Light-Enhanced Dark 14CO2 Fixation by Leaves in Relation to the C4 Dicarboxylic Acid Pathway of Photosynthesis

1977 ◽  
Vol 4 (5) ◽  
pp. 833 ◽  
Author(s):  
AS Raghavendra ◽  
VSR Das
Keyword(s):  
Carbon Fixation ◽  
C4 Plants ◽  
C3 Plant ◽  
14Co2 Fixation ◽  
Detached Leaves ◽  
Dark Fixation ◽  
Primary Acceptor ◽  
Sugar Phosphates ◽  
Amaranthus Paniculatus ◽  
Acid Pathway

The technique of light-enhanced dark carbon dioxide fixation has been employed to critically examine the primary route of CO2 incorporation in leaves of two C4 plants (Setaria italica and Amaranthus paniculatus) in comparison with that of a C3 plant (Rumex vesicarius). Prior illumination of detached leaves enhanced their dark 14CO2 fixation five- to tenfold over that of unilluminated leaves. No variation was observed among C3 and C4 plants, in the conditions required for their light-enhanced dark fixation. Fifty to sixty percent of initially incorporated radioactivity by the leaves of R. vesicarius was in 3-phosphoglycerate. The leaves of S. italica and A. paniculatus fixed most of the radioactivity into the C4 acids malate and aspartate. Sugar phosphates, including 3-phosphoglycerate, were not labelled at all. Our data confirm that, in C4 plants, CO2 is initially fixed through phosphoenolpyruvate carboxylation and thus disprove earlier claims that ribulose bisphosphate can be the primary acceptor of CO2 in a C4 plant. The observations further suggested that aspartate formation during carbon fixation might be favoured by illumination.

Pathways of CO2 Fixation in the CAM Plant Kalanchoe daigremontiana. I Patterns of 14CO2 Fixation in the Light

1974 ◽  
Vol 1 (4) ◽  
pp. 503 ◽  
Author(s):  
CB Osmond ◽  
WG Allaway
Keyword(s):  
Steady State ◽  
Co2 Fixation ◽  
Growth Conditions ◽  
Light Period ◽  
C3 Plant ◽  
Initial Burst ◽  
14Co2 Fixation ◽  
C4 Species ◽  
Dark Fixation ◽  
Night Period

Leaves of K. daigremontiana from plants grown under controlled conditions were exposed to 14CO2 in the light for 15 s followed by a chase in 12CO2. During steady-state photosynthesis in the late light period the pulsechase labelling of photosynthetic intermediates was very similar to that observed in the C3 plant Atriplex patula subsp. hastata. Labelling of C4 acids and the distribution of 14C within [14C]malate isolated from leaves of K. daigremontiana in these experiments suggest that these acids arise by a secondary carboxylation of labelled phosphoenolpyruvate. During the initial burst of photosynthesis following the night period, pulse-chase labelling of photosynthetic intermediates was quite similar to that observed in A. spongiosa, a C4 species. Degradation of labelled malate suggests that the C4 acids are formed largely by the primary carboxylation of phosphoenolpyruvate during the initial burst of photosynthesis and that these intermediates mix with the pool of malate formed in previous dark fixation. Growth conditions which substantially alter the proportion of CO2 fixed during the clay and night did not alter the pulse-chase behaviour of photosynthetic intermediates.

Effect of Salinity on Photosynthetic 14CO2 Fixation and Amino Acid Pools of Bellerochea yucatanensis (v. Stosch) and Thalassiosira rotula (Meunier)

1985 ◽  
Vol 40 (7-8) ◽  
pp. 527-530
Author(s):  
Günter Döhler ◽  
Joachim Zink
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Marine Diatoms ◽  
14Co2 Fixation ◽  
Low Salt ◽  
Photosynthetic Products ◽  
Sugar Phosphates ◽  
Total Amino Acids

Abstract The marine diatoms Bellerochea yucatanensis and Thalassiosira rotula were grown at different salinities (20/25, 35, and 40/45‰ salinity (S), respectively) under normal air (0.035 vol.% CO2). No significant variations in the percentage of gross photosynthetic products (e.g. total amino acids, sugar phosphates) were found as a function of salinity during growth. The bulk of the soluble 14C-radioactivity was detected in amino acids. 14C-labelling of glutamine increased markedly with salinity. Low salt - grown algae are characterized by enhanced amino acid pools, mainly of aspartic acid, asparagine and glutamine. It was found that the tested amino acids are not involved in osmoregulation.

Regulation of Chloramphenicol Synthesis in Streptomyces sp. 3022a. 3-Deoxy-D-arabino-heptulosonate 7-Phosphate Synthetase

1971 ◽  
Vol 49 (4) ◽  
pp. 448-455 ◽  
Author(s):  
D. A. Lowe ◽  
D. W. S. Westlake
Keyword(s):  
Enzyme Activity ◽  
Shikimic Acid ◽  
Aromatic Amino Acids ◽  
Product Inhibition ◽  
Enzyme Synthesis ◽  
Synthetase Activity ◽  
Shikimic Acid Pathway ◽  
Sugar Phosphates ◽  
Acid Pathway ◽  
Single Enzyme

The repression and end-product inhibition of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthetase were studied in a chloramphenicol-producing Streptomycetes. Synthesis of DAHP synthetase was repressed by p-hydroxybenzoate, and enzyme activity was inhibited competitively by sugar phosphates, especially D-ribose 5-phosphate. The presence of chloramphenicol, aromatic amino acids, or shikimic acid pathway intermediates did not repress enzyme synthesis nor inhibit enzyme activity. Chloramphenicol production by growing cultures was not affected by the intermediates or end products of the shikimic acid pathway nor by the repression of DAHP synthetase. Purification of DAHP synthetase activity indicated the presence of a single enzyme protein with a molecular weight of 88 000.

Effects of ozone on 14CO2 fixation patterns in pine

1973 ◽  
Vol 51 (9) ◽  
pp. 1573-1578 ◽  
Author(s):  
Thomas G. Wilkinson ◽  
Robert L. Barnes
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Soluble Sugars ◽  
Pinus Strobus ◽  
Relative Activity ◽  
Ozone Treatment ◽  
White Pine ◽  
14Co2 Fixation ◽  
Sugar Phosphates

Seedlings of white pine (Pinus strobus L.) and detached shoots of white and loblolly (P. taeda L.) pines were exposed to various concentrations of ozone either before or during photosynthetic fixation of 14CO2. The major changes in distribution of 14C as a result of ozone treatment were (1) a reduction of relative activity in soluble sugars; (2) an increase in activity in sugar phosphates; and (3) an increase in activity in free amino acids, especially alanine. Significant differences in 14C fixation patterns were observed at ozone concentrations as low as 10 pphm (parts per hundred million), and during 14CO2 fixation times as short as 10 min. However, other combinations of treatment levels and times did not always result in statistically significant effects.

Photosynthesis in the Aquatic MacrophyteEgevia densa. I. 14CO2 Fixation at Natural CO2 Concentrations

1977 ◽  
Vol 4 (2) ◽  
pp. 169 ◽  
Author(s):  
JA Browse ◽  
FI Dromgoole ◽  
JMA Brown
Keyword(s):  
Time Course ◽  
Calvin Cycle ◽  
High Rate ◽  
Previous Suggestion ◽  
Fixation Rate ◽  
14Co2 Fixation ◽  
Co2 Concentrations ◽  
Phosphoglyceric Acid ◽  
Sugar Phosphates ◽  
Inorganic Carbon Concentration

In *14C time-course and pulse-chase experiments, the photosynthetic fixation rate for Egeria densa Planch. was about 19 �mol C (g dry wt)-1 min-1 (13.7 mg C (g dry wt)-1 h-1) at a total inorganic carbon concentration of 1.0 x 10-3 M, pH 6.8 and 75-80% light saturation. At this high rate, under conditions closely approximating those of plants in the field, 14C distribution into 3-phosphoglyceric acid, sugar phosphates and sucrose indicates that the Calvin cycle is the primary carboxylation mechanism and responsible for over 90% of the 14C initially incorporated. Malate accounts for only 5 % of the initial 14CO2 fixation and is not actively further metabolized. Additional label from Calvin cycle intermediates enters malate during the cold chase treatment. It is suggested that the predominant 14C fixation into malic acid, noted in previous reports on Hydrocharitacean species, may be due to very low experimental CO2 concentrations and a consequent suppression of the Calvin cycle activity. Compounds of the glycollate pathway were detected in sufficient quantities to give some support to the previous suggestion of photorespiratory activity in Egeria.

Stomatal Metabolism: Carbon Dioxide Fixation in Attached and Detached Epidermis of Commelina

1978 ◽  
Vol 5 (6) ◽  
pp. 767
Author(s):  
C.M Wilmer ◽  
N Thorpe ◽  
J.C Rutter ◽  
F.L Milthorpe
Keyword(s):  
Carbon Dioxide ◽  
Tca Cycle ◽  
Carbon Dioxide Fixation ◽  
Reverse Direction ◽  
Gaseous Exchange ◽  
14Co2 Fixation ◽  
Fixation Pattern ◽  
The Difference ◽  
Sugar Phosphates ◽  
Tca Cycle Intermediates

Rates of accumulation of radioactivity and the nature of 14CO2 fixation products were measured in mesophyll, attached epidermis and detached epidermis of Commelina cyanea and C. communis. In the illuminated detached epidermis of C. cyanea, most of the fixation products were malate and aspartate (in almost equal proportions), with small amounts of sugars, sugar phosphates, serine, glycine, alanine and TCA cycle intermediates. In that of C. communis there was a smaller proportion of aspartate and a higher proportion of sugars, glutamate and tricarboxylic acids. The much higher rates of accumulation of labelled fixation products in attached epidermis of C. cyanea can in part be attributed to glycine, serine and alanine, which appear to be imported from the mesophyll very shortly after the leaf is first exposed to 14CO2. Over longer periods of time, labelled sugars contributed an appreciable and increasing proportion. In C. communis, after 15-30 min, most of the difference between attached and detached epidermis was attributable to the presence of labelled sugars. The fixation pattern in the mesophyll of these species was typical of C*3-type photosynthesis. Autoradiographs of detached epidermis showed that the label was predominantly in stomata while those of attached epidermis showed more label in stomata than elsewhere after 1 min and they were uniformly labelled after 30 min. These findings suggest that metabolites are translocated from the mesophyll to the epidermis fairly readily. There is probably flow in the reverse direction as well as gaseous exchange of 14C between these tissues.

Light-induced formation of enzymes of the C4-dicarboxylic acid pathway of photosynthesis in detached leaves

1970 ◽  
Vol 9 (3) ◽  
pp. 521-532 ◽  
Author(s):  
D. Graham ◽  
M.D. Hatch ◽  
C.R. Slack ◽  
Robert M. Smillie
Keyword(s):  
Dicarboxylic Acid ◽  
Detached Leaves ◽  
Acid Pathway

Expression patterns of cytoplasmic pyruvate, orthophosphate dikinase of rice (C3) and maize (C4) in a C3 plant, rice

2000 ◽  
Vol 27 (4) ◽  
pp. 343 ◽  
Author(s):  
Mika Nomura ◽  
Naoki Sentoku ◽  
Shigeyuki Tajima ◽  
Makoto Matsuoka
Keyword(s):  
Expression Patterns ◽  
Gus Expression ◽  
C4 Plants ◽  
C3 And C4 Plants ◽  
C3 Plant ◽  
Pyruvate Orthophosphate Dikinase ◽  
Gus Reporter ◽  
Orthophosphate Dikinase ◽  
Organ Specific ◽  
Specific Localization

Two types of mRNAs are transcribed from the C4-type pyruvate, orthophosphate dikinase gene (Pdk) with different sizes, which encode chloroplastic and cytoplasmic forms of the enzyme. The two transcripts are pro duced by two independent promoters and this unusual dual promoter system is also found in the C4-like Pdk gene of the C3 plant, rice. In order to elucidate the expression pattern of the cytoplasmic transcript from the maize C4-type and rice C4-like Pdk genes, we have produced chimeric constructs with the ß-glucuronidase (GUS) reporter gene under the control of the cytoplasmic promoters and introduced the constructs into rice. Both cytoplasmic promoters directed GUS expression in non-photosynthetic organs, such as endosperm and roots, in transgenic rice plants, while expression was low in photosynthetic organs. These results indicate that the organ-specific localization of the cyto-plasmic enzyme is similar in C3 and C4 plants. The results also suggest the possibility that the cytoplasmic enzyme has a similar function(s) in non-photosynthetic organs both in C3 and C4 plants.

14CO2-Fixation in Marine Algae with Special Reference to the Dark-Fixation in Brown Algae

1972 ◽  
Vol 15 (3) ◽  
Author(s):  
HISAYOSHI AKAGAWA ◽  
TOMOYOSHI IKAWA ◽  
KAZUTOSI NISIZAWA
Keyword(s):  
Special Reference ◽  
Brown Algae ◽  
Marine Algae ◽  
14Co2 Fixation ◽  
Dark Fixation
Sign in / Sign up

Export Citation Format

Share Document