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1821. Chloroplast biogenesis 82: Development of a cell-free system capable of the net synthesis of chlorophyll(ide) b

Creator:
Kolossov, V., Ioannides, I. M., Kulur, S., and Rebeiz, C. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
5-aminolevulinic acid, Cucumis, etiochloroplast, and tetrapyrroles
Language:
Multiple languages
Description:
Recent experimental evidence (see part 80) suggests that the chlorophyll (Chl) b pathway is biosynthetically heterogeneous. The dissection of this biosynthetic heterogeneity requires the availability of a cell-free system capable of the net synthesis of Chl(ide) a and b. The development of such a system is described. and V. Kolossov ... [et al.].
Rights:
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1822. Chloroplast functionality assessment by flow cytometry: case study with pea plants under Paraquat stress

Creator:
Rodriguez, E., Azevedo, R., Costa, A., Serôdio, J., and Santos, C.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, chlorophyll fluorescence, chloroplast, flow cytometry, herbicide, Paraquat, photosynthesis, pulse-amplitude modulation fluorometry, 2, and 58
Language:
Multiple languages
Description:
a1_Photosynthesis is one of the most important processes in plant biology and in the development of new methodologies that allow a better understanding and characterization of the photosynthetic status of organisms, which is invaluable. Flow cytometry (FCM) is an excellent tool for measuring fluorescence and physical proprieties of particles but it has seldom been used in photosynthetic studies and thus the full extent of its potentialities, in this field of research, remains unknown. To determine the suitability of FCM in photosynthesis studies, pea plants were exposed to Paraquat and their status was analyzed during 24 h. FCM was used to evaluate the integrity (volume and internal complexity) and the relative fluorescence intensity (FL) of chloroplasts extracted from those plants. To elucidate which type of information the FL conveys, FL values were correlated with the minimum fluorescence level (F0), maximum fluorescence level (Fm) and maximum photochemical efficiency of PSII (Fv/Fm), obtained by using Pulse-Amplitude-Modulation (PAM) fluorometry. Results indicate that: (1) the biomarkers used to evaluate the structural integrity of the chloroplasts were more sensitive to Paraquat exposure than the ones related to fluorescence; (2) the variation of the chloroplast’s structure, as time progressed, pointed to a swelling and subsequent burst of the chloroplast which, in turn, compromised fluorescence emission; (3) FL presented a high and significant correlation with the Fv/Fm and to a lesser degree with Fm but not with F0; (4) pigment content did not reveal significant changes in response to Paraquat exposure and is in agreement with the proposed model, suggesting that the cause for fluorescence decrease is due to chloroplast disruption., a2_In sum, FCM proved to be an outstanding technique to evaluate chloroplastidal functional and structural status and therefore it should be regarded as a valuable asset in the field of photosynthetic research., E. Rodriguez ... [et al.]., and Obsahuje bibliografii
Rights:
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1823. Chloroplast pigment photobleaching and its effect on low temperature fluorescence spectra of chlorophyll in greening cucumber cotyledons

Creator:
Wieckowski, S. and Waloszek, A.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Effects of high irradiance (HI) treatment on chloroplast pigment bleaching and on low temperature excitation and emission fluorescence spectra were studied in thylakoids isolated from 3- or 24-h greening cucumber cotyledons of etiolated seedlings. Irradiation of thylakoids isolated from 3-h greening seedlings with HI (approx. 3500 pmol m'^ s'*) caused chlorophyll (Chl) and carotenoid (Car) breakdown with the initial rates 3.0 and 4.2 mg m’^ s'*, respectively, whereas these values were 1.3 and 0.8 mg m-^ s'^ respectively, in thylakoids isolated from 24-h greening cotyledons. The photosusceptibility decreased in the sequence: protochlorophyll(ide), P-carotene, xanthophylls, Chl a, Chl b. In control seedlings the ratio E472/E437 or E486/E437 was 1.7-1.8-fold higher at the later phase than at the early phase of greening whereas the ratio F730/F684 reached approx. 0.40 or approx. 1.65 after 3- or 24-h greemng, respectively. Treatment of isolated thylakoids with high photon flux density caused a relative increase of the 472 and 486 nm band intensities in the excitation fluorescence spectrum of Chl, whereas the ratio F730/F684 increased only at the later phase investigated.
Rights:
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1824. Chloroplast protease/chaperone AtDeg2 holds γ1 subunit of ATP synthase in an unaggregated state under high irradiance conditions in Arabidopsis thaliana

Creator:
Jagodzik, P. and Jackowski, G.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
chaperone, Deg2, elevated irradiance, homodimerization, and protease
Language:
Multiple languages
Description:
Little data on the role played in vivo by chloroplast protein AtDeg2 as a chaperone is available. Therefore, we sought for chloroplast proteins protected from high irradiance-induced interprotein aggregation via disulphide bridges by AtDeg2 acting as a holdase. To reach this goal, we performed analyses which involved comparative diagonal electrophoreses of lysates of chloroplasts isolated from wild type (WT) plants and transgenic plants 35S:AtDEG2ΔPDZ1-GFP which expressed AtDeg2 lacking its chaperone activity but retaining the protease activity. The results of the analyses indicate that AtDeg2 acting as a holdase prevents a single chloroplast protein, i.e., the γ1 subunit of ATP synthase from long-term high irradiance-induced homodimerization mediated by disuplhide bridges and this allows us to better understand a complexity of physiological significance of AtDeg2 - the chloroplast protein of dual protease/chaperone activity.
Rights:
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1825. Chloroplast ribonucleoprotein-like proteins of the moss Physcomitrella patens are not involved in RNA stability and RNA editing

Creator:
Uchiyama, H., Ichinose, M., and Sugita, M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
RNA (nukleové kyseliny), ribonucleic acids, pentatricopeptide repeat protein, photosynthesis gene, posttranscriptional regulation, RNA-binding protein, RNA processing, 2, and 581
Language:
Multiple languages
Description:
Many RNA recognition motif (RRM)-containing proteins are known to exist in chloroplasts. Major members of the RRM protein family, which are chloroplast ribonucleoproteins (cpRNPs), have been investigated in seed plants, including tobacco and Arabidopsis thaliana, but never in early land plants, such as bryophytes. In this study, we surveyed RRM proteins encoded in the moss Physcomitrella patens genome and predicted 25 putative chloroplast RRM proteins. Among them, two RRM-containing proteins, PpRBP2a and PpRBP2b, resembled cpRNPs and were thus referred to as cpRNP-like proteins. However, knockout mutants of either one or two PpRBP2 genes exhibited a wild type-like phenotype. Unlike Arabidopsis cpRNPs, the levels of mRNA accumulation in chloroplasts were not affected in the PpRBP2 knockout mutants. In addition, the efficiency of RNA editing was also not altered in the mutants. This suggests that PpRBP2a and 2b may be functionally distinct from Arabidopsis cpRNPs., H. Uchiyama, M. Ichinose, M. Sugita., and Obsahuje bibliografické odkazy
Rights:
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1826. Chloroplast ultrastructural development during the ontogeny of the second leaf of wheat under nitrogen deficiency

Creator:
Kutík, J., Činčerová, A., and Dvořák, M.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Development of mesophyll cell chloroplasts during ontogeny of second wheat (Triticum aestivum L.) leaf was compared in plants grown in Ml nutrient solution (+N) and in nutrient solution without nitrogen (-N). Chloroplast size and ultrastructure were evaluated quantitatively by means of transmission electron microscopy and stereology. In -N plants compared to +N ones, the life spán of the second leaf was shortened and chloroplast development modified; the most striking feature was the accumulation of starch. Moreover, mature chloroplasts of -N plants were smaller and had smaller relative partial volume of thylakoids and larger relative partial volume of plastoglobules than those of +N plants.
Rights:
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1827. Chloroplast ultrastructure, photosynthesis and accumulation of secondary metabolites in Glechoma longituba in response to irradiance

Creator:
Zhang, L. X., Guo, Q. S., Chang, Q. S., Zhu, Z. B., Liu, L., and Chen, Y. H.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, gas exchange, light adaptation, stomatal index, thylakoid, triterpene acids, Glechoma longituba, 2, and 581
Language:
Multiple languages
Description:
Glechoma longituba (Nakai) Kupr. is a perennial shade plant with pharmaceutical importance. The aim of this study was to investigate the effects of light intensity on the growth, photosynthesis, and accumulation of secondary metabolites in G. longituba grown under six different light environments. The high light intensity decreased the leaf size, specific leaf area, and aboveground dry mass, the number of grana per chloroplast, the number of lamella per granum, the thickness of the grana, the apparent quantum efficiency, the chlorophyll (Chl) content, the concentrations of ursolic and oleanolic acid. The high light increased the stomatal density, the stoma size, the number of chloroplast per a cell, the chloroplast size, the dark respiration rate, the light saturation point, the light compensation point, and the Chl a/b ratio. With the reduction in the light intensity, the light-saturated net photosynthetic rate, the aerial dry mass per plant, and the yields of ursolic and oleanolic acid decreased after an initial increase, peaking at 16 and 33% of sunlight levels. Overall, the 16 and 33% irradiance levels were the most efficient in improving the yields and qualities of the medicinal plant. The lower light demand and growth characteristics suggest that G. longituba is an extremely shade-tolerant plant and that appropriate light intensity management might be feasible to obtain higher yields of secondary metabolites in agricultural management., L. X. Zhang, Q. S. Guo, Q. S. Chang, Z. B. Zhu, L. Liu, Y. H. Chen., and Obsahuje bibliografii
Rights:
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1828. Chloroplastic carbon dioxide concentration in Norway spruce (Picea abies [L.] Karst.) needles relates to the position within the crown

Creator:
Priwitzer, I., Urban, O., Šprtová, M., and Marek, M. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carboxylation capacity, electron transport rate, net photosynthetic rate, Norway spruce, ribulose-1,5-bisphosphate carboxylase/oxygenase, and sun/shade foliage
Language:
Multiple languages
Description:
Differences between sun (E) and shaded (S) foliage were studied in a Norway spruce (Picea abies [L.] Karst.) stand. Response curves describing the dependence of the CO2 assimilation rate (PN) on the CO2 concentration at the catalytic site of ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBPCO (PN-Cc) were estimated using the simultaneous measurements of chlorophyll fluorescence and leaf gas exchange. Higher PN, higher electron transport (Ja), higher carboxylation capacity (Vc), and higher RuBPCO activity (τ) for sun acclimated needles was found. The S-needles had higher portion of internal limitation and higher CO2 compensation concentration (Γ) than the E-needles. Because higher degree of limitation of photosynthesis by carboxylation was ascertained, it can be assumed that photosynthesis in shade foliage is limited mainly by lower carboxylation capacity and by low chloroplastic CO2 concentration. and I. Priwitzer ... [et al.].
Rights:
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1829. Chloroplastidic pigments, gas exchange, and carbohydrates changes during Carapa guianensis leaflet expansion

Creator:
Moraes, F. K. C., Castro, G. L. S., Silva Júnior, D. D. , Pinheiro, H. A., and Festucci-Buselli, R. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, carbohydrates, chlorophyll, leaf age, leaf expansion, and leaf gas exchange
Language:
Multiple languages
Description:
Changes in chloroplastidic pigments, gas exchange and carbohydrate concentrations were assessed during the rapid initial expansion of C. guianensis leaflet. Leaves at metaphyll stage were tagged and assessments were carried out 14, 17, 20, 23, 27, and 31 days later. Pigments synthesis, distribution and accumulation were uniform among leaflet sections (basal, median and apical). Chlorophyll (Chl) a, Chl b, Chl (a+b), and total carotenoids (Car) concentrations were significantly increased after 27 days from metaphyll, and the most expressive increases were parallel to lower specific leaflet area. Chl a/b was lower on day 14 and it was increased on subsequent days. Negative net photosynthesis rate (PN), and the lowest stomatal conductance (gs) and transpiration (E) were registered on day 14, following significant increases on subsequent days. The Chl (a+b) and Chl a effects on PN were more expressive until day 20. Intercellular to ambient CO2 concentration ratio (Ci/Ca) was higher on day 14 and lower on subsequent days, and no stomatal limitation to CO2 influx inside leaflets was observed. Leaflet temperature was almost constant (ca. 35°C) during leaflet development. Sucrose and starch concentrations were increased in parallel to increases in PN. Altogether, these results highlight the main physiological changes during C. guianensis leaflet expansion and they should be considered in future experiments focusing on factors affecting PN in this species. and F. K. C. Moraes ... [et al.].
Rights:
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