus leucas) from seven
populations: St. Lawrence Estuary, eastern Beaufort Sea, eastern Chukchi
Sea, western Hudson Bay, eastern Hudson Bay, southeastern Baffin Island,
and High Arctic and in 12 narwhals (Monodon monoceros) sympatric with the
High Arctic beluga population. Variation was assessed by amplification of
the exon coding for the peptide binding region via the polymerase chain
reaction, followed by either cloning and DNA sequencing or single-stranded
conformation polymorphism analysis. Five alleles were found across the
beluga populations and one in the narwhal. Pairwise comparisons of these
alleles showed a 5:1 ratio of nonsynonymous to synonymous substitutions per
site leading to eight amino acid differences, five of which were
nonconservative substitutions, centered around positions previously shown
to be important for peptide binding. Although the amount of allelic
variation is low when compared with terrestrial mammals, the nature of the
substitutions in the peptide binding sites indicates an important role for
the DQ beta locus in the cellular immune response of beluga whales.
Comparisons of allele frequencies among populations show the High Arctic
population to be different (P < or = .005) from the other beluga
populations surveyed. In these other populations an allele, Dele-DQ
beta*0101-2, was found in 98% of the animals, while in the High Arctic it
was found in only 52% of the animals. Two other alleles were found at high
frequencies in the High Arctic population, one being very similar to the
single allele found in narwhal.
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David?E. Koser Emad Moeendarbary Janina Hanne Stefanie Kuerten Kristian Franze 《Biophysical journal》2015,108(9):2137-2147
Mechanical signaling plays an important role in cell physiology and pathology. Many cell types, including neurons and glial cells, respond to the mechanical properties of their environment. Yet, for spinal cord tissue, data on tissue stiffness are sparse. To investigate the regional and direction-dependent mechanical properties of spinal cord tissue at a spatial resolution relevant to individual cells, we conducted atomic force microscopy (AFM) indentation and tensile measurements on acutely isolated mouse spinal cord tissue sectioned along the three major anatomical planes, and correlated local mechanical properties with the underlying cellular structures. Stiffness maps revealed that gray matter is significantly stiffer than white matter irrespective of directionality (transverse, coronal, and sagittal planes) and force direction (compression or tension) (Kg= ∼130 Pa vs. Kw= ∼70 Pa); both matters stiffened with increasing strain. When all data were pooled for each plane, gray matter behaved like an isotropic material under compression; however, subregions of the gray matter were rather heterogeneous and anisotropic. For example, in sagittal sections the dorsal horn was significantly stiffer than the ventral horn. In contrast, white matter behaved transversely isotropic, with the elastic stiffness along the craniocaudal (i.e., longitudinal) axis being lower than perpendicular to it. The stiffness distributions we found under compression strongly correlated with the orientation of axons, the areas of cell nuclei, and cellular in plane proximity. Based on these morphological parameters, we developed a phenomenological model to estimate local mechanical properties of central nervous system (CNS) tissue. Our study may thus ultimately help predicting local tissue stiffness, and hence cell behavior in response to mechanical signaling under physiological and pathological conditions, purely based on histological data. 相似文献
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