@article{stoop_chilton_pharr_1996, title={Substrate stereospecificity of the NAD-dependent mannitol dehydrogenase from celery}, volume={43}, ISSN={["0031-9422"]}, DOI={10.1016/S0031-9422(96)00423-2}, abstractNote={The NAD-dependent mannitol dehydrogenase (MTD) of celery catalyses the interconversion of d-mannitol and d-mannose. This 1-oxidoreductase is uniquely different from all NAD-dependent polyol dehydrogenases described to date, which are 2-oxidoreductases. The stereospecificity of mannitol dehydrogenase was tested in the oxidative direction in the presence of polyol and NAD cofactor and in the reductive direction in the presence of aldose and NADH. The enzyme would be expected to show the same stereospecificity in either direction. The stereospecificity in the reductive direction was tested by attempted reduction of all eight d- and l-pentoses and 15 of the 16 d- and l-hexoses. Stereospecificity in the oxidative direction was tested with the four pentitols and four of the hexitols. Mannitol dehydrogenase showed a marked preference for aldopentose and aldohexose substrates with the same absolute configuration at C-2 as that of d-mannose. Reduction of l-dose by mannitol dehydrogenase was the only exception to the stated stereochemical preference among 23 aldoses and eight alditols tested. The sugar d-threose that occurs rarely in nature is a competitive inhibitor (Ki = 18 mM) of mannitol oxidation. The physiologically important hexitols, galactitol and glucitol, are oxidized by MTD to aldoses that are not metabolized by higher plants.}, number={6}, journal={PHYTOCHEMISTRY}, author={Stoop, JMH and Chilton, WS and Pharr, DM}, year={1996}, month={Dec}, pages={1145–1150} }
 @article{stoop_pharr_1994, title={Growth substrate and nutrient salt environment alter mannitol-to-hexose partitioning in celery petioles}, volume={119}, number={2}, journal={Journal of the American Society for Horticultural Science}, author={Stoop, J. M. H. and Pharr, D. M.}, year={1994}, pages={237} }
 @article{stoop_pharr_1994, title={MANNITOL METABOLISM IN CELERY STRESSED BY EXCESS MACRONUTRIENTS}, volume={106}, ISSN={["0032-0889"]}, DOI={10.1104/pp.106.2.503}, abstractNote={The effect of excess macronutrients in the root environment on mannitol and sucrose metabolism was investigated in celery (Apium graveolens L. var dulce [Mill.] Pers.). Plant growth was inhibited progressively as macronutrient concentration in the media, as measured by electrical conductivity (E.C.), increased from 1.0 to 11.9 decisiemens m-1. Plants grown for 35 d at higher E.C. had a lower water content but similar dry weight in their roots, leaves, and petioles compared to plants grown at lower E.C. Macronutrient concentrations of leaves, roots, and petioles were not affected by the imposed stress, indicating that the macronutrient stress resulted in a water-deficit stress response rather than a salt-specific response. Mannitol accumulated in sink tissues and was accompanied by a drastic decrease in activity of mannitol-1-oxidoreductase. Sucrose concentration and activities of sucrose-metabolizing enzymes in sink tissues were not affected by the macronutrient stress. Mature leaves exhibited increased concentrations of both mannitol and sucrose, together with increased activity of mannose-6-phosphate reductase and sucrose phosphate synthase, in response to macronutrient stress. Thus, mannitol accumulation in osmotically stressed celery is regulated by diminished catabolism in sink tissues and increased capacity for mannitol biosynthesis in source leaves.}, number={2}, journal={PLANT PHYSIOLOGY}, author={STOOP, JMH and PHARR, DM}, year={1994}, month={Oct}, pages={503–511} }
 @article{stoop_pharr_1993, title={EFFECT OF DIFFERENT CARBON-SOURCES ON RELATIVE GROWTH-RATE, INTERNAL CARBOHYDRATES, AND MANNITOL 1-OXIDOREDUCTASE ACTIVITY IN CELERY SUSPENSION-CULTURES}, volume={103}, ISSN={["1532-2548"]}, DOI={10.1104/pp.103.3.1001}, abstractNote={Little information exists concerning the biochemical route of mannitol catabolism in higher plant cells. In this study, the role of a recently discovered mannitol 1-oxidoreductase (MDH) in mannitol catabolism was investigated. Suspension cultures of celery (Apium graveolens L. var dulce [Mill.] Pers.) were successfully grown on nutrient media with either mannitol, mannose, or sucrose as the sole carbon source. Cell cultures grown on any of the three carbon sources did not differ in relative growth rate, as measured by packed cell volume, but differed drastically in internal carbohydrate concentration. Mannitol-grown cells contained high concentrations of mannitol and extremely low concentrations of sucrose, fructose, glucose, and mannose. Sucrose-grown cells had high concentrations of sucrose early in the growth cycle and contained a substantial hexose pool. Mannose-grown cells had a high mannose concentration early in the cycle, which decreased during the growth cycle, whereas their internal sucrose concentrations remained relatively constant during the entire growth cycle. Celery suspension cultures on all three carbon substrates contained an NAD-dependent MDH. Throughout the growth cycle, MDH activity was 2- to 4-fold higher in mannitol-grown cells compared with sucrose- or mannose-grown cells, which did not contain detectable levels of mannitol, indicating that MDH functions pre-dominantly in an oxidative capacity in situ. The MDH activity observed in celery cells was 3-fold higher than the minimum amount required to account for the observed rate of mannitol utilization from the media. Cultures transferred from mannitol to mannose underwent a decrease in MDH activity over a period of days, and transfer from mannose to mannitol resulted in an increase in MDH activity. These data provide strong evidence that MDH plays an important role in mannitol utilization in celery suspension cultures.}, number={3}, journal={PLANT PHYSIOLOGY}, author={STOOP, JMH and PHARR, DM}, year={1993}, month={Nov}, pages={1001–1008} }
 @misc{pharr_stoop_1993, title={Mannitol oxidoreductase isolated from vascular plants}, volume={5268288}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Pharr, D. M. and Stoop, J. M. H.}, year={1993} }
 @article{stoop_willits_peet_nelson_1991, title={Carbon Gain and Photosynthetic Response of Chrysanthemum to Photosynthetic Photon Flux Density Cycles}, volume={96}, ISSN={0032-0889 1532-2548}, url={http://dx.doi.org/10.1104/pp.96.2.529}, DOI={10.1104/pp.96.2.529}, abstractNote={Most models of carbon gain as a function of photosynthetic irradiance assume an instantaneous response to increases and decreases in irradiance. High- and low-light-grown plants differ, however, in the time required to adjust to increases and decreases in irradiance. In this study the response to a series of increases and decreases in irradiance was observed in Chrysanthemum x morifolium Ramat. "Fiesta" and compared with calculated values assuming an instantaneous response. There were significant differences between high- and low-light-grown plants in their photosynthetic response to four sequential photosynthetic photon flux density (PPFD) cycles consisting of 5-minute exposures to 200 and 400 micromoles per square meter per second (mumol m(-2)s(-1)). The CO(2) assimilation rate of high-light-grown plants at the cycle peak increased throughout the PPFD sequence, but the rate of increase was similar to the increase in CO(2) assimilation rate observed under continuous high-light conditions. Low-light leaves showed more variability in their response to light cycles with no significant increase in CO(2) assimilation rate at the cycle peak during sequential cycles. Carbon gain and deviations from actual values (percentage carbon gain over- or underestimation) based on assumptions of instantaneous response were compared under continuous and cyclic light conditions. The percentage carbon gain overestimation depended on the PPFD step size and growth light level of the leaf. When leaves were exposed to a large PPFD increase, the carbon gain was overestimated by 16 to 26%. The photosynthetic response to 100 mumol m(-2) s(-1) PPFD increases and decreases was rapid, and the small overestimation of the predicted carbon gain, observed during photosynthetic induction, was almost entirely negated by the carbon gain underestimation observed after a decrease. If the PPFD cycle was 200 or 400 mumol m(-2) s(-1), high- and low-light leaves showed a carbon gain overestimation of 25% that was not negated by the underestimation observed after a light decrease. When leaves were exposed to sequential PPFD cycles (200-400 mumol m(-2) s(-1)), carbon gain did not differ from leaves exposed to a single PPFD cycle of identical irradiance integral that had the same step size (200-400-200 mumol m(-2) s(-1)) or mean irradiance (200-300-200 mumol m(-2) s(-1)).}, number={2}, journal={Plant Physiology}, publisher={Oxford University Press (OUP)}, author={Stoop, Johan M. H. and Willits, Dan H. and Peet, Mary M. and Nelson, Paul V.}, year={1991}, month={Jun}, pages={529–536} }
 @article{stoop_peet_willits_nelson_1990, title={Photosynthetic Dynamics in Chrysanthemum in Response to Single Step Increases and Decreases in Photon Flux Density}, volume={94}, ISSN={0032-0889 1532-2548}, url={http://dx.doi.org/10.1104/pp.94.1.46}, DOI={10.1104/pp.94.1.46}, abstractNote={The time-course of CO(2) assimilation rate and stomatal conductance to step changes in photosynthetic photon flux density (PPFD) was observed in Chrysanthemum x morifolium Ramat. ;Fiesta'. When PPFD was increased from 200 to 600 micromoles per square meter per second, the rate of photosynthetic CO(2) assimilation showed an initial rapid increase over the first minute followed by a slower increase over the next 12 to 38 minutes, with a faster response in low-light-grown plants. Leaves exposed to small step increases (100 micromoles per square meter per second) reached the new steady-state assimilation rate within a minute. Both stomatal and biochemical limitations played a role during photosynthetic induction, but carboxylation limitations seemed to predominate during the first 5 to 10 minutes. Stomatal control during the slow phase of induction was less important in low-light compared to high-light-grown plants. In response to step decreases in PPFD, photosynthetic rate decreased rapidly and a depression in CO(2) assimilation prior to steady-state was observed. This CO(2) assimilation ;dip' was considerably larger for the large step (400 micromoles per square meter per second) than for the small step. The rapid photosynthetic response seems to be controlled by biochemical processes. High- and low-light-grown plants did not differ in their photosynthetic response to PPFD step decreases.}, number={1}, journal={Plant Physiology}, publisher={Oxford University Press (OUP)}, author={Stoop, Johan M. H. and Peet, Mary M. and Willits, Dan H. and Nelson, Paul V.}, year={1990}, month={Sep}, pages={46–53} }