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1.
Two sites for the β-oxidation of fatty acids in avocado ( Persea americana L.) mesocarp exist. One site is the microbody, the other the mitochondrion. It is apparent that the mitochondrial membrane barrier, which remains intact after sucrose density gradient centrifugation, prevents rapid access of acyl CoA substrates to matrix β-oxidation sites. Thus, intact mitochondria showed little β-oxidation enzyme activity. Rupturing of the mitochondrial membrane allowed rapid access of the acyl CoA substrates to matrix sites. Consequently, in ruptured mitochondria, high O 2-oxidation enzyme activities were measured. O 2 uptake studies further distinguished the two organellar sites of β-oxidation. During palmitoyl CoA oxidation, O 2 uptake was reduced by catalase and increased by KCN in the microbodies, whilst mitochondrial O 2 uptake was unaffected by catalase and reduced by KCN. This reflected the differing fates of FADH 2, produced during the first β-oxidation step, in the two organelles. In addition, only the mitochondrial β-oxidation of fatty acids was carnitine-dependent. 相似文献
2.
In phosphorylating mitochondria, isolated in 0.25 M sucrose and suspended in a glycylglycine-KC1 medium at pH 7.4, the N-methyl group of sarcosine is oxidized to formaldehyde, formate, and CO 2. The initial rate of O 2 uptake in this system is only about half as great as with phosphate-washed mitochondria, in which the N-methyl carbon is oxidized only to the level of “active formaldehyde” and can be recovered as serine-β-carbon and/or formaldehyde. In the glycylglycine-KC1 medium, the O 2 uptake with sarcosine occurs in a biphasic manner and the initial slower rate can be extended by the addition of Mg 2+, and ADP, AMP, or ATP. O 2 uptake is similarly restrained by ADP in mitochondria buffered with imidazole or pyrophosphate. The ADP effect is not observed in the presence of dinitrophenol. The patterns of O 2 uptake obtained with ADP in these various media are not altered when the oxidation of the formaldehyde, derived from the N-methyl group, is suppressed by the addition of either semicarbazide or rotenone. With dimethylglycine, another component of the “1-C cycle”, the initial rate of oxidation in glycylglycine or imidazole is enhanced by ADP rather than being decreased. These results together with appropriate coenzyme analyses suggest that reactions of “one carbon compounds” can provide sensitive markers for assessing compartition of cofactors such as the pyridine nucleotides, flavins, and folates in the mitochondrial matrix. 相似文献
3.
It is reported here on random acceleration molecular dynamics (RAMD) simulations with the 2GF3 bacterial monomeric sarcosine oxidase (MSOX), O 2, and furoic acid in place of sarcosine, solvated by TIP3 H 2O in a periodic box. An external tiny force, acting randomly on O 2, accelerated its relocation, from the center of activation between residue K265 and the si face of the flavin ring of the flavin adenine dinucleotide cofactor, to the surrounding solvent. Only three of the four O 2 gates previously described for this system along a composite method technique were identified, while two more major O 2 gates were found. The RAMD simulations also revealed that the same gate can be reached by O 2 along different pathways, often involving traps for O 2. Both the residence time of O 2 in the traps, and the total trajectory time for O 2 getting to the solvent, could be evaluated. The new quick pathways discovered here suggest that O 2 exploits all nearby interstices created by the thermal fluctuations of the protein, not having necessarily to look for the permanent large channel used for uptake of the FADH cofactor. To this regard, MSOX resembles closely KijD3 N‐oxygenase. These observations solicit experimental substantiation, in a long term aim at discovering whether gates and pathways for the small gaseous ligands inside the proteins are under Darwinian functional evolution or merely stochastic control operates. 相似文献
4.
Photosynthetic O 2 production and photorespiratory O 2 uptake were measured using isotopic techniques, in the C 3 species Hirschfeldia incana Lowe., Helianthus annuus L., and Phaseolus vulgaris L. At high CO 2 and normal O 2, O 2 production increased linearly with light intensity. At low O 2 or low CO 2, O 2 production was suppressed, indicating that increased concentrations of both O 2 and CO 2 can stimulate O 2 production. At the CO 2 compensation point, O 2 uptake equaled O 2 production over a wide range of O 2 concentrations. O 2 uptake increased with light intensity and O 2 concentration. At low light intensities, O 2 uptake was suppressed by increased CO 2 concentrations so that O 2 uptake at 1,000 microliters per liter CO 2 was 28 to 35% of the uptake at the CO 2 compensation point. At high light intensities, O 2 uptake was stimulated by low concentrations of CO 2 and suppressed by higher concentrations of CO 2. O 2 uptake at high light intensity and 1000 microliters per liter CO 2 was 75% or more of the rate of O 2 uptake at the compensation point. The response of O 2 uptake to light intensity extrapolated to zero in darkness, suggesting that O 2 uptake via dark respiration may be suppressed in the light. The response of O 2 uptake to O 2 concentration saturated at about 30% O 2 in high light and at a lower O 2 concentration in low light. O 2 uptake was also observed with the C 4 plant Amaranthus edulis; the rate of uptake at the CO 2 compensation point was 20% of that observed at the same light intensity with the C 3 species, and this rate was not influenced by the CO 2 concentration. The results are discussed and interpreted in terms of the ribulose-1,5-bisphosphate oxygenase reaction, the associated metabolism of the photorespiratory pathway, and direct photosynthetic reduction of O 2. 相似文献
5.
Summary Simultaneous measurements of ventilatory frequency, tidal volume, O 2 uptake, CO 2 output and cardiac frequency were made in the diamondback water snake, Natrix rhombifera while breathing hypoxic (15% to 5% O 2 in N 2) or hypercarbic (2% to 10% CO 2 and 21% O 2 in N 2) gases. The snakes responded to hypoxia by increasing tidal volume and decreasing ventilatory frequency resulting in little change in ventilation (50% increase at 5% inspired O 2), or O 2 uptake and only a light increase in CO 2 output. Hypercarbia to 4.2% inspired CO 2 resulted in a slight hyperventilation but ventilation was depressed at 6.3% inspired CO 2 and became erratic at higher concentrations. The resting rate of O 2 uptake was maintained throughout hypercapnia. Heart rate increased during hypoxia and decreased during hypercapnia. Cutaneous O 2 uptake increased during extreme hypoxia (5% inspired O 2) and cutaneous CO 2 output increased during hypercapnia, probably due to changes in the body-to-ambient gas gradients (Crawford and Schultetus, 1970). Both pulmonary oxygen uptake and ventilation were dramatically increased immediately following 10–15 min experimental dives. The increased ventilation was achieved primarily through an increased tidal volume. 相似文献
6.
In this work, two protein systems, Kij3D? FMN? AKM? O 2 and Kij3D? FMN? O 2, made of KijD3 N‐oxygenase, flavin mononucleotide (FMN) cofactor, dTDP‐3‐amino‐2,3,6‐trideoxy‐4‐keto‐3‐methyl‐D ‐glucose (AKM) substrate, and dioxygen (O 2), have been assembled by adding a molecule of O 2, and removing (or not) AKM, to crystal data for the Kij3D? FMN? AKM complex. Egress of AKM and O 2 from these systems was then investigated by applying a tiny external random force, in turn, to their center of mass in the course of molecular dynamics in explicit H 2O. It turned out that the wide AKM channel, even when emptied, does not constitute the main route for O 2 egress. Other routes appear to be also viable, while various binding pockets (BPs) outside the active center are prone to trap O 2. By reversing the reasoning, these can also be considered as routes for uptake of O 2 by the protein, before or after AKM uptake, while BPs may serve as reservoirs of O 2. This shows that the small molecule O 2 is capable of permeating the protein by exploiting all nearby interstices that are created on thermal fluctuations of the protein, rather than having necessarily to look for farther, permanent channels. 相似文献
7.
Concurrent O 2 evolution, O 2 uptake, and CO 2 uptake by illuminated maize ( Zea mays) leaves were measured using 13CO 2 and 18O 2. Considerable O 2 uptake occurred during active photosynthesis. At CO 2 compensation, O 2 uptake increased. Associated with this increase was a decrease in O 2 release such that a stoichiometric exchange of O 2 occurred. The rate of O 2 exchange at CO 2 compensation was directly related to O 2 concentration in the atmosphere at least up to 8% (v/v). 相似文献
8.
The enhanced dark CO 2 uptake after a preillumination period under varying O 2 concentrations has been measured with maize, a C 4 plant. For comparison the same study has been conducted with tomato, a C 3 plant. Increasing the O 2 concentration during preillumination inhibits by 70% the subsequent dark CO 2 uptake in tomato but stimulates 2-fold this CO 2 uptake in maize. The O 2 enhancement of CO 2 uptake in maize is due to the enhancement of malate and aspartate synthesis. The percentages of radioactivity incorporated in the C-4 of malate and aspartate vary from 74 to 87% when O 2 concentration during preillumination is increased from 0 to 100%. 相似文献
9.
An in vitro O 2 assay was used to measure early response of wheat ( Triticum aestivum L.) etioplasts to light. A transient photoinducible O 2 uptake occurred when dark-grown etioplasts were initially exposed to light. The rate of inducible O 2 consumption was dependent on both the intensity of light and the quantity of organelle protein present. Higher light intensities resulted in greater O 2 utilization per minute, and a greater quantity of organelle protein in the sample resulted in an increased rate of O 2 uptake under the same light intensity conditions. Experiments with various plant tissues as well as with mitochondrial respiratory inhibitors indicated that etioplasts are the organelles responsible for the photoinduced O 2 uptake phenomenon. A preliminary action spectrum study revealed that wavelengths 640 to 680 nm resulted in maximum O 2 uptake. This indicated the presence of an etioplast red light receptor pigment which induces O 2 uptake in etioplasts. 相似文献
10.
Light-dependent O 2 exchange was measured in intact, isolated soybean ( Glycine max. var. Williams) cells using isotopically labeled O 2 and a mass spectrometer. The dependence of O 2 exchange on O 2 and CO 2 was investigated at high light in coupled and uncoupled cells. With coupled cells at high O 2, O 2 evolution followed similar kinetics at high and low CO 2. Steady-state rates of O 2 uptake were insignificant at high CO 2, but progressively increased with decreasing CO 2. At low CO 2, steady-state rates of O 2 uptake were 50% to 70% of the maximum CO 2-supported rates of O 2 evolution. These high rates of O 2 uptake exceeded the maximum rate of O 2 reduction determined in uncoupled cells, suggesting the occurrence of another light-induced O 2-uptake process ( i.e. photorespiration). Rates of O2 exchange in uncoupled cells were half-saturated at 7% to 8% O2. Initial rates (during induction) of O2 exchange in uninhibited cells were also half-saturated at 7% to 8% O2. In contrast, steady-state rates of O2 evolution and O2 uptake (at low CO2) were half-saturated at 18% to 20% O2. O2 uptake was significantly suppressed in the presence of nitrate, suggesting that nitrate and/or nitrite can compete with O2 for photoreductant. These results suggest that two mechanisms (O2 reduction and photorespiration) are responsible for the light-dependent O2 uptake observed in uninhibited cells under CO2-limiting conditions. The relative contribution of each process to the rate of O2 uptake appears to be dependent on the O2 level. At high O2 concentrations (≥40%), photorespiration is the major O2-consuming process. At lower (ambient) O2 concentrations (≤20%), O2 reduction accounts for a significant portion of the total light-dependent O2 uptake. 相似文献
11.
C 4 grasses of the NAD‐ME type ( Astrebla lappacea, Eleusine coracana, Eragrostis superba, Leptochloa dubia, Panicum coloratum, Panicum decompositum) and the NADP‐ME type ( Bothriochloa bladhii, Cenchrus ciliaris, Dichanthium sericeum, Panicum antidotale, Paspalum notatum, Pennisetum alopecuroides, Sorghum bicolor) were used to investigate the role of O 2 as an electron acceptor during C 4 photosynthesis. Mass spectrometric measurements of gross O 2 evolution and uptake were made concurrently with measurements of net CO 2 uptake and chlorophyll fluorescence at different irradiances and leaf temperatures of 30 and 40 °C. In all C 4 grasses gross O 2 uptake increased with increasing irradiance at very high CO 2 partial pressures ( pCO 2) and was on average 18% of gross O 2 evolution. Gross O 2 uptake at high irradiance and high pCO 2 was on average 3.8 times greater than gross O 2 uptake in the dark. Furthermore, gross O 2 uptake in the light increased with O 2 concentration at both high CO 2 and the compensation point, whereas gross O 2 uptake in the dark was insensitive to O 2 concentration. This suggests that a significant amount of O 2 uptake may be associated with the Mehler reaction, and that the Mehler reaction varies with irradiance and O 2 concentration. O 2 exchange characteristics at high pCO 2 were similar for NAD‐ME and NADP‐ME species. NAD‐ME species had significantly greater O 2 uptake and evolution at the compensation point particularly at low irradiance compared to NADP‐ME species, which could be related to different rates of photorespiratory O 2 uptake. There was a good correlation between electron transport rates estimated from chlorophyll fluorescence and gross O 2 evolution at high light and high pCO 2. 相似文献
12.
A practical method for predicting the dissolved oxygen (DO) profile in a stream receiving biodegradable waste is presented. In this method the BOD (accumulated O 2 uptake) curve is obtained using an open jug technique. The accumulated O 2 uptake curve thus developed is employed in numerical integration with the physical reaeration data for the receiving stream to predict the DO profile in the stream. In the present study, the method was examined using 10-liter open jar reactors to obtain the O 2 uptake curves, and the receiving stream was a 670-liter simulated stream apparatus which has been employed in previous studies on stream reaeration. The method was found to provide a fairly good prediction of the actual dissolved oxygen profile observed in the receiving stream. The effect of the reaeration constant, K 2 )agitation effect(, on the kinetics of O 2 uptake was also investigated and it was found that increased agitation (higher K 2 value) caused some increase in the accumulated oxygen uptake (BOD) curve with most of the increase coming after the so-called “plateau” area in the O 2 uptake curve, i.e., in the general case, after the low point along the DO sag curve. 相似文献
13.
A mass spectrometric 16O 2/ 18O 2-isotope technique was used to analyse the rates of gross O 2 evolution, net O 2 evolution and gross O 2 uptake in relation to photon fluence rate by Dunaliella tertiolecta adapted to 0.5, 1.0, 1.5, 2.0 and 2.5 M NaCl at 25°C and pH 7.0.At concentrations of dissolved inorganic carbon saturating for photosynthesis (200 M) gross O 2 evolution and net O 2 evolution increased with increasing salinity as well as with photon fluence rate. Light compensation was also enhanced with increased salinities. Light saturation of net O 2 evolution was reached at about 1000 mol m -2s -1 for all salt concentrations tested. Gross O 2 uptake in the light was increased in relation to the NaCl concentration but it was decreased with increasing photon fluence rate for almost all salinities, although an enhanced flow of light generated electrons was simultaneously observed. In addition, a comparison between gross O 2 uptake at 1000 mol photons m -2s -1, dark respiration before illumination and immediately after darkening of each experiment showed that gross O 2 uptake in the light paralleled but was lower than mitochondrial O 2 consumption in the dark.From these results it is suggested that O 2 uptake by Dunaliella tertiolecta in the light is mainly influenced by mitochondrial O 2 uptake. Therefore, it appears that the light dependent inhibition of gross O 2 uptake is caused by a reduction in mitochondrial O 2 consumption by light.Abbreviations DCMU
3-(3, 4-dichlorophenyl)-1, 1-dimethylurea
- DHAP
dihydroxy-acetonephosphate
- DIC
dissolved inorganic carbon
- DR a
rate of dark respiration immediately after illumination
- DR b
rate of dark respiration before illumination
- E 0
rate of gross oxygen evolution in the light
- NET
rate of net oxygen evolution in the light
- PFR
photon fluence rate
- RubP
rubulose-1,5-bisphosphate
- SHAM
salicyl hydroxamic acid
- U 0
rate of gross oxygen uptake in the light 相似文献
14.
Summary Effects of temperature acclimation (5 or 25 °C for 2–4 weeks) and metamorphosis on oxygen uptake, acid-base balance and blood-O 2 affinity have been investigated in Ambystoma tigrinum. The results differ from previous studies in three ways. (1) The transition from gilled to gill-less adults had no effect on the O 2 affinity of blood. (2) Cold acclimation increased blood O 2 affinity in neotenes and had no effect in adults. (3) O 2 uptake increased, rather than decreased, after acclimation to a higher temperature. The results resemble previous studies also in three ways. (1) O 2 uptake increased with the transition from gilled-neotenes to gill-less adults as did the dependence on air-breathing. (2) Metamorphosis resulted in CO 2 retention and a fall in arterial pH. (3) The temperature coefficient of blood pH was about –0.014 dpH/ dT in vivo and in vitro. The physiological significance of the results is discussed with respect to the natural history, modes of breathing, and dependance on aerial respiration of Ambystoma tigrinum. 相似文献
15.
Auxin-mediated elongation growth of maize coleoptile segments is inhibited by reducing the O 2 concentration in the incubation medium to GT 100 μmol . 1 ?1. The half-maximal elongation rate is reached at 40 μmol . 1 ?1 O 2, i.e. about two orders of magnitude higher than with mitochondrial respiration. O 2 uptake of the segments measured under similar conditions with an O 2 electrode shows a very similar dependence on O 2 concentration. Auxin increases O 2 uptake by 5–10% when it induces growth. About 40% of the O 2 uptake is insensitive to inhibition by KCN. Auxin has no effect on O 2 uptake in the presence of KCN. The possibility that auxin-mediated elongation growth depends on a KCN-sensitive oxidative process, other than cytochrome c oxidase-catalyzed respiration, is discussed. 相似文献
16.
The oxyhydrogen reaction in the presence and absence of CO 2 was studied in H 2-adapted Scenedesmus obliquus by monitoring the initial rates of H 2, O 2, and 14CO 2 uptake and the effect of inhibitors on these rates with gas-sensing electrodes and isotopic techniques. In the presence of 0.02 atmosphere O 2, the pH 2 was varied from 0 to 1 atmosphere. Whereas the rate of O 2 uptake increased by only 30%, the rate of H 2 uptake increased severalfold over the range of pH 2 values. At 0.1 atmosphere H 2 and 0.02 atmosphere O 2, rates for H 2 and O 2 uptake were between 15 and 25 micromoles per milligram chlorophyll per hour. As the pH 2 was changed from 0 to 1 atmosphere, the quotient H 2:O 2 changed from 0 to roughly 2. This change may reflect the competition between H 2 and the endogenous respiratory electron donors. Respiration in the presence of glucose and acetate was also competitive with H 2 uptake. KCN inhibited equally respiration (O 2 uptake in the absence of H 2) and the oxyhydrogen reaction in the presence and absence of CO 2. The uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone accelerated the rate of respiration and the oxyhydrogen reaction to a similar extent. It was concluded that the oxyhydrogen reaction both in the presence and absence of CO 2 has properties in common with components of respiration and photosynthesis. Participation of these two processes in the oxyhydrogen reaction would require a closely linked shuttle between mitochondrion and chloroplast. 相似文献
17.
The uptake and degradation of atrazine (ATR) by rice seedlings ( Oryza sativa L.) was investigated with and without arsenate and phosphate nutrient in the cultured solution over a period of 48 h. The hydrogen peroxide (H 2O 2) contents in plants under different treatments were measured to evaluate the oxidative stress of the plant cell and its influence on the plant uptake and degradation of ATR. Results indicated that the ATR levels and main degradation products, deethylatrazine (DEA) and deisopropylatrazine (DIA), in plants varied significantly in different treatments. Added arsenate in solution increased the level of DEA and the ratios of DEA to the total (ATR, DEA, and DIA) in roots, while it either increased or decreased the H 2O 2 content in roots. Added arsenate increased the ratios of degradation products to the total in shoots, which corresponded to the 110%–285% increase of the H 2O 2 content. In phosphate-deficient systems, the H 2O 2 contents in shoots increased significantly, especially when exposed to a low level of ATR while the ratios of DIA and DEA to the total in shoots increased. The oxidative stress in rice seedlings induced by arsenic coexisting with ATR and by phosphate deficiency affected the plant uptake and degradation of ATR. 相似文献
18.
Cell survival and death-inducing signals are tightly associated with each other, and the decision as to whether a cell survives or dies is determined by controlling the relationship between these signals. However, the mechanism underlying the reciprocal regulation of such signals remains unclear. In this study, we reveal a functional association between PDK1 (3-phosphoinositide-dependent protein kinase 1), a critical mediator of cell survival, and ASK1 (apoptosis signal-regulating kinase 1), an apoptotic stress-activated MAPKKK. The physical association between PDK1 and ASK1 is mediated through the pleckstrin homology domain of PDK1 and the C-terminal regulatory domain of ASK1 and is decreased by ASK1-activating stimuli, such as H 2O 2, tumor necrosis factor α, thapsigargin, and ionomycin, as well as insulin, a PDK1 stimulator. Wild-type PDK1, but not kinase-dead PDK1, negatively regulates ASK1 activity by phosphorylating Ser 967, a binding site for 14-3-3 protein, on ASK1. PDK1 functionally suppresses ASK1-mediated AP-1 transactivation and H 2O 2-mediated apoptosis in a kinase-dependent manner. On the other hand, ASK1 has been shown to inhibit PDK1 functions, including PDK1-mediated regulation of apoptosis and cell growth, by phosphorylating PDK1 at Ser 394 and Ser 398, indicating that these putative phosphorylation sites are involved in the negative regulation of PDK1 activity. These results provide evidence that PDK1 and ASK1 directly interact and phosphorylate each other and act as negative regulators of their respective kinases in resting cells. 相似文献
19.
Abstract: Spontaneous oxygen consumption by 5,6- and 5,7-DHT (dihydroxytryptamine), related indoleethylamines, and 6-hydroxydopamine and oxygen consumption by these compounds in the presence of rat liver mitochondria were measured by the polarographic oxygen electrode technique. 5,6- and 5,7-DHT react with oxygen at very different rates (2.7 nmol O 2/min and 33.4 nmol O 2/min, respectively) when incubated in buffer, pH 7.2, at a concentration of 1 mm and with different kínetic characteristics. While the oxidation of 5,7-DHT obeys a reaction of second-order type, the oxidation of 5,6-DHT is more complex and characterized by autocatalytic promotion. Coloured quinoidal oxidation products appeared during the degradation of both indoleamines. Glutathione, ascorbate, dithiothreitol, cysteine, albumin, and superoxide dismutase partially prevented 5,6- and 5,7-DHT from oxidative destruction. Catalase saved oxygen only in the case of 5,6-DHT by recycling of O 2 released from near-stoichiometrically formed H 2O 2 during oxidation of 5,6-DHT: 5,7-DHT did not generate H 2O 2 in measurable amounts. Oxygen consumption rates of 5,6- and 5,7-DHT were enhanced after addition of rat liver mitochondria to the incubation medium; this resulted in an accelerated formation of quinoidal products. This stimulatory effect on the oxidation rates of both 5,6- and 5,7-DHT was blocked by cyanide, but not rotenone, and was abolished by boiling of the mitochondria fraction. The observed increase in oxygen consumption in the presence of mitochondria was found not to be influenced by monoamine oxidase-dependent deamination of 5,6- and 5,7-DHT. It is postulated that 5,6- and 5,7-DHT are capable of participating in the electron transfer of the mitochondrial respiration chain beyond complex III. Results obtained in determinations of ADP:0 ratios in respiratory control experiments exclude a possible interference of 5,6-DHT, 5,7-DHT, and 6-OH-DA with phosphorylating sites. During the activated state of respiration, no signs of electron transfer inhibition by 5,6- and 5,7-DHT were detectable. A comparison and evaluation of the autoxidation rates of various hydroxylated indoleethylamines, of their affinity to the 5-HT transport sites, and their neurotoxic potency in vivo reveals that interaction of these compounds with oxygen at restricted reaction velocity is a prerequisite for efficient toxicity in monoaminergic neurons following active accumulation in these neurons via the high-affinity uptake systems. 相似文献
20.
Unidirectional O 2 fluxes were measured with 18O 2 in a whole plant of wheat cultivated in a controlled environment. At 2 or 21% O 2, O 2 uptake was maximum at 60 microliters per liter CO 2. At lower CO 2 concentrations, it was strongly inhibited, as was photosynthetic O 2 evolution. At 2% O 2, there remained a substantial O 2 uptake, even at high CO 2 level; the O 2 evolution was inhibited at CO 2 concentrations under 330 microliters per liter. The O 2 uptake increased linearly with light intensity, starting from the level of dark respiration. No saturation was observed at high light intensities. No significant change in the gas-exchange patterns occurred during a long period of the plant life. An adaptation to low light intensities was observed after 3 hours illumination. These results are interpreted in relation to the functioning of the photosynthetic apparatus and point to a regulation by the electron acceptors and a specific action of CO 2. The behavior of the O 2 uptake and the study of the CO 2 compensation point seem to indicate the persistence of mitochondrial respiration during photosynthesis. 相似文献
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