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41.
The 13C-nuclear magnetic resonance (NMR) spectra of chlorophyll a formed in dark-grown Scenedesmus obliquus (Turp.) Kützing in the presence of [1-13C]glutamate, [2-13C]- and [1-13C]glycineshowed that the 13C of glutamate was specifically incorporated into the eight-carbon atoms in the tetrapyrrole macrocycles derived from C-5 of 5-aminolevulinic acid (ALA), while the C-2 of glycine was only incorporated into the methyl carbon of the methoxycarbonyl group attached to the isocyclic ring of chlorophyll a. No specific enrichment of these nine carbon atoms was observed in the spectrum of chlorophyll a formed in the presence of [1-13C]-glycine. These labeling patterns provide evidence for the operation of the C5-pathway and against the operation of the ALA synthase pathway for chlorophyll formation in darkness. 相似文献
42.
To optimize the aeration conditions for microalgal biomass production in a vertical flat-plate photobioreactor (VFPP), the effect of the aeration rate on biomass productivity was investigated under given conditions. Air enriched with 5% or 10% (v/v) CO(2) was supplied for the investigation at rates of 0.025-1 vvm. The CO(2) utilization efficiency, change of pH in the medium, and the optimum aeration rate were determined by evaluating biomass productivity. To investigate the VFPP mass transfer characteristics, the overall volumetric mass transfer coefficient, k(L)a, was evaluated for several different flat-plate sizes. Increasing the height of the VFPP could improve both the mass transfer of CO(2) and the illumination conditions, so this appeared to be a good method for scaling up. Based on a comparison of the k(L)a value at the optimum aeration rate with previously reported results, it was confirmed that the range of CO(2) concentration used in the experiments was cost-effective for mass culture. 相似文献
43.
Hideaki Miyashita Hisato Ikemoto Norihide Kurano Shigetoh Miyachi Mitsuo Chihara 《Journal of phycology》2003,39(6):1247-1253
The phylogenetic position of an oxygenic photosynthetic prokaryote containing chl d as a major pigment, which have been tentatively named “Acaryochloris marina,” was analyzed using small subunit rDNA sequences. Phylogenetic relationships inferred among A. marina, selected strains from the Cyanobacteria, and plastids showed that A. marina was within the cyanobacterial radiation. The A. marina lineage diverged independently from other phylogenetic subgroups of the Cyanobacteria. No organism was found to be identical or related closely to A. marina by a similarity search and phylogenetic analysis. Based on these results, in addition to the reported characteristics of the cell morphology, pigment composition, and photosynthesis, a new taxon, Acaryochloris marina Miyashita et Chihara gen. et sp. nov., is formally proposed for the oxy‐genic photosynthetic prokaryote. 相似文献
44.
Maribel L. Dionisio-Sese Atsuhiro Shimada Tadashi Maruyama Shigetoh Miyachi 《Archives of microbiology》1993,159(1):1-5
The prokaryotic algal symbiont of ascidians, Prochloron sp., was found to exhibit carbonic anhydrase activity which is largely associated with the cell surface. This extracellular carbonic anhydrase activity was inhibited, while the intracellular activity was not affected, by chloride or bromide. Acetazolamide and ethoxyzolamide inhibited carbonic anhydrase activity with I50 values of 7×10-4 and 3×10-4M, respectively. These I50 values are similar to those observed for intracellular carbonic anhydrases of Synechococcus sp. PCC7942, Chlamydomonas reinhardii and spinach.Abbreviations AZA
acetazolamide
- CA
carbonic anhydrase
- chl
chlorophyll
- EZA
ethozyzolamide
- I50
concentration of an inhibitor required to cause 50% inhibition
- Rubisco
ribulose-1,5-bisphosphate carboxylase/oxygenase
- U
unit 相似文献
45.
Carbonic Anhydrase of Chlamydomonas: Purification and Studies on its Induction Using Antiserum against Chlamydomonas Carbonic Anhydrase 总被引:2,自引:0,他引:2
Carbonic anhydrase (EC 4.2.1.1
[EC]
; CA) was purified by affinitychromatography from cells of the unicellular green alga Chlamydomonasreinhardtii which had been grown photoautotrophically in ordinaryair. Antiserum raised in rabbit against this purified CA crossreactedwith Chlamydomonas CA but not with spinach leaf CA nor bovineerythrocyte CA. When the CO2 concentration provided to the algalcells was decreased from 4% to the ordinary air level (0.04%),CA activity and the content of CA protein determined by theimmunodiffusion test showed parallel increases. In contrast,when the CO2 concentration was raised from air level to 4% CO2CA activity and its content expressed on the basis of culturevolume remained rather constant. These results indicate thatsynthesis of the CA protein is induced when the CO2 concentrationis lowered from 4 to 0.04% during algal growth. On the otherhand, the synthesis of CA stops when CO2 concentration is raisedfrom air level to 4%. (Received June 30, 1984; Accepted October 8, 1984) 相似文献
46.
- The capacity of light-enhanced dark fixation of 14CO2 from theambient atmosphere decayed following time-course characteristicsof a first-order reaction (half-life, 12 min). The levelof phosphoenolpyruvate in maize leaves under CO2-free air didnot decrease in the dark subsequent to preillumination. Theseresults indicate that phosphoenolpyruvate carboxylase is activatedin light and quickly inactivated in the following darkness.
- Removal of oxygen from the atmosphere did not exert any effecton the products of light-enhanced dark fixation of 14CO2 providedfrom the atmosphere, the major labeled compounds being malateand aspartate. This confirms that the transfer of carboxyl carbonof C4-acids to form 3-phosphoglycerate is light-dependent.
- WhenNaH14CO3 solution was vacuum-infiltrated through vasculartissuesof maize leaves, the main initial photosynthetic 14CO2fixationproducts were phosphate esters. This indicates thatby thistechnique, 14CO2 could be directly provided to the bundlesheathcells, and was fixed via the reductive pentose phosphatecycle.On the other hand, the main initial 14CO2-fixation productswere malate and aspartate even when 14CO2 was provided throughvascular tissues in the dark immediately following preillumination.The possible regulatory mechanisms underlying the above findingsare discussed.
47.
Reports in the 1970s from several laboratories revealed that the affinity of photosynthetic machinery for dissolved inorganic
carbon (DIC) was greatly increased when unicellular green microalgae were transferred from high to low-CO2 conditions. This increase was due to the induction of carbonic anhydrase (CA) and the active transport of CO2 and/or HCO3
− which increased the internal DIC concentration. The feature is referred to as the `CO2-concentrating mechanism (CCM)'. It was revealed that CA facilitates the supply of DIC from outside to inside the algal cells.
It was also found that the active species of DIC absorbed by the algal cells and chloroplasts were CO2 and/or HCO3
−, depending on the species. In the 1990s, gene technology started to throw light on the molecular aspects of CCM and identified
the genes involved. The identification of the active HCO3
− transporter, of the molecules functioning for the energization of cyanobacteria and of CAs with different cellular localizations
in eukaryotes are examples of such successes. The first X-ray structural analysis of CA in a photosynthetic organism was carried
out with a red alga. The results showed that the red alga possessed a homodimeric β-type of CA composed of two internally
repeating structures. An increase in the CO2 concentration to several percent results in the loss of CCM and any further increase is often disadvantageous to cellular
growth. It has recently been found that some microalgae and cyanobacteria can grow rapidly even under CO2 concentrations higher than 40%. Studies on the mechanism underlying the resistance to extremely high CO2 concentrations have indicated that only algae that can adopt the state transition in favor of PS I could adapt to and survive
under such conditions. It was concluded that extra ATP produced by enhanced PS I cyclic electron flow is used as an energy
source of H+-transport in extremely high-CO2 conditions. This same state transition has also been observed when high-CO2 cells were transferred to low CO2 conditions, indicating that ATP produced by cyclic electron transfer was necessary to accumulate DIC in low-CO2 conditions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
48.
Functional organization of the photosynthetic apparatus in the unique chlorophyll d-predominating prokaryote, Acaryochloris marina, was studied using polarographic measurements of single-turnover flash yields, action spectra and optical cross sections
for PS-specific reactions. O2 evolution was indicative of PS II activity, while reversible photoinhibition of respiratory O2 uptake under aerobic conditions in the presence of DCMU and H2 photoevolution by anaerobically adapted cells were the indicatives of PS I activity. O2 evolution in the cells upon single-turnover flashes followed the normal S-state cycle with a period-4 oscillation. Analysis
of action spectra for the partial reactions of photosynthesis revealed that: (1) distinct spectral forms of Chl d are nonuniformly distributed between PS I and PS II, e.g. Chl d-695 and Chl d-735 are preferentially located in PS II and PS I, respectively; (2) a minor fraction of Chl a in the cells belongs mostly to PS II; (3) biliproteins transfer excitation energy both to PS II and, with a lower efficiency,
PS I; (4) the efficiency of energy transfer from biliproteins to PS II depends on the light quality growth conditions and
is larger in white light (WL)-grown cells compared to the red light (RL)-grown cells. Content of functional O2 evolving PS II centers decreases 2 times in the RL-grown cells relative to the WL-grown cells, whereas content of competent
PS I centers involved in photoinhibition of respiration remains almost the same in both the cultures. The effective antenna
size of PS I was estimated to be 80–90 Chl d including 3–10 molecules absorbing at 735 nm. The effective optical cross-section of PS II corresponded to 90–100 Chl d and, presumably, 4 Chl a + 2 Pheo a [Mimuro et al. (1999) Biochim Biophys Acta 1412: 37–46]. Optical cross-section measurements indicated that the functional
PS II units of A. marina attach one rod of four hexameric units of biliproteins.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
49.
Illumination with blue light enhanced the production of ammoniaby cells of C. vulgaris 11h, while no such effect was inducedby red light illumination. Addition of ammonia caused increasesin ATP levels and decreases in Pi and ADP levels. When 5 mMNH4Cl was added to phosphorylase and amylase isolated from thecells of C. vulgaris 11h, their activities increased about 515%and 40100%, respectively. (Received June 21, 1986; Accepted December 23, 1986) 相似文献
50.
Microalgal photosynthesis is efficient enough to fix CO2 in both atmosphere and industrially discharged gases, and is a possible future alternative for CO2 reduction. This paper describes physiological responses of microalgal cells to extremely high CO2 concentrations, capability of microalgal cells to fix CO2 at both indoor and outdoor culture experiments, and efforts to establish a culture collection of marine microalgae. Recent researches indicate that microalgae are likely to play a key role in worldwide issues of the coming century. 相似文献