Biology Reference
In-Depth Information
Fig. 2.1
Schema indicating the morpho-functional processes during active growth in
Laminariales. In distal thallus regions, photosynthetic carbon fixation via RUBISCO and biosyn-
thetic processes in the Calvin-Benson cycle are connected through translocation of low-weight
molecular sugars (e.g., mannitol) with anaplerotic processes mediated by LICF in the intercalary
meristem.
PGA
, 3-phosphoglycerate;
GAP
, glyceraldehyde-3-phosphate;
PK
, Pyruvate kinase;
PD
, Pyruvate dehydrogenase;
PEP-CK
, Phosphoenolpyruvate carboxykinase;
PEP
, Phospoenol-
pyruvate;
RuBP
, ribulose 1,5-bisphosphate
anaplerotic reactions (Kremer
1981
; Cabello-Pasini and Alberte
2001b
). In
Rhodophyta, anaplerotic consumption of storage carbohydrates has been less stud-
ied. In
Gelidium coulteri
grown under
N
starvation, rates of LICF were relatively
low (1-7%), floridoside was rapidly consumed in glycolysis, and an important
fraction of the
14
C labeling was allocated to amino acids of the tricarboxylic
acids cycle (Macler
1986
). This pattern has been found in other Rhodophyta and
