282
GEORGE G. LATIES
acteristics of avocado slice respiration through the ripening period are
at least consistent with this suggestion.
Whereas the endogenous respiration rate of slices remains constant
throughout the ripening period, the respiration of preclimacteric slices
is doubled by dinitrophenol, while that of slices at the climacteric
maximum remains unaffected. Since the specific respiratory increment
evoked by dinitrophenol in preclimacteric slices is approximately equal
on an absolute basis to the respiratory rise manifested by intact fruits
during the climacteric, it is attractive to consider that the constancy of
slice respiration under the circumstances is the consequence of the
replacement of an appreciable fraction of the basal respiration of preclimacteric fruit by a phosphorylative respiratory component which develops with ripening. The absence of any response to dinitrophenol in
slices at the climacteric maximum would then signify either that the
respiration is endogenously uncoupled, as suggested by Millerd et al.,
or that the phosphorylative reactions associated with respiration are no
longer limiting the respiratory rate.
The very tentative interpretation just ventured in explanation of the
respiratory behavior of the avocado fruit during the climacteric draws on
a body of information relating to the respiratory characteristics of a
variety of fleshy organs. It is manifestly but one of many possible interpretations, and it is offered simply as a working hypothesis in anticipation of further experimentation on the respiration of fruits.
V. CONCLUSION
In the foregoing discussion a considerably restricted interpretation has
been offered of the manner in which the regulation of respiration rate
is achieved, and of the way in which respiration is linked to cellular
work. In general, glycolysis has tacitly been considered to be of the
classical Embden-Meyerhof type, while aerobic respiration was presumed to proceed through the tricarboxylic acid cycle. At least in such
systems, in which oxidation is accompanied by phosphorylation, there is
good evidence that the regulation of respiration rate is achieved by the
phosphorylative process, that is, by the concentration and rate of regeneration of acceptors for metabolically produced high-energy phosphate. Many of the processes comprising cellular work appear to depend
upon the phosphorylative metabolism. By the utilization of high-energy
intermediates of respiration in the performance of cellular work, with the
consequent regeneration of phosphate acceptors, the work processes in
turn affect the respiration rate. The system is self-regulatory.
In many of the objects which have been examined there has been evidence for more than one type of respiratory process within a given
GEORGE G. LATIES
acteristics of avocado slice respiration through the ripening period are
at least consistent with this suggestion.
Whereas the endogenous respiration rate of slices remains constant
throughout the ripening period, the respiration of preclimacteric slices
is doubled by dinitrophenol, while that of slices at the climacteric
maximum remains unaffected. Since the specific respiratory increment
evoked by dinitrophenol in preclimacteric slices is approximately equal
on an absolute basis to the respiratory rise manifested by intact fruits
during the climacteric, it is attractive to consider that the constancy of
slice respiration under the circumstances is the consequence of the
replacement of an appreciable fraction of the basal respiration of preclimacteric fruit by a phosphorylative respiratory component which develops with ripening. The absence of any response to dinitrophenol in
slices at the climacteric maximum would then signify either that the
respiration is endogenously uncoupled, as suggested by Millerd et al.,
or that the phosphorylative reactions associated with respiration are no
longer limiting the respiratory rate.
The very tentative interpretation just ventured in explanation of the
respiratory behavior of the avocado fruit during the climacteric draws on
a body of information relating to the respiratory characteristics of a
variety of fleshy organs. It is manifestly but one of many possible interpretations, and it is offered simply as a working hypothesis in anticipation of further experimentation on the respiration of fruits.
V. CONCLUSION
In the foregoing discussion a considerably restricted interpretation has
been offered of the manner in which the regulation of respiration rate
is achieved, and of the way in which respiration is linked to cellular
work. In general, glycolysis has tacitly been considered to be of the
classical Embden-Meyerhof type, while aerobic respiration was presumed to proceed through the tricarboxylic acid cycle. At least in such
systems, in which oxidation is accompanied by phosphorylation, there is
good evidence that the regulation of respiration rate is achieved by the
phosphorylative process, that is, by the concentration and rate of regeneration of acceptors for metabolically produced high-energy phosphate. Many of the processes comprising cellular work appear to depend
upon the phosphorylative metabolism. By the utilization of high-energy
intermediates of respiration in the performance of cellular work, with the
consequent regeneration of phosphate acceptors, the work processes in
turn affect the respiration rate. The system is self-regulatory.
In many of the objects which have been examined there has been evidence for more than one type of respiratory process within a given