Paula Seamon - Academia.edu (original) (raw)

Papers by Paula Seamon

PLANT PHYSIOLOGY, 1988

Two green macroalgae, Codium decorticatum and Udotea flabellum, differ photosynthetically. Codium... more Two green macroalgae, Codium decorticatum and Udotea flabellum, differ photosynthetically. Codium had high O2-sensitive, and Udotea low 02-insensitive, CO2 compensation points; Codium showed a Warburg effect at seawater dissolved inorganic carbon levels and had photorespiratory C02 release, whereas Udotea did not. Seawater dissolved inorganic carbon levels did not saturate photosynthesis. For Codium, but not Udotea, the Warburg effect was increased by ethoxyzolamide, a carbonic anhydrase inhibitor, at high but not low pH. Isolated chloroplasts from both macroalgae showed a Warburg effect that was ethoxyzolamideinsensitive. In both macroalgae, chloroplastic and extrachloroplastic carbonic anhydrase activity was present. P-enolpyruvate carboxykinase (PEPCK) carboxylating activity in Udotea extracts was equivalent to that of ribulose bisphosphate carboxylase, and enzyme activities for C4 acid metabolism and P-enolpyruvate regeneration were sufficient to operate a limited C4-like system. In Udotea, malate and aspartate were earlylabeled photosynthetic products that turned over within 60 seconds. Photorespiratory compounds were much less labeled in Udotea. Low dark fixation rates ruled out Crassulacean acid metabolism. A limited C4-like system, based on PEPCK, is hypothesized to be the mechanism reducing photorespiration in Udotea. Codium showed no evidence of photosynthetic C4 acid metabolism. Marine macroalgae, like terrestrial angiosperms, seem to have diverse photosynthetic modes.

Aquatic Botany, Mar 1, 1989

... Furthermore, enzymatic studies, and 14C pulse-chase data, showing turnover of C4 acids in the... more ... Furthermore, enzymatic studies, and 14C pulse-chase data, showing turnover of C4 acids in the light, suggest that U. flabeUum has a C4-1ike component in its photosynthetic biochemistry, not ... The association between chloroplasts of Codium fragile and the mollusc Elysia viridis ...

PLANT PHYSIOLOGY, 1988

Two green macroalgae, Codium decorticatum and Udotea flabellum, differ photosynthetically. Codium... more Two green macroalgae, Codium decorticatum and Udotea flabellum, differ photosynthetically. Codium had high O2-sensitive, and Udotea low 02-insensitive, CO2 compensation points; Codium showed a Warburg effect at seawater dissolved inorganic carbon levels and had photorespiratory C02 release, whereas Udotea did not. Seawater dissolved inorganic carbon levels did not saturate photosynthesis. For Codium, but not Udotea, the Warburg effect was increased by ethoxyzolamide, a carbonic anhydrase inhibitor, at high but not low pH. Isolated chloroplasts from both macroalgae showed a Warburg effect that was ethoxyzolamideinsensitive. In both macroalgae, chloroplastic and extrachloroplastic carbonic anhydrase activity was present. P-enolpyruvate carboxykinase (PEPCK) carboxylating activity in Udotea extracts was equivalent to that of ribulose bisphosphate carboxylase, and enzyme activities for C4 acid metabolism and P-enolpyruvate regeneration were sufficient to operate a limited C4-like system. In Udotea, malate and aspartate were earlylabeled photosynthetic products that turned over within 60 seconds. Photorespiratory compounds were much less labeled in Udotea. Low dark fixation rates ruled out Crassulacean acid metabolism. A limited C4-like system, based on PEPCK, is hypothesized to be the mechanism reducing photorespiration in Udotea. Codium showed no evidence of photosynthetic C4 acid metabolism. Marine macroalgae, like terrestrial angiosperms, seem to have diverse photosynthetic modes.

Aquatic Botany, Mar 1, 1989

... Furthermore, enzymatic studies, and 14C pulse-chase data, showing turnover of C4 acids in the... more ... Furthermore, enzymatic studies, and 14C pulse-chase data, showing turnover of C4 acids in the light, suggest that U. flabeUum has a C4-1ike component in its photosynthetic biochemistry, not ... The association between chloroplasts of Codium fragile and the mollusc Elysia viridis ...