11.
LITERATURE
CITED
353
11.5. Microscopy of Negatively Stained Material
Valentine and Home (1962) point out that one should not use a small
objective aperture (or an unusually long objective focal length) in working with negatively stained material. To do so minimizes contrast differences between the dense background material and the specimen, rather
than exaggerating it, as is the case when the background density is
minimal.
If one wants maximal contrast from negatively stained material, one
should also operate the microscope at the lowest practical accelerating
voltage. Below 60 kv the contrast of all material rises nearly in inverse
proportion to the high tension. For the future it would seem that the
development of a truly low voltage electron microscope would offer the
best possibility of visualizing small, light molecules negatively stained.
Thus, if one accepts a contrast limit of about 20-30 A based on an
accelerating voltage of 60 kv, a voltage reduction to 15 kv should increase
the contrast nearly four times. This would be expected to give a limit of
visibility to negatively stained material of 5-8 A.
LITERATURE CITED
Brenner, S., and Home, R. W. (1959). Biochim.
Biophys.
Acta 34, 103.
Farrant, J. L. (1954). Biochim.
Biophys.
Acta 13, 569.
Hall, C. E. (1955). /. Biophys.
Biochem.
Cytol. 1, 1.
Huxley, H. E. (1956). In "Electron Microscopy," Proc. Stockholm Conf., p. 260. Almqvist
& Wiksell, Stockholm.
Huxley, H. E. (1962). In "Electron Microscopy" (Proc. 5th Intern. Congr.), Vol. 2, p. O-l.
Academic Press, New York.
Huxley, H. E., and Zubay, G. (1960). Proc. European
Regional
Conf. Electron
Microscopy,
Delft, 2, 703. De Nederlandse Vereniging voor E. M., Delft.
Home, R. W., and Brenner, S. (1960). 4th Intern.
Conf. Electron
Microscopy,
Berlin,
1958, 2, 265. Springer, Berlin.
Valentine, R. C. (1959). Nature
184, 1838.
Valentine, R. C. (1960). Proc. European
Regional
Conf. Electron
Microscopy,
Delft,
2,
708. De Nederlandse Vereniging voor E. M., Delft.
Valentine, R. C., and Home, R. W. (1962). In "The Interpretation of Ultrastructure"
(R. J. C. Harris, ed.), Symposia Intern. Soc. Cell. Biol., Vol. 1, p. 263. Academic
Press, New York.
LITERATURE
CITED
353
11.5. Microscopy of Negatively Stained Material
Valentine and Home (1962) point out that one should not use a small
objective aperture (or an unusually long objective focal length) in working with negatively stained material. To do so minimizes contrast differences between the dense background material and the specimen, rather
than exaggerating it, as is the case when the background density is
minimal.
If one wants maximal contrast from negatively stained material, one
should also operate the microscope at the lowest practical accelerating
voltage. Below 60 kv the contrast of all material rises nearly in inverse
proportion to the high tension. For the future it would seem that the
development of a truly low voltage electron microscope would offer the
best possibility of visualizing small, light molecules negatively stained.
Thus, if one accepts a contrast limit of about 20-30 A based on an
accelerating voltage of 60 kv, a voltage reduction to 15 kv should increase
the contrast nearly four times. This would be expected to give a limit of
visibility to negatively stained material of 5-8 A.
LITERATURE CITED
Brenner, S., and Home, R. W. (1959). Biochim.
Biophys.
Acta 34, 103.
Farrant, J. L. (1954). Biochim.
Biophys.
Acta 13, 569.
Hall, C. E. (1955). /. Biophys.
Biochem.
Cytol. 1, 1.
Huxley, H. E. (1956). In "Electron Microscopy," Proc. Stockholm Conf., p. 260. Almqvist
& Wiksell, Stockholm.
Huxley, H. E. (1962). In "Electron Microscopy" (Proc. 5th Intern. Congr.), Vol. 2, p. O-l.
Academic Press, New York.
Huxley, H. E., and Zubay, G. (1960). Proc. European
Regional
Conf. Electron
Microscopy,
Delft, 2, 703. De Nederlandse Vereniging voor E. M., Delft.
Home, R. W., and Brenner, S. (1960). 4th Intern.
Conf. Electron
Microscopy,
Berlin,
1958, 2, 265. Springer, Berlin.
Valentine, R. C. (1959). Nature
184, 1838.
Valentine, R. C. (1960). Proc. European
Regional
Conf. Electron
Microscopy,
Delft,
2,
708. De Nederlandse Vereniging voor E. M., Delft.
Valentine, R. C., and Home, R. W. (1962). In "The Interpretation of Ultrastructure"
(R. J. C. Harris, ed.), Symposia Intern. Soc. Cell. Biol., Vol. 1, p. 263. Academic
Press, New York.