A molecular genetic linkage map of mouse chromosome 18 reveals extensive linkage conservation with human chromosomes 5 and 18

An interspecific backcross between C57BL/6J and Mus spretus was used to generate a molecular genetic linkage map of mouse chromosome 18 that includes 23 molecular markers and spans approximately 86% of the estimated length of the chromosome. The Apc, Camk2a, D18Fcr1, D18Fcr2, D18Leh1, D18Leh2, Dcc, Emb-rs3, Fgfa, Fim-2/Csfmr, Gnal, Grl-1, Grp, Hk-1rs1, Ii, Kns, Lmnb, Mbp, Mcc, Mtv-38, Palb, Pdgfrb, and Tpl-2 genes were mapped relative to each other in one interspecific backcross. A second interspecific backcross and a centromere-specific DNA satellite probe were used to determine the distance of the most proximal chromosome 18 marker to the centromere. The interspecific map extends the known regions of linkage homology between mouse chromosome 18 and human chromosomes 5 and 18 and identifies a new homology segment with human chromosome 10p. It also provides molecular access to many regions of mouse chromosome 18 for the first time.     

Calling song and selective phonotaxis in the field crickets,Gryllus firmus andG. pennsylvanicus (Orthoptera: Gryllidae)

The field cricket species, Gryllus firmusand G. pennsylvanicus,occur in a mosaic hybrid zone that roughly parallels the eastern slope of the Appalachian mountains in the northeastern United States. It is important to know what role, if any, the calling song plays in mate choice in sympatric and allopatric populations. In this report, we present results on the variability of calling song properties along transects across this hybrid zone. We also present the results of experiments on phonotactic selectivity of females from an allopatric population of G. firmus.The male calling song of allopatric G. firmuswas significantly slower in temporal rhythm (i. e., chirp and pulse repetition rates) and lower in pitch (i.e., dominant frequency) than that of allopatric G. pennsylvanicus.Calling song properties of males recorded in the hybrid zone varied considerably in temporal and spectral properties. In two-stimulus (choice) phonotaxis experiments, allopatric females of G. firmuspreferred synthetic calling songs with conspecific pulse repetition rates over songs that had lower and higher pulse rates. This preference persisted even when the sound pressure levels of alternative stimuli were unequal. Therefore, allopatric females of G. firmuscan discriminate between conspecific and heterospecific calling songs. Whether or not this same selectivity is present in sympatric populations remains unclear. Investigations of phonotactic selectivity in other allopatric and sympatric populations of both species are currently under way.     

Valinomycin-induced modulation of adriamycin resistance and cationic probe distribution in MCF-7 cell lines.

In vitro restoration of adriamycin sensitivity in a resistant human breast tumor cell line was obtained by continuous exposure to nanomolar nontoxic valinomycin concentrations. Seven-day treatment with nanomolar valinomycin concentrations caused a slight increase of the signal of the cationic fluorescent cyanine probe DiOC5(3) but did not appreciably affect adriamycin incorporation in the cells. A marked increase of the DiOC5(3) signal was obtained in the presence of micromolar valinomycin concentrations, which were incompatible with the in vitro cellular growth.     

Mouse Chromosome 13

Chair of Committee for Mouse Chromosome 13     

Cobalt blocks the decrease in MEPSP frequency on depolarization in calcium-free hypertonic media

Media made hyperosmotic with sucrose increase the frequency of spontaneously released quanta of transmitter, or miniature excitatory postsynaptic potentials (MEPSPs). In calcium-free medium, depolarization with high potassium reduces the MEPSP frequency, presumably due to calcium efflux in the reversed gradient condition. This effect of depolarization is blocked by cobalt, supporting the above interpretation of the effects of hypertonicity and depolarization and suggesting that cobalt can block efflux as well as influx through calcium channels.     

Solvation properties of ubiquinone-10 in solvents of different polarity

The solvation properties of ubiquinone-10 and ubiquinol-10 in a wide variety of solvents of polarity varying from alkanes to water are reported. Greatest solubility is observed in solvents of intermediate polarity and particularly where low polarity is combined with a pronounced tendency to interact with the benzoquinone substituent of the ubiquinone molecule. This includes solvents like chloroform and benzene. Ubiquinone-10 is somewhat less polar than ubiquinol-10 as judged by comparative solubilities of the two molecules. Proton-NMR chemical shift measurements and aggregation studies in selected solvents indicate that in ubiquinone-10 in the liquid phase and in solution in hydrocarbons like dodecane the molecules have a preferred association possibly involving stacking of the benzoquinone rings. Surface balance studies indicated that the surface-active character of ubiquinone-10 is relatively weak and only in a comparatively polar and highly structured solvent, formamide, was there evidence of an effect on surface tension of the solvent. The critical micelle concentratiom in this solvent was estimated to be about 5 M on the basis of surface tension measurements. Ubiquinone-10 is well known to form virtually insoluble monolayers at the air/water interface. Studies of the partition of ubiquinone-10 in binary mixtures of solvents suggest that the interaction of the benzoquinone ring substituent with structured polar solvents is considerably weaker than the internal cohesion between molecules of the solvent. No evidence on the basis of wide-angle X-ray diffraction measurements was obtained to indicate that solvent molecules were a component of the crystal lattice of ubiquinone-10 that had precipitated from solvent mixtures.     

Expression by human fetal organs of organ-specific cancer neoantigens as measured by leukocyte adherence inhibition

Summary Human cancers express organ-specific cancer neoantigens (OSN) as determined by in vitro leukocyte responses to extracts of cancers by the tumor host. In this study, we determined whether the OSNs were normal developmental proteins that were expressed by fetal organs and re-expressed with oncogenesis. Fetal extracts, principally of lung and colon but also of liver and kidney, were tested for their ability to induce leukocyte adherence inhibition (LAI) as compared to extracts from adult tissues of the same organ. Leukocytes from lung cancer patients showed positive LAI responses to 13- and 19-week fetal lung tissue. Likewise, leukocytes from colon cancer patients showed positive LAI responses to 14- and 19-week fetal colon tissue, whereas leukocytes from control subjects did not. Neither group responded positively to 21-week fetal organs. Criss-cross experiments showed that the fetal antigen was organ specific. Multiparous pregnant women showed positive LAI responses to cancer extracts but not to extracts from normal tissues of the same organ. The pattern of the LAI response was bell-shaped. Positive LAI responses to lung and breast cancer were detected at 4 to 7 months gestation and peaked at 5 months. To the fetal colon, LAI positive responses were detected at 5 to 8 months gestation, with the peak response at 6 months. The results indicate that OSN of cancers are also expressed by fetal organs and sufficient antigen is shed by fetal organs to sensitize pregnant women. Older fetal organs (21 weeks) and adult organs do not express an immunogenic or antigenic OSN.Supported by a grant from the National Cancer Institute of Canada     

High sensitivity method for fluorofore detection in gradient polyacrylamide slab gels through excitation by laser light: application to glycoproteins stained with concanavalin A-fluorescein isothiocyanate

An easy-to-assemble apparatus for the laser-light excitation of fluorofores in polyacrylamide gels is described. The assemblage is made up of a continuous-wave ion-argon laser with adjustable power output, a beam diffuser, appropriate filters to block excitation light, and a photographic camera. With this setup a minimum 20-fold increase of sensitivity was obtained for fluorofore detection in polyacrylamide gels as compared to the more conventional uv-light excitation using a commercial preparation of Con A-FITC (concanavalin A-fluorescein isothiocyanate) as reference molecule in the gel. The same apparatus, used to analyze the Con A-positive glycoproteins contained in serum Cohn fraction IV separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed a number of fluorescent components in a wide range of relative intensities while uv-light excitation showed none. Acrylamide concentration in the gel is critical, since a working limit of between 10 and 12% has been found, above which the diffusion of Con A-FITC in the gel, necessary to label glycoprotein bands, is hampered. The system described here also permits the optimization of detection of minor components not otherwise observable by conventional light excitation, because light power, angle of incidence, and beam divergence can be adapted to analyze specific areas of the sample gel.