3. C O N S T R U C T I O N A N D USE OF S Y N T H E T I C M E D I A
117
legitimately be included in chemically defined media (Brown, Sanger
and Kitai, 1955), is insulin. Its effects are certainly multiple, not fully
understood, but in general beneficial, though in different systems it has
been reported to abolish aerobic production of lactic acid (Graff and
McCarty, 1958) or stimulate glucose utilization and lactate production
(Lieberman and Ove, 1959; Paul and Pearson, 1960).
Purines and pyrimidines are not invariable constituents of successful
media, so it is probable that most cells are independent of these as
precursors. Differing rates of synthesis of nucleic acids and their
derivatives, however, make the inclusion of bases, or nucleosides,
stimulatory in particular systems. Parker (1961) describes fully the
successive media developed in his laboratory, to which purine and
pyrimidine bases were added and withdrawn, and the eventual inclusion in media 858 and C M R L 1066 of five deoxyribonucleosides.
It is still necessary to admit, as Morgan did in 1958 (Morgan, 1958)
that "it is impossible to state definitely whether purine and pyrimidine
bases, as such, are essential for cell nutrition . . . " . The probability
is high that they are not (Salzman, Eagle and Sebring, 1958), but that
they may be significantly stimulatory (Neuman and Tytell, 1958; Thomson, Paul and Davidson, 1958; Chang, Liepins and Margolish, 1961).
Antibiotics are commonly added to synthetic media, and may affect
the metabolism and utilization of other components of a medium, so it
is desirable to omit them in strict nutritional and metabolic studies.
Paul (1960) lists a number of antibiotics which have been used in a
variety of culture systems, and tabulates references to a series of studies
on ranges of concentrations initiating depression, or complete inhibition,
of growth. Inhibition is not the only possible response, however, for
appropriate concentrations of penicillin or streptomycin have been
shown to stimulate fibroblast growth (Aranda, Fernandez and Fuertes,
1957).
Table I lists references to most of the synthetic media (some supplemented with small amounts of serum, peptone, etc.) which may be
regarded as useful in current practice. The formulae for some of the
more commonly used media, and directions for their preparation, are
to be found in several textbooks, most completely in those of Paul (1960)
and Parker (1961). It is generally best to study carefully the original
papers, giving attention to methods of preparation, sterilization and
storage. For example, the order in which the components are dissolved
in a complete medium, or in a stock solution which makes up part of a
medium, may be important. As emphasized in Chapter 2, glassdistilled water of the highest purity, rather than deionized water, is
generally recommended for preparing defined media, though it is not
widely recognized that the passage of such water through bacteriological
117
legitimately be included in chemically defined media (Brown, Sanger
and Kitai, 1955), is insulin. Its effects are certainly multiple, not fully
understood, but in general beneficial, though in different systems it has
been reported to abolish aerobic production of lactic acid (Graff and
McCarty, 1958) or stimulate glucose utilization and lactate production
(Lieberman and Ove, 1959; Paul and Pearson, 1960).
Purines and pyrimidines are not invariable constituents of successful
media, so it is probable that most cells are independent of these as
precursors. Differing rates of synthesis of nucleic acids and their
derivatives, however, make the inclusion of bases, or nucleosides,
stimulatory in particular systems. Parker (1961) describes fully the
successive media developed in his laboratory, to which purine and
pyrimidine bases were added and withdrawn, and the eventual inclusion in media 858 and C M R L 1066 of five deoxyribonucleosides.
It is still necessary to admit, as Morgan did in 1958 (Morgan, 1958)
that "it is impossible to state definitely whether purine and pyrimidine
bases, as such, are essential for cell nutrition . . . " . The probability
is high that they are not (Salzman, Eagle and Sebring, 1958), but that
they may be significantly stimulatory (Neuman and Tytell, 1958; Thomson, Paul and Davidson, 1958; Chang, Liepins and Margolish, 1961).
Antibiotics are commonly added to synthetic media, and may affect
the metabolism and utilization of other components of a medium, so it
is desirable to omit them in strict nutritional and metabolic studies.
Paul (1960) lists a number of antibiotics which have been used in a
variety of culture systems, and tabulates references to a series of studies
on ranges of concentrations initiating depression, or complete inhibition,
of growth. Inhibition is not the only possible response, however, for
appropriate concentrations of penicillin or streptomycin have been
shown to stimulate fibroblast growth (Aranda, Fernandez and Fuertes,
1957).
Table I lists references to most of the synthetic media (some supplemented with small amounts of serum, peptone, etc.) which may be
regarded as useful in current practice. The formulae for some of the
more commonly used media, and directions for their preparation, are
to be found in several textbooks, most completely in those of Paul (1960)
and Parker (1961). It is generally best to study carefully the original
papers, giving attention to methods of preparation, sterilization and
storage. For example, the order in which the components are dissolved
in a complete medium, or in a stock solution which makes up part of a
medium, may be important. As emphasized in Chapter 2, glassdistilled water of the highest purity, rather than deionized water, is
generally recommended for preparing defined media, though it is not
widely recognized that the passage of such water through bacteriological