We investigated whether metastatic phenotype is associated with a characteristic glycolipid pattern. For this study, we developed a system of variants with different metastatic potentials that we ...isolated from the highly metastatic T3 murine fibrosarcoma line by culture in 0.3% agar or on plastic. The glycolipid profiles of T3 cells and of their highly metastatic isolates were characterized by a high level of globotriaosylceramide (Gb3ose). On the other hand, Gb3ose was reduced in a weakly metastatic clone isolated from T3 cells. A reduced level of Gb3ose was also found in a weakly metastatic subclone isolated from a highly metastatic T3 clone. Propagation of this subclone led to the emergence of a series of variants which expressed a high metastatic potential together with a high Gb3ose level. We also observed that Gb3ose was 10 times more prevalent on the cell surface in T3 cells than in a weakly metastatic clone. On the whole, these findings indicate that, in our system of metastatic cells, a high Gb3ose level correlates with metastatic phenotype. It is possible that the highly exposed Gb3ose in metastatic cells is relevant to the metastatic process in view of the role played by the unique molecular structure of this glycolipid in other models of cell-to-cell interaction.
The extensive data available for He and Ne beam elastic scattering from Cu surfaces are analysed by full quantum mechanical calculations and by describing the atom-surface interaction potential ...according to the present knowledge on van der Waals pair-potentials. It is shown that Ne penetrates the surface electron cloud much deeper than He and that the ratio of Ne-to-He adsorption energies exceeds the ratio of the atomic polarizabilities.
We present the results of a helium diffraction study of the morphology of a Cu
3Au(001) surface at 140
K. Biatomic steps only are not able to describe the terrace morphology, and monoatomic steps ...must be included. The step height (1.855±0.015
Å) is closely comparable to the bulk interlayer spacing of Cu
3Au along the 〈001〉 direction (1.865
Å). Two kinds of terraces have been identified. The first class (A-terraces) are the majority. They are large terraces that display the well-known c(2×2) ordering of the Au–Cu termination. The second type (B-terraces) consists of much smaller terraces of uncertain composition. B-terraces are separated from A-terraces by a monoatomic step. Monoatomic steps are probably bunched into pairs.
We present the results of a helium diffraction study of the morphology of a Cu sub 3 Au(001) surface at 140 K. Biatomic steps only are not able to describe the terrace morphology, and monoatomic ...steps must be included. The step height (1.855 plus /minus 0.015 A) is closely comparable to the bulk interlayer spacing of Cu sub 3 Au along the < 001 > direction (1.865 A). Two kinds of terraces have been identified. The first class (A-terraces) are the majority. They are large terraces that display the well-known c(2x2) ordering of the Au-Cu termination. The second type (B-terraces) consists of much smaller terraces of uncertain composition. B-terraces are separated from A-terraces by a monoatomic step. Monoatomic steps are probably bunched into pairs.
X-ray specular reflectivity, in-plane grazing incidence X-ray diffraction (GIXRD) and photoelectron diffraction (PED) have been employed to study the Fe/Cu
3Au(001) system at the ALOISA beamline ...(Trieste Synchrotron, Italy). In-plane GIXRD has been used to determine the epitaxial strain of the film lattice by (H00) radial scans around the Cu
3Au(200) diffraction peak. PED has been employed in forward scattering conditions to determine the vertical spacing of the topmost layers and to look at atomic exchange processes. At very low coverage, Fe grows pseudomorphically on the fcc substrate; the bulk-like Fe bcc structure has been observed for an 18-Å thick Fe film. The PED analysis suggests that, at 1 ML Fe coverage, a full Au layer is segregated onto the surface with the Au atoms sitting in their fcc sites. A consistent fraction of a monolayer of Au is still present on top of the 18-Å Fe bcc film.
Lectins are suitable tools for investigating the glycoconjugate characteristics of metastatic cells. In the present study, we investigated whether there were differences between high metastatic T3 ...cells and a low metastatic isolate in their reactivities to several lectins specific for galactosyl and sialyl groups. Analysis of reactivity of the two cell lines to wheat germ agglutinin revealed a complex pattern. In fact, T3 cells had high-affinity, neuraminidase-resistant as well as low-affinity, neuraminidase-sensitive receptors. Instead, the low metastatic isolate showed only high-affinity receptors, both neuraminidase-resistant and neuraminidase-sensitive The two cell lines reacted similarly to galactose-specific lectins. These findings indicate that sialyl groups, rather than galactosyl groups, affect the metastatic behavior of our cell system.
X-ray specular reflectivity, in-plane grazing incidence X-ray diffraction (GIXRD) and photoelectron diffraction (PED) have been employed to study the Fe/Cu sub 3 Au(001) system at the ALOISA beamline ...(Trieste Synchrotron, Italy). In-plane GIXRD has been used to determine the epitaxial strain of the film lattice by (H00) radial scans around the Cu sub 3 Au(200) diffraction peak. PED has been employed in forward scattering conditions to determine the vertical spacing of the topmost layers and to look at atomic exchange processes. At very low coverage, Fe grows pseudomorphically on the fcc substrate; the bulk-like Fe bcc structure has been observed for an 18-A thick Fe film. The PED analysis suggests that, at 1 ML Fe coverage, a full Au layer is segregated onto the surface with the Au atoms sitting in their fcc sites. A consistent fraction of a monolayer of Au is still present on top of the 18-A Fe bcc film.
The extensive data available for He and Ne beam elastic scattering from Cu surfaces are analysed by full quantum mechanical calculations and by describing the atom-surface interaction potential ...according to the present knowledge on van der Waals pair-potentials. It is shown that Ne penetrates the surface electron cloud much deeper than He and that the ratio of Ne-to-He adsorption energies exceeds the ratio of the atomic polarizabilities.
