C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves

2003 ◽  
Vol 26 (8) ◽  
pp. 1191-1197 ◽  
Author(s):  
S. VON CAEMMERER
Keyword(s):  
C4 Photosynthesis ◽  
Diffusion Limitations ◽  
Co2 Diffusion ◽  
Internal Co2

scholarly journals Mesophyll conductance in cotton bracts: anatomically determined internal CO2 diffusion constraints on photosynthesis

2018 ◽  
Author(s):  
Jimei Han ◽  
Zhangying Lei ◽  
Jaume Flexas ◽  
Yujie Zhang ◽  
Marc Carriquí ◽  
...  
Keyword(s):  
Mesophyll Conductance ◽  
Co2 Diffusion ◽  
Internal Co2 ◽  
Cotton Bracts

scholarly journals Decomposition of Calcium Oxalate Crystals in Colobanthus quitensis under CO2 Limiting Conditions

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1307
Author(s):  
Olman Gómez-Espinoza ◽  
Daniel González-Ramírez ◽  
Panagiota Bresta ◽  
George Karabourniotis ◽  
León A. Bravo
Keyword(s):  
Calcium Oxalate ◽  
Electron Transport Rate ◽  
Relative Size ◽  
Oxalate Oxidase ◽  
Stress Factors ◽  
Calcium Oxalate Crystals ◽  
Colobanthus Quitensis ◽  
Diffusion Limitations ◽  
Co2 Diffusion ◽  
The Antarctic

Calcium oxalate (CaOx) crystals are widespread among plant species. Their functions are not yet completely understood; however, they can provide tolerance against multiple environmental stress factors. Recent evidence suggested that CaOx crystals function as carbon reservoirs since its decomposition provides CO2 that may be used as carbon source for photosynthesis. This might be advantageous in plants with reduced mesophyll conductance, such as the Antarctic plant Colobanthus quitensis, which have shown CO2 diffusion limitations. In this study, we evaluate the effect of two CO2 concentrations in the CaOx crystals decomposition and chlorophyll fluorescence of C. quitensis. Plants were exposed to airflows with 400 ppm and 11.5 ppm CO2 and the number and relative size of crystals, electron transport rate (ETR), and oxalate oxidase (OxO) activity were monitored along time (10 h). Here we showed that leaf crystal area decreases over time in plants with 11.5 ppm CO2, which was accompanied by increased OxO activity and only a slight decrease in the ETR. These results suggested a relation between CO2 limiting conditions and the CaOx crystals decomposition in C. quitensis. Hence, crystal decomposition could be a complementary endogenous mechanism for CO2 supply in plants facing the Antarctic stressful habitat.

C4 photosynthesis and CO2 diffusion

2008 ◽  
pp. 95-115 ◽  
Author(s):  
S. von Caemmerer ◽  
J. R. Evans ◽  
A. B. Cousins ◽  
M. R. Badger ◽  
R. T. Furbank
Keyword(s):  
C4 Photosynthesis ◽  
Co2 Diffusion

C4 mechanisms in aquatic angiosperms: comparisons with terrestrial C4 systems

2002 ◽  
Vol 29 (3) ◽  
pp. 379 ◽  
Author(s):  
George Bowes ◽  
Srinath K. Rao ◽  
Gonzalo M. Estavillo ◽  
Julia B. Reiskind
Keyword(s):  
C4 Photosynthesis ◽  
Hydrilla Verticillata ◽  
Terrestrial Plants ◽  
Relative Growth ◽  
Kranz Anatomy ◽  
Low Co2 ◽  
C4 Species ◽  
Internal Co2 ◽  
Photosynthesis Regulation ◽  
Marine Macroalga

Aquatic C4 photosynthesis probably arose in response to dissolved CO2 limitations, possibly before its advent in terrestrial plants. Of over 7600 C4 species, only about a dozen aquatic species are identified. Amphibious Eleocharis species (sedges) have C3–C4 photosynthesis and Kranz anatomy in aerial, but not submersed, leaves. Aquatic grasses have aerial and submersed leaves with C4 or C3–C4 photosynthesis and Kranz anatomy, but some lack Kranz anatomy in the submersed leaves. Two freshwater submersed monocots, Hydrilla verticillata and possibly Egeria densa, are C4 NADP-malic enzyme (NADP-ME) species. A marine macroalga, Udotea flabellum (Chlorophyta), and possibly a diatom, are C4, so it is not confined to angiosperms. Submersed C4 species differ from terrestrial in that β-carboxylation is cytosolic with chloroplastic decarboxylation and Rubisco carboxylation, so the C4 and Calvin cycles operate in the same cell without Kranz anatomy. Unlike terrestrial plants, Hydrilla is a facultative C4 that shifts from C3 to C4 in low [CO2]. It is well documented, with C4 gas exchange and pulse-chase characteristics, enzyme kinetics and localization, high internal [CO2], relative growth rate, and quantum yield studies. It has multiple phosphoenolpyruvate carboxylase isoforms with C3-like sequences. Hvpepc4 appears to be the photosynthetic form induced in C4 leaves, but it differs from terrestrial C4 isoforms in lacking a C4 signature Serine. The molecular mass of NADP-ME (72 kDa) also resembles a C3 isoform. Hydrilla belongs to the ancient Hydrocharitaceae family, and gives insight to early C4 development. Hydrilla is an excellent ‘minimalist’ system to study C4 photosynthesis regulation without anatomical complexities.

Modeling the Effects of Diffusion Limitations on Nitrogen-15 Isotope Dilution Experiments with Soil Aggregates

2003 ◽  
Vol 67 (2) ◽  
pp. 677-677
Author(s):  
John B. Cliff ◽  
Peter J. Bottomley ◽  
Roy Haggerty ◽  
David D. Myrold
Keyword(s):  
Isotope Dilution ◽  
Soil Aggregates ◽  
Diffusion Limitations ◽  
Dilution Experiments

scholarly journals Structure-Properties Correlation of Cross-Linked Penicillin G Acylase Crystals

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 451
Author(s):  
Marta Kubiak ◽  
Janine Mayer ◽  
Ingo Kampen ◽  
Carsten Schilde ◽  
Rebekka Biedendieck
Keyword(s):  
Mechanical Stability ◽  
Structural Characteristics ◽  
Penicillin G ◽  
Bacillus Species ◽  
Diffusion Limitations ◽  
Small Water ◽  
Long Term Stability ◽  
Atomic Force ◽  
First Time

In biocatalytic processes, the use of free enzymes is often limited due to the lack of long-term stability and reusability. To counteract this, enzymes can be crystallized and then immobilized, generating cross-linked enzyme crystals (CLECs). As mechanical stability and activity of CLECs are crucial, different penicillin G acylases (PGAs) from Gram-positive organisms have proven to be promising candidates for industrial production of new semisynthetic antibiotics, which can be crystallized and cross-linked to characterize the resulting CLECs regarding their mechanical and catalytic properties. The greatest hardness and Young’s modulus determined by indentation with an atomic force microscope were observed for CLECs of Bacillus species FJAT-PGA CLECs (26 MPa/1450 MPa), followed by BmPGA (Priestia megaterium PGA, 23 MPa/1170 MPa) and BtPGA CLECs (Bacillus thermotolerans PGA, 11 MPa/614 MPa). In addition, FJAT- and BtPGA CLECs showed up to 20-fold higher volumetric activities compared to BmPGA CLECs. Correlation to structural characteristics indicated that a high solvent content and low number of cross-linking residues might lead to reduced stability. Furthermore, activity seems to be restricted by small water channels due to severe diffusion limitations. To the best of our knowledge, we show for the first time in this study that the entire process chain for the characterization of diverse industrially relevant enzymes can be performed at the microliter scale to discover the most important relationships and limitations.

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