80
EDWARD C. CANTINO AND JAMES S. LOVETT
characteristics of an organism which are expressions of its adaptation to
special circumstances normally met in its particular environment.
What, then, do the states of dormancy in bacteria and Blastocladiella
have in common? To begin with, the number of quantitative chemical
differences between bacterial spores and vegetative cells (Halvorson and
Church, 1957) is rather high, as it is between RS and OC cells of
Blastocladiella.
For example, bacterial spores have higher levels of
organic phosphorus and lower levels of free amino-acid pools, as do the
RS cells of B. emersonii. Sporulation in Bacillus sphaericus is stimulated
by bicarbonate (Powell and Hunter, 1955), as well as ketoglutarate.
Sporulation was also improved in a weakly sporulating strain of Bacillus
coagulans by the addition of ketoglutarate, succinate or malate (Amaha
et al., 1956). Thus, bicarbonate induces sporulation in some bacteria, and
ketoglutarate can be substituted for it; this very thing occurs with
Blastocladiella (Cantino, 1951). Such results, together with other observations, led to the notion that the tricarboxylic acid cycle played a
critical role in the formation of RS cells in Blastocladiella (Cantino and
Turian, 1959; Cantino, 1961a; see also, Section III, D). From the report
by Behal (1959) on the sporulation of Aspergillus niger, it appears as if
the tricarboxylic acid cycle is implicated in the process of spore formation by an aquatic Phycomycete, an Ascomycete, and bacteria, and in
two of these triggering effects are brought about by bicarbonate and/or
Krebs cycle intermediates. Parenthetically, it can be noted that
numerous morphological effects of C0 2 and/or bicarbonate have been
reported over the years for diverse kinds of organisms; it will be
interesting to learn how many of these phenomena are seated somewhere
in the tricarboxylic acid cycle (e.g., the effect of C0 2 upon arthrospore
formation in Trichophyton, Chin and Knight, 1957; sex differentiation
in Hydra, Loomis, 1957; differentiation of Fundulus
blastoderms,
Trinkaus, 1956 ; resting cyst formation in Colpoda, Taylor and Strickland,
1939; growth of the yeast phase of Sporotrichum, Mariât, 1960; and the
induction of yeast-like cells of Mucor rouxii by 100% C0 2 , Bartnicki -
Garcia and Nickerson, 1959—so strikingly reminiscent of the induction
of RS cells in Blastocladia by 100% C0 2 ; Emerson and Cantino, 1948).
Another similarity between dormant endospores and resistant
sporangia lies in the nature of electron transport. Relative to vegetative
cells, spore extracts apparently possess a functional hexose monophosphate shunt which leads to pyruvate (Doi et ah, 1959; however, see
Goldman and Blumenthal, 1960), a low level of cytochrome c (Doi,
1961), and a relatively high level of a flavin-containing DPNH oxidizing
system (Doi and Halvorson, 1961). In B. emersonii, glucose-6-phosphate
and 6-phosphogluconic dehydrogenases are the only enzymes (Lovett
and Cantino, 1960b) known so far to rise rapidly during maturation of
EDWARD C. CANTINO AND JAMES S. LOVETT
characteristics of an organism which are expressions of its adaptation to
special circumstances normally met in its particular environment.
What, then, do the states of dormancy in bacteria and Blastocladiella
have in common? To begin with, the number of quantitative chemical
differences between bacterial spores and vegetative cells (Halvorson and
Church, 1957) is rather high, as it is between RS and OC cells of
Blastocladiella.
For example, bacterial spores have higher levels of
organic phosphorus and lower levels of free amino-acid pools, as do the
RS cells of B. emersonii. Sporulation in Bacillus sphaericus is stimulated
by bicarbonate (Powell and Hunter, 1955), as well as ketoglutarate.
Sporulation was also improved in a weakly sporulating strain of Bacillus
coagulans by the addition of ketoglutarate, succinate or malate (Amaha
et al., 1956). Thus, bicarbonate induces sporulation in some bacteria, and
ketoglutarate can be substituted for it; this very thing occurs with
Blastocladiella (Cantino, 1951). Such results, together with other observations, led to the notion that the tricarboxylic acid cycle played a
critical role in the formation of RS cells in Blastocladiella (Cantino and
Turian, 1959; Cantino, 1961a; see also, Section III, D). From the report
by Behal (1959) on the sporulation of Aspergillus niger, it appears as if
the tricarboxylic acid cycle is implicated in the process of spore formation by an aquatic Phycomycete, an Ascomycete, and bacteria, and in
two of these triggering effects are brought about by bicarbonate and/or
Krebs cycle intermediates. Parenthetically, it can be noted that
numerous morphological effects of C0 2 and/or bicarbonate have been
reported over the years for diverse kinds of organisms; it will be
interesting to learn how many of these phenomena are seated somewhere
in the tricarboxylic acid cycle (e.g., the effect of C0 2 upon arthrospore
formation in Trichophyton, Chin and Knight, 1957; sex differentiation
in Hydra, Loomis, 1957; differentiation of Fundulus
blastoderms,
Trinkaus, 1956 ; resting cyst formation in Colpoda, Taylor and Strickland,
1939; growth of the yeast phase of Sporotrichum, Mariât, 1960; and the
induction of yeast-like cells of Mucor rouxii by 100% C0 2 , Bartnicki -
Garcia and Nickerson, 1959—so strikingly reminiscent of the induction
of RS cells in Blastocladia by 100% C0 2 ; Emerson and Cantino, 1948).
Another similarity between dormant endospores and resistant
sporangia lies in the nature of electron transport. Relative to vegetative
cells, spore extracts apparently possess a functional hexose monophosphate shunt which leads to pyruvate (Doi et ah, 1959; however, see
Goldman and Blumenthal, 1960), a low level of cytochrome c (Doi,
1961), and a relatively high level of a flavin-containing DPNH oxidizing
system (Doi and Halvorson, 1961). In B. emersonii, glucose-6-phosphate
and 6-phosphogluconic dehydrogenases are the only enzymes (Lovett
and Cantino, 1960b) known so far to rise rapidly during maturation of