It has long been theorized that carbon allocation, in addition to the carbon source and to kinetic isotopic effects associated with a particular lipid biosynthetic pathway, plays an important role in shaping the carbon isotopic composition ((13)C/(12)C) of lipids (Park and Epstein, 1961). If the latter two factors are properly constrained, valuable information about carbon allocation during lipid biosynthesis can be obtained from carbon isotope measurements. Published work of Chikaraishi et al. (2004) showed that leaf lipids isotopic shifts from bulk leaf tissue Δδ(13)C(bk-lp) (defined as δ(13)C(bulkleaftissue)-δ(13)C(lipid)) are pathway dependent: the acetogenic (ACT) pathway synthesizing fatty lipids has the largest isotopic shift, the mevalonic acid (MVA) pathway synthesizing sterols the lowest and the phytol synthesizing 1-deoxy-D-xylulose 5-phosphate (DXP) pathway gives intermediate values. The differences in Δδ(13)C(bk-lp) between C3 and C4 plants Δδ(13)C(bk-lp,C4-C3) are also pathway-dependent: Δδ(13)C(ACT)(bk-lp,C4-C3) > Δδ(13)C(DXP(bk-lp,C4-C3) > Δδ(13)C(MVA)(bk-lp,C4-C3). These pathway-dependent differences have been interpreted as resulting from kinetic isotopic effect differences of key but unspecified biochemical reactions involved in lipids biosynthesis between C3 and C4 plants. After quantitatively considering isotopic shifts caused by (dark) respiration, export-of-carbon (to sink tissues) and photorespiration, we propose that the pathway-specific differences Δδ(13)C(bk-lp,C4-C3) can be successfully explained by C4-C3 carbon allocation (flux) differences with greatest flux into the ACT pathway and lowest into the MVA pathways (when flux is higher, isotopic shift relative to source is smaller). Highest carbon allocation to the ACT pathway appears to be tied to the most stringent role of water-loss-minimization by leaf waxes (composed mainly of fatty lipids) while the lowest carbon allocation to the MVA pathway can be largely explained by the fact that sterols act as regulatory hormones and membrane fluidity modulators in rather low concentrations.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.phytochem.2014.12.005 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Accuracy of two-compartment modelling of gas exchange with ventilation-perfusion mismatch in inhalational anesthesia.
Anesthesiology
January 2025
Department of Critical Care, Melbourne Medicine School, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia.
Background: Multi-compartment computer models of heterogeneity in alveolar ventilation-perfusion ratios (VA/Q scatter) across the lung explain the significant alveolar-arterial (A-a) partial pressure gradients and associated alveolar dead-space fractions (VDA/VA) seen in anesthetized patients for both carbon dioxide and for anesthetic gases of different blood solubilities. However, the accuracy of a simpler two-compartment model of VA/Q scatter to do this has not been tested or compared to calculations from the traditional Riley model with "ideal", unventilated (shunt) and unperfused (deadspace) compartments.
Methods: Measurements of gas partial pressures in inspired and expired gas and arterial and mixed venous blood from 29 patients undergoing inhalational general anesthesia for cardiac surgery was used to compare the accuracy of two simple models of VA/Q scatter and lung gas exchange in predicting measured alveolar and arterial partial pressure differences, and associated alveolar dead-space calculations for the modern anesthetic gases isoflurane, sevoflurane and desflurane.
The plastidial glucan phosphorylase modulates maltodextrin metabolism and affects starch parameters in Arabidopsis thaliana.
J Exp Bot
January 2025
Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, 14476 Potsdam-Golm, Germany.
The plastidial α-glucan phosphorylase (PHS1) can catalyze the elongation and degradation of glucans, but its exact physiological role in plants is not completely deciphered. A plethora of studies have indicated that PHS1 is involved in transitory starch turnover, both in photosynthetic tissues as well as reserve starch accumulation in sink organs of multiple species, by exerting its effects on the plastidial maltodextrin pools. Recent studies have also established its role in the mobilization of short maltooligosaccharides (MOSs), thereby assisting in starch granule initiation.
View Article and Find Full Text PDFThe impact of carbon emissions trading on green total factor productivity based on evidence from a quasi-natural experiment.
Sci Rep
January 2025
Faculty of Social Sciences, University of Lodz, ul. Prez, prez. Gabriela Narutowicza 68, 90-136, Łódź, Poland.
Based on a balanced panel dataset of 272 prefecture-level cities from 2000 to 2022, this paper systematically investigates the impact of the carbon emissions trading system on green total factor productivity and its underlying mechanisms from an integrated perspective of overall, dynamic, and spatial dimensions. The findings reveal that (1) the carbon emissions trading system significantly enhances regional total factor productivity, primarily by optimizing resource allocation efficiency and strengthening regional competitiveness. (2) From a dynamic perspective, the policy effect exhibited a U-shaped relationship: from 2013 to 2018, green total factor productivity was suppressed due to underdeveloped market mechanisms and the policy environment; after 2018, with market maturation and policy stabilization, the policy effects improved significantly.
View Article and Find Full Text PDFGrowth decline in European beech associated with temperature-driven increase in reproductive allocation.
Proc Natl Acad Sci U S A
February 2025
Forest Biology Center, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland.
Climate change is impacting forests in complex ways, with indirect effects arising from interactions between tree growth and reproduction often overlooked. Our 43-y study of European beech () showed that rising summer temperatures since 2005 have led to more frequent seed production events. This shift increases reproductive effort but depletes the trees' stored resources due to insufficient recovery periods between seed crops.
View Article and Find Full Text PDFEnhancing astaxanthin production from Chromochloris zofingiensis via blue light and exogenous inducers in plate photobioreactors.
Bioresour Technol
January 2025
Engineering Research Center of Watershed Carbon Neutrality of Ministry of Education, and Center for Algae Innovation & Engineering Research, School of Resources and Environment, Nanchang University, Nanchang 330031, PR China; College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, PR China. Electronic address:
This study investigates the photoinduction techniques for the maximization of astaxanthin production in Chromochloris zofingiensis following heterotrophic growth. Leveraging blue light, this study enhanced carbon allocation by suppressing the tricarboxylic acid cycle and activating the methylerythritol phosphate and pentose phosphate pathways to facilitate astaxanthin accumulation. Under blue light, an astaxanthin content of 5.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!